Hybrid benzylidene thiazolidine-2,4-diones as potent apoptosis-inducing anticancer agents: design-driven optimization, cytotoxic profiling, and mechanistic validation in prostate cancer

The smart combination of fragment merging, bioisosteric replacement, and conformational rigidification allowed for the design of a new series of N-(phenylthiazolyl)acetamide hybrids based on benzylidene-thiazolidine-2,4-dione as possible anticancer leads. Compounds with significantly increased cytotoxic activity were developed by methodically altering the benzylidene C4 ring structure and specifically modifying the thiazole olefinic bond. Analogues HB161 and HB162, which outperformed doxorubicin (DOX) against a variety of cancer types, demonstrated the highest average growth inhibition (GI) among the synthesized derivatives (HB121–HB169). A thorough IC₅₀ analysis showed that HB123 and HB161 were more effective against PC-3 prostate cancer cells (7.14 and 7.90 µM, respectively), whereas HB162 showed balanced activity across colorectal, breast, and prostate cancer models. Strong apoptosis induction was demonstrated by mechanistic investigation, which showed that BAX and Caspase-3/7/9 were significantly upregulated while BCL-2, MMP-2, and MMP-9 were suppressed. Moreover, flow cytometry demonstrated that HB162-induced G0/G1 cell-cycle arrest is a major contributor to its antiproliferative action. To support HB161 and HB162 as BCL-2 downregulators, a molecular docking study was conducted focusing on the BCL-2 receptor, an essential component of the pathway that triggers apoptosis. Positive physicochemical behavior, non-mutagenicity, and good drug-likeness were highlighted by in silico ADMET profiling. In conclusion, this hybrid scaffold offers a promising platform for next-generation anticancer drugs that target apoptosis, especially for the treatment of prostate cancer.