Saponin and sapogenol. XXXVIII. Structure of soyasaponin A2, a bisdesmoside of soyasapogenol A, from soybean, the seeds of Glycine max Merrill.

Abstract

Two new bisdesmosides of soyasapogenol A (1), named soyasaponin A1 and soyasaponin A2 (7), were isolated from soybean, the seeds of Glycine max MERRILL, together with the known soyasaponins I (4), II (5), and III (6). By employing a photochemical degradation method, which is a selective cleavage method for the glucuronide linkage in oligoglycosides, and on the bases of spectral analyses and chemical reactions, the structure of soyasaponin A2 was elucidated as 3-O-[β-D-galactopyranosyl (1→2)-β-D-glucuronopyranosyl]-22-O-[β-D-glucopyranosyl (1→3)-α-L-arabinopyranosyl] soyasapogenol A (7).