A new triterpenoid saponin, namely pomatoside A (3) 13beta, 28-epoxy-16-oleananone-3-O-[alpha-L-rhamnopyranosyl-(1 -->6)-O-beta-D-glucopyranosyl-(1 -->4)-O-beta-D-glucopyranosyl-(1 -->6)-O-beta-D-glucopyranosyl-(1 -->2)]-beta-D-glucopyranoside, together with twelve known compounds, was isolated for the first time from Pomatosace filicula Maxim., a monotypic endemic plant, grown in the Qinghai-Xizang Plateau of China. Their structures were elucidated by spectroscopic analyses and chemical methods, especially 2D-NMR.
