Structure Elucidation of Three Triterpenoid Saponins from Alphitonia zizyphoides Using 2D Nmr Techniques

High-field nmr experiments have been used to determine the structures of three new saponins, zizyphoisides C, D, and E [1-3], isolated from Alphitonia zizyphoides, a medicinal plant found in the Samoan rain forest. The saponins consist of the aglycone, jujubogenin, to which are attached three sugar units and an unsaturated side-chain. The three compounds are similar except for the location of an acetyl group on one of the sugar units.