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At least 973 records · Page 54Linked to original sources
PubMed1977

Gas chromatographic determination of residual methylene chloride and trichloroethylene in decaffeinated instant and ground coffee with electrolytic conductivity and electron capture detection.

A method is described for the quantitative determination of residual methylene chloride (MC) and trichloroethylene (TCE) in decaffeinated instant and ground roasted coffees. The residual solvents were isolated by a closed system vacuum distillation technique with toluene as a carrier solvent, chromatographed on Chromosorb 102, detected by both electron capture and electrolytic conductivity detectors, and quantitated by comparison with an internal standard. Average recoveries of MC from instant and ground coffees spiked at 1, 10, and 25 ppm were 100.0 (88-113), 93.2 (92-95), and 97.7% (94-102%); and for TCE, 97.2 (92-101), 96.2 (95-99), and 96.5% (92-100%), respectively. The results from both detectors are compared. At lower attenuations, levels less than 1 ppm can be readily measured. The procedure developed was applied to domestic and imported coffee samples.

Chromatography, Gas↗
PubMedDate not supplied

Further study on the effects of coffee cherry on spontaneous mammary tumourigenesis in mice: effects of methanol extract.

To examine the effective components in the antitumourigenic role of water extract of coffee cherry (CC), and the residue after removal of beans, the dry matter of coffee cherry was extracted repeatedly by 60% methanol and further divided into water-soluble and -insoluble fractions (CC-W and CC-M, respectively). Free access to CC-W (0.25% in tap water) markedly inhibited mammary tumour development in SHN virgin mice, while it had no effect on the growth of normal and preneoplastic mammary glands and established tumours. Associated with this, urinary excretion of some components and intrathymic T cell differentiation were stimulated by the treatment with the CC. CC-W had little affect on the endocrine system, including serum prolactin level, oestrous cycles and endocrine organs, but retarded ovarian degeneration in mice developing mammary tumours. The finding in CC-W were generally similar to those in CC. Fat emulsion of CC-M, which was only checked for mammary tumour growth owing to the limited amount available, showed no effect at the dose level used (0.25% in drinking water). Finally, the previous and the present findings taken together strongly suggest that the effective components of coffee cherry are in the water-soluble fraction.

Analysis of Variance↗
PubMed1998

Isolation of a Paracoccidioides brasiliensis strain from the soil of a coffee plantation in Ibiá, State of Minas Gerais, Brazil.

Paracoccidioides brasiliensis has rarely been isolated from its habitat in rural areas. In order to investigate the hypothesis that human infection with this fungus is linked to coffee plantations (Coffea arabica), material was collected monthly over a period of 1 year from farms in the town of Ibiá, State of Minas Gerais, Brazil. A total of 760 samples of soil, coffee leaves and fruits was cultured and inoculated into mice. A fungus isolated from the liver of a mouse inoculated with soil showed temperature-dependent dimorphism and in vitro mycelium and yeast phases characteristic of P. brasiliensis. Yeast cells of this fungus caused disseminated infection after intraperitoneal inoculation in Wistar rats from which the fungus was re-isolated. An antigen reacting with sera from patients with paracoccidioidomycosis was obtained from this P. brasiliensis strain; antigenic identity with strain 339 and with four other P. brasiliensis strains was detected by gel immunodiffusion. However, when the exo-antigen was submitted to SDS-PAGE, we observed low gp43 expression in this new strain, which we called Ibiá. The isolation of P. brasiliensis from the soil at a coffee plantation suggests that this is one of its habitats and supports the hypothesis of acquisition of paracoccidioidomycosis during agricultural activity in these areas.

Agricultural Workers' Diseases↗
PubMed1976

High-pressure liquid chromatography of caffeine in coffee.

A new method is described for the determination of caffeine in coffee, based on high-pressure liquid chromatography. The caffeine is extracted from the sample with water and/or methylene chloride, and then separated from interfering materials by passing an aliquot of the extract through a high-pressure column containing sulfonated cation exchange resin, using 0.01M nitric acid as the mobile phase. An ultraviolet detector measures the absorption of the solution directly. The method is rapid and eliminates the lengthy separations common to other methods. The procedure was applied successfully to decaffeinated and non-decaffeinated green, roasted, and instant coffees. This method gives a more accurate measure of the caffeine content in decaffeinated coffee samples than the micro Bailey-Andrew and modified Levine methods, with equal or better precision. This method gives results equal to those obtained by the official methods for non-decaffeinated samples.

