Discovery of novel sophocarpine derivatives as potential dual Bcl-2 and Mcl-1 inhibitors: design, synthesis and anti-hepatocellular carcinoma evaluation

Hepatocellular carcinoma (HCC) remains one of the leading causes of cancer-related mortality and disease burden worldwide, and its clinical management continues to face substantial challenges. Sorafenib, a widely used systemic therapy for advanced HCC, frequently develops acquired resistance upon long-term treatment, in part due to the overexpression of anti-apoptotic Bcl-2 Family proteins. Herein, guided by the structural features of Sorafenib, the selective Bcl-2 Inhibitor Venetoclax, and the selective Mcl-1 Inhibitor AZD5991, we designed and synthesized a series of novel Sophocarpine-derived analogues bearing a pyridylethyl moiety via a molecular-hybridization strategy. Molecular docking suggested a favorable binding mode, in which the resulting scaffold could occupy the hydrophobic binding pockets of both Bcl-2 and Mcl-1 and engage key residues through hydrogen-bond interactions. In vitro antiproliferative screening (MTT assay) against three human HCC cell lines (Huh-7, MHCC-97H, and HepG2) showed that most compounds exhibited moderate to good activity. Notably, compound S6 emerged as the most potent analogue, with IC₅₀ values of 9.13 ± 0.29 μM (Huh-7), 6.76 ± 0.06 μM (MHCC-97H), and 15.9 ± 0.98 μM (HepG2). Mechanistic studies demonstrated that S6 markedly suppressed proliferation and migration of MHCC-97H cells, induced G1-phase arrest, and promoted Apoptosis. Western blot analysis revealed that S6 downregulated anti-apoptotic proteins Bcl-2 and Mcl-1, induced mitochondrial membrane potential (ΔΨm) depolarization, and activated the caspase-dependent apoptotic cascade, as evidenced by Caspase-3 activation and PARP1 cleavage. In parallel, a 3D-QSAR (CoMFA) model was constructed to rationalize the structure-activity relationship and to inform further lead optimization. Collectively, these findings identify S6 as a promising Sophocarpine derivative with a putative dual Bcl-2/Mcl-1 targeting profile, with significant anti-HCC activity and potential for preclinical development.

Apoptosis; Bcl-2; Dual-target inhibition; Hepatocellular carcinoma; Mcl-1; Sophocarpine derivatives; Synthesis.