The inhibitory effects of coffee on radical-mediated oxidation and mutagenicity

Protective role of a melon superoxide dismutase combined with gliadin (GliSODin) on the status of lipid peroxidation and antioxidant defense against azoxymethane-induced experimental colon carcinogenesis

Background

Azoxymethane (AOM) is a potent carcinogenic agent commonly used to induce colon cancer in rats and mice, with the cytotoxicity of AOM mediated by oxidative stress.

Aim of Study

This study investigated the protective effect of a natural antioxidant (GliSODin) against AOM-induced oxidative stress and carcinogenesis in rat colon.

Methods

Twenty male Wistar rats were randomly divided into four groups (five rats/group). The control group was fed a basal diet. AOM-treated group (AOM) was fed a basal diet and received intraperitoneal injections of AOM for 2 weeks at a dose of 15 mg/kg. The GliSODin treatment group (superoxide dismutase [SOD]) received oral supplementation of GliSODin (300 mg/kg) for 3 months, and the fourth combined group received AOM and GliSODin (AOM + SOD). All animals were continuously fed ad libitum until the age of 16 weeks when all rats were sacrificed. The colon tissues were examined microscopically for pathological changes and aberrant crypt foci (ACF) development, oxidant status (lipid peroxidation-LPO), and enzyme antioxidant system (glutathione [GSH], GSH-S-transferase, catalase, and SOD).

Results

Our results showed that AOM induced ACF development and oxidative stress (GSH depletion and lipid peroxidation) in rat colonic cells. The concomitant treatment of AOM with GliSODin significantly ameliorated the cytotoxic effects of AOM.

Conclusion

The results of this study provide in vivo evidence that GliSODin reduced the AOM-induced colon cancer in rats, through their potent antioxidant activities.

Herbicide biomonitoring in agricultural workers in Valle del Mayo, Sonora Mexico

Valle del Mayo is an important agricultural area at the northwest of Mexico where up to 20,000 L of a mix composed of glyphosate and tordon is used in drains and canals. This study was carried out in order to evaluate the cellular damage caused by glyphosate, aminomethylphosphonic acid (AMPA), and picloram in agricultural workers. Biomonitoring was performed through the quantification of herbicides in urine using HPLC (high-performance liquid chromatography) to then evaluate the cellular damage in exposed people by means of an evaluation of micronuclei and cellular proliferation in lymphocyte cultures. The urine samples (n = 30) have shown a concentration of up to 10.25 μg/L of picloram and 2.23 μg/L of AMPA; no positive samples for glyphosate were reported. The calculation of the external dose reveals that agricultural workers ingest up to 146 mg/kg/day; however, this concentration does not surpass the limits that are allowed internationally. As for the results for the micronuclei test, 53% of the workers showed cellular damage, and the nuclear division index test reported that there was a significant difference (P < 0.05) between the exposed and the control population, which indicated that the exposure time to pesticides in the people of Valle del Mayo can induce alterations which can cause chronic damage.

Quantitation of Methionine Sulfoxide in Milk and Milk-Based Beverages-Minimizing Artificial Oxidation by Anaerobic Enzymatic Hydrolysis

Protein oxidation in milk products may entail flavor changes through reactions at methionine residues. However, little is known about the extent of methionine oxidation in milk and milk products. In the present study, a method for quantitation of methionine, methionine sulfoxide, and methionine sulfone by a stable isotope dilution assay using HILIC-ESI-MS/MS was established. For the quantitation of protein-bound analytes, anaerobic enzymatic hydrolysis was optimized to suppress artificial methionine oxidation. Moreover, the method allowed for monitoring of artificial oxidation by coincubation of the labeled probe [²H₈]methionine. The percentage of oxidized methionine was low in UHT milk (up to 1.6%) and evaporated milk (up to 8.8%), but higher in beverages such as cocoa milk drinks (up to 19.0%) and coffee milk drinks (up to 32.8%), resulting in methionine sulfoxide concentrations of up to 6.7 g/kg protein in the latter. These products are important dietary sources of methionine sulfoxide. Model studies revealed that methionine residues can be oxidized strongly in the presence of phenolic compounds such as catechin, caffeic acid, and gallic acid, which are present in cocoa and coffee and may account for the high extent of oxidation in commercial samples.

The Chemistry of Protein Oxidation in Food

Oxidation is one of the deterioration reactions of proteins in food, the importance of which is comparable to others such as Maillard, lipation, or protein-phenol reactions. While research on protein oxidation has led to a precise understanding of the processes and consequences in physiological systems, knowledge about the specific effects of protein oxidation in food or the role of "oxidized" dietary protein for the human body is comparatively scarce. Food protein oxidation can occur during the whole processing axis, from primary production to intestinal digestion. The present review summarizes the current knowledge and mechanisms of food protein oxidation from a chemical, technological, and nutritional-physiological viewpoint and gives a comprehensive classification of the individual reactions. Different analytical approaches are compared, and the relationship between oxidation of food proteins and oxidative stress in vivo is critically evaluated.