Caffeine↗
PubMed2001

Sex differences in estimation of time intervals and in reaction time are removed by moderate but not high doses of caffeine in coffee.

Estimation of the passage of time in the seconds-to-minutes range and reaction time are strongly dependent on a hypothetical internal clock. Dopamine is the neurotransmitter most closely related to the rate of this clock. Caffeine, probably the most consumed drug in the world, leads to an augmentation of dopamine neurotransmission. In this study coffee, which reproduces the conditions under which caffeine is normally ingested, containing 3, 75, 150 or 300 mg of caffeine, was given to healthy male and female volunteers. A computerized time estimation and reaction time test was carried out 50 min after ingestion. Sex differences in placebo control subjects (who took decaffeinated coffee with 3 mg of caffeine), with females making more accurate estimates of time intervals than males and males showing shorter reaction times than females, were removed in subject taking doses of 75 and 150 mg of caffeine in the case of time estimation and 150 mg in the case of reaction time. The 300 mg dose induced overestimation of time in females and shortened the reaction time in males. There were no sex differences in the pharmacokinetics of caffeine, as measured in salivary concentration of caffeine using high-performance liquid chromatography. Results indicating sex differences in time estimation or reaction time should not be generalized from the laboratory to real life without considering the fact that everyday coffee consumption may eliminate these differences. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗
PubMedDate not supplied

Determination of the triacylglycerol composition of coffee beans by reverse-phase high-performance liquid chromatography.

Reverse-phase HPLC with refractive index and light scattering detectors in isocratic and gradient elution modes, respectively, was applied for the separation of the major triacylglycerols (TAG) in coffee lipids. Twelve TAG species could be identified and determined using a linear gradient of acetonitrile in dichloromethane: dichloroethane. The quantitative evaluation was based on the relative area percentages derived directly from a data-station. The procedure was applied to determine the TAG composition of three types of coffee beans harvested in two coffee producing areas in Brazil and dried by two commonly used procedures. No significant differences in the TAG compositions due to the type, origin and drying procedure were found.

Brazil↗
PubMed2002

The coffee components kahweol and cafestol induce gamma-glutamylcysteine synthetase, the rate limiting enzyme of chemoprotective glutathione synthesis, in several organs of the rat.

The coffee components kahweol and cafestol (K/C) were reported to be protective against mutagenic damage by heterocylic amines and aflatoxin B1 in the rat, while in humans the consumption of coffee with a high K/C content was associated with a lower rate of colon tumors. An important mechanism of this antimutagenic effect appears to be the potential of K/C to induce glutathione-S-transferase (GST) and to enhance hepatic levels of glutathione (GSH), the co-factor of GST, which is independently involved in further protective mechanisms. In the present study, we investigated mechanisms and organ specificities (liver, kidney, lung, colon) of the K/C effect on GSH levels, and particularly the role of gamma-glutamylcysteine synthetase (GCS), the rate limiting enzyme of GSH synthesis. Chows containing one of four concentrations of either a 1:1 mixture of K/C (0.012-0.122%) or of cafestol alone (0.006-0.061%) were fed to male F344 rats for 10 days. In the K/C-treated livers, a dose-dependent increase of up to 2.4-fold in the activity of GCS was observed, being statistically significant even at the lowest dose, and associated with an increase in GSH of up to three-fold. Notably, the highest dose doubled the hepatic mRNAs of the heavy and light subunits of GCS, suggesting enhanced transcription. In the extrahepatic organs, GCS activity and GSH levels were increased as well, although more moderately than in the liver. Since enhancement of GCS had also been observed as a consequence of oxidative stress, the possibility of such an involvement in the actions of K/C was examined by determining hepatic thiobarbituric acid reactive substances and the ratio of oxidized and reduced GSH. However, no evidence of oxidative stress was detected. In summary, K/C increased GSH levels apparently through the induction of the rate limiting enzyme of GSH synthesis, which may be a key factor in the chemopreventive potential of coffee components.

Aminoacyltransferases↗
PubMed2002

New procedures for determination of acids in coffee extracts, and observations on the development of acidity upon ageing.

Analysis of the acid content of coffee extracts has been performed by adaptation of a procedure, recently introduced by our laboratory, to the task of evaluating both the "volatile" and "non volatile" fractions. Besides useful changes in the preparation of the acid pool, diazobutane was used to obtain esters of volatile acids suitable for GC-MS analysis, to minimize losses of material by evaporation. The new procedures have been used to evaluate changes in the acid content of some Italian-style roasted coffee extracts after accelerated ageing (65 degrees C, 72 h) and in coffee beans after different amounts of roasting. The origin of formation of volatile acidity was also investigated. Electronic supplementary material is available if you access this article at http://dx.doi.org/10.1007/s00216-002-1561-y On that page (frame on the left side) a link takes you directly to the supplementary material.

