Antioxidant activity of grape seed extracts was determined using the thiocyanate method (Yen & Hsieh,
1998). The linoleic acid emulsion was prepared by
homogenizing 0.28 g of linoleic acid, 0.28 g of Tween-40
as emulsifier and 50 ml of phosphate buffer (0.2 M, pH
7.0). Test samples were prepared in MeOH: water mix-
ture (6:4 v/v). Different test samples (0.5 ml) were mixed
with 2.5 ml of linoleic acid emulsion and 2.5 ml of
phosphate buffer (0.2 M, pH 7.0) and incubated at 37? C
for 120 h. The mixture prepared as above without test
sample served as control. Aliquots (0.1 ml) were drawn
from the incubation mixture at an interval of 20 h and
mixed with 5.0 ml of 75% ethanol, 0.1 ml of 30%
ammonium thiocyanate and 0.1 ml of 20 mM in ferrous
chloride in 3.5% HCl and allowed to stand at room
temperature for 3 min. The colour developed was measured at 500 nm. The degree of linoleic acid peroxidation was calculated at 100 h using the following formula
(Pin-Der Duh, 1998).
Antioxidant activity of grape seed extracts was determined using the thiocyanate method (Yen & Hsieh,1998). The linoleic acid emulsion was prepared byhomogenizing 0.28 g of linoleic acid, 0.28 g of Tween-40as emulsifier and 50 ml of phosphate buffer (0.2 M, pH7.0). Test samples were prepared in MeOH: water mix-ture (6:4 v/v). Different test samples (0.5 ml) were mixedwith 2.5 ml of linoleic acid emulsion and 2.5 ml ofphosphate buffer (0.2 M, pH 7.0) and incubated at 37? Cfor 120 h. The mixture prepared as above without testsample served as control. Aliquots (0.1 ml) were drawnfrom the incubation mixture at an interval of 20 h andmixed with 5.0 ml of 75% ethanol, 0.1 ml of 30%ammonium thiocyanate and 0.1 ml of 20 mM in ferrouschloride in 3.5% HCl and allowed to stand at roomtemperature for 3 min. The colour developed was measured at 500 nm. The degree of linoleic acid peroxidation was calculated at 100 h using the following formula(Pin-Der Duh, 1998).
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