Anti-inflammatory and antioxidant properties of jervine, a sterodial alkaloid from rhizomes of Veratrum album

BACKGROUND

Veratrum, hellebore is an important plant species of the Liliaceae family and jervine is the characteristic steroidal alkaloid constituent of Veratrum album.

PURPOSE

In the current study, anti-inflammatory and antioxidant effects of jervine isolated from NH₄OH-benzene extract of V. album rhizomes were investigated on CAR induced paw edema in rats.

METHODS/STUDY DESIGN

In inflammatory study, 50, 100, 200 and 400  mg/kg doses of jervine, 25  mg/kg doses of DIC and IND were orally administered, and the volume of the foots were measured up to their knee arthrosis by plethismometer. After one hour of the oral administration of the all treatments, 0.1 ml of CAR solution (1%) was injected into the foot of the all rat groups and the volume of the foots were measured during 5 h after CAR injection. GPx, SOD, GR, MPO, CAT enzymes activities and GSH, LPO levels of the supernatants of paw homogenates and inflammation biomarkers such as TNF-α and IL-1β in the rats serums were also estimated.

RESULTS

According to the present results, jervine exerted 50.4-73.5% anti-inflammatory effects in carrageenan induced paw edema. Inflammation biomarkers such as TNF-α, IL-1β and MPO that increased by CAR injection were suppressed by the administrations of all doses of jervine, IND and DIC. In all paw tissues, LPO levels as indicator of oxidative tissue damage were found to be high in CAR-treated group and it was found to be decreased in all doses of jervine.

CONCLUSION

Jervine, DIC and IND reduced the negative effects of CAR due to increasing effects on the SOD, CAT, GSH, GPx and GR antioxidants.

Acidity and Antioxidant Activity of Cold Brew Coffee

The acidity and antioxidant activity of cold brew coffee were investigated using light roast coffees from Brazil, two regions of Ethiopia, Columbia, Myanmar, and Mexico. The concentrations of three caffeoylquinic acid (CQA) isomers were also determined. Cold brew coffee chemistry was compared to that of hot brew coffee prepared with the same grind-to-coffee ratio. The pH values of the cold and hot brew samples were found to be comparable, ranging from 4.85 to 5.13. The hot brew coffees were found to have higher concentrations of total titratable acids, as well as higher antioxidant activity, than that of their cold brew counterparts. It was also noted that both the concentration of total titratable acids and antioxidant activity correlated poorly with total CQA concentration in hot brew coffee. This work suggests that the hot brew method tends to extract more non-deprotonated acids than the cold brew method. These acids may be responsible for the higher antioxidant activities observed in the hot brew coffee samples.

Nutritional recommendations for individuals with Flammer syndrome

The Flammer syndrome (FS) describes the phenotype of people with a predisposition for an altered reaction of the blood vessels to stimuli like coldness or emotional stress. The question whether such people should be treated is often discussed. On the one hand, most of these subjects are healthy; on the other hand, FS seems to predispose to certain eye diseases such as normal tension glaucoma or retinitis pigmentosa or systemic diseases such as multiple sclerosis or tinnitus. A compromise between doing nothing and a drug treatment is the adaption of nutrition. But what do we mean by healthy food consumption for subjects with FS? The adaption of nutrition depends on the health condition. Whereas patients with e.g. a metabolic syndrome should reduce their calorie intake, this can be counterproductive for subjects with FS, as most subjects with FS have already a low body mass index (BMI) and the lower the BMI the stronger the FS symptoms. Accordingly, while fasting is healthy e.g. for subjects with metabolic syndrome, fasting can even dangerously aggravate the vascular dysregulation, as it has been nicely demonstrated by the loss of retinal vascular regulation during fasting. To give another example, while reducing salt intake is recommended for subjects with systemic hypertensions, such a salt restriction can aggravate systemic hypotension and thereby indirectly also the vascular regulation in subjects with FS. This clearly demonstrates that such a preventive adaption of nutrition needs to be personalized.

Impacts of discarded coffee waste on human and environmental health

Coffee is one of the most widely consumed beverages throughout the world. So far, many studies have shown the properties of coffee beverages, but little is known about its impacts on human and environmental health from its discard in the environment. So, the present work aims to investigate the mutagenic, genotoxic, cytotoxic and ecotoxic effects of leached (LE) and solubilized (SE) extracts from coffee waste, simulating the disposal of this residue in landfills and via sewage systems, respectively. Chemical analyses were also carried out. LE and SE induced mutagenicity in the TA98 Salmonella strain with and without exogenous metabolization (S9). In the TA100 only SE induced mutagenicity, what was observed without S9. An increase in the frequency of micronuclei was observed in HepG2 cell line after 3 and 24h of exposure to both extracts. No cytotoxic effects were observed in HepG2 cells by WST-1 assay. The EC50 values for the LE and SE were 1.5% and 11.26% for Daphnia similis, 0.12% and 1.39% for Ceriodaphnia dubia and 6.0% and 5.5% for Vibrio fischeri, respectively. Caffeine and several transition metals were found in both extracts. Coffee waste discarded in the environment may pose a risk to human and environmental health, since this compound can cause DNA damage and present toxicity to aquatic organisms.

