Isolation and Structural Elucidation of DDMP-Conjugated Soyasaponins as Genuine Saponins from Soybean Seeds

摘要

The composition and the structures of native #x201c;group B saponin#x201d; in soybean seeds were reinvestigated. Five kinds of saponins named soyasaponins#x3b1;g,#x3b2;g,#x3b2;a,#x3b3;g, and#x3b3;a, according to elution order from HPLC, were isolated and the structures were characterized as 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) attaching through an acetal linkage to the C-22 hydroxyl of the aglycones of soyasaponins V, I, II, III, and IV, respectively, by UV, IR, MS, and NMR. DDMP-conjugated saponins were detected as major saponin constituents by extraction under mild conditions, and soyasaponins I#x2013;V were not detected. Therefore it was strongly suggested that these DDMP-conjugated saponins were genuine saponins in the intact soybeans.