“…It has been reported that the stable ascorbate radical (AFR) can be easily observed in human serum at room temperature, the relative electron spin resonance (ESR) intensity of AFR is proportional to the total concentration of ascorbic acid, and both the relative ESR intensity and the total concentration of ascorbic acid decline with age (Sasaki et al 1982(Sasaki et al , 1983a). The AFR exists as the intermediate during the redox processes of the reduced form (RAsA) or the oxidized form (DAsA) of ascorbic acid, and 2 molecules of AFR disproportionate to yield RAsA and DAsA via an initial dimerization (Bielski et al 1981).…”