The ABTS radical scavenging activity was carried out by the
method described by Re et al. (1999) with some modifications. ABTS
radical solution was produced by mixing ABTS aqueous solution
(final concentration 7 mmol/L) with potassium persulphate (final
concentration 2.45 mmol/L), and the mixture was incubated in the
dark at room temperature for 16 h. After incubation, the ABTS radical
solution was diluted with PBS (pH 7.0) to an absorbance of
0.70 (±0.02) at 734 nm. The polysaccharide samples were dissolved
in distilled water to form sample solution in final concentrations
of 0.1, 1, 2, 3, 4, and 5 mg/mL, respectively. The sample solution
was added to ABTS radical solution in a ratio of 1:20, and the mixture
solution was incubated for 6 min at room temperature. The
absorbance was measured at 734 nm. The scavenging activity on
ABTS radical was calculated by the following formula.
Scavenging activity(%)
=
1
−
Asample
Acontrol
×
100
where Acontrol is the absorbance of the ABTS radical solution without
sample and Asample is the absorbance of the ABTS radical solution
with tested samples.