A Novel Family of Hydroxamate-Based Acylating Inhibitors of Cyclooxygenase
- Departments of 1Clinical Pharmacology (C.M.D., B.M.L., D.J.F., C.T.S.) and 2Chemistry (M.D., K.B.N.), Royal College of Surgeons in Ireland, Dublin, Ireland
- Desmond Fitzgerald, Dept. of Clinical Pharmacology, Royal College of Surgeons in Ireland, 123 St. Stephens Green, Dublin 2, Ireland. E-mail dfitzgerald{at}rcsi.ie
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 IC50 values of 18 μM for TriAcSHA and 60 μM for acetylsalicylic acid. Inhibition was time-dependent, with complete inhibition within 10 min at a concentration of 50 μM. 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 phenylhydroxamatesN-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.
Footnotes
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Financial support was provided by the Health Research Board, The Research Committee of the Royal College of Surgeons, Enterprise Ireland, and Higher Education Authority of Ireland.
- Abbreviations:
- COX
- cyclooxygenase
- NSAID
- nonsteroidal anti-inflammatory drug
- ASA
- acetylsalicylic acid (aspirin)
- SHA
- salicylhydroxamic acid
- AcSHA
- acetylsalicylhydroxamic acid
- TriAcSHA
- triacetylsalicylhydroxamic acid
- TMPD
- N,N,N′,N′-tetramethyl-p-phenylenediamine dihydrochloride
- DMSO
- dimethyl sulfoxide
- PG
- prostaglandin
- O,O-DiAcSHA
- O,O-diacetylsalicylhydroxamic acid
- N,O-DiAcBHA
- N,O-diacetylbenzohydroxamic acid
- N,O-DiAcSHA
- diacetylsalicylhydroxamic acid
- 2-OMe-N,O-DiAcBHA
- 2-methoxy-N,O-diacetylbenzohydroxamic acid
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- Received July 17, 2002.
- Accepted November 6, 2002.
- The American Society for Pharmacology and Experimental Therapeutics
