Design, Synthesis, and Anti-Inflammatory Activity Evaluation of Novel thieno[2,3-d]Pyrimidin-4(3H)-One-Based NLRP3 Inflammasome Inhibitors.

The NLRP3 inflammasome plays a critical role in the pathogenesis of inflammatory diseases and has emerged as a promising therapeutic target. Our preliminary studies revealed that istradefylline, an anti-Parkinsonian agent, exhibits moderate NLRP3 inhibitory activity. Furthermore, we optimized the structure and activity of istradefylline, leading to a series of thienobenzo[d]pyrimidin-4(3H)-one-based NLRP3 inhibitors. Among them, compound L22 exhibited the most potent inhibitory activity (IC50 = 0.16 μM), which was 10-fold stronger than istradefylline (1.81 μM). L22 directly binds to the NLRP3 NACHT domain (KD = 357.8 nM), inhibiting inflammasome assembly and activation. L22 is an orally bioavailable NLRP3 inhibitor, and significantly alleviated symptoms in a DSS-induced ulcerative colitis model. Acute and subacute toxicity studies indicated that L22 possesses a favorable safety profile. These results not only provide compelling evidence for developing more potent NLRP3 inhibitors based on this scaffold but also offer an optimizable lead compound for colitis treatment.