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PubMed2003

Coffee diterpenes prevent benzo[a]pyrene genotoxicity in rat and human culture systems.

The coffee-specific diterpenes cafestol and kahweol (C+K) have been identified as two important chemoprotective agents in coffee. In the present study, the potential preventive effects of C+K against the genotoxicity of B[a]P were investigated in rat primary hepatocytes and in human bronchial Beas-2B cells. Several independent mechanisms were identified and their respective contribution to the overall protective effects was determined. A marked dose-dependent inhibition by C+K of B[a]P DNA-binding was found in cells of both origins. However, data showed that the significant induction by C+K of the detoxifying enzyme GST-Yp subunit is the key mechanism of protection against B[a]P DNA-binding in rat liver. In contrast, the phase I-mediated mechanism where C+K produce an inhibition of CYP 1A1 induction by B[a]P is of key significance for the C+K protection in human Beas-2B cells. Moreover, this effect suggests a novel mechanism of chemoprotection by the coffee diterpenes cafestol and kahweol.

Animals↗

PubMed2003

The first committed step reaction of caffeine biosynthesis: 7-methylxanthosine synthase is closely homologous to caffeine synthases in coffee (Coffea arabica L.).

In coffee and tea plants, caffeine is synthesized from xanthosine via a pathway that has three methylation steps. We identified and characterized the gene encoding the enzyme for the first methylation step of caffeine biosynthesis. The full-length cDNA of coffee tentative caffeine synthase 1, CtCS1, previously isolated by the rapid amplification of cDNA ends was translated with an Escherichia coli expression system and the resultant recombinant protein was purified using Ni-NTA column. The protein renamed CmXRS1 has 7-methylxanthine synthase (xanthosine:S-adenosyl-L-methionine methyltransferase) activity. CmXRS1 was specific for xanthosine and xanthosine 5'-monophosphate (XMP) could not be used as a substrate. The K(m) value for xanthosine was 73.7 microM. CmXRS1 is homologous to coffee genes encoding enzymes for the second and third methylation steps of caffeine biosynthesis.

Caffeine↗

PubMed1997

The cholesterol-raising diterpenes from coffee beans increase serum lipid transfer protein activity levels in humans.

Cafestol and kahweol-diterpenes present in unfiltered coffee-strongly raise serum VLDL and LDL cholesterol and slightly reduce HDL cholesterol in humans. The mechanism of action is unknown. We determined whether the coffee diterpenes may affect lipoprotein metabolism via effects on lipid transfer proteins and lecithin:cholesterol acyltransferase in a randomized, double-blind cross-over study with 10 healthy male volunteers. Either cafestol (61-64 mg/day) or a mixture of cafestol (60 mg/day) and kahweol (48-54 mg/day) was given for 28 days. Serum activity levels of cholesterylester transfer protein, phospholipid transfer protein and lecithin:cholesterol acyltransferase were measured using exogenous substrate assays. Relative to baseline values, cafestol raised the mean (+/- S.D.) activity of cholesterylester transfer protein by 18 +/- 12% and of phospholipid transfer protein by 21 +/- 14% (both P < 0.001). Relative to cafestol alone, kahweol had no significant additional effects Lecithin:cholesterol acyltransferase activity was reduced by 11 +/- 12% by cafestol plus kahweol (P = 0.02). It is concluded that the effects of coffee diterpenes on plasma lipoproteins may be connected with changes in serum activity levels of lipid transfer proteins.

Adult↗

PubMed2000

Uptake of radiolabelled ochratoxin A from soil by coffee plants.

[3H, 14C] Ochratoxin A, prepared biosynthetically, was applied in dilute NaHCO3 solution to the soil in which coffee plants had grown to four pairs of leaves. Three weeks later the compound, isolated from dilute NaHCO3 extract of leaves by immunoaffinity chromatography, was detected by scintillation counting as a 1-2 ppm component of leaf dry weight, greatly exceeding the trace (ppb) occurrence of ochratoxin A in some green coffees, which therefore might arise in the field directly from fungal activity in soil rather than from fungal infection of cherries or processed green coffee.

