A new resin glycoside from <i>Calystegia soldanella</i> and its antiviral activity towards herpes

<p>A new resin glycoside, named calysolin XVIII (<b>1</b>), was isolated from the leaves, stems and roots of <i>Calystegia soldanella</i> Roem. et Schult. (Convolvulaceae). The structure of <b>1</b> was defined as 11<i>S</i>-jalapinolic acid 11-<i>O</i>-β-d-glucopyranosyl-(1 → 3)-<i>O</i>-(2-<i>O</i>-2<i>S</i>-methylbutyryl,4-<i>O</i>-3-hydroxy-2-methylenebutyryl)-α-l-rhamnopyranosyl-(1 → 2)-[<i>O</i>-β-d-glucopyranosyl-(1 → 6)-<i>O</i>-(34-di-<i>O</i>-2<i>S</i>-methylbutyryl)-β-d-glucopyranosyl-(1 → 3)]-<i>O</i>-β-d-glucopyranosyl-(1 → 2)-β-d-quinovopyranoside, intramolecular 1,2″′″′-ester on the basis of spectroscopic data. Compound <b>1</b> is the first known resin glycoside to feature 3-hydroxy-2-methylenebutyric acid as a component organic acid. In addition, <b>1</b> demonstrated an antiviral activity against herpes simplex virus type 1, with an IC<sub>50</sub> value 2.3 μM.</p>