Suppressive effects of coffee on the SOS responses induced by UV and chemical mutagens

SOS-inducing activity of UV or chemical mutagens (AF-2, 4NQO and MNNG) was strongly suppressed by instant coffee in Salmonella typhimurium TA1535/pSK1002. As decaffeinated instant coffee showed a similarly strong suppressive effect, it would seem that caffeine, a known inhibitor of SOS responses, is not responsible for the effect observed. The suppression was also shown by freshly brewed coffee extracts. However, the suppression was absent in green coffee-bean extracts. These results suggest that coffee contains some substance(s) which, apart from caffeine, suppresses SOS-inducing activity of UV or chemical mutagens and that the suppressive substance(s) are produced by roasting coffee beans.     

咖啡和绿茶的抗氧化活性研究

茶和咖啡是全世界消费最多的饮料。该工作利用电子自旋共振(ESR)技术和ABTS〔2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid)〕等方法,研究和比较了3种绿茶(龙井、碧螺春和毛峰)和3种咖啡的抗氧化活性,以及对ABTS 、DPPH、超氧阴离子、羟基自由基、单线态氧的清除作用和对脂质过氧化的抑制作用。利用高压液相色谱(HPLC)分析了绿茶中的抗氧化成分之一EGCG((-)-epigallocatechin gallate)和咖啡中的抗氧化成分之一绿原酸(chlorogenic acid5,CQA)的含量。结果发现,如果按每克剂量比较,对于清除ABTS 的能力而言,茶和咖啡水提取液对ABTS 清除能力各有千秋,咖啡水提取液的比龙井、毛峰水提取液的高,但与碧螺春无显著差异,咖啡B比咖啡A和C强;按每杯茶(3g/200mL)和咖啡(2.4g/200mL)对ABTS 的清除能力进行比较,咖啡的比龙井和毛峰的高但比碧螺春低,咖啡B比咖啡A和C强。对超氧阴离子、羟基和DPPH自由基及单线态氧的清除作用和对脂质过氧化的抑制作用的研究表明,如果按每克剂量比较,茶和咖啡水提取液没有明显区别;按每杯量进行比较时,茶水提取液比咖啡水提取液对自由基的清除能力稍强。HPLC结果表明,EGCG含量在毛峰中最高,5CQA含量在咖啡B中最高。该研究结果表明茶和咖啡中均含有丰富的抗氧化成分,并都具有较强的抗氧化活性和清除自由基能力。     

Coffee-mediated protective effects against directly acting genotoxins and gamma-radiation in mouse lymphoma cells

The cytokinesis-block micronucleus test was performed using L5178Y mouse lymphoma cells to ascertain whether or not standard (caffeinated) instant coffee, the commonly consumed polyphenolic beverage with antioxidant activity can protect against chromosomal damage induced by the directly acting agents N-methyl-N-nitro-N-nitrosoguanidine (MNNG), mitomycin C (MMC), methyl methanesulfonate (MMS) and gamma radiation. Our results demonstrated significant reductions in the in vitro genotoxic effects of MNNG, MMC, and MMS following co-treatment of mouse lymphoma cells with standard instant coffee. Subsequently, the comet assay was carried out to assess the effect of coffee co-treatment on the level of DNA damage induced by MMS in mouse lymphoma cells. The results demonstrated a significant reduction in MMS-induced DNA damage following co-treatment with standard instant coffee. Protective effects were observed in mouse lymphoma cells which were treated with coffee immediately after exposure to gamma radiation (1 and 2 Gy). Another experiment showed protection when the mammalian cells were irradiated (0.5 and 1 Gy) midway (at 2 h) during a 4 h coffee treatment. However, the protective effect against the lower dose (0.5 Gy) was not significant. In addition we assessed the modulatory effect of coffee on MNNG-induced apoptotic frequency by flow cytometry. The results revealed only a minor influence of coffee on the frequency of apoptotic cells induced by the test compounds, rendering an increase in sensitivity for apoptosis as a reason for the reduced genomic damage an unlikely or at least incomplete explanation.     

