DPPH radical scavenging activity of extracts from Urtica urens (Urticaceae)

In this study, hexane, chloroform, ethyl acetate and methanolic extracts from leaves, stem-bark and root of Urtica urens were evaluated for their antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. The hexane, chloroform, ethyl acetate and methanolic extracts from leaves of U. urens showed scavenging activity ranging from 7.06±2.52 to 26.01±1.84, 10.86±1.81 to 41.48±1.91, 7.53±3.21 to 51.85±4.20 and 51.50±1.97 to 73.84±6.82%,  respectively, at various concentrations. The hexane, chloroform, ethyl acetate and methanolic extracts from stem-bark of U. urens showed scavenging activity ranging from 3.26±1.84 to 38.54±2.78, 2.93±1.02 to 56.56±3.16, 19.19±1.77 to 53.99±2.18 and 30.10±0.07 to 62.80±1.90%, respectively, at various concentrations. The chloroform and methanolic extracts from root of U. urens showed scavenging activity ranging from 9.57±1.39 to 46.31±2.35 and 38.53±9.18 to 76.51±2.02%, respectively, at various concentrations. Additionally, the IC50 values of these extracts were also determined and was found to be in the range of 3000 µg/mL. The positive control, ascorbic acid, exhibited an IC50 value of <200 µg/mL. U. urensis reported to have many therapeutic applications, which include treating asthma, hearting related problems, pulmonary tuberculosis and cleansing the bladder. Basotho tribes use U. urens during spring season to increase iron content in the blood. Further studies on U. urens are required to explore this plant for its commercial applications. Key words: Urtica urens, DPPH radical scavenging assay, ascorbic acid, solvent extracts.