Inhibition of in vivo genotoxicity by coffee

Antioxidant and Anti-Inflammatory Activity of Coffee Brew Evaluated after Simulated Gastrointestinal Digestion

Coffee contains human health-related molecules, namely polyphenols that possess a wide range of pharmacological functions, and their intake is associated with reduced colon cancer risk. This study aimed to assess the changes in the anti-inflammatory and antioxidant activity of coffee after simulated gastrointestinal digestion. The evaluation of intracellular reactive oxygen species (ROS) levels in the HT-29 human colon cancer cell line and three in vitro spectrophotometric assays were performed to determine the antioxidant activity of the samples. Characterization of coffee composition was also assessed through a Q-Orbitrap high-resolution mass spectrometry analysis. The results highlighted that the levels of polyphenols in the digested coffee brews were higher than those of the non-digested ones. All assayed samples decreased the levels of intracellular ROS when compared to untreated cells, while digested coffee samples exhibited higher antioxidant capacity and total phenolic content than not-digested coffee samples. Digested coffee samples showed a higher reduction in interleukin-6 levels than the not-digested samples in lipopolysaccharide-stimulated HT-29 cells treated for 48 h and fewer cytotoxic effects in the MTT assay. Overall, our findings suggest that coffee may exert antioxidant and anti-inflammatory properties, and the digestion process may be able to release compounds with higher bioactivity.

Genotoxic Assessment of the Dry Decoction of Myracrodruon urundeuva Allemão (Anacardiaceae) Leaves in Somatic Cells of Drosophila melanogaster by the Comet and SMART Assays

Medicinal plants are worldwide used as an efficient treatment of many diseases. Myracrodruon urundeuva Allemão (Anacardiaceae) is widely used Brazilian folk medicine to treat inflammations and infections of the female genital tract, conditions of the stomach and throat, and to heal wounds on the skin and mucous membranes. Several pharmacological properties of extracts and compounds isolated from M. urundeuva are found in the literature, corroborating its uses as antiulcer and gastroprotective, anti-inflammatory and analgesic, as well as antimicrobial. Despite these many uses in traditional herbal medicine, there are few reports of its toxic-genetic effect. This work aimed to investigate the genotoxic and mutagenic potential in vivo of the dry decoction of M. urundeuva leaves on somatic cells of Drosophila melanogaster, through the Comet assay and somatic mutation and recombination test (SMART). Six concentrations (0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 mg/mL) were studied after feeding individuals for 24 hr in culture medium hydrated with extracts of M. urundeuva. In the Comet assay, all concentrations showed a genotoxic effect significantly higher than the negative control group, treated with distilled water. The two highest concentrations were also superior to the positive control group, treated with cyclophosphamide (1 mg/mL). In the SMART, there was a mutagenic effect at all concentrations tested, with a clear dose-dependent relationship. Both recombination and mutation account for these mutagenic effects. The set of results indicate that the dry decoction of M. urundeuva leaves is genotoxic and mutagenic for D. melanogaster under the experimental conditions of this study. Environ. Mol. Mutagen. 61:329-337, 2020. © 2019 Wiley Periodicals, Inc.

Assessment of Cellular Mutagenicity of Americano Coffees from Popular Coffee Chains

Coffee is a popular beverage worldwide, but coffee beans can be contaminated with carcinogens. The Ames Salmonella mutagenicity test is often used for analysis of carcinogens for mutagenicity. However, previous studies have provided controversial data about the direct mutagenicity of coffee beans based on Ames test results. This study was conducted to determine the mutagenicity of popular Americano coffee based on results from the Ames test. Coffee samples without additives that were served by five international coffee chain restaurants were subjected to the analysis using Salmonella Typhimurium tester strains TA98, TA100, and TA1535. The levels of bacterial revertants in samples from coffee chains were lower than the twofold criterion of the control sets, and no significant dose-response effect was observed with or without rat liver enzyme activation. These data indicate that Americano coffees from the selected coffee chains possessed no direct mutagenic activity with or without enzyme activation. These findings suggest a low mutagenic risk from Americano coffees served by the selected coffee chains and support the use of other methods to confirm the nonmutagenicity of coffee products. These results are consistent with most recent epidemiological reports.