Journal Article↗
PubMed2005

Fungal epiphytes and endophytes of coffee leaves (Coffea arabica).

Plants harbor diverse communities of fungi and other microorganisms. Fungi are known to occur both on plant surfaces (epiphytes) and inside plant tissues (endophytes), but the two communities have rarely been compared. We compared epiphytic and endophytic fungal communities associated with leaves of coffee (Coffea arabica) in Puerto Rico. We asked whether the dominant fungi are the same in both communities, whether endophyte and epiphyte communities are equally diverse, and whether epiphytes and endophytes exhibit similar patterns of spatial heterogeneity among sites. Leaves of naturalized coffee plants were collected from six sites in Puerto Rico. Epiphytic and endophytic fungi were isolated by placing leaf pieces on potato dextrose agar without and with surface sterilization, respectively. A total of 821 colonies were isolated and grouped into 131 morphospecies. The taxonomic affinities of the four most common nonsporulating fungi were determined by sequencing the nuclear ribosomal internal transcribed spacer (ITS) region: two grouped with Xylaria and one each with Botryosphaeria and Guignardia. Of the most common genera, Pestalotia and Botryosphaeria were significantly more common as epiphytes; Colletotrichum, Xylaria, and Guignardia were significantly more common as endophytes. Suprisingly, more morphospecies occurred as endophytes than as epiphytes. Differences among sites in number of fungi per plant were significant. Thus epiphytic and endophytic communities differed greatly on a single leaf, despite living only millimeters apart, and both communities differed from site to site. Significant correlations between occurrence of fungal morphospecies suggested that fungi may have positive or negative effects on their neighbors. This is the first quantitative comparison of epiphytic and endophytic fungal floras in any plant, and the first to examine endophytic fungi or epiphytic fungi in leaves of coffee, one of the world's most valuable crops.

Classification↗
PubMed2006

An effective and low-cost culture medium for isolation and growth of Xylella fastidiosa from citrus and coffee plants.

Buffered charcoal-yeast extract medium (BCYE) has been used for isolation of Xylella fastidiosa from citrus (Citrus sinensis) and coffee (Coffea arabica) plants affected by citrus variegated chlorosis (CVC) and coffee leaf scorch (CLS). BCYE is composed of ACES (2-[2-amino-2oxoethyl) amino]-ethanesulfonic acid) buffer, activated charcoal, yeast extract, L-cysteine, ferric pyrophosphate, and agar. ACES buffer is costly and not always commercially available in Brazil, and the L-cysteine and ferric pyrophosphate need to be filter sterilized in 0.22-mum pore membranes before inclusion in the medium. Omission of L-cysteine, addition of magnesium sulfate, and replacements of ACES and ferric pyrophosphate for potassium phosphate and ferrous sulfate resulted in an effective, less expensive, and entirely autoclavable medium, named phosphate buffered charcoal-yeast extract medium (PCYE). The final cost of PCYE was approximately one tenth that of BCYE. Its effectiveness was tested for the isolation of X. fastidiosa from symptomatic leaves collected from 52 citrus plants affected by CVC and 43 coffee plants affected by CLS. PCYE was as effective as BCYE and has been used routinely in our and other laboratories for isolation, growth, and quantification of X. fastidiosa from plant tissues.

Brazil↗
PubMed2004

Abscisic acid controls embryo growth potential and endosperm cap weakening during coffee (Coffea arabica cv. Rubi) seed germination.

The mechanism and regulation of coffee seed germination were studied in Coffea arabica L. cv. Rubi. The coffee embryo grew inside the endosperm prior to radicle protrusion and abscisic acid (ABA) inhibited the increase in its pressure potential. There were two steps of endosperm cap weakening. An increase in cellulase activity coincided with the first step and an increase in endo-beta-mannanase (EBM) activity with the second step. ABA inhibited the second step of endosperm cap weakening, presumably by inhibiting the activities of at least two EBM isoforms and/or, indirectly, by inhibiting the pressure force of the radicle. The increase in the activities of EBM and cellulase coincided with the decrease in the force required to puncture the endosperm and with the appearance of porosity in the cell walls as observed by low-temperature scanning electronic microscopy. Tissue printing showed that EBM activity was spatially regulated in the endosperm. Activity was initiated in the endosperm cap whereas later during germination it could also be detected in the remainder of the endosperm. Tissue printing revealed that ABA inhibited most of the EBM activity in the endosperm cap, but not in the remainder of the endosperm. ABA did not inhibit cellulase activity. There was a transient rise in ABA content in the embryo during imbibition, which was likely to be responsible for slow germination, suggesting that endogenous ABA also may control embryo growth potential and the second step of endosperm cap weakening during coffee seed germination.