Coffee Consumption Is Positively Associated with Longer Leukocyte Telomere Length in the Nurses' Health Study

BACKGROUND

Coffee is an important source of antioxidants, and consumption of this beverage is associated with many health conditions and a lower mortality risk. However, no study, to our knowledge, has examined whether varying coffee or caffeine consumption levels are associated with telomere length, a biomarker of aging whose shortening can be accelerated by oxidative stress.

OBJECTIVE

We performed a large comprehensive study on how coffee consumption is associated with telomere length.

METHODS

We used data from the Nurses' Health Study (NHS), a prospective cohort study of female nurses that began in 1976. We examined the cross-sectional association between coffee consumption and telomere length in 4780 women from the NHS. Coffee consumption information was obtained from validated food-frequency questionnaires, and relative telomere length was measured in peripheral blood leukocytes by the quantitative real-time polymerase chain reaction. Unconditional logistic regression was used to obtain ORs when the telomere length outcome was dichotomized at the median. Linear regression was used for tests of trend with coffee consumption and telomere length as continuous variables.

RESULTS

Higher total coffee consumption was significantly associated with longer telomeres after potential confounding adjustment. Compared with non-coffee drinkers, multivariable ORs for those drinking 2 to <3 and ≥3 cups of coffee/d were, respectively, 1.29 (95% CI: 0.99, 1.68) and 1.36 (95% CI: 1.04, 1.78) (P-trend = 0.02). We found a significant linear association between caffeine consumption from all dietary sources and telomere length (P-trend = 0.02) after adjusting for potential confounders, but not after additionally adjusting for total coffee consumption (P-trend = 0.37).

CONCLUSIONS

We found that higher coffee consumption is associated with longer telomeres among female nurses. Future studies are needed to better understand the influence of coffee consumption on telomeres, which may uncover new knowledge of how coffee consumption affects health and longevity.

Comparison of antioxidant activity between green and roasted coffee beans using molecular methods

Coffee is one of the most popular and widely consumed beverages worldwide due to its pleasant taste and aroma. A number of studies have been performed to elucidate the possible beneficial effects of coffee consumption on human health and have shown that coffee exhibits potent antioxidant activity, which may be attributed mainly to its polyphenolic content. However, there is also evidence to suggest that coffee roasting (the procedure which turns green coffee beans to the dark, roasted ones from which the beverage derives) may alter the polyphenolic profile of the beans (e.g., via the Maillard reaction) and, concomitantly, their antioxidant activity. In the present study, the antioxidant activity of 13 coffee varieties was examined in both green and roasted coffee bean extracts using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-eth-ylbenzothiazoline-6-sulfonic acid) (ABTS^•+) radical scavenging assays. In addition, 5 selected varieties were also examined for their protective effects against peroxyl and hydroxyl radical-induced DNA strand cleavage. Finally, C2C12 murine myoblasts were treated with non-cytotoxic concentrations of the most potent extract in order to examine its effects on the cellular redox status by measuring the glutathione (GSH) and reactive oxygen species (ROS) levels by flow cytometry. Our results revealed that, in 8 out of the 13 coffee varieties, roasting increased free radical scavenging activity as shown by DPPH and ABTS^•+ assays. Moreover, we found that when one coffee variety was roasted for different amounts of time, the increase in the antioxidant activity depended on the roasting time. By contrast, in 5 varieties, roasting reduced the antioxidant activity. Similar differences between the roasted and green beans were also observed in the free radical-induced DNA strand cleavage assay. The observed differences in the antioxidant activity between the different coffee varieties may be attributed to their varying polyphenolic content and composition, as well as to the different molecules produced during roasting. In addition, in the cell culture assay, the tested coffee extract led to increased GSH levels in a dose-dependent manner, indicating the enhancement of cellular antioxidant mechanisms.

Antioxidant and Antiradical Activity of Coffee

This review summarizes published information concerning the determination of antioxidant activity (AA) in coffee samples by various methods (ORAC, FRAP, TRAP, TEAC, etc.) in vitro and limited data of antiradical activity of coffee products in vitro and in vivo. Comparison is carried out of the AA of coffee Arabica and coffee Robusta roasted at different temperatures as well as by different roasting methods (microwave, convection, etc.). Data on the antiradical activity of coffee is provided. The antioxidant activity of coffee, tea, cocoa, and red wine is compared. At the end of this review, the total antioxidant content (TAC) of coffee samples from 21 coffee-producing countries as measured by an amperometric method is provided. The TAC of green and roasted coffee beans is also compared.

