Sweet and bitter principles of the Chinese plant drug, Bai-Yun-Shen: Revision of the assignment of the source plant and isolation of two new diterpene glycosides.

Abstract

The assignment of the source plant of the Chinese plant drug "Bai-Yun-Shen" as Salvia digitaloides DIELS (Labiatae), was revised to Phlomis betonicoides DIELS of the same family. From roots of this plant, a sweet glycoside named phlomisoside-I (5) and a bitter glycoside named phlomisoside-II (6) were isolated. The aglycone of both compounds was proved to be baiyunol (7, furano-labdane-type diterpene), the aglycone of baiyunoside (1), which has already been isolated as the sweet principle from this plant drug. The structures of 5 and 6 were elucidated as the 3-O-α-rhamnopyranosyl-(1→2)-β-glucopyranoside and the 3-O-sophoroside of 7, respectively.