Triterpenoid saponins and sapogenins from Vaccaria segetalis

Four new triterpenoid saponins, vaccarosides E, F, G and H were isolated from the seeds of Vaccaria segatalis and were respectively defined to be 3-O-beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl] quillaic acid 28-O-beta-D-xylopyranosyl-(1-->4)-chi-L-rhamnopyranosyl-(1-->2)- [chi-L-arabinofuranosyl-(1-->3)]-beta-D-4-O-acetylfucopyranoside; 3-O-[beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl] 3beta,4chi,16chi-trihydroxy-23-norolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl-(1-->4)-chi-L-rhamnopyranosyl-(1-->2)- [chi-L-arabinofuranosyl-(1-->3)]-beta-D-4-O-acetylfucopyranoside; 3-O-[beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl] gypsogenin 28-O-beta-D-xylopyranosyl-(1-->4)-chi-L-rhamnopyranosyl-(1-->2)- [chi-L-arabinofuranosyl (1-->3)]-beta-D-4-O-acetylfucopyranoside; and 3-O-[beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl] 3beta,4chi-dihydroxy-23norolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl-(1-->4)-chi-L-rhamnopyranosyl-(1-->2) -chi-L-arabinofuranosyl-(1-->3)]-beta-D-4-O-acetyfucopyranoside. Their structures were established on the basis of extensive NMR (DEPT, COSY, HOHAHA, HETCOR, HMBC AND NOESY), FAB-MS and ESI-MS studies as well as chemical strategies and enzymatic degradation. The new aglycones of two of the saponins have been designated as segetalic acid and vaccaric acid, respectively.