STRUCTURES OF 3 NEW OLEANENE GLUCURONIDES ISOLATED FROM LATHYRUS-PALUSTRIS VAR. PILOSUS AND HEPATOPROTECTIVE ACTIVITY

Three new saponins, named palustrosides I, II and III, together with a zukisaponins II, V and soyasapogenol B monoglucuronide, were isolated from the aerial parts of Lathylus palustris L. var. pilosus LEDEB. The structures of palustrosides I, II and III were identified as glucopyr anosyl-(1-->2)-beta-D-glucuronopyranosides of soyasapogenol E, abrisap ogenol E, and bredemolic acid 28-O-beta-D-glucopyranoside, respectivel y, by spectroscopic and chemical methods. As part of our studies on he patoprotective drugs, we also examined the hepatoprotective effects of these saponins towards immunologically induced liver injury in primar y cultured rat hepatocytes. The activity of the disaccharide group was greater than that of the trisaccharide group. This information regard ing the structure-activity relationships substantiated previously obta ined data. Structure-hepatoprotective relationships for the sapogenol moiety suggested that the hydroxyl group at C-30 reduces the hepatopro tective effect. On the other hand, the carbonyl group at C-22 may be e quivalent to a hydroxyl group at C-22 in terms of hepatoprotective act ion. Oleanolic acid-type saponins also exhibited hepatoprotective acti on.