Substituted 2,5′-Bi-1H-benzimidazoles: Topoisoraerase 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.