Inhibitory effects of commonly used herbal extracts on UGT1A1 enzyme activity.
Summary of "Inhibitory effects of commonly used herbal extracts on UGT1A1 enzyme activity."
Commonly used herbal supplements were screened for their potential to inhibit UGT1A1 activity using human liver microsomes. Extracts screened included ginseng, echinacea, black cohosh, milk thistle, garlic, valerian, saw palmetto, and green tea epigallocatechin gallate (EGCG). Estradiol-3-O-glucuronide (E-3-G) formation was used as the index of UGT1A1 activity. All herbal extracts except garlic showed inhibition of UGT1A1 activity at one or more of the three concentrations tested. A volume per dose index (VDI) was calculated to estimate the volume in which the daily dose should be diluted to obtain an IC(50)-equivalent concentration. EGCG, echinacea, saw palmetto, and milk thistle had VDI values >2.0 L per dose unit, suggesting a higher potential for interaction. Inhibition curves were constructed for EGCG, echinacea, saw palmetto, and milk thistle. IC(50) values were (mean +/- SE) 7.8 +/- 0.9, 211.7 +/- 43.5, 55.2 +/- 9.2, and 30.4 +/- 6.9 microg/ml for EGCG, echinacea, saw palmetto, and milk thistle extracts, respectively. Based on our findings, inhibition of UGT1A1 by milk thistle and EGCG and to a lesser extent by echinacea and saw palmetto is plausible, particularly in the intestine where higher extract concentrations are anticipated. Further clinical studies are warranted.
Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL, USA.
This article was published in the following journal.
Name: Xenobiotica; the fate of foreign compounds in biological systems
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20666626
- DOI: http://dx.doi.org/10.3109/00498254.2010.505669
Medical and Biotech [MESH] Definitions
Drugs, Chinese Herbal
Chinese herbal or plant extracts which are used as drugs to treat diseases or promote general well-being. The concept does not include synthesized compounds manufactured in China.
Leukemia Inhibitory Factor
An INTERLEUKIN-6 related cytokine that exhibits pleiotrophic effects on many physiological systems that involve cell proliferation, differentiation, and survival. Leukemia inhibitory factor binds to and acts through the lif receptor.
Compounds which restore enzymatic activity by removing an inhibitory group bound to the reactive site of the enzyme.
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