Analysis of in vitro chemoprevention of genotoxic damage by phytochemicals, as single agents or as combinations

Cancer chemoprevention with low-dose combinations of bioactive phytochemicals instead of single agents has been suggested to induce less toxicity and improve efficacy. In this study, we selected four plant food-based phytochemicals, viz. chlorogenic acid (CLA), pelargonidin (PEL), resveratrol (RES) and epigallocatechin gallate (EGCG) to evaluate the in vitro chemoprevention of genotoxic damage in HL-60 cells. These agents were tested either individually or as a combination at two concentrations (with a 10-fold difference) against the genotoxins mitomycin C (MMC), diepoxybutane (DEB) and patulin (PAT). Our preliminary ferric reducing antioxidant power (FRAP) assay demonstrated additive effects when PEL, CLA, RES and EGCG were combined. Results of the cytokinesis-block micronucleus test showed significant protection against genotoxic damage induced by PAT, DEB and MMC when CLA, PEL, RES and EGCG were tested individually. This protective effect of the phytochemicals was not concentration-related. Both low- and high-concentration combinations of CLA, PEL, RES and EGCG showed significant reducing effects on the frequencies of micronuclei induced by PAT, DEB and MMC. However, the micronucleus test did not provide indications of additive or synergistic effects with this combination of phytochemicals. In conclusion, the chemo-preventive effects of PEL, CLA, RES and EGCG against genotoxic damage induced by MMC, DEB and PAT are indicative of a 'saturation effect' when higher concentrations and combinations of these phytochemicals are used.

Effects of the consumption of caffeinated and decaffeinated instant coffee beverages on oxidative stress induced by strenuous exercise in rats

Many authors attribute the antioxidant activity of brewed coffee to its caffeine content. In addition, caffeine intake has been associated with increased performance during physical exercise. This study analyzed the in vivo effects of drinking caffeinated and decaffeinated instant coffee (8%, w/v) on oxidative stress and antioxidant enzyme activity in the anterior tibialis muscles of rats subjected to intense exercise. It was observed that exercise induced lipid peroxidation (estimated using malondialdehyde) and protein oxidation (evaluated by determining the formation of carbonyl groups) in the muscle (P < 0.05). Decaffeinated instant coffee and caffeine solution did not exhibit antioxidant activity in vivo. Caffeinated instant coffee beverage intake did not induce changes in superoxide dismutase and glutathione peroxidase activities but was able to diminish lipid and protein oxidation in the anterior tibialis muscles of rats after exercise (P < 0.05), contributing to a reduction in the oxidative stress triggered by exercise.

Coffee consumption and mortality due to all causes, cardiovascular disease, and cancer in Japanese women

Coffee contains various compounds that have recently been reported to exert beneficial health effects. However, the conclusion of its relation with mortality has not yet been reached. In this study, we aimed to investigate the associations between coffee consumption and all-cause and cause-specific mortality in Japan. We included 37,742 participants (18,287 men and 19,455 women) aged 40-64 y without a history of cancer, myocardial infarction, or stroke at baseline in our analysis, based on the Miyagi Cohort Study initiated in 1990. The outcomes were mortality due to all causes, cardiovascular disease (CVD), and cancer. During the 10.3 y of follow-up, 2454 participants died, including 426 due to CVD and 724 due to cancer. In women, the multivariate hazard ratios (HR) (95% CI) for all-cause mortality in participants who drank coffee never, occasionally, 1-2 cups (150-300 mL)/d, and > or =3 cups/d were 1.00, 0.88 (0.73-1.06), 0.82 (0.66-1.02), and 0.75 (0.53-1.05), respectively (P-trend = 0.04). For CVD mortality in women, the multivariate HR (95% CI) were 1.00, 0.56 (0.36-0.86), 0.48 (0.29-0.80), and 0.45 (0.20-1.03), respectively (P-trend = 0.006). Of the specific CVD diseases, there was a strong inverse association between coffee consumption and mortality due to coronary heart disease (CHD) in women (P-trend = 0.02) but not in men. Death due to cancer was not associated with coffee consumption in either men or women, except for colorectal cancer in women. Our results suggest that coffee may have favorable effects on morality due to all causes and to CVD, especially CHD, in women.

Long-term ingestion of reduced glutathione suppressed an accelerating effect of beef tallow diet on colon carcinogenesis in rats

PURPOSE

We have shown previously that long-term feeding of beef tallow increases colorectal cancer in rats. This study investigated the effects of enzymic antioxidant, reduced glutathione (GSH), on colon carcinogenesis in rats fed with beef tallow.

METHODS

Colon carcinogenesis was induced by intraperitoneal injection of azoxymethane (AOM) to rats. Rats were fed with 10% beef tallow supplemented with or without 1% GSH in drinking water. Aberrant crypt foci (ACF) and expression of beta-catenin in colonic mucosa were examined at 12 weeks. Cancers, related substances of oxidative stress and arachidonic acid cascade in plasma and normal colonic mucosa were determined at 44 weeks.

RESULTS

GSH attenuated the number of ACF increased by beef tallow, but GSH had no influence on expression of beta-catenin increased by AOM. Incidence of colon cancer was no different with or without GSH, but GSH attenuated the number of colon cancers in each rat. GSH suppressed plasma malondialdehyde concentration. GSH increased GSH concentration and activities of catalase, glutathione peroxidase and superoxide dismutase in colonic mucosa, and decreased cyclooxygenase-2, prostaglandin E2 and thromboxane B2 levels.

CONCLUSIONS

This study indicated that GSH suppressed the number of ACF, but the attenuation of colon carcinogenesis was limited to the number of colon cancers, although anti-oxidative effects and suppressive effects of arachidonic acid cascade were demonstrated by several indexes. These results suggested that colon carcinogenesis enhanced by beef tallow was partly caused by oxidative stress and arachidonic acid cascade, which were reduced by GSH.

