TY - JOUR T1 - EFFECTS OF HERBAL EXTRACTS ON THE FUNCTION OF HUMAN ORGANIC ANION-TRANSPORTING POLYPEPTIDE OATP-B JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 577 LP - 582 DO - 10.1124/dmd.105.007872 VL - 34 IS - 4 AU - Hiromi Fuchikami AU - Hiroki Satoh AU - Masayuki Tsujimoto AU - Shigehiro Ohdo AU - Hisakazu Ohtani AU - Yasufumi Sawada Y1 - 2006/04/01 UR - http://dmd.aspetjournals.org/content/34/4/577.abstract N2 - Most known interactions between herbal extracts and drugs involve the inhibition of drug-metabolizing enzymes, but little is yet known about the possible role of transporters in these interactions. In this study, we have examined the effects of herbal extracts used in dietary supplements on the function of organic anion-transporting polypeptide B (OATP-B; OATP2B1), which is expressed on human intestinal epithelial cells and is considered to be involved in the intestinal absorption of various drugs. Specifically, the effects of 15 herbal extracts on uptake of estrone-3-sulfate, a typical OATP-B substrate, by human embryonic kidney 293 cells stably expressing OATP-B were evaluated. At concentration levels considered likely to be attainable in the human intestine, extracts of bilberry, echinacea, green tea, banaba, grape seed, ginkgo, and soybean potently inhibited estrone-3-sulfate uptake by 75.5, 55.5, 82.1, 61.1, 64.5, 85.4, and 66.8%, respectively (P < 0.01). The inhibitory effect of ginkgo leaf extract was concentration-dependent (IC50 = 11.2 ± 3.3 μg/ml) and reversible. Moreover, flavonol glycosides and catechins significantly inhibited the function of OATP-B, suggesting that the inhibitory effects of the herbal extracts on OATP-B may be primarily attributable to flavonoids. The extracts of mulberry, black cohosh, and Siberian ginseng moderately (but significantly) inhibited estrone-3-sulfate uptake by 39.1, 47.2, and 49.2%, respectively (P < 0.05). Extracts of barley, Job's tears, rutin, rafuma, and passionflower were ineffective. These results suggest that coadministration of some dietary supplements may decrease the absorption of orally administered substrates of OATP-B. The American Society for Pharmacology and Experimental Therapeutics ER -