A new Monooxygenase Product from 7-Ethoxycoumarin and its Relation to the O-Dealkylation Reaction
- 1 January 1985
- journal article
- research article
- Published by Walter de Gruyter GmbH in Biological Chemistry Hoppe-Seyler
- Vol. 366 (1) , 23-32
- https://doi.org/10.1515/bchm3.1985.366.1.23
Abstract
The widely used fluorometric microsomal monooxygenase test for 7-ethoxycoumarin O-dealkylation was reinvestigated with regard to other possible hydroxylation products. By HPLC(high-performance liquid chromatography)-analysis no .beta.-hydroxylation of the ethyl group and no 8-hydroxylation could be detected. Only a smalll percentage of 6-hydroxylation occurred, but as a new metaboite 7-ethoxy-3-hydroxycoumarin was found in quantities depending on the microsomal preparation used. The ratio of O-delakylation to 3-hydroxylation varied according to species, induction, buffer and pH, suggesting that different isozymes of cytochrome P450 were involved. The isozyme mainly responsible for 3-hydroxylation exhibited a great dependence on cytochrome b5 as the donor for the second electron. The fluorometric test does not include 3-hydroxylation due to the virtual absence of an emission spectrum above 450 nm.This publication has 25 references indexed in Scilit:
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