2.6. ABTS radical scavenging method
The radical scavenging activity of EOs alone or in the presence
of CD was determined by using ABTS radical cation (ABTS•+)
(Prior, Wu, & Schaich, 2005). The method is based on the ability
of an antioxidant to scavenge and reduce ABTS•+ into its colorless
form. The ABTS•+ was generated by mixing 7 mM of ABTS
salt with 2.45 mM of K2S2O8 in water at room temperature in the
dark for 16 h. The ABTS•+ solution was then diluted with water
to obtain an initial absorbance of 0.75 ± 0.2 at 730 nm using UVvisible
dual-beam spectrophotometer (Perkin Elmer Lambda 2S)
with a 1 cm thick quartz cuvette. Aliquots of EOs alone or in the
presence of 10 mM of CD were added to 2 mL of ABTS•+. Mixtures
were shaken for 1 h and allowed to stand at dark at 25 ± 0.1 ◦C. The
absorbance wasmeasuredat 730 nm.Blank samples containABTS•+
alone or in the presence of 10 mM of CD. The antioxidant activity
was expressed as Trolox equivalents TEAC (mol Trolox/g of EO) by
using a Trolox calibration curve prepared for a concentration range
of 2.5–25 M. All analyses were done in triplicate