The antioxidant activity of some medicinal plants

The antioxidant properties of the methanol extracts of 10 medicinal plants were evaluated with the DPPH (1,1-diphenyl-2-picryl hydrazyl) test, hydroxyl scavenging test, and lipid peroxidation assay. The methanol extract of Emblica officinalis was the most active according to the DPPH test, with an IC50 value of 7.92 +/- 0.1 mu g/ml, followed by Asparagus racemosus, with an IC50 value of 9.28 +/- 0.2 mu g/ml. The minimum free radical scavenging activity was shown by Zingiber officinale, with an IC50 value of 44.48 +/- 1.8 mu g/ml. The hydroxyl radical scavenging activity of the methanolic extracts of various plants was as follows: Asparagus racemosus > Terminalia chebula > Emblica officinalis > Centella asiatica > Withania somnifera > Terminalia bellerica > Glycyrrhiza glabra > Evolvulus alsinoides > Zingiber officinale > Andrographis paniculata. According to the lipid peroxidation assay the extracts of Emblica officinalis and Evolvulus alsinoides showed the greatest effectiveness, with inhibition values of 39.14 +/- 2.1 % and 36.38 +/- 1.3%, respectively, at the 100-mu g/m concentration (P < 0.05). Results of the present study suggest that all the tested plant materials had moderate to potent antioxidant activity.