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solution at different concentrations. The absorbance was measured at 517 nm using a
spectrophotometer after 30 min. A solution of DPPH was used as a negative control.
The DPPH radical scavenging activity was calculated with the following equation:
DPPH Scavenging activity (%) = Ac − As/Ac × 100 (where Ac is the absorbance
of negative control and As is the absorbance of sample, respectively).
2.7 Fe 2+ Chelating Activity
Metal Chelating activity was measured by the method of Hsu et al. (2003). Different
concentrations of flaxseed extracts were mixed with 0.1 ml of 2 mM FeCl 2 -4H 2 O,
0.2 ml of 5 mM ferrozine solution and 3.7 solvent were mixed in a test tube. After
10 min the absorbance was measured at 562 nm. Mixture without extract was used
as the control. The percentage of metal chelating activity was calculated using the
following equation: Iron chelating activity (Inhibition %) = [(Ac − As/Ac) × 100]
(where Ac = the absorbance of the control reaction and As = the absorbance in the
presence of the flaxseed extract.)
2.8 ABTS Radical Scavenging Activity
ABTS radical scavenging activity was measured by the method described by Re
et al. (1999), with modification. ABTS solution was prepared by mixing 5.0 mL of
7 mM ABTS solution with 88 of 140 mM potassium persulfate, and keeping in the
dark at room temperature for 16 h. Different concentrations of samples were mixed
with ABTS radical working solution and incubated for 15 min at room temperature
in dark. Absorbance was measured at 734 nm. ABTS radical scavenging activity
was calculated according to the following equation: ABTS (%) = (1- Absorbance of
sample/Absorbance of control) × 100.
2.9 Ferric Reducing Antioxidant Power Activity (FRAP)
Ferric reducing antioxidant power (FRAP) activity was based on the method of
Benzie and Strain (1996). Different concentrations of samples were mixed with 3 ml
of FRAP reagent and the mixture was incubated at 37 °C for 4 min. The absorbance
was measured at 593 nm. Fresh working solutions of FeSO 4 were used for calibration.
The result was expressed as µmol FeSO 4 equivalents per ml of sample.
S. Ghosal et al.
solution at different concentrations. The absorbance was measured at 517 nm using a
spectrophotometer after 30 min. A solution of DPPH was used as a negative control.
The DPPH radical scavenging activity was calculated with the following equation:
DPPH Scavenging activity (%) = Ac − As/Ac × 100 (where Ac is the absorbance
of negative control and As is the absorbance of sample, respectively).
2.7 Fe 2+ Chelating Activity
Metal Chelating activity was measured by the method of Hsu et al. (2003). Different
concentrations of flaxseed extracts were mixed with 0.1 ml of 2 mM FeCl 2 -4H 2 O,
0.2 ml of 5 mM ferrozine solution and 3.7 solvent were mixed in a test tube. After
10 min the absorbance was measured at 562 nm. Mixture without extract was used
as the control. The percentage of metal chelating activity was calculated using the
following equation: Iron chelating activity (Inhibition %) = [(Ac − As/Ac) × 100]
(where Ac = the absorbance of the control reaction and As = the absorbance in the
presence of the flaxseed extract.)
2.8 ABTS Radical Scavenging Activity
ABTS radical scavenging activity was measured by the method described by Re
et al. (1999), with modification. ABTS solution was prepared by mixing 5.0 mL of
7 mM ABTS solution with 88 of 140 mM potassium persulfate, and keeping in the
dark at room temperature for 16 h. Different concentrations of samples were mixed
with ABTS radical working solution and incubated for 15 min at room temperature
in dark. Absorbance was measured at 734 nm. ABTS radical scavenging activity
was calculated according to the following equation: ABTS (%) = (1- Absorbance of
sample/Absorbance of control) × 100.
2.9 Ferric Reducing Antioxidant Power Activity (FRAP)
Ferric reducing antioxidant power (FRAP) activity was based on the method of
Benzie and Strain (1996). Different concentrations of samples were mixed with 3 ml
of FRAP reagent and the mixture was incubated at 37 °C for 4 min. The absorbance
was measured at 593 nm. Fresh working solutions of FeSO 4 were used for calibration.
The result was expressed as µmol FeSO 4 equivalents per ml of sample.