1,1-diphenyl-2-picrylhydrazyl (DPPH) radical
scavenging assay
DPPH radical scavenging activity of the aqueous
solution (1%) was estimated according to the method
of Blois (1958). Aqueous solution (1%) of 20 ll was
added to 480 ll of water and 500 ll of methanolic
DPPH solution (0.2 mM). The mixture was vortexed
and left to stand at room temperature for 30 min. A tube
containing 500 ll of distilled water and 500 ll of methanolic
DPPH solution (0.2 mM) served as the control.
The absorbance of the solution was measured spectrophotometrically
at 517 nm (UV 1600 PC, Shimadzu,
Tokyo, Japan). The percentage of DPPH scavenging
was obtained from the equation
Radical scavenging activity ð%Þ
¼ ðAControl ASampleÞ=ðAControlÞ.