Synergistic Antioxidant Activity of Sweet Potato Extracts in Combination with Tea Polyphenols and Pueraria Flavonoid in Vitro

The antioxidant activity of Sweet Potato Extracts (SPE) can be enhanced by the presence of these other active antioxidants such as Tea Polyphones (TP) and Pueraria Flavonoid (PF). Since many of these natural antioxidants are consumed together in foods, the potential for synergistic interactions is high in the human diet. The aim of this study was to determine what concentrations and combinations of antioxidants among SPE, TP and PF are capable of producing synergistic antioxidant effects, based on potato-based food products. Solutions of the antioxidant activity of SPE, TP and PF, alone and in different combinations were measured using the stable free radical 2, 2-Diphenyl-1-Picrylhydrazyl (DPPH) and Ferric Reducing Anti-oxidant Power (FRAP) method. A comparison of the antioxidant activity of the combinations of antioxidants to the arithmetic sum of the antioxidant activity of the individual antioxidants was used to calculate the Synergistic Effects (SEs) between the antioxidants. The results showed that all concentrations of TP and PF combination with SPE (1 and 1.5%) could produce significant SEs (p<0.05) of DPPH and FRAP for the two or three component mixtures. With the concentration of 1% SPE,1×10-5 g/mL TP and 5×10-5 g/mL PF in the three-component mixture, the highest SE of DPPH and FRAP was both detected. The results suggested that the antioxidant property of this combination was substantially superior to the sum of the individual antioxidant effects and these interactions can enhance the antioxidant effectiveness of SPE. The results could guide in the formulation and development of functional food products that have high antioxidant potential.