Studies on the Constituents of Actinostemma lobatum MAXIM. VI. Structures of Lobatosides I, J and K, Oleanolic Acid and Gypsogenin Glycosides Isolated from the Seed

Abstract

Two new gypsogenin glycosides, named lobatosides I and J, and one oleanolic acid glycoside, lobatoside K, were isolated from the seed of Actinostemma lobatum MAXIM. (Cucurbitaceae), and thier structures were elucidated to be as follows based on chemical and spectral evidence.Lobatoside I : 3-O-[O-β-D-galactopyranosyl-(1→2)-β-D-glucopyranosyluronic acid]gypsogenin 28-{O-β-D-glucopyranosyl-(1→3)-[O-β-D-xylopyranosyl-(1→4)]-O-α-L-rhamnopyranosyl-(1→2)-β-D-fucopyranosyl}ester.Lobatoside J : 3-O-[O-β-D-galactopyranosyl-(1→2)-β-D-glucopyranosyluronic acid]gypsogenin 28-{O-β-D-xylopyranosyl-(1→3)-O-β-D-xylopyranosyl-(1→4)-[O-β-D-glucopyranosyl-(1→3)]-O-α-L-rhamnopyranosyl-(1→2)-β-D-fucopyranosyl}ester.Lobatoside K is an oleanolic acid glycoside. The structure of the sugar moiety is the same as that of lobatoside I.