Intracellular Reactive Oxygen Species (ROS) Removal and Cytoprotection Effects of Sweet Potatoes of Various Flesh Colors and Their Polyphenols, Including Anthocyanin

The flesh color of sweet potatoes varies based on the antioxidant pigments in the cultivar. In this study, the antioxidant characteristics of various flesh color sweet potato cultivars (Jinyulmi, Juhwangmi, Pungwonmi, and Sinjami) were investigated. The polyphenol contents were highest in the purple-fleshed cultivar, Sinjami (39, 68, and 71 μg gallic acid equivalent/g in distilled water, fermented ethanol, and ethanol extracts, respectively). The Sinjami cultivar contained 29 mg/100 g of anthocyanin, which is the major component resulting in increased concentrations of polyphenols. Using 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid), 2,2-diphenyl-1-picrylhydrazyl, and ferric reducing ability of plasma assays, Sinjami showed greater antioxidant activity than the other cultivars. Additionally, the Sinjami extracts could recover cellular reactive oxygen species levels in tert-butyl hydroperoxide-stimulated HepG2 cells to a normal level. In conclusion, anthocyanin-enriched Sinjami has strong antioxidant activities and could improve health by suppressing oxidative damage.