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In vitro inhibition of CYP3A4 by herbal remedies frequently used by cancer patients
Author(s) -
Engdal Silje,
Nilsen Odd Georg
Publication year - 2009
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.2750
Subject(s) - cyp3a4 , pharmacology , traditional medicine , ketoconazole , chemistry , in vitro , phytotherapy , metabolism , medicine , cytochrome p450 , biology , biochemistry , antifungal , microbiology and biotechnology , alternative medicine , pathology
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‐ β ‐OH‐testosterone was quantified by a validated HPLC methodology. Green tea was the most potent inhibitor of CYP3A4 metabolism (IC 50 : 73 µg/mL), followed by Agaricus, mistletoe and noni juice (1324, 3594, >10 000 µg/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. Copyright © 2009 John Wiley & Sons, Ltd.