FRAP value
was calculated using the linear slope of standard curves of compounds
obtained at 4 min versus the linear slope of ferrous sulfate standard
curve (conducted in the same manner as other samples) obtained at 4
min. In order to compare the FRAP assay with the DPPH assay, the
FRAP value was also expressed in TROLOX equivalents using the
linear slope of the compounds tested versus that of TROLOX (12).