Enzymatic degradation of the triterpenoid saponin helianthoside 2.

Helianthoside 2 (1), the main bisdesmosidic saponin of Helianthus annuus L. was converted to the products 2, 3 and 4 by several, optimized enzymatic hydrolysis methods. Monosaccharide units of the acylglycosidic at C-28 of the sapogenin bonded, linear chain oligosaccharide were cleaved, but the branched trisaccharide at C-3 of the aglycone are stable under the conditions used. Compounds 2 and 3 are new triterpenoid glycosides, which were characterized as 28-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranoside (2) and 28-O-alpha-L-arabinopyranoside (3) of 3-O-[alpha-L-rhamnopyranosyl-(1-->3)][beta-D-xylopyranosyl-(1-->4)] beta-D-glucopyranoside of 3 beta,16 alpha-dihydroxy-olean-12-en-28-oic acid.