Design, Synthesis and in Vitro Evaluation of 6-Amide-2-aryl Benzoxazole/benzimidazole Derivatives Against Tumor Cells by Inhibiting VEGFR-2 Kinase.

Herein, we have carried out a structural optimization campaign to discover the novel anti-tumor agents with our previously screened YQY-26 as the hit compound. A library of thirty-seven 6-amide-2-aryl benzoxazole/benzimidazole derivatives has been designed and synthesized based on the highly conserved active site of VEGFR-2. Several title compounds exhibited selective inhibitory activities against VEGFR-2 than EGFR kinases, which also displayed selective anti-proliferation potency against the HUVEC and HepG2 than the A549 and MDA-MB-231 cancer cell lines. The newly synthesized compounds were evaluated for anti-angiogenesis capability by chick chorioallantoic membrane (CAM) assay. Among them, compounds 9d showed the most potent anti-angiogenesis ability (79% inhibition at 10 nM/eggs), the efficient cytotoxic activities (in vitro against the HUVEC and HepG2 cell lines with IC50 values of 1.47 and 2.57 μM, respectively), and excellent VEGFR-2 kinase inhibition (IC50 = 0.051 μM). The molecular docking analysis revealed that compound 9d is a Type II inhibitor of VEGFR-2 kinase. These results indicated that the 6-amide-2-arylbenzoxazole and 6-amide-2-aryl benzimidazole derivatives are promising inhibitors of VEGFR-2 kinase for the potential treatment of anti-angiogenesis.