Roasting coffee beans produces compounds that induce prophage lambda in E. coli and are mutagenic in E. coli and S. typhimurium

Freshly brewed blended coffee, instant coffee and instant caffeine-free coffee induced prophage lambda in lysogenic E. coli K12, strain GY5027. Because coffee prepared from green beans by the same extraction method as used for freshly brewed blended coffee had no prophage-inducing activity, this activity may be attributed to compounds produced in the roasting process. Roasting also produced compounds that were mutagenic in S. typhimurium TA100 and E. coli WP2 uvrA/pKM101.     

Inhibitory effect of serum from rats administered with coffee on the proliferation and invasion of rat ascites hepatoma cells

The action of coffee on the proliferation and invasion of a rat ascites hepatoma cell line of AH109A was investigated using in vitro and ex vivo assay systems. When rats were given oral intubation of instant coffee powder solution, the sera of those rats had the potent inhibitory activity on both the proliferation and invasion of AH109A. The activity of rat serum was both time- and dose-dependent. The instant coffee powder also inhibited the proliferation and invasion of AH109A in vitro. These results indicate that coffee has anti-proliferative and anti-invasive activity both in vitro and ex vivo. They also suggest that some anti-proliferative and anti-invasive material(s), which may be the ingredient(s) of coffee or their metabolites, appear in rat serum when rats are given oral intubation of coffee, although a possibility that host defense systems may be activated by the oral intubation of coffee cannot be ruled out. This revised version was published online in June 2006 with corrections to the Cover Date.     

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.     

Instant coffee extract with high chlorogenic acids content inhibits hepatic G‐6‐Pase in vitro,but does not reduce the glycaemia

Coffee is the main source of chlorogenic acid in the human diet, and it contains several chlorogenic acid isomers, of which the 5‐caffeoylquinic acid (5‐CQA) is the predominant isomer. Because there are no available data about the action of chlorogenic acids from instant coffee on hepatic glucose‐6‐phosphatase (G‐6‐Pase) activity and blood glucose levels, these effects were investigated in rats. The changes on G‐6‐Pase activity and liver glucose output induced by 5‐CQA were also investigated. Instant coffee extract with high chlorogenic acids content (37.8%) inhibited (p < 0.05) the G‐6‐Pase activity of the hepatocyte microsomal fraction in a dose‐dependent way (up to 53), but IV administration of this extract did not change the glycaemia (p > 0.05). Similarly, 5‐CQA (1 mM) reduced (p < 0.05) the activity of microsomal G‐6‐Pase by about 40%, but had no effect (p > 0.05) on glucose output arising from glycogenolysis in liver perfusion. It was concluded that instant coffee extract with high content of chlorogenic acids inhibited hepatic G‐6‐Pase in vitro, but failed to reduce the glycaemia probably because the coffee chlorogenic acids did not reach enough levels within the hepatocytes to inhibit the G‐6‐Pase and reduce the liver glucose output. Copyright © 2015 John Wiley & Sons, Ltd.     

Caffeine restriction: effect on mild hypertension.

OBJECTIVE--To determine the effects on blood pressure of modifying dietary caffeine intake in patients with mild and borderline hypertension by monitoring ambulatory and clinic blood pressure. DESIGN--Four way, randomised, crossover trial of four consecutive two week dietary regimens: normal diet, caffeine free diet alone, caffeine free diet with decaffeinated instant coffee, caffeine free diet with caffeinated instant coffee (instant coffee phases conducted double blind). SETTING--Hospital hypertension clinic, Scotland. PATIENTS--52 patients (23 men; aged 26-67 years) with untreated borderline or mild hypertension (diastolic blood pressure 90-105 mm Hg) who normally drank a minimum of three cups of coffee daily. MAIN OUTCOME MEASURES--Mean ambulatory blood pressure over 24 hours; mean morning, daytime, and night time ambulatory blood pressure; sitting clinic blood pressure at 1700; plasma caffeine concentration at 1700 on the last day of each regimen. RESULTS--Mean 24 hour ambulatory blood pressure was not different between regimens. There was no difference in blood pressure variability between regimens. During the caffeine free diet alone morning ambulatory diastolic blood pressure was higher (2.8 mm Hg) than during the caffeine free diet with caffeinated coffee. Mean sitting clinic systolic blood pressure was higher at 1700 (4.7 mm Hg) with a caffeine free diet than with the caffeine free diet with caffeinated coffee (p less than 0.05). Dietary compliance as assessed by plasma caffeine concentration was excellent. There was no significant correlation between plasma caffeine concentration and blood pressure. CONCLUSIONS--Drinking caffeinated instant coffee over a two week period does not adversely influence blood pressure in patients with borderline or mild hypertension; abstinence is of no benefit.     