Intake of saffron reduces γ-radiation-induced genotoxicity and oxidative stress in mice

Saffron (SAF), the dried stigmas of Crocus sativus, is commonly used for flavoring and coloring food. Studies on bioactivity of SAF have demonstrated its in vivo antioxidant activity. The aim of our study was to assess the impact of SAF intake on γ-radiation (RAD) induced (a) chromosomal damage, (b) oxidative stress in liver and brain, and (c) histopathological effects in the intestinal cells and male germ cells in mice. Freeze-dried aqueous extract of SAF was used for the experiments. Our preliminary cell-free DNA nicking assay using pBR322 DNA revealed protective effects of freeze-dried SAF extract against hydroxyl radical induced DNA damage. For the in vivo investigations, freeze-dried SAF extract in distilled water was administered by gavage (40 mg/kg b.w.) to male Swiss albino mice for six consecutive days. On the sixth day, the animals were exposed to RAD (1 or 2 Gy) and sacrificed 24 h later to collect bone marrow cells for assessing chromosomal damage by measuring micronucleated polychromatic erythrocytes (MnPCEs). Liver and brain samples from animals exposed to 2 Gy RAD were used for evaluating lipid peroxidation and activity of antioxidant enzymes. The testis and intestine were used for histopathological analysis. Our results demonstrated significant protective effects of SAF against RAD-induced genotoxic damage. SAF pretreatment reduced the level of lipid peroxidation with concomitant increase in glutathione content and activity of glutathione S-transferase, glutathione peroxidase, and catalase. The histopathological analysis showed minimal impact of SAF on RAD-induced damage in the intestinal cells and male germ cells.

Protecting effect of caffeine against vinblastine (an anticancer drug) induced genotoxicity in mice

Vinblastine a DNA non-intercalating agent has wide application against several human neoplasms, and found to cause cytogenotoxicity. In this study, clastogenotoxicity of vinblastine (1.5 mg/kg b w) and its prevention by caffeine at different doses (25, 50 and 100 mg/kg b w) administered intraperitoneally was assessed in in vivo mice. It was found that micronucleus level had decreased significantly (up to 28.8%) in 100 mg caffeine treated group at 30 h post treatment. However, it did not exhibit protective effect against chromosomal aberration in spaermatogonial cells at 24 h post treatment. The frequencies of aberrant primary spermatocytes had decreased significantly in 25 and 100 mg caffeine at 4th week of post treatment. Similarly, in 100 mg of caffeine administered, abnormal sperm level had reduced (4.01%) significantly at 8th week post treatment. Thus, caffeine decreased the vinblastine induced chromosomal aberrations and mitotic index in bone marrow cells. In conclusion, this study shows that caffeine exerts protective effect against vinblastin induced cytogenotoxicity. Further studies on molecular mechanism are interesting in order to develop it as an effective drug in cancer chemotherapy.

Protective effect of caffeine on ethyl methanesulfonate-induced wing primordial cells of Drosophila melanogaster

OBJECTIVES

The antimutagenic effect of caffeine is evaluated against ethyl methanesulfonate (EMS)-induced mutation rate in Drosophila.

MATERIALS AND METHODS

The mutation rate is evaluated using wing mosaic assay. In transheterozygous larvae, multiple wing hair (mwh 0.3-3) and flare (flr 3-38.8) genes were used as markers of the extent of mutagenicity.

RESULTS

The results at 0.5 and 1.0 mM EMS concentration at both 48 ± 4 and 72 ± 4 h have shown consistent increase in mutation rate, which was being measured as frequency of clone formation per 105 cells. Toxicity of caffeine at 5 mM concentration was parallel to that of distilled water alone. At 0.5 mM EMS concentration at 42 ± 4 and 72 ± 4 h, Drosophila larvae mutation rate was significantly increased. Although caffeine prevented mutation rate in all pre, post, and combined treatment, it was more significant in pretreatment experiments where it was found to be effective in reducing the genotoxicity of EMS. However, the concentration of caffeine as recommended in dietary allowance did not induce the frequency of mutant clones in somatic mutation and recombination test (SMART) recorded.

CONCLUSION

This study shows that caffeine significantly reduced the genotoxicity induced by EMS. However, the limitation in completely abolishing genotoxicity induced by EMS as observed at the dietary allowance of caffeine makes it interesting for further in-depth study. Further studies on the molecular mechanism of antigenotoxic effect of caffeine will also be interesting.

Dietary factors and risk of t(14;18)-defined subgroups of non-Hodgkin lymphoma

OBJECTIVE

To evaluate the associations between diet and non-Hodgkin lymphoma (NHL) according to t(14;18) status, one of the most common chromosomal abnormalities in NHL, as t(14;18)-positive NHL represents a genetically more homogeneous group than NHL overall.

METHODS

We determined the presence of the t(14;18)(q32;q21) by fluorescence in situ hybridization in 172 of 175 tumor blocks from a population-based, case-control study conducted in Nebraska during 1983-1986. Information on the frequency of consumption as an adult of 30 food items was derived from the parent case-control study. Dietary factors in 60 t(14;18)-positive and 87 t(14;18)-negative cases were compared with 1,075 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using polytomous logistic regression.

