New noroleanane-type triterpene saponins with gastro-protective effect and platelet aggregation activity from the flowers of camellia japonica: revised structures of camellenodiol and camelledionol

摘要

The methanolic extract from the flowers of Camellia japonica was found to exhibit potent gastroprotective effect on ethanol-induced gastric mucosal lesions in rats and platelet aggregation activity. Through bioassay-guided separation, 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 camelliosides A-D were determined on the basis of physicochemical and chemical evidence, which included the structure revision of the triterpene part, camellenoidol and camelledionol, using X-Ray crystallographic analysis and modified Mosher's method. Camelliosides A and B showed gastroprotective and platelet aggregating effects.