Antioxidant and free radical scavenging properties of four plant species used in traditional medicine in Lesotho

Abstract

Among the top ten causes of death in Lesotho are degenerative diseases such as heart failure, anaemia, diabetes mellitus and stroke, which are generally linked to oxidative stress. The therapeutic benefit of medicinal plants in the treatment of degenerative diseases is attributed to their antioxidant properties. In the present study, crude extracts of four plant species used in ethnomedicine in Lesotho were evaluated for their antioxidant activities using 1, 1-diphenyl-2- picrylhydrazyl (DPPH) free radical scavenging, reducing power, hydrogen peroxide scavenging and total phenolics. The species were Leucosidea sericea (leaves), Berkheya setifera (corm), Trifolium burchellianum (leaves, stems and roots) and Polygala virgata (leaves and stems). Camellia sinensis (green tea) was included as a standard as it is known to have antioxidant activity. Results showed that these plants scavenged DPPH radicals and hydrogen peroxide, reduced Fe3+ to Fe2+ and contained phenolics. A fair correlation between total phenolics and antioxidant activity was observed. L. sericea and B. setifera with the highest content of phenolics (149.63 and 66.0 mg GAE/g dry extract respectively) were also more potent in all the antioxidant assays. The results suggested that phenolics in these plants could be partly responsible for their beneficial therapeutic effects.