Three New Triterpenoidal Saponins Acylated with Monoterpenic Acid from Albizziae Cortex

The structures of Julibrosides I, II, and III, isolated from dried stem bark of Albizzia julibrissin DURAZZ (Albizziae Cortex), were characterized as complex triterpenoidal glycosides linked to the monoterpene glycoside dimer, mainly by means of an NMR spectroscopic method. These compounds have a common structure comprising from acacic acid, the (6S)-2-trans-6-hydroxy-2,6-dimethy1-2,7-octadienoyl-6-O-quinovopyranoside dimer, and α-l-arabinofuranosyl-(1→4)-[β-d-glucopyranosyl-(1→3)]-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranoside. The diversity of the oligosaccharides attached to the C-3 hydroxyl group of acacic acid, an oleanane-type triterpene, makes a distinction between Julibrosides I, II, and III.