HPLC-based activity profiling--discovery of sanggenons as GABAA receptor modulators in the traditional Chinese drug Sang bai pi (Morus alba root bark).

EtOAc extracts from two batches of Morus alba root bark (Sang bai pi) potentiated γ-aminobutyric acid (GABA)-induced chloride influx in Xenopus oocytes, which transiently expressed GABA (A) receptors of the subunit composition α₁β₂γ(2S). With the aid of HPLC-based activity profiling of the extract from the first batch, activity was traced to a peak subsequently identified as sanggenon G (3). The second batch had a different phytochemical profile, and HPLC-based activity profiling led to the identification of sanggenon C (4) and a stereoisomer of sanggenon D (2) as positive GABA (A) receptor modulators. The structurally related compound kuwanon L (1) was inactive. The sanggenons represent a new scaffold of positive GABA (A) receptor modulators.