The main and modified CUPRAC methods of antioxidant measurement

The antioxidant activity/capacity levels of biological fluids and foods are measured for the diagnosis and the treatment of oxidative stress-associated diseases in clinical biochemistry, and for meaningful comparison of the antioxidant content of foods. Currently, there is no “total antioxidant” as a nutritional index available for food labeling and biological fluids due to the lack of standardized quantitative methods.The CUPRAC (CUPric Reducing Antioxidant Capacity) method of antioxidant measurement, introduced by our research group, is based on the absorbance measurement of Cu(I)-neocuproine (Nc) chelate formed as a result of the redox reaction of chain-breaking antioxidants with the CUPRAC reagent, Cu(II)-Nc, where absorbance is recorded at the maximal light-absorption wavelength of 450 nm.We introduce the main CUPRAC method and describe modifications to it in the past six years.