Document Detail


Formation of 4-hydroxyochratoxin A from ochratoxin A by rat liver microsomes.
MedLine Citation:
PMID:  7396488     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Hydroxyochratoxin A was isolated and identified from the urine of rats after injection with ochratoxin A. By incubating ochratoxin A with rat liver microsomes and reduced nicotinamide adenine dinucleotide phosphate, one major (90%) and two minor metabolites, more polar than ochratoxin A, were formed. Thin-layer chromatography revealed that the major metabolite had Rf values identical to those of hydroxyochratoxin A in six different solvent systems. Formation of the metabolites in vitro was inhibited by carbon monoxide and by metyrapone, and the rate of formation increased after pretreatment of the rats with phenobarbital. A type I spectrum appeared upon binding of ochratoxin A to microsomes with a spectral dissociation constant (Ks) of 37.6 microM. These findings strongly suggest the involvement of a cytochrome P-450 in the hydroxylation of ochratoxin A by rat liver microsomes. Apparent Km and Vmax values for the formation of hydroxyochratoxin A were determined to 50 microM and 5.5 nmol/mg of protein per h, respectively.
Authors:
F C Størmer; J I Pedersen
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  39     ISSN:  0099-2240     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  1980 May 
Date Detail:
Created Date:  1980-09-23     Completed Date:  1980-09-23     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  971-5     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Chromatography, Thin Layer
Cytochrome P-450 Enzyme System / metabolism
Hydroxylation
Male
Mass Spectrometry
Metabolic Detoxication, Drug
Microsomes, Liver / drug effects,  metabolism*
Ochratoxins / metabolism*,  urine
Phenobarbital / pharmacology
Rats
Chemical
Reg. No./Substance:
0/Ochratoxins; 303-47-9/ochratoxin A; 35299-87-7/4-hydroxyochratoxin A; 50-06-6/Phenobarbital; 9035-51-2/Cytochrome P-450 Enzyme System
Comments/Corrections

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