Significance of Measurement: Total antioxidant capacity (T-AOC) reflects the combined action of enzymatic and non-enzymatic antioxidants in biological samples. It provides an overall assessment of the antioxidant defense system. Principle of Measurement: Antioxidants in the sample reduce Fe3+ to Fe2+, which forms a stable colored complex with chromogenic reagents. The absorbance measured at 593 nm is proportional to total antioxidant capacity.