Antiradical potential of ancient Italian apple varieties of Malus × domestica Borkh. in a peroxynitrite-induced oxidative process

Ancient apple cultivars may be an important source of genes for apple breeding programs and for the production of value-added apple cultivars. We evaluated the biochemical properties of six apple varieties grown in the Casentino area (Tuscany, Italy). Two commercial varieties (Golden Delicious and Stark Delicious) and four local varieties (Mora, Nesta, Panaia-red and Ruggine) were selected and their methanolic extracts were analysed for total phenolics and flavonoids. Moreover the content of catechin, epicatechin, rutin, chlorogenic and caffeic acid, five major phenolic constituents, was determined through HPLC-UV analysis. The radical scavenging capacity of the methanolic extracts was assessed using two in vitro tests: the blanching of the stable DPPH radical and the inhibition of tyrosine nitration induced by peroxynitrite. Three of the four local varieties had the highest content of total phenols and flavonoids. Ruggine and Panaia-red apple had the highest content of the five phenolic compounds investigated and the highest antioxidant activity towards both radicals. The commercial varieties were characterized by lower phenolic content and antioxidant activity compared to old varieties. Finally, a significant correlation between phenolic content and antioxidant activity was found.