1- diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay
The experimental procedure was adapted from the method of Liu et
al.(63) and Basuny et al.(64). The reaction mixture contained freshly prepared 248
μM ethanol solutions of DPPH• (50 μL) and various concentrations of butanol
solution of the test substances, were added with a final volume of 200 μL in sterile
disposable 96-well microplate for all of the assays. (±)-α-Tocopherol served as known
antioxidants. Results were determined after 30 min of reaction time in order to analyze
antiradical activities. The disappearance of the free radical DPPH• was measured
spectrophotometrically at 540 nm with a microplate reader (64). The percentage inhibition
was calculated by the following equation (1)