title: Zebularine metabolism by aldehyde oxidase in hepatic cytosol from humans, monkeys, dogs, rats, and mice: influence of sex and inhibitors.
abstract: To aid in the clinical evaluation of zebularine, a potential oral antitumor agent, we initiated studies on the metabolism of zebularine in liver cytosol from humans and other mammals. Metabolism by aldehyde oxidase (AO, EC 1.2.3.1) was the major catabolic route, yielding uridine as the primary metabolite, which was metabolized further to uracil by uridine phosphorylase. The inhibition of zebularine metabolism was studied using raloxifene, a known potent inhibitor of AO, and 5-benzylacyclouridine (BAU), a previously undescribed inhibitor of AO. The Michaelis-Menten kinetics of aldehyde oxidase and its inhibition by raloxifene and BAU were highly variable between species.
authors.affiliation: Laboratory of Clinical Pharmacology, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, USA. klecker@cder.fda.gov
authors.forename: Raymond W
authors.initials: RW
authors.lastname: Klecker
authors.forename: Richard L
authors.initials: RL
authors.lastname: Cysyk
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Collins
mesh_terms: D042931:Aldehyde Oxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003562:Cytidine / Q000031:analogs & derivatives* / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism*; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D000882:Haplorhini; D006801:Humans; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008252:Macaca fascicularis; D008297:Male; D051379:Mice; D051381:Rats
chemical_list: D004791:Enzyme Inhibitors; D003562:Cytidine; C009131:pyrimidin-2-one beta-ribofuranoside; D042931:Aldehyde Oxidase