2.6. ABTS radical-scavenging activity
ABTS was dissolved in DW at a final concentration of 7 mM and
mixed with a potassium persulphate solution at a final concentration
of 2.45 mM. The reaction mixture was left to settle at RT for
12–16 h in the dark before use (Jeong et al., 2009). For each experiment,
freshly prepared ABTS+ solution was diluted with 0.01 M
phosphate buffer saline (PBS, pH 7.4) to adjust its absorbance to
within 0.70 ± 0.02 at 734 nm wavelength. Then 0.1 ml of various
concentrations of the sample (0.12–2.00 mg/ml) and BHT (0.025–
0.125 mg/ml) was mixed with 0.9 ml of ABTS+ solution. Finally,
the absorbances were measured at 734 nm after incubation at RT
for 5 min. The scavenging activity of ABTS free radical was calculated
by using the following equation:
ABTS scavenging activityð%Þ ¼ fðC DÞ ðA BÞ=ðC DÞg 100;
where, A = absorbance of ABTS solution + sample/standard, B =
absorbance of potassium persulphate + sample/standard, C = absorbance
of ABTS solution + DW/methanol and D = potassium persulphate
+ DW/methanol.