"Polyphenol profiles and antioxidant actvity of grape pomace extracts from Vits vinifera Sicilian cultivar"

Grape, one of the world's largest fruit crops, with more than 58 million metric tons, is cultivated mainly as Vitis vinifera for wine production. Wine-making affords grape pomace as a by-product in an estimated 13% by weight of the grapes. Italy is one of the main wine producers in the world, and wine-making in the Sicily region is on the increase. Thus, considerable amounts of grape pomace are obtained as a by-product in this area. Nevertheless, there has been no chemical study carried out on Sicilian grape pomace to date. It is known that grape pomace is a rich source of polyphenols possessing beneficial effects on human health. However, the available studies on grape pomace are relatively scarce in comparison with those carried out on wine components. Indeed, a variety of epidemiological, clinical and in vitro studies have been carried out in support of the positive role of wine polyphenols in preventing CHD (Cardiovascular Hearth Diseases), as well as in chemoprevention of cancer and other degenerative diseases associated with oxidative or inflammatory processes. These data suggest that grape pomace, if conveniently processed, could furnish crude extracts or purified products with potential health benefits. However, a significant variability in quantitative and qualitative distribution of chemical constituents in grape pomace has to be expected depending on an array of important factors, such as the varietal differences of Vitis vinifera, the location of crops and the wine-making procedures. In particular, destemming of grapes is currently used in the majority of wineries. Thus, we have carried out a chemical study on crude extracts obtained with methanol from separate samples of both destemmed grape pomace and stems. Grape pomaces of various Vitis vinifera cultivars largely employed in Sicily for wine production were analysed, namely 'Nerello Mascalese' (NM) 'Nerello Cappuccio' (NC) 'Nero d'Avola' (NA) and 'Cabernet Sauvignon' (CS). We focused our study on the main anthocyanins, flavonols and flavonols glycosides, identified and, when possible, quantified through LC-UV-DAD and LC-MS-ESI analysis of crude extracts. In addition, we have examined the crude extracts and selected fractions for antioxidant activity, in particular as radical scavenging activity towards the radicals ABTS.+ and DPPH. A comparison of the radical scavenging activity data for different cultivars, as well as the relationship with polyphenol profiles, will be presented.