Coffee Science Alert n° 21
December 2008
AGRONOMY
Determination of chlorogenic acid in coffee using a biomimetic sensor based on a new tetranuclear copper(II) complex
de Carvalho, M. L.; Santhiago, M.; Peralta, R. A.; Neves, A.; Micke, G. A.; Vieira, I. C.
A new tetranuclear copper(II) complex which mimics the active site of catechol oxidase was synthesized and characterized by IR, CHN, electronic spectroscopic and (1)H NMR methods. The title complex [Cu(2)(mu-OH)(bpbpmp-NO(2))](2)[ClO(4)](2) was employed in the construction of a novel biomimetic sensor and used in the determination of chlorogenic acid by square wave voltammetry. The performance and optimization of the resulting biomimetic sensor were studied in detail. The best response of this sensor was obtained for 75:15:10% (w/w/w) ratio of the graphite powder:nujol:Cu(II) complex, 0.1 mol L(-1) phosphate buffer solution (pH 7.0), with frequency, pulse amplitude, and scan increment at 30 Hz, 100 mV, and 3.0 mV, respectively. The chlorogenic acid concentration was linear in the range of 5.0x10(-6) to 1.45x10(-4)mol L(-1) (r=0.9985) with a detection limit of 8.0x10(-7)mol L(-1). This biomimetic sensor demonstrated long-term stability (250 days; 640 determinations) and reproducibility, with a relative standard deviation of 10.0%. The recovery study of chlorogenic acid in coffee samples gave values from 93.2% to 106.1% and the concentrations determined showed good agreement when compared with those obtained using capillary electrophoresis at the 95% confidence level.
Source : Talanta 2008 vol.77 (1), pp 394 - 399
Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits
Geromel, C.; Pires-Ferreira, L.; Davrieux, F.; Guyot, B.; Ribeyre, F.; Santos-Scholz, M.-B. dos; Protasio- Pereira, L. F.; Vaast, P.; Pot, D.; Leroy, T.; Androcioli-Filho, A.; Esteves-Vieira, L. G.; Mazzafera, P.; Marracini, P.
Coffee fruits grown in full sunlight are smaller than coffee fruits grown in shade. Effects of shade on the development of coffee fruits and sugar metabolism were determined. Coffee fruits grown in shade were larger as a result of the greater development of perisperm tissue. Shade also reduced the sucrose content and increased the reducing sugars content of fresh and dried coffee beans. Higher activities of 2 enzymes (sucrose synthase (EC 2.4.1.13), sucrose-phosphate synthase (SPS: EC 2.4.1.14)) were detected in the pericarp and perisperm of fully matured shade-grown coffee fruits, and peak activities of both were higher in the developing endosperm. Expression of SUS-encoding genes was modified in shade-grown coffee fruits and levels of CaSUS2 transcripts were higher. Results suggest that sucrose metabolism is redirected in shade-grown coffee fruits.
Source : Plant Physiol Biochem 2008 vo/.46 (5-6), pp 569 - 579
Transmission efficiency of Xylella fastidiosa by sharpshooters (Hemiptera: Cicadellidae) in coffee and citrus
Marucci, R. C.; Lopes, J. R.; Cavichioli, R. R.
Xylella fastidiosa (Wells, Raju, Hung, Weisburg, Mandelco-Paul, and Brenner) is a bacterial pathogen transmitted by several sharpshooters in two tribes of Cicadellinae (Proconiini and Cicadellini). Here, we compared the transmission efficiency of X. fastidiosa in coffee (Coffea arabica L.) and citrus [Citrus sinensis (L.) Osbeck] by Cicadellini [Bucephalogonia xanthophis (Berg) and Dilobopterus costalimai Young] and Proconiini [Homalodisca ignorata Melichar and Oncometopia facialis (Signoret)] sharpshooters that occur in both crops. At different seasons, healthy adults of each species were submitted to a 48-h acquisition access period on citrus or coffee source plants infected with X. fastidiosa isolates that cause Citrus variegated chlorosis (CVC) and Coffee leaf scorch (CLS), respectively, and then confined on healthy seedlings of the corresponding host plant for a 48-h inoculation access period. No significant effect of inoculation season was observed when comparing infection rates of citrus or coffee plants inoculated by vectors at different times of the year. In citrus, the transmission rate by single insects was significantly higher for H. ignorata (30%) in relation to B. xanthophis (5%) and O. facialis (1.1%), but there was no difference among vector species in coffee, whose transmission rates ranged from 1.2 to 7.2%. Comparing host plants, H. ignorata was more effective in transmitting X. fastidiosa to citrus (30%) in relation to coffee (2.2%), whereas the other vectors transmitted the bacterium to both hosts with similar efficiencies. Despite these variations, vector efficiency in coffee and citrus is lower than that reported in other hosts.
Source : J Econ Entomol 2008 vol.101 (4), pp 1114 - 1121
Chemical characterisation of non-defective and defective green arabica and robusta coffees by
Mendonca, J.-C. F.; Franca, A. S.; Oliveira, L. S.; Nunes, M.
The coffee roasted in Brazil is considered to be of low quality, due to the presence of defective coffee beans that depreciate the beverage quality. These beans, although being separated from the non-defective ones prior to roasting, are still commercialized in the coffee trading market. Thus, it was the aim of this work to verify the feasibility of employing ESI-MS to identify chemical characteristics that will allow the discrimination of Arabica and Robusta species and also of defective and non-defective coffees. Aqueous extracts of green (raw) defective and non-defective coffee beans were analyzed by direct infusion electrospray ionization mass spectrometry (ESI-MS) and this technique provided characteristic fingerprinting mass spectra that not only allowed for discrimination of species but also between defective and non-defective coffee beans. ESI-MS profiles in the positive mode (ESI(+)-MS) provided separation between defective and non-defective coffees within a given species, whereas ESI-MS profiles in the
negative mode (ESI(-)-MS) provided separation between Arabica and Robusta coffees.
Source : Food Chemistry 2008 vol.111 (2), pp 490 - 497
BIOCHEMISTRY / BIOTECHNOLOGY
Limitations to photosynthesis in coffee leaves from different canopy positions
Araujo, W. L.; Dias, P. C.; Moraes, G. A.; Celin, E. F.; Cunha, R. L.; Barros, R. S.; Damatta, F. M.
Limitations to photosynthesis were explored in leaves from four canopy positions of field-grown, unshaded coffee (Coffea arabica L.), a tropical tree species classified as shade-obligatory. Overall, compared to shade (lower) leaves, sun (upper) leaves had higher net carbon assimilation rate (A) (4.5 against 2.0mumolm(-2)s(-1) at most) associated with higher electron transport rate (due to a greater irradiance availability) but unrelated to stomatal and mesophyll conductances, which were similar regardless of leaf position. Neither physiological variable directly involved with photosynthetic carbon gain nor those involved with light capture were able to adjust themselves to match the capacity of the photosynthetic machinery to the light supply. We concluded that: (i) there was no major difference in photosynthetic capacity between sun and shade leaves; (ii) the intrinsic low A in coffee was greatly associated with remarkable low diffusive limitations rather than with biochemical or photochemical constraints; and (iii) morphological (e.g., variations in specific leaf area and leaf inclination) or anatomical plasticity should be of greater acclimative value than physiological plasticity as a mean of coffee leaves to respond to changing irradiance .
Source : Plant Physiol Biochem 2008 vol.46 (10), pp 884 - 890
Caffeine clusters as transmitters of actinomycin antibiotics to DNA in solutions
Bitekhtina, M. A.; Vekshin, N. L.
Using the screening model of hypochromism, we showed that caffeine forms regular clusters consisting of 8-12 molecules. Addition of 7-aminoactinomycin D (7AAMD, a fluorescent analogue of actinomycin D) to the clusters leads to its sorption on the cluster surface. Photoexcitation of 7AAMD leads to its desorption from the surface into the aqueous phase and emission of a quantum. Fluorescence of 7AAMD in the presence of caffeine clusters is quenched by dinitrophenol more weakly than without clusters (the quenching constants are approximately 85 and approximately 280 M(-1), respectively) due to decreased steric availability of the antibiotic to the quencher. Addition of 7AAMD-caffeine complexes to DNA leads to a long-wavelength shift in the excitation spectrum and an increase in the fluorescence intensity along with a shift of the fluorescence spectrum to the short-wavelength area. This fact reflects redistribution of the antibiotic from the caffeine surface to the hydrophobic areas inside DNA. .
Source : Russian Journal of Bioorganic Chemistry 2008 vol. 34 (2) (English version)
ABA inhibits embryo cell expansion and early cell division events during coffee (Coffea arabica \'Rubi\') seed germination
Da Silva, E. A.; Toorop, P. E.; Van Lammeren, A. A.; Hilhorst, H. W.
Coffee seed germination represents an interplay between the embryo and the surrounding endosperm. A sequence of events in both parts of the seed determines whether germination will be successful or not. Following previous studies, the aim here was to further characterize the morphology of endosperm degradation and embryo growth with respect to morphology and cell cycle, and the influence of abscisic acid on these processes. METHODS: Growth of cells in a fixed region of the axis was quantified from light micrographs. Cell cycle events were measured by flow cytometry and by immunocytochemistry, using antibodies against beta-tubulin. Aspects of the endosperm were visualized by light and scanning electron microscopy. KEY RESULTS: The embryonic axis cells grew initially by isodiametric expansion. This event coincided with reorientation and increase in abundance of microtubules and with accumulation of beta-tubulin. Radicle protrusion was characterized by a shift from isodiametric expansion to elongation of radicle cells and further accumulation of beta-tubulin. Early cell division events started prior to radicle protrusion. Abscisic acid decreased the abundance of microtubules and inhibited the growth of the embryo cells, the reorganization of the microtubules, DNA replication in the embryonic axis, the formation of a protuberance and the completion of germination. The endosperm cap cells had smaller and thinner cell walls than the rest of the endosperm. Cells in the endosperm cap displayed compression followed by loss of cell integrity and the appearance of a protuberance prior to radicle protrusion.
CONCLUSIONS: Coffee seed germination is the result of isodiametric growth of the embryo followed by elongation, at the expense of integrity of endosperm cap cells. The cell cycle, including cell division, is initiated prior to radicle protrusion. ABA inhibits expansion of the embryo, and hence subsequent events, including germination.
Source : Ann Bot (Lond) 2008 vol.102 (3), pp 425 - 433
Inducible nature of the enzymes involved in catabolism of caffeine and related methylxanthines
Dash, S. S.; Gummadi, S. N.
Previously isolated strain of Pseudomonas sp. has the capability of utilizing caffeine as the sole source of carbon and nitrogen and degrading caffeine at higher concentrations (>10 g In this study, an assay has been developed to study the enzymatic conversion of caffeine to subsequent methylxanthines by cell free extracts of Pseudomonas sp., the activity of which has been stabilized by use of stabilizers in the lysis buffer. Growth of the strain in various methylxanthines and later enzyme assay demonstrated that the enzyme(s) involved in degradation of caffeine and other methylxanthines were inducible in nature. The results also indicated that more than one enzyme are involved in degradation of caffeine to xanthine, which constitute the primary steps in bacterial caffeine catabolism.
Source : J Basic Microbiol 2008 vol.48 (4), pp 227 - 233
Possible role of light and polyamines in the onset of somatic embryogenesis of Coffea canephora
De la Pena, C.; Galaz-Avalos, R. M.; Loyola-Vargas, V. M.
The concentration of free and bound polyamines was studied during the somatic embryogenesis induction process in Coffea canephora explants. In the present study we show that when the induction of somatic embryogenesis in C. canephora is carried out under light conditions and in the presence of the plant growth regulator, benzylaminopurine, a cytokinin, a faster response to induction is obtained. In the darkness, the response is delayed for more than 20 days, and the number of embryos is smaller. In the absence of benzylaminopurine no embryogenic response was observed. The pronounced changes in the levels of putrescine, spermidine, and spermine, both free and bound, found in C. canephora suggest that a close correlation exists between polyamine biosynthesis and somatic embryogenesis in C. canephora during a period of cellular differentiation associated with the induction of somatic embryogenesis.
Source : Mol Biotechnol 2008 vol.39 (3), pp 215 - 224
The relative contribution of human cytochrome P450 isoforms to the four caffeine oxidation pathways: an
Kot, M.; Daniel, W. A.
The aim of the present study was to estimate the relative contribution of cytochrome P450 isoforms (P450s), including P450s of the CYP2C subfamily, to the metabolism of caffeine in human liver. The experiments were carried out in vitro using cDNA-expressed P450s, liver microsomes and specific P450 inhibitors. The obtained results show that (1) apart from the 3-N-demethylation of caffeine - a CYP1A2 marker reaction and the main oxidation pathway of caffeine in man - 1-N-demethylation is also specifically catalyzed by CYP1A2 (not reported previously); (2) 7-N-demethylation is catalyzed non-specifically, mainly by CYP1A2 and, to a smaller extent, by CYP2C8/9 and CYP3A4 (and not by CYP2E1, as suggested previously); (3) C-8-hydroxylation preferentially involves CYP1A2 and CYP3A4 and, to a smaller degree, CYP2C8/9 and CYP2E1 (and not only CYP3A, as suggested previously) at a concentration of 100 microM corresponding to the maximum therapeutic concentration in humans. At a higher caffeine concentration, the contribution of CYP1A2 to this reaction decreases in favour of CYP2C8/9. The obtained data show for the first time the contribution of CYP2C isoforms to the metabolism of caffeine in human liver and suggest that apart from 3-N-demethylation, 1-N-demethylation may also be used for testing CYP1A2 activity. Moreover, they indicate that the C-8-hydroxylation is not exclusively catalyzed by CYP3A4.
Source : Biochem Pharmacol 2008 vol.76 (4), pp 543 - 551
R-Coffee: a web server for accurately aligning noncoding RNA sequences
Moretti, S.; Wilm, A.; Higgins, D. G.; Xenarios, I.; Notredame, C.
The R-Coffee web server produces highly accurate multiple alignments of noncoding RNA (ncRNA) sequences, taking into account predicted secondary structures. R-Coffee uses a novel algorithm recently incorporated in the T-Coffee package. R-Coffee works along the same lines as T-Coffee: it uses pairwise or multiple sequence alignment (MSA) methods to compute a primary library of input alignments. The program then computes an MSA highly consistent with both the alignments contained in the library and the secondary structures associated with the sequences. The secondary structures are predicted using RNAplfold. The server provides two modes. The slow/accurate mode is restricted to small datasets (less than 5 sequences less than 150 nucleotides) and combines R-Coffee with Consan, a very accurate pairwise RNA alignment method. For larger datasets a fast method can be used (RM-Coffee mode), that uses R-Coffee to combine the output of the three packages which combines the outputs from programs found to perform best on RNA (MUSCLE, MAFFT and ProbConsRNA). Our BRAliBase benchmarks indicate that the R-Coffee/Consan combination is one of the best ncRNA alignment methods for short sequences, while the RM-Coffee gives comparable results on longer sequences. The R-Coffee web server is available at http://www.tcoffee.org.
Source : Nucleic Acids Res 2008 vol.36 (Web Server issue), pp W10 - W13 (full text)
Characterization and expression analysis of genes directing galactomannan synthesis in coffee
Pre, M.; Caillet, V.; Sobilo, J.; McCarthy, J.
Galactomannans act as storage reserves in seeds of some plants such as guar (Cyamopsis tetragonoloba) and coffee (Coffea arabica and Coffea canephora). In coffee, the galactomannans can represent up to 25 % of the mass of the mature green coffee grain, and they exert a significant influence on the production of different types of coffee products. The objective of the current work was to isolate and characterize cDNA encoding proteins responsible for galactomannan synthesis in coffee and to study the expression of the corresponding transcripts in the developing coffee grain from C. arabica and C. canephora, which potentially exhibit slight galactomannan variations. Comparative gene expression analysis was also carried out for several other tissues of C. arabica and C. canephora. cDNA banks, RACE-PCR and genome walking were used to generate full-length cDNA for 2 putative coffee mannan synthases (ManS) and 2 galactomannan galactosyl transferases (GMGT). Gene-specific probe-primer sets were then generated and used to carry out comparative expression analysis of the corresponding genes in different coffee tissues using quantitative RT-PCR. 2 of the putative galactomannan biosynthetic genes, ManS1 and GMGT1, were demonstrated to have very high expression in the developing coffee grain of both Coffea spp. during endosperm development, consistent with our proposal that these 2 genes are responsible for the production of the majority of the galactomannans found in the grain. In contrast, the expression data presented indicates that the ManS2 gene product is probably involved in the synthesis of the galactomannans found in green tissue. It is concluded that the identification of genes implicated in galactomannan synthesis in coffee are presented. The data obtained will enable more detailed studies on the biosynthesis of this important component of coffee grain and contribute to a better understanding of some functional differences between grain from C. arabica and C. canephora.
Source : Annals of Botany 2008 vol.102 (2), pp 207 - 220
Aluminium induces changes in organic acids metabolism in Coffea arabica suspension cells with differential Al-tolerance
Ramirez-Benitez, J. E.; Chee-Gonzalez, L.; Hernandez-Sotomayor, S. M.
The primary Al-tolerance mechanism in plants involves exudation and/or accumulation of specific organic acid species, which form non-phytotoxic complexes with Al(3+) under physiological conditions. An evaluation was done of the role of organic acids in the tolerance mechanism of a cell suspension line of coffee Coffea arabica that exhibits Al-tolerance (LAMt) but for which the metabolic tolerance mechanism remains unknown. Significant differences existed in malate dehydrogenase and citrate synthase activities (key enzymes in organic acids metabolism) between protein extracts (day 7 of culture cycle) of the L2 (Al-sensitive) and LAMt (Al-tolerant) cells when cell suspensions were treated with 100 microM AlCl(3). HPLC analysis showed that the suspension cells of both lines exudate malate when incubated in a minimal solution but that exudation was not enhanced by treatment with AlCl(3) (100 microM). This is the first study demonstrating that plant Al-tolerance may be associated with down-regulation of malate dehydrogenase and citrate synthase activities.
Source : J Inorg Biochem 2008 vol.102 (8), pp 1631 - 1637
Fast inhibition of glutamate-activated currents by caffeine Source
Vyleta, N. P.; Smith, S. M.
