New noroleanane-type triterpene saponins with gastroprotective effect and platelet aggregation activity from the flowers of Camellia japonica: Revised structures of camellenodiol and camelledionol

The methanolic extract from the flowers of Camellia japonica was found to e xhibit potent gastroprotective effect on ethanol-induced gastric mucosal le sions in rats and platelet aggregation activity. Through bioassay-guided se paration, three new 28-noroleanane-type triterpene saponins, camelliosides A, B, and C, and an oleanane-type triterpene saponin, camellioside D, were isolated from the methanolic extract. The absolute stereostructures of came lliosides A-D were determined on the basis of physicochemical and chemical evidence, which included the structure revision of the triterpene part, cam ellenodiol and camelledionol, using X-Ray crystallographic analysis and mod ified Mosher's method. Camelliosides A and B showed gastroprotective and pl atelet aggregating effects.