RESULTS

The risk of t(14;18)-positive NHL for the highest versus the lowest approximate tertile of intake was elevated for milk (OR = 2.2; 1.0-5.0) and dietary nitrite (OR = 2.8; 1.3-6.1), whereas coffee consumption was inversely associated with risk (OR = 0.4; 0.2-0.7). We also found inverse associations between the intake of fish (OR = 0.5; 0.3-1.0) and carotene (OR = 0.5; 0.2-0.9) and risk of t(14;18)-negative NHL. There was no association between the intake of meats, vegetables, protein, or vitamin C and risk of either t(14;18)-positive or t(14;18)-negative NHL.

CONCLUSION

We observed differences in associations between diet and t(14;18)-defined subgroups of NHL. These findings should be interpreted cautiously because of the small sample.

Protective effect of tomato against N-methyl-N'-nitro-N-nitrosoguanidine-induced in vivo clastogenicity and oxidative stress

OBJECTIVE

Chemoprevention by dietary constituents has emerged as a cost-effective approach to control the incidence of gastric cancer, the second most common malignancy worldwide, and a major cause of mortality in Chennai, India. Identification of dietary agents with chemopreventive potential requires prescreening in animal models. We evaluated the modifying effects of tomato paste against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced genetic damage and oxidative stress in male Swiss mice.

METHODS

Quantitation of bone marrow micronuclei, extent of lipid peroxidation, and the status of the antioxidants reduced glutathione, glutathione peroxidase, and glutathione S-transferase in the stomach and liver of Swiss albino mice were used to monitor the protective effects of tomato. Three different doses of tomato (0.5, 1, and 2 g/kg of body weight) were administered intragastrically for 5 d consecutively followed by intragastric intubation of MNNG 1.5 h after the final administration.

RESULTS

Increased frequency of micronuclei and enhanced lipid peroxidation were accompanied by compromised antioxidant defenses in MNNG-treated rats. Pretreatment of tomato paste at the concentration of 1 and 2 g/kg of body weight significantly decreased micronuclei and lipid peroxidation and enhanced reduced glutathione-dependent antioxidant and detoxifying enzymes.

CONCLUSION

Our results demonstrate that tomato protects against the clastogenic effects of MNNG by decreasing micronucleated polychromatic erythrocytes and lipid peroxidation and enhancing antioxidant status.

Attenuation of N-methyl-N'-nitro-N-nitrosoguanidine induced genotoxicity and oxidative stress by tomato and garlic combination

The protective effect of pretreatment with tomato and garlic against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced genotoxicity and oxidative stress was investigated in male Swiss mice. In vivo bone marrow micronucleus test was performed to assess the antigenotoxic effect of tomato and garlic. Oxidative stress was monitored by estimating the extent of lipid peroxidation and the status of the glutathione redox cycle antioxidants. Increased frequency of bone marrow micronuclei with enhanced lipid peroxidation was associated with compromised antioxidant defenses in MNNG treated animals. Although pretreatment with tomato and garlic significantly reduced the frequencies of MNNG-induced bone marrow micronuclei, the combination of tomato and garlic exerted a greater protective effect. This was associated with modulation of lipid peroxidation as well as reduced glutathione (GSH) and the GSH-dependent enzymes glutathione peroxidase (GPx) and glutathione-S-transferase (GST). These findings suggest that a diet containing even low levels of different naturally occurring compounds is effective in exerting antigenotoxic effects by modulating oxidative stress.

Protective effects of ethanolic neem leaf extract on N-methyl-N'-nitro-N-nitrosoguanidine-induced genotoxicity and oxidative stress in mice

We evaluated the effects of pretreatment with ethanolic neem leaf extract on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced genotoxicity and oxidative stress in male Swiss albino mice. The frequency of micronuclei (MN), concentrations of lipid peroxides and the status of the antioxidants, reduced glutathione (GSH), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were used as intermediate biomarkers of chemoprotection. Animals were divided into four groups of five animals each. Animals in group 1 were given MNNG (40 mg/kg body weight) by intragastric intubation. Animals in group 2 received intragastric administration of ethanolic neem leaf extract at a concentration of 200 mg/kg body weight for 5 days followed by MNNG 1.5 h after the final feeding. Group 3 animals received ethanolic neem leaf extract alone for five days. Group 4 received the same volume of normal saline and served as control. The animals were sacrificed by cervical dislocation 27 h after the carcinogen exposure. In MNNG-treated mice, enhanced lipid peroxidation with compromised antioxidant defences in the stomach, liver and erythrocytes was accompanied by increase in bone marrow micronuclei. Pretreatment with ethanolic neem leaf extract significantly reduced MNNG-induced micronuclei and lipid peroxides and enhanced GSH-dependent antioxidant activities. The results of the present study demonstrate that ethanolic neem leaf extract exerts protective effects against MNNG-induced genotoxicity and oxidative stress by augmenting host antioxidant defence mechanisms.

