Antioxidant Activity of Free and Bound Polyphenols from Pomegranate Flowers

To analyze the antioxidant activities of free polyphenolics and bound polyphenolics from pomegranate flowers, two crude polyphenolic extracts were prepared. The total phenolic contents of the crude extracts were determined by Folin-Ciocalteu method and the antioxidant activities were determined by five in vitro antioxidant methods. Results showed that the total phenolic content of the free polyphenolic extract was significantly higher than that of the bound part(P<0.05). Results from the oxygen radical absorbance capacity(ORAC) and peroxyl radical scavenging capacity(PSC) showed that two polyphenolic extracts, similar to Trolox, had an obvious character of fluorescence kinetics and a dose-dependent tendency; the antioxidant capacity of free polyphenolic extract was stronger than the bound part(P<0.05). The free polyphenolic extract had better DPPH radical scavenging activity(DRSA), trolox equivalent antioxidant capacity(TEAC), and reducing power(RP) than the bound part(P<0.05), but the antioxidant capacities of two extracts was significantly lower than vitamin C(P<0.05). Both of the extracts from pomegranate flowers had certain antioxidant activity. Moreover, compared with the bound part, the free polyphenolic extract had better antioxidant activities. The current study could provide a theoretical basis for the development and utilization of natural antioxidant.