Sulfite suppresses the mutagenic property of coffee

The mutagenicity of instant and freshly brewed coffee on Salmonella typhimurium TA100 and TA98 without S9 mix was inactivated by sodium sulfite. Sulfite ion at a dose of 200 ppm almost completely inactivated the mutagenicity of coffee made in the ordinary way (5-15 mg dry weight/ml). Sodium bisulfite and potassium metabisulfite had similar effects. On the contrary, L-ascorbic acid enhanced the mutagenicity of coffee. Sodium sulfite also inactivated the phage-inducing activity of coffee in inductest III. Sodium sulfite completely suppressed the mutagenicities of 1,2-dicarbonyls, namely diacetyl and glyoxal. Diacetyl is present in coffee, beer, butter and other foods and drinks. Because sodium sulfite, sodium bisulfite and potassium metabisulfite are widely used as food additives, they should be useful in reducing the levels of mutagens in foods.     

Study of the causes of direct-acting mutagenicity in coffee and tea using the Ara test in Salmonella typhimurium

The mutagenic activities of 6 of the chemicals identified in coffee solutions were assayed with the Salmonella Ara test, under experimental conditions optimized for coffee mutagenicity. Caffeine was the only non-mutagenic compound. Among the other 5 chemicals, hydrogen peroxide was the strongest mutagen and chlorogenic acid the weakest; methylglyoxal, glyoxal and caffeic acid exhibited intermediate mutagenicities. The minimal mutagenic doses of these components correlated negatively with their relative concentrations in coffee. It was concluded that chlorogenic acid, caffeic acid, glyoxal and methylglyoxal cannot contribute alone to the mutagenicity of coffee in the Ara test, since their minimal mutagenic concentrations were much higher than their respective levels in the coffee samples assayed. By contrast, 40-60% of the mutagenic activity in coffee and also in tea could be attributed to their H2O2 contents. Catalase abolished more than 95% of the mutagenic activity of coffee, as detected by the Ara test. A similar sensitivity to catalase has been reported by other authors in relation to the coffee mutagenicity identified by the Salmonella His test. Nevertheless, the results presented in this paper suggest that the Ara forward and the His reverse mutation tests are sensitive to the mutagenicity of different constituents in coffee solutions. We propose that the His test, sensitive at high coffee doses, mainly recognizes the mutagenicity of methylglyoxal, whilst the Ara test, sensitive at low coffee doses, mainly detects the mutagenic activity of hydrogen peroxide. The data reported also suggest that the direct-acting mutagenicity(ies) detected by the Ara test in tea solutions is (are) based on similar, if not identical, mechanisms.     

Biosynthesis of plant hormones during anaerobic digestion of instant coffee waste

A large amount of solid waste remains after the production of instant coffee. This waste has to be moved to dumps, where it poses a threat of environmental pollution. Treatment of this waste by anaerobic methanogenic thermophilic digestion produced, besides biogas, a digested slurry which was used as a growth medium for horticulture, and proved to be a suitable and economical substitute for peat moss. Biological tests with mung bean cuttings and Grevillea plantlets showed promotional effects on rooting of the slurry and its sieved fraction extract, washed with water (Capul). Green coffee beans, instant coffee waste, its anaerobically-digested slurry and Capul were extracted by various methods and the extracts were analyzed by TLC, HPLC and GC/MS. Examinations showed clearly the presence of IAA and IBA in free and bound forms in all the substrates. The values of free and bound IAA were calculated by use of an internal standard and GC/MS. The amount of conjugated IAA was found to be much higher than that of free IAA, in both the coffee beans and instant coffee waste (11.1 vs 2.7 nmol g^–1, respectively). In the digested slurry and Capul, however, most of the IAA was present as the free form and was approximately 23.5–33.0 nmol g^–1, which is almost ten times more than in the waste, and almost twice the total amount of IAA in coffee beans. It is postulated that the high levels of free IAA in the digested instant coffee waste are a result of catabolism of tryptophan by anaerobic bacteria.     

