Scropolioside-D₂ and Harpagoside-B: Two New Iridoid Glycosides from Scrophularia deserti and Their Antidiabetic and Antiinflammatory Activity

Abstract

Five iridoid glycosides, including the two new compounds scropolioside-D₂ (1) and harpagoside-B (2), were isolated from the aerial parts of Scrophularia deserti DEL (Scrophulariaceae). Their structures were elucidated on the basis of spectral data to be 6-O-[2″,4″-di-O-acetyl-3″-O-trans-cinnamoyl)-α-L-rhamnopyranosyl]-8α-hydroxymethyl-1α,5β,6α,7α,9β-pentahydro-7(8)-epoxy-2-oxaind-3-ene-1-O-β-D-glucopyranoside-6′-O-acetate (1) and 5-O-β-hydroxy-8-O-β-trans-cinnamoyl-8α-methyl-1,6,7,9-tetrahydro-2-oxaind-3-ene-1-O-β-D-glucopyranoside (2), respectively. In addition, three more iridoid glycosides, scropolioside-D (3), koelzioside (4), and 8-O-acetyl-harpagide (5), were also isolated and characterized from this source. The biological activity and the structure activity relationship of the compounds were also studied, and scropolioside-D (3) and harpagoside-B (2) were found to possess significant antidiabetic and antiinflammatory activity, respectively.