Structural modification based on the diclofenac scaffold: Achieving reduced colitis side effects through COX-2/NLRP3 selective inhibition

COX-2/NLPR3-targeted therapy might be beneficial for the inflammation diseases. To discover novel anti-inflammatory compounds with favorable safety profiles, three new series of non-carboxylic diclofenac analogues bearing various ring systems, such as oxadiazoles 4a - 4w , triazoles 6a - 6m , and cyclic imides 7a and 7b , were synthesized. The synthesized analogues were evaluated for their inhibitory activity against COX-2 enzyme. Among them, compound 6k exhibited potent selective COX-2 inhibition (IC 50  = 1.53 μM; selectivity ((IC 50 (COX-1)/IC 50 (COX-2) = 17.19). Treatment with compound 6k effectively suppressed the NF-κB/NLRP3 signaling pathway, resulting in reduced expression of pro-inflammatory factors. The in vivo ulcerative colitis assay demonstrated that compound 6k significantly ameliorated histological damages and showed strong protection against DSS-induced acute colitis. The collected results indicated that compound 6k displays anti-inflammatory activity through COX-2/NLRP3 inhibition. Therefore, compound 6k represents a promising candidate for further development as a new lead compound with reduced colitis side effects.