New antibacterial triterpenoid saponin from Lactuca scariola

A new antibacterial triterpenoid saponin, 3β-O-[α-l-rhamnopyranosyl]-30-norolean-12,19-diene-28-oic acid 28-O-[β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranosyl]-ester (1); has been isolated from the stems of Lactuca scariola. Its structure was determined by chemical degradations and spectral analysis.