1.5.3. Total antioxidant capacity (TAOC)
The basis for this assay was the reduction of Molybdenum VI to
Molybdenum (V) and formation of a green phosphate/Molybdenum (V) complex
in acidic conditions (Prieto et al ., 1999). Different
concentrations (25, 50, 100, 200 and 400 μg/ml) were prepared by
dissolving the extracts/fractions in distilled water. 0.3 ml of the
extract/fraction mixed with 3 ml of reagent. Reagent solution comprises
of mixture of various reagent like sulfuric acid (0.6 M), sodium
phosphate (28 mM) and ammonium molybdate (4 mM). After mixing both
sample and reagent solution, mixture was incubated for 90 min (95˚C)
after covering the test tubes with aluminium foil. Absorbance was
recorded at 695 nm after cooling the solution at room temperature,
against blank. Similar procedure was carried out with ascorbic acid
which is used as standard. The total antioxidant activity was expressed
as absorbance of the sample. A higher absorbance value would indicate a
higher antioxidant activity (Li and Wang, 2011).