The antioxidant capacity of the different extracts was evaluated
through their free radical-scavenging activity on the 1,1-diphenyl-2-
picrylhydrazyl (DPPH) radical based on the method of El-Massry,
El-Ghorab, and Farouk (2002). Different aliquots of extract solutions
prepared by adding 20 mg of methanolic extract and 10 mL of
methanol were mixed with 2 mL of DPPH methanolic solution
(4.7%). The mixture was thoroughly vortex-mixed and left to stand
at room temperature for 30 min. Next, absorbance was measured at
517 nm against a methanol blank without DPPH and in this test, the
percentage of DPPH inhibition was compared to that of gallic acid
(negative control). The results are expressed as percent inhibition of the DPPH radical (% inhibition DPPH), which was calculated according
to the following Eq. (2):