Anti-genotoxicity of coffee against N-methyl-N-nitro-N-nitrosoguanidine in mouse lymphoma cells

The main aim of this work was to test the hypothesis that instant coffee, a commonly consumed polyphenolic beverage with antioxidant activity, can protect mammalian cells against genotoxic effects in vitro. For this purpose, the L5178Y mouse lymphoma cell line was selected to assess modulatory effects of coffee on the genotoxicity of N-methyl-N-nitro-N-nitrosoguanidine (MNNG). We initiated the work with a set of preliminary experiments in which the cytokinesis-block micronucleus test was performed. Results obtained from these experiments demonstrated a dose-related decrease in genotoxicity following co-treatment of mouse lymphoma cells with three doses of caffeinated instant coffee. Both pre-treatment and co-treatment showed significant antigenotoxic effects against MNNG. Caffeinated and decaffeinated instant coffee samples inhibited genotoxicity. There was no significant change in the antigenotoxic effect of caffeinated instant coffee after filtration using a 0.2 microm filter. Similar in vitro experiments demonstrated antigenotoxic effects against MNNG when boiled coffee was used instead of instant coffee. On the basis of the findings from the above preliminary experiments, further work was carried out to evaluate the possible protective effects of caffeinated instant coffee against MNNG-induced DNA damage, mutation and chromosomal damage. Results from three or five independent experiments demonstrated significant protective effects of caffeinated instant coffee against MNNG-induced DNA damage in the comet assay, mutation at the Tk locus and chromosomal damage in the cytokinesis-block micronucleus test.

Protection of N-methyl-N'-nitro-N-nitrosoguanidine-induced in vivo clastogenicity by aqueous garlic extract

The modulatory effects of garlic extract on the in vivo clastogenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a carcinogenic nitrosamine, were evaluated by quantification of micronuclei and chromosomal aberrations in metaphase cells from the bone marrow of male Wistar rats. A single intraperitoneal injection of MNNG (40 mg/kg bodyweight) was found to be clastogenic as revealed by the increased frequency of micronucleated polychromatic erythrocytes and chromosomal aberrations. Pretreatment with aqueous garlic extract (250 mg/kg bodyweight) for 5 days significantly reduced the frequencies of MNNG-induced micronuclei and chromosomal aberrations. The results demonstrate that administration of garlic extract protects against the clastogenic effects of MNNG.

Inhibition of genotoxicity by saffron (Crocus sativus L.) in mice

Experiments were carried out to ascertain whether or not saffron (dried stigmas of Crocus sativus L.), a commonly used agent for flavoring and coloring food can exert modulatory effects on the in vivo genotoxicity of cisplatin (CIS), cyclophosphamide (CPH), mitomycin C (MMC) and urethane (URE). For this purpose, Swiss albino mice were pretreated for five consecutive days with three doses (20, 40 and 80 mg/kg body weight) of the aqueous extract of saffron. Genotoxic effects were assessed in the mouse bone marrow micronucleus test. The results obtained suggest that pretreatment with saffron can significantly inhibit the genotoxicity of CIS, CPH, MMC and URE. This inhibitory effect was not always dose-dependent. In addition, the hepatic glutathione S-transferase (GST) activity was assessed in the control and treated animals. No significant change in GST activity was observed after pretreatment with saffron alone. Treatment with the genotoxins alone significantly inhibited GST activity. Saffron pretreatment attenuated the inhibitory effects of the genotoxins on GST activity.

Anti-genotoxicity of trans-anethole and eugenol in mice

The naturally occurring flavouring agents trans-anethole and eugenol were evaluated for antigenotoxic effects in mice. The test doses of trans-anethole (40-400 mg/kg body weight) and eugenol (50-500 mg/kg weight) were administered by gavage 2 and 20 h before the genotoxins were injected intraperitoneally. Anti-genotoxic effects were assessed in the mouse bone marrow micronucleus test. Pretreatment with trans-anethole and eugenol led to significant antigenotoxic effects against cyclophosphamide (CPH), procarbazine (PCB), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and urethane (URE). In addition, trans-anethole inhibited the genotoxicity of ethyl methane sulfonate (EMS). Both trans-anethole and eugenol exerted dose-related antigenotoxic effects against PCB and URE. There was no significant increase in genotoxicity when trans-anethole (40-400 mg/kg body weight) and eugenol (50-500 mg/kg body weight) were administered alone.

