Pensteminoside, an unusual catalpol-type iridoid from Penstemon gentianoides HBK (Plantaginaceae).

From the MeOH and ethyl acetate extracts of aerial parts of Penstemon gentianoides HBK (Plantaginaceae) an unusual iridoid of the catalpol-type, was isolated and characterized as pensteminoside: (8-O-trans-cinnamoyl, 6-hydroxy, 1-[beta-D-glucopyranoside-6'-O-((4''-hydroxy)-cinnamoyl)]-catalpol) was isolated, along with the known iridoids: plantarelanoside and globularisicin, the flavone: luteolin and diosmetin, as well the phenylpropanoids, verbascoside and martynoside. Their structures were established by 1D and 2D NMR spectroscopic analyses.