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 3-0-alpha-L-arabinopyranosyl-30-norhederagenin-28-0-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl ester (2), 3-0-alpha-L-rhamno-pyranosyl-(1 -> 2)-alpha-L-arabinopyranosyl-30-norhederagenin-28-0-alpha-L-rhamnopyranosyl-(1 -> 4)-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl ester (3), 3-0-alpha-L-arabinopyranosyl-hederagenin-28-0-alpha-L-rhamnopyranosyl-1(1 -> 4)-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl ester (4). 3-0-alpha-L-rhamnopyranosyl-(1 -> 2)-alpha-L-arabinopyranosyl-hederagenin 28-0-alpha-L-rhamnopyranosyl-(1 -> 4)-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl ester (5). The H-1 and C-13 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.