title: Carbon-carbon bond cleavage in activation of the prodrug nabumetone.
abstract: Carbon-carbon bond cleavage reactions are catalyzed by, among others, lanosterol 14-demethylase (CYP51), cholesterol side-chain cleavage enzyme (CYP11), sterol 17β-lyase (CYP17), and aromatase (CYP19). Because of the high substrate specificities of these enzymes and the complex nature of their substrates, these reactions have been difficult to characterize. A CYP1A2-catalyzed carbon-carbon bond cleavage reaction is required for conversion of the prodrug nabumetone to its active form, 6-methoxy-2-naphthylacetic acid (6-MNA). Despite worldwide use of nabumetone as an anti-inflammatory agent, the mechanism of its carbon-carbon bond cleavage reaction remains obscure. With the help of authentic synthetic standards, we report here that the reaction involves 3-hydroxylation, carbon-carbon cleavage to the aldehyde, and oxidation of the aldehyde to the acid, all catalyzed by CYP1A2 or, less effectively, by other P450 enzymes. The data indicate that the carbon-carbon bond cleavage is mediated by the ferric peroxo anion rather than the ferryl species in the P450 catalytic cycle. CYP1A2 also catalyzes O-demethylation and alcohol to ketone transformations of nabumetone and its analogs.
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, California (F.V., H.P., P.R.O.M.); Department of Chemistry, University of Queensland, St. Lucia, Brisbane, Australia (S.N.A.Z., V.L.C., J.J.D.V.); and Department of Biological Sciences, Konkuk University, Seoul, Korea (H.P.).
authors.forename: Fatbardha
authors.initials: F
authors.lastname: Varfaj
authors.forename: Siti N A
authors.initials: SN
authors.lastname: Zulkifli
authors.forename: Hyoung-Goo
authors.initials: HG
authors.lastname: Park
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Challinor
authors.forename: James J
authors.initials: JJ
authors.lastname: De Voss
authors.forename: Paul R
authors.initials: PR
authors.lastname: Ortiz de Montellano
mesh_terms: D055162:Biocatalysis; D001711:Biotransformation; D002074:Butanones / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D052246:Cyclooxygenase 2 Inhibitors / Q000378:metabolism*; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism; D000077430:Nabumetone; D009280:Naphthaleneacetic Acids / Q000378:metabolism*; D010084:Oxidation-Reduction; D011355:Prodrugs / Q000378:metabolism*; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D002074:Butanones; D052246:Cyclooxygenase 2 Inhibitors; D009280:Naphthaleneacetic Acids; D011355:Prodrugs; C044612:6-methoxy-2-naphthylacetic acid; C504573:CYP1A2 protein, human; D019388:Cytochrome P-450 CYP1A2; D000077430:Nabumetone