Oleanene-type triterpene glycosides from Puerariae Radix. II. Isolation of saponins and the application of tandem mass spectrometry to their structure determination.

A continuing study of the ingredients of Puerariae Radix, the roots of Pueraria lobata (WILLD.) OHWI, which is one of the most important crude drugs, has resulted in the first isolation of four new oleanene-type triterpene glycosides, named kudzusaponins SA1, SA2, SA3 and C1 (1-4). Their structures were determined to be 3-O-beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl soyasapogenol A (1), 3-O-beta-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl soyasapogenol A 22-O-alpha-L-arabinopyranoside (2), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-D- glucuronopyranosyl kudzusapogenol C 21-O-beta-D-glucopyranoside (4), respectively. The usefulness of tandem mass spectrometry in the structural determination of oleanene-type triterpene bisdesmosides is also discussed.