Evidence that nitroarene metabolites form mutagenic adducts with DNA-adenine as well as with DNA-guanine.

Nitropyrenes as well as several other nitroarenes and their metabolites exhibit considerable mutagenicity for Salmonella tester strains (TA102 and TA96) which have adenine-thymine base pairs at the mutational target. This finding is unexpected as previous biochemical studies had shown that arylation at the C8 position of DNA-guanine is the only chemically and biologically significant reaction. This conclusion is supported by the extraordinary mutagenic potency of these chemicals in Salmonella strains with guanine at the mutational site (e.g., TA98). The present results indicate that a minor reaction with DNA-adenine may result in the formation of an unusually potent promutagenic DNA adduct.