Study of grape bioactive stilbenes by suspect screening metabolomics

Stilbenes are one of the main classes of grape polyphenols associated with the beneficial effects of drinking wine. In the present study, a "suspect screening" metabolomics approach was used to study these grape compounds. Analysis was performed by Ultra High Performance Liquid Chromatography/Quadrupole Time-Of-Flight (UHPLC/QTOF) mass spectrometry and compounds were identified using the database GrapeMetabolomics expressly constructed. By this approach, a total of 18 stilbene derivatives was identified in two V. vinifera red grape varieties (cvs. Raboso Piave and Primitivo) on the basis of accurate mass measurements and isotopic patterns. Identifications were confirmed by multiple mass spectrometry (MS/MS). Bioactive stilbenes such as trans-resveratrol, Z- and E-piceid, piceatannol and Z- and E-astringin, and several resveratrol dimers, trimers and tetramers such as pallidol and pallidol-3-O-glucoside, E- and Z--viniferin, E- and Z-δ-viniferin, caraphenol B, parthenocissin A, E- and Z-miyabenol C, hopheapenol, ampelopsin H, vaticanol C-like or isohopeaphenol, were identified. In our knowledge, some of these resveratrol trimers and tetramers were reported in grape for the first time.