Calysolins V–IX, Resin Glycosides from Calystegia soldanella and Their Antiviral Activity toward Herpes

Five new resin glycosides having macrolactone structures (jalapins), named calysolins V-IX (1-5), were isolated from the leaves, stems, and roots of Calystegia soldanella ROEM. et SCHULT. (Convolvulaceae). Their structures were determined on the basis of spectroscopic data as well as chemical evidence. The isolated compounds could be classified into two macrolactone types-one having a 22-membered ring (1-4) and the other with a 27-membered ring (5). The sugar moieties of 1-5 were found to exist in partially acylated forms comprising 2S-methylbutyric acid and tiglic acid. Compounds 4 and 5 are the first representatives of the calysolic acid C as the component glycosidic acid. Additionally, the antiviral activity of 1-5, together with calysolins I-IV and soldanelline B, which are previously isolated jalapins from this plant, toward herpes simplex virus type 1 was evaluated. All the compounds showed antiviral activity.