Use of K Value of Ascorbic Acid as a Clinical Index of Attack by Oxygen Radicals

Abstract

The K value = [AFR]2/[RAsA] [DAsA ] (RAsA, reduced form of ascorbic acid; DAsA, oxidized form of ascorbic acid; AFR, ascorbate free radical), and changes in AFR concentration in human serum were examined after exposure to oxygen radicals. After the exposure, RAsA decreased, DAsA increased, and K value increased. Since the K value is constant in healthy subjects, it is regarded to be a clinical index to indicate the attack of oxygen radicals in living system. Whereas changes in AFR concentration in ascorbate solutions showed a one-way decrease after an initial increase, changes in serum were those of a persistent pattern with slight fluctuation after the initial increase. The difference was found to be attributable to the presence of a serum factor that inhibits ascorbate oxidation.

Cytoprotective Effect of .ALPHA.-Tocopherol against Parietal Cell Vacuolar Degeneration Induced by Omeprazole in Guinea Pig Gastric Mucosa.

“…In a study using the electron spin resonance (ESR) method, we previously found that OPZ increases in the ESR signal intensity of ascorbate radical (AFR) in vitro and that OPZ acts like oxygen radicals in altering the K value of ascorbic acid, which can be used as an index of free radical exposure in vivo [3,4]. Vitamin E exerts an anti-oxidant action by preventing the lipid peroxidation of unsaturated fatty acids in phospholipids containing peroxy radicals in biological cell membranes [5], and it also has a direct effect on oxygen radicals such as ringlet oxygen (102), superoxide (02-), and hydroxy radical • OH [6,7].…”