Inhibition of the genotoxic effects of heterocyclic amines in human derived hepatoma cells by dietary bioantimutagens.

The effects of dietary bioantimutagens (compounds which have been shown to inhibit mutagenesis via interaction with DNA repair processes) on spontaneous and heterocyclic amine (HCA)-induced micronucleus (MN) frequencies were studied in metabolically competent human hepatoma (Hep-G2) cells. All the compounds tested (coumarin, vanillin, caffeine, tannic acid and cinnamaldehyde) caused a moderate increase of MN numbers in Hep-G2 cells at high concentrations (500 microg/ml); only tannic acid was also active at lower dose levels. In combination experiments with the HCA 2-amino-3-methylimidazo-[3,4-f]quinoline (IQ), post-treatment of the cells with bioantimutagens resulted in a pronounced (75-90%) decrease in MN. The most drastic effects were seen with vanillin, coumarin and caffeine which were active at concentrations < or = 5 microg/ml. Further experiments indicated that these compounds also attenuate the mutagenic effects of other HCAs (PhIP, MeIQ, MeIQx, Trp-P-1).