Structures of Acetylated Oleanane-Type Triterpene Saponins, Rarasaponins IV, V, and VI, and Anti-hyperlipidemic Constituents from the Pericarps of Sapindus rarak

The methanolic extract and its saponin fraction (methanol-eluted fraction) of the pericarps of Sapindus rarak DC. were found to suppress plasma triglyceride elevation in olive oil-treated mice. From the active fraction, three new acylated oleanane-type triterpene saponins, rarasaponins IV (1), V (2), and VI (3), were isolated. The structures of 1-3 were elucidated on the basis of chemical and spectroscopic evidence. The principle saponin constituents, hederagenin 3-O-alpha-L-arabinopyranosyl-(1 -> 3)-alpha-L-rhamnopyranosyl-(1 -> 2)-alpha-L-arabinopyranoside (4) and hederagenin 3-O-(3,4-di-O-acetyl-alpha-L-arabinopyranosyl)-(1 -> 3)-alpha-L-rhamnopyranosyl-(1 -> 2)-alpha-L-arabinopyranoside (5), showed inhibitory effects on plasma triglyceride elevation at a dose of 200 mg/kg, per os.