Total antioxidant activity of crude extracts was determined according to the method of Prieto [31]. Briefly, 0.3 mL of sample solution (0.1 mg/mL) was mixed with 3.0 mL of reagent solution (0.6 M sulfuric acid, 28 mM sodium phosphate and 4 mM ammonium molybdate). Reaction mixture was incubated at 95 曟 for 90 min under water bath. Absorbance of all the sample mixtures was measured at 695 nm. Total antioxidant activity is expressed as the number of equivalents of ascorbic acid. A calibration curve of ascorbic acid was prepared and the total antioxidant activity was standardized against ascorbic acid equivalents per gram of sample on a dry weight basis.