5. DPPH free radical scavenging activity
The method of Brand-Williams et al. (1995),based on the reduction of DPPH radical solution in the presence of hydrogen donating antioxidants,was used with some modifications. 0.8 mM DPPH radical solution in 95% ethanol was prepared. Four
hundred μl of the extract was diluted to 5.4 ml using deionized water and 95% ethanol (1:1) before 0.6 ml DPPH solution was added, and shakenvigorously. The decrease of absorbance was recorded at 1, 5, 10, and 30 min after mixing.Trolox (0-50 μg) and vitamin C (0-40 μg) wereused as standards, and results were reported as mg Trolox and vitaminC equivalent per gram of dry weight. The concentration of a selected extract was varied to find out the effective concentration at 50% inhibition (EC50).