Carbon Radioisotopes↗

PubMed2001

Production of ochratoxin A by Aspergillus carbonarius on coffee cherries.

Robusta coffee cherries collected before and during sun drying from two coffee farms in Thailand were examined for moulds producing ochratoxin A (OA). Aspergillus ochraceus was only detected in one sample, whereas Aspergillus carbonarius was isolated from 7 out of 14 samples. On gamma-irradiated coffee cherries, each of the six tested A. carbonarius strains produced OA. More than 4800 microg kg(-1) of toxin were detected under optimal conditions (25 degrees C, a(w) 0.99). OA production was strongly reduced (230 microg kg(-1)) at an a(w) of 0.94.

Aspergillus↗

PubMed2003

The source of ochratoxin A in Brazilian coffee and its formation in relation to processing methods.

A total of 408 Brazilian coffee samples was examined during the 1999 and 2000 coffee harvest seasons for the presence of ochratoxin A (OA) and fungi with the potential to produce it. Samples came from four regions: Alta Paulista (western area of São Paulo State), Sorocabana (southwest São Paulo State), Alta Mogiana (northeast São Paulo State) and Cerrado Mineiro (western area of Minas Gerais State). Cherries and beans were examined at different stages: immature, mature and overripe cherries from trees, overripe cherries from the ground and beans during drying and storage on the farm. For mycological studies, the cherries and beans were surface disinfected with chlorine, plated on Dichloran 18% Glycerol Agar at 25 degrees C for 5-7 days and analysed for the presence of Aspergillus ochraceus and closely related species, A. carbonarius and A. niger. More than 800 isolates of fungi belonging to these species were identified and studied for the ability to produce OA using the agar plug technique and thin layer chromatography (TLC). A. niger was the species found most commonly (63% of isolates of these three species), but only 3% of them produced OA. A. ochraceus also occurred commonly (31% of isolates), and 75% of those studied were capable of OA production, a much higher percentage than reported elsewhere. A. carbonarius was found (6% of isolates) only in Alta Paulista, the hottest region studied, and only from beans in the drying yard or in storage. However, 77% of the A. carbonarius isolates were capable of producing OA. Average infection rates for cherries taken from trees were very low, but were higher in fruit taken from the ground, from the drying yard and from storage, indicating infection by toxigenic species after harvest. The average OA content in 135 samples of mature cherries from trees, overripe from trees, overripe from the ground, drying yard and storage was 0.1, <0.2, 1.6, 2.1 and 3.3 microg/kg, respectively. Although individual OA levels varied widely, only 9 of the 135 samples analysed exceeded 5 microg/kg OA, with one sample of poor quality dried coffee in excess of 100 microg/kg OA. The causes of high contamination were investigated on the farms concerned and several critical points were found, relating both to local climatic conditions and the drying processes used.

Aspergillus↗

PubMed1998

Modulation of metal-induced genotoxicity by Maillard reaction products isolated from coffee.

PM2 bacteriophage DNA was exposed to non-dialysable Maillard reaction products (MRPs) isolated from brewed (Br), boiled (Bo) and instant (I) coffee brew extracts in a Fe2+ catalysed Fenton reaction at four pH conditions (i.e. 7.5, 4.0, 3.2, 2.6). MRPs were incubated with DNA either directly with Fe2+, or following a short preincubation period conducted with Fe2+ in an atmosphere of oxygen or argon. Damage to supercoiled DNA resulting in strand scissions as characterized by both nicked circular and linear forms were found to occur either with coffee MRPs or Fe2+ alone, in a dose-dependent manner at all pH conditions tested. At low MRP concentrations, damage to DNA with respect to Fe2+ was lowered only when MRPs were preincubated with Fe2+ in argon or oxygen before incubating with DNA. The addition of MRPs and Fe2+ to DNA without preincubation, had no effects in protecting DNA damage. This finding showed that a preincubation step is necessary for MRPs to chelate Fe2+ in order to mitigate the Fenton reaction. In contrast, the protective effects against Fe2+-induced DNA breakage by MRPs were lost at high coffee MRP concentrations, irrespective of the incubation method used. Increasingly higher concentrations of MRPs in combination with Fe2+ actually enhanced the breakage of DNA with respect to the control. These results indicate that MRPs at high concentrations do not improve Fe2+ ion chelation, but rather accelerate the DNA breakage by possibly changing the redox state of the transition element.

