Saponins from Fagonia arabica

Seven new triterpenoid saponins were isolated and identified from the aerial parts of Fagonia arabica. They were characterized as 3-O-beta-D-xylopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->3)]-alpha-L- arabinopyranosyl oleanolic acid 28-O-beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->3)]-alpha-L- arabino pyranosyl oleanolic acid 28-O-beta-D-glucopyranoside, 3-O-beta-D-xylopyranosyl(1-->2)-[beta-D-glucopyranosyl (1-->3)]-alpha- L-arabinopyranosyl oleanolic acid, 3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->3)]-alpha-L- arabino pyranosyl oleanolic acid, 3-O-beta-D-xylopyranosyl(1-->2)-[beta-D-glucopyranosyl (1-->3)]-alpha-L-arabinopyranosyl 27-hydroxyoleanolic acid, 28-O-beta-D-glucopyranoside, 3-O-beta-D-xylopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->3)]-alpha-L- arabinopyranosyl ursolic acid 28-O-beta-D-glucopyranoside and 3-O-beta-D-xylopyranosyl (1-->2)-[beta-D-glucopyranosyl (1-->3)-alpha-L-arabinopyranosyl 27-hydroxyursolic acid 28-O-beta-D-glucopyranoside. The structures of the saponins were established by analyses of their 1H and 13C NMR spectra with the aid of 2D experiments. The two genins, 27-hydroxyoleanolic acid and 27-ursolic acid, are new.