Six New Coumarin Glycosides from the Aerial Parts of Gendarussa vulgaris

Six new coumarin glycosides, genglycoside A–F (1–6), were isolated from the aerial parts of Gendarussa vulgaris, along with ten known analogues (7–16). Their structures were unambiguously established on the basis of extensive spectroscopic data and HPLC analysis. The cytotoxic activities of all isolated compounds were evaluated by MTT assay. Compound 12 showed the most potent cytotoxicity in Eca-109, MCF-7, and HepG2 cell lines. By the preliminary structure–activity relationships, it was firstly discovered that the glycosylation or esterification at 7,8-dihydroxy or 7-hydroxy drastically reduced the cytotoxic activity of the parent coumarin.