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Science Forum Index » Life Extension Forum » Silymarin extracts inhibit CYP450
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| kofi |
 Posted: Wed Dec 31, 2003 10:56 pm |
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Phytother Res. 2002 Nov;16(7):632-8. Related Articles, Links
Click here to read
Effect of silybin and its congeners on human liver microsomal
cytochrome P450 activities.
Zuber R, Modriansky M, Dvorak Z, Rohovsky P, Ulrichova J, Simanek V,
Anzenbacher P.
Faculty of Chemical Technology, University of Pardubice, Nam. Cs.
Legii 565, 532 10 Pardubice, Czech Republic.
Silybin and related flavonolignans form a major part of the Silybum
marianum extract, silymarin, which has been used to treat liver diseases
for hundreds of years. Although regarded as safe, many of the extract
constituents remain thus far untested for their possible effects on
liver biotransformation enzymes. Cytochromes P450 (CYP) are very
important in this regard. We tested the effect of four flavonolignans:
silybin, its hemisynthetic derivative dehydrosilybin, silydianin, and
silycristin on three specific CYP activities: bufuralol 1'-hydroxylation
(CYP2D6), p-nitrophenol hydroxylation (CYP2E1), and nifedipine oxidation
(CYP3A4). All flavonolignans displayed dose-dependent inhibition of
these activities with IC(50) values in the micromolar range. The
inhibition was competitive or mixed as revealed by double reciprocal
plots of kinetic experiments. However, the inhibition is not considered
to be relevant for therapy because physiological concentrations of the
individual flavonolignans do not exceed 0.5 microM. The data support the
use of the extract as a dietary supplement. Copyright 2002 John Wiley &
Sons, Ltd.
PMID: 12410543 [PubMed - indexed for MEDLINE] |
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