Determination of DPPH radical scavenging activity

Samples were tested for their scavenging activity using DPPH radical cation as described by Kim, Guo & Packer (2002). Briefly, 0.4 mM of DPPH solution and serial dilutions of each sample were prepared. A total of 400 µL of a sample at different dilutions were thoroughly mixed with 400 µL of the DPPH solution. All mixtures were incubated in dark at room temperature for 30 min and absorbance was read at 517 nm. DPPH scavenging activity was computed according to the equation: Inhibition %= 1 – (A_sample/A_control) * 100

where A_sample is the absorbance of a sample and A_control is the absorbance of blank. Percentage inhibition was plotted against concentration and results were expressed as µM trolox equivalent per 100 g FW (µM TE/100 g FW). Extracts of three biological replicates of each experimental group were analyzed.