ABTS radical scavenging activity. ABTS radical scavenging
activity was determined as described by Binsan et al.
(2008). The stock solutions included 7.4 mM ABTS solution
and 2.6 mM potassium persulphate solution. The working
solution was prepared by mixing two stock solutions in equal
quantities and allowing them to react for 12 h at room temperature
in dark. The solution was then diluted by mixing
1 mL of ABTS solution with 50 mL of methanol in order to obtain
A734 of 1.1 ± 0.02 using a spectrophotometer. Fresh ABTS
solution was prepared daily. Sample (1 mg/mL; 150 lL) was
mixed with 2850 lL of ABTS solution and the mixture was left
at room temperature for 2 h in dark. The absorbance was then
measured at 734 nm using a spectrophotometer. A standard
curve of Trolox ranging from 50 to 600 lM was prepared.
The activity was expressed as lmol Trolox equivalents (TE)/g
sample.