New benzimidazole derivatives as topoisomerase I inhibitors--synthesis and fluorometric analysis.

A series of new benzimidazole derivatives with potential anticancer activity were tested as a new topoisomerase I inhibitors. The fluorometric method was used to determine in vitro the quantitative level of plasmid DNA relaxation by these compounds. Optimization of the fluorometric system and validation of the established analytical method were performed. Out of benzimidazole derivatives which were analyzed, in the case of five derivatives inhibition of topoisomerase I was greater than camptothecin (compounds 11, 12, 15, 21, 22).