2.4. In vitro antioxidant assay
2.4.1. ABTS radical scavenging assay
The radicals scavenging activity of the essential oil against
radical cation (ABTSþ) was estimated according to the previously
reported procedure with some modifications (Re et al., 1999).
ABTSþ was produced by reacting 7 mmol/L of ABTSþ solution with
2.45 mmol/L of potassium persulphate, and the mixture would be
kept in the dark at room temperature for 16 h. In the moment of
use, the ABTSþ solution was diluted with ethanol to an absorbance
of 0.70 0.02 at 734 nm. Each sample (0.2 mL) with various
concentrations (0.2e1.0 mg/mL) were added to 2 mL of ABTSþ
solution and mixed vigorously. After reaction at room temperature
for 6 min, the absorbance at 734 nm was measured. The ABTSþ
scavenging effect was calculated by the following formula: