Mutagenicity of several derivatives of dipyrido[1,2-a:2′,3′-d]imidazoles

Different derivatives of dipyrido[1,2-a:2′,3′-d]imidazoles have been investigated, as mutagens for Salmonella typhimurium. The nature of different substitution groups and their positions on the base ring influenced markedly the mutagenicity of these compounds. From this structure/effect relationship study, it was demonstrated that the 2 and 3 positions were of special interest. The 3-N-hydroxylated compound was the most active mutagen tested. We also observed that the frequently found frameshift mutagens were responsible for base-pair substitution. Metabolic activation by liver S9 mix increased the reversion rates of the strains tested. The SCE assays correlated poorly with the Salmonella/microsome mutagenicity test.