Caffeine stimulates calcium-induced calcium release (CICR) in many cell types. In neurons, caffeine stimulates CICR presynaptically and thus modulates neurotransmitter release. METHODOLOGY/PRINCIPAL FINDINGS: Using the whole-cell patch-clamp technique we found that caffeine (20 mM) reversibly increased the frequency and decreased the amplitude of miniature excitatory postsynaptic currents (mEPSCs) in neocortical neurons. The increase in mEPSC frequency is consistent with a presynaptic mechanism. Caffeine also reduced exogenously applied glutamate-activated currents, confirming a separate postsynaptic action. This inhibition developed in tens of milliseconds, consistent with block of channel currents. Caffeine (20 mM) did not reduce currents activated by exogenous NMDA, indicating that caffeine block is specific to non-NMDA type glutamate receptors.
CONCLUSIONS/SIGNIFICANCE: Caffeine-induced inhibition of mEPSC amplitude occurs through postsynaptic block of non-NMDA type ionotropic glutamate receptors. Caffeine thus has both pre and postsynaptic sites of action at excitatory synapses.
Source : PLoS ONE 2008 vol.3 (9), pp e3155
5 Caffeoylquinic acid and caffeic acid down-regulate the oxidative stress- and TNF-alpha-induced secretion of interleukin-8 from Caco-2 cells
Zhao, Z.; Shin, H. S.; Satsu, H.; Totsuka, M.; Shimizu, M.
Chlorogenic acid (CHA) is found in coffee beverages, blueberries, apples, cider and some vegetables, and this study investigated the down-regulative effects of 5-caffeoylquinic acid, the main isomer of CHA, on the hydrogen peroxide- or tumour necrosis factor-alpha-induced secretion of interleukin-8, a chemokine involved in the pathogenesis of inflammatory bowel diseases, in human intestinal epithelial Caco-2 cells. The concentration of 5-caffeoylquinic acid found in common brewed coffee suppressed interleukin-8 secretion in human intestinal epithelial cells, and the use of coffee for preventing the genesis of inflammatory bowel diseases is suggested.
Source : J Agric Food Chem 2008 vol.56 (10), pp 3863-3868
MICROBIOLOGY
Two novel species of Aspergillus section Nigri from Thai coffee beans
Noonim, P.; Mahakarnchanakul, W.; Varga, J.; Frisvad, J. C.; Samson, R. A.
Two novel species of Aspergillus section Nigri from Thai coffee beans are described as A. aculeatinus sp. nov. and A. sclerotiicarbonarius sp. nov. Their taxonomic status was determined using a
polyphasic taxonomic approach with phenotypic (morphology and extrolite profiles) and molecular (beta-tubulin, internal transcribed spacer and calmodulin gene sequences) characteristics. A. aculeatinus sp. nov. is a uniseriate species with a similar morphology to A. aculeatus and A. japonicus, but producing smaller conidia (2-5 mum). A. aculeatinus sp. nov. produced neoxaline, secalonic acid D and F, and aculeacins. A. sclerotiicarbonarius sp. nov. is a biseriate species similar to A. carbonarius and A. ibericus, but produces abundant sclerotia and some unique indol-alkaloids. The type strain of A. sclerotiicarbonarius sp. nov. is CBS 121057T (= IBT 28362T) and the type strain of A. aculeatinus sp. nov. is CBS 121060T (=IBT 29077T).
Source : Intern J Systematic and Evolutionary Microbio 2008 vol.58 (7), pp 1727 - 1734
A genus-specific PCR method for differentiation between Leuconostoc and Weissella and its application
Schillinger, U.; Boehringer, B.; Wallbaum, S.; Caroline, L.; Gonfa, A.; Huch-Nee-Kostinek, M.; Holzapfel, W.
H.; Franz, C. M.
A genus-specific PCR analysis method was developed for a rapid and reliable differentiation between the two heterofermentative lactic acid bacteria genera Leuconostoc and Weissella. Primer sets specific for target regions of the 16S rRNA genes were designed and the specificity of the PCR was evaluated using the type strains of 13 species of Leuconostoc and 11 species of Weissella. In addition, the newly developed genus-specific PCR analysis was applied to characterize 72 lactic acid bacteria (LAB) strains isolated from coffee fermentation and which were presumptively classified as Leuconostoc or Weissella species. Additionally, a total of 34 LAB isolates from various other fermented foods were included. The investigations of these strains were conducted to test the effectiveness of correct characterization of field isolates using the genus-specific PCR approach. The correct assignment to one of these two genera by the application of the genus-specific primers was confirmed by further identifying the strains using repetitive extragenic palindromic-PCR and 16S rRNA gene sequencing.
Source : FEMS Microbiol Lett 2008 vol.286 (2), pp 222 - 226
Antiviral activities of coffee extracts in vitro
Utsunomiya, H.; Ichinose, M.; Uozaki, M.; Tsujimoto, K.; Yamasaki, H.; Koyama, A. H.
The hot-water extract of coffee beans contains physiologically active substances, and beneficial health effects have been reported for coffee. Caffeine has been found to have antiherpetic activity, and this study examined the antiviral effects of coffee extracts. Hot-water extracts of coffee grinds and instant coffee solutions inhibited the multiplication of herpes simplex virus type-1 when added to the culture medium of virus-infected cells. The mechanisms by which coffee extracts exerted inhibitory activities against virus infection are described. Coffee extracts also inhibited the multiplication of poliovirus, but had no virucidal effect.
Source : Food Chem Toxicol 2008 vol.46 (6), pp 1919-1924
PROCESSING
Modeling of caffeine release from crosslinked water-swellable gelatin and gelatin-maltodextrin hydrogels
Abbasi, A.; Eslamian, M.; Rousseau, D.
Research from this group has recently led to the development of a genipin-crosslinked gelatin gel that may be used as a controlled release matrix for bioactive compounds. This study presents a model that simulates the release of entrapped caffeine from the hydrogel and the ingress of water into these gels. Fick's second law of diffusion is used to describe the water penetration and bioactive release in the system. To validate the model, caffeine release experiments from the gel were carried out. The predicted bioactive release profiles are in very good agreement with experimental data at different gel compositions. The model may also be used for a wide range of bioactive molecules and hydrogels with different cylindrical dimensions.
Source : Drug Deliv 2008 vol. 15 (7), pp 455 - 463
Near infrared spectroscopy: an analytical tool to predict coffee roasting degree
Alessandrini, L.; Romani, S.; Pinnavaia, G.; Dalla-Rosa, M.
The main purpose of this study was to investigate the relationship between some coffee roasting variables (weight loss, density and moisture) with near infrared (NIR) spectra of original green (i.e. raw) and differently roasted coffee samples, in order to test the availability of non-destructive NIR technique to predict coffee roasting degree. Separate calibration and validation models, based on partial least square (PLS) regression, correlating NIR spectral data of 168 representatives and suitable green and roasted coffee samples with each roasting variable, were developed. Using PLS regression, a prediction of the three modelled roasting responses was performed. High accuracy results were obtained, whose root mean square errors of the residuals in prediction (RMSEP) ranged from 0.02 to 1.23%. Obtained data allowed to construct robust and reliable models for the prediction of roasting variables of unknown roasted coffee samples, considering that measured vs. predicted values showed high correlation coefficients (r from 0.92 to 0.98). Results provided by calibration models proposed were comparable in terms of accuracy to the conventional analyses, revealing a promising feasibility of NIR methodology for on-line or routine applications to predict and/or control coffee roasting degree via NIR spectra.
Source : Anal Chim Acta 2008 vol.625 (1), pp 95 - 102
Prediction of brightness and surface area kinetics during coffee roasting
Hernandez, J. A.; Heyd, B.; Trystram, G.
The amount of heat transferred to green coffee beans is essential in the coffee roasting. During this process, several parameters can be used as indicators to determine the degree of roasting (color, aroma, volume, bean temperature). Consequently, two predictive models, using artificial neural networks, are proposed to determine the quality of coffee roasting. A bean brightness model took account of bean temperature (simulated by a physical model) and roasting time. A second model predicting the bean surface area, focused on roasting air temperature and roasting time. The color changes affecting coffee beans during the process were studied experimentally in a pilot roaster equipped with a CCD video camera and a lighting system consisting of two small optic fiber spotlights. Arabica green coffee beans of Colombian origin were roasted using different air temperatures (190, 200, 210, ... 300°C), for 10min. Two separate feedforward networks with one hidden layer were used to brightness and surface kinetics. The best fitting training data set was obtained using three neurons in the hidden layer, which enable prediction of brightness and bean surface kinetics with an accuracy that was at least as good as the experimental error, over the entire experimental range. Using the validation data set, simulations and experimental data were in good agreement (R2>0.98). This study showed that real-time simulations were possible so that the roasting process could be stopped when the simulated brightness was similar to a target fixed by the roast master. The model thus developed could contribute to the on-line estimation of product quality, thus providing a parameter to control coffee roasting.
Source : J Food Eng 2008 vol.89 (2), pp 156 - 163
Structure expansion of green coffee beans using instantaneous controlled pressure drop process
Kamal, I. M.; Sobolik, V.; Kristiawan, M.; Mounir, S. M.; Allaf, K.
Since 1988, when the first experiments with the Instantaneous Controlled Pressure Drop (DIC) process were performed, a lot of investigations have been carried out concerning the structure expansion, processing kinetics (drying, extraction and sterilization) and the improvement of the functional and organoleptic properties of fresh and dried foods. In this study, two DIC technologies were used to expand the structure of green coffee beans. Two varieties of commercial Arabica coffee beans of different agricultural and geographical origins (Brazilian and Ethiopian) were inspected. The effect of initial moisture content (7-40% dry basis), type of heating in the DIC process (steam and microwaves), processing parameters like pressure (0.4-0.7 MPa) and heating time (20-200 s) on bean expansion were investigated. The expansion was evaluated as the ratio of the tapped density of raw beans to that of the treated material. The hydration capacity of the beans was also studied. The Response Surface Methodology was employed to optimize the processing parameters. After the steam DIC treatment, the maximum expansion ratio of the Brazilian beans (e =1.74) was higher than that of the Ethiopian beans (e=1.59). For Brazilian beans, the steam DIC treatment resulted in a higher value of expansion ratio than the MW DIC treatment (e=1.39). Concerning hydration capacity, the steam DIC treatment gave values of 78.6% and 48.2% d.b. for the Ethiopian and Brazilian beans, respectively. It means almost two-fold increase in the hydration capacity using DIC treatment. The steam DIC treatment increased and accelerated in twice the weight loss of beans during roasting. Industrial relevance: Preliminary experiments have shown that the structure expansion of green coffee beans significantly reduced the roasting time, amended the bean suitability to grinding and improved the kinetics and yield of caffeine and active compounds extraction. The industrial DIC processes can be distinguished by high quality of final products, energy saving and positive environmental impact. Due to the fragile structure of coffee beans, a batch process should be applied. Industrial plant can be designed as a tower plant with several compartments separated by guillotine valves where the material falls down by gravity force or a carrousel or a linear plant with filling, DIC treatment and discharging operations. The ABCAR DIC Process Company (La Rochelle, France) develops plants with a capacity of 50 kg/h to 8 ton/h of dry coffee beans. Despite the promising experimental results concerning microwave DIC technology, the industrial applications are so far limited to the steam DIC treatment due to technical reasons.
Source : Innovative Food Science and Emerging Technologies 2008 vol.9 (4), pp 534 - 541
Design and implementation of an integrated management system for ochratoxin A in the coffee production chain
Lopez-Garcia, R.; Mallmann, C. A.; Pineiro, M.
Coffee is an important export product of Ecuador. Producers are challenged by the implementation of regulatory limits for ochratoxin A. Ecuador has four coffee production areas and the potential for mycotoxin contamination varies due to different environmental conditions and cultural differences in harvesting, storage, processing and commercialization. The major contributors to contamination are the lack of selection during harvesting, delays in drying or rewetting, the lack of proper drying and storage conditions, the mixing of products with different levels of moisture, and the potential for cross-contamination. The long commercialization chain involves different intermediaries that use foreign materials to increase the weight of the product without consideration of quality. An integrated mycotoxin management system using the Hazard Analysis Critical Control Point Systems (HACCP) principles was developed to prevent mycotoxin contamination at each stage of production. Critical control points were developed based on the resources available at the different stages of the production chain. Training programmes helped increase awareness about the impact of contamination, but failed to transform knowledge into improved practices. Thus, different demonstrative models specific for each productive region at all production levels were developed to show the application of prevention mechanisms using limited resources and to demonstrate the increased commercial value of coffee produced using good practices throughout the chain so producers have a better disposition to adopt improved practices. Preliminary results show that coffee managed using the models had a better quality, a lower contamination, a higher yield and better commercial value. The use of local resources and low-cost technology was important in demonstrating the practical approach.
Source : Food Addit Contam 2008 vol.25 (2), pp 231 - 240
Ozone and ultrasound: alternative processes in the treatment of fermented coffee
Nascimento, L.-C. do; Oliveira-Lima, L.-C. de; Hilsdorf-Picolli, R.; Fiorini, J. E.; Silveira-Duarte, S.-M. da;
Schneedorf-Ferreira-da-Silva, J. M.; Mello-Silva-Oliveira, N. de; Oliveira-Morais-Veiga, S.-M. de
After water, coffee is the most consumed beverage on the planet, with a rising demand for special types, such as fermented coffee, in some importing countries. This type of coffee is obtained by removing the mucilage, submitting the coffee to fermentation, a process that varies with the climate and the associated natural microorganisms, among other factors, and that can lead to detrimental effects to the quality of the product and to the health of consumers. Thus, it is necessary to investigate new technologies that can help obtain better standardized products, of higher quality and that offer greater food safety. Ozone and ultrasound are technologies used in various areas, with great flexibility and promising results in the production and treatment of an infinity of food products. The potent oxidant and antimicrobial characteristics of both are well-known, however, their mechanisms are still not clearly understood when used in live tissues. Their effects on the various quality parameters must be studied, understood and adjusted, before widespread use in the food industry. In the present paper, ozone or ultrasound were applied as pre-treatments before coffee fermentation, demonstrating their efficacy in improving the safety of the fermented coffee, without perceptible changes in the quality of the beverage.
Source : Ciencia e Tecnologia de Alimentos.2008 vol.28 (2), pp 282 - 294
Evaluation of untreated coffee husks as potential biosorbents for treatment of dye contaminated waters
Oliveira, L. S.; Franca, A. S.; Alves, T. M.; Rocha, S. D.
The objective of this work was to propose an alternative use for coffee husks (CH), a coffee processing residue, as untreated sorbents for the removal of methylene blue (MB) from aqueous solutions. The effects of solution temperature, pH, biosorbent dosage and contact time on MB removal were investigated. The experimental adsorption equilibrium data were fitted to both Langmuir and Freundlich adsorption models. The biosorption kinetics was determined by fitting first and second-order kinetic models to the experimental data, with the second-order model providing the best description of MB adsorption onto coffee husks. pH variations did not present a significant effect on MB removal. Evaluation of thermodynamics parameters indicated that the adsorption is spontaneous and endothermic. The experimental data obtained in the present study demonstrated coffee husks to be suitable candidates for use as biosorbents in the removal of cationic dyes.
Source : J Hazard Mater 2008 vol.155 (3), pp 507 - 512
Influence of preparation conditions in the textural and chemical properties of activated carbons from a novel biomass precursor: the coffee endocarp
Valente-Nabais, J.; Carrott, P.; Ribeiro-Carrott, M.-M. L.; Luz, V.; Ortiz, A. L.
Utilization of coffee bean endocarp, a coffee processing waste, as a substrate for production of activated C is reported. Physical and chemical activation methods were tested, and the morphology and surface chemistry of the resulting activated C preparations were characterized. Preparations with small surface area and pore vol. of <less than or equal to>0.22 and <less than or equal to>0.43 cm3/g were generated via activation using CO2 and KOH, respectively, and all preparations were highly basic.
Source : Bioresource Technology 2008 vol.99 (15), pp 7224 - 7231
CHEMISTRY / SENSORICS
Effect of roasting degree, equivalent thermal effect and coffee type on the radical scavenging activity of coffee brews and their phenolic fraction
Sacchetti, G.; Mattia, C. di; Pittia, P.; Mastrocola, D.
The radical scavenging activity (RSA) of coffee brews obtained from different types of coffee was studied as a function of the roasting degree and equivalent thermal effect (expressed as CTrefz), and the relative contribution of the phenolic fraction (PF) and non-phenolic fraction (NPF) to the overall RSA was evaluated. Brews extracted from medium roasted coffee showed a higher RSA than those from green coffee due to an increase of the RSA of the NPF upon roasting. The RSA of the NPF increased with increasing roasting degree together with the accumulation of brown coloured Maillard reaction products (MRPs). Brews from dark coffee showed lower RSA than those from medium roasted coffee due to polyphenols degradation which, in turn, caused an RSA depletion not counterbalanced by an increase of the RSA of NPF. The relative contribution of NPF to the overall RSA of the brew is in fact much lower than that of the PF. Roasting processes with similar CTrefz values resulted in the same RSA independent of an average temperature variation from 170 to 190°C and coffee type. The AOA changes in brews from commercial coffee samples (medium and dark roasted) were more dependent on roasting severity than on the type of coffee.
Source : J Food Engin 2009 vol.90 (1), pp 74 - 80 (full text)
Determination of acrylamide during roasting of coffee
Bagdonaite, K.; Derler, K.; Murkovic, M.
In this study different Arabica and Robusta coffee beans from different regions of the world were analyzed for acrylamide after roasting in a laboratory roaster. Due to the complex matrix and the comparably low selectivity of the LC-MS at m/ z 72, acrylamide was analyzed after derivatization with 2-mercaptobenzoic acid at m/ z 226. Additionally, the potential precursors of acrylamide (3-aminopropionamide, carbohydrates, and amino acids) were studied. The highest amounts of acrylamide formed in coffee were found during the first minutes of the roasting process [3800 ng/g in Robusta ( Coffea canephora robusta) and 500 ng/g in Arabica ( Coffea arabica)]. When the roasting time was increased, the concentration of acrylamide decreased. It was shown that especially the roasting time and temperature, species of coffee, and amount of precursors in raw material had an influence on acrylamide formation. Robusta coffee contained significantly larger amounts of acrylamide (mean = 708 ng/g) than Arabica coffee (mean = 374 ng/g). Asparagine is the limiting factor for acrylamide formation in coffee. 3-Aminopropionamide formation was observed in a dry model system with mixtures of asparagine with sugars (sucrose, glucose). Thermal decarboxylation and elimination of the alpha-amino group of asparagine at high temperatures (>220 degrees C) led to a measurable but low formation of acrylamide.
