• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.27.2-27.2
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• 2008

• Journal of Life Science
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• v.18 no.9
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• pp.1244-1248
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• 2008

P-glycoprotein (P-gp) is a very important drug transporter, which plays an important role in drug disposition and represents an additional mechanism for the development of multidrug resistance. Flavonoids, a major class of natural compounds widely present in foods and herbal products, have been shown to be P-gp inhibitors. The objective of the present study was to identify new chemosensitizer candidates through the screening of various herbal extracts. The inhibitory effects of herbal extracts on P-gp activity were assessed by measuring accumulation of calcein AM using P-gp overexpressed L-MDR1 cells. Curcuma longa showed the most potent inhibition on P-gp function. The inhibitory potential of P-gp was in the order: Curcuma longa > Curcuma aromatica > Ageratum conizoids > Zanthoxylum planispinum > Zedoariae rhizome > Rakta chandan > Dalbergia odorifera > Caesalpinia Sappan > Aloe ferox. To identify individual constituents with inhibitory activity, the herbal extracts were analyzed by LC/MS/MS. Several flavonoids such as curcumin, a well-known P-gp inhibitor, were identified through mass spectral library search. These in vitro data indicate that herbal extracts contain constituents that can potently inhibit the activities of P-gp and suggest that these herbal extracts should be examined for potential chemosensitizer in vivo.