PTC-Assisted Chemoselective S-Alkylation of 5-Mercapto-1,3,4-Oxadiazol Derivative: Multi-Target Anticancer via EGFR, Telomerase, and Thymidylate Synthase Inhibition With Apoptosis Induction.

Multi-target enzyme inhibition represents a promising strategy to overcome resistance and improve therapeutic outcomes in cancer therapy. In this study, a new series of 1,3,4-oxadiazole derivatives was synthesized and evaluated for cytotoxic and multi-target anticancer activities. Several compounds demonstrated potent antiproliferative effects against HepG2, MCF-7, and HCT-116 cancer cell lines with reduced toxicity toward WI-38 normal fibroblasts. Among them, compounds 1, 9, 12, and 13 emerged as the most promising candidates, showing strong cytotoxicity and favorable selectivity profiles. Enzyme inhibition assays confirmed their ability to target key oncogenic enzymes, including wild-type and mutant (T790M) EGFR, telomerase, and thymidylate synthase. Mechanistic studies revealed that compound 12 induced G1 phase cell cycle arrest and promoted apoptosis in HepG2 cells with minimal necrosis. Molecular docking, molecular dynamics simulations, and MM-GBSA analyses supported stable binding of the active compounds within the catalytic sites of the investigated enzymes. Overall, these findings identify compounds 1, 9, 12, and 13 as promising multi-target anticancer leads warranting further optimization and development.