2.7. Inhibition of linoleic acid oxidation
The inhibition of lipid peroxidation was determined by the
method of Lee et al. (2009) with a little modification; 2.5 ml of each
test sample (1 mg/ml) was mixed with 1 ml of 0.1 M sodium phosphate
buffer (pH 7.0), followed by addition of 1 ml of 50 mM linoleic
acid solution dissolved in 99% ethanol. After addition of 0.5 ml
of DW, the mixture was incubated at 40 C in a water bath in the
dark. Then 50 ll of the above mixture was mixed with 2.5 ml of
75% ethanol and 50 ll of 30% ammonium thiocyanate. After
3 min, 50 ll of 20 mM ferrous chloride was added to the mixture,
followed by incubation for 3 min at RT. The positive and negative
controls were subjected to the same procedures as the test samples
except that, for the negative control, only the DW was added and
a-tocopherol (0.5 and 1 mg/ml) was used as a positive control.
The absorbance was measured at 500 nm wavelength, every day,
until the absorbance of the control reached its maximum value.
We continued the experiment for up to 6 days. The scavenging
activity was calculated by using the following equation:
Scavenging activityð%Þ ¼ 100 ½ðB=AÞ 100;