Antioxidant and Free Radical Scavenging Properties of Traditionally Used Three Indian Medicinal Plants

The antioxidant properties of methanol extract of three medicinal plants viz. Withania somnifera, Asparagus racemosus and Centella asiatica that probably involve free radical mechanisms, were evaluated by the methods, namely the ABTS (2, 2’-azinobis-3-ethylbenzothiozoline-6-sulphonic acid) radical scavenging assay, Trolox equivalent antioxidant capacity assay (TEAC), Oxygen radical absorbance capacity (ORAC) assay, DPPH free radical scavenging activity assay, Super oxide scavenging activity assay and Nitric oxide radical scavenging activity assay. The methanol extract from Centella asiatica was most active in the ABTS assay with an IC₅₀ value of 185.18 μg/mL followed by Withania somnifera with IC₅₀ value of 214.78 μg/mL. The minimum activity showed by Asparagus racemosus with IC₅₀ value of 384.55 μg/mL. The Trolox equivalent antioxidant capacity, DPPH (1, 1-diphenyl-2-picryl hydrazyl) and Superoxide radical scavenging activity of the methanolic extracts was in order of Withania somnifera > Centella asiatica > Asparagus racemosus. In the Oxygen radical absorbance capacity assay the ORAC value of Withania somnifera was found maximum 443.5 μ moles TE^#/g and followed by Centella asiatica and Asparagus racemosus showed 211.5 μ moles TE^#/g and 31.3 μ moles TE^#/g respectively. The Nitric oxide radical activity was found in order of Asparagus racemosus >Withania somnifera > Centella asiatica. The present studies suggest that all the tested plants have moderate to potent antioxidant activity.