1H-benzimidazole-2-yl hydrazones as tubulin-targeting agents: Synthesis, structural characterization, anthelmintic activity and antiproliferative activity against MCF-7 breast carcinoma cells and molecular docking studies.

In the present study, fifteen benzimidazolyl-2-hydrazones 7a-7o of fluoro-, hydroxy- and methoxy-substituted benzaldehydes and 1,3-benzodioxole-5-carbaldehyde were synthesized and their structure was identified by IR, NMR, and elemental analysis. The compounds 7j 2-(3-hydroxybenzylidene)-1-(5(6)-methyl-1H-benzimidazol-2-yl)hydrazone and 7i 2-(3-hydroxybenzylidene)-1-(1H-benzimidazol-2-yl)hydrazone have exerted the strongest anthelmintic activity (100% after 24 h incubation period at 37 °C) against isolated muscle larvae of Trichinella spiralis in an in vitro experiment. The in vitro cytotoxicity assay towards MCF-7 breast cancer cells and mouse embryo fibroblasts 3T3 showed that the studied benzimidazolyl-2-hydrazones exhibit low to moderate cytotoxic effects. The ability of the studied benzimidazolyl-2-hydrazones to modulate microtubule polymerization was confirmed and suggested that their anthelmintic action is mediated through inhibition of the tubulin polymerization likewise the other known benzimidazole anthelmitics. It was also shown that the four most promising benzimidazolyl-2-hydrazones do not affect significantly the AChE activity even at high tested concentration, thus indicating that they do not have the potential for neurotoxic effects. The binding mode of compounds 7j and 7n in the colchicine-binding site of tubulin were clarified by molecular docking simulations. Taken together, these results demonstrate that for the synthesized benzimidazole derivatives the anthelmintic activity against T. spiralis and the inhibition of tubulin polymerization are closely related.