Isolation and structure determination of acetylated triterpenoid saponins from the seeds of Centratherum anthelminticum

Phytochemical investigation of Centratherum anthelminticum seeds resulted in the isolation of two novel glycosides. The pentacyclic triterpenoid saponins were shown to contain hederagenin and sugar residues forming two glycosyl chains. The structural analysis of its acetylated derivative was determined using a combination of homo- (1D 1H NMR, 13C NMR and 13C NMR-DEPT) and heteronuclear 2D NMR techniques (1H-1H-COSY, total correlated spectroscopy (TOCSY), heteronuclear multiple quantum coherence (HMQC)), heteronuclear multiple bond correlation (HMBC) and chemical methods. The structure of the saponins were established to be 3-O-[-D-glucopyranosyl-(1 2)--L-rhamnopyranosyl-(1 2)--L-arabinopyranosyl]-28-O-[-D-xylopyranosyl-(1 4)--L-rhamnopyranosyl-(1 3)--D-glucopyranosyl]-23-hydroxyolean-12-en-28-oic acid and 3-O-[-D-glucopyranosyl-(1 2)--L-rhamnopyranosyl-(1 2)--L-arabinopyranosyl]-28-O-[-D-glucoyranosyl-(1 3)--D-glucopyranosyl]-23-hydroxyolean-12-en-28-oic acid. Different extracts and compounds were also tested for antifilarial and antimicrobial activities. Methanolic, acetone and aqueous extracts of seeds exhibited some pronounced pharmacological activity under study.