Protective role of luteolin on the status of lipid peroxidation and antioxidant defense against azoxymethane-induced experimental colon carcinogenesis

The modifying effect of dietary exposure to a flavonoid, luteolin (LUT) during the azoxymethane (AOM)-induced colon carcinogenesis was investigated in this study. Aberrant crypt foci (ACF), lipid peroxidation (LPO), enzymic and non-enzymic antioxidants and histopathological analysis were performed. Colon carcinogenesis was induced by injecting 15 mg/body kg weight of AOM, intraperitoneally (i.p.), once in a week for 3 weeks in male Balb/c mice. AOM-induced mice were treated with LUT (1.2mg of LUT/kg body weight/day orally). After the experimental period, frequency of ACF, levels of thiobarbutaric acid reactive substances (TBARS) and hydroxy radical (OH ) were found to be increased, whereas glutathione (GSH), Vitamins C, E and A were decreased in the plasma and colon of AOM-induced mice. However, LUT treatment to AOM-induced mice significantly decreased the incidence of ACF, levels of TBARS and OH with a concordant increase in non-enzymic antioxidants in plasma and colon tissue. The activities of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were found to be decreased due to the induction of colon cancer in mouse. LUT treatment ameliorated the activities of these antioxidant enzymes. The histological study revealed a significant increase in the enlarged nuclei and hyperchromatism of cells in AOM-induced mice whereas LUT significantly reduced the signs in the colon. The immunohistochemical expression of MDA-DNA adduct was studied. In AOM-induced group, the expression was increased and treatment with LUT decreased significantly. The present study depicts that LUT can act as an effective chemopreventive agent against colon cancer.

Coffee consumption protects human lymphocytes against oxidative and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2) induced DNA-damage: Results of an experimental study with human volunteers

Aim of the study was to investigate the impact of coffee on DNA-stability in humans. DNA-damage was monitored in lymphocytes of eight individuals with single cell gel electrophoresis assays before and after consumption of 600 ml coffee (400 ml paper filtered and 200 ml metal filtered/d) for five days. Under standard conditions, no alteration of DNA-migration was seen, but a strong reduction of DNA-migration attributable to endogenous formation of oxidised purines and pyrimidines was detected with restriction enzymes; furthermore DNA-damage caused by reactive oxygen radicals (H2O2 treatment) and by the heterocyclic aromatic amine 3-amino-1-methyl-5H-pyrido[4,3-b]indole-acetate was significantly reduced after coffee consumption by 17% and 35%, respectively. Also in in vitro experiments, inhibition of H2O2 induced DNA-damage was observed with coffee at low concentrations (<or= 25 microl/ml) whereas the diterpenoids cafestol and kahweol caused only marginal effects indicating that the effects of coffee are due to scavenging effects of other constituents. Enzyme measurements showed that additionally induction of antioxidant enzymes may play a role: while the activity of glutathione peroxidase was only marginally increased after coffee consumption, a significant (38%) increase of superoxide dismutase activity was detected. Comparisons with results of earlier studies suggest that coffee consumption may prevent oxidative DNA-damage to a higher extent as diets enriched in fruits and vegetables.

Protective effects of kahweol and cafestol against hydrogen peroxide-induced oxidative stress and DNA damage

There is an increasing evidence that oxidative stress is implicated in the processes of inflammation and carcinogenesis. It has been shown that kahweol and cafestol, coffee-specific diterpenes, exhibit chemoprotective effects. This study investigated the effects of kahweol and cafestol, coffee-specific diterpenes, on the hydrogen peroxide (H(2)O(2))-induced oxidative stress and DNA damage in NIH3T3 cells. When the cells were treated with kahweol or cafestol, cytotoxicity, lipid peroxidation, and reactive oxygen species production induced by H(2)O(2) were markedly reduced in a dose-dependent manner. Moreover, kahweol and cafestol were shown to be highly protected against H(2)O(2)-induced oxidative DNA damage as determined by the Comet (single cell gel electrophoresis) assay and the measurement of 8-oxoguanine content in NIH3T3 cells. Kahweol and cafestol also protected hydroxyl radical-induced 2-deoxy-d-ribose degradation by ferric ion-nitrilotriacetic acid and H(2)O(2). In addition, kahweol and cafestol efficiently removed the superoxide anion generated from the xanthine/xanthine oxidase system. These results suggest that kahweol and cafestol are effective in protecting against H(2)O(2)-induced oxidative stress and DNA damage, probably via scavenging free oxygen radicals, and that kahweol and cafestol act as antioxidants.

