Oxidative metabolism of 7-methylbenz[a]anthracene, 12-methylbenz[a]anthracene and 7,12-dimethylbenz[a]anthracene by rat liver cytosol.

Earlier studies from this laboratory demonstrated that benz[a]anthracene (BA), 7-methylbenz[a]anthracene (7-MBA) and 12-methylbenz[a]anthracene (12-MBA) undergo a bio-alkylation substitution reaction in the meso-anthracenic position(s) or L-region leading to the biosynthesis of the potent carcinogen 7,12-dimethylbenz[a]anthracene (7,12-DMBA). These results support the hypothesis that for most, if not all, unsubstituted polycyclic aromatic hydrocarbon carcinogens, the chemical or biochemical introduction of an alkyl group in the meso-anthracenic position(s) or L-region is a structural requirement for strong carcinogenic activity. Here we report that the L-region methyl derivatives 7-MBA, 12-MBA and 7,12-DMBA are oxidized to hydroxymethyl derivatives by a rat liver cytosol preparation without any apparent oxidation of the ring positions.