@article {Wang:June 2005:0022-3573:751,
	author = "Wang, Yi",
	author = "Cao, Jiang",
	author = "Zeng, Su",
	title = "Involvement of P-glycoprotein in regulating cellular levels of Ginkgo flavonols: quercetin, kaempferol, and isorhamnetin",
	journal = "Journal of Pharmacy and Pharmacology",
	volume = "57",
	year = "June 2005",
	abstract = "Quercetin, kaempferol, and isorhamnetin were the most important flavonoid constituents in extracts from <I>Ginkgo biloba</I> leaves. Transport studies of Ginkgo flavonols were performed in Caco-2 cell mono-layers. Their apparent permeability in absorptive and secretion directions was determined, and quercetin, kaempferol and isorhamnetin displayed polarized transport, with the P<SUB>app,B-A</SUB> being higher than the P<SUB>app,A-B</SUB>(<I>P</I> &#060; 0.01 for quercetin, <I>P</I> &#060; 0.001 for kaempferol and isorhamnetin, Student's <I>t</I>-test ). Bcap37/MDR1 cells, which were transfected with a P-glycoprotein (P-gp) gene construct, were treated with quercetin, kaempferol or isorhamnetin. The concentrations of Ginkgo flavonol in Bcap37/MDR1 cells were lower than those in parent cells (<I>P</I> &#060; 0.05 for quercetin, <I>P</I> &#060; 0.01 for isorhamnetin, Mann-Whitney U test). The concentrations of the flavonol in transfected cells increased when incubated with the P-gp inhibitor verapamil (<I>P</I> &#060; 0.05 for kaempferol, Mann-WhitneyU test). A colorometric assay for ATPase activity was applied to the detection of interaction of flavonol with P-gp. Quercetin and kaempferol inhibited the ATPase activity, and isorhamnetin stimulated the ATPase activity (<I>P</I> &#060; 0.05 for isorhamnetin, Mann Whitney U test). The results indicated that Ginkgo flavonols quercetin, kaempferol and isorhamnetin were substrates of P-gp. The P-gp type efflux pump might limit the bioavailability of Ginkgo flavonols.",
	pages = "751-758(8)",
	url = "http://www.ingentaconnect.com/content/rpsgb/jpp/2005/00000057/00000006/art00010"
	doi = "doi:10.1211/0022357056299"
}