Vitamin C: Basic Metabolism and Its Function as an Index of Oxidative Stress

Abstract

Vitamin C (ASC) is well known as an outstanding antioxidant in animal tissues. This concept is reviewed from a chemical standpoint, starting from a chemical view of radical reactions in the cell. ASC, vitamin E, and lipid hydroperoxide were selected as key molecules involved in radical reactions in the cell, and their efficiencies as an index of oxidative stress were evaluated. At first, methods for specific and sensitive determination of ASC and lipid hydroperoxide were developed. Based on comparisons of these indices during oxidative stress in typical pathological conditions, such as diabetes and liver damage by toxicants, ASC concentration was found to be the most sensitive index in animal tissues. Antioxidative effect of food factors in vivo can be evaluated on the basis of these indices. Analysis of oxidation of low-density lipoprotein (LDL) revealed that degradation and cross-link of apolipoprotein B-100 (apoB) are extremely facile processes. Fragmented and conjugated apoB proteins are present in normal human serum, and tend to increase with age based on immunoblot analysis. Estimation of these products allows us a mechanism-based diagnosis of atherosclerosis. A significant relationship between plasma ASC level and the sum of these apoB products was found. In conclusion, specifically determined ASC concentration sensitively reflects oxidative stress in tissues.

Hyperpolarized 13 C dehydroascorbate as