Evaluation of the antioxidant activity of the extracts The in vitro antioxidant activity of the extracts was determined using a DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical scavenging assay according to the method described in previous publication [34]. The stock solution of extract was diluted to prepare a series of concentrations (50, 100, 200, 400 and 800 μg/ml) for the antioxidant assay. An aliquot of 1.5 ml of 0.25 mM DPPH solution in ethanol and 1.5 ml of extract at each of the various concentrations was mixed. The mixture was shaken vigorously and allowed to sit for 30 min reach a steady state at room temperature. The decolourization of DPPH was determined by measuring the absorbance at 517 nm using a Genesys UV-visible spectrophotometer. The percentage of DPPH freeradical scavenging activity of each extract was then calculated using the following equation: