Antioxidant activities of chestnut nut of Castanea sativa Mill. (cultivar 'Judia') as function of origin ecosystem

The antioxidant properties of different ecotypes of chestnut nut (cv. Judia) were studied. Total phenolics and flavonoids were also determinated. Total phenolics amount ranged from 9.6mg/g of GAE (hottest ecotype, Murça) to 19.4mg/g of GAE (coldest ecotype, Valpaços). Gallic and ellagic acid were the predominant compounds and Valpaços had the highest values while, Murça had the lowest ones. The antioxidant capacity of ethanolic extracts were evaluated through several biochemical essays: ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity, FRAP (ferric reducing/antioxidant power) and inhibition of oxidative haemolysis in erythrocytes. In order to evaluate the antioxidant efficiency of each ecotype, the EC50 values were calculated. Once again Valpaços revealed the best antioxidant properties, presenting much lower EC50 values. Climatic conditions influence seems to be a limiting factor for production of phenolic compounds and consequently for the antioxidant properties of chestnut nuts.