Design and synthesis of 4,5-diphenyl-4-isoxazolines: novel inhibitors of cyclooxygenase-2 with analgesic and antiinflammatory activity.
4,5-Diphenyl-4-isoxazolines (13a-k) possessing a variety of substituents (H, F, MeS, MeSO2) at the para position of one of the phenyl rings were synthesized for evaluation as analgesic and selective cyclooxygenase-2 (COX-2) inhibitory antiinflammatory (AI) agents. Although the 4,5-phenyl-4-isoxazolines (13a-d,f), which do not have a C-3 Me substituent, exhibited potent analgesic and AI activities, those compounds evaluated (13a, 13b, 13h, and 13k) were not selective inhibitors of COX-2. In contrast, 2,3-dimethyl-5-(4-methylsulfonylphenyl)-4-phenyl-4-isoxazoline (13j) exhibited excellent analgesic and AI activities, and it was a potent and selective COX-2 inhibitor (COX-1, IC(50) = 258 microM; COX-2, IC(50) = 0.004 microM). A related compound 13k having a F substituent at the para position of the 4-phenyl ring was also a selective (SI = 3162) but less potent (IC(50) = 0.0316 microM) inhibitor of COX-2 than 13j. A molecular modeling (docking study) for 13j showed that the S atom of the MeSO2 substituent is positioned about 6.46 A inside the entrance to the COX-2 secondary pocket (Val(523)) and that a C-3 Me (13j, 13k) central isoxazoline ring substituent is crucial to selective inhibition of COX-2 for this class of compounds.
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Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2N8, Canada.
Praveen Rao
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Knaus
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D000009:Abdominal Muscles / Q000187:drug effects / Q000502:physiology; D000737:Androstenols / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002351:Carrageenan; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D008565:Membrane Proteins; D008958:Models, Molecular; D009119:Muscle Contraction / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases; D051381:Rats; D013329:Structure-Activity Relationship
D000737:Androstenols; D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; C017039:azastene; D002351:Carrageenan; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat