Antiradical activity of phenolic metabolites extracted from grapes of white and red Vitis vinifera L. cultivars

A diet rich in plant foods is strongly recommended for its beneficial effect on human health. In fact, plant secondary metabolites may exert various biological activities on mammalian cells. Among them, phenolics are excellent natural antioxidants able to rescue cell redox unbalance responsible for the onset of different pathologies. For these reasons, the present work was focused on the study of grape extracts obtained from eight different Italian Vitis vinifera cultivars, quite rare in Italian viticulture and not yet completely chemically characterized. For each preparation, total simple phenolic, flavonoidic and anthocyaninic content was measured through spectrophotometrical assays, while detailed biochemical profile was revealed by LC-MS analyses. In order to valorize the products of these varieties and increase our knowledge about their potential healthy role, the antioxidant power of the samples was evaluated by two different in vitro antiradical tests: DPPH and FRAP. Moreover, free radical scavenging properties of eleven grape pure compounds were investigated, with the aim to: a) compare their real antiradical property with the theoretical one; b) identify which one of them possessed the best bioactivity; c) understand how they might singularly contribute to the nutraceutical effect of the whole grapevine phytocomplex.