A novel series of quinoline derivatives of combretastatin A-4 incorporating rigid hydrazone and a cyclic oxadiazole linkers were synthesized and have demonstrated potent tubulin polymerization inhibitory properties. Many of these novel derivatives have shown significant antiproliferative activities in the submicromolar range. The most potent compound, 19h, demonstrated superior IC50 values ranging from 0.02 to 0.04 µM against four cancer cell lines while maintaining low cytotoxicity in MCF-10A non-cancer cells, thereby suggesting 19h’s selectivity towards proliferating cancer cells. In addition to tubulin polymerization inhibition, 19h caused cell cycle arrest in MCF-7 cells at the G2/M phase and induced apoptosis. Collectively, these findings indicate that 19h holds potential for further investigation as a potent chemotherapeutic agent targeting tubulin.

A new series of quinoline derivatives of combretastatin A-4 have been designed, synthesised and demonstrated as tubulin polymerisation inhibitors. These novel compounds showed significant antiproliferative activities, among them, 12c exhibited the most potent inhibitory activity against different cancer cell lines (MCF-7, HL-60, HCT-116 and HeLa) with IC 50 ranging from 0.010 to 0.042 mM, and with selectivity profile against MCF-10A non-cancer cells. Further mechanistic studies suggest that 12c can inhibit tubulin polymerisation and cell migration, leading to G 2 /M phase arrest. Besides, 12c induces apoptosis via a mitochondrial-dependant apoptosis pathway and caused reactive oxygen stress generation in MCF-7 cells. These results provide guidance for further rational development of potent tubulin polymerisation inhibitors for the treatment of cancer. HIGHLIGHTS A novel series of quinoline derivatives of combretastatin A-4 have been designed and synthesised. Compound 12c showed significant antiproliferative activities against different cancer cell lines. Compound 12c effectively inhibited tubulin polymerisation and competed with [ 3 H] colchicine in binding to tubulin. Compound 12c arrested the cell cycle at G 2 /M phase, effectively inducing apoptosis and inhibition of cell migration.

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