title: A novel family of hydroxamate-based acylating inhibitors of cyclooxygenase.
abstract: Aspirin irreversibly inhibits cyclooxygenase (COX) by acetylating a serine residue in the active site. We synthesized a series of novel acylating agents based on our previously reported acetylating compound, O-acetylsalicylhydroxamic acid. One of these, triacetylsalicylhydroxamic acid (TriAcSHA) was more effective than aspirin and O-acetylsalicylhydroxamic acid in inactivating both COX-1 and COX-2. Preincubation of COX-1 with inhibitor for 5 min yielded IC(50) values of 18 microM for TriAcSHA and 60 microM for acetylsalicylic acid. Inhibition was time-dependent, with complete inhibition within 10 min at a concentration of 50 microM. As with aspirin, mutation of the serine 530 of COX-1 to alanine abolished the activity of the TriAcSHA. Mutation of the alanine 119 to a glutamine markedly reduced the sensitivity to TriAcSHA, suggesting that this residue was necessary for the interaction with the enzyme. TriAcSHA was also more effective than aspirin as an inhibitor of platelet aggregation induced by arachidonic acid. The diacetylated phenylhydroxamates N-methyl-O,O-diacetylsalicylhydroxamic acid, N,O-diacetylbenzohydroxamic acid, and 2-methyl-O,N-diacetylbenzohydroxamic acid showed reduced or absent activity against COX-1. In addition, we synthesized a series of triacylsalicylhydroxamic acids with progressively longer acyl groups (three to six carbons). All of the compounds inhibited COX-1 and demonstrated progressively greater COX-1 selectivity with increasing number of carbons. Hence, salicylhydroxamic acid provides a versatile backbone for the generation of a family of acylating inhibitors of cyclooxygenase.
authors.affiliation: Department of Clinical Pharmacology, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: C M
authors.initials: CM
authors.lastname: Dooley
authors.forename: M
authors.initials: M
authors.lastname: Devocelle
authors.forename: B
authors.initials: B
authors.lastname: McLoughlin
authors.forename: K B
authors.initials: KB
authors.lastname: Nolan
authors.forename: D J
authors.initials: DJ
authors.lastname: Fitzgerald
authors.forename: C T
authors.initials: CT
authors.lastname: Sharkey
mesh_terms: D000107:Acetylation; D000818:Animals; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D019556:COS Cells; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000737:chemistry; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000235:genetics; D008565:Membrane Proteins; D010974:Platelet Aggregation / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics; D012457:Salicylamides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D012694:Serine / Q000235:genetics / Q000378:metabolism
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D006877:Hydroxamic Acids; D007527:Isoenzymes; D008565:Membrane Proteins; D012457:Salicylamides; C471132:triacetylsalicylhydroxamic acid; D012694:Serine; C005703:salicylhydroxamic acid; D001120:Arginine; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases