Extraction, Purification and Characterization of Antioxidant Fractions from Zizyphus spina-christi Fruits

In this study, in vitro antioxidant activity, total phenolic content and concentration of flavonoids of five different extracts from the Zizyphus spina- christi fruits were determined using spectrophotometric methods. Antioxidant activity of extracts were expressed as percentage of DPPH radical inhibition and values were ranged from 31.76% - 90.23% which indicated that zizyphus manifested the strongest capacity for neutralization of DPPH radicals. The total phenolic content ranged from 11.04 - 56.44 mg/g expressed as quercitin equivalent. The concentration of flavonoids in the zizyphus extracts varied from 16.66 - 58.32 mg/g expressed in terms of rutin equivalent (mg of RU/g extract). Methanolic extract of zizyphus showed the highest phenolic and flavonoid concentration and strong antioxidant activity. The significant linear correlation was confirmed between the values for the total phenolic content and antioxidant activity of plant extracts. The high contents of phenolic compounds indicated that these compounds contribute to the antioxidant activity. The zizyphus fruit can be regarded as a promising candidates for natural plant sources of antioxidant with high value.