The use of cyclic voltammetry for the evaluation of antioxidant capacity

Low-molecular weight antioxidants (LMWAs) play a major role in protecting b iological systems against reactive oxygen-derived species and reflect the a ntioxidant capacity of the system. Cyclic voltammetry (CV), shown to be con venient methodology, has been validated for quantitation of the LMWA capaci ty of blood plasma, tissue homogenates, and plant extracts. Analysis of the CV tracing yields the values of (i) the biological oxidation potential, E and E-1/2, which relate to the nature of the specific molecule(s); (ii) the intensity (Ia) of the anodic current; and (iii) the area of the anodic wav e (S). Both Ia and S relate to the concentration of the molecule(s). LMWA c omponents of human plasma and animal tissues were identified and further va lidated by reconstruction of the CV tracing and by high-performance liquid chromatography-elecrochemical detection. To reflect the oxidative stress st atus, the use of an additional parameter, R, has been proposed. R represent s the level (%) of oxidized ascorbate (compared with total ascorbate) and i s measured by high-performance liquid chromatography-electrochemical detect ion. All these parameters were monitored in healthy human subjects as well as in chronic (diabetes mellitus) and acute care patients (subjected to tot al body irradiation before bone marrow transplantation). The electroanalyti cal methodologies presented here could be widely employed for rapid evaluat ion of the status of subjects (in health and disease) for monitoring of the ir response to treatment and/or nutritional supplementation as well as for screening of specific populations. (C) 2000 Elsevier Science Inc.