On-line HPLC analysis of the antioxidant activity of phenolic compounds in brewed, paper-filtered coffee

Caffeoyl-, feruloyl- and dicaffeoylquinic acids (chlorogenic acids) in infusions from green and medium roasted coffee beans were identified and quantified by reverse phase HPLC with photodiode array and MS³ detection prior to assessment of the antioxidant activity using an HPLC system with post-column on-line antioxidant detection based on 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonic acid radical scavenging activity. Caffeoylquinic acids were the most abundant antioxidants and roasting induced isomerisation with a decline in 5-O-caffeoylquinic acid and concomitant increases in the 3- and 4-O-derivatives. This did not affect the level of caffeoylquinic acid-derived antioxidant activity in the roasted coffee. Roasting did, however, result in the appearance of additional unidentified HPLC peaks with antioxidant activity. Because of this and an increase in the antioxidant activity of components that did not elute from the reversed phase HPLC column, the antioxidant capacity of the beverage derived from medium roast beans was double that of the unroasted coffee. The antioxidant activity of coffees that have undergone different degrees of roasting would, therefore, appear to be due to combinations of different components. The effect of roasting on chlorogenic acids in coffee beans is considered, and the possible contribution of Maillard reaction products to the antioxidant capacity of roasted coffees is discussed.

Coffee consumption and human health--beneficial or detrimental?--Mechanisms for effects of coffee consumption on different risk factors for cardiovascular disease and type 2 diabetes mellitus

Coffee is probably the most frequently ingested beverage worldwide. Especially Scandinavia has a high prevalence of coffee-drinkers, and they traditionally make their coffee by boiling ground coffee beans and water. Because of its consumption in most countries in the world, it is interesting, from both a public and a scientific perspective, to discuss its potential benefits or adverse aspects in relation to especially two main health problems, namely cardiovascular disease and type 2 diabetes mellitus. Epidemiological studies suggest that consumption of boiled coffee is associated with elevated risk for cardiovascular disease. This is mainly due to the two diterpenes identified in the lipid fraction of coffee grounds, cafestol and kahweol. These compounds promote increased plasma concentration of cholesterol in humans. Coffee is also a rich source of many other ingredients that may contribute to its biological activity, like heterocyclic compounds that exhibit strong antioxidant activity. Based on the literature reviewed, it is apparent that moderate daily filtered, coffee intake is not associated with any adverse effects on cardiovascular outcome. On the contrary, the data shows that coffee has a significant antioxidant activity, and may have an inverse association with the risk of type 2 diabetes mellitus.

Possible repair action of Vitamin C on DNA damage induced by methyl methanesulfonate, cyclophosphamide, FeSO4 and CuSO4 in mouse blood cells in vivo

Interaction between Vitamin C (VitC) and transition metals can induce the formation of reactive oxygen species (ROS). VitC may also act as an ROS scavenger and as a metal chelant. To examine these possibilities, we tested in vivo the effect of two doses of VitC (1 and 30 mg/kg of mouse body weight) on the genotoxicity of known mutagens and transition metals. We used the alkaline version of the comet assay to assess DNA damage in peripheral white blood cells of mice. Animals were orally given either water (control), cyclophosphamide (CP), methyl methanesulfonate (MMS), cupric sulfate or ferrous sulfate. A single treatment with each VitC dose was administered after treatment with the mutagens or the metal sulfates. Both doses of VitC enhanced DNA damage caused by the metal sulfates. DNA damage caused by MMS was significantly reduced by the lower dose, but not by the higher dose of VitC. For CP, neither post-treatment dose of VitC affected the DNA damage level. These results indicate a modulatory role of Vitamin C in the genotoxicity/repair effect of these compounds. Single treatment with either dose of VitC showed genotoxic effects after 24 h but not after 48 h, indicating repair. Double treatment with VitC (at 0 and 24 h) induced a cumulative genotoxic response at 48 h, more intense for the higher dose. The results suggest that VitC can be either genotoxic or a repair stimulant, since the alkaline version of the comet assay does not differentiate "effective" strand breaks from those generated as an intermediate step in excision repair (incomplete excision repair sites). Further data is needed to shed light upon the beneficial/noxious effects of VitC.

Antioxidant properties of roasted coffee residues

The antioxidant activity of roasted coffee residues was evaluated. Extraction with four solvents (water, methanol, ethanol, and n-hexane) showed that water extracts of roasted coffee residues (WERCR) produced higher yields and gave better protection for lipid peroxidation. WERCR showed a remarkable protective effect on oxidative damage of protein. In addition, WERCR showed scavenging of free radicals as well as the reducing ability and to bind ferrous ions, indicating that WERCR acts as both primary and secondary antioxidants. The HPLC analyses showed that phenolic acids (chlorogenic acid and caffeic acid) and nonphenolic compounds [caffeine, trigonelline, nicotinic acid, and 5-(hydroxymethyl)furfuraldehyde] remained in roasted coffee residues. These compounds showed a protective effect on a liposome model system. The concentrations of flavonoids and polyphenolic compounds in roasted coffee residues were 8,400 and 20,400 ppm, respectively. In addition, the Maillard reaction products (MRPs) remaining in roasted coffee residues were believed to show antioxidant activity. These data indicate that roasted coffee residues have excellent potential for use as a natural antioxidant source because the antioxidant compounds remained in roasted coffee residues.

