Discovery of anti-inflammatory agents from 3, 4-dihydronaphthalene-1(2H)-one derivatives by inhibiting NLRP3 inflammasome activation.

NLRP3 inflammatory vesicles are a polymer of cellular innate immunity composed of a pair of proteins. The continuous activation of NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammatory vesicles induces the occurrence and enhancement of inflammatory response. In this study, a series of 3, 4-dihydronaphthalene-1(2H)-one derivatives (DHNs, 6a-u, 7a-e, 8a-n) were synthesized and characterized by NMR and HRMS. We evaluated the cytotoxicity and anti-inflammatory activity of all compounds in vitro, and selected 7a substituted by 7-Br in A-ring and 2-pyridylaldehyde in C-ring as effective lead compounds. Specifically, 7a can block the assembly and activation of NLRP3 inflammasome by down-regulating the expression of NLPR3 and apoptosis-associated speck-like protein containing a CARD (ASC), and inhibiting the production of reactive oxygen species (ROS) and other inflammatory mediators. In addition, 7a inhibits the phosphorylation of inhibitor kappa B alpha (IκBα) and NF-κB/p65 and the nuclear translocation of p65, thereby inhibiting nuclear factor kappa-B (NF-κB) signaling. Molecular docking analysis confirmed that 7a could reasonably bind the active sites of NLRP3, ASC and p65 proteins. Therefore, 7a is predicted as a potential NLRP3 inflammatory vesicle inhibitor and deserves further research and development.