Ames mutagenicity tests of overheated brewed coffee

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.

Trigonelline, a naturally occurring constituent of green coffee beans behind the mutagenic activity of roasted coffee?

Trigonelline and amino acids are natural components in green coffee beans. Model systems mimicking coffee roasting were used to produce heated samples of trigonelline, amino acids and glucose. Trigonelline and amino acids were heated separately or in combinations for 20 min at 250 degrees C. The results of bacteria mutation assays (Salmonella typhimurium strains TA 98, YG 1024 and YG 1029) showed that trigonelline, alone or in combination with most of the single amino acids and mixtures of amino acids, yielded potent mutagenic activity. Of the singly heated compounds, the highest mutagenic activity was found for trigonelline. The mutagenic activity detected with metabolic activation of the heated trigonelline samples indicated that the mutagenic compounds might be amines; however, higher mutagenic activity was found for trigonelline and its combinations without metabolic activation, which suggests that other types of mutagens (direct-acting) were predominant. High-performance liquid chromatographic analysis of some of the heated samples did not reveal the presence of any known mutagenic heterocyclic amine.

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.

Characterization of mutagenic activity in instant hot beverage powders

Extracts of several grain-based coffee-substitute blends and instant coffees were mutagenic in the Ames/Salmonella test using TA98, YG1024, and YG1029 with metabolic activation. The beverage powders induced 150 to 500 TA98 and 1,150 to 4,050 YG1024 revertant colonies/g, respectively. Increased sensitivity was achieved using strain YG1024. No mutagenic activity was found in instant hot cocoa products. The mutagenic activity in the beverage powders was shown to be stable to heat and the products varied in resistance to acid nitrite treatment. Differential bacterial strain specificity, and a requirement for metabolic activation suggest that aromatic amines are present. Characterization of the mutagenic activity, using HPLC and the Ames test of the collected fractions, showed the coffee-substitute blends and instant coffees contain several mutagenic compounds. Known heterocyclic amines are not responsible for the major part of the mutagenic activity. The main mutagenic activity in grain-based coffee-substitute blends and instant coffees is due to several unidentified compounds, which are most likely aromatic amines.

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.

Medicinal plant inventory of Kuna Indians: Part 1

Results of an ethnopharmacognostic survey of 90 plants used by the Kuna Indians of San Blas Islands, who live in Ailigandí, are listed. Results of a literature search are also reported, including medical uses, known constituents and pharmacological effects.

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.

Biological and chemical studies on overheated brewed coffee

Vapour formed from overheated decaffeinated coffee was condensed and tested for mutagenicity using the Ames assay in Salmonella typhimurium strains TA98 and TA100. Vapour produced at 73 and 100 degrees C exhibited no mutagenicity. The basic fraction of vapour produced at 350 degrees C showed weak mutagenicity towards strains TA98 with metabolic activation. The chemical analysis of this fraction identified pyridines and pyrazines as the major constituents. None of the compounds identified in this fraction has been reported as mutagenic when tested in the Ames assay.

Investigation of coffee in Drosophila genotoxicity tests

Two preparations of coffee (instant coffee and freeze-dried home-brew coffee) were tested in different mutagenicity assays in germ cells as well as in somatic cells of Drosophila melanogaster. The three end-points assayed in germ cells were sex-linked recessive lethals (mainly gene mutations and small chromosome aberrations), dominant lethals (cytotoxic effects as well as genotoxic effects) and sex-chromosome losses (chromosome breakage and non-disjunction). The aqueous coffee solutions were fed either to adult male flies for 3 days or to growing larvae during the whole larval development. Treated males were crossed with appropriately marked females, and the different genetic end-points were analysed in the F1 or F2 generation. The test concentrations (instant coffee 4% (w/v), home-brew coffee 3%) were acutely toxic in adult males (killing approximately 75 and 90% of the exposed flies, respectively). No increase in deaths was caused in larvae by the same concentrations. Only cytotoxic effects were observed in the test for dominant lethals. No conclusive genotoxic effects could be detected in any of the three germ cell assays. The coffee preparations were also tested for induction of mutation and mitotic recombination in somatic cells of the wing imaginal disc. Larvae trans-heterozygous for two recessive wing hair markers were fed high concentrations of the coffees for varying periods of time. Wings of surviving adult flies were analysed for mosaic spots. Twin spots exhibiting both mutant phenotypes are produced by mitotic recombination; single spots showing one or the other phenotype are the result of somatic mutation, such as gene mutation or deletion, or of mitotic recombination. Both coffees had weak effects on normal (repair-proficient) cells as well as on excision repair-defective cells in this assay. Additional experiments with pure caffeine and decaffeinated coffee show that these weak effects in somatic cells were most probably caused by the caffeine present in the two coffees.

New aspects on the chemistry of tea and coffee. III

The previous review for 1983/1984 is now continued with references to recent publications (1984/1985) and as before covers the chemistry and technology of tea (leaf, green and black) and coffee (raw, roasted and instant soluble), with particular reference to composition and changes during manufacture, extraction and storage. The effects of composition on the quality of the beverage, with mention of particular physiological properties, are included (210 references).