Nadph Dependent Cytochrome P-450 Reactions- Mode Of Inhibition By The N—Butanol Fraction Of Desmodium Adscendens
Date
1996-03
Authors
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Journal ISSN
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Publisher
University of Ghana
Abstract
The n-butanol fraction (nBF) of Desrrodlvm a d scen d en s , a plant used for the
management of asthma, is' an inhibitor of NADFH-dependent cytochrorre P-450
(CYP) reactions. Its mechanism of action as an inhibitor is hcwever not
kncwn.
In this study, flavoprotein reductase activity, spectral changes associated
with binding and spectral properties of reduced cytochrcme c and CYP were
used to investigate the mode of inhibition.
nBF reduced cytochrane c but not CYP directly. In the presence of NADFH,
the rate of formation of CYP2* (the reduced form of CYP) v\as enhanced ty
the addition of nBF. These effects were observed in reactions without
substrate, indicating that in the absence of a substrate, nBF does noc
prevent the NADPH reduction of CYP, but rather enhances it.
In the presence of a substrate, as exemplified ty a spectrophotometric
assay of the ERCD reaction, nBF v*as found to change the spectrum of
oxidized CYP. The results indicate that in the presence of nBF, the
binding site of CYP is altered to prevent substrate binding.
Description
Thesis(M.Phil)_University of Ghana,1996.