Study of three new p-coumaroyl glycoside flavonoids in some Italian red grape varieties

Main flavonols in grape are myricetin, quercetin and kaempferol present in glucoside and\r\nglucuronide forms [1]. Recently, also laricitrin, isorhamnetin and syringetin glucoside,\r\ngalactoside and glucuronide were found [2]. In general, they are antioxidant compounds\r\ncontained in dietary plants used for human nutrition [3].\r\nA “suspect screening analysis” method by high-resolution mass spectrometry to study grape\r\nmetabolomics was developed [4]. By this approach, three new p-coumaroyl flavonoids were\r\nputatively identified in Raboso Piave grape extract. Compounds were identified by overlapping\r\nvarious analytical methods according to recommendations in the MS-based metabolomics:\r\naccurate mass measurement provided the structural characterization of functional groups and\r\nliterature data their probable position in the molecule. Compounds identified are a\r\ndihydrokaempferide-3-O-p-coumaroylhexoside-like flavanone, isorhamnetin-3-O-pcoumaroylglucoside,\r\nand a chrysoeriol-p-coumaroylhexoside-like flavone (Figure 1) [5].\r\nIn the present work, the study of these compounds was extended to other red grape varieties to\r\nevaluate their use as varietal markers. Correlation between p-coumaroyl derivatives and the\r\nanthocyanins was also studied to investigate the existence of possible common biosynthetic\r\npathways.