Pyrazolone Compounds as Promising Anticancer Agents for Colorectal Cancer: Synthesis, Antiproliferative Activity, and Mechanistic Insights.

Colorectal cancer (CRC) remains a major global health challenge, with current therapeutic options often limited by drug resistance and adverse effects. Small molecules provide distinct advantages, including oral bioavailability, cost-effectiveness, and the ability to target intracellular pathways critical for tumor progression. In this study, we designed and synthesized a new series of pyrazolone derivatives with varied substitution patterns using microwave-assisted methods and evaluated their antiproliferative activity against CRC cell lines (HCT-116 and WiDr). Among these, PL-13 emerged as a potent and selective candidate, exhibiting strong cytotoxicity toward cancer cells while sparing noncancerous CRL-1459 colon cells. Functional assays, including colony formation and wound healing, confirmed its ability to inhibit cell proliferation and migration. Western blot analyses demonstrated that PL-13 induces apoptosis via the intrinsic mitochondrial pathway, as evidenced by increased levels of cleaved caspase-9 and PARP, and modulates LC3A/B expression, suggesting involvement of autophagy. Kinome profiling revealed selective binding of PL-13 to FLT3, which was validated by an IC50 value of 8.2 μM. Molecular docking further supported these findings, showing favorable binding energy (-7.98 kcal/mol) compared to regorafenib (-7.13 kcal/mol). Collectively, these results highlight PL-13 as a promising lead compound for further optimization toward CRC therapy.