Linked Life Data

9193873

Source:http://linkedlifedata.com/resource/pubmed/id/9193873

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1997-8-15
pubmed:abstractText
The forms of cytochrome P450 involved in the stereoselective S-oxidation of flosequinan [(+/-)-7-fluoro-1-methyl-3-methylsulfinyl-4-quinolone] were investigated in vitro using liver microsomes from rats and humans. Rat liver microsomes supplemented with NADPH catalyzed the four different S-oxidations, which were from flosequinan sulfide (FS; 7-fluoro-1-methyl-3-methylthio-4-quinolone) to R(+)- and S(-)-flosequinan (R-FSO and S-FSO, respectively) and from R-FSO and S-FSO to flosequinan sulfone (FSO2; 7-fluoro-1-methyl-3-methylsulfonyl-4-quinolone). The activities of all the S-oxidases in liver microsomes from male rats were higher than those from female rats. The activities of the S-oxidases measured at a high substrate concentration (1 mM) were induced by treatment of rats with phenobarbital and dexamethasone. Treatment of rats with 3-methylcholanthrene also induced the activities, but only at a low substrate concentration (50 microM), except for the S-oxidase catalyzing the reaction from FS to R-FSO. Enzymes induced by clofibrate and ethanol were not involved in the oxidations at a low substrate concentration. The activities of S-oxidases were correlated with the contents of cytochrome P450 (CYP)3A enzymes. Anti-CYP3A2 antisera inhibited the activities of the S-oxidases catalyzing the reactions from FS to R-FSO (40%) and to S-FSO (60%) at the high substrate concentration and inhibited the activities of the S-oxidases, thus catalyzing reactions from R-FSO and S-FSO to FSO2 (70%) at both high and low substrate concentrations. These results suggest that CYP3A is the major enzyme involved in all S-oxidation pathways in flosequinan metabolism in rats. On the other hand, except for the S-oxidation of FS to R-FSO, the rates of the other three S-oxidations by liver microsomes from 30 individual humans correlated highly with each other, suggesting that the same enzyme would be involved in the three S-oxidations. Anti-CYP3A2 antisera inhibited the activities of all the S-oxidases in human liver microsomes ranging from 40 to 80%, suggesting that CYP3A is also involved in all of the S-oxidations of flosequinan in humans.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0090-9556
pubmed:author
pubmed:issnType
Print
pubmed:volume
25
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
716-24
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Cytochrome P450 responsible for the stereoselective S-oxidation of flosequinan in hepatic microsomes from rats and humans.
pubmed:affiliation
Division of Drug Metabolism, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't