Nature of serum ascorbate radical and its quantitative estimation.

Influences of sex and age on serum ascorbic acid.

“…Methods of chemical determination of the concentrations of total and oxidized form of ascorbic acid and methods to obtain the ESR intensity were described elsewhere (Sasaki et al 1982(Sasaki et al , 1983. The concentration of reduced form was calculated by subtracting the concentration of oxidized form from that of total ascorbic acid.…”

“…ascorbic acid; reduced form; oxidized form; ascorbate radical; sex difference; age There has been considerable evidence that ascorbic acid functions as a defense against active oxygen radicals in addition to superoxide dismutase (Nishikimi 1975;Fessenden and Verma 1978;Bodaness and Chan 1979). The authors previously examined the nature of serum ascorbate radical and reported that both the ESR intensity of ascorbate radical and the concentrations of total and oxidized form of ascorbic acid in human serum declined with age, and that the decline in the level of ascorbic acid as well as ascorbate radical would indicate the decline in the defense mechanism with advancing age (Sasaki et al 1982(Sasaki et al , 1983. From this standpoint, it is of great interest to examine whether or not there is a sex difference in the concentration of ascorbic acid in serum.…”

Significance of the equilibrium constant between serum ascorbate radical and ascorbic acids in man.

“…Blood was drawn early in the morning before breakfast. All ESR measurements were carried out with a Varian E-109E X-band EPR spectrometer at room temperature as previously reported (Sasaki et al 1982(Sasaki et al , 1983a.…”

“…The method to determine (RAsA) and (DAsA) was described elsewhere (Sasaki et al 1982(Sasaki et al ,1983b. In order to examine the effects of administration of ascorbic acid in healthy subjects, 47 volunteers were selected at random from 244 controls.…”

“…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).…”