Triterpenoid saponins from the roots of Sophora koreensis

Abstract

From the roots of Sophora koreensis (Fabaceae), three new oleanene-type triterpene glycosides, echinosophorosides A1 (1) and B (2), and acetyl-subproside II (5), were isolated as their methyl esters, together with the four known ones sophoraflavoside I, kudzusaponin SA3, subproside II, and azukisaponin V. The structures of the new saponins were elucidated to be 3-O-α-L-rhamnopyranosyl(1→2)-α-L-arabinopyranosyl(1→2)- β-D-glucuronopyranosyl kudzusapogenol A 22-O-α-L-arabinopyranoside (1), 3-O-α-L-rhamnopyranosyl(1→2)-α-L- arabinopyranosyl(1→2)-β-D-glucuronopyranosyl abrisapogenol C 22-O-α-L-arabinopyranoside (2), and 3-O-α-L- rhamnopyranosyl(1→2)-α-L-arabinopyranosyl(1→2) -β-D-glucuronopyranosyl kudzusapogenol A 22-O-acetate (5), respectively. It is noteworthy that two arabinopyranosyl moieties in the same molecule, echinosophoroside B (2), have different conformations. The conformation of the arabinopyranosyl moiety existing in the trisaccharide moiety was determined to be 1C4, whereas that of the arabinopyranosyl unit at C-22 was identified as 4C1. © 2004 Pharmaceutical Society of Japan.