Triterpenoid saponins from Stauntonia chinensis

A new triterpenoid saponin, named stauntoside A (1) along with four known saponins (2,3,4,5) was isolated from Stauntonia chinensis DC., (Lardizabalaceae). Their structures were elucidated by spectroscopic analysis and chemical methods as 3-O-alpha-L-arabinopyranosyl-30-norhederagenin -28-O-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl ester (1), 3-O-alpha-L-arabinopyranosyl-30- norhederagenin-28-O-alpha-L-rhamnopyranosyl-(1 --> 4)-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl ester (2), 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-alpha-L-arabinopyranosyl-30-norhederagenin-28-O-alpha-L- rhamnopyranosyl-(1 --> 4)-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl ester (3), 3-O-alpha-L- arabinopyranosyl-hederagenin-28-O-alpha-L-rhamnopyranosyl-(1 --> 4)-beta-D-glucopyranosyl-(1 --> 6)-beta-D- glucopyranosyl ester (4), 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-alpha-L-arabinopyranosyl-hederagenin -28-O-alpha-L-rhamnopyranosyl-(1 --> 4)-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl ester (5). The (1)H and (13)C NMR data for Glycoside L-G1 or Sinofoside A are paradox in the reported before. Thus, the structure elucidation of saponin 2, known as Glycoside L-G1 or Sinofoside A, was discussed and the unambiguous assignments were given.