Amentoflavone is found in a number of plants with medicinal properties, including Ginkgo biloba and Hypericum perforatum (St. John's Wort). We have developed a rapid and economic semi-synthetic preparation of amentoflavone from biflavones isolated from autumnal Ginkgo biloba leaves. Several studies have shown that amentoflavone binds to benzodiazepine receptors. Using two electrode voltage-clamp methodology, amentoflavone has been shown to be a negative modulator of GABA at GABA(A) alpha(1)beta(2)gamma(2L) receptors expressed in Xenopus laevis oocytes This action appears to be independent of the flumazenil-sensitive benzodiazepine modulatory sites on the GABA(A) receptor.