Design, synthesis, molecular docking, and anticancer activity of benzoxazole derivatives as VEGFR-2 inhibitors

Novel series of benzoxazoles 4(a-f)-16 were designed, synthesized, and evaluated for anticancer activity against HepG2, HCT-116, and MCF-7 cells. HCT-116 was the most sensitive cell line to the influence of the new derivatives. In particular, compound 5(e) was found to be the most potent against HepG2, HCT-116, and MCF-7 with IC50 = 4.13 +/- 0.2, 6.93 +/- 0.3, and 8.67 +/- 0.5 mu M, respectively. Compounds 5(c), 5(f), 6(b), 5(d), and 6(c) showed the highest anticancer activities against HepG2 cells with IC50 of 5.93 +/- 0.2, 6.58 +/- 0.4, 8.10 +/- 0.7, 8.75 +/- 0.7, and 9.95 +/- 0.9 mu M, respectively; HCT-116 cells with IC50 of 7.14 +/- 0.4, 9.10 +/- 0.8, 7.91 +/- 0.6, 9.52 +/- 0.5, and 12.48 +/- 1.1 mu M, respectively; and MCF-7 cells with IC50 of 8.93 +/- 0.6, 10.11 +/- 0.9, 12.31 +/- 1.0, 9.95 +/- 0.8, and 15.70 +/- 1.4 mu M, respectively, compared with sorafenib as a reference drug with IC50 of 9.18 +/- 0.6, 5.47 +/- 0.3, and 7.26 +/- 0.3 mu M, respectively. The most active compounds 5(c-f) and 6(b,c) were further evaluated for their vascular endothelial growth factor receptor-2 (VEGFR-2) inhibition. Compounds 5(e) and 5(c) potently inhibited VEGFR-2 at lower IC50 values of 0.07 +/- 0.01 and 0.08 +/- 0.01 mu M, respectively, compared with sorafenib (IC50 = 0.1 +/- 0.02 mu M). Compound 5(f) potently inhibited VEGFR-2 at low IC50 value (0.10 +/- 0.02 mu M) equipotent to sorafenib. Our design was based on the essential pharmacophoric features of the VEGFR-2 inhibitor sorafenib. Molecular docking was performed for all compounds to assess their binding pattern and affinity toward the VEGFR-2 active site.