In vitro and ex vivo antihydroxyl radical activity of green and roasted coffee

The specific antiradical activity against the hydroxyl radical of the water soluble components in green and dark roasted Coffea arabica and Coffea robusta coffee samples, both in vitro by the chemical deoxiribose assay and ex vivo in a biological cellular system (IMR32 cells), were determined. All the tested coffee solutions showed remarkable antiradical activity. In the deoxiribose assay, all the tested solutions showed similar inhibitory activity (IA%) against the sugar degradation (IA values ranged from 45.2 to 46.9%). In the cell cultures, the survival increase (SI%) ranged from 197.0 to 394.0% with C. robusta roasted coffee being significantly more active than the other samples. The coffee solutions underwent dialysis (3500 Da cutoff membrane) to fraction their components. In both systems, the dialysates (MW < 3500 Da) either from green or roasted coffee, showed antiradical activity, while the only retentates (MW > 3500 Da) from the roasted coffee samples were active. The preparative gel-filtration chromatography of roasted coffee C. robusta dialysate gave three fractions active in the biological system, all containing chlorogenic acid derivatives. The most active fraction was found to be that containing the 5-O-caffeoilquinic acid, which shows a linear relation dose-response ranging from 0.02 to 0.10 mM. The results show that both green and roasted coffee possess antiradical activity, that their more active component is 5-O-caffeoyl-quinic acid, and moreover that roasting process induces high MW components (later Maillard reaction products, i.e., melanoidins), also possessing antiradical activity in coffee. These results could explain the neuroprotective effects found for coffee consumption in recent epidemiological studies.

The effects of coffee on enzymes involved in metabolism of the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in rats

The effects of coffee on the metabolism and genotoxicity of the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were investigated. Coffee diminished the bacterial mutagenicity of PhIP in the Ames reversion assay through inhibition of cytochrome P450 1A2 (CYP1A2), a key enzyme involved in the metabolic activation of PhIP. When given as part of the diet (0, 1 or 5% w/w) to male Fischer-344 rats for 2 weeks, coffee affected the expression of hepatic enzymes involved in PhIP metabolism. Coffee increased the expression of CYP1A2 by 16-fold in the 5% coffee-treated group, and approximately half of this inductive effect was attributed to caffeine. Coffee also increased the expression of enzymes involved in the detoxication of PhIP. A 2-fold increase in expression of glutathione S-transferase alpha was observed, UDP-glucuronosyl transferase (UGTs) activities of p-nitrophenol increased 2-fold, while N(2)-and N3-glucuronidation of the genotoxic metabolite 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (HONH-PhIP) increased by 1.3-fold in the 5% coffee-treated over the control group. The amount of PhIP (0.75 mg/kg, 24 h) eliminated in urine as the N(2)-and N3-glucuronide conjugates of HONH-PhIP increased by 1.8- and 2.5-fold, respectively, in the 5% coffee-treated group over control rats, suggesting either increased rates of N-oxidation of PhIP or N-glucuronidation of HONH-PhIP. Despite the strong induction of CYP1A2, there was no increase in PhIP-DNA adduct formation in colon and pancreas while liver adducts decreased by 50% over control animals. These data suggest that the effect of coffee on inhibition of PhIP N-oxidation and ensuing DNA damage is more important in vivo than its effect on induction of PhIP N-hydroxylation.

Changes in green coffee protein profiles during roasting

To reveal its flavor, coffee has to be roasted. In fact, the green coffee bean contains all ingredients necessary for the later development of coffee flavor. It is now widely accepted that free amino acids and peptides are required for the generation of coffee aroma. However, the mechanisms leading to defined mixtures of free amino acids and peptides remain unknown. Information pertaining to the identification of precursor proteins is also lacking. To answer some of these questions, two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) was used to follow the fate of green coffee proteins. Two conditions were considered: roasting and incubation of green coffee suspensions at 37 degrees C. Coffee beans were observed to acquire the potential to spontaneously release H(2)O(2) upon polymerization of their proteins during roasting. Fragmentation of proteins was also observed. Conversely, H(2)O(2) was found to control polymerization and fragmentation of green coffee proteins in solution at 37 degrees C. Polymerization and fragmentation patterns under the two conditions were comparable. These observations suggest that the two conditions under study triggered, at least to some extent, similar biochemical mechanisms involving autoxidation. Throughout this study, a unique fragmentation cascade involving the 11S coffee storage protein was identified. Generated fragments shared an atypical staining behavior linked to their sensitivity to redox conditions.

Antioxidant properties of ready-to-drink coffee brews

The influence of some technological variables on the changes of the antioxidant capacity of ready-to-drink coffee brews was investigated. Results showed that, depending on the roasting degree as well as on the packaging conditions adopted, redox reactions, which can take place during storage, are responsible for significant changes in the overall antioxidant capacity of the product. In particular, the redox potential of air-packaged coffee brews, obtained from light- and medium-roasted beans, showed maximum values after 2 days of storage, which corresponded to a minimum in the chain-breaking activity, while, in the case of the dark-roasted sample packaged under ordinary atmosphere, both the redox potential and the chain-breaking activity showed a maximum around 2-3 days of storage. In contrast, in the absence of oxygen, the coffee brews maintained the initial reducing properties over all the storage time, although the radical-scavenging activity values changed in a way very similar to that of the air-packaged sample. These results suggested that the changes in the antioxidant properties of the coffee brews may be attributed to a further development of the Maillard reaction during storage.

