A pseudoguaiane sesquiterpene xylopyranoside from Echinops hussoni.

A new pseudoguaiane sesquiterpene xylopyranoside ester, named echusoside (1), was isolated from the aerial parts of Echinops hussoni Boiss. (Asteraceae) collected from the southeastern border of Egypt. The structure elucidation of echusoside was based primarily on 1D, 2D-NMR analyses and chemical derivatization. This is the first report for a pseudoguainane sesquiterpene in the genus Echinops.