The site of substitution of the methyl group in the bioalkylation of benzo[<i>a</i>]pyrene

Abstract

The major product of the S-adenosyl-L-methionine methyltransferase dependent substitution reaction (bioalkylation) of benzo[a]pyrene in preparations of rat liver cytosol was isolated by solvent extraction and high performance liquid chromatography and its structure determined by GC/MS and NMR. The results indicate that the methyl group is introduced at the center of highest chemical reactivity (or carbon atom at which it is easiest to localize pi electrons) in the anthracene nucleus, giving rise to 6-methylbenzo[a]pyrene. These data, unequivocally demonstrate the site of substitution of the methyl group in the bioalkylation of benzo[a]pyrene.