Design, Synthesis, and Mechanistic Studies of 5‐Substituted 2‐Oxindoles as Anticancer Agents

In the present study, a series of oxindole‐based compounds modified at the 1 st and 3 rd positions were designed, synthesized, and structurally characterized using spectral techniques. Eighteen synthesized compounds were evaluated for anticancer activity against four cancer cell lines: A549, MCF‐7, MDA‐MB‐231, and HCT116 using the MTT assay. MCF‐7 showed the highest sensitivity, specially four compounds, namely, 4i , 4j , 4p , and 4q displayed significant activity (IC 50 <40 µM). A549 was found to be resistant, while MDA‐MB‐231 and HCT116 showed weak‐to‐moderate responses. All four compounds were evaluated for toxicity studies against noncancerous cell lines T293 and WI‐38, in which 4i and 4p demonstrated favorable safety profiles; especially 4i displayed selectivity indices>10 against both cell lines. Enzyme inhibition assays demonstrated 4i as aEGFR (IC 50 = 22.38 µM) and HER2 (IC 50 = 44.86 µM) inhibitor, superior to 4p . In the molecular docking studies, four most active compounds ( 4i , 4j , 4p , and 4q ) revealed key polar interactions with Ser720, Thr790, and Thr854 of EGFR and fit into the hydrophobic pocket of EGFR; notably, 4i formed an additional π‐cation bond, enhancing stability. MD simulations of 4i ‐EGFR complex showed initial fluctuations (0–20 ns) followed by stabilization up to 60 ns.