Synthesis of cis-stilbene-based 1,2,4-triazole/1,3,4-oxadiazole conjugates as potential cytotoxic and tubulin polymerization inhibitors

Abstract

In modern medicinal chemistry, a molecular hybridization approach has enabled the design and development of new molecular entities of varied biological interest. Taking this strategy into consideration, a new class of cis-stilbene-based 1,2,4-triazole/1,3,4-oxadiazole conjugates were designed and synthesized. The in vitro cytotoxicity profile of these conjugates was studied on selected human cancer cell lines, namely, MCF-7, A549, MDA-MB-28, SK-Mel-28 and HCT-116. Amongst all, cis-stilbene-based 1,2,4-triazole conjugate 5a emerged as the most promising molecule with an IC₅₀ value of 9.56 ± 0.04 μM toward the A549 (lung cancer) cell line. Additionally, 5a proved to be effective in cell growth inhibition against other cancer cell lines at a concentration ranging from 9.56 to 24.27 μM. Further, mechanistic analysis unveiled apoptosis induction, DNA damage, nuclear morphological changes and ROS generation, as indicated by AO/EtBr, DAPI and DCFDA assays. The induction of early or late apoptosis study was further affirmed via an Annexin FITC-V and PI binding assay by flow cytometry. The cell-cycle distribution analysis by 5a exhibited G2/M phase arrest of cell cycle and tubulin polymerization inhibition at an IC₅₀ value of 12.99 ± 0.50 μM, thereby implying its involvement in microtubule disruption and its potential as an anti-mitotic agent. Interestingly, 5a exhibited the same result pattern as observed with the standard drug colchicine. The results indicated that 5a is safe and non-toxic for the normal cell line HaCaT with an IC₅₀ value of 85.99 ± 0.02 μM. In addition, the detailed binding interaction of 5a with tubulin was also investigated by molecular docking studies. Altogether, the results indicated the role of cis-stilbene-based 1,2,4-triazole/1,3,4-oxadiazole conjugates as a new class of tubulin polymerization inhibitors with significant anti-cancer activities.