Modulatory effects of garlic and neem leaf extracts on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced oxidative stress in Wistar rats

The effects of garlic and neem leaf extracts on lipid peroxidation and antioxidant status during administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a carcinogenic nitrosamine were evaluated in male Wistar rats. Extracts of garlic and neem leaf were administered orally for five consecutive days before intraperitoneal injection of MNNG. Enhanced lipid peroxidation in the stomach, liver and circulation of MNNG-treated rats was accompanied by a significant decrease in glutathione (GSH) and the activities of glutathione peroxidase (GPx), glutathione-S-transferase (GST) and gamma glutamyl transpeptidase (GGT). Administration of garlic and neem leaf extracts significantly decreased the formation of lipid peroxides and enhanced the levels of antioxidants and detoxifying enzymes in stomach, the primary target organ for MNNG, as well as in the liver and circulation. The results of the present study suggest that garlic and neem may exert their protective effects by modulating lipid peroxidation and enhancing the levels of GSH and GSH-dependent enzymes.

Anti-genotoxicity and glutathione S-transferase activity in mice pretreated with caffeinated and decaffeinated coffee

In vivo anti-genotoxic effects of caffeinated and decaffeinated instant coffee were compared in mice after pretreatment either by gavage for 10 consecutive days or in the drinking water for 2 weeks. Changes in hepatic sulfhydryl (-SH) content and glutathione S-transferase (GST) activity were evaluated in pretreated animals. Both caffeinated and decaffeinated instant coffee induced a moderate increase in -SH content and GST activity following pretreatment (with 70, 140 and 280 mg/kg body weight) by gavage for 10 days. This enhancement was not always dose dependent. The maximum effect on GST activity was observed at a dose of 140 mg/kg body weight/day. However, such an effect was not observed after administration of drinking water containing 2% caffeinated/decaffeinated instant coffee for 2 weeks. Results of the bone marrow micronucleus test for evaluating genotoxic effects revealed that both caffeinated and decaffeinated instant coffee (140 mg/kg body weight/day) could exert significant anti-genotoxic effects against ip injected benzo[a]pyrene (BP), cyclophosphamide (CPH), 7,12-dimethylbenz[a]anthracene (DMBA), mitomycin C (MMC) and procarbazine (PCB) in animals pretreated by gavage. Anti-genotoxic effects against BP, DMBA and urethane (URE) were evaluated in animals that received drinking water containing 2% caffeinated/decaffeinated instant coffee for 2 weeks. With the exception of the anti-genotoxic effect of decaffeinated coffee against DMBA, there was no significant change in genotoxicity after the above pretreatment. From this work, there is no evidence for any significant difference in the in vivo anti-genotoxicity of caffeinated and decaffeinated instant coffee.

Genotoxicity of instant coffee: possible involvement of phenolic compounds

Instant coffee exhibits direct genotoxic activity in the tester strains TA 98, 100, 102, 104 and YG 1024. In the Ames tester strain TA 100, the presence of S9 mix, S100 mix, S9 mix without cofactors led to a significant decrease of the genotoxicity observed. The decrease observed in the presence of S9 mix seems to be highly correlated with the catalase content of S9 mix. The genotoxicity of instant coffee detected in strain TA 100 was dependent on the pH, with higher genotoxic effects at pH values above neutrality. Also, dependent on the pH was the ability of some phenolic molecules present in coffee promoting the degradation of deoxyribose in the presence of Fe3+/EDTA. These results suggest that apart from other molecules present in instant coffee responsible for their genotoxicity in several short term assays, phenolic molecules could also be implicated in the genotoxicity of coffee, via reactive oxygen species arising from its auto-oxidation.

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.

In vivo antigenotoxic effects of dietary agents and beverages co-administered with urethane: assessment of the role of glutathione S-transferase activity

Antigenotoxic effects and changes in glutathione S-transferase (GST) activity were assessed in mice after oral co-administration of urethane (URE) with aqueous extracts of dietary vegetables (carrot, spinach and cabbage), spices (cinnamon, pepper, cumin, clove and cardamom), tea and coffee. The results of the genotoxicity assay (micronucleus test) demonstrated dose-related antigenotoxic effects after URE was co-administered with aqueous extracts of vegetables, spices, tea and coffee. Inhibition of GST activity was observed 4 h after treatment with URE alone. Co-administration of URE with extracts of vegetables, coffee and spices resulted in dose-related attenuation of the inhibitory effect of URE on GST activity. However, tea had no effect on inhibition of GST activity by URE. Hence an association between antigenotoxicity and GST activity could not be established.

Anti-genotoxic effects in mice after the interaction between coffee and dietary constituents

The interaction between coffee (100 mg freeze-dried home brew/kg body weight) and dietary constituents was assessed for anti-genotoxic effects against cyclophosphamide, N-methyl-N-nitro-N- nitrosoguanidine (MNNG), N-nitroso-N-ethylurea, mitomycin C and urethane (URE) in the mouse bone marrow micronucleus test. Combinations of dietary constituents consisting of (1) chlorogenic acid, caffeic acid, ellagic acid and ferulic acid, (2) beta-carotene, curcumin and alpha-tocopherol, (3) chlorogenic acid, curcumin, alpha-tocopherol, anethole and eugenol, and (4) beta-carotene, curcumin, ellagic acid and chlorogenic acid were used in this study. Before the genotoxin was injected i.p., identical groups of mice were orally administered either vehicle control, coffee, dietary constituents, or coffee plus dietary constituents. Co-administration of coffee with the dietary constituents enhanced the anti-genotoxic effect compared with that of either coffee or the dietary constituents alone. Two-factor analysis of variance of the data suggests that there is a significant synergistic interaction between coffee and the dietary constituents for anti-genotoxic effects against MNNG (combination 1 and 2) and URE (combination 4).

