2.4. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity
The extract was tested for its ability to scavenge DPPH
radicals by DPPH radical
scavenging assay as described previously (Blois, 1958). Three milliliters of 0.1 mM
DPPH
in ethanol was added to 0.5 ml of MPEE extract or green tea extract and incubated for 30 min in the dark at RT. Absorbance was read at 517 nm using a UV–vis
Spectrophotometer. The percentage of free radical scavenging activity was
calculated using the formula
%DPPH inhibition
¼ð1Absorbance in the presence of extract=Absorbance in the absence of extractÞ
100
The antioxidant activity of the extract was expressed as IC50(the concentration
of the extract required to inhibit DPPH radicals by 50%), as calculated using GraphPad Prism 5 software (San Diego, CA, USA).