Free radical scavenging and total antioxidant capacity of methanol extract of ethulia conyzoides growing in nigeria

Antioxidant activity of methanol extract of Ethulia conyzoides was evaluated using the free radical scavenging activity of the 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH), total antioxidant capacity (TAC) of the phosphomolybdenum method and the estimation of total phenolics content. The percent (%) scavenging (antioxidant) activity indicate a concentration dependent activity with no significant difference from the activity of standard Gallic acid (P<0.05) except at 31.25μgml. The total antioxidant capacity which is a measure of both water-soluble and fat-soluble antioxidants showed a similar concentration dependent fashion (in mg/g Ascorbic acid equivalent). The total phenolics content was found to be 425 mg/100g of Gallic acid equivalent on a fresh weight basis. The effective concentration (EC50) sufficient to elicit 50% of a maximum effect estimated in 100 % was calculated to be 46.16±1.52μg/ml for the DPPH radical scavenging activity. The Phytochemical screening revealed the presence of tannins and flavonoids whose synergistic effects may be responsible for the high antioxidant activity. Correlation analysis between the values of DPPH and TAC (r2=0.7790) indicates the viability of the two models for evaluating antioxidants from medicinal plants. Our findings revealed that methanol extract of E. conyzoides possess interesting antioxidant activity, which may provide protection against free radicals induced damage to biomolecules. © 2012 University of Bucharest.