Isolation of Two Novel Terpenoid Glucose Esters from Riesling Wine

Abstract

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 wine constituents. The identification was achieved by mass spectrometry (DCI-MS) as well as nuclear magnetic resonance spectroscopy (1H NMR, 13C 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(3H)-one (wine lactone) was formed, thus revealing an important aroma precursor function for glucoconjugate 1. Keywords: (E)-2,6-Dimethyl-6-hydroxyocta-2,7-dienoic acid glucose ester; (2E,6E)-10,11-dihydroxy-3,7,11-trimethyl-2,6-dodecadienoic acid glucose ester; aroma precursor; wine lactone; multilay...