An acylated triterpenoid saponin from Quillaja saponaria

Abstract

A new major component in the acylated triterpenoid saponin mixture (called quillajasaponin) obtained from the bark of Quillaja saponaria was isolated in a pure state. It was characterized on the basis of chemical and spectral data as 3-O-β-d-galactopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 3)]-β-d-glucuronopyranosyl quillaic acid 28-O-β-d-apiofuranosyl- (1 → 3)-β-d-xylopyranosyl- (1 → 4)-[β-d-glucopyranosyl- (1 → 3)]-α-l-rhamnopyranosyl-(1 → 2)-3-[5-O-[5-O-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinofuranosyl-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoyl]-β-d-fucopyranoside. The diazomethane cleavage method providing selectively 28-O- glycoside from 3,28-O-bisglycoside was effective for the structure elucidation. Negative fast atom bombardment mass spectrometry was useful in providing information on the molecular weight and the structure of the complex acylated oligoglycoside.