Design, synthesis and biological evaluation of novel isoalantolactone-benzylamine derivatives leading to the discovery of a PARP1 inhibitor with selective cytotoxicity against MCF-7 breast cancer cells.

Despite significant advances in cancer treatment in recent years, existing therapies still exhibit notable limitations. Consequently, the continuous development of novel anticancer agents remains paramount. Natural products remain the major source for discovering highly effective and low-toxicity anticancer drug leads. Isoalantolactone, a natural product, demonstrates diverse pharmacological activities, including anti-inflammatory and anticancer effects, but suffers from drawbacks such as poor water solubility, necessitating structural modifications. The enzyme Poly (ADP-ribose) polymerase 1 (PARP1) is a key therapeutic target in breast cancer and its inhibition represents a vital advancement in cancer treatment. In this study, in silico molecular docking was employed to identify binding sites between isoalantolactone and the PARP1 protein. Subsequently, thirty-four of isoalantolactone-benzylamine derivatives were synthesized. Among them, compound ‌ 3-(((3,4,5-trimethoxybenzyl)amino) methyl)-3-demethylene isoalantolactone (3f) exhibited potent inhibitory activity against MCF-7 cells (IC50 = 3.67 μM), which represented a ∼ 7-fold improvement over isoalantolactone itself and demonstrated markedly enhanced solubility. And, MCF-7 cancer cells take up 3 f from the culture environment much more efficiently than L-02 normal cells. The molecular docking results showed that 3 f binds to PARP1 through multiple interactions, exhibiting significantly more interaction bonds than isoalantolactone, and ELISA assays confirmed that 3 f potently inhibits intracellular PARP1 of MCF-7 cancer cells. Moreover, 3 f suppresses the enzymatic function of PARP1 and inhibits the PARP1-mediated DNA damage repair pathway by elevating γH2AX expression levels. In vitro, compound 3 f exhibited significant dose-dependent anti-cancer activity, inhibiting MCF-7 cancer cell migration, invasion, COL1 protein expression and colony formation. It also significantly elevated intracellular reactive oxygen species (ROS) levels in MCF-7 cancer cells. Additionally, 3 f markedly decreased the mitochondrial membrane potential of MCF-7 cells, which may have led to their apoptosis and death. These findings suggest that 3 f acts as a novel PARP1 inhibitor and holds considerable promise for future breast cancer therapy.