Inhibition of benzodiazepine binding in vitro by amentoflavone, a constituent of various species of Hypericum
Flower extracts of Hypericum perforatum, Hypericum hirsutum, Hypericum patulum and Hypericum olympicum efficiently inhibited binding of [3H]flumazenil to rat brain benzodiazepine binding sites of the GABAA-receptor in vitro with IC50 values of 6.83, 6.97, 13.2 and 6.14 μg/ml, respectively. Single co...
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Published in | Pharmaceutica acta Helvetiae Vol. 72; no. 3; pp. 153 - 157 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Switzerland
Elsevier B.V
01.06.1997
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Subjects | |
Online Access | Get full text |
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Summary: | Flower extracts of Hypericum perforatum, Hypericum hirsutum, Hypericum patulum and Hypericum olympicum efficiently inhibited binding of [3H]flumazenil to rat brain benzodiazepine binding sites of the GABAA-receptor in vitro with IC50 values of 6.83, 6.97, 13.2 and 6.14 μg/ml, respectively. Single constituents of the extracts like hypericin, the flavones quercetin and luteolin, the glycosylated flavonoides rutin, hyperoside and quercitrin and the biflavone I3, II8-biapigenin did not inhibit binding up to concentrations of 1 μM. In contrast, amentoflavone revealed an IC50 = 14.9 ± 1.9 nM on benzodiazepine binding in vitro. Comparative HPLC analyses of hypericin and amentoflavone in extracts of different Hypericum species revealed a possible correlation between the amentoflavone concentration and the inhibition of flumazenil binding. For hypericin no such correlation was observed. Our experimental data demonstrate that amentoflavone, in contrast to hypericin, presents a very active compound with regard to the inhibition of [3H]-flumazenil binding in vitro and thus might be involved in the antidepressant effects of Hypericum perforatum extracts. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0031-6865 |
DOI: | 10.1016/S0031-6865(97)00002-2 |