Metal-free domino amination-Knoevenagel condensation approach to access new coumarins as potent nanomolar inhibitors of VEGFR-2 and EGFR

A metal-free, atom-economy and simple work-up domino amination-Knoevenagel condensation approach to construct new coumarin analogous (4a-f and 8a-e) was described. Further, new formyl (5a,d-f) and nitro (9a,d-f) coumarin derivatives were synthesized via C-N coupling reaction of various cyclic secondary amines and 4-chloro-3-(formyl-/nitro)coumarins (1a,c), respectively. The confirmed compounds were screened for their in vitro anti-proliferative activity against KB-3-1, A549 and PC3 human cancer cell lines using resazurin cellular-based assay. Among them, coumarin derivatives 4e and 8e displayed the best anti-cervical cancer potency (KB-3-1) with IC(50) values of 15.5 ± 3.54 and 21 ± 4.24 μM, respectively. Also, 4e showed the most promising cytotoxicity toward A549 with IC(50) value of 12.94 ± 1.51 μM. As well, 9d presented a more significant impact of potency against PC3 with IC(50) 7.31 ± 0.48 μM. Moreover, 8d manifested selectivity against PC3 (IC(50) = 20.16 ± 0.07 μM), while 8e was selective toward KB-3-1 cell line (IC(50) = 21 ± 4.24 μM). Matching with docking profile, the enzymatic assay divulged that 8e is a dual potent single-digit nanomolar inhibitor of VEGFR-2 and EGFR with IC(50) values of 24.67 nM and 31.6 nM that were almost equipotent to sorafenib (31.08 nM) and erlotinib (26.79 nM), respectively.