Mutagenicity of instant coffee and its interaction with dimethylnitrosamine in the micronucleus test

The mutagenicity of instant coffee and its interaction with dimethylnitrosamine (DMN) were examined in mice using the micronucleus test. Although neither a single nor multiple administration of instant coffee by gavage induced a significant rise in micronucleated cells over the dose range tested (100-2500 mg/kg), there was a tendency for the number of micronucleated cells to increase in a dose-related fashion. When coffee was administered with DMN, the difference in the frequency of micronucleated cells was small in comparison to a single treatment with DMN alone, thus indicating a lack of synergism between coffee and DMN.     

Characteristics of major mutagenicity of instant coffee

Detailed quantitative studies on the mutagenicity of methylglyoxal showed that its contribution to the total mutagenicity of instant coffee on S. typhimurium TA100 was minor although we reported previously (Kasai et al., 1982) that its contribution to the mutagenicity of freshly brewed coffee was about 50%. Cysteine suppressed the mutagenicity of methylglyoxal and of methylglyoxal when added to instant coffee, but did not affect the mutagenicity of coffee itself. Catalase suppressed most of the mutagenicity of coffee, but not that of methylglyoxal or of methylglyoxal added to coffee.     

Polyphenoloxidase activity in coffee leaves and its role in resistance against the coffee leaf miner and coffee leaf rust

In plants, PPO has been related to defense mechanism against pathogens and insects and this role was investigated in coffee trees regarding resistance against a leaf miner and coffee leaf rust disease. PPO activity was evaluated in different genotypes and in relation to methyl-jasmonate (Meja) treatment and mechanical damage. Evaluations were also performed using compatible and incompatible interactions of coffee with the fungus Hemileia vastatrix (causal agent of the leaf orange rust disease) and the insect Leucoptera coffeella (coffee leaf miner). The constitutive level of PPO activity observed for the 15 genotypes ranged from 3.8 to 88 units of activity/mg protein. However, no direct relationship was found with resistance of coffee to the fungus or insect. Chlorogenic acid (5-caffeoylquinic acid), the best substrate for coffee leaf PPO, was not related to resistance, suggesting that oxidation of other phenolics by PPO might play a role, as indicated by HPLC profiles. Mechanical damage, Meja treatment, H. vastatrix fungus inoculation and L. coffeella infestation caused different responses in PPO activity. These results suggest that coffee resistance may be related to the oxidative potential of the tissue regarding the phenolic composition rather than simply to a higher PPO activity.     

Implication of hydrogen peroxide in the mutagenicity of coffee

A cup of instant coffee (150 ml) of normal strength (15 mg/ml) was found to contain about 500 and 750 micrograms of hydrogen peroxide soon after its preparation at 37 degrees C and 80 degrees C, respectively, but the concentration of hydrogen peroxide in the coffee increased with time for up to 24 h after its preparation. Thus coffee contains a hydrogen peroxide generating system. As extracts of green coffee beans were found to have very low capacity to generate hydrogen peroxide, this generating system is produced by roasting coffee beans. Hydrogen peroxide itself was only weakly mutagenic to Salmonella typhimurium TA100, but in the presence of methylglyoxal, which is also present as a mutagenic component in coffee, hydrogen peroxide showed strong mutagenicity. Hydrogen peroxide and methylglyoxal seem to be responsible for most of the mutagenicity of instant coffee.     

Loss of heterocyclic amine mutagens by insoluble hemicellulose fiber and high-molecular-weight soluble polyphenolics of coffee

The presence of 2 kinds of components in brewed and instant coffee that could remove and destroy heterocyclic amine mutagens was demonstrated. The component that could remove the mutagens was insoluble fiber composed of hemicellulose. The fiber could tightly adsorb the mutagens Trp-P-1, Trp-P-2, Glu-P-1 and A alpha C, and those generated in roasted coffee beans. The component that could destroy the mutagens was high-molecular-weight soluble polyphenolics. They might be converted into quinone derivatives in the presence of molecular oxygen. The quinone derivatives might destroy the mutagens. The fibers and the polyphenolics in one cup of brewed or instant coffee had the capacity to remove and destroy a substantial amount of the mutagens in pyrolysates of foodstuffs.     

