Synthesis, and biological evaluation of 3,6-diaryl-[1,2,4]triazolo[4,3-a]pyridine analogues as new potent tubulin polymerization inhibitors.

On the basis of our previous work, twenty-nine novel [1,2,4]triazolo[4,3-a]pyridines possessing 3,4,5-trimethoxylphenyl groups were designed, synthesized, and evaluated as tubulin polymerization inhibitors. The bioassay results revealed that some of the compounds displayed excellent antiproliferative efficacies in the nanomolar range against HeLa cells, and the most promising derivative 7i demonstrated almost comparable activity to that of the reference CA-4 and sixty-two fold more potent than the parent compound 6 with an IC50 value of 12 nM. Importantly, 7i exhibited high selectivity over the normal human embryonic kidney HEK-293 cells (IC50 > 100 μM). Further mechanism studies revealed that 7i significantly arrested cell cycle at G2/M phase, induced apoptosis with a dose-dependent manner, and disrupted microtubule networks. Additionally, the most active compound 7i effectively inhibited tubulin polymerization with a value similar to that of CA-4 (3.4 and 4.2 μM, respectively). Furthermore, molecular docking analysis suggested that 7i well occupied the colchicine binding pocket of tubulin. The present study highlights that compound 7i is a novel potential tubulin polymerization inhibitor and deserves further investigation for the treatment of cancers.