Isolation of two novel terpenoid glucose esters from Riesling wine

A glycosidic isolate of Riesling wine was separated with multilayer coil countercurrent chromatography (MLCCC). After acetylation and subsequent purification by high-performance liquid chromatography (HPLC), the glucose esters of (E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoic acid (1) and (2E,6E)-10,11-dihydroxy-3,7,11-trimethyl-2,6-dodecadienoic acid (2) were identified for the first time as nine constituents. The identification was achieved by mass spectrometry (DCI-MS) as well as nuclear magnetic resonance spectroscopy (H-1 NMR, C-13 NMR, COSY, HMBC). In biomimetic studies carried out with (E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoic acid the potent nine aroma compound 3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3H)-one (wine lactone) was formed, thus revealing an important aroma precursor function for glucoconjugate 1.