BIO-ANTIMUTAGENIC ACTIVITY OF GREEN TEA CATECHINS IN CULTURED CHINESE-HAMSTER V79 CELLS

The antimutagenic effects of green tea catechins, (-)-epicatechin gall ate (ECg) and (-)-epigallocatechin gallate (EGCg) on induction of 6-th ioguanine (6TG)-resistant mutations induced by 4-nitroquinolin 1-oxide (4NQO) were found in cultured Chinese hamster V79 cells. The antimuta genic activity of catechins was found only when cells were post-treate d with catechins during the mutation expression time after treatment w ith 4NQO, and not found by simultaneous treatments with 4NQO and catec hins. This bioantimutagenic activity of catechins were not observed in ethyl methanesulfonate (EMS)-induced mutations. This suggests that th e antimutagenic effects of catechins may act intracellularly as bio-an timutagenic blocking agent or suppressive agent. These catechins had n o effects on the cytotoxic activity of 4NQO in V79 cells, whether cate chins were used in simultaneous treatment with or in post-treatment af ter 4NQO. This indicates that the antimutagenicity and anticytotoxicit y to 4NQO may be caused by different mechanism(s).