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 (2 E,6 E )-10,11-dihydroxy-3,7,11-trimethyl-2,6-dodecadienoic acid ( 2 ) were identified for the first time as wine constituents. The identification was achieved by mass spectrometry (DCI-MS) as well as nuclear magnetic resonance spectroscopy ( 1 H NMR, 13 C NMR, COSY, HMBC). In biomimetic studies carried out with ( E )-2,6-dimethyl-6-hydroxyocta-2,7-dienoic acid the potent wine aroma compound 3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3 H )-one (wine lactone) was formed, thus revealing an important aroma precursor function for glucoconjugate 1 .