A new resin glycoside from Calystegia soldanella and its antiviral activity towards herpes

A new resin glycoside, named calysolin XVIII (1), was isolated from the leaves, stems and roots of Calystegia soldanella Roem. et Schult. (Convolvulaceae). The structure of 1 was defined as 11S-jalapinolic acid 11-O-β-d-glucopyranosyl-(1 → 3)-O-(2-O-2S-methylbutyryl,4-O-3-hydroxy-2-methylenebutyryl)-α-l-rhamnopyranosyl-(1 → 2)-[O-β-d-glucopyranosyl-(1 → 6)-O-(34-di-O-2S-methylbutyryl)-β-d-glucopyranosyl-(1 → 3)]-O-β-d-glucopyranosyl-(1 → 2)-β-d-quinovopyranoside, intramolecular 1,2″′″′-ester on the basis of spectroscopic data. Compound 1 is the first known resin glycoside to feature 3-hydroxy-2-methylenebutyric acid as a component organic acid. In addition, 1 demonstrated an antiviral activity against herpes simplex virus type 1, with an IC₅₀ value 2.3 μM.