HPLC profile analysis of hepatoprotective oleanene-glucuronides in Puerariae Flos

In order to confirm the constitution of hepatoprotective oleanene glucuronide (OG), HPLC profile analyses of the total OG fractions of both Puerariae Thomsonii Flos (the flowers of Pueraria thomsonii) and Puerariae Lobatae Flos (the flowers of P. lobata) were performed. No remarkable difference in the HPLC profiles with respect to OGs in the flowers was shown, in contrast to those of the roots. By repeated chromatography of the total OG fraction of Puerariae Thomsonii Flos, soyasaponin I (1), kaikasaponin III (2) and kakkasaponin I (3), which had been already isolated from Puerariae Lobatae Flos, were obtained. The hepatoprotective activity of 2 towards immunologically induced liver injury was significantly more effective than that of 1. This information supported previously obtained structure-hepatoprotective relationship data which was measured on another model. The structure-activity relationship information which suggested that the hydroxymethyl group of the galactosyl unit would enhance the hepatoprotective activity was also substantiated.