Substituted 2,5'-Bi-1H-benzimidazoles: topoisomerase I inhibition and cytotoxicity

Several 2'-aryl-5-substituted-2,5'bi-1H-benzimidazole derivatives were synthesized and evaluated as Topoisomerase I poisons and for their cytotoxicity toward the human lymphoblast cell line RPMI 8402. This study focused on 18 2,5'-bi-1H-benzimidazole derivatives which contained either a 5-cyano, a 5-(aminocarbonyl), or a 5-(4-methylpiperazinyl) group. Among these bibenzimidazoles, the pharmacological activity of 2'-phenyl derivatives and the influence of the different positional isomers of either a 2'-tolyl group or a 2'-naphthyl moiety on cytotoxicity and Topoisomerase I inhibitory activity were determined.