Antioxidant and free radical scavenging properties of N-acetylcysteine amide (NACA) and comparison with N-acetylcysteine (NAC)

The antioxidant potential of N-acetylcysteine amide (NACA), also known as AD4, was assessed by employing different in vitro assays. These included reducing power, free radical scavenging capacities, peroxidation inhibiting activity through linoleic acid emulsion system and metal chelating capacity, as compared to NAC and three widely used antioxidants, alpha-tocopherol, ascorbic acid and butylated hydroxytoluene (BHT). Of the antioxidant properties that were investigated, NACA was shown to possess higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging ability and reducing power than NAC, at all the concentrations, whereas the scavenging ability of H(2)O(2) differed with concentration. While NACA had greater H(2)O(2) scavenging capacity at the highest concentration, NAC was better than NACA at lower concentrations. NAC and NACA had a 60% and 55% higher ability to prevent beta-carotene bleaching, respectively, as compared to control. The chelating activity of NACA was more than 50% that of the metal chelating capacity of EDTA and four and nine times that of BHT and alpha-tocopherol, respectively. When compared to NACA and NAC; alpha-tocopherol had higher DPPH scavenging abilities and BHT and alpha-tocopherol had better beta-carotene bleaching power. These findings provide evidence that the novel antioxidant, NACA, has indeed enhanced the antioxidant properties of NAC.     

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.     

The Anaplasma phagocytophilum‐occupied vacuole selectively recruits Rab‐GTPases that are predominantly associated with recycling endosomes

Anaplasma phagocytophilum is an obligate intracellular bacterium that infects neutrophils to reside within a host cell‐derived vacuole. The A. phagocytophilum‐occupied vacuole (ApV) fails to mature along the endocytic pathway and is non‐fusogenic with lysosomes. Rab GTPases regulate membrane traffic. To better understand how the bacterium modulates the ApV's selective fusogencity, we examined the intracellular localization of 20 green fluorescent protein (GFP) or red fluorescent protein (RFP)‐tagged Rab GTPases in A. phagocytophilum‐infected HL‐60 cells. GFP‐Rab4A, GFP‐Rab10, GFP‐Rab11A, GFP‐Rab14, RFP‐Rab22A and GFP‐Rab35, which regulate endocytic recycling, and GFP‐Rab1, which mediates endoplasmic reticulum to Golgi apparatus trafficking, localize to the ApV. Fluorescently tagged Rabs are recruited to the ApV upon its formation and remain associated throughout infection. Endogenous Rab14 localizes to the ApV. Tetracycline treatment concomitantly promotes loss of recycling endosome‐associated GFP‐Rabs and acquisition of GFP‐Rab5, GFP‐Rab7, and the lysosomal marker, LAMP‐1. Wild‐type and GTPase‐ deficient versions, but not GDP‐restricted versions of GFP‐Rab1, GFP‐Rab4A and GFP‐Rab11A, localize to the ApV. Strikingly, GFP‐Rab10 recruitment to the ApV is guanine nucleotide‐independent. These data establish that A. phagocytophilum selectively recruits Rab GTPases that are primarily associated with recycling endosomes to facilitate its intracellular survival and implicate bacterial proteins in regulating Rab10 membrane cycling on the ApV.     

Coffee pulp koji of Aspergillus sojae as stable immobilized catalyst of chlorogenate hydrolase

Chlorogenate hydrolase (EC 3.1.1.42, CHase) was highly induced in mycelia of Aspergillus sojae AKU 3312 grown in Czapek medium containing either instant coffee powder or coffee pulp as inducer. No CHase formation was observed in the mycelia when cultivated without the inducer. CHase was purified readily from CHase-induced mycelia to high homogeneity, and the purified CHase revealed the molecular weight of 180,000 consisting of two identical subunits of 88 kDa. Equimolar quinate (QA) and caffeate (CA) were confirmed on hydrolysis of chlorogenate (CGA). The purified CHase was only useful for a laboratory scale hydrolysis of CGA. For practical QA and CA production using scaled up hydrolysis of vegetable extracts of natural CGA resources, the enzyme activity of purified CHase decreased and denatured irreversibly. Preparation of coffee pulp koji and its application to QA and CA production were proposed instead of purified CHase. When coffee pulp koji was heated at 60°C for 30 min, CHase survived without any appreciable loss of enzyme activity while vegetative mycelial growth and spore germination were terminated. The heated coffee pulp koji thus prepared was effective itself as stable immobilized catalyst of CHase for QA and CA production from vegetable CGA resources such as coffee powders, coffee pulp, and others.