MECHANISM OF ANTIMUTAGENIC ACTION OF (-CATECHIN AGAINST THE PLANT-ACTIVATED AROMATIC AMINE 4-NITRO-O-PHENYLENEDIAMINE())

Aromatic amines are activated into mutagens by both animal and plant s ystems. For plant-activated aromatic amines an important step in this process involves peroxidase enzymes. 4-nitro-o-phenylenediamine (NOP) is a well known direct-acting mutagen that can be enhanced in mutageni c potency by intact plant cells and also by isolated peroxidase enzyme s. This activation process is inhibited by several different chemical agents including potassium cyanide (KCn), a known peroxidase inhibitor , and (+)-catechin. In our laboratory both KCn and (+)-catechin inhibi ted peroxidase-mediated NOP activation into a Salmonella mutagen. Howe ver, while KCn demonstrated strong peroxidase enzyme inhibition (as me asured biochemically), (+)-catechin showed only minimal inhibition of peroxidase. Experiments comparing NOP direct and plant-activated mutag enic activity to different Salmonella strains (in the presence and abs ence of (+)-catechin) suggest that (+)-catechin may inhibit the mutage nic process by limiting O-acetyltransferase (OAT) activity in Salmonel la. OAT activity in Salmonella is a required process for mutations to be induced following treatment with NOP and other aromatic amines.