GLYCOSIDICALLY BOUND NORISOPRENOIDS FROM VITIS-VINIFERA CV RIESLING LEAVES

HRGC and HRGC-MS identifications of glycosidically bound Riesling leaf constituents were achieved after extraction with MeOH, Amberlite XAD-2 adsorption, and subsequent enzymatic hydrolysis of the glycoconjugates. Among the enzymatically liberated aglycons 23 bound C-13 norisoprenoids were identified. With the aid of multilayer coil countercurrent chromatography (MLCCC) five major C-13 glycosides were purified, and their structures were elucidated by high-field NMR, i.e., the beta-D-glucopyranosides of vomifoliol, 4,5-dihydrovomifoliol, 3-hydroxy-5,6-epoxy-beta-ionone, grasshopper ketone, and 3-oxo-megastigman-9-ol. The latter glucoside with a saturated megastigmane skeleton is reported here for the first time. In addition, the P-D-glucopyranosides of benzyl alcohol and raspberry ketone have been isolated.