Comparison of Antioxidant Properties of Water and Ethanol Extracts Obtained from Dried Boxthorn (Lycium chinensis) Fruit

Antioxidant activities of W and E extracts obtained from dried boxthorn (Lycium chinensis) fruit were measured based on DPPH radical scavenging and reducing powers, and their relationships with total phenolics, flavonoid content, and antioxidant activity were investigated. A linear correlation among antioxidant activity, total phenolics, and flavonoid content was observed in concentration-dependent mode. Both extracts showed >95% DPPH radical-scavenging activity and the higher reducing power of 3200 ppm at the same concentration. The antioxidant potential of both extracts were compared with those of commercial antioxidants such as BHA, BHT, TBHQ, ferulic acid, and -tocopherol using H2O2 scavenging activity, inhibition of linoleic acid peroxidation, inhibition of hemolysis of rat erythrocyte induced by peroxyl radicals, and inhibition of Fe-induced lipid peroxidation using rat brain tissue. In the H2O2 scavenging activity, E extract showed a comparable significant antioxidant power, comparable to commercial antioxidants, and no significant difference (p > 0.05) was found between W and E extracts on inhibition of the linoleic acid peroxidation. Whereas W extract exhibited a significant power in the hemolysis of rat erythrocytes, none was observed in E extract. In the Fe-induced lipid peroxidation using rat brain tissue, no significant difference (p > 0.05) was found between both extracts, showing a comparable activity with those of synthetic antioxidants. Both W and E extracts of dried boxthorn (Lycium chinensis) fruit may have a potential as natural antioxidants to replace synthetic antioxidants.