Four new dimeric triterpene glucosides from Sanguisorba officinalis

In search for bioactive compounds from the roots of Sanguisorba officinalis L. (Rosaceae), four new dimeric triterpene glucosides, namely sanguidioside A, B, C, and D () were isolated. Alkaline hydrolysis of afforded the corresponding dimeric aglycones ( and ). Meanwhile, a ready intra-molecular transesterification was observed, providing dimeric triterpenes and . Alkaline hydrolysis of the crude dimmeric saponin also provided a new dimeric triterpene, sanguidiogenin (). The structures of all these compounds are elucidated via spectroscopic and chemical methods, and are further confirmed by the X-ray diffraction analysis of the dimeric aglycone . Compound represents the first dimeric saponin of an oleanolic acid and an ursonic acid derivative, while compound is the first dimeric saponin of oleanolic acid derivatives.