destroy potential oxidants, and to scavenge ROS. Thus, A simple, automated test measuring the ferric reducoxidative stress-induced tissue damage is minimized. ing ability of plasma, the FRAP assay, is presented as However, an absolute or relative deficiency of antioxia novel method for assessing ''antioxidant power.'' Ferdant defenses may lead to a situation of increased oxiric to ferrous ion reduction at low pH causes a colored dative stress, and this may be associated with both ferrous-tripyridyltriazine complex to form. FRAP valthe causes and consequences of a variety of disorders, ues are obtained by comparing the absorbance change including coronary heart disease and cancer (6-13).
at 593 nm in test reaction mixtures with those con-Tests which measure the combined antioxidant effect taining ferrous ions in known concentration. Abof the nonenzymatic defenses in biological fluids may sorbance changes are linear over a wide concentration be useful in providing an index of ability to resist oxidarange with antioxidant mixtures, including plasma, tive damage (13-19). Most tests of ''total antioxidant and with solutions containing one antioxidant in puripower'' used to date have measured the ability of fied form. There is no apparent interaction between plasma to withstand the oxidative effects of reactive antioxidants. Measured stoichiometric factors of Trospecies purposefully generated in the reaction mixture. lox, a-tocopherol, ascorbic acid, and uric acid are all Depletion of antioxidants is denoted by a change in 2.0; that of bilirubin is 4.0. Activity of albumin is very signal, such as rate of oxygen utilization (17) or chemilow. Within-and between-run CVs are õ1.0 and õ3.0%, luminescence (16-19). Measurement of these signals respectively, at 100-1000 mmol/liter. FRAP values of requires specialized equipment, and such tests can be fresh plasma of healthy Chinese adults: 612-1634 time-consuming as well as technically demanding. This mmol/liter (mean, 1017; SD, 206; n Å 141). The FRAP limits the availability of such tests and, furthermore, assay is inexpensive, reagents are simple to prepare, makes clinical evaluative studies difficult. results are highly reproducible, and the procedure is straightforward and speedy. The FRAP assay offers a 2 Abbreviations used: ROS, reactive oxygen species; FRAP, ferric reducing ability of plasma; Fe III -TPTZ, ferric-tripyridyltriazine.
power may be referred to analogously as reducing abil-70