Synthesis and evaluation of the anti-inflammatory activity of novel 8-quinolinesulfonamide derivatives as TLR4/MD-2 inhibitors with efficacy in adjuvant-induced arthritis.

In this study, a series of 8-quinolinesulfonamidederivatives was synthesized, and their anti-inflammatory activity was evaluated. Among them, compound 3l was found to be the best anti-inflammatory agent, with IC50 values of 2.61 ± 0.39, 9.74 ± 0.85, and 12.71 ± 1.34 μM against NO, TNF-α and IL-1β production respectively. And 3l could significantly prevent lipopolysaccharide (LPS)-induced expression of inflammatory mediators (iNOS and COX-2). Molecule docking results showed that 3l could bind to the LPS binding site of toll-like receptor 4 (TLR4)/MD-2, and 3l was then identified as TLR4/MD-2 inhibitor by co-immunoprecipitation (co-IP) and cellular thermal shift assay (CTESA). Preliminary mechanism studies indicated that 3l could prevent TLR4 from being activated by disrupting TLR4/MD-2 heterodimerization and TLR4 homodimerization, thereby blocking the activation of the NF-κB/MAPK signaling pathway. Furthermore, observation of rat foot swelling, joint pathology and serum inflammatory cytokine levels proved that compound 3l had a significant therapeutic effect on adjuvant-induced arthritis (AIA) in rats in vivo. These results indicated that compound 3l is a potential anti-inflammatory agent, from which more effective anti-inflammatory drugs could be developed.