INVESTIGATION OF ANTIOXIDANT POTENTIAL OF AN ETHANOLIC EXTRACT OF WHOLE PLANT OF LEONOTIS NEPETIFOLIA (L). R.BR.

K. Vasuki*, R. Senthamarai and P.Sudhakar

ABSTRACT

In this study antioxidant activity was performed by hydroxyl radicals, DPPH and nitric oxide radical scavenging method for an ethanolic extract of whole plant of Leonotis nepetifolia (L). R.Br. An extract was used at different concentrations like 1.25, 2.5, 5.0, 10.0, 20.0 μg/ml and radical scavenging activity was determined in terms of percentage inhibition and IC50 values were calculated. The study proved that an ethanolic extract of Leonotis nepetifolia found to have highest antioxidant activity against nitric oxide radical (% inhibition = 77.07 ± 1.77; IC50 = 2.03 μg/ml) and moderate activity against DPPH radicals (% inhibition = 64.47 ± 1.42; IC50 = 3.07 μg/ml) and minimum activity against hydroxyl radicals (% inhibition = 62.96 ± 1.78; IC50 = 7.55 μg/ml) at concentration of 20 μg/ml. The strongest antioxidant activity of an ethanolic extract may be due to the presence of flavonoids. The further study has to be focused on isolation and characterization of functional molecules of the extract and their individual activity.

Keywords: Leonotis nepetifolia (L). R.Br., in vitro antioxidant activity, free radicals.