Synthesis of novel imino-coumarin and acrylonitrile 2-benzazole hybrids as potent anticancer agents targeting tubulin.

Building on previous research indicating the robust biological effects of coumarins, we focused on exploring imino-coumarin 2-benzazole conjugates. Compounds were tested for antiproliferative activity in vitro, with the most active ones further examined to determine the mechanism of biological action. Five derivatives exhibited significant antiproliferative activity against all tested cancer cells (IC ranging from 0.04 to 8.5 μM), falling within the low micromolar/submicromolar range of inhibitory concentrations. Three compounds had remarkable antiproliferative effects against Capan-1 (IC 0.04-0.05 μM) and DND-41 (IC 0.06-0.07 μM). Promising compounds were further investigated, confirming their mechanism of action through tubulin polymerization inhibition. Computational docking and molecular dynamics simulations confirmed the high affinity of potent derivatives for the tubulin colchicine site and justified the suitability of the employed skeleton by identifying crucial protein-ligand interactions promoting binding. This insight highlights a strategy for further potency improvements through substituents that can donate hydrogen bonds or bear a positive charge, allowing such ligands to more optimally adapt to the identified anionic binding site environment.