2,2-Diphenyl-1-picrylhydrazyl (DPPH)
Antioxidant capacity of polyphenols extract was carried out
using DPPH assay as described by with Wu, Zhang, and Wang
(2012) some modifications. 0.025 g L1 of methanolic DPPH was
freshly prepared before analysis was carried out. A 20 ll of aliquot
of the extract was mixed with 200 ll of DPPH in a 96-well microplate
and incubated in the dark at room temperature for 30 min.
Blank was prepared by replacing 20 ll of extract with 20 ll of
methanol. The absorbance of value was measured against blank
at 517 nm using microplate spectrophotometer. A standard curve
(R2 = 0.9924) was established by using 20 ll of different concentrations
of trolox (100–500 lM). The decrease in absorbance of samples
in DPPH solution due to the scavenging of DPPH free radicals
was determined from the standard curve and results were
expressed as mM of trolox equivalent (TE) g1 FW.