A Novel Assay for Measuring Total Antioxidant Capacity in Whole Blood and Other Biological Samples

A new method for rapidly determining total antioxidant capacity (TAC) in a biological sample has been devised and evaluated. A surfactant present in the reagent causes the lysis of cells in the sample. Glutathione, ascorbic acid, protein thiols and other main antioxidant substances in the sample react with a specific redox chromogen (2,6-dichlorophenolindophenol) and produce a change in the color of the reagent, which is determined photometrically at 630 nm. This new method quantifies the overall capacity of the sample to reduce a redox chromogen and it requires the minimum volumes and time. The assay can be used on a wide variety of biological samples including whole blood, serum, plasma, tissue extracts and homogenates, food, wine, fruit juice and other beverages. Results are expressed in terms of mmol/L glutathione equivalents. TAC can be assayed manually, on automatic analyzers or micro-plate readers.