Antioxidant compounds and antioxidant activity in "early potatoes".

The antioxidant content and the antioxidant capacity of both hydrophilic and lipophilic antioxidant extracts from four "early potato" cultivars, grown in two different locations (Racale and Monteroni), were examined. There was a considerable variation in carotenoid content and weak differences in the ascorbic acid concentration of the examined cultivars of "early potato" and between the harvested locations. An increase in both methanol/water (8:2 v/v) and phosphate buffer soluble (PBS) free phenols (70%) and bound phenols (28%) in the extracts from the cultivars grown at Racale site was found and discussed. Examination of individual phenols revealed that chlorogenic acid and catechin were the major phenols present in potato tuber extracts; a moderate amount of caffeic acid and ferulic acid was also detected. The total equivalent antioxidant capacity (TEAC) was higher in the Racale extracts and a highly positive linear relationship ( R (2) = 0.8193) between TEAC values and total phenolic content was observed. The oxyradical scavenging capacity (TOSC) of methanol/water and PBS extracts of peel and whole potatoes against the reactive oxygen species (ROS) peroxyl radicals, peroxynitrite, and hydroxyl radicals was also analyzed. A highly significant linear correlation ( R (2) = 0.9613) between total antioxidant capacity (as a sum of peroxyl radicals + peroxynitrite) and total phenol content of methanol/water extracts was established. Moreover, proliferation of human mammalian cancer (MCF-7) cells was significantly inhibited in a dose-dependent manner after exposure to potato extracts. These data can be useful for "early potato" tuber characterization and suggest that the "early potato" has a potential as a dietary source of antioxidants.