Chromatography, Gel↗

PubMed2002

Identification of N1-methyl-2-pyridone-5-carboxamide and N1-methyl-4-pyridone-5-carboxamide as components in urine extracts of individuals consuming coffee.

Caffeine metabolites were extracted from urine samples collected 4 h after consumption of a cup of coffee and were separated by high-performance liquid chromatography (HPLC) on a C18 (5 microm) reverse-phase column using an acetonitrile (5%), acetic acid (0.05%) solution as the mobile phase. The elution profiles indicated the constant presence of a major and a minor components eluting between the caffeine metabolites 5-acetamido-6-formyl-3-methyluracil (AFMU) and 7-methylxanthine (7X) in an approximate nine. A procedure was developed for the isolation of the major component in an apparent pure form, and the yield was 10-20 mg from 400 ml of urine. The minor component was isolated in an apparent pure form by this procedure as well, and the yield was 0.5 mg from 200 ml of urine. The average ratio of the two components in urine, UV absorption and 1H-NMR spectra of the two components, and 13C-NMR spectrum, mass spectrum and elemental analysis of the major component identified the major and minor components as N(1)-methyl-2-pyridone-5-carboxamide and N(1)-methyl-4-pyridone-5-carboxamide, respectively, two major metabolites of the vitamin niacin present in a significant amount in coffee beans. The two metabolites were present in the same average amount in urine extracts of individuals irregardless of coffee consumption. The findings are briefly discussed in relation to the nutritional sources of niacin and to current procedures for measuring amounts of the two metabolites in urine samples.

Chromatography, High Pressure Liquid↗

PubMed1998

Isolation of an antibacterial component from roasted coffee.

A coffee beverage obtained from instant dark coffee that had been previously shown to possess high antibacterial activity, was acidified (pH 2) and extracted with ethyl acetate. After alkalinization (pH 12) the aqueous phase was re-extracted with the organic solvent. The acidic and basic extracts were evaporated to dryness and the aqueous phase freeze-dried. Residues were dissolved in sterile water and assayed for antibacterial activity against two reference bacteria (Staphylococcus aureus ATCC 25923 and Streptococcus mutans 9102). The acidic extract was found to be highly active and was separated by gel permeation chromatography (GPC) into five fractions. Fractions GPC4 and GPC5 were found to possess antibacterial activity: most of the activity was evident in fraction GPC5. These fractions were separated by RP-HPLC using a gradient elution with methanol water as mobile phase. Both GPC fractions gave an active subfraction with methanol-water (70:30, v/v). The experimental conditions used to separate the antibacterial compound that originates during the roasting process, indicate that it possesses low molecular mass (probably no more than 200 Da), weak acidic properties and an lambda(max) at 205 nm. The very small amount of this compound isolated from roasted coffee, indicates that it may be a very strong antibacterial agent.

Anti-Bacterial Agents↗

PubMed1996

The consumption of tobacco, alcohol, and coffee in Caucasian male twins: a multivariate genetic analysis.

Despite the fact that epidemiologic studies demonstrate a consistent covariation between the use of tobacco, alcohol, and coffee, most previous behavioral genetic-studies have determined the contribution of genetic and environmental influences as if the consumption of these substances occurred independently of each other. In this study, we used multivariate structural equation modeling to determine the genetic and environmental overlap in the observed correlations between tobacco smoking and alcohol and coffee drinking in 173 monozygotic and 183 dizygotic male twin pairs (M age = 59 years; range = 52-66 years) who participated in a follow-up cardiovascular examination of the National Heart, Lung, and Blood Institute's Twin Study. Consistent with hypothesized psychoneurogenetic predispositions for the joint use of these substances, the most parsimonious model fitting these data identified a common genetic latent factor underlying the observed associations between smoking, alcohol, and coffee use in this cohort. This factor, herein called polysubstance use, underscores the role of genetic influence on the clustering of these behaviors in the same individual.