Source : J Agric Food Chem 2008 vol.56 (15), pp 6081 - 6086
Roasting and aroma formation: effect of initial moisture content and steam treatment
Baggenstoss, J.; Poisson, L.; Kaegi, R.; Perren, R.; Escher, F.
Initial moisture content of green coffee may vary as a function of green coffee processing and storage conditions. The impact of initial moisture and steam treatment on roasting behaviour and aroma formation was investigated. Steam treated coffees, as well as coffees with initial moisture contents of 5.10, 10.04 and 14.70 g water per 100 g were roasted. Light and dark roasting trials were carried out using a fluidizing-bed roaster with a batch size of 100 g of green beans. Differences in roast coffee attributes, including colour, density and organic roast loss, and odorant concn. were more marked in light roasted than in dark roasted coffees. The results of roasting steam treated coffee suggest that this step affects roasting behaviour primarily by extracting some aroma precursor compounds.
Source : J Agric Food Chem 2008 vol.56 (14), pp 5847 - 5851
Coffee roasting and aroma formation: application of different time-temperature conditions
Baggenstoss, J.; Poisson, L.; Kaegi, R.; Perren, R.; Escher, F.
The impact of time-temp. combinations of roasting processes on the kinetics of aroma formation in coffee was investigated. The development of 16 aroma compounds and the physical properties of coffee beans were followed in a commercial horizontal drum roasting process and in laboratory scale fluidizing-bed roasting processes under high temp.-short time and low temp.-long time conditions. All trials were run to an equal roast end point as defined by the lightness of coffee beans. In addition, the effect of excessive roasting on aroma composition was studied. Compared to low temp.-long time roasting, high temp.-short time roasting resulted in considerable differences in the physical properties and kinetics of aroma formation. Excessive roasting generally led to decreasing or stable amounts of volatile substances, except for hexanal, pyridine and dimethyl trisulfide, whose concn. continued to increase during over-roasting. When the drum roaster and the fluidizing bed roaster were operated in the so-called temp. profile mode, that is, along the identical development of coffee bean temp. over roasting time, the kinetics of aroma generation were similar in both processes.
Source : J Agric Food Chem 2008 vol.56 (14), pp 5836 - 5846
Roasting effects on formation mechanisms of coffee brew melanoidins
Bekedam, E. K.; Loots, M. J.; Schols, H. A.; Van Boekel, M. A.; Smit, G.
The effect of the roasting degree on coffee brew melanoidin properties and formation mechanisms was studied. Coffee brew fractions differing in molecular weight (Mw) were isolated from green and light-, medium-, and dark-roasted coffee beans. Isolated fractions were characterized for their melanoidin, nitrogen, protein, phenolic groups, chlorogenic acid, quinic acid, caffeic acid, and sugar content. It was found that the melanoidin level in all fractions correlated with both the nitrogen and the protein content.The melanoidin level also correlated with the phenolic groups' level and ester-linked quinic acid level. It was concluded that proteins and chlorogenic acids should be primarily involved in melanoidin formation. Initial roasting, from green to light-roasted beans, especially led to the formation of intermediate Mw (IMw) melanoidins when compared to high Mw (HMw) melanoidins. Indications were found that this IMw melanoidin formation is mainly due to Maillard reactions and chlorogenic acid incorporation reactions between chlorogenic acids, sucrose, and amino acids/protein fragments. Additionally, it was found that prolonged roasting predominantly led to formation melanoidins with a high Mw. Furthermore, arabinogalactans seem to be relatively more involved in melanoidin formation than galactomannans. It was hypothesized that chromophores may be formed or attached through the arabinose moiety of arabinogalactan proteins (AGP). Finally, it could be concluded that galactomannans are continuously incorporated in AGP-melanoidins upon roasting.
Source : J Agric Food Chem 2008 vol.56 (16), pp 7138 - 7145
Group-type and fingerprint analysis of roasted food matrices (coffee and hazelnut samples) by
Cordero, C.; Bicchi, C.; Rubiolo, P.
The present study is focused on the volatile fraction of roasted hazelnut and coffee samples, differing in botanical origins, morphological characteristics, and roasting treatments, selected as challenging matrices. Volatile components, sampled by headspace solid phase microextraction (HS-SPME), were analyzed by GCxGC-qMS, and separation results were adopted to classify, correlate, and/or compare samples and evaluate processing effects. The high-complexity sample profiles were interpreted through different methods: a group-type characterization, a direct fingerprint comparison, and a template matching to extract useful and consistent information, and advantages and limits of each specific approach were critically evaluated. The group-type analysis, focused on several known botanical and technological markers, enabled sample comparison and characterization based on their quali-quantitative distribution; it is highly reliable, because of the authentic standard confirmation, and extends the comparative procedure to trace and minor components. Fingerprint approaches (i.e., direct fingerprint comparison and template matching), on the other hand, extended sample comparisons and correlations to the whole volatiles offering an increased discrimination potential and improved sensitivity due to the wider analyte pattern considered. This study demonstrates the ability of comprehensive GC to further explore the complexity of roasted samples and emphasizes the advantages of, and the need for, a comprehensive and multidisciplinary approach to interpret the increased level of information provided by GCxGC separation in its full complexity.
Source : J Agric Food Chem 2008 vol.56 (17), pp 7655 - 7666
Identification and in vitro cytotoxicity of ochratoxin A degradation products formed during coffee roasting
Cramer, B.; Koenigs, M.; Humpf, H. U.
The mycotoxin ochratoxin A is degraded by up to 90% during coffee roasting. In order to investigate this degradation, model heating experiments with ochratoxin A were carried out, and the reaction products were analysed by HPLC-DAD and HPLC-MS/MS. 2 ochratoxin A degradation products were identified, and their structure and absolute configuration were determined. As degradation reactions, the isomerization to 14-(R)-ochratoxin A and the decarboxylation to 14-decarboxy-ochratoxin A were identified. Subsequently, an analytical method for the determination of these compounds in roasted coffee was developed. Quantification was carried out by HPLC-MS/MS and the use of stable isotope dilution analysis. By using this method for the analysis of 15 coffee samples from the German market, it could be shown that, during coffee roasting, the ochratoxin A diastereomer 14-(R)-ochratoxin A was formed in amounts of up to 25.6% relative to ochratoxin A. The decarboxylation product was formed only in traces. For toxicity evaluations, 1st preliminary cell culture assays were performed with the 2 new substances. Both degradation products exhibited higher IC50 values and caused apoptotic effects with higher concn. than ochratoxin A in cultured human kidney epithelial cells. Thus, these cell culture data suggest that the degradation products are less cytotoxic than ochratoxin A.
Source : J Agric Food Chem 2008 vol.56 (14), pp 5673 - 5681
Genetic diversity and correlation of bean caffeine content with cup quality and green bean physical characteristics in coffee (Coffea arabica L.)
Dessalegn, Y.; Labuschagne, M. T.; Osthoff, G.; Herselman, L.
Caffeine concn. were determined in 42 Ethiopian genotypes of arabica coffee and association of caffeine concn. with coffee bean physical properties and cup quality was studied. Caffeine concn. in green coffee beans was in the range 9.1-13.2 g/kg (DM basis) as determined by HPLC, with 6 genotypes having caffeine concn. of <10 g/kg. Correlations between caffeine concn. and physical properties of green beans (shape, size, wt. and uniformity) were negative but non-significant. Caffeine concn. was negatively and significantly associated with all cup quality parameters. Results are discussed with regard to genetic improvement for improved cup quality combined with low caffeine concn.
Source : J Sci Food Agric 2008 vol.88 (10), pp 1726 - 1730
Characterization and fermentability of an ethanol soluble high molecular weight coffee fraction
Gniechwitz, D.; Reichardt, N.; Meiss, E.; Ralph, J.; Steinhart, H.; Blaut, M.; Bunzel, M.
It is suspected that coffee brews contain considerable amounts of high mol. wt. components (melanoidins, ethanol soluble polysaccharides) that are not detected as dietary fibre using enzymic-gravimetric methodology but either belong to the dietary fibre complex or possess fibre-like properties. The aim of this study was to analyse the content and to determine the physicochemical characteristics and fermentability of a high mol. wt. ethanol soluble coffee fraction. Brews from differently roasted Arabica coffees were shown to contain 8-12% ethanol soluble substances with molecular masses >2 kDa, possibly contributing to their dietary fibre contents. About 13% of these substances were nondigestible carbohydrates, mainly arabinogalactans. The nondigestible high mol. wt. ethanol soluble fraction (HESF) of the medium roasted coffee brew was further characterized and subjected to in vitro fermentation with human faecal bacteria. In addition to carbohydrates, HESF contained proteins/peptides (approx. 20%), but the main fraction was composed of structurally unknown Maillard reaction products. From NMR spectroscopy, it is concluded that intact caffeic and ferulic acid derivatives were not incorporated into the melanoidins to a significant extent. Stepwise ultrafiltration and gel filtration indicated a large variation in the mol. wt. of HESF constituents. Coffee HESF was shown to be less fermentable by faecal bacteria than soluble coffee fibre isolated by the enzymic-gravimetric methodology, and because of its lower carbohydrate content, less short-chain fatty acids were produced during the fermentation. Total cell counts, destructive chemical analysis and NMR spectroscopy indicated that coffee carbohydrates are the preferred substrates for colonic microbiota. However, NMR spectra, absorbances at 405 nm and nonprotein nitrogen contents showed that noncarbohydrate and nonprotein compounds were also utilized to some extent but the bacterial species involved in this degradation remain to be identified.
Source : J Agric Food Chem 2008 vol.56 (14), pp 5960 - 5969
Investigation of the parameters influencing the content and composition of fibre in coffee drinks
Gniechwitz, D.; Bruckel, B.; Reichardt, N.; Blaut, M.; Steinhart, H.; Bunzel, M.
This item reports on research into the content and composition of fibre used in coffee drinks. This fibre takes the form of polysaccharides, particularly galactomannan and arabinogalactan, used in roast coffee, including both Robusta and Arabica. The level of fibre was lower in decaffeinated filter coffee.
Source : Lebensmittelchemie 2008 vol.62 (3), pp 73-74 (not available on line)
Simultaneous analysis of vitamins and caffeine in energy drinks by surfactant-mediated matrix-assisted laser desorption/ionization
Grant, D. C.; Helleur, R. J.
As a new approach to rapid small-molecule analysis, surfactant-mediated MALDI-TOF-MS was used successfully for the analysis of caffeine and the vitamins riboflavin, nicotinamide, and pyridoxine in various energy drinks. Of 5 common MALDI matrices tested (alpha-cyano-4-hydroxycinnamic acid, sinapinic acid, 2,5-dihydroxybenzoic acid, dithranol, and 2',4',6'-trihydroxyacetophenone), alpha-cyano-4-hydroxycinnamic acid was found to be most suitable for analysis of high-sugar-containing energy drinks. Cetyltrimethylammonium bromide (CTAB) surfactant was used as a matrix-ion suppressor, at a matrix:surfactant mole ratio of approx. 500:1. The resulting mass spectra show very few matrix-related ions, while analyte signals were clearly observed. For comparative purposes the same analytes were identified and quantified in energy drinks by LC-ESI-MS with UV detection. Quantitatively the calibration curves of all 4 analytes showed a marked improvement when the surfactant-mediated method was used compared with traditional MALDI-TOF-MS; correlation coeff. of 0.989 (nicotinamide), 0.991 (pyridoxine), 0.983(caffeine) and 0.987 (riboflavin) were obtained. It was found that in quantification of the energy drink analytes the surfactant-mediated MALDI-TOF-MS results were comparable with those from LC analysis. In reproducibility experiments relative s.d. values ranged from 9.7 to 18.1%. Results demonstrate that this MS approach can be used as a rapid screening technique for fortified drinks.
Source : Anal Bioanal Chem 2008 vol.391(8), pp 2811 - 2818
Influence of roasting and different brewing processes on the ochratoxin A content in coffee determined by
La Pera, L.; Avellone, G.; Lo-Turco, V.; Di Bella, G.; Agozzino, P.; Dugo, G.
A rapid and reliable procedure has been developed for the determination of ochratoxin A (OTA) in green and roasted coffee. The method consists of extraction of the sample with methanol-5% aqueous sodium hydrogen carbonate/1% PEG8000 (20:80), followed by immunoaffinity column (IAC) clean-up and, finally, high-performance liquid chromatography (HPLC) determination with fluorimetric detection. Mean recoveries for green and roasted coffee spiked at different levels ranging from 94 and 105% were obtained. The limit of determination (S/N = 3) was 0.032 ng g(-1) and the precision (within-laboratory relative standard deviation) was 6%. The method described has been used to assess the influence of roasting and different brewing processes on OTA content in commercial lots of green and roasted coffee. The results provided evidence that roasting led to a significant drop on OTA levels (65-100%). Also, the way coffee is prepared affects the OTA content: brewing using a Moka Express (Italian coffee) led to a significant reduction of OTA concentration (50-75%) since hot water stays in contact with coffee for a short time. On the contrary, Turkish coffee-making (infusion for about 10 min) cause poor reduction in OTA.
Source : Food Addit Contam vol.25 (10), pp 1259 - 1265
Biosensors based on bean sprout homogenate immobilized in chitosan microspheres and silica for determination of chlorogenic acid
Moccelini, S. K.; Spinelli, A.; Cruz-Vieira, I.
Development of chlorogenic acid biosensors and their application to the analysis of coffee samples are reported. The 2 biosensors included mung bean sprout homogenate, as a source of peroxidase, immobilized in chitosan beads or silica. These immobilized enzyme preparations catalyse the oxidation of chlorogenic acid in the presence of H2O2, and square wave voltammetry is used to measure the electrochemical reduction of the oxidation product. The biosensor constructed using chitosan beads gave a linear response to chlorogenic acid at concn. in the range 4.89-320muM and had a detection limit of 0.802muM. Corresponding values for the other biosensor which used silica as immobilization support were 4.89-48.5muM and 0.852muM. For the analysis of coffee samples, recoveries of 96.5-102.6 and 91.3-115.5% were obtained with the biosensors constructed using chitosan beads and silica, respectively. Results of chlorogenic acid determinations in coffee samples using either of the biosensors agreed well with those produced using a method based on capillary electrophoresis.
Source : Enzyme and Microbial Technology 2008 vol.43 (4-5), pp 381 - 387
Investigation of ochratoxin A, B and citrinin contamination in various commercial foods
Tabata, S.; Jida, K.; Kimura, K.; Iwasaki, Y.; Nakazato, M.; Kamata, K.; Hirokado, M.
Ochratoxin A (OTA), ochratoxin B (OTB) and citrinin (CIT) in commercial foods were simultaneously determined and confirmed with HPLC and LC coupled with tandem MS (LC/MS/MS). The samples examined were made up of cereal, fruit, coffee and cocoa products. The limits of quantification (S/N <greater than or equal to>10) of OTA, OTB and CIT were 0.1 mug/kg or less. Aflatoxins (AF), deoxynivalenol (DON) and fumonisins were also surveyed. Of 157 samples examined, 44 were contaminated with OTA at levels of 0.11 to 4.0 mug/kg. At least 2 positive samples were labelled as domestic products. In most positive samples, the OTA level was low, <1 mug/kg. The highest incidence of OTA was observed in cocoa powder (10/12), followed by instant coffee (5/7), cocoa (5/8) and raisin (6/13). OTB was found in fruit and cocoa products containing relatively high levels of OTA. Co-occurrence of OTA, CIT and DON was found in cereal products, and co-occurrence of OTA and AF was found in cocoa products. Approx. 30% of naturally contaminated OTA in roasted coffee bean moved into the extract solution when brewed with paper filter.
Source : J Food Hygienics Society of Japan 2008 vol.49 (2), pp 111 - 115 (in Japanese)
Simultaneous determination of ochratoxin A, B and citrinin in foods by HPLC-FL and LC/MS/MS Source
Tabata, S.; Jida, K.; Kimura, K.; Iwasaki, Y.
Methods using HPLC with fluorescence detection (HPLC-FL) and using LC with tandem MS (LC/MS/MS) were developed for simultaneous determination of ochratoxin A (OTA), ochratoxin B (OTB) and citrinin (CIT) in cereal, fruit and coffee products. The samples were extracted with ethyl acetate under acidic conditions, then cleaned up with liquid-liquid separation. The test solutions were analysed by reverse-phase HPLC-FL and LC/MS/MS. MS acquisition was performed in positive ion mode by applying multiple reaction monitoring. Results showed that the performances of both detectors were almost equivalent. The recoveries of OTA and OTB were 87-111%, and that of CIT were 70-88%. The limits of quantification (S/N <greater than or equal to>10) of OTA, OTB and CIT was 0.1 mug/kg or less. It is concluded that these methods may be useful for the determination of the 3 mycotoxins at low levels (0.1 mug/kg).
Source : J Food Hygienics Society of Japan 2008 vol.49 (2), pp 100 - 105
Reduction of nitrous acid to nitric oxide by coffee melanoidins and enhancement of the reduction by thiocyanate: possibility of its occurrence in the stomach
Takahama, U.; Hirota, S.
Reactions of nitrous acid with freeze-dried instant coffee and its methanol-insoluble melanoidin fractions were studied at pH 2 in the presence and absence of thiocyanate (SCN-), simulating the mixture of coffee, saliva and gastric juice. Coffee contained stable radicals, and the radical concn. increased in the presence of ferricyanide and decreased in the presence of ascorbic acid. This indicates that the radical concn. was affected by the redox state of coffee and that the nature of the radical was dependent on the quinhydrone structure that might be present in the coffee melanoidins fraction. Nitrite also increased the electron spin resonance (ESR) signal intensity at pH 2, suggesting that nitrite oxidized coffee melanoidins producing nitric oxide (NO). The formation of NO could be detected from oxygen uptake due to the autoxidation of NO and using an NO-trapping agent. SCN- largely enhanced NO formation in coffee and methanol-insoluble melanoidin fractions but only slightly in a methanol-soluble fraction, and the increase accompanied the consumption of SCN-, but did not accompany the formation of a stable ESR signal. The enhancement was attributed to the reduction of NOSCN by melanoidins in methanol-insoluble fractions and the consumption was attributed to binding of SCN- to melanoidins during their oxidation by nitrous acid. The results suggest that when coffee is ingested, in addition to chlorogenic acid and its isomers, melanoidins can also react with salivary nitrite and SCN- in the gastric lumen, producing NO.
