Effects of herbal products and their constituents on human cytochrome P450(2E1) activity.
Ethanolic extracts from fresh Echinacea purpurea and Spilanthes acmella and dried Hydrastis canadensis were examined with regard to their ability to inhibit cytochrome P450(2E1) mediated oxidation of p-nitrophenol in vitro. In addition, individual constituents of these extracts, including alkylamides from E. purpurea and S. acmella, caffeic acid derivatives from E. purpurea, and several of the major alkaloids from H. canadensis, were tested for inhibition using the same assay. H. canadensis (goldenseal) was a strong inhibitor of the P450(2E1), and the inhibition appeared to be related to the presence of the alkaloids berberine, hydrastine and canadine in the extract. These compounds inhibited 2E1 with K(I) values ranging from 2.8 microM for hydrastine to 18 microM for berberine. The alkylamides present in E. purpurea and S. acmella also showed significant inhibition at concentrations as low as 25 microM, whereas the caffeic acid derivatives had no effect. Commercial green tea preparations, along with four of the individual tea catechins, were also examined and were found to have no effect on the activity of P450(2E1).
The University of North Carolina at Greensboro, Department of Chemistry and Biochemistry, 414 Science Building, Greensboro, NC 27402, USA. gmraner@uncg.edu
Gregory M
GM
Raner
Sean
S
Cornelious
Kamalika
K
Moulick
Yingqing
Y
Wang
Ashley
A
Mortenson
Nadja B
NB
Cech
D016367:Baculoviridae / Q000201:enzymology; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects*; D020900:Echinacea; D006368:Helianthus; D006801:Humans; D039321:Hydrastis; D008862:Microsomes, Liver / Q000201:enzymology; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D018517:Plant Roots; D010946:Plants, Medicinal
D065607:Cytochrome P-450 Enzyme Inhibitors; D010936:Plant Extracts; D003577:Cytochrome P-450 Enzyme System