Antioxidant capacity and α-glucosidase inhibitory activity in peel and flesh of blueberry (Vaccinium spp.) cultivars

This study was designed to evaluate cultivar variations in phenolic content, anthocyanin content, and antioxidant activity of peel and flesh; and to determine their potential inhibitory effects on α-glucosidase in 33 blueberry (Vaccinium species) cultivars, including 29 rabbiteye (Vaccinium ashei Reade) blueberries, two V. ashei hybrid derivatives, and two northern highbush (Vaccinium corymbosum L.). The relation of phenolic, anthocyanin, and antioxidant activity to α-glucosidase inhibition in blueberries also was investigated. It was found that peel tissue possessed higher levels of total anthocyanins (TA), total phenolics (TP), antioxidant capacity, and α-glucosidase inhibitory activity than flesh tissue in all blueberries tested. The percentage contributions of peel to whole berry on scavenging capacity against peroxyl free radicals (ROO), hydroxyl radicals (OH), hydrogen peroxide (H2O2), and singlet oxygen (1O2) radicals, were higher than those of flesh, even though the fruit contained much higher amounts of flesh than peel in terms of dry weight. Cultivars with high levels of phenolic compounds, antioxidant capacities, and α-glucosidase inhibitory activities could be selected for use in blueberry breeding programs to develop new lines with improved health benefits.