Author(s): Hour TC, Liang YC, Chu IS, Lin JK, Hour TC, Liang YC, Chu IS, Lin JK
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Abstract The antimutagenic properties of various tea extracts (green tea, pauchong tea, oolong tea and black tea) and their components including (-)-epigallocatechin-3-gallate (EGCG), gallic acid and caffeine were examined by the Ames test. The antimutagenic activity of the green tea extract against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), folpet and monocrotophos was greater than those of pouchong, oolong and black tea extracts. The antimutagenic effects of tea extracts against 2-acetylaminofluorene (AAF) decreased as follows: oolong tea > pauchong tea > black tea > green tea. Furthermore, black tea showed a greater antimutagenic activity against benzo[a]pyrene (BP). The pauchong tea showed a stronger inhibitory effect against 9-aminoacridine (9AA) and aflatoxin B1 (AFB1) than other tea extracts. EGCG markedly suppressed the direct-acting mutagenicity of MNNG, N-nitroso-N-methylurea (MNU), captan, and folpet which were alkylating agents and fungicides. Similarly, gallic acid, the major component of black tea strongly inhibited the mutagenicity of 9AA, and moderately inhibited the mutagenicity of MNNG and folpet. The caffeine was less active. EGCG and gallic acid perhaps could act as nucleophiles to scavenge the electrophilic mutagens. Taken together, these results suggest that formation of different metabolites during various stages of tea fermentation may affect antimutagenic potencies against different types of chemical mutagens.
This article was published in Food Chem Toxicol
and referenced in Journal of Cancer Science & Therapy