Triterpene saponins with gastroprotective effects from tea seed (the Seeds of Camellia sinensis)

摘要: Six new triterpene saponins, theasaponins A1 (1), A2 (2), A3 (3), F1 (4), F2 (5), and F3 (6), were isolated from the saponin fraction of seeds Camellia sinensis. The stereostructures 1−6 elucidated on basis chemical physicochemical evidence. Theasaponin (2) showed an inhibitory effect ethanol-induced gastric mucosal lesions in rats at a dose 5.0 mg/kg, p.o., its activity was more potent than that omeplazole. Structure−activity relationships for gastroprotective activities may be suggested as follows:  (1) 28-acetyl moiety enhances activity; having 23-aldehyde group exhibit those with 23-hydroxymethyl or 23-methoxycarbonyl group.