The hydrogen donating ability of each extract in the presence of DPPH (2, 2-diphenyl-1-
picrylhydrazyl) stable radical was examined according to method developed by Blois17 and Cao et al.18 All
extracts were diluted with vehicle control to final extract concentration (0.1 to 0.9 mg/mL). 0.1 mL of test
sample at different concentration (0.1-0.9 mg/mL) was mixed with 0.9 mL of Tris-HCl buffer (pH 7.4); then
1 mL of DPPH (500 μM in ethanol) was added. The mixture was shaken vigorously and left to stand for 30
min. The absorbance of ethanolic DPPH tincture from DPPH* (violet color) to DPPH (clear) was measured
at 517 nm19 in a spectrophotometer and compared with synthetic anti-oxidant butylated hydroxyl anisole
(BHA). The experiment was repeated thrice. The percentage of DPPH scavenging was calculated using the
following formula: