Mutagenicity of (R) and (S) styrene 7,8-oxide and the intermediary mercapturic acid metabolites formed from styrene 7,8-oxide.

We have tested the two enantiomers of styrene 7,8-oxide and various thioether metabolites of racemic styrene 7,8-oxide for their direct mutagenicity in Salmonella typhimurium TA100. The mutagenicity data suggests that the (R) enantiomer is more mutagenic than the (S) enantiomer, with the racemic mixture intermediate between the two. The thioether metabolites were not mutagenic. The difference in the mutagenicities of enantiomers probably resulted from a stereoselective process in the Salmonella tester strain. At the present time it is not clear whether the rate-limiting reaction is the interaction of the enantiomers with DNA or some other cellular component.