Abscisic Acid↗
PubMed2004

Application of RNAi to confirm theobromine as the major intermediate for caffeine biosynthesis in coffee plants with potential for construction of decaffeinated varieties.

The caffeine biosynthetic pathway in coffee plants has been proposed to involve three distinct N -methyltransferases, xanthosine methyltransferase (XMT), 7- N -methylxanthine methyltransferase (MXMT; theobromine synthase), and 3,7-dimethylxanthine methyltransferase (DXMT; caffeine synthase). We previously isolated all corresponding cDNAs designated as CaXMT1 , CaMXMT1 , CaMXMT2 and CaDXMT1 , respectively, and showed that caffeine was indeed synthesized in vitro by the combination of their gene products. In order to regulate caffeine biosynthesis in planta , we suppressed expression of CaMXMT1 by the double stranded RNA interference (RNAi) method. For this purpose, we first established a protocol for efficient somatic embryogenesis of Coffea arabica and C. canephora , and then Agrobacterium -mediated transformation techniques. The RNAi transgenic lines of embryogenic tissues derived from C. arabica and transgenic plantlets of C. canephora demonstrated a clear reduction in transcripts for CaMXMT1 in comparison with the control plants. Transcripts for CaXMT1 and CaDXMT1 were also reduced in the most cases. Both embryonic tissues and plantlets exhibited a concomitant reduction of theobromine and caffeine contents to a range between 30% and 50% of that of the control. These results suggest that the CaMXMT1 -RNAi sequence affected expression of not only CaMXMT1 itself, but also CaXMT1 and CaDXMT1 , and that, since the reduction in theobromine content was proportional to that for caffeine, it is involved in the major synthetic pathway in coffee plants. The results also indicate that the method can be practically applied to produce decaffeinated coffee plants.

Caffeine↗
PubMed2005

Caffeine production in tobacco plants by simultaneous expression of three coffee N-methyltrasferases and its potential as a pest repellant.

Caffeine (1,3,7-trimethylxanthine) is derived from xanthosine through three successive transfers of methyl groups and a single ribose removal in coffee plants. The methyl group transfer is catalyzed by N-zmethyltransferases, xanthosine methyltransferase (XMT), 7-methylxanthine methyltransferase (MXMT) and 3,7-dimethylxanthine methyltransferase (DXMT). We previously cloned three genes encoding each of these N-methyltransferases from coffee plants, and reconstituted the final sequence of the caffeine synthetic pathway in vitro. In the present study, we simultaneously expressed these coffee genes in tobacco plants (Nicotiana tabacum), using a multiple-gene transfer method, and confirmed successful caffeine production up to 5 microg g(-1) fresh weight in leaves of the resulting transgenic plants. Their effects on feeding behavior of tobacco cutworms (Spodoptera litura), which damage a wide range of crops, were then examined. Leaf disc choice test showed that caterpillars selectively fed on the wild-type control materials, or positively avoided the transgenic materials. The results suggest a novel approach to confer self-defense by producing caffeine in planta. A second generation of transgenic crops containing caffeine may save labor and agricultural costs and also mitigate the environmental load of pesticides in future.

Animals↗
PubMed2005

It takes the whole brain to make a cup of coffee: the neuropsychology of naturalistic actions involving technical devices.

