Evaluating the antioxidant activity of different plant extracts and herbal formulations

Aqueous extracts of different medicinal plants, viz., Momardica charantia Linn (E1), Glycyrrhiza glabra (E2), Acacia catechu (E3), Terminalia bellerica (E4), Terminalia chebula (E5) and Emblica officinalis (E6), and a combination drug, Triphala (E7), containing equal amounts of E4, E5 and E6, has been evaluated for the antioxidant activity. The methods employed include γ-radiation induced lipid peroxidation in rat liver microsomes and strand breaks in plasmid DNA. Factors responsible for such activity were examined by phtytochemical analysis and radical scavenging abilities of different extracts. Using pulse radiolysis total antioxidant activities of these extracts were determined and expressed in terms of ascobate equivalents. A good correlation was obtained between antioxidant activity and antioxidant equivalents. The antioxidant activities of the extracts were found to vary as follows: E1 and E2 did not show any antioxidant activity and have very low ascorbate equivalents. E3 acts as a moderate antioxidant, while E4, E5, E6 and E7 are very good antioxidants and are rich in phytochemicals which have high antiradical activity properties.