Structures of eremophilane-type sesquiterpene glucosides, alticolosides A-G, from the Far Eastern endemic Ligularia alticola Worosch

Abstract

Seven eremophilane-type sesquiterpene glucosides, alticolosides A-G, have been isolated from aerial parts of the endemic Far Eastern species Ligularia alticola Worosch. (Family Asteraceae) along with two known compounds, monoterpenoid glycoside (4S)-α-terpineol 8-O-β-D-glucopyranoside and norditerpenoid glycoside 7(8)-dihydro-β-ionone 3-O-β-D-glucopyranoside. Alticoloside D was identified with the earlier known 8-O-(β-D-glucopyranosyl)-2-oxo-eremophila-1(10),8,11-triene, but the stereostructure of the latter was revised on the basis of ROESY and CD data. All the glycosides are derivatives of new eremophilane-type aglycones, differing from known eremophilanes in details of planar and/or stereo structures except for the aglycone of alticoloside E.

Keywords: Alticolosides; Ligularia alticola; NMR; Sesquiterpene eremophilane-type glycosides.