Source : J Agric Food Chem 2008 vol.56 (12), pp 4736 - 4744
COFFEE & HEALTH
Early effects of caffeinated and decaffeinated coffee on subjective state and gender
Adan, A.; Prat, G.; Fabbri, M.; Sanchez-Turet, M.
Some previous studies have demonstrated an early effect of caffeine administration on subjective state, but none of them has explored its existence after the administration of decaffeinated coffee, or the possible differences depending on the gender and circadian typology of the subjects. The aim of the present work is to investigate the early effects (10-30 min post-consumption) of a single low dose of caffeine (100 mg) and decaffeinated coffee on sleepiness, subjective activation and affect using a realistic design. The influence of gender and circadian typology is also explored. METHODS: A randomized double-blind informed placebo controlled procedure was applied to 688 healthy undergraduate volunteers, mean age 22.03+/-2.21 years, 238 men and 450 women. Measures were recorded before and after beverage consumption (10, 20 and 30 min), in two experimental sessions: morning 11:00-13:00 h or afternoon 16:00-18:00 h. RESULTS: Caffeine administration induced arousing effects (lesser somnolence and greater activation) in all post-consumption records, while the effects of decaffeinated drink were only apparent at 10 min. Caffeine effects were greater in men, and the decaffeinated beverage produced greater effects in women. Circadian typology only showed effects for time of day (morning/afternoon) related with rhythmic expression.
CONCLUSION: Future works should study more accurately the early effect of coffee beverages and the influence of gender, using other parameters which have proven to be sensitive to their administration. The effect of several caffeine doses should also be studied.
Source : Prog Neuropsychopharmacol Biol Psychiatry 2008 vol.32 (7), pp 1698 - 1703
Placebo response to caffeine improves reaction time performance in sleepy
Anderson, C.; Horne, J. A.
Caffeine is the most widely used stimulant to counteract sleepiness. However, little is known about any placebo effect of caffeine in sleepy people and the effect of suggestibility. Over a 95 min test period, and in a counterbalanced design, 16 young healthy adults underwent 3 x 30 min sessions at the psychomotor vigilance test (PVT), during an early afternoon 'dip' enhanced by a prior night's sleep restriction (5 h). On both occasions they were given a cup of a decaffeinated coffee; once when the participant was verbally primed to suggest the coffee was caffeinated (Placebo) and on the other under neutral priming (Control). There were significantly fewer lapses and shorter reaction times following Placebo, for the initial two 30 min sessions, indicating that suggestion about consuming caffeine was effective in improving performance in moderately sleepy people.
Source : Hum Psychopharmacol 2008 vol.23 (4), pp 333 - 336
Increased emotional reactivity in rats following exposure to caffeine during
Anderson, N. L.; Hughes, R. N.
From 45 to 55 days after birth, male and female rats were treated via daily intraperitoneal injections with either isotonic saline, or 15 or 30 mg/kg caffeine. When 72-82 and 112-122 days old, their activity and emotional reactivity were assessed by means of frequencies of rearing, ambulation, immobility, defecation and urination recorded in an open field, as well as their occupancy of corners and center squares of the field, and their partial emergence and latencies to fully emerge from a small darkened chamber into a brightly lit arena. Rats treated with caffeine were probably more emotionally reactive than untreated controls as suggested by more immobility and defecation and urination. There were also effects on rearing and ambulation that might have arisen from increased impulsivity. Further evidence of caffeine treatment-induced higher emotional reactivity was found in the heavier adrenal glands of a small number of 10 months-old males. This occurred in the absence of any caffeine treatment effects on spatial reference memory measured by ability to identify a novel Y-maze arm. Changes between the two testing ages in rearing and emergence latencies, and sex-dependent changes in ambulation, defecation and corner and center squares occupancy, along with immobility for 30 mg/kg caffeine-treated subjects, were discussed in the light of possible changes in emotional reactivity. Sex differences in open-field rearing and ambulation, and testing age-dependent sex differences in corner and center squares occupancy were ascribed to higher emotional reactivity in males.
Source : Neurotoxicol Teratol 2008 vol.30 (3), pp 195 - 201
The acute effects of a caffeine-containing supplement on bench press strength and time to running exhaustion
Beck, T. W.; Housh, T. J.; Malek, M. H.; Mielke, M.; Hendrix, R.
The purpose of the present study was to examine the acute effects of a caffeine-containing supplement (SUPP) on one-repetition maximum (1-RM) bench press strength and time to running exhaustion (TRE) at a velocity that corresponded to 85% of the peak oxygen uptake ([latin capital V with dot above]O2peak). The study used a double-blinded, placebo-controlled, crossover design. Thirty-one men (mean +/- SD age = 23.0 +/- 2.6 years) were randomly assigned to take either the SUPP or placebo (PLAC) first. The SUPP contained 201 mg of caffeine, and the PLAC was microcrystalline cellulose. All subjects were tested for 1-RM bench press strength and TRE at 45 minutes after taking either the SUPP or PLAC. After 1 week of rest, the subjects returned to the laboratory and ingested the opposite substance (SUPP or PLAC) from what was taken during the previous visit. The 1-RM bench press and TRE tests were then performed in the same manner as before. The results indicated that the SUPP had no effect on 1-RM bench press strength or TRE at 85% [latin capital V with dot above]O2peak. It is possible that the acute effects of caffeine are affected by differences in training status and/or the relative intensity of the exercise task. Future studies should examine these issues, in addition to testing the acute effects of various caffeine doses on performance during maximal strength, power, and aerobic activities. These findings do not, however, support the use of caffeine as an ergogenic aid in untrained to moderately trained individuals.
Source : J Strength Cond Res 2008 vol.22 (5), pp 1654 - 1658
Tea or coffee? A case study on evidence for dietary advice
Binns, C. W.; Lee, A. H.; Fraser, M. L.
The present paper explores the level of evidence required to justify giving dietary advice to the public. There are important practical differences between the development of public health nutrition guidelines and guidelines for clinical practice. While the gold standard for evidence for clinical practice guidelines is a meta-analysis of a number of randomised controlled trials, this is often unrealistic and sometimes unethical for the evaluation of public health nutrition interventions. Hence, epidemiological studies make up the bulk of evidence for nutrition guidelines. Tea and coffee are an interesting case study in relation to this issue. They are two of the most commonly consumed beverages worldwide, yet there is little dietary advice on their use. The evidence for a relationship between coffee or tea consumption and several diseases is discussed. The available studies, predominantly epidemiological, together with animal and in vitro studies, indicate that coffee and tea are both safe beverages. However, tea is the healthier option because it has a possible role in the prevention of several cancers and CVD. While the evidence for such relationships is not strong, the public will continue to drink both tea and coffee, and will continue to ask nutritionists to make recommendations. It is therefore argued that advice should be given on the best available data, as waiting for complete data to become available could have severe consequences for public health.
Source : Public Health Nutr 2008 vol.11 (11), pp 1132 - 1141
Assessing caffeine exposure in pregnant women
Boylan, S. M.; Cade, J. E.; Kirk, S. F.; Greenwood, D. C.; White, K. L.; Shires, S.; Simpson, N. A.; Wild, C.P.; Hay, A. W.
Studies on the effects of caffeine on health, while numerous, have produced inconsistent results. One of the most uncertain and controversial effects is on pregnancy outcome. Studies have produced conflicting results due to a number of methodological variations. The major challenge is the accurate assessment of caffeine intake. The aim of the present study was to explore different methods of assessing caffeine exposure in pregnant women. Twenty-four healthy pregnant women from the UK city of Leeds completed both a detailed questionnaire, the caffeine assessment tool (CAT) designed specifically to assess caffeine intake and a prospective 3 d food and drink diary. The women also provided nine saliva samples over two consecutive days for estimation of caffeine and a metabolite (paraxanthine). Caffeine intakes from the CAT and diary showed adequate agreement (intra-class correlation coefficient of 0.5). For saliva caffeine and paraxanthine measures, the between-sample variation (within the same woman) was greater than between-woman and between-day variation. However, there was still adequate agreement between these measures and the CAT. The CAT is a valuable tool that is now being used in a large prospective study investigating caffeine's role in pregnancy outcome.
Source : Br J Nutr 2008 vol.100 (4), pp 875 - 882
Insulin resistance in postmenopausal women: concurrent effects of hormone replacement therapy and coffee
Catalano, D.; Trovato, G. M.; Spadaro, D.; Martines, G. F.; Garufi, G.; Tonzuso, A.; Grasso, D.; Sciacchitano, S. G.
In postmenopausal women, an increase in insulin resistance is associated with an increased risk of diabetes, cardiovascular disease and breast cancer. Hormone replacement therapy (HRT) can reduce insulin resistance and coffee use is reported to decrease the incidence of diabetes. The aim of our study was to assess possible concurrent effects of HRT and espresso coffee intake on insulin resistance and on interdependent nutritional and clinical features. METHODS: A total of 478 healthy postmenopausal, non-diabetic women (aged 54.5 +/- 4.2 years) were studied: 360 had been on HRT for at least 2 years and 118 were not treated. Insulin resistance was assessed by a conventional homeostasis model (HOMA-IR). Results: Insulin resistance is directly related to body mass index (p < 0.0001), and not with age and blood pressure; hypertensive menopausal women have a slightly higher body mass index but the same degree of insulin resistance as normotensive women. Women on HRT show lower insulin resistance, but not lower prevalence of arterial hypertension. Coffee use is associated with a decrease in insulin resistance in non-obese women receiving HRT, but not in other subsets. CONCLUSIONS: The combination of coffee consumption and HRT could lower insulin resistance in postmenopausal women. In overweight women, greater insulin sensitivity is associated with intake of espresso coffee and not with HRT; in normal weight women, only HRT is associated with lower insulin resistance.
Source : Climacteric 2008 vol.11 (5), pp 373 - 382
Movement disorder and neuromuscular change in zebrafish embryos after exposure to Movement disorder and neuromuscular change in zebrafish embryos after exposure to
Chen, Y. H.; Huang, Y. H.; Wen, C. C.; Wang, Y. H.; Chen, W. L.; Chen, L. C.; Tsay, H. J.
Though caffeine is broadly distributed in many plants and foods, little is known about the teratogenic effects of caffeine during early embryonic development. Here, we used zebrafish as a model to test toxicity and teratogenicity since they have transparent eggs, making the organogenesis of zebrafish embryos easier to observe. When the exposure doses of caffeine were less than 150 ppm (17.5, 35, 50, 100 and 150 ppm), the zebrafish embryos exhibited no significant differences in survival rates after comparison with vehicle-control (0 ppm) group. As the exposure dosages increased, the survival rates decreased. No embryos survived after treatment with 300 ppm caffeine or higher dosages. The most evident change in embryos treated with caffeine was a shorter body length (vehicle-control: 3.26+/-0.01 mm, n=49; vs 150 ppm of caffeine: 2.67+/-0.03 mm, n=50). In addition, caffeine-treated embryos exhibited significantly reduced tactile sensitivity frequencies of touch-induced movement (vehicle-control: 9.93+/-0.77 vs 17.5-150 ppm caffeine: 5.37+/-0.52-0.10+/-0.06). Subtle changes are easily observed by staining with specific monoclonal antibodies F59, Znp1 and Zn5 to detect morphological changes in muscle fibers, primary motor axons and secondary motor axon projections, respectively. Our data show that the treatment of caffeine leads to misalignment of muscle fibers and motor neuron defects, especially secondary motor neuron axonal growth defects.
Source : Neurotoxicol Teratol 2008 vol.30 (5), pp 440 - 447
Caffeine consumption amongst British athletes following changes to the 2004 WADA prohibited list
Chester, N.; Wojek, N.
This study was undertaken to examine self-reported caffeine consumption and reasons for its use, amongst UK athletes, following its removal from the 2004 World Anti-Doping Agency (WADA) Prohibited List. A convenience sample of track and field athletes (n = 193) and cyclists (n = 287) completed a postal or Web-based questionnaire. Messages were posted on athletics and cycling club Web sites and mailing lists to direct athletes to the Web-based questionnaire. Postal questionnaires were distributed at domestic sporting events. A higher proportion of cyclists (59.9 %) compared with track and field athletes (32.6 %) consumed caffeine to enhance performance (p < 0.001). A higher proportion of elite as opposed to sub-elite athletes representing cycling (p = 0.031) and athletics (p = 0.010) used caffeine to enhance performance. Of all caffeine containing products used, coffee, energy drinks, pharmaceutical preparations and caffeinated sports supplements were most prevalent. Results revealed that amongst UK athletes, the intention to use caffeine as an ergogenic aid was high, and that use was more widespread and accepted in competitive sport, especially at elite level, when compared to recreational sport.
Source : Int J Sports Med 2008 vol.29 (6), pp 524 - 528
Caffeine does not modulate nutritive blood flow to rat gastric submucosa - a microdialysis study
Cibicek, N.; Zivna, H.; Cibicek, J.; Cermakova, E.; Vorisek, V.; Malakova, J.; Micuda, S.; Palicka, V.
Coffee irritates the gastric mucosa disrupting its barrier and increasing the risk of peptic ulcers. However, caffeine's contribution to these effects has not yet been elucidated. In this study we looked at the local effect of caffeine on the microcirculation and nitric oxide production in rats together with systemic marker of oxidative stress malondialdehyde as possible mechanisms whereby caffeine might participate in mucosal barrier impairment. Materials and Methods: Four groups of rats were anesthetized and administered as a bolus four different intraperitoneal doses of caffeine (0, 1, 10 and 50 mg kg(-1) b.wt.). The gastric submucosal microcirculation and nitric oxide production were then recorded for 2.5 hours by in situ microdialysis using the flow marker ethanol. At the completion of the experiments, plasma caffeine and malondialdehyde levels as well as morphological mucosal injury were determined. Results: There were no major differences in the macro- or microscopic pictures of the mucosa among the groups. Local microcirculatory (ethanol out/in ratio) and nitric oxide monitoring failed to demonstrate statistically significant changes as did measurement of plasma malondialdehyde in response to caffeine injections.
Conclusions: Caffeine per se seems unlikely to contribute to the gastric mucosal barrier injury associated with coffee consumption by alterations in nutritive blood flow, nitric oxide production or aggravation of systemic oxidative stress. This information is relevant for better understanding of the mechanisms involved in caffeine-mediated influences on gastric physiology in relation to the irritant effects of coffee.
Source : Biomed.Pap.Med.Fac.Univ Palacky.Olomouc.Czech Repub. 2008 vol.152 (1), pp 83 - 90
In vitro evaluation of the effect of nicotine, cotinine, and caffeine on oral microorganisms
Cogo, K.; Montan, M. F.; Bergamaschi, Cde C.; Andrade, E.; Rosalen, P. L.; Groppo, F. C.
The aim of this in vitro study was to evaluate the effects of nicotine, cotinine, and caffeine on the viability of some oral bacterial species. It also evaluated the ability of these bacteria to metabolize those substances. Single-species biofilms of Streptococcus gordonii, Porphyromonas gingivalis, or Fusobacterium nucleatum and dual-species biofilms of S. gordonii -- F. nucleatum and F. nucleatum -- P. gingivalis were grown on hydroxyapatite discs. Seven species were studied as planktonic cells, including Streptococcus oralis, Streptococcus mitis, Propionibacterium acnes, Actinomyces naeslundii, and the species mentioned above. The viability of planktonic cells and biofilms was analyzed by susceptibility tests and time-kill assays, respectively, against different concentrations of nicotine, cotinine, and caffeine. High-performance liquid chromatography was performed to quantify nicotine, cotinine, and caffeine concentrations in the culture media after the assays. Susceptibility tests and viability assays showed that nicotine, cotinine, and caffeine cannot reduce or stimulate bacterial growth. High-performance liquid chromatography results showed that nicotine, cotinine, and caffeine concentrations were not altered after bacteria exposure. These findings indicate that nicotine, cotinine, and caffeine, in the concentrations used, cannot affect significantly the growth of these oral bacterial strains. Moreover, these species do not seem to metabolize these substances.
Source : Can J Microbiol 2008 vol.54 (6), pp 501 - 508
Caffeine improves adult mice performance in the object recognition task and increases BDNF and TrkB independent on phospho-CREB immunocontent in the hippocampus
Costa, M. S.; Botton, P. H.; Mioranzza, S.; Ardais, A. P.; Moreira, J. D.; Souza, D. O.; Porciuncula, L. O.
Caffeine is one of the most psychostimulants consumed all over the world that usually presents positive effects on cognition. In this study, effects of caffeine on mice performance in the object recognition task were tested in different intertrial intervals. In addition, it was analyzed the effects of caffeine on brain derived neurotrophic factor (BDNF) and its receptor, TrkB, immunocontent to try to establish a connection between the behavioral finding and BDNF, one of the neurotrophins strictly involved in memory and learning process. CF1 mice were treated during 4 consecutive days with saline (0.9g%, i.p.) or caffeine (10mg/kg, i.p., equivalent dose corresponding to 2-3 cups of coffee). Caffeine treatment was interrupted 24h before the object recognition task analysis. In the test session performed 15min after training session, caffeine-treated mice recognized more efficiently both the familiar and the novel object. In the test session performed 90min and 24h after training session, caffeine did not change the time spent in the familiar object but increased the object recognition index, when compared to control group. Western blotting analysis of hippocampus from caffeine-treated mice revealed an increase in BDNF and TrkB immunocontent, compared to their saline-matched controls. Phospho-CREB immunocontent did not change with caffeine treatment. Our results suggest that acute treatment with caffeine improves recognition memory, and this effect may be related to an increase of the BDNF and TrkB immunocontent in the hippocampus.
Source : Neurochem Int 2008 vol.53 (3-4), pp 89 - 94
Bladder cancer, GSTs, NAT1, NAT2, SULT1A1, XRCC1, XRCC3, XPD genetic polymorphisms and coffee consumption: a case-control study
Covolo, L.; Placidi, D.; Gelatti, U.; Carta, A.; Scotto-Di-Carlo, A.; Lodetti, P.; Picciche, A.; Orizio, G.; Campagna, M.; Arici, C.; Porru, S.
