HPLC-based activity profiling of Angelica pubescens roots for new positive GABAA receptor modulators in Xenopus oocytes

A petroleum ether extract of the traditional Chinese herbal drug Duhuo (roots of Angelica pubescens Maxim. f. biserrata Shan et Yuan), showed significant activity in a functional two-microelectrode voltage clamp assay with Xenopus oocytes which expressed recombinant γ-aminobutyric acid type A (GABAA) receptors of the subtype α1β2γ2S. HPLC-based activity profiling of the active extract revealed six compounds responsible for the GABAA receptor modulating activity. They were identified by microprobe NMR and high resolution mass spectrometry as columbianetin acetate (1), imperatorin (3), cnidilin (4), osthol (5), and columbianedin (6). In concentration-dependent experiments, osthol and cnidilin showed the highest potentiation of the GABA induced chloride current (273.6% ± 39.4% and 204.5% ± 33.2%, respectively at 300 μM). Bisabolangelone (2) only showed minor activity at the GABAA receptor. The example demonstrates that HPLC-based activity profiling is a simple and efficient method to rapidly identify GABAA receptor modulators in a bioactive plant extract.

Graphical AbstractFigure optionsDownload as PowerPoint slideHPLC-based activity profiling of Angelica pubescens roots enabled the identification of coumarins which modulate GABAA receptors of the α1β2γ2S subtype in a two-microelectrode voltage clamp assay with Xenopus oocytes.