In vitro antioxidant activity of Enicostemma axillare

Four successive extracts of the whole plant of Enicostennna axillare (E. axillare), were examined for in vitro antioxidam activity using nine different methods. In the 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) method, all the four extracts of E. axillare showed potent antioxidant activity with IC50 values ranging from 13.26 to 24.36 mu g/ml. The chloroform extract has shown potent antioxidant activity in H2O2, nitric oxide, and hydroxyl radical using the deoxyribose and lipid peroxidation methods, with IC50 values of 16.99 +/- 0.38, 60.66 +/- 0.30, 25.06 +/- 0.12, and 94.66 +/- 2.40 mu g/ml, respectively. Potent activity was also observed for the petroleum ether extract with the deoxyribose, p-nitroso dimethyl aniline (p-NDA), and H2O2 methods and for the ethyl acetate extract with the H2O2 and nitric oxide methods. All extracts showed moderate total antioxidant capacity using the phosphomolybdenum method. The activity was not correlated with the total phenol content of the extracts.