The aim of the study was to investigate NAT1, NAT2, GSTM1, GSTT1, GSTP1, SULT1A1, XRCC1, XRCC3 and XPD genetic polymorphisms, coffee consumption and risk of bladder cancer (BC) through a hospital-based case-control study. The study population included 197 incident BC cases and 211 controls. The association between genetic polymorphisms, coffee drinking and BC risk was assessed by logistic regression taking into account age, education, tobacco smoking and occupational exposures to polycyclic aromatic hydrocarbons and aromatic amines. No association was found between the genetic polymorphisms investigated and BC risk according to coffee consumption apart of a significant increased BC risk among GSTP1 105-114 Val carriers heavy coffee drinkers (>3 cups/day) (OR 3.18, 95% CI 1.06¬9.55). In conclusion our findings suggest a very limited role, if any, of genetic polymorphisms investigated in modulating the BC risk in coffee drinkers.
Source : Eur J Epidemiol 2008 vol.23 (5), pp 355 - 362
Effects of acute and repeated administration of caffeine on temporal discounting in rats
Diller, J. W.; Saunders, B. T.; Anderson, K. G.
Delay to presentation is one variable that can weaken the reinforcing efficacy of an outcome in a choice situation and drugs have been shown to modify such choices. A growing body of literature has examined effects of stimulant drugs on temporal (delay) discounting, but effects of caffeine, the most widely used stimulant in the world, have not previously been assessed. In the present experiment, effects of caffeine (administered acutely and repeatedly) on temporal discounting were analyzed. Male Sprague-Dawley rats (n=7) chose between a single food pellet delivered immediately after a lever press and three food pellets delivered after a delay. The delay to the three pellets increased within each session, from 0 to 16 s. High doses of caffeine increased large-reinforcer choice relative to control conditions. With repeated caffeine exposure, percent choice for the large reinforcer decreased relative to acute administration, but was still greater than pre-drug baseline. Following withdrawal of drug administration, choice returned to levels seen during pre-drug baseline. Reintroduction of caffeine increased the percent choice for a larger, delayed reinforcer to near acute levels. The results from the present study are consistent with previous research in which stimulant drugs have decreased temporal (delay) discounting.
Source : Pharmacol Biochem Behav 2008 vol.89 (4), pp 546 - 555
Caffeine dependence in rats: Effects of exposure duration and concentration
Dingle, R. N.; Dreumont-Boudreau, S. E.; Lolordo, V. M.
Groups of rats were chronically exposed to a 1.0-g/L caffeine solution for 5, 10, 15 or 20 days. Upon removal of caffeine, rats were given brief exposure to a novel flavour CS (withdrawal CS) followed by 12 days of plain water and then brief exposure to a second flavour CS (neutral CS). Only rats exposed to 20 days of caffeine strongly preferred the neutral CS to the withdrawal CS in a 2-bottle test. In Experiment 2, groups of rats were chronically exposed to caffeine at one of four concentrations (1.0, 0.5, 0.25, or 0.125 g/L) for 21 days, after which withdrawal and neutral CSs were established. Only rats that drank the highest caffeine concentration, 1.0 g/L, preferred the neutral CS to the withdrawal CS. This suggests that long exposure to a strong caffeine solution is required in order to induce dependence in rats such that a CS associated with the withdrawal of caffeine becomes avoided.
Source : Physiol Behav 2008 vol.95 (1 -2), pp 252 - 257
Induction of CYP1A2 by heavy coffee consumption in Serbs and Swedes
Djordjevic, N.; Ghotbi, R.; Bertilsson, L.; Jankovic, S.; Aklillu, E.
OBJECTIVES: To investigate the influence of coffee consumption on CYP1A2 enzyme activity controlling for the effects of smoking and oral contraceptive (OC) use among Serbs and Swedes and to compare CYP1A2 activity between the two populations. METHODS: Data on oral contraceptive use, habitual coffee consumption and smoking habits were obtained from 100 Serbian and 149 Swedish healthy volunteers using a detailed questionnaire. CYP1A2 activity was estimated by plasma paraxanthine/caffeine (17X/137X) ratio analysed by reversed-phase HPLC after oral administration of 100 mg caffeine. RESULTS: Daily consumption of at least three cups of coffee significantly increased CYP1A2 enzyme activity in both Serbs (P=0.0002) and Swedes (P<0.0001). Among non-smokers and non-OC users, heavy coffee consumption significantly increased CYP1A2 activity in Serbs (mean difference 0.11; 95% CI of the mean difference 0.04, 0.18; P=0.003) and Swedes (mean difference 0.07; 95% CI of the mean difference 0.01, 0.12; P=0.02). Significantly higher 17X/137X ratio was detected in Serbian smokers compared to non-smokers. There was no significant gender difference in CYP1A2 activity in Serbs. Controlling for the effect of smoking, heavy coffee consumption habit and oral contraceptive use, significantly lower 17X/137X ratio was observed in Serbs than in Swedes (P=0.0003).
CONCLUSIONS: Habitual heavy coffee consumption increases CYP1A2 activity. Polycyclic aromatic hydrocarbons formed during roasting of coffee beans might partly be responsible for this effect. The reason for the observed lower CYP1A2 activity in Serbs as compared to Swedes remains to be investigated.
Source : EurJ Clin Pharmacol 2008 vol.64 (4), pp 381 - 385
Conditioned flavor avoidance as a measure of withdrawal in rats chronically exposed to a caffeine solution
Dreumont-Boudreau, S. E.; Dingle, R. N.; Alcolado, G. M.; Lolordo, V. M.
Rats were given 21 days of chronic oral caffeine. A novel flavor (Maintenance CS) was then paired with the continuation of caffeine, and a second flavor (Withdrawal CS) was paired with caffeine removal. Rats avoided the Withdrawal CS, and drank more of the Maintenance CS in a two-bottle test, suggesting that removing caffeine had induced withdrawal. The value of the Maintenance CS was investigated by comparing it to a novel flavor paired with water (Neutral CS). In a series of two-bottle tests, the Maintenance and Neutral CSs were equivalent when pitted against each other, and both were preferred to the Withdrawal CS. These results demonstrate that conditioned flavor avoidance is a useful procedure in assessing caffeine withdrawal, and by inference dependence, produced by chronic oral consumption.
Source : Physiol Behav vol.95 (1-2), pp 245 - 251
Differential effects of caffeine on the antidepressant-like effect of amitriptyline in female rat subpopulations
Enriquez-Castillo, A.; Alamilla, J.; Barral, J.; Gourbiere, S.; Flores-Serrano, A. G.; Gongora-Alfaro, J. L.; Pineda, J. C.
The interaction of caffeine (1 mg/kg) and amitriptyline (15 mg/kg) on the immobility time (IT) during Porsolt's forced swimming test (FST) was investigated in female Wistar rats. Akaike's Information Criterion indicated that the ITs recorded from 142 rats during the first day of the FST followed a bimodal distribution. Hence, the median (125.5 s) was used to classify the animals in subpopulations with low (<125.5 s, LI-rats) or high (>125.5 s, HI-rats) immobility. The paired t-test was used to compare the change of ITs between the first and second swimming sessions. Vehicle-treated animals had a significant increase of ITs during the second day of the test, either in LI-rats (77+/-12 s vs. 196+/-8 s, P<0.0001, n=6) or HI-rats (150+/-8 s vs. 201+/-10 s, P<0.02, n=6). In LI-rats amitriptyline only prevented the increase of ITs during the second session (74+/-27 s vs. 97+/-42 s, n=12), whereas in HI-rats the antidepressant produced a significant decrease of ITs during the second session (161+/-22 s vs. 118+/-32 s, n=7, P<0.02). While caffeine alone prevented the increase of ITs in both groups, the methylxanthine abolished the effect of amitriptyline in HI-rats (165+/-23 s vs. 165+/-46 s, n=9), leaving the antidepressant action unaffected in LI-rats (87+/-23 s vs. 96+/-58 s, n=9). These results suggest that the anti-immobility effect of amitriptyline in HI-rats is mediated in part by endogenous adenosine.
Source : Physiol Behav 2008 vol.94 (3), pp 501 - 509
Caffeine inhibits suicidal erythrocyte death
Floride, E.; Foller, M.; Ritter, M.; Lang, F.
Eryptosis, the suicidal death of erythrocytes, is characterized by cell shrinkage and by cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Eryptosis is triggered by several stress conditions including isotonic cell shrinkage (Cl(-) removal) and energy depletion (glucose removal). Both are effective through an increase in the cytosolic Ca(2+) concentration. Phosphatidylserine-exposing erythrocytes are cleared from circulating blood. Enhanced eryptosis thus leads to anemia. Accordingly, drugs interfering with eryptosis may prove useful in the treatment of anemia. The present study explored, whether caffeine interferes with eryptosis. Erythrocyte phosphatidylserine exposure was estimated from annexin V-binding, cell volume from forward scatter and cytosolic Ca(2+) activity from Fluo3 fluorescence. Under control conditions, eryptosis affected less than 5% of the erythrocytes and was not significantly modified by the presence of caffeine (50-500 microM).Glucose depletion (for 48 hours) significantly increased Fluo3 fluorescence and annexin V-binding and decreased forward scatter, effects partially reversed by caffeine (500 microM). Low Cl(-) solution (Cl(-) exchanged by gluconate for 48 hours) similarly increased annexin V-binding and decreased forward scatter, effects again reversed by caffeine (50-500 microM). In conclusion, caffeine inhibits Ca(2+) entry following glucose depletion and thuscounteracts eryptosis during isotonic cell shrinkage and energy depletion.
Source : Cell Physiol Biochem 2008 vol.22 (1-4), pp 253 - 260
A perception on health benefits of coffee
George, S. E.; Kulathooran, Ramalakshmi; Mohan-Rao, L. J.
The physiological effects of coffee on the human body are reviewed. Aspects considered include; antioxidative activity; anticarcinogenic activity; mutagenic and antimutagenic effects; effects on central nervous system; mechanism of pharmacological action of caffeine; effects on human behaviour; reproductive and developmental potential; effect on homocysteine; effects on bone health; effects of coffee on the cardiovascular system; effects on cholesterol, triglycerides and lipoprotein; and other health effects.
Source : Critical Reviews in Food Science and Nutrition 2008 vo/.48 (5), pp 464 - 486
Caffeine supplementation and multiple sprint running performance
Glaister, M.; Howatson, G.; Abraham, C. S.; Lockey, R. A.; Goodwin, J. E.; Foley, P.; McInnes, G.
The aim of this study was to examine the effects of caffeine supplementation on multiple sprint running performance. METHODS: Using a randomized double-blind research design, 21 physically active men ingested a gelatin capsule containing either caffeine (5 mg x kg(-1) body mass) or placebo (maltodextrin) 1 h before completing an indoor multiple sprint running trial (12 x 30 m; repeated at 35-s intervals). Venous blood samples were drawn to evaluate plasma caffeine and primary metabolite concentrations. Sprint times were recorded via twin-beam photocells, and earlobe blood samples were drawn to evaluate pretest and posttest lactate concentrations. Heart rate was monitored continuously throughout the tests, with RPE recorded after every third sprint. RESULTS: Relative to placebo, caffeine supplementation resulted in a 0.06-s (1.4%) reduction in fastest sprint time (95% likely range = 0.04-0.09 s), which corresponded with a 1.2% increase in fatigue (95% likely range = 0.3-2.2%). Caffeine supplementation also resulted in a 3.4-bpm increase in mean heart rate (95% likely range = 0.1-6.6 bpm) and elevations in pretest (+0.7 mmol x L(-1); 95% likely range = 0.1-1.3 mmol x L(-1)) and posttest (+1.8 mmol x L(-1); 95% likely range = 0.3-3.2 mmol x L(-1)) blood lactate concentrations. In contrast, there was no significant effect of caffeine supplementation on RPE. CONCLUSION: Although the effect of recovery duration on caffeine-induced responses to multiple sprint work requires further investigation, the results of the present study show that caffeine has ergogenic properties with the potential to benefit performance in both single and multiple sprint sports.
Source : Med Sci Sports Exerc 2008 vol.40 (10), pp 1835 - 1840
Antioxidant activity and protective effects of green and dark coffee components against human low density lipoprotein oxidation
Gomez-Ruiz, J. A.; Ames, J. M.; Leake, D. S.
The in vitro antioxidative activity and protective effects against human low density lipoprotein (LDL) oxidation of coffees prepared using different degrees of roasting were evaluated. Coffees with the highest contents of brown pigments (dark coffee) showed the highest peroxyl radical scavenging activities. These coffees also protected human LDL against oxidation, although green coffee extracts offered more protection. In a different experiment, coffee extracts were incubated with human plasma prior to isolation of LDL particles. This showed, for the first time, that incubation of plasma with dark but not green coffee extracts protected LDL against oxidation by Cu or by the thermolabile azo compound, AAPH. Antioxidants in the dark coffee extracts must therefore have become associated with the LDL particles. Brown compounds, especially those derived from the Maillard reaction, are the compounds most likely to be responsible for this activity.
Source : Eur Food Res Technol 2008 vol.227 (4), pp 1017 - 1024
Paraxanthine, the Primary Metabolite of Caffeine, Provides Protection against Dopaminergic Cell Death via Stimulation of Ryanodine Receptor Channels
Guerreiro, S.; Toulorge, D.; Hirsch, E.; Marien, M.; Sokoloff, P.; Michel, P. P.
Epidemiological evidence suggests that caffeine or its metabolites reduce the risk of developing Parkinson's disease, possibly by protecting dopaminergic neurons, but the underlying mechanism is not clearly understood. Here, we show that the primary metabolite of caffeine, paraxanthine (PX; 1, 7-dimethylxanthine), was strongly protective against neurodegeneration and loss of synaptic function in a culture system of selective dopaminergic cell death. In contrast, caffeine itself afforded only marginal protection. The survival effect of PX was highly specific to dopaminergic neurons and independent of glial cell line-derived neurotrophic factor (GDNF). Nevertheless, PX had the potential to rescue dopaminergic neurons that had matured initially with and were then deprived of GDNF. The protective effect of PX was not mediated by blockade of adenosine receptors or by elevation of intracellular cAMP levels, two pharmacological effects typical of methylxanthine derivatives. Instead, it was attributable to a moderate increase in free cytosolic calcium via the activation of reticulum endoplasmic ryanodine receptor (RyR) channels. Consistent with these observations, PX and also ryanodine, the preferential agonist of RyRs, were protective in an unrelated paradigm of mitochondrial toxin-induced dopaminergic cell death. In conclusion, our data suggest that PX has a neuroprotective potential for diseased dopaminergic neurons.
Source : Mol Pharmacol 2008 vo/.74 (4), pp 980 - 989
Effects of coffee bean aroma on the rat brain stressed by sleep deprivation: a selected transcript- and 2D gel-based proteome analysis
Han, Seok Seo; Hirano, M.; Shibato, J.; Randeep, Rakwal; In, Kyeong Hwang; Masuo, Y.
The aim of this study was 2-fold: (i) to demonstrate influences of roasted coffee bean aroma on rat brain functions by using the transcriptomics and proteomics approaches and (ii) to evaluate the impact of roasted coffee bean aroma on stress induced by sleep deprivation. The aroma of the roasted coffee beans was administered to 4 groups of adult male Wistar rats: 1, control group; 2, 24 h sleep deprivation-induced stress group (the stress group); 3, coffee aroma-exposed group without stress (the coffee group); and 4, the stress with coffee aroma group (the stress with coffee group). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of some known genes responsive to aroma or stress was
performed using total RNA from these 4 groups. A total of 17 selected genes of the coffee were differently expressed over the control. Additionally, the expression levels of 13 genes were different between the stress group and the stress with coffee group: Up-regulation was found for 11 genes, and down-regulation was seen for 2 genes in the stress with coffee group. We also looked to changes in protein profiles in these 4 samples using two-dimensional (2D) gel electrophoresis; 25 differently expressed gel spots were detected on 2D gels stained by silver nitrate. Out of these, a total of 9 proteins were identified by MS. Identified proteins belonged to 5 functional categories: antioxidant; protein fate; cell rescue, defense and virulence; cellular communication/signal transduction mechanism; and energy metabolism. Among the differentially expressed genes and proteins between the stress and the stress with coffee group, NGFR, trkC, GIR, thiol-specific antioxidant protein, and heat shock 70 kDa protein 5 are known to have antioxidant or antistress functions. In conclusion, the roasted coffee bean aroma changes the mRNA and protein expression levels of the rat brain, providing for the 1st time clues to the potential antioxidant or stress relaxation activities of the coffee bean aroma.
Source : J Agric Food Chem 2008 vol.56 (12), pp 4665 - 4673
Caffeine improves physical and cognitive performance during exhaustive exercise
Hogervorst, E.; Bandelow, S.; Schmitt, J.; Jentjens, R.; Oliveira, M.; Allgrove, J.; Carter, T.; Gleeson, M.
PURPOSE: To examine the effects of ingesting a performance bar, containing caffeine, before and during cycling exercise on physical and cognitive performance. METHODS: Twenty-four well-trained cyclists consumed the products [a performance bar containing 45 g of carbohydrate and 100 mg of caffeine (CAF), an isocaloric noncaffeine performance bar (CHO), or 300 mL of placebo beverage (BEV)] immediately before performing a 2.5-h exercise at 60% VO2max followed by a time to exhaustion trial (T2EX) at 75% VO2max. Additional products were taken after 55 and 115 min of exercise. Cognitive function measures (computerized Stroop and Rapid Visual Information Processing tests) were performed before exercise and while cycling after 70 and 140 min of exercise and again 5 min after completing the T2EX ride. RESULTS: Participants were significantly faster after CAF when compared with CHO on both the computerized complex information processing tests, particularly after 140 min and after the T2EX ride (P < 0.001). On the BEV trial, performance was significantly slower than after both other treatments (P < 0.0001). There were no speed-accuracy tradeoffs (P > 0.10). T2EX was longer after CAF consumption compared with both CHO and BEV trials (P < 0.05), and T2EX was longer after CHO than after BEV (P < 0.05). No differences were found in the ratings of perceived exertion, mean heart rate, and relative exercise intensity (% VO2max; P > 0.05).
CONCLUSION: Caffeine in a performance bar can significantly improve endurance performance and complex cognitive ability during and after exercise. These effects may be salient for sports performance in which concentration plays a major role.
Source : Med Sci Sports Exerc 2008 vol.40 (10), pp 1841 - 1851
Caffeine stimulates cytochrome oxidase expression and activity in the striatum in a sexually dimorphic manner
Jones, F. S.; Jing, J.; Stonehouse, A. H.; Stevens, A.; Edelman, G. M.
