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Detoxication Pathways Involving Glutathione and Epoxide Hydrolase in the in Vitro Metabolism of Chloroprene

Lookup NU author(s): Dr Tony Munter, Professor Bernard Golding, Professor William Watson

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Abstract

Chloroprene (2-chloro-1,3-butadiene, 1) is an important industrial chemical, which is carcinogenic in experimental animals and possibly in humans. It is metabolized to the monoepoxides, 2-chloro-2-ethenyloxirane (2a,b) and (1-chloroethenyl)oxirane (3a,b), together with electrophilic chlorinated aldehydes and ketones. This study has investigated the detoxication of these chloroprene metabolites in vitro by glutathione (GSH) and epoxide hydrolase (EH) in liver microsomes from Sprague-Dawley rats, B6C3F1 mice, and humans. In incubations of chloroprene with liver microsomes containing GSH, several GSH conjugates were identified. These were 1-hydroxy-4-(S-glutathionyl)butan-2-one (13), 1,4-bis-(S-glutathionyl)butan-2-one (15), and (Z)-2-(S-glutathionyl)but-2-en-l-al (16). A fourth GSH conjugate was identified as either 2-chloro-3-hydroxy-4-(S-glutathionyl)butene (12a,b) or 1-chloro-4-(S-glutathionyl)-butan-2-one (14), which were indistinguishable by LC/MS. Structural assignments of metabolites were based on chromatographic and spectroscopic comparisons with synthetic standards. There were significant differences between species in the amounts of 3a,b formed in microsomal incubations, the order being mouse > rat > human. Hydrolysis by microsomal EHs showed a distinct selectivity for S-(1-chloroethenyl)oxirane (3b) resulting in an accumulation of the R-enantiomer; the ratio of the amounts between species was 20:4:1 for mouse:rat: human, respectively.


Publication metadata

Author(s): Munter T, Cottrell L, Golding BT, Watson WP

Publication type: Article

Publication status: Published

Journal: Chemical Research in Toxicology

Year: 2003

Volume: 16

Issue: 10

Pages: 1287-1297

Print publication date: 01/10/2003

ISSN (print): 0893-228X

ISSN (electronic): 1520-5010

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/tx034107m

DOI: 10.1021/tx034107m

PubMed id: 14565770


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