2.6. ABTS•+ radical cation scavenging activity assay
Antioxidant activities of the samples before and after the gastric
and duodenal phases of digestion were analyzed by investigating
their ability to scavenge the ABTS•+ radicals using the
method as described previously (Ozgen et al., 2006). The ABTS•+
(7 mM in 20 mM sodium acetate buffer, pH 4.5) was mixed with
2.45 mM potassium persulfate, and this mixture was allowed
to stand for 12–16 h at room temperature in the dark to create
a stable, dark blue–green radical solution.The solution was then
diluted with 20 mmol sodium acetate buffer (pH 4.5) to an absorbance
of 0.700 ± 0.001 at 734 nm to form the test reagent.
All samples were diluted approximately to provide 20%–80%
inhibition of the blank absorbance. One hundred microliters
of the test sample were thoroughly mixed with 3 mL of the prepared
reagent.The mixture was incubated at room temperature
for 1 h, and the absorbance at 734 nm was immediately recorded
with a Rui Li U9600 UV–vis spectrophotometer. Trolox
was used as a reference standard, and the results were expressed
as mol Trolox/g dry weight of flower.