SAPONINS FROM TRIDESMOSTEMON-CLAESSENSSI

Two new saponins have been isolated fromTridesmostemon claessenssi and their structures determined using a combination of1H and13C NMR, and californium plasma desorption mass spectrometry. They are 3-O-[β-d- glucopyranosyl-(1→6)-β-d-glucopyranosyl]-28-O-[α-l-rhamn opyranosyl(1→3)-β-d-Xylopyranosyl-(1→4)-(α-l-rhamno pyranosyl-(1→3))-α-l-rhamnopyranosyl-(1→2)-β-d-xylo pyranosyll-16α-hydroxyprotobassic acid for which we propose the name of tridesmosaponin A and 3-O-[α-l-rhamnopyranosyl]-28-O-[(α-l-rhamnopyranosyl- (1→3))-(α-l- rhamnopyranosyl]-(1→4))-β-d-Xylopyranosyl-(1→4)-α-l -rhamnopyranosyl-(1→2)-β-d-xylopyranosyl]-16α-hydroxy- protobassic acid which we propose to name tridesmosaponin B. Their genin is the novel triterpene, 16α- hydroxyprotobassic acid. The ester chain of sugars is characterized by the unusual1C4 conformation of its β-d-Xylose. © 1990 Pergamon Press plc.