Genotoxicity of quinoxaline 1,4-dioxide derivatives in Escherichia coli and Salmonella typhimurium.

The mutagenicities of 5 quinoxaline 1,4-dioxide (QdO) derivatives were tested by 2 bacterial assays using forward mutation with Escherichia coli WP2uvrA/pKM101 and reverse mutation with Salmonella typhimurium TA100 and TA98. Potent mutagenic activities of all QdOs tested were observed in both mutation assays. Mutagenicities of these compounds were varied by addition of S9 mix. Their SOS-inducing activities were examined with a 'Rec-lac test' that has been newly developed by us for detecting genotoxins. A high level of SOS-inducing activity was observed in all samples tested. These results suggest that the mutagenicity of QdOs results from the error-prone repair involved in SOS responses.