In vitro antioxidant and free radical scavenging activity of four Alkanna species growing in Iran

Abstract

Medicinal plants are recognized as sources of natural antioxidants that can protect biological system from oxidative stress. In this study, the antioxidant activities of four species of the Alkanna genus (Alkanna bracteosa, Alkanna frigida, Alkanna orientalis and Alkanna tricophila) were evaluated. The dried roots of plant samples (100 g) were extracted separately by percolation method with MeOH/H2O (80/20) and four fractions were provided respectively with hexane, chloroform, ethyl acetate, butanol and water. Antioxidant activities were investigated by using 1,1-diphenyl-2-picrylhydrazyl, ferric thiocyanate and thiobarbituric acid methods and compared with quercetin (as positive control). The results indicated that the butanol fractions of four species had the highest antioxidant activity and radical scavenging activity compared with the other fractions studied (P 0.05) between the total antioxidant activities of same fractions. The total antioxidant activity values of Alkanna fractions in a descending order are as follows: Butanol fraction > ethyl acetate fraction > total extract > hexane fraction > chloroform fraction > aqueous fraction. The antioxidant activities of butanol fractions of samples were higher than quercetin. This may be because most of the active compounds of Alkanna species dissolved in the butanol.

Keywords: 1; 1-diphenyl-2-picrylhydrazyl; Alkanna; antioxidant activity; ferric thiocyanate; thiobarbituric acid