1-Butylindoline-2,3-dione derivatives as potent VEGFR-2 inhibitors: synthesis, mechanistic anticancer studies, and molecular dynamics simulations.

A novel series of N-butyl isatin (indolin-2-one) derivatives was designed and synthesized as potential VEGFR-2-targeted anticancer agents, drawing inspiration from the oxindole-based inhibitor sunitinib. The synthesized compounds were assessed for antiproliferative activity against colorectal cancer cell lines (HT29 and HCT116) and for their inhibitory potential on VEGFR-2. Compound 6b exhibited the highest potency, demonstrating strong VEGFR-2 inhibition comparable to that of sunitinib. Mechanistic investigations in HCT116 cells demonstrated that 6b induced G0/G1 cell cycle arrest and promoted apoptosis, which was associated with the upregulation of p53 and Bax, downregulation of Bcl-2, and suppression of Cyclin D1 and Cyclin E expression. Furthermore, 6b markedly decreased VEGF-A expression, supporting modulation of VEGF/VEGFR-2-associated signaling. Molecular docking studies involving VEGFR-2 (PDB ID: 4AGD) demonstrated favorable binding of compound 6b in the ATP-binding pocket, establishing essential interactions with essential residues. Docking validation was established through the successful redocking of sunitinib, yielding an RMSD of 0.44 Å. Additionally, 500 ns molecular dynamics simulations indicated stable backbone behavior, regulated ligand fluctuations, preserved structural compactness, and sustained hydrogen bonding within the 6b-VEGFR-2 complex. The findings collectively identify compound 6b as a promising lead candidate for further development as a VEGFR-2-targeted anticancer agent.