Exploration of quinoxaline-benzimidazole hybrids as apoptosis-inducing agents and tubulin polymerisation inhibitors

We herein report the design and synthesis of a new class of quinoxaline-benzimidazole hybrids based on the molecular hybridization concept and evaluation of their in vitro cytotoxicity profile against human cancer cell lines, i.e., colorectal, lung, skin, and mouse melanoma cell line. Among all the screened compounds, compound 5l (2-(1-(3, 4-dichlorobenzyl)-1H-benzo[d]imidazol-2-yl)quinoxaline) exhibited potent cytotoxicity against lung cancer cell line (A549) with an IC50 of 4.37 +/- 0.09 mu M with a cytospecificity towards cancer cells. Further, AO/ EB, DAPI, DCFDA, and JC-1 staining techniques confirmed that 5l induced apoptosis in the A549 cell line. In addition, 5l in annexin V-FITC/PI assay induced early apoptosis. The clonogenic assay revealed that 5l inhibited colony formation in a dose-dependent manner. Cell cycle distribution analysis unveiled that 5l caused the arrest of G2/M phase of cell cycle. Moreover, 5l inhibited tubulin polymerization with an IC50 value of < 2.19 <mu>M. Docking studies revealed that 5l has a prominent binding affinity towards colchicine binding site of alpha/beta-tubulin with good protein-ligand interactions with a binding energy of-45.139 kcal/mol. In silico ADME/T prediction studies disclosed the favourable drug-like properties of 5l.