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METABOLISM OF VINCLOZOLIN AND ITS METABOLITES IN RATS
Citation:
SierraSantoyo, A., R A. Harrison, H A. Barton, AND M F. Hughes. METABOLISM OF VINCLOZOLIN AND ITS METABOLITES IN RATS. Presented at Society of Toxicology, Baltimore, MD, March 21-25, 2004.
Description:
ETD-04-008
METABOLISM OF VINCLOZOLIN AND ITS METABOLITES IN RAT. A Sierra-Santoyo1, R Harrison2, H A Barton2 and M F Hughes2. 1Toxicology Section, CINVESTAV-IPN, Mexico City, Mexico; 2USEPA, ORD, NHEERL, RTP, NC.
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), 3'5'-dichloro-2-hydroxy-2-methylbut-3-enanilide (M2), and 3,5-dichloroaniline (M3). V, M1 and M2 have antiandrogenic properties by interacting with the androgen receptor. However, data on disposition of V, M1 and M2 is limited. Our objective was to study the metabolism of V, M1 and M2 in vitro and in vivo. Non-treated adult male Long-Evans rat liver microsomes (2 mg) were incubated (30 min, 37oC) in 0.1 M phosphate buffer (PB) pH 7.4, 5 mM MgCl2, 2 mM NADPH with V (50 ?M), M2 or M1 (200 ?M). Rats were administered a single po dose of V (100 mg/Kg) in corn oil. Animals were sacrificed (24 h) and serum and liver were removed and analyzed for V and metabolites. Metabolites from enzyme reactions and serum and liver were extracted in acetonitrile after dilution of samples in PB pH 3.3 (1:4) and analyzed by HPLC/DAD/MS. M1 and M2 formation was evident from V chemical hydrolysis. Another product was observed from V and M2 in vitro metabolism. This metabolite, in both cases had the same tret and using UV/Vis spectrum and negative ESI mass spectra ([M]- at m/z 294 and [M-H]- at m/z 293) was identified as 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutylanilide (M4). M3 was detected only from M2 but its formation was not NADPH-dependent. No metabolites from M1 were detected. Analysis of serum and liver extracts of treated rats showed the presence of M4, M1 and V. M4 levels were at least 5- and 9-fold higher in serum and liver, respectively, than M1 or V. These results indicate that metabolism of V is both enzymatic and non-enzymatic. M4 is an abundant metabolite of V, and may be used as an exposure biomarker for pharmacokinetic modeling of V. These results may clarify the relationship between toxicity and tissue dose of V and its metabolites. (Funded in part by NRC CR 828790. This abstract does not represent USEPA policy).