Protection by coffee against somatic genotoxicity in Drosophila: role of bioactivation capacity

The protective effects of coffee against somatic mutation and mitotic recombination induced by cyclophosphamide (CPH), mitomycin C (MMC) and urethane (URE) were evaluated in the standard (ST) and high bioactivation (HB) crosses of the wing spot test in Drosophila melanogaster. These two crosses are characterized by different constitutive levels of cytochrome )-450-dependent enzyme activities. 3-day old larvae transheterozygous for the wing cell markers mwh (multiple wing hairs) and flr3 (flare3) were fed until pupation on medium containing a genotoxin alone or its combination with different concentrations of instant coffee. subsequently, the wings of the resulting adult flies were analysed for detecting single spots (mwh or flr3) originating from mutational or recombinational events as well as twin spots (mwh and flr3) originating exclusively from recombination. The results showed high sensitivity of the HB cross to URE. Co-administration of instant coffee was effective in exerting significant dose-related inhibitory effects on the genotoxicity of URE in the ST and the genetically susceptible HB cross. Similarly, coffee showed significant dose-related inhibitory effects on the genotoxicity of MMC in both crosses. The same protective effect was also observed with one concentration of coffee in combination with CPH. Pretreatment of 2-day-old HB larvae with coffee for 24 hr followed by treatment with URE was also effective in significantly reducing the induction of mutation and recombination. The magnitude of the protective effects of coffee against these three genotoxins was independent of the genotype of the larvae used for treatment, that is it was independent of the bioactivation capacity of these larvae. The study demonstrates the suitability of this assay for obtaining qualitative and quantitative data on the result of interactions among a genotoxin, an inhibitor of genotoxicity and bioactivation capacity of the host.

Inhibitory effects of coffee on transplacental genotoxicity in mice

Experiments were carried out to ascertain whether or not coffee can modulate the genotoxicity of transplacentally active genotoxins/carcinogens. Coffee was orally administered to Swiss albino mice (gestation, 15-16 days), 90 min before exposure to cyclophosphamide (CPH), N-nitrosodiethylamine (DEN), N-nitroso-N-ethylurea (ENU) and mitomycin C (MMC). At the end of the treatment, the induction of micronucleated polychromatic erythrocytes (MnPCEs) was evaluated in the fetal liver (FL), fetal blood (FB) and maternal bone marrow (MBM). The results of this transplacental micronucleus test showed a consistent trend which suggests that the administration of coffee instead of water (control) can significantly inhibit the genotoxic effects of CPH, DEN, ENU and MMC in the FL and FB. When the fetal cells were evaluated either 22 and 28 h after CPH treatment, or 24 and 48 h after MMC treatment, there was no evidence for a significant interaction between the sampling time and the inhibitory effect of coffee (two-factor ANOVA). However, a significant interaction was observed between sampling time and the inhibitory effects of coffee when the fetal cells were sampled 24 and 40 h after DEN treatment (two-factor ANOVA). Coffee was also effective in significantly inhibiting the genotoxicity of CPH, ENU and MMC in the MBM. The differential response of fetal and maternal target cells was evident from this study.

Analysis of the potential carcinogenicity of coffee and its related compounds in a medium-term liver bioassay of rats

The potential carcinogenicity of coffee and related compounds was examined using a medium-term liver bioassay based on the induction of glutathione S-transferase placental form (GST-P)-positive foci in F344 rats. A total of 230 males were initially injected with diethylnitrosamine (200 mg/kg body weight, ip) or saline as controls and 2 wk later were fed on diet or drinking water supplemented as follows for 6 wk: 5% regular instant coffee; 5% decaffeinated instant coffee; freshly brewed coffee, 8 g in 140 ml water; 0.1% caffeine, 0.2% methylglyoxal, 0.2% glyoxal; or 0.3% theophylline in the drinking water (w/v); and 0.4% theobromine in the diet (w/w). All rats were subjected to two-thirds partial hepatectomy at wk 3 and killed at wk 8. The resultant values for GST-P-positive hepatic focus induction were slightly increased with methylglyoxal and decreased with glyoxal and theobromine compared with the corresponding controls. Although the increase in number of foci for methylglyoxal was statistically significant at P < 0.05, the value was within the historical control levels. Regular and decaffeinated instant coffee as well as fresh-brewed coffee, caffeine and theophylline exerted no effects on focus development. Thus, the coffee-related compounds examined demonstrated no obvious enhancing potential, and it is therefore concluded that coffee and its main constituents are not carcinogenic for the rat liver.

