Novel dammarane triterpenoid glycosides from the leaves of Hovenia dulcis. X-Ray crystal structure of hovenolactone monohydrate

Abstract

Saponin E, isolated from the leaves of Hoevenia dulcis, afforded a new dammarane triterpene aglycone, hovenolactone, on treatment with naringinase. The structure of hovenolactone, including the relative configurations at C-17, C-20, and C-23, was established by chemical and spectroscopic investigations as well as by X-ray analysis. Saponins E and H were separated by droplet counter-current chromatography. The complete molecular configurations of both glycosides were determined to be 3-O-(2-O-α-L-rhamnopyranosyl-β-D-glucopyranosyl)hovenolactone and 3-O-β-D-glucopyranosylhovenolactone, respectively, by ¹³C n.m.r. spectroscopy.