The positive and negative
controls were subjected to the same procedures as the test samples
except that, for the negative control, only the DW was added and
a-tocopherol (0.5 and 1 mg/ml) was used as a positive control.
The absorbance was measured at 500 nm wavelength, every day,
until the absorbance of the control reached its maximum value.
We continued the experiment for up to 6 days. The scavenging
activity was calculated by using the following equation: