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2049076 
Journal Article 
Vinclozolin In Vitro Metabolism By Rat Liver Microsomes 
Sierra-Santoyo, A; Harrison, R; Edwards, B; Barton, HA; Hughes, MF 
2005 
1 
Toxicological Sciences
ISSN: 1096-6080
EISSN: 1096-0929 
TOX/5001702 
84 
1-S 
320 
eng 
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 antiandronegic properties by interacting with the androgen receptor. Data on V, M1 and M2 biotransformation is limited. Our objective was to study the in vitro metabolism of V by rat liver microsomes. V (12.5-200 µM) was incubated in 0.1 M phosphate buffer pH 7.4, 5 mM MgCl2, non-treated adult male Long-Evans rat liver microsomes (1-2 mg) and 1 mM NADPH for 30 min at 37°C. V metabolites from incubation media were extracted in acetonitrile and analyzed by HPLC/DAD/MS. Three metabolites were detected from rat liver metabolism. On the basis of their tret, UV/Vis spectrum and negative ESI mass spectra, two metabolites were identified as 3’, 5’-dichloro-2, 3, 4-trihydroxy-2-methylbutylanilide (M4) ([M-H]- at m/z 293) and N-(2, 3, 4-trihydroxy-2-methyl-1-oxo)-3, 5- dichlorophenyl-1-carbamic acid (M5) ([M-R]- at m/z 246). Based on UV/Vis spectrum alone, a third unidentified metabolite (M6) co-eluted with M4. The KM for co-eluted M4/M6 was 53.6 µM and the Vmax was 0.810 nmoles/min/mg protein. The KM for M5 was 142.3 µM and the Vmax was 0.700 nmoles/min/mg protein. Extracting at a lower pH altered the KM and Vmax values for the 3 metabolites indicating the recovery of V metabolites is pH dependent. These results indicate that V is efficiently metabolized by rats liver microsomes. Determination of the metabolites of V will provide further insight into the relationship between toxicity and tissue dose of V and its metabolites. 
Rats; Animals; Microsomes, Liver/ METABOLISM; Oxazoles/ METABOLISM/PHARMACOKINETICS; In Vitro; Spectrometry, Mass, Electrospray Ionization; Biotransformation; Spectrophotometry, Ultraviolet; Chromatography, High Pressure Liquid; Rats, Long-Evans; Hydrogen-Ion Concentration