From the stem bark of Rhamnus catharticus L. (purging buckthorn) the three main anthraquinone glycosides have been isolated by the new method of droplet-countercurrent-chromatography. Their structures were spectroscopically identified as em odin-8-O-β-gentiobioside, -glucoside and -primveroside. From these the primveroside is a new substance, the gentiobioside has been found for the second time in plant material. The structures were confirmed by 13C NMR spectroscopy for the first time in O-glycosides of emodin type. Especially the differences in 13C chemical shifts of the free resp. acetylated aglycones and glycosides are useful parameters for determining the position of O-glycosylation in the 1,8-dihydroxy-anthraquinone derivatives
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