Design, synthesis, biological evaluation of novel piperidine-based derivatives as potent poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors

Poly(ADP-ribose) polymerase-1 (PARP-1) is a crucial member of DNA repair enzymes responsible for repairing DNA single-strand breaks. Developing PARP inhibitors based on synthetic lethality strategies is an effective approach for treating breast cancer and other diseases. In this study, a series of novel piperidine-based benzamide derivatives were designed and synthesized using structure-based drug design principles. The anticancer activities of these compounds were evaluated against five human cancer cell lines (MDA-MB-436, CAPAN-1, SW-620, HepG2, SKOV3, and PC3) and the preliminary structure-activity relationships were delineated. Among the compounds, 6a and 15d demonstrated potent antiproliferative effects against MDA-MB-436 cells with IC₅₀ values of 8.56 ± 1.07 μM and 6.99 ± 2.62 μM, respectively. Furthermore, both compounds exhibited excellent inhibitory activity against PARP-1, with IC₅₀ values of 8.33 nM and 12.02 nM, respectively. Mechanistic investigations revealed that 6a and 15d effectively inhibited colony formation and cell migration of HCT116 cells. Moreover, they induced apoptosis by upregulating the expression of Bax and cleaved Caspase-3, while downregulating the expression of Caspase-3 and Bcl-2 in HCT116 cells. Based on its impressive pharmacodynamic data in vitro, we conducted a study to evaluate the efficacy of 15d in a xenograft tumor model in mice when used in combination with cytotoxic agents. Collectively, these findings suggest that 15d could be promising drug candidates worthy of further investigation.