vette, and 2 mL of 2×10−4
mol L−1
ethanol solution of
DPPH was added. Absorbance measurements commenced
at 517 nm with spectrophotometer immediately. The decrease in absorbance was determined continuously at every
5 min intervals until the reaction reached a steady state. The
EC50 value defined as the amount of antioxidant necessary
to decrease the initial DPPH concentration by 50% was determined. All the tests were performed in triplicate and the
results were averaged.