A new triterpenoid saponin with inhibition of luteal cell from the seeds of Vaccaria segetalis.

A new triterpenoid saponin, named segetoside B, showing inhibition of luteal cell activity, has been isolated from the seeds of Vaccaria segetalis. On the basis of chemical reactions and spectral analyses, its structure has been established as 28-O-[beta-D-xylopyranosyl-(1 --> 4)-alpha-L-rhamnopyranosyl-(1 --> 2)]-[alpha-L-(5-O-acetyl)arabinofuranosyl-(1 --> 3)]-beta-D-(4-O-acetyl)fucopyranosyl-gypsogenin-3-O-beta-D-galactopyranosyl-(1 --> 2)-beta-D-(6-O-methyl ester)-glucuronopyranoside.