Valorization of three varieties of grape

In the present investigation, seed methanolic extracts of three Vitis vinifera (Muscat d'Italie, Syrah and Carignan) were assayed for their antioxidant activities. Results showed that there are strong variations in the contents of total phenols (440.97-121.94 mg GAE g(-1) DW), flavonoids (48.07-16.81 mg EC g(-1) DW) and tanins (37.15-14.9 mg EC g(-1) DW) from the studied seeds. The phenolic composition of these extracts was determined by RP-HPLC after acid hydrolysis. The main phenolic compound was quercetin with 27.2% in Muscat d'Italie, 48.8% in Syrah and 28.4% in Carignan. Besides, all seed extracts showed remarkable DPPH radical scavenging activity with IC50 values ranged from 1.8 to 30 mu g ml(-1). EC50 values of reducing power activity ranged from 100 to 120 mu g ml(-1). The high phenolic content and the considerable antioxidant activities of vitis seed extracts could potentially be considered as an expensive source of natural antioxidants. (C) 2009 Elsevier B.V. All rights reserved.