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

Hydrogen peroxide (H2O2) has been implicated as a major contributor to coffee mutagenicity and genotoxicity in vitro. We have used three assays to show the gradual formation of H2O2 in freshly prepared roasted ground coffee and in instant coffees over time reaching levels of 400-450 microM after a 1-h incubation period. Formation of H2O2 occurs through an auto-oxidation process where polyphenolics, in the presence of transition metals, reduce atmospheric oxygen. However, because of these polyphenolics, coffee also possesses in vitro antioxidant activity as shown by its capacity to inhibit lipid peroxidation in Fenton-catalysed hydroxylation reactions. The pro- and antioxidative effects of coffee are also reflected in its mutagenic and antimutagenic activity in the Ames test. Coffee is directly mutagenic in strains TA100 and TA102 due to H2O2 formation. However, coffee is also an antioxidant and antimutagen. This beverage exerts a strong protective effect against the mutagenicity and cytotoxicity induced by the oxidant t-butylhydroperoxide (t-BOOH). Thus, coffee, like many antioxidants, exhibits dual effects in vitro which are highly dependent upon parameters such as dose, atmospheric oxygen, transition metals as well as the biological and chemical endpoints used for measurement. Consequently, the data obtained on the pro- and antioxidant properties of foods and beverages from in vitro bioassays must be interpreted with caution and the results are not easily extrapolated in vivo to assess the impact on human health.

Genotoxicity testing of different types of beverages in the Drosophila wing Somatic Mutation And Recombination Test

Five wines and one brandy of Spanish origin as well as three herbal teas and ordinary black tea were tested for genotoxicity in the wing Somatic Mutation And Recombination Test (SMART) which makes use of the two recessive wing cell markers multiple wing hairs (mwh) and flare (flr3) on the left arm of chromosome 3 of Drosophila melanogaster. 3-day-old larvae trans-heterozygous for these two markers were fed the beverages at different concentrations and for different feeding periods using Drosophila instant medium. Somatic mutations or mitotic recombinations induced in the cells of the wing imaginal discs give rise to mutant single or twin spots on the wing blade of the emerging adult flies showing either the mwh phenotype or/and the flr phenotype. One of the red wines showed a clear genotoxic activity that was not due to its ethanol content. Two herbal teas (Urtica dioica, Achillea millefolium) and black tea (Camellia sinensis) proved to be weakly genotoxic as well. Furthermore, it was shown that quercetin and rutin, two flavonols present in beverages of plant origin, also exhibited weak genotoxic activity in the somatic cells of Drosophila. These results demonstrate that Drosophila in vivo somatic assays can detect the genotoxicity of complex mixtures such as beverages. In particular, it is possible to administer these test materials in the same form as that in which they are normally consumed.

Effect of dietary caffeic and chlorogenic acids on in vivo xenobiotic enzyme systems

The plant phenols chlorogenic and caffeic acids were tested for their affinity to alter hepatic and intestinal xenobiotic Phase I and Phase II enzyme activities in mice. Mice were fed isocaloric and isonitrogenous powdered diets containing 0 and 0.2% caffeic and chlorogenic acids, respectively. Animals pre-treated with benzo(a)pyrene (B(a)P) were sacrificed 18 h after an oral dose (50 mg/kg Bwt). B(a)P induced animals exhibited higher (p < 0.05) microsomal AHH, UDPGT, P-450 and cytosolic GST liver enzyme activities. The presence of these phenolics in the diet was shown to have little effect in modulating hepatic xenobiotic activating-detoxification enzymes. The dietary intake of caffeic and chlorogenic acids was particularly evident with intestinal xenobiotic AHH and GST enzyme activity. These data indicate that the presence of caffeic and chlorogenic acids in the diet may have an integral role in modulating the carcinogenic potential of reactive xenobiotics such as B(a)P.

