title: CYP1A1 and CYP1B1-mediated biotransformation of the antitrypanosomal methamidoxime prodrug DB844 forms novel metabolites through intramolecular rearrangement.
abstract: DB844 (CPD-594-12), N-methoxy-6-{5-[4-(N-methoxyamidino)phenyl]-furan-2-yl}-nicotinamidine, is an oral prodrug that has shown promising efficacy in both mouse and monkey models of second stage human African trypanosomiasis. However, gastrointestinal (GI) toxicity was observed with high doses in a vervet monkey safety study. In the current study, we compared the metabolism of DB844 by hepatic and extrahepatic cytochrome P450s to determine whether differences in metabolite formation underlie the observed GI toxicity. DB844 undergoes sequential O-demethylation and N-dehydroxylation in the liver to form the active compound DB820 (CPD-593-12). However, extrahepatic CYP1A1 and CYP1B1 produced two new metabolites, MX and MY. Accurate mass and collision-induced dissociation mass spectrometry analyses of the metabolites supported proposed structures of MX and MY. In addition, MY was confirmed with a synthetic standard and detection of nitric oxide (NO) release when DB844 was incubated with CYP1A1. Taken altogether, we propose that MX is formed by insertion of oxygen into the amidine CN to form an oxaziridine, which is followed by intramolecular rearrangement of the adjacent O-methyl group and subsequent release of NO. The resulting imine ester, MX, is further hydrolyzed to form MY. These findings may contribute to furthering the understanding of toxicities associated with benzamidoxime- and benzmethamidoxime-containing molecules.
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, Kansas.
authors.forename: Wujian
authors.initials: W
authors.lastname: Ju
authors.forename: Sihyung
authors.initials: S
authors.lastname: Yang
authors.forename: John H
authors.initials: JH
authors.lastname: Ansede
authors.forename: Chad E
authors.initials: CE
authors.lastname: Stephens
authors.forename: Arlene S
authors.initials: AS
authors.lastname: Bridges
authors.forename: Robert D
authors.initials: RD
authors.lastname: Voyksner
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Ismail
authors.forename: David W
authors.initials: DW
authors.lastname: Boykin
authors.forename: Richard R
authors.initials: RR
authors.lastname: Tidwell
authors.forename: James Edwin
authors.initials: JE
authors.lastname: Hall
authors.forename: Michael Zhuo
authors.initials: MZ
authors.lastname: Wang
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001550:Benzamidines / Q000378:metabolism*; D001711:Biotransformation / Q000502:physiology*; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism*; D065633:Cytochrome P-450 CYP1B1; D005663:Furans / Q000378:metabolism*; D000882:Haplorhini / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008862:Microsomes, Liver; D011355:Prodrugs / Q000378:metabolism*
chemical_list: C504229:6-(5-(4-amidinophenyl)furan-2-yl)nicotinamidine; D001550:Benzamidines; D005663:Furans; C504230:N-methoxy-6-(5-(4-(N-methoxyamidino)phenyl)furan-2-yl)nicotinamidine; D011355:Prodrugs; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; C585498:Cyp1b1 protein, mouse; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1
keywords: CYP1A1; CYP1B1; cytochrome P450; drug metabolism; human African trypanosomiasis; intramolecular rearrangement; nitric oxide; prodrugs