The metabolic activation of benzo(a)pyrene and 9-hydroxybenzo (a) pyrene by liver microsomal fractions

Abstract

A rat liver microsome‐mediated bacterial mutagenicity test showed 9‐hydroxybenzo (a) pyrene to be significantly more effective as a pre‐mutagen than benzo (a) pyrene. Experiments measuring the ability of these compounds to be metabolically activated to moieties that alky late exogenous DNA demonstrated that 9‐hydroxybenzo (a) pyrene was almost six times more effective than benzo (a) pyrene itself. Addition of trichloropropene‐2,3‐oxide to the reaction mixture enhanced the mutagenicity and DNA alkylation by benzo (a) pyrene but had little or no effect on the 9‐hydroxybenzo (a) pyrenemediated mutagenicity and alkylation. On the other hand, 7,8‐benzoflavone inhibited the microsome‐mediated mutagenicity and DNA alkylating activity of both hydrocarbons.