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pubmed:abstractText |
Ginkgolides A, B, and C are diterpene trilactones and active constituents of the 50:1 Ginkgo biloba leaf extract widely used in the symptomatic treatment of mild to moderate dementia. Using the two-electrode voltage clamp methodology, these ginkgolides were found to be moderately potent antagonists at recombinant human alpha(1)beta(2)gamma(2L) GABA(A) receptors expressed in Xenopus oocytes. Ginkgolides A, B, and C inhibited the direct action of gamma-aminobutyric acid (GABA) with K(i) values of 14.5+/-1.0, 12.7+/-1.7, and 16.3+/-2.4 microM respectively. Antagonism by these ginkgolides at alpha(1)beta(2)gamma(2L) GABA(A) receptors appears to be noncompetitive as indicated by the nonparallel right shift and reduced maximal GABA response in their GABA concentration-effect curves.
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pubmed:affiliation |
Adrien Albert Laboratory of Medicinal Chemistry, Department of Pharmacology, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia.
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