Design, synthesis, cyclooxygenase inhibition and biological evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives possessing amino/methanesulfonyl pharmacophore.

A new series of 1,3,5-triaryl-4,5-dihydro-1H-pyrazole 10a-l was designed and synthesized via cyclization of chalcones 8a-f with 4-amino/methanesulfonylphenylhydrazine hydrochloride 9a-b. All the synthesized compounds were evaluated for their cyclooxygenase (COX) inhibition, anti-inflammatory activity, ulcerogenic liability and analgesic activity. All compounds were more COX-2 inhibitors than COX-1. While most compounds showed good anti-inflammatory activity, the trimethoxy derivatives (10a, 10b, 10g and 10h) were the most potent derivatives (ED ₅₀ =55.78, 53.99, 67.65 and 69.20μmol/kg respectively) in comparison with celecoxib (ED ₅₀ =82.15μmol/kg). Compounds 10a, 10b, 10g and 10h (ulcer index=2.68, 1.20, 2.63 and 2.66 respectively) showed less ulceration effect than celecoxib (ulcer index=2.90). Also, Compounds 10a, 10b, 10g and 10h showed analgesic activity higher than celecoxib and comparable to that of ibuprofen. In addition, molecular docking studies were performed for compounds 10a, 10b, 10g and 10h and the results were in agreement with that obtained from the in vitro COX inhibition assays.
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