Scavenging Evaluation of Different Free Radicals by Three Species of Ziziphus and Their Fractions

A free radical is a compound with one or more unpaired electrons in its outer orbital. Excess production of free radicals in the body is dangerous. Today, antioxidants are consumed in the food industry and cosmetics. Most of the antioxidants are manufactured synthetically. The main disadvantage of these synthetic antioxidants is their side effects. Plants are the potential sources of natural antioxidants. In the present study, we investigated the antioxidant activities of three species of Ziziphus and their fractions. In vitro, antioxidant activity was evaluated by using methods such as nitric oxide radical scavenging, hydroxyl radical scavenging and DPPH radical scavenging. For this purpose, after preparation of the crude extracts they were loaded on the resin as the stationary phase and eluted by water, water–ethanol (1:1) and ethanol, respectively. Then the different fractions were obtained. In this study, the results showed that water–ethanol fractions possessed the highest free radical scavenging. In the DPPH radical scavenging, the IC50 of water–ethanol fractions of Ziziphus jujuba, Ziziphus mauritiana and Ziziphus spina christi was 140.24 ± 2.21, 115.8 ± 1.07 and 174.34 ± 2.52 μg/ml, respectively. The IC50 of quercetin as a standard was 61.4 ± 0.98 μg/ml. In nitric oxide radical scavenging, the crude extract of Z. mauritiana showed the highest antioxidant activity (IC50 = 143 ± 9.3 μg/ml). The water–ethanol fractions of all the samples exhibited the greatest hydroxyl radical inhibition at concentration of 1 mg/ml.