Potential genotoxic, mutagenic and antimutagenic effects of coffee: a review

Coffee and caffeine are mutagenic to bacteria and fungi, and in high concentrations they are also mutagenic to mammalian cells in culture. However, the mutagenic effects of coffee disappear when bacteria or mammalian cells are cultured in the presence of liver extracts which contain detoxifying enzymes. In vivo, coffee and caffeine are devoid of mutagenic effects. Coffee and caffeine are able to interact with many other mutagens and their effects are synergistic with X-rays, ultraviolet light and some chemical agents. Caffeine seems to potentiate rather than to induce chromosomal aberrations and also to transform sublethal damage of mutagenic agents into lethal damage. Conversely, coffee and caffeine are also able to inhibit the mutagenic effects of numerous chemicals. These antimutagenic effects depend on the time of administration of coffee as compared to the acting time of the mutagenic agent. In that case, caffeine seems to be able to restore the normal cycle of mitosis and phosphorylation in irradiated cells. Finally, the potential genotoxic and mutagenic effects of the most important constituents of coffee are reviewed. Mutagenicity of caffeine is mainly attributed to chemically reactive components such as aliphatic dicarbonyls. The latter compounds, formed during the roasting process, are mutagenic to bacteria but less to mammalian cells. Hydrogen peroxide is not very active but seems to considerably enhance mutagenic properties of methylglyoxal. Phenolic compounds are not mutagenic but rather anticarcinogenic. Benzopyrene and mutagens formed during pyrolysis are not mutagenic whereas roasting of coffee beans at high temperature generates mutagenic heterocyclic amines. In conclusion, the mutagenic potential of coffee and caffeine has been demonstrated in lower organisms, but usually at doses several orders of magnitude greater than the estimated lethal dose for caffeine in humans. Therefore, the chances of coffee and caffeine consumption in moderate to normal amounts to induce mutagenic effects in humans are almost nonexistent.

Radioprotection by caffeine pre- and post-treatment in the bone marrow chromosomes of mice given whole-body gamma-irradiation

The effect of caffeine given as pre- and post-treatment in mice exposed to whole-body gamma-irradiation (1.5 Gy 60Co gamma-rays) was studied. The pre-treatment was either acute or chronic. The acute dose (5 mg/kg and 15 mg/kg body weight) was in the form of an injection given intraperitoneally, 30 min before irradiation. The chronic administration was in the form of caffeine solution (4.208 x 10(-3) M and 7.72 x 10(-4) M) contained in the drinking water that mice had had ad libitum access to instead of plain drinking water for 5 weeks prior to radiation exposure. The acute pre-treatment with caffeine reduced the radiation-induced frequency of chromosomal aberrations discernibly, whereas the chronic pre-treatment afforded a much more significant degree of radioprotection. The caffeine post-treatment (5 mg/kg and 15 mg body weight) was given in the form of an intraperitoneal injection to the mice immediately following whole-body gamma-irradiation. It is noted that both post-treatment concentrations of caffeine also significantly reduced the frequency of chromosomal aberrations induced by gamma-rays. These data are briefly discussed in terms of possible mechanistic considerations.

An update on research with coffee/caffeine (1989-1990)

The interest in research with coffee has been increasing in recent years, and this has resulted in a surge of publications dealing with a variety of pharmaco-physiological effects of coffee/caffeine. This review attempts to update the information on the research with coffee/caffeine, including epidemiological studies, laboratory investigations and tests with volunteers, published in 1989 and 1990. It groups published articles according to observed or investigated biological effects. The most significant findings and differences between studies are pointed out with brief commentaries on the results. The overall assessment for the safety of drinking coffee and the effect of coffee on human health, based on the literature published in 1989 and 1990, indicates that certain controversial issues are still unresolved.

Inhibitory effects of coffee on the genotoxicity of carcinogens in mice

The mouse bone marrow micronucleus test was carried out to evaluate the possible inhibitory effects of 3 doses (125, 250 and 500 mg/kg) of standard instant coffee on the in vivo genotoxicity of 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (BP), aflatoxin B1 (AFB1) and urethane (UR). Coffee was orally administered twice, 2 and 20 h before the carcinogens were injected intraperitoneally. From the results obtained, it was evident that the administration of 250 and 500 mg coffee/kg body weight could significantly inhibit the in vivo genotoxicity of these carcinogens. A linear dose response was observed for the inhibitory effect of coffee. Furthermore, inhibition of genotoxicity by coffee was observed in bone marrow cells which were sampled at 6-h intervals (48, 54, 60, 66 and 72 h) from the time of peak induction of micronuclei by DMBA.

Inhibition by coffee of nitrosourea-mediated DNA damage in mice

Oral administration of coffee at doses ranging from 150 mg to 1 g per kg body weight significantly decreased endogenously formed nitrosourea-mediated DNA damage in bone marrow as well as in colon epithelial cells in mice that had simultaneously received oral administration of methylurea and sodium nitrite. Since coffee (1 g/kg body weight) did not decrease DNA damage when administered orally together with performed methylnitrosourea, it was hypothesized that coffee inhibits nitrosation in the stomach of mice. The lowest effective level of coffee, when compared on the basis of body weight, corresponds to a human intake of about 5 cups of coffee. Both chlorogenic acid (150 mg/kg body weight) and premelanoidins (1 g/kg body weight), which occur as ingredients in, or are formed during roasting of, coffee, were shown to inhibit nitrosourea-induced DNA damage in mice.