Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2003-2-17
pubmed:abstractText
Compound I, (2-[3-[(2,2-difluoro-2(2-pyridyl)ethyl)amino]-6-methyl-2-oxohydropyrazinyl]-N-[(3-fluoro(2-pyridyl))methyl]acetamide, is a potent competitive inhibitor of thrombin that reacts stoichiometrically with the protease. Compounds of this class possess therapeutic potential as anticoagulation agents. During the metabolic characterization of compound I, evidence was obtained for extensive metabolic activation of the pyrazinone ring system. Following administration of (14)C-labeled I to rats, significant levels of irreversibly bound radioactivity to proteins were detected in rat plasma and liver. LC/MS/MS analysis of metabolites formed in rat and human liver microsomes fortified with glutathione (GSH) revealed the presence of two structurally distinct GSH adducts. It is proposed that the first of these GSH conjugates derives from a two electron oxidation of the 6-methyl-2-oxo-3-aminopyrazinone moiety to afford an electrophilic imine-methide intermediate, while the second is formed by addition of GSH to an epoxide formed by P-450-mediated oxidation of the double bond at the 5-6 position of the pyrazinone ring. The addition of GSH to the proposed epoxide facilitates opening of the pyrazinone ring and a rearrangement to afford a stable, rearranged imidazole-containing metabolite. Elucidation of the metabolic activation pathways of I provides structural guidance for the design of thrombin inhibitors with decreased potential for the generation of chemically reactive intermediates.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0893-228X
pubmed:author
pubmed:issnType
Print
pubmed:volume
16
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
198-207
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed-meshheading:12588191-Administration, Oral, pubmed-meshheading:12588191-Animals, pubmed-meshheading:12588191-Binding, Competitive, pubmed-meshheading:12588191-Biotransformation, pubmed-meshheading:12588191-Carbon Radioisotopes, pubmed-meshheading:12588191-Epoxy Compounds, pubmed-meshheading:12588191-Glutathione, pubmed-meshheading:12588191-Humans, pubmed-meshheading:12588191-Imines, pubmed-meshheading:12588191-Microsomes, Liver, pubmed-meshheading:12588191-NADP, pubmed-meshheading:12588191-Nuclear Magnetic Resonance, Biomolecular, pubmed-meshheading:12588191-Oxidation-Reduction, pubmed-meshheading:12588191-Protease Inhibitors, pubmed-meshheading:12588191-Protein Binding, pubmed-meshheading:12588191-Pyrazines, pubmed-meshheading:12588191-Rats, pubmed-meshheading:12588191-Spectrometry, Mass, Electrospray Ionization, pubmed-meshheading:12588191-Thrombin
pubmed:year
2003
pubmed:articleTitle
Metabolic activation of a pyrazinone-containing thrombin inhibitor. Evidence for novel biotransformation involving pyrazinone ring oxidation, rearrangement, and covalent binding to proteins.
pubmed:affiliation
Department of Drug Metabolism, Merck Research Labs, West Point, Pennsylvania, USA. romi_singh@merck.com
pubmed:publicationType
Journal Article