title: The 2'-Trifluoromethyl Analogue of Indomethacin Is a Potent and Selective COX-2 Inhibitor.
abstract: Indomethacin is a potent, time-dependent, nonselective inhibitor of the cyclooxygenase enzymes (COX-1 and COX-2). Deletion of the 2'-methyl group of indomethacin produces a weak, reversible COX inhibitor, leading us to explore functionality at that position. Here, we report that substitution of the 2'-methyl group of indomethacin with trifluoromethyl produces CF3-indomethacin, a tight-binding inhibitor with kinetic properties similar to those of indomethacin and unexpected COX-2 selectivity (IC50mCOX-2 = 267 nM; IC50oCOX-1 > 100 μM). Studies with site-directed mutants reveal that COX-2 selectivity results from insertion of the CF3group into a small hydrophobic pocket formed by Ala-527, Val-349, Ser-530, and Leu-531 and projection of the methoxy group toward a side pocket bordered by Val-523. CF3-indomethacin inhibited COX-2 activity in human head and neck squamous cell carcinoma cells and exhibited in vivo anti-inflammatory activity in the carrageenan-induced rat paw edema model with similar potency to that of indomethacin.
authors.affiliation: The A. B. Hancock Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, Center in Molecular Toxicology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville, Tennessee 37232, United States.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Blobaum
authors.forename: Md Jashim
authors.initials: MJ
authors.lastname: Uddin
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Felts
authors.forename: Brenda C
authors.initials: BC
authors.lastname: Crews
authors.forename: Carol A
authors.initials: CA
authors.lastname: Rouzer
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Marnett
keywords: Cyclooxygenase; arachidonic acid; coxib; inflammation; nonsteroidal anti-inflammatory drug; prostaglandin