Triterpenoid saponins from Pterocephalus hookeri

Four new triterpenoid saponins, named hookerosides A-D, were isolated from Pterocephalus hookeri. Based on chemical and spectral evidence, their structures were determined as 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-xylopyranosyl(1-->3)-alpha-L- Rhamnopyranosyl(1-->2)-beta-D-xylopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranoside, 3-O-beta-D-xylopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->4)-beta-D- xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)-beta-D-xylopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranoside, 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-xylopyranosyl(1-->4)-beta-D- glucopyranosyl(1-->4)-beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosy l(1-->2 ) beta-D-xylopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl(1-->6)-beta-glucopyranoside and oleanolic acid 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D- xylopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->4)-beta-D-xylopyranosyl(1 -->3)- alpha-L-rhamnopyranosyl(1-->2)-beta-D-xylopyranoside, respectively.