Left hemisphere dominance has been established for use of single familiar tools and tool/object pairs, but everyday action in natural environment frequently affords multi-step actions with more or less novel technical devices. One purpose of our study was to find out whether left hemisphere dominance extends to such naturalistic action. Another aim was to analyze the cognitive components contributing to success or failure. Patients with LBD and aphasia, patients with RBD, and healthy controls were examined on experimental tests assessing retrieval of functional knowledge from semantic memory, inference of function from structure, and solution of mechanical and non-mechanical multi-step problems, and were confronted with two naturalistic tasks involving technical devices: preparing coffee with a drip coffee maker and fixing a cassette recorder. Both patient groups were about equally impaired on both naturalistic actions. Analysis of the experimental tests and their correlations to naturalistic actions suggested that different cognitive deficits caused failure in both patient groups, and that in LBD patients there were also different causes for failure on both naturalistic actions. The main difficulty of RBD patients seemed to reside in the demand to keep track of multi-step actions. In aphasic LBD patients difficulties with making coffee but not the cassette recorder were correlated with aphasia and defective retrieval of functional knowledge from semantic memory, whereas the cassette recorder correlated more strongly with a test probing solution of multi-step mechanical problems. Inference of function from structure which had been shown to be important for use of single familiar tools or tool/objects pairs [Goldenberg, G., Hagmann, S. (1998). AT Tool use and mechanical problem solving in apraxia. Neuropsychologia, 36, 581-589] appeared to play only a subordinate role for naturalistic actions involving technical devices.

Activities of Daily Living↗
PubMed2003

Isolation of a new dual-functional caffeine synthase gene encoding an enzyme for the conversion of 7-methylxanthine to caffeine from coffee (Coffea arabica L.).

In coffee and tea plants, caffeine is synthesized from xanthosine via a pathway that includes three methylation steps. We report the isolation of a bifunctional coffee caffeine synthase (CCS1) clone from coffee endosperm by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) technique using previously reported sequence information for theobromine synthases (CTSs). The predicted amino acid sequences of CCS1 are more than 80% identical to CTSs and are about 40% similar to those of tea caffeine synthase (TCS1). Interestingly, CCS1 has dual methylation activity like tea TCS1.

Amino Acid Sequence↗
PubMed2003

Inhibition of caffeine biosynthesis in tea (Camellia sinensis) and coffee (Coffea arabica) plants by ribavirin.

The effects of ribavirin, an inhibitor of inosine-5'-monophosphate (IMP) dehydrogenase, on [8-(14)C]inosine metabolism in tea leaves, coffee leaves and coffee fruits were investigated. Incorporation of radioactivity from [8-(14)C]inosine into purine alkaloids, such as theobromine and caffeine, guanine residues of RNA, and CO(2) was reduced by ribavirin, while incorporation into nucleotides, including IMP and adenine residues of RNA, was increased. The results indicate that inhibition of IMP dehydrogenase by ribavirin inhibits both caffeine and guanine nucleotide biosynthesis in caffeine-forming plants. The use of IMP dehydrogenase-deficient plants as a potential source of good quality caffeine-deficient tea and coffee plants is discussed.

Antimetabolites↗
PubMed1998

Non-destructive analysis of natural variability in bean caffeine content of Laurina coffee.

In order to conserve the germination power of coffee beans, only a tiny portion of endosperm was excised for caffeine determination. These non-destructive, single-bean analyses of the low-caffeine coffee mutant Laurina (C. arabica cv. laurina) revealed (a) a variation of the caffeine content from 0.36 to 1.08%, with lowest values found in the tissue culture-derived genotypes (somaclones), (b) a markedly lower mean caffeine content (0.56-0.61% dry wt) in the somaclones than in the parent line (0.68-0.71%), and (c) a high correlation between the caffeine contents of the bean and cotyledons emerged from it. Hence, breeding for low-caffeine coffee will be facilitated in future by simply analysing the cotyledons for this character. The combination of "somaclones" and single-seed analysis may be a useful and general strategy to tailor the phytochemical pattern of plants.Additionally, the young leaflets of Laurina, equally to the seeds furnished with a low caffeine content, were studied with respect to the N-methyltransferase (NMT) activities catalysing the last two steps in caffeine biosynthesis. The related activities were much lower than of the cultivar Catuai indicating that the lr lr alleles of Laurina, responsible for the reduction in half the "normal" caffeine content, interfere with the synthesis and not with the catabolism of caffeine.

Journal Article↗
PubMed1991

Effects of caffeinated coffee on intraocular pressure.

This study examined the effects of caffeinated coffee on the intraocular pressure of nonglaucomatous subjects. Subjects were randomly assigned to receive each of three treatments: caffeinated coffee, hot water, and no fluid. All subjects were given the three treatment conditions over 3 days. The study revealed that intraocular pressure after ingesting caffeinated coffee was significantly higher than after receiving the other two treatment conditions. It was further found that increased intraocular pressure was maintained at significant levels over a 3-hour period. No significant changes were found in the pulse rate, and findings on blood pressure were inconclusive.

Adult↗