Mutagenic activity of the glutathione S-transferase substrate 1-chloro-2,4-dinitrobenzene (CDNB) in the Salmonella mutagenicity assay

The mutagenicity of the commonly used glutathione S-transferase substrates 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB) was investigated in the Salmonella mutagenicity assay. CDNB induced a concentration-dependent mutagenic response in Salmonella typhimurium strain TA98. Incorporation of an activation system derived from Aroclor 1254-induced rats did not influence mutagenic response. Under the same conditions DCNB failed to display mutagenic activity. The mutagenic activity of CDNB was attenuated in bacterial strains under-expressing nitroreductase or O-acetylase activity but, in contrast, it was exaggerated in an O-acetylase over-expressing strain. It is inferred that CDNB exhibits a mutagenic response following reduction of the nitro-group to the hydroxylamine, which is further acetylated to form the acetoxy derivative that presumably breaks down spontaneously to generate the nitrenium ion, the likely ultimate mutagen. (C) 2002 Elsevier Science B.V. All rights reserved.