New benzoxazole derivatives as potential VEGFR-2 inhibitors and apoptosis inducers: design, synthesis, anti-proliferative evaluation, flowcytometric analysis, and <i>in silico</i> studies

A new series of benzoxazole derivatives were designed and synthesised to have the main essential pharmacophoric features of VEGFR-2 inhibitors. Cytotoxic activities were evaluated for all derivatives against two human cancer cell lines, MCF-7 and HepG2. Also, the effect of the most cytotoxic derivatives on VEGFR-2 protein concentration was assessed by ELISA. Compounds <b>14o</b>, <b>14l</b>, and <b>14b</b> showed the highest activities with VEGFR-2 protein concentrations of 586.3, 636.2, and 705.7 pg/ml, respectively. Additionally, the anti-angiogenic property of compound <b>14b</b> against human umbilical vascular endothelial cell (HUVEC) was performed using a wound healing migration assay. Compound <b>14b</b> reduced proliferation and migratory potential of HUVEC cells. Furthermore, compound <b>14b</b> was subjected to further biological investigations including cell cycle and apoptosis analyses. Compound <b>14b</b> arrested the HepG2 cell growth at the Pre-G1 phase and induced apoptosis by 16.52%, compared to 0.67% in the control (HepG2) cells. The effect of apoptosis was buttressed by a 4.8-fold increase in caspase-3 level compared to the control cells. Besides, different <i>in silico</i> docking studies were also performed to get better insights into the possible binding mode of the target compounds with VEGFR-2 active sites.