PLANT-ACTIVATION OF THE BICYCLIC AROMATIC-AMINES BENZIDINE AND 4-AMINOBIPHENYL

Benzidine and 4-aminobiphenyl (4-ABP) are promutagenic bicyclic aromat ic amines that are activated into frameshift and base pair substitutio n mutagens by plant systems. Using the plant cell/microbe coincubation assay, plant-activated benzidine from 0 to 50 mu M induced a concentr ation-response in Salmonella typhimurium. At concentrations above 5 mu M plant-activated benzidine induced frameshift and base pair substitu tion mutations in the N- or O-acetyltransferase over-expressing strain s, DJ460, YG1024, and YG1029. With plant-activated 4-ABP, concentratio ns above 250 mu M induced a significant mutagenic response in strains YG 1024 and YG 1029. A tobacco cell-free mixture, TX1MX, activated ben zidine and 4-ABP Into mutagenic metabolites in S. typhimurium strains YG1024, YG1029, and DJ460. The mutagenic sensitivities of plant-activa ted benzidine and 4-ABP were the some with two different types of plan t activation systems, TX1 sus pension cells and TX1MX cell-free medium . The plant activation of these aromatic amines is mediated by tobacco cell peroxidase. Plant-activated benzidine and 4-ABP are converted in to intermediates that serve as substrates for bacterial or humanacetyl CoA: N-hydroxyarylamine N-acetyltransferase to generate the ultimate m utagenic products. (C) 1997 Wiley-Liss, Inc.