Multiple metabolic pathways for the mutagenic activation of 3-nitrobenzo[a]pyrene.

Rat liver microsomal metabolism of the potent mutagen 3-nitrobenzo[a]pyrene (3-nitro-BaP) under aerobic conditions yielded 3-nitro-BaP trans-7,8-dihydrodiol and 3-nitro-BaP trans-9,10-dihydrodiol, and under anaerobic conditions produced 3-amino-BaP. All of these metabolites were highly mutagenic in the Salmonella typhimurium reversion assay both with and without exogenous metabolic activation (S9). None of the in vitro metabolic pathways led to detoxification of 3-nitro-BaP.