Aged↗

PubMed2003

Coffee intake and mortality from liver cirrhosis.

PURPOSE: The aim of the study was to evaluate the association between coffee consumption and mortality from liver cirrhosis. METHODS: We conducted a mortality follow-up of 51,306 adults who underwent screening for cardiovascular disease from 1977 to 1983. During the subsequent 17 years, the total number of deaths from all causes in the studied cohort was 4207. Fifty-three had the diagnosis of cirrhosis mentioned on the death certificate; of these, 36 had alcoholic cirrhosis. RESULTS: The relative risk of liver cirrhosis mentioned on the death certificate associated with an increase of two cups of coffee, adjusted for sex, age, alcohol use and other major cardiovascular risk factors was 0.6 (95% confidence interval, 0.5-0.8). For alcoholic cirrhosis the results were identical. When studying cirrhosis as the underlying cause of death, the inverse relationship becomes somewhat stronger. CONCLUSIONS: The present study confirms the existence of an inverse association between coffee consumption and liver cirrhosis.

Adult↗

PubMed1998

Identification of hydroxyhydroquinone in coffee as a generator of reactive oxygen species that break DNA single strands.

A component in instant coffee that caused DNA single strand breaks was isolated by successive ethyl acetate:ethanol extraction, silica gel column chromatography and high performance liquid chromatography using a reversed phase column. The active component was identified as hydroxyhydroquinone (HHQ). Incubation of supercoiled pBR 322 DNA with HHQ at 0.1 mM in phosphate buffer (pH 7.4) at 37 degreesC for 1 h caused single strand breaks, and reactive oxygen species, hydrogen peroxide and hydroxyl radical, were involved in DNA breaking by HHQ. Genotoxic effects of HHQ including DNA breaking activity through generation of reactive oxygen species have been well-demonstrated because the component is considered to be an important genotoxic intermediate metabolite of benzene. Occurrence of HHQ in coffee must have an important significance to consider genotoxicity of coffee.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Packed bed column fermenter and kinetic modeling for upgrading the nutritional quality of coffee husk in solid-state fermentation.

Studies were carried out to evaluate solid-state fermentation (SSF) for the upgradation of the nutritional quality of coffee husk by degrading the caffeine and tannins present in it. SSF was carried out by Aspergillus niger LPBx in a glass column fermenter using factorial design experiments and surface response methodology to optimize bioprocess parameters such as the substrate pH and moisture content and aeration rate. The first factorial design showed that the moisture content of the substrate and aeration rate were significant factors for the degradation of toxic compounds, which was confirmed by the second factorial design too. The kinetic study showed that the degradation of toxic compounds was related to the development of the mold and its respiration and also to the consumption of the reducing sugars present in coffee husk. From the values obtained experimentally for the oxygen uptake rate and CO(2) evolved, the system determined a biomass yield (Y(x/o)) of 3.811 (g of biomass).(g of consumed O(2))(-1) and a maintenance coefficient (m) of 0.0031 (g of consumed O(2)).(g biomass of biomass)(-1).h(-1). The best results on the degradation of caffeine (90%) and tannins (57%) were achieved when SSF was carried out with a 30 mL.min(-1) aeration rate using coffee husk having a 55% initial moisture content. The inoculation rate did not affect the metabolization of the toxic compounds by the fungal culture. After SSF, the protein content of the husk was increased to 10.6%, which was more than double that of the unfermented husk (5.2%).

Algorithms↗

PubMed2002

Chemical characterization of galactomannans and arabinogalactans from two arabica coffee infusions as affected by the degree of roast.

Galactomannans and arabinogalactans compose almost exclusively the polysaccharide fraction of roasted coffee infusions. To increase the knowledge about the effect of the degree of roast (DR) in the amount and chemical structure of the galactomannans and arabinogalactans, two arabica coffees of different geographical origins (Costa Rica and Brazil) were roasted for three degrees of roast (DRs 4.7-5.0, 8.7, and 10% of dry weight loss of green coffee beans, on a dry basis). The high molecular weight material was extracted with hot water and dialyzed (molecular weight cutoff >12 kDa), and the material was separated in three cold-water-soluble fractions by graded addition of ethanol. The degree of polymerization and the degree of branching of the galactomannans decreased with the increase of the DR. As the DR increased, less branched arabinogalactans were extracted. The relative amount of terminally linked arabinosyl residues of the arabinogalactans decreased with the increase in DR, and the terminally linked galactosyl residues increased. Also, the size of the arabinosyl side chains of the arabinogalactans decreased with the increase in DR.

Chemical Fractionation↗

PubMed2002

Application of (1)h NMR and multivariate statistics for screening complex mixtures: quality control and authenticity of instant coffee.

Principal components analysis (PCA) followed by linear discriminant analysis (LDA) of the nuclear magnetic resonance (NMR) spectra from 98 instant spray-dried coffees, obtained from 3 different producers, correctly attributed 99% of the samples to their manufacturer. Blind testing of the PCA model with a further 36 samples of instant coffee resulted in a 100% success rate in identifying the samples from the 3 manufacturers. Coffees from one manufacturer were also assigned into 2 groups using these techniques, and the compound 5-(hydroxymethyl)-2-furaldehyde was identified as the primary marker of differentiation.

Analysis of Variance↗

PubMed2002

Effect of roasting on the antioxidant activity of coffee brews.

Colombian Arabica coffee beans were roasted to give light, medium, and dark samples. Their aqueous extracts were analyzed by gel filtration chromatography, UV-visible spectrophotometry, capillary electrophoresis, and the ABTS(*)(+) assay. A progressive decrease in antioxidant activity (associated mainly with chlorogenic acids in the green beans) with degree of roasting was observed with the simultaneous generation of high (HMM) and low molecular mass (LMM) compounds possessing antioxidant activity. Maximum antioxidant activity was observed for the medium-roasted coffee; the dark coffee had a lower antioxidant activity despite the increase in color. Analysis of the gel filtration chromatography fractions showed that the LMM fraction made a greater contribution to total antioxidant activity than the HMM components.

Antioxidants↗

PubMed2003

The elusiveness of coffee aroma: new insights from a non-empirical approach.

Aroma is central to a pleasurable eating/drinking experience but is one of the most labile components of food. Coffee is an outstanding example. Attempts to avoid or control aroma degradation are often frustrated by ignorance of the microscopic mechanisms that are responsible for it. One of the processes most frequently invoked is radical formation, yet the identity of the radicals and their involvement in aroma degradation are poorly understood at the molecular level. Here a step forward in the fundamental understanding of this complex problem is taken by identifying the most relevant radicals and their products using first-principles calculations. Over 100 radicals originating from key aroma compounds found in coffee and other foods have been studied and classified according to an unambiguous criterion: their thermodynamic stability relative to common radical sources. This classification scheme predicts that most aroma molecules are resistant to both peroxidation and attack from phenolic antioxidants but are unstable with respect to radicals such as .OH. Dimers--generated from radical reactions--were also considered, and the most volatile species, which may further contribute to coffee aroma degradation, were focused on. Those--which are very few indeed--that have this potential have been identified.

Coffee↗

PubMed2005

Unraveling the contribution of melanoidins to the antioxidant activity of coffee brews.

Instant coffees produced from the same green coffee beans were supplied from a company in different roasting degrees, light, medium, and dark. Melanoidins were obtained by ultrafiltration (10 kDa) and subsequent diafiltration. Pure melanoidins were isolated from melanoidins after overnight incubation in 2 M NaCl. The antioxidant activities of instant coffees, melanoidins, and pure melanoidins were tested using the conjugated diene formation from a 2,2'-azobis(2-amidinopropane) dihydrochloride-induced linoleic acid oxidation in an aqueous system. No significant differences were found between melanoidins and pure melanoidins with different roasting degrees. Therefore, the contribution of the pure melanoidin fraction to the total antioxidant activity of melanoidins was significantly lower. More than 50% of the antioxidant activity of melanoidins is due to low molecular weight compounds linked non-covalently to the melanoidin skeleton. A new concept of the overall antioxidant properties of food melanoidins is described, where chelating ability toward low molecular weight antioxidant compounds is connected to the stabilization of these compounds involved in the shelf life of the product.

Amidines↗