Suppression of genotoxicity of carcinogens by (-)-epigallocatechin gallate. |
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Authors: | H Hayatsu N Inada T Kakutani S Arimoto T Negishi K Mori T Okuda I Sakata |
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Institution: | Faculty of Pharmaceutical Sciences, Okayama University, Japan. |
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Abstract: | Epidemiological evidence shows that green tea may be a factor in lowering cancer risk. We have investigated the possibility that (-)-epigallocatechin gallate (EGCG), a major polyphenol in green tea, might be an antimutagenic substance. In the Ames Salmonella test, EGCG suppressed the direct-acting mutagenicity of 3-hydroxyamino-1-methyl-5H-pyrido-4,3-b]indole (Trp-P-2(NHOH)) and 2-hydroxyamino-6-methyldipyrido1,2-a:3',2'-d]imidazole (Glu-P-1(NHOH)), the activated forms of food-derived carcinogens 3-amino-1-methyl-5H-pyrido4,3-b]indole and 2-amino-6-methyldipyrido1,2-a:3',2'-d]imidazole. EGCG was also effective in reducing the mutagenicity of Trp-P-2(NHOH) in mouse FM3A cells in culture. Furthermore, EGCG demonstrated a suppressive effect in the in vivo Drosophila mutation assays, i.e., the wing spot test, and the DNA repair test, on several carcinogens. EGCG was also effective in inhibiting DNA single-strand breaks in vitro caused by Glu-P-1(NHOH). We conclude that the mechanism of inhibition may not have resulted from direct interaction between EGCG and the mutagens, but rather from indirect interception of mutagen action by EGCG. |
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