Epidemiological studies indicate that caffeine consumption reduces the risk of Parkinson's disease (PD) in men, and antagonists of the adenosine 2A receptor ameliorate the motor symptoms of PD. These findings motivated us to identify proteins whose expression is regulated by caffeine in a sexually dimorphic manner. Using mass spectroscopy, we found that Cox7c, a nuclear-encoded subunit of the mitochondrial enzyme cytochrome oxidase, is up-regulated in the striatum of male but not female mice after receiving a single dose of caffeine. The expression of two other Cox subunits, Cox1 and Cox4, was also stimulated by caffeine in a male-specific fashion. This up-regulation of Cox subunits by caffeine was accompanied by an increase in Cox enzyme activity in the male striatum. Caffeine-induced stimulation of Cox expression and activity were reproduced using the adenosine 2A receptor (A2AR)-specific antagonist 5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-epsilon]-1,2,4-triazolo[1,5-c]pyrimidine (SCH58261), and coadministration of the A2AR-specific agonist 2-[p-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamidoadenosine (CGS21680) counteracted the elevation of Cox expression and activity by caffeine. Caffeine also increased Cox activity in PC-12 cells. In contrast, small interfering RNA (siRNA) knockdown of Cox7c expression in PC-12 cells blunted Cox activity, and this was counteracted by caffeine treatment. Caffeine was also found to increase Cox7c mRNA expression in the striatum and in PC-12 cells. This occurred at the level of transcription and was mediated by a segment of the Cox7c promoter. Overall, these findings indicate that cytochrome oxidase is a metabolic target of caffeine and that stimulation of Cox activity by caffeine via blockade of A2AR signaling may be an important mechanism underlying the therapeutic benefits of caffeine in PD.
Source : Mol Pharmacol 2008 vol.74 (3), pp 673 - 684
Protective effect of caffeine on streptozotocin-induced beta-cell damage in rats
Kagami, K.; Morita, H.; Onda, K.; Hirano, T.; Oka, K.
Many epidemiological studies have shown that coffee consumption reduces the risk of type 2 diabetes mellitus (T2D), although the reasons as to why remain unclear. In this study we investigated the effect of caffeine on pancreatic beta-cell damage in rats using the diabetogenic agent, streptozotocin (STZ). Wistar rats were given intraperitoneal injections of saline or caffeine (10, 50 or 100 mg kg(-1)). After 15 min, the rats were injected with a citrate buffer or 65 mg kg(-1) STZ. Three days after injection, an oral glucose tolerance test (OGTT) was performed on the rats. Furthermore, three days after the OGTT, the pancreas was isolated and homogenized, followed by determination of insulin content. STZ treatment significantly increased the plasma glucose level compared with the control at all times during the OGTT, which was significantly diminished by caffeine pretreatment at all doses. STZ treatment significantly decreased the plasma insulin level, however, which was not recovered by caffeine pretreatment. Pancreatic insulin content was significantly reduced by STZ treatment compared with the control, which was significantly recovered by caffeine pretreatment at a dose of 100 mg kg(-1) (P < 0.01). We showed that caffeine protects pancreatic beta-cells against STZ toxicity. Further investigation will be required to understand the protective effect of caffeine against beta-cell destruction in T2D.
Source : J Pharm Pharmacol 2008 vol.60 (9), pp 1161 - 1165
Caffeine yields aneuploidy through asymmetrical cell division caused by misalignment of chromosomes
Katsuki, Y.; Nakada, S.; Yokoyama, T.; Imoto, I.; Inazawa, J.; Nagasawa, M.; Mizutani, S.
Aneuploidy has been implicated as an important step leading to various neoplasias. Although genetic factors that block aneuploidy have been the subject of intense interest, the impact of pharmacological and environmental substances on the development of aneuploidy has not been studied. Here, we show that caffeine induces aneuploidy through asymmetrical cell division. Mitotic exits of HeLa, U2OS, and primary fibroblast cells were significantly delayed by 10 mmol/L caffeine. Most caffeine-treated mitotic cells showed misalignment of chromosomes at the metaphase plates, and were arrested at prometaphase. Mitoticarrest deficient 2 (MAD2) depletion rescued the caffeine-induced delay of mitotic exit, indicating that caffeine-induced prolongation of mitosis was caused by activation of a MAD2-dependent spindle checkpoint. Enumeration of centromeres by fluorescence in situ hybridization revealed that cell division in the presence of caffeine was not symmetrical and resulted in aneuploid cell production. Most of these cells survived and underwent DNA synthesis. Our findings reveal a novel pharmacological effect of a high concentration of caffeine on genomic stability in dividing cells.
Source : Cancer Sci 2008 vol.99 (8), pp 1539 - 1545
L-Theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance
Kelly, S. P.; Gomez-Ramirez, M.; Montesi, J. L.; Foxe, J. J.
Recent neuropharmacological research has suggested that certain constituents of tea may have modulatory effects on brain state. The bulk of this research has focused on either L-theanine or caffeine ingested alone (mostly the latter) and has been limited to behavioral testing, subjective rating, or neurophysiological assessments during resting. Here, we investigated the effects of both L-theanine and
caffeine, ingested separately or together, on behavioral and electrophysiological indices of tonic (background) and phasic (event-related) visuospatial attentional deployment. Subjects underwent 4 d of testing, ingesting either placebo, 100 mg of L-theanine, 50 mg of caffeine, or these treatments combined. The task involved cued shifts of attention to the left or right visual hemifield in anticipation of an imperative stimulus requiring discrimination. In addition to behavioral measures, we examined overall, tonic attentional focus as well as phasic, cue-dependent anticipatory attentional biasing, as indexed by scalp-recorded alpha-band (8-14 Hz) activity. We found an increase in hit rate and target discriminability (d') for the combined treatment relative to placebo, and an increase in d' but not hit rate for caffeine alone, whereas no effects were detected for L-theanine alone. Electrophysiological results did not show increased differential biasing in phasic alpha across hemifields but showed lower overall tonic alpha power in the combined treatment, similar to previous findings at a larger dosage of L-theanine alone. This may signify a more generalized tonic deployment of attentional resources to the visual modality and may underlie the facilitated behavioral performance on the combined ingestion of these 2 major constituents of tea.
Source : J Nutrition 2008 vol. 138 (8S-I), pp 1572S - 1577S
The cumulative effect of coffee and a mental stress task on heart rate, blood pressure, and mental
Kennedy, M. D.; Galloway, A. V.; Dickau, L. J.; Hudson, M. K.
Most North American workers drink coffee throughout their workday, although the cumulative effect of job stress and coffee is not well known. Research has shown that coffee affects the cardiovascular system and mental alertness primarily through the active ingredient caffeine; however, the dose of caffeine used in these studies is greater than a normal cup of coffee. In addition, these changes have been mostly determined in male caffeine-habituated consumers. Therefore, this study examined the effect of a normal cup of coffee on the cardiovascular and mental alertness response both before and after a mental stress task in 10 caffeine-naive (23 ± 5.0 years) and 10 caffeine-habituated (25 ± 6 years) females. Blood pressure, heart rate, and mental alertness were taken at baseline (before coffee), 50 minutes after finishing coffee and immediately after a 9-minute mental stress task. The volume of coffee ingested for a 15-minute period was 350 mL (12 oz), which is equivalent to 140 mg of caffeine. The combined effect of coffee and mental stress significantly decreased diastolic blood pressure (DELTA8 mm Hg) and increased heart rate (DELTA6 beats per minute) and mental alertness (DELTA67.3%) in caffeine-naive and caffeine-habituated females, whereas systolic blood pressure (DELTA10.3 mm Hg) only increased in the caffeine-naive participants. Our results indicate that a normal cup of coffee can effect changes in blood pressure and mental alertness and that mental stress may alter the magnitude of change; however, the transient increase in systolic blood pressure after drinking coffee in caffeine-naive participants requires further investigation.
Source : Nutrition Research 2008 vol.28 (9), pp 609 - 614
Case-control study of coffee consumption and the risk of endometrial endometrioid adenocarcinoma
Koizumi, T.; Nakaya, N.; Okamura, C.; Sato, Y.; Shimazu, T.; Nagase, S.; Niikura, H.; Kuriyama, S.; Tase,
T.; Ito, K.; Tsubono, Y.; Okamura, K.; Yaegashi, N.; Tsuji, I.
This study examined the association between coffee consumption and the risk of endometrial endometrioid adenocarcinoma (EEA) in Japan by a case-control design. The cases consisted of 107 women less than 80 years of age from two medical centers who had been histopathologically diagnosed to have EEA. The controls, selected from the participants of a cancer-screening program, were 214 women, with two controls selected for each case (matched for age and for area of residence). A self-administered questionnaire containing questions to determine dietary and beverage consumption, as well as reproductive history, was distributed to the cases and controls. Conditional logistic regression analysis was used to estimate the odds ratio (OR) of EEA for three levels of coffee consumption with adjustment for potential confounding factors. The multivariate-adjusted OR of EEA for individuals in the highest tertile of coffee consumption (2 to 3 cups or more/day) was 0.4 [95% confidence interval (CI), 0.2-0.9], and that of cases in the intermediate tertile (5 to 6 times/week-1 cup/day) was 0.6 (95% CI, 0.3-1.2), relative to the individuals in the lowest tertile of coffee consumption (3 to 4 times or less/week) (P for trend=0.014). The above association was observed in postmenopausal women (P for trend=0.016), but not in premenopausal women (P for trend=0.90). This study thus revealed an inverse dose-response relationship between coffee consumption and the risk of EEA, and its strong association in postmenopausal women but not in premenopausal women.
Source : Eur J Cancer Prev 2008 vol.17 (4), pp 358 - 363
Caffeine induces Ca(2+) release by reducing the threshold for luminal Ca(2+) activation of the ryanodine receptor
Kong, H.; Jones, P. P.; Koop, A.; Zhang, L.; Duff, H. J.; Chen, S. R.
Caffeine has long been used as a pharmacological probe for studying RyR (ryanodine receptor)-mediated Ca(2+) release and cardiac arrhythmias. However, the precise mechanism by which caffeine activates RyRs is elusive. In the present study, we investigated the effects of caffeine on spontaneous Ca(2+) release and on the response of single RyR2 (cardiac RyR) channels to luminal or cytosolic Ca(2+). We found that HEK-293 cells (human embryonic kidney cells) expressing RyR2 displayed partial or 'quantal' Ca(2+) release in response to repetitive additions of submaximal concentrations of caffeine. This quantal Ca(2+) release was abolished by ryanodine. Monitoring of endoplasmic reticulum luminal Ca(2+) revealed that caffeine reduced the luminal Ca(2+) threshold at which spontaneous Ca(2+) release occurs. Interestingly, spontaneous Ca(2+) release in the form of Ca(2+) oscillations persisted in the presence of 10 mM caffeine, and was diminished by ryanodine, demonstrating that unlike ryanodine, caffeine, even at high concentrations, does not hold the channel open. At the single-channel level, caffeine markedly reduced the threshold for luminal Ca(2+) activation, but had little effect on the threshold for cytosolic Ca(2+) activation, indicating that the major action of caffeine is to reduce the luminal, but not the cytosolic, Ca(2+) activation threshold. Furthermore, as with caffeine, the clinically relevant, pro-arrhythmic methylxanthines aminophylline and theophylline potentiated luminal Ca(2+) activation of RyR2, and increased the propensity for spontaneous Ca(2+) release, mimicking the effects of disease-linked RyR2 mutations. Collectively, our results demonstrate that caffeine triggers Ca(2+) release by reducing the threshold for luminal Ca(2+) activation of RyR2, and suggest that disease-linked RyR2 mutations and RyR2-interacting pro-arrhythmic agents may share the same arrhythmogenic mechanism.
Source : Biochem J 2008 vol.414 (3), pp 441 - 452
Cancer and liver cancer prevention: is it a fact or just a potential?
La Vecchia, C.
No abstract
Source : Hepatology 2008 vol.48 (1), pp 7 - 9
Caffeine challenge in patients with panic disorder: baseline differences between those who panic and those who do not
Masdrakis, V. G.; Papakostas, Y. G.; Vaidakis, N.; Papageorgiou, C.; Pehlivanidis, A.
A proportion of patients with panic disorder (PD) display an increased sensitivity to the anxiogenic/panicogenic properties of caffeine. The aim of this study is to identify probable baseline differences between PD patients who panic and those who do not, after caffeine administration. In a randomized, double-blind, cross-over experiment performed in two occasions 3-7 days apart, 200 and 400 mg of caffeine, respectively, were administered in a coffee form to 23 patients with PD with or without Agoraphobia. Evaluations included the State-Trait Anxiety Inventory, the DSM-IV 'panic attack' symptoms (visual analogue scale form), the Symptom Checklist-90-Revised (SCL-90-R), as well as breath-holding (BH) duration, heartbeat perception accuracy and heart rate. Only those patients who did not present a panic attack after both challenges ('no panic group', N=14, 66.7%), and those who presented a panic attack after at least one challenge ('panic group', n=7, 33.3%) were included in the analysis. The panickers, compared to the non-panickers, presented at baseline: significantly higher total score of the SCL-90-R; significantly higher scores on all the SCL-90-R clusters of symptoms, except that of 'paranoid ideation'; significantly lower BH duration. The present preliminary findings indicate that PD patients who panic after a 200 mg or a 400 mg caffeine challenge, compared to the PD patients who do not panic after both of these challenges, may present at baseline significantly higher non-specific general psychopathology-as reflected in the SCL-90-R-and significantly shorter BH duration.
Source : Depress Anxiety 2008 vol.25 (9), pp E72 - E79
Hospitalization for caffeine abuse is associated with abuse of other pharmaceutical products
McCarthy, D. M.; Mycyk, M. B.; Deslauriers, C. A.
The aim of this study was to examine the characteristics and outcomes of patients seeking treatment for abuse of supplemental caffeine. METHODS: This was a 3-year analysis conducted of all consecutive cases involving caffeine abuse in patients 10 years and older reported to a regional poison center. Excluded were suicide attempts, therapeutic errors, and cases involving only a coffee or tea product. RESULTS: Two hundred fifty-four cases met inclusion criteria. Mean age was 20.5 years, 50% were women. Caffeine was in the form of a nondietary medication in 201 cases, a dietary supplement in 35 cases, and a caffeine-enhanced beverage in 35 cases. Caffeine was abused alone in 174 (68%), with alcohol in 7, illegal drugs in 6 cases, and with other pharmaceutical products in 81 (29%) cases. Thirty-four patients (13% of total) were hospitalized for medical complications from caffeine. Only concomitant abuse of other pharmaceutical products was associated with hospitalization (odds ratio, 3.8; 95% CI, 1.8-8.8; P = .0004).
CONCLUSION: In this cohort, supplemental caffeine was abused primarily by young adults. Concomitant recreational abuse of other pharmaceuticals was associated with hospitalization and warrants further investigation.
Source : Am J Emerg Med 2008 vol.26 (7), pp 799 - 802
Effects of caffeine on alertness as measured by infrared reflectance oculography
Michael, N.; Johns, M.; Owen, C.; Patterson, J.
Caffeine is a well-known stimulant that can be used to increase alertness and performance especially in low arousal situations such as monotonous highway driving or after sleep deprivation. The effects of caffeine in rested, alert, participants are less clear, and this may be attributable to difficulties in objectively assessing small changes in alertness. OBJECTIVES: The present study examined the effects of caffeine in non-sleep-deprived participants with methods that have previously been shown to be sensitive to changes in alertness. In order to avoid confounding results, low, or non-users of caffeine, were sought as participants. MATERIALS AND METHODS: Twelve subjects participated in a within-subjects double-blind placebo-controlled design study and were administered either a capsule containing 200 mg of caffeine or placebo on two separate days. Ten-minute long tests of vigilance were performed at baseline and then at 30, 60, 120, 180, and 240 min after swallowing the capsule. During vigilance tests, eye blink variables were measured using infrared reflectance oculography and converted into a drowsiness score, Johns Drowsiness Scale (JDS). RESULTS: Caffeine significantly reduced JDS scores (drowsiness) and reaction times, and these changes persisted for 3 to 4 h. Self reports of sleepiness were not as sensitive, with Karolinska Sleepiness Scale scores only being significantly lower in the caffeine compared to placebo condition at 30 min post capsule administration.
CONCLUSIONS: The results demonstrated that despite being well rested, administration of caffeine significantly increased alertness and enhanced performance, and these changes were able to be detected with the JDS.
Source : Psychopharmacology (Berl) 2008 vol.200 (2), pp 255 - 260
Caffeinated coffee consumption impairs blood glucose homeostasis in response to high and low glycemic index meals in healthy men
Moisey, L. L.; Kacker, S.; Bickerton, A. C.; Robinson, L. E.; Graham, T. E.
The ingestion of caffeine (5 mg/kg body weight) and a 75-g oral glucose load has been shown to elicit an acute insulin-insensitive environment in healthy and obese individuals and in those with type 2 diabetes. OBJECTIVE: In this study we investigated whether a similar impairment in blood glucose management exists when coffee and foods typical of a Western diet were used in a similar protocol. DESIGN: Ten healthy men underwent 4 trials in a randomized order. They ingested caffeinated (5 mg/kg) coffee (CC) or the same volume of decaffeinated coffee (DC) followed 1 h later by either a high or low glycemic index (GI) cereal (providing 75 g of carbohydrate) mixed meal tolerance test. RESULTS: CC with the high GI meal resulted in 147%, 29%, and 40% greater areas under the curve for glucose (P < 0.001), insulin (NS), and C-peptide (P < 0.001), respectively, compared with the values for DC. Similarly, with the low GI treatment, CC elicited 216%, 44%, and 36% greater areas under the curve for glucose (P < 0.001), insulin (P < 0.01), and C-peptide (P < 0.01), respectively. Insulin sensitivity was significantly reduced (40%) with the high GI treatment after CC was ingested compared with DC; with the low GI treatment, CC ingestion resulted in a 29% decrease in insulin sensitivity, although this difference was not significant. CONCLUSION: The ingestion of CC with either a high or low GI meal significantly impairs acute blood glucose management and insulin sensitivity compared with ingestion of DC. Future investigations are warranted to determine whether CC is a risk factor for insulin resistance.
Source : Am J Clin Nutr 2008 vol.87 (5), pp 1254 - 1261
Neonatal caffeine induces sex-specific developmental plasticity of the hypoxic respiratory chemoreflex in adult rats
Montandon, G.; Bairam, A.; Kinkead, R.
