The ABTS decolorization assay was performed as described [16], with slight modification. The ABTS cation radical (ABTS∙+) was produced by reacting 7 mM stock solution of ABTS with 2.45 mM potassium persulfate (final concentration) and allowing the mixture to stand in the dark for 6–8 h at room temperature before use. The ABTS∙+solution was diluted to an absorbance of 0.7 ± 0.02 at 734 nm. Thirty microliters of samples of different concentrations were mixed with 170 μl of ABTS∙+ working solution under a dark condition and shaken for 15 s. The absorbance was measured at 734 nm after 20 min. The scavenging capacity was calculated using the same formula as for the DPPH radical scavenging assay.