Comparison of microwave assisted and traditional extraction of Urtica dioica L. and evaluation of its antioxidant activity by HPLC- DPPH assay

In the present study, the effects of two types of extraction traditional and microwave-assisted extraction (MAE) on antioxidant activity of Urtica dioica L. was investigated. Water, methanol and ethanol extracts of leaf and stem of Urtica dioica L. were obtained from both traditional and MAE methods and evaluated for their radical scavenging capacity (RSC) by high performance liquid chromatography (HPLC)-separated antioxidants with the 2,2‘-diphenyl-1-picrylhydrazyl radicals (DPPH•). The antioxidant activities of all the extracts were determined by high performance liquid chromatography at 517nm using 1, 1-diphenyl-2-picrylhydrazyl free radical (DPPH). It was determined that antioxidant activity of leaf and stem (ethanol extracts) of Urtica dioica L. by MAE method was higher compared to traditional method, however, was not significantly different (p>0.05). In conclusion, HPLC-DPPH assay did not show significant difference between MAE and traditional methods in antioxidant activity of leaf and stem of Urtica dioica L.