The corresponding
mixtures were kept in the darkness at rt for 30 min and then,
the absorbance was measured at 515 nm against a blank (MeOH).
Plotting the values of DPPH remaining vs. extract concentration
allows a straight line from which the EC50 (the concentration of
the antioxidant required to reduce the concentration of the DPPH
to 50% of its initial value) is calculated.