title: Stereoselective inhibition of inducible cyclooxygenase by chiral nonsteroidal antiinflammatory drugs.
abstract: The stereoselective inhibition of inducible cyclooxygenase (COX-2) by chiral nonsteroidal antiinflammatory drugs (NSAIDs)--ketoprofen, flurbiprofen, and ketorolac--has been investigated. The activity and inhibition of COX-2 was assessed in three different in vitro systems: guinea pig whole blood, lipopolysaccharide (LPS)-stimulated human monocytes, and purified preparations of COX-2 from sheep placenta. The results were compared with the inhibition of constitutive cyclooxygenase (COX-1) in three parallel in vitro models: clotting guinea pig blood, human polymorphonuclear leukocytes, and purified COX-1 from ram seminal vesicles. In the whole blood model, both isoenzymes were inhibited by S-enantiomers with equal potency but S-ketoprofen was the most active on COX-2 (IC50 = 0.024 mumol/L). In contrast, both isoenzymes were inhibited less than 40% by all three R-enantiomers at high concentration (> 1 mumol/L). The inhibition of COX by the R-enantiomers may be attributed to contamination with the S-enantiomers (approximately 0.5%). A significant degree of enantioselectivity in COX-2 inhibition was also observed in intact cells. The S-enantiomers inhibited COX-2 from monocytes with IC50 values in the range of 2 to 25 nmol/L, being 100 to 500-fold more potent than the corresponding R-enantiomers. Finally, S-ketoprofen inhibited COX-2 from sheep placenta (IC50 = 5.3 mumol/L) with slightly less potency than S-ketorolac (IC50 = 0.9 mumol/L) and S-flurbiprofen (IC50 = 0.48 mumol/L), whereas the R-enantiomers were found to be essentially inactive (IC50 > or = 80 mumol/L). It is concluded that the chiral NSAIDs studied here inhibit with comparable stereoselectivity both COX-2 and COX-1 isoenzymes, and that the inhibition of COX-2 previously observed for racemic NSAIDs should be attributed almost exclusively to their S-enantiomers.
authors.affiliation: Research and Development Department, Laboratories Menarini S.A., Badalona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Carabaza
authors.forename: F
authors.initials: F
authors.lastname: Cabré
authors.forename: E
authors.initials: E
authors.lastname: Rotllan
authors.forename: M
authors.initials: M
authors.lastname: Gómez
authors.forename: M
authors.initials: M
authors.lastname: Gutiérrez
authors.forename: M L
authors.initials: ML
authors.lastname: García
authors.forename: D
authors.initials: D
authors.lastname: Mauleón
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D005260:Female; D005480:Flurbiprofen / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D007660:Ketoprofen / Q000494:pharmacology; D020910:Ketorolac; D008297:Male; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012756:Sheep; D013237:Stereoisomerism; D014046:Tolmetin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D005480:Flurbiprofen; D007660:Ketoprofen; D014046:Tolmetin; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D020910:Ketorolac