Characterization of free radicals in soluble coffee by electron paramagnetic resonance spectroscopy

EPR spectra of soluble coffee display single-line free radical signals in both the solid state and aqueous solution, along with signals from the paramagnetic ions Fe(III) and Mn(II). The intensity of the free radical signal in the pure solid was estimated to be ca. 7.5 x 10(16) unpaired electrons/g, and there was no significant change on dissolution in water. In aqueous solutions, however, the free radical signal declined rapidly over ca. 10-15 min in the temperature range 20-65 degrees C, after which only slow changes were observed. This decline, which was essentially independent of atmosphere, was greatest for the lowest temperatures used, and the intensity after 1 h fitted well to an exponential curve with respect to temperature. The free radicals responsible for the single-peak EPR signal did not react with any of the spin traps tested in the present experiments, but unstable free radicals with parameters consistent with adducts of C-centered radicals were detected in coffee solutions in the presence of PBN and 4-POBN spin traps. The presence of oxygen in the solutions increased the initial rate of formation of these free radical adducts. No adducts were detected when DEPMPO was used as spin trap. However, *OH adducts of DEPMPO were shown to be unstable in the presence of coffee, a fact which illustrates the strong free radical scavenging ability of coffee solutions.

Selective peroxynitrite scavenging activity of 3-methyl-1,2-cyclopentanedione from coffee extract

It has been known that reactive oxygen and nitrogen species such as nitric oxide (NO), superoxide radical (*O2-) and their byproduct peroxynitrite (ONOO-) induce cellular and tissue injury, ultimately resulting in several human diseases. In this study, we examined scavenging effects of 3-methyl-1,2-cyclopentanedione (MCP) from coffee extract on the reactivity of those toxic molecules. MCP significantly inhibited both the oxidation of 2,7-dichlorodihydrofluorescein diacetate (H2DCFDA) by reactive oxygen species (ROS) (mainly *O2-) from kidney homogenate (41% at 100 microM) and the generation of fluorescent 4,5-diaminofluorescein (DAF-2) by NO from sodium nitroprusside (IC50 (concn producing 50% inhibition), 63.8 microM). More potently, however, MCP suppressed the oxidation of dihydrorhodamine 123 (DHR 123) to fluorescent rhodamine 123 mediated by authentic ONOO- with an IC50 value of 3.3 microM. The neutralizing effect of the reactivity of ONOO- by MCP was due to electron donation, not nitration of the compound. Additionally, MCP also decreased ONOO- formation of nitrotyrosine adducts of glutathione (GSH) reductase, and consequently protected the enzyme activity of GSH reductase against decreasing by ONOO-, indicating that MCP may prevent ONOO- -induced damage of GSH reductase. Furthermore, MCP only weakly suppressed NO production, which is one of the upstream sources of ONOO- in-vivo, suggesting that NO production may be not a pharmacological target for MCP. Taken together, our results suggest that MCP may be regarded as a selective regulator of ONOO- -mediated diseases via direct scavenging activity of ONOO-.

Degradation of the coffee flavor compound furfuryl mercaptan in model Fenton-type reaction systems

The stability of the coffee flavor compound furfuryl mercaptan has been investigated in aqueous solutions under Fenton-type reaction conditions. The impact of hydrogen peroxide, iron, ascorbic acid, and ethylenediaminetetraacetic acid was studied in various combinations of reagents and temperature. Furfuryl mercaptan reacts readily under Fenton-type reaction conditions, leading to up to 90% degradation within 1 h at 37 degrees C. The losses were lower when one or more of the reagents was omitted or the temperature decreased to 22 degrees C. Volatile reaction products identified were mainly dimers of furfuryl mercaptan, difurfuryl disulfide being the major compound. In addition, a large number of nonvolatile compounds was observed with molecular masses in the range of 92-510 Da. The formation of hydroxyl and carbon-centered radicals was indicated by electron paramagnetic resonance spectra using alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone or 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide as spin traps. Whereas *OH was generated by Fenton-type reactions, the C-centered radical is probably a secondary product of the reaction of *OH with various organic molecules, the reaction with furfuryl mercaptan appearing to be the most important. No evidence for S-centered radicals was seen in the spin-trapping experiments, but a sulfur-containing radical was detected when measurements were made at 77 K in the absence of spin traps.

Sister chromatid exchange induced by several types of coffees in Chinese hamster ovary cells

Different brands of commercial caffeinated and decaffeinated coffees (roasted, high roast, blend ground, and instant coffees) were studied. These coffees were tested for their ability to induce sister chromatid exchanges (SCE) in CHO-K1 cells. Tests were performed in the presence and in the absence of a metabolic activation system (S-9 mix). Results were compared to the roasting procedure because genotoxic products could be formed from these processes. Our results indicate that caffeinated instant coffees showed higher genotoxic activity than decaffeinated coffees. Non-significant genotoxic activity was detected with the green coffee (unroasted). The highest increase of the frequency of SCE occurred when the caffeinated instant coffee was tested in the absence of metabolic activation system. The repeatability of the test was checked through three assays with the same sample.