Design and synthesis of novel 2-phenyl-5-(1,3-diphenyl-1H-pyrazol-4-yl)-1,3,4-oxadiazoles as selective COX-2 inhibitors with potent anti-inflammatory activity

• Novel 2-phenyl-5-(1,3-diphenyl-1H-pyrazol-4-yl)-1,3,4-oxadiazoles were synthesized.
• Compounds were evaluated for in vitro cyclooxygenase (COX) assay.
• Most potent compounds were evaluated for in vivo anti-inflammatory activity.
• Lead compound 9g was further evaluated for analgesic and ulcerogenic properties.

A novel series of 2-phenyl-5-(1,3-diphenyl-1H-pyrazol-4-yl)-1,3,4-oxadiazoles were designed and synthesized for selective COX-2 inhibition with potent anti-inflammatory activity. Among the compounds tested, 9g (2-(3-(4-nitrophenyl)-1-phenyl-1H-pyrazol-4-yl)-5-phenyl-1,3,4-oxadiazole) was found to be the most potent inhibitor of COX-2 with IC50 of 0.31 μM showing promising degree of anti-inflammatory activity in the carrageenan-induced rat paw edema model with ED50 of 74.3 mg/kg. The lead compound 9g further showed suppression of acetic acid-induced writhes comparable to that of aspirin and gastro-sparing profile superior to the aspirin. Molecular docking analysis displayed higher binding affinity of ligands towards COX-2 than COX-1.

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