Caffeine is widely used to treat apneas of prematurity during the neonatal period; however, the potential consequences of administering a neonatal caffeine treatment (NCT) during a critical period for respiratory control development are unknown. The present study therefore determined whether NCT in rats alters the hypoxic respiratory chemoreflex measured at adulthood. Newborn rats received either caffeine (15 mg/kg) or water (control) each day from postnatal day 3 to 12. The ventilatory response to a hypoxic challenge (inspired O(2) fraction = 0.12) was first evaluated in awake adult female and male rats using whole body plethysmography. Results showed that NCT increased the initial phase of the breathing frequency response to hypoxia in males only. This result was confirmed in anesthetized and artificially ventilated adult male rats where NCT also increased the phrenic burst frequency response to hypoxia. RT-PCR assessment of mRNA encoding for adenosine A(1A) and A(2A) receptors, dopamine D(2) receptors, and tyrosine hydroxylase in the rat carotid bodies showed that NCT enhanced mRNA expression levels of adenosine A(2A), dopamine D(2) receptors, and tyrosine hydroxylase of males but not females. Subsequent experiments on awake male rats showed that injection of the adenosine A(2A) receptor antagonist ZM2413855 (1 mg/kg ip) before ventilatory measurements abolished, in NCT rats, the enhanced respiratory frequency response observed during the early phase of hypoxia. We propose that NCT elicits a sex-specific increase in the hypoxic respiratory chemoreflex, which is related, at least partially, to an enhancement in adenosine A(2A) receptors in the rat carotid body.
Source : Am J Physiol Regul Integr Comp Physiol 2008 vol.295 (3), pp R922 - R934
The combined effects of L-theanine and caffeine on cognitive performance and mood
Owen, G. N.; Parnell, H.; De Bruin, E. A.; Rycroft, J. A.
The aim of this study was to compare 50 mg caffeine, with and without 100 mg L-theanine, on cognition and mood in healthy volunteers. The effects of these treatments on word recognition, rapid visual information processing, critical flicker fusion threshold, attention switching and mood were compared to placebo in 27 participants. Performance was measured at baseline and again 60 min and 90 min after each treatment (separated by a 7-day washout). Caffeine improved subjective alertness at 60 min and accuracy on the attention-switching task at 90 min. The L-theanine and caffeine combination improved both speed and accuracy of performance of the attention-switching task at 60 min, and reduced susceptibility to distracting information in the memory task at both 60 min and 90 min. These results replicate previous evidence which suggests that L-theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks.
Source : Nutr Neurosci 2008 vol.11 (4), pp 193 - 198
The effect of caffeine on retrobulbar hemodynamics
Ozkan, B.; Yuksel, N.; Anik, Y.; Altintas, O.; Demirci, A.; Caglar, Y.
BACKGROUND: To investigate the acute effect of caffeine on intraocular pressure and retrobulbar blood flow velocity. METHODS: In this randomized, double-masked, placebo-controlled, prospective study, we examined the effects of single 300-mg oral administration of caffeine on retrobulbar arteries' hemodynamics by using color Doppler ultrasonography imaging in healthy human volunteers. The subjects were divided into two groups; group 1 received a 300-mg caffeine tablet and group 2 received placebo. Measurements were obtained in two eyes at baseline, and 1 hr after acute ingestion of caffeine. Blood pressure, pulse rate, and intraocular pressure were monitored. RESULTS: When compared with placebo, no significant change in mean blood pressure or intraocular pressure was observed after administration of caffeine. No significant differences were detected in the peak systolic and end diastolic velocities of retrobulbar arteries, compared with baseline values. Resistive index of ophthalmic, central
retinal, and short posterior nasal ciliary artery were significantly increased after oral application of caffeine in group 1 (p<0.05).
CONCLUSION: The vascular resistance of the retrobulbar vessels appears to be altered by caffeine consumption. Further studies are needed to investigate the effects of caffeine on hemodynamics in patients with glaucoma.
Source : Curr Eye Res 2008 vol.33 (9), pp 804 - 809
High rates of muscle glycogen resynthesis after exhaustive exercise when carbohydrate is coingested with caffeine
Pedersen, D. J.; Lessard, S. J.; Coffey, V. G.; Churchley, E. G.; Wootton, A. M.; Ng, T.; Watt, M. J.; Hawley, J. A.
We determined the effect of coingestion of caffeine (Caff) with carbohydrate (CHO) on rates of muscle glycogen resynthesis during recovery from exhaustive exercise in seven trained subjects who completed two experimental trials in a randomized, double-blind crossover design. The evening before an experiment subjects performed intermittent exhaustive cycling and then consumed a low-CHO meal. The next morning subjects rode until volitional fatigue. On completion of this ride subjects consumed either CHO [4 g/kg body mass (BM)] or the same amount of CHO + Caff (8 mg/kg BM) during 4 h of passive recovery. Muscle biopsies and blood samples were taken at regular intervals throughout recovery. Muscle glycogen levels were similar at exhaustion [ approximately 75 mmol/kg dry wt (dw)] and increased by a similar amount ( approximately 80%) after 1 h of recovery (133 +/- 37.8 vs. 149 +/- 48 mmol/kg dw for CHO and Caff, respectively). After 4 h of recovery Caff resulted in higher glycogen accumulation (313 +/-69 vs. 234 +/- 50 mmol/kg dw, P < 0.001). Accordingly, the overall rate of resynthesis for the 4-h recovery period was 66% higher in Caff compared with CHO (57.7 +/- 18.5 vs. 38.0 +/- 7.7 mmol x kg dw(-1) x h(-1), P < 0.05). After 1 h of recovery plasma Caff levels had increased to 31 +/- 11 microM (P < 0.001) and at the end of the recovery reached 77 +/- 11 microM (P < 0.001) with Caff. Phosphorylation of CaMK(Thr286) was similar after exercise and after 1 h of recovery, but after 4 h CaMK(Thr286) phosphorylation was higher in Caff than CHO (P < 0.05). Phosphorylation of AMP-activated protein kinase (AMPK)(Thr172) and Akt(Ser473) was similar for both treatments at all time points. We provide the first evidence that in trained subjects coingestion of large amounts of Caff (8 mg/kg BM) with CHO has an additive effect on rates of postexercise muscle glycogen accumulation compared with consumption of CHO alone.
Source : J Appl Physiol 2008 vol.105 (1), pp 7 - 13
The effect of topical caffeine on the morphology of swine hypodermis as measured by ultrasound
Peng, T.
Cellulite or lipodystrophy involves the modification of the subcutaneous adipose tissue. A wide variety of topical products is available to combat cellulite, but these have difficulties in being absorbed through the skin. One option is the therapeutic use of the ultrasound to enhance the transdermic transport of these drugs. AIM: The objective of this study was the analysis of the effect of caffeine on the morphology of the swine hypodermis, both when applied topically and in combination with ultrasound treatment. METHODS: The following treatments were applied to the dorsal areas of five pigs (Landrace x Large White, 35 days old, weighing 15 kg each): gel, gel + ultrasound, gel + caffeine (5%, w/w), and gel + caffeine + ultrasound, daily for 15 days. A fifth area received no topical application and was used as a control. Continuous ultrasound of 3 MHz with an intensity of 0.2 W/cm(2) was applied at a rate of 1 min/cm(2). After histological processing (hematoxylin and eosin), morphometric analyses were conducted to determine the thickness and numerical profile of the hypodermis. A one-way analysis variance using a Kolmogorov-Smirnov test was conducted, with a Tukey test used to identify significant differences. A confidence level of P < or = 0.05 was adopted. RESULTS: Caffeine treatment was effective only when associated with ultrasound therapy; the combination resulted in a significant reduction in the thickness of the subcutaneous adipose tissue, as well as damage to the adipocytes, consequently decreasing the number of cells.
CONCLUSION: Ultrasound treatment was effective in increasing the cutaneous permeation of caffeine, as evidenced by the reduction in thickness of the hypodermis and number of adipocytes.
Source : J Cosmet Dermatol 2008 vo/.7 (3), pp 232 - 237
Parental smoking, maternal alcohol, coffee and tea consumption during pregnancy and childhood malignant central nervous system tumours: the ESCALE study (SFCE)
Plichart, M.; Menegaux, F.; Lacour, B.; Hartmann, O.; Frappaz, D.; Doz, F.; Bertozzi, A. I.; Defaschelles, A.
S.; Pierre-Kahn, A.; Icher, C.; Chastagner, P.; Plantaz, D.; Rialland, X.; Hemon, D.; Clavel, J.
Parental smoking and maternal alcohol and caffeinated beverage consumption are prevalent exposures which may play a role, either directly or through their influence on metabolism, in the aetiology of childhood malignant central nervous system (CNS) tumours. The hypothesis was investigated in the Epidemiological Study on childhood Cancer and Leukemia ESCALE study, a national population-based case-control study carried out in France in 2003-2004. The study included 209 incident cases of CNS tumours and 1681 population-based controls, frequency matched with the cases by age and sex. The data were collected through a standardized telephone interview of the biological mothers. No association between maternal smoking during pregnancy and CNS tumours [odds ratio (OR): 1.1 (0.8-1.6)] was observed. Paternal smoking during the year before birth was associated with CNS tumours (P for trend=0.04), particularly astrocytomas [OR: 3.1 (1.3-7.6)]. Maternal alcohol consumption during pregnancy was not associated with CNS tumours. Associations between ependymomas and the highest consumption of coffee [OR: 2.7 (0.9-8.1)] and tea [OR: 2.5 (1.1-5.9)] were observed. A strong association between CNS tumours and the highest maternal consumption of both coffee and tea during pregnancy was observed [OR: 4.4 (1.5-13)]. The results constitute additional evidence for a role of paternal smoking and suggest that maternal coffee and tea consumption during pregnancy may also increase the risk of CNS tumours. The study does not suggest an increased risk of CNS tumours related to alcohol consumption during pregnancy.
Source : Eur J Cancer Prev 2008 vol.17 (4), pp 376 - 383
Protein kinase C inhibitor Go6976 augments caffeine-induced reversal of chemoresistance to cis-diamminedichloroplatinum-II (CDDP) in a human ovarian cancer model
Qamar, L.; Davis, R.; Anwar, A.; Behbakht, K.
Novel strategies for the treatment of chemoresistant ovarian cancer are needed. Caffeine and related compounds have been shown to over-ride G2/M arrest in ovarian cancer cells, increasing toxicity to chemotherapy. Newer compounds have been developed which may have the same effect as and exhibit synergism with caffeine, allowing the use of lower doses. METHODS: We investigated the effects of caffeine and Go6976 in the presence of CDDP in the SKOV3 and A2780 cell lines using proliferation, cell-cycle analysis, apoptosis, and AKT expression. RESULTS: Proliferation of cancer cells was decreased in a dose-dependent manner with caffeine and CDDP, but doses of caffeine required for significant inhibition were higher than that achievable in patients. Go6976, a global PKC inhibitor with G2/M over-ride capability similar to caffeine, when combined with caffeine and CDDP at doses below that required for cell-cycle over-ride produced the growth inhibitory effects of a ten-fold higher caffeine concentration in both cell lines. CDDP induced G2/M arrest was significantly abrogated by caffeine but not by Go6976 alone and no additional effect was seen on G2/M over-ride by the addition of Go6976 to caffeine. Addition of Go6976 to caffeine and CDDP did increase apoptosis but without altering phospho-AKT.
CONCLUSIONS: Go6976, when added to caffeine at doses below that required for cell-cycle over¬ride, augments caffeine in overcoming CDDP resistance in this experimental system. G2/M over-ride is not the mechanism underlying the inhibition of proliferation. An AKT-independent apoptotic mechanism may be responsible.
Source : Gynecol Oncol 2008 vol.110 (3), pp 425 - 431
The relationship between caffeine and blood pressure in preadolescent African American girls
Reddy, J. G.; Ebbert, J. O.; Klesges, L. M.; Enders, F. T.; Klesges, R. C.; Lanctot, J. Q.; McClanahan, B. S.
While high caffeine consumption has been shown to be associated with increased blood pressure in controlled experiments, the relationship between caffeine consumption and blood pressure in preadolescent (ages 6-11 years) and adolescent (ages 12-19 years) children has not been well studied. The primary objective of this study was to assess the cross-sectional relationship between caffeine intake and blood pressure in 8- to 10-year-old African American girls who eat an unrestricted diet. METHODS: Demographic, 24-hour dietary recall, and blood pressure data collected at baseline from 303 African American girls aged 8-10 years in the Girls health Enrichment Multisite Studies (GEMS) cohort were analyzed by using linear and multiple regression models. RESULTS: Dietary caffeine intake was not associated with either systolic or diastolic blood pressure (P=.33 and P=.36, respectively). However, consistent with the literature, height and body mass index were each positively and independently associated with systolic blood pressure (both P<.0001). Height and amount of sodium intake were positively associated with diastolic blood pressure (P=.01 and P=.02, respectively).
CONCLUSIONS: Dietary caffeine intake in low amounts is not associated with elevated blood pressure in 8- to 10-year-old African American girls who eat an unrestricted diet.
Source : Ethn Dis 2008 vol.18 (3), pp 283 - 288 (not available on line)
Caffeine: sleep and daytime sleepiness
Roehrs, T.; Roth, T.
Caffeine is one of the most widely consumed psychoactive substances and it has profound effects on sleep and wake function. Laboratory studies have documented its sleep-disruptive effects. It clearly enhances alertness and performance in studies with explicit sleep deprivation, restriction, or circadian sleep schedule reversals. But, under conditions of habitual sleep the evidence indicates that caffeine, rather then enhancing performance, is merely restoring performance degraded by sleepiness. The sleepiness and degraded function may be due to basal sleep insufficiency, circadian sleep schedule reversals, rebound sleepiness, and/or a withdrawal syndrome after the acute, over-night, caffeine discontinuation typical of most studies. Studies have shown that caffeine dependence develops at relatively low daily doses and after short periods of regular daily use. Large sample and population-based studies indicate that regular daily dietary caffeine intake is associated with disturbed sleep and associated daytime sleepiness. Further, children and adolescents, while reporting lower daily, weight-corrected caffeine intake, similarly experience sleep disturbance and daytime sleepiness associated with their caffeine use. The risks to sleep and alertness of regular caffeine use are greatly underestimated by both the general population and physicians.
Source : Sleep Med Rev 2008 vol. 12 (2), pp 153 - 162
Protective versus promotional effects of white tea and caffeine on PhIP-induced tumorigenesis and beta-catenin expression in the rat
Rong, Wang; Dashwood, W. M.; Loehr, C. V.; Fischer, K. A.; Pereira, C. B.; Louderback, M.; Nakagama, H.; Bailey, G. S.; Williams, D. E.; Dashwood, R. H.
1 year carcinogenicity bioassay was conducted in rats treated with three short cycles of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)/high-fat (HF) diet, followed by 2% white tea (wt/vol), 0.05% epigallocatechin-3-gallate (EGCG) or 0.065% caffeine as sole source of fluid intake. Thirty-two percent of the PhIP/HF controls survived to 1 year, compared with 50, 48.7 and 18.2% in groups given white tea, EGCG and caffeine, respectively. After 1 year, PhIP/HF controls had tumors in the colon, skin, small intestine, Zymbal's gland, salivary gland and pancreas. For all sites combined, excluding the colon, tumor incidence data were as follows: PhlP/HF 69.5%, PhlP/HF + EGCG 48.7%, PhlP/HF + white tea 46.9% and PhlP/HF + caffeine 13.3%. Unexpectedly, a higher incidence of colon tumors was detected in rats post-treated with white tea (69%) and caffeine (73%) compared with the 42% incidence in PhlP/HF
controls. In the colon tumors, beta-catenin mutations were detected at a higher frequency after caffeine posttreatment, and there was a shift toward more tumors harboring substitutions of Gly34 with correspondingly high protein and messenger RNA expression seen for both beta-catenin and c-Myc. c-Myc expression exhibited concordance with tumor promotion, and there was a concomitant increase in cell proliferation versus apoptosis in colonic crypts. A prior report described suppression of PhIP-induced colonic aberrant crypts by the same test agents, but did not incorporate a HF diet. These findings are discussed in the context of epidemiological data which do not support an adverse effect of tea and coffee on colon tumor outcome - indeed, some such studies suggest a protective role for caffeinated beverages.
Source : Carcinogenesis 2008 vol.29 (4), pp 834 - 839
Time-dependent component-specific regulation of gastric acid secretion-related proteins by roasted coffee constituents
Rubach, M.; Lang, R.; Hofmann, T.; Somoza, V.
Consumption of coffee beverages has been reported to cause gastric irritation in some consumers as a result of increased gastric acid secretion. In the complex mechanisms of gastric acid secretion, the activity and expression of the H+,K+-ATPase is regulated by transmitters, such as histamine, acetylcholine, gastrin, somatostatin, and their corresponding receptors. Here, we report the effect of three coffee constituents, chlorogenic acid, caffeine, and N-methyl pyridinium ions, on the expression of the histamine receptor H2, the acetylcholine receptor M3, the gastrin receptor, the somatostatin receptor, and the H+,K+-ATPase. Human gastric cancer cells were exposed to chlorogenic acid, caffeine, or N-methyl pyridinium in their coffee brew-representative concentrations as well as to physiological stimulators of gastric acid secretion. Gene expression levels of receptor proteins and those of the H+,K+-ATPase were measured at different time points by real-time PCR. Expression of prosecretory receptors significantly increased between one and one-half to twofold after treatment with chlorogenic acid or caffeine compared to control cells at the same time point. Chlorogenic acid and caffeine also increased the H+,K+-ATPase gene expression twofold higher compared to control cells. In contrast, N-methyl pyridinium downregulated the expression of the prosecretory gastrin receptor significantly, by -27%. In conclusion, chlorogenic acid, caffeine, and N-methyl pyridinium impair the expression of gastric acid secretion-related proteins in a time-dependent manner. Future work will be aimed at the elucidation of the cooperative interplay of individual components using recombinates of single coffee constituents.
Source : Ann N.Y Acad Sci 2008 vo/.1126, pp 310 - 314
Modulation of cellular response to anticancer treatment by caffeine: inhibition of cell cycle checkpoints, DNA repair and more
Sabisz, M.; Skladanowski, A.
Caffeine and other methylxanthines produce multiple physiologic effects throughout the human body, many of these effects could potentially modulate the activity of anticancer therapy. Caffeine may directly interfere with drug transport to tumor cells by formation of mixed stacking complexes with polyaromatic drugs. If formed in cells, these complexes may also prevent of intercalating drugs from DNA binding and, in this way, lower their antitumor activity. Since many of potent carcinogens are polyaromatic compounds, formation of stacking complexes with carcinogens could be associated with anti-genotoxic activity of caffeine and its use in cancer chemoprevention. Caffeine has also been reported to inhibit ATM and ATR kinases which leads to the disruption of multiple DNA damage-responsive cell cycle checkpoints and greatly sensitizes tumor cells to antitumor agents which induce genotoxic stress. Caffeine may inhibit repair of DNA lesions through a direct interference with DNA-PK activity and other repair enzymes. A number of in vitro and in vivo studies demonstrated that caffeine modulates both innate and adaptive immune responses via inhibition of cyclic adenosine monophosphate (cAMP)-phosphodiesterase. Finally, another group of effects induced by caffeine is mediated through its inhibitory action on adenosine receptors. This may modulate the stability of HIF1 alpha as well as VEGF and interleukin-8 expression in tumor cells, which could have a direct impact on neovascularization of human tumors. In this review, we present different molecular mechanisms by which caffeine and other methylxanthines may directly or indirectly modulate the effect of antitumor treatment in tumor cells and in cancer patients.
Source : Curr Pharm Biotechnol 2008 vo/.9 (4), pp 325 - 336
Caffeine and a selective adenosine A(2B) receptor antagonist but not imidazoline receptor antagonists modulate antinociception induced by diphenyl diselenide in mice
Savegnago, L.; Jesse, C. R.; Nogueira, C. W.
The present study examined the antinociceptive effect of diphenyl diselenide (PhSe)2, given orally (p.o.), in the hot-plate test in mice. The administration of diphenyl diselenide (10-100 mg/kg, p.o.) caused a significant inhibition of thermal nociception induced by hot-plate test in mice. Pretreatment of animals by intraperitoneal route (i.p.) with caffeine (10 mg/kg; a non-specific adenosine receptor antagonist) and PSB1115 (1 mg/kg; an adenosine A(2B) receptor antagonist), but not DPCPX (2 mg/kg; an adenosine A(1) receptor antagonist) and SCH5826 (3 mg/kg; an adenosine A(2A) receptor antagonist) significantly blockaded the antinociceptive effect caused by diphenyl diselenide (10 mg/kg, p.o.) in the hot-plate test. Moreover, the pretreatment of animals with efaroxan (1 mg/kg, i.p.; a mixed I(1) imidazoline/alpha(2)-adrenoceptor antagonist) and idazoxan (3 mg/kg, i.p.; a mixed I(2) imidazoline/alpha(2)-adrenoceptor antagonist) did not significantly reverse the antinociception caused by oral administration of diphenyl diselenide (10 mg/kg, p.o.) in the hot-plate test. These results indicate that diphenyl diselenide produced antinociception in a thermal model of pain in mice and its effect was prevented by caffeine and by a selective adenosine A(2B) receptor, but not by imidazoline receptor antagonists in mice.
Source : Neurosci Lett 2008 vol.436 (2), pp 120 - 123
Caffeine reverses antinociception by amitriptyline in wild type mice but not in those lacking adenosine A1 receptors
Sawynok, J.; Reid, A. R.; Fredholm, B. B.
Amitriptyline is used to treat neuropathic pain in humans. It produces antinociception in several animal models of pain, and this effect is blocked by methylxanthine adenosine receptor antagonists which implicates adenosine it its actions. Here, the antinociceptive effect of amitriptyline, and the ability of caffeine to reverse it, were examined using the formalin test (a model of persistent pain) in wild type mice and mice lacking the adenosine A(1) receptor (A1R). Amitriptyline produced dose-related suppression of flinching in wild type mice following both systemic and intraplantar drug administration; both of these effects were unaltered in A1R -/- mice. Following systemic administration, caffeine reversed the systemic effect of amitriptyline in wild type, but not A1R -/- mice; -/+ mice exhibited an intermediate effect. Intraplantar administration of caffeine also reversed the effect of intraplantar amitriptyline in A1R +/+, but not in -/- or +/- mice. These results indicate that adenosine A(1) receptors are not required in order for amitriptyline to cause antinociception in mice, but they are required to see caffeine reversal of this antinociceptive effect. When A1Rs are present, actions of amitriptyline may, however, partly depend on A1Rs.
Source : Neurosci Lett 2008 vol.440 (2), pp 181 - 184
Caffeine poisoning and lactate rise: an overlooked toxic effect?
Schmidt, A.; Karlson-Stiber, C.
Severe caffeine poisoning is rare but associated with a high mortality. The symptoms are mainly attributable to hyperadrenergic stimulation, are relatively well known and described in the literature. Transient rises in plasma lactate levels may occur but are, however, less well described. We present a case of serious caffeine poisoning with a concomitant rise in lactate treated with a non-selective beta-blocker and discuss briefly the symptomatology, the management of caffeine poisoning and the association between lactate and metabolic acidosis.
Source : Acta Anaesthesiol.Scand 2008 vol.52 (7), pp 1012 - 101
Nicotine and caffeine-mediated modulation in the expression of toxicant responsive genes and vesicular monoamine transporter-2 in 1-methyl 4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson\'s disease phenotype in mouse
Singh, S.; Singh, K.; Patel, S.; Patel, D. K.; Singh, C.; Nath, C.; Singh, M. P.
Epidemiological evidence revealed that cigarette smokers and coffee drinkers have lower risk of Parkinson's disease (PD). Nicotine inhibits monoamine oxidase activity, and induces expression of neurotrophic factors and nicotinic acetylcholinergic receptors. However, caffeine is capable of antagonizing adenosine A(2A) receptor. Toxicant responsive enzymes and vesicular monoamine transporter-2 (VMAT-2) play critical roles in chemically induced PD. Despite some known functions, the effects of nicotine and caffeine on the expression and activity of toxicant responsive genes and on VMAT-2 are still not known. The study was therefore undertaken to investigate the effect of nicotine and caffeine on the expression and activity of toxicant responsive genes, i.e., CYP1A1, CYP2E1, GST-ya, GST-yc, GSTA4-4 and VMAT-2 in the striatum of control and MPTP-induced PD phenotype in mouse. The animals were treated intraperitoneally daily with nicotine (1 mg/kg) or caffeine (20 mg/kg) for 8 weeks, followed by 1-methyl 4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 20 mg/kg)+nicotine or caffeine for 4 weeks. MPTP significantly attenuated CYP1A1 and VMAT-2, and augmented CYP2E1, GST-ya, GST-yc and GSTA4-4 expression/activity. Nicotine or caffeine-treated animals showed significant restoration against most of the MPTP-induced alterations. The results obtained thus suggest that nicotine and caffeine modulate MPTP-induced alterations in CYP1A1, CYP2E1, GST-ya, GST-yc, GSTA4-4 and VMAT-2 expression/activity.
Source : Brain Res 2008 vol. 1207, pp 193 - 206
Caffeine use in sports: considerations for the athlete
Sokmen, B.; Armstrong, L. E.; Kraemer, W. J.; Casa, D. J.; Dias, J. C.; Judelson, D. A.; Maresh, C. M.
The ergogenic effects of caffeine on athletic performance have been shown in many studies, and its broad range of metabolic, hormonal, and physiologic effects has been recorded, as this review of the literature shows. However, few caffeine studies have been published to include cognitive and physiologic considerations for the athlete. The following practical recommendations consider the global effects of caffeine on the body: Lower doses can be as effective as higher doses during exercise performance without any negative coincidence; after a period of cessation, restarting caffeine intake at a low amount before performance can provide the same ergogenic effects as acute intake; caffeine can be taken gradually at low doses to avoid tolerance during the course of 3 or 4 days, just before intense training to sustain exercise intensity; and caffeine can improve cognitive aspects of performance, such as concentration, when an athlete has not slept well. Athletes and coaches also must consider how a person's body size, age, gender, previous use, level of tolerance, and the dose itself all influence the ergogenic effects of caffeine on sports performance.
Source : J Strength Cond Res 2008 vol.22 (3), pp 978 - 986 (not available on line)
Effects of different doses of caffeine on exercise responses in young children
Turley, K. R.; Bland, J. R.; Evans, W. J.
This study investigated the effects of three different doses of caffeine on physiological responses to exercise in young children. METHODS: Forty healthy children (20 boys and 20 girls) volunteered for a random, double-blind, counterbalanced study where they received either placebo (PL), 1 mg.kg(-1) (CAF-1), 3 mg.kg(-1) (CAF-3), or 5 mg.kg(-1) (CAF-5) caffeine, 60 min prior to preexercise measures, followed by cycle ergometer exercise at 25 W and then 60% VO2peak. During this time, heart rate (HR), oxygen consumption (VO2), and respiratory exchange ratio (RER) were measured continuously, while blood pressure (BP) was measured every 2 min. RESULTS: There were no significant gender x treatment interactions, and so the boys' and girls' data were combined. At preexercise, CAF-5 SBP and DBP were significantly (P < 0.05) higher than PL. Both CAF-1 and CAF-3 DBP were also significantly (P < 0.05) higher versus PL at preexercise. There were no treatment effects for exercise BP. At rest and during both exercise intensities, HR was significantly (P < 0.05) lower in CAF-3 (approximately 5 bpm) and CAF-5 (approximately 6 bpm) versus PL. There were no significant effects of CAF on metabolism (VO2 or RER) except for a lower RER in CAF-1 versus CAF-5 at 60% VO2peak.
CONCLUSION: Low, mild, and moderate (1, 3, and 5 mg.kg(-1)) doses of caffeine have no effect on substrate use as reflected by RER. Further, caffeine intake resulted in an increase in BP and decrease in HR at preexercise and a slight decrease in HR with CAF-3 and CAF-5 versus PL during exercise.
Source : Med Sci Sports Exer 2008 vol. 40 (5), pp 871 - 878
Coffee consumption and circulating B-vitamins in healthy middle-aged men and women
Ulvik, A.; Vollset, S. E.; Hoff, G.; Ueland, P. M.
Coffee consumption has been associated with several risk factors for coronary heart disease, including increased cholesterol, increased blood pressure, and increased plasma total homocysteine (tHcy). tHcy is determined by several B-vitamins. However, reports about the association between coffee intake and B-vitamin status are few. METHODS: We measured plasma B-vitamins and tHcy in a cohort of 10,601 healthy, middle-aged Norwegian men and women. Information about lifestyle factors, including coffee consumption, smoking, alcohol use, height, and weight, was obtained by interview. RESULTS: Coffee consumption was dose-dependently associated with reduced plasma B-vitamin concentrations. Compared with coffee abstainers, individuals drinking >or=4 cups/day had 11.7% (P < 0.001), 14.1% (P < 0.001), and 5.5% (P = 0.01) lower plasma concentrations of folate, pyridoxal phosphate, and riboflavin, respectively, and the mean tHcy concentration was 6.8% (P < 0.001) higher. Quantile regression analysis showed essentially no difference in B-vitamin concentrations between coffee consumption categories at low vitamin concentrations but a progressive increase in the difference at higher concentrations. This pattern of differences (effect profile) was found independently of smoking status, alcohol intake, and sex. The decrease in folate explained approximately half of the increase in tHcy.
CONCLUSIONS: Coffee consumption was associated with reduced circulating B-vitamin concentrations. The observed effect profiles indicated that coffee consumption preferentially affected the upper, but not the lower, part of the B-vitamin concentration distributions. We hypothesize that coffee consumption may increase the loss of surplus B-vitamins by excretion in urine.
Source : Clin Chem 2008 vol.54 (9), pp 1489 - 1496
UV-B-Induced Damage to the Lens In Vitro: Prevention by Caffeine
Varma, S. D.; Hegde, K. R.; Kovtun, S.
Ultraviolet (UV) irradiation is one of the significant risk factors in the genesis of cataracts. Pathogenetically, the process can be triggered by the intraocular generation of various reactive species of oxygen that are well known to be initiated by the penetration of light, especially of the UV frequencies. The contribution of UV exposure in the etiology of this disease is likely to increase further due to ozone depletion in the upper atmosphere. The present studies were undertaken to examine if the UV effects can be attenuated with the xanthine-based alkaloids primarily present in tea and coffee. We have examined this possibility by in vitro lens culture studies with caffeine. As expected, mice lenses incubated in Tyrode solution exposed to UV at 302 nm are physiologically damaged, as evidenced by the inhibition of the active transport of (86)Rb(+), an ion acting as a surrogate of the K(+). There was a simultaneous decrease in the levels of adenosine triphosphate and glutathione. The addition of caffeine to the medium prevented such deleterious effects. That caffeine and perhaps other xanthinoids have a protective effect against cataract formation induced by UV has hence been demonstrated for the first time.
Source : J Ocul Pharmacol Ther 2008 vo/.24 (5), pp 439 - 444
The effect of caffeine ingestion on human neutrophil oxidative burst responses following time-trial cycling Source
Walker, G. J.; Dziubak, A.; Houghton, L.; Prendergast, C.; Lim, L.; Bishop, N. C.
Following fixed-duration exercise of submaximal intensity, caffeine ingestion is associated with an attenuation of the exercise-induced decline in N-formyl-methionyl-phenyl-alanine (f-MLP) stimulated neutrophil oxidative burst. However, the response following high-intensity exhaustive exercise is unknown. Nine endurance-trained male cyclists ingested 6 mg caffeine or placebo per kilogram of body mass 60 min before cycling for 90 min at 70% of maximal oxygen consumption (VO2max) and then performing a time-trial requiring an energy expenditure equivalent to 30 min cycling at 70% maximum power output. Time-trial performance was 4% faster in the caffeine than in the placebo trial (P = 0.043). Caffeine was associated with an increased plasma adrenaline concentration after 90 min of exercise (P = 0.046) and immediately after the time-trial (P = 0.02). Caffeine was also associated with an increased serum caffeine concentration (P < 0.01) after 90 min of exercise and immediately after the time-trial, as well as 1 h after the time-trial. However, the f-MLP-stimulated neutrophil oxidative burst response fell after exercise in both trials (P = 0.002). There was no effect of caffeine on circulating leukocyte or neutrophil counts, but the lymphocyte count was significantly lower on caffeine (20%) after the time-trial (P = 0.003). Our results suggest that high-intensity exhaustive exercise negates the attenuation of the exercise-induced decrease in neutrophil oxidative burst responses previously observed when caffeine is ingested before exercise of fixed duration and intensity. This may be associated with the greater increase in adrenaline concentration observed in the present study.
Source : J Sports Sci 2008 vol.26 (6). pp 611 - 619
The effect of caffeine as an ergogenic aid in anaerobic exercise
Woolf, K.; Bidwell, W. K.; Carlson, A. G.
This study examined the ergogenic effect of caffeine (5 mg/kg body wt.) vs. placebo during anaerobic exercise. 18 male athletes (24.1 ± 5.8 yr; BMI 26.4 ± 2.2 kg/m2) completed a leg press, chest press and Wingate test. During the caffeine trial, more total wt. was lifted with the chest press, and a greater peak power was obtained during the Wingate test. No differences were observed between treatments for the leg press and average power, min. power, and power drop (Wingate test). There was a significant treatment main effect found for postexercise glucose and insulin concn.; higher concn. were found in the caffeine trial. A significant interaction effect (treatment and time) was found for cortisol and glucose concn.; both increased with caffeine and decreased with placebo. Postexercise systolic blood pressure was significantly higher during the caffeine trial. No differences were found between treatments for serum free-fatty-acid concn., plasma lactate concn., serum cortisol concn., heart rate and rating of perceived exertion. Thus, it is concluded that a moderate dose of caffeine results in more total wt. lifted for the chest press and a greater peak power attained during the Wingate test in competitive athletes.
Source : Intern J Sport Nutr Exerc Metab 2008 vol.18 (4), pp 412 - 429
The coffee diterpene kahweol induces heme oxygenase-1 via the PI3K and p38/Nrf2 pathway to protect human dopaminergic neurons from 6-hydroxydopamine-derived oxidative stress
Yong, Pil Hwang; Hye, Gwang Jeong
Mechanisms by which the coffee diterpene kahweol provides protection to neuronal cells against cell death induced by the Parkinson's disease-related neurotoxin 6-hydroxydopamine (6-OHDA) were investigated. Pretreatment of SH-SY5Y neuroblastoma cells with kahweol significantly reduced 6-OHDA-induced generation of reactive oxygen species (ROS), caspase-3 activation and subsequent cell death. Kahweol also up-regulated heme oxygenase-1 (HO-1) expression, which conferred neuroprotection against 6-OHDA-induced oxidative injury. Moreover, kahweol induced PI3K and p38 activation, which are involved in the induction of Nrf2, HO-1 expression and neuroprotection. These results suggest that regulation of the antioxidant enzyme HO-1 via the PI3K and p38/Nrf2 signalling pathways controls intracellular levels of ROS.
Source : FEBS Letters 2008 vol.582 (17), pp 2655 - 2662
Caffeine reduces TNFalpha up-regulation in human adipose tissue primary culture
Dray, C.; Daviaud, D.; Guigne, C.; Valet, P.; Castan-Laurell, I.
Adipose tissue secretions play an important role in the development of obesity-related pathologies such as diabetes. Through inflammatory cytokines production, adipose tissue stromavascular fraction cells (SVF), and essentially macrophages, promote adipocyte insulin resistance by a paracrine way. Since xanthine family compounds such as caffeine were shown to decrease inflammatory production by human blood cells, we investigated the possible effect of caffeine on Tumor Necrosis Factor alpha (TNFalpha) and Interleukin-6 (IL-6) expression by human adipose tissue primary culture. For that purpose, human subcutaneous adipose tissue obtained from healthy non-obese women (BMI: 26.7 +/- 2.2 kg/m2) after abdominal dermolipectomy, was split into explants and cultured for 6 hours with or without caffeine. Three different concentrations of caffeine were tested (0.5 microg/mL, 5 microg/mL and 50 microg/mL). After 6 hours of treatment, explants were subjected to collagenase digestion in order to isolate adipocytes and SVF cells. Then, TNFalpha and IL-6 mRNA were analysed by real-time PCR alternatively in adipocytes and SVF cells. In parallel, we checked gene expression of markers involved in adipocyte differenciation and in SVF cells inflammation and proliferation. Our findings show a strong and dose dependent down-regulation of TNF-alpha gene expression in both adipocyte and SVF cells whereas IL-6 was only down regulated in SVF cells. No effect of caffeine was noticed on the other genes studied. Thus, caffeine, by decreasing TNFalpha expression, could improve adipose tissue inflammation during obesity.
Source : J Physiol Biochem 2008 vo/.63 (4), pp 329 - 336