title: In vitro metabolism of the anti-androgenic fungicide vinclozolin by rat liver microsomes.
abstract: Vinclozolin (V) is a fungicide used in agricultural settings. V administered to rats is hydrolyzed to 2-[[(3,5-dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid (M1) and 3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide (M2). V, M1 and M2 have antiandrogenic properties by interacting with the androgen receptor. Data on V, M1 and M2 biotransformation are limited. Our objective was to characterize V metabolism by rat liver microsomes. V was incubated with non-treated adult male Long-Evans rat liver microsomes and NADPH. Several metabolites were detected following the extraction of incubate with acetonitrile and analysis by HPLC/DAD/MSD. One metabolite was identified as [3-(3,5-dichlorophenyl)-5-methyl-5-(1,2-dihydroxyethyl)-1,3-oxazolidine-2,4-dione] (M4), which was gradually converted to 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutylanilide (M5). Both co-eluted in the same HPLC peak. Another metabolite ([M7]) was detected by UV but was unstable for mass spectral analysis. The K(M app) for co-eluted M4/M5 and [M7] was 53.7 and 135.4 μM, the V(max app) was 0.812 and 0.669 nmoles/min/mg protein, and CL(int) was 15.1 and 4.9 ml/min/g protein, respectively. Pilocarpine, orphenadrine and proadifen and anti-rat cytochrome P450 (CYP)2A, 2B and 3A antibodies inhibited M4/M5 and [M7] formation. These results indicate that V is efficiently metabolized by CYP. Determination of the metabolites of V will provide further insight into the relationship between toxicity and tissue dose of V and its metabolites.
authors: Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA. asierra@cinvestav.mx
authors: Adolfo
authors: A
authors: Sierra-Santoyo
authors: Esperanza
authors: E
authors: Angeles-Soto
authors: Ma
authors: M
authors: de Lourdes López-González
authors: Randy A
authors: RA
authors: Harrison
authors: Michael F
authors: MF
authors: Hughes
mesh_terms: D000726:Androgen Antagonists / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005659:Fungicides, Industrial / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010080:Oxazoles / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000726:Androgen Antagonists; D005659:Fungicides, Industrial; D010080:Oxazoles; C025643:vinclozolin