Iridoid Glucosides from Penstemon nitidus

Abstract

From the leaves of Penstemon nitidus Dougl. (smooth blue beardtongue) besides the known iridoid glucosides cornin (syn. verbenalin), hastatoside and β-dihydrohastatoside the new compound 10-hydroxycornin has been isolated. The structures of all compounds were established by spectroscopic means (FD-MS, ¹H-, ¹³C-, 2D-NMR, and NOE). This is the first report of cornin and analogous 6-keto iridoids in scrophulariaceous plants. Up to now iridoid glucosides like these have only been found in plants belonging to the Cornaceae and its allies and to the Lamiaceae-Verbenaceae complex.

Key words

Penstemon nitidus - Scrophulariaceae - iridoid glucosides - cornin - hastatoside - β-dihydrohastatoside - 10-hydroxycornin - structure elucidation