New (3-(1H-benzo[d]imidazol-2-yl))/(3-(3H-imidazo[4,5-b]pyridin-2-yl))-(1H-indol-5-yl)(3,4,5-trimethoxyphenyl)methanone conjugates as tubulin polymerization inhibitors.

A series of new (3-(1H-benzo[d]imidazol-2-yl))/(3-(3H-imidazo[4,5-b]pyridin-2-yl))-(1H-indol-5-yl)(3,4,5-trimethoxyphenyl)methanone conjugates 4-6(a-i) were synthesized and evaluated for their antiproliferative activity on selected human cancer cell lines such as prostate (DU-145), lung (A549), cervical (HeLa) and breast (MCF-7). Most of these conjugates showed considerable cytotoxicity with IC50 values ranging from 0.54 to 31.86 μM. Among them, compounds 5g and 6f showed significant activity against human prostate cancer cell line DU-145 with IC50 values of 0.68 μM and 0.54 μM, respectively. Tubulin polymerization assay and immunofluorescence analysis results suggest that these compounds effectively inhibit microtubule assembly formation in DU-145. Further, the apoptosis-inducing ability of these derivatives (5g and 6f) was confirmed by Hoechst staining, measurement of mitochondrial membrane potential and ROS generation and annexin V-FITC assays.