Conyzasaponins I-Q, nine new triterpenoid Saponins from Conyza blinii

Nine new triterpenoid saponins, conyzasaponins I-Q (1-9), were isolated from the aerial parts of Conyza blinii. Their structures were established on the basis of extensive 1D and 2D NMR spectra as well as by chemical degradations. Among these compounds, conyzasaponins M-O (5-7) share a common pentasaccharide unit attached to C-28 of the aglycon, 28-O-beta-D-apiofuranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl ester, which contains two apiofuranosyl residues. To the best of our knowledge, they are among the few examples of natural products possessing two apiofuranose units in a single sugar chain.