| Title | In vitro inhibition of CYP3A4 by herbal remedies frequently used by cancer patients. | | Author(s) | Engdal S, Nilsen OG | | Institution | Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway. silje.engdal@ntnu.no | | Source | Phytother Res 2009 Jul; 23(7):906-12. | | MeSH | Agaricus
Chromatography, High Pressure Liquid
Cytochrome P-450 CYP3A
Enzyme Inhibitors
Herbal Medicine
Humans
Ketoconazole
Plant Extracts
Tea
Testosterone
Viscum album
| | Abstract | The herbal remedies Natto K2, Agaricus, mistletoe, noni juice, green tea and garlic, frequently used by cancer patients, were investigated for their in vitro inhibition potential of cytochrome P-450 3A4 (CYP3A4) metabolism. To our knowledge, only garlic and green tea had available data on the possible inhibition of CYP3A4 metabolism. Metabolic studies were performed with human c-DNA baculovirus expressed CYP3A4. Testosterone was used as a substrate and ketoconazole as a positive quantitative inhibition control. The formation of 6-beta-OH-testosterone was quantified by a validated HPLC methodology. Green tea was the most potent inhibitor of CYP3A4 metabolism (IC(50): 73 microg/mL), followed by Agaricus, mistletoe and noni juice (1324, 3594, >10 000 microg/mL, respectively). All IC(50) values were high compared with those determined for crude extracts of other herbal remedies. The IC(50)/IC(25) ratios for the inhibiting herbal remedies ranged from 2.15 to 2.67, indicating similar inhibition profiles of the herbal inhibitors of CYP3A4. Garlic and Natto K2 were classified as non-inhibitors. Although Agaricus, noni juice, mistletoe and green tea inhibited CYP3A4 metabolism in vitro, clinically relevant systemic or intestinal interactions with CYP3A4 were considered unlikely, except for a probable inhibition of intestinal CYP3A4 by the green tea product. | | Language | eng | | Pub Type(s) | Journal Article
Research Support, Non-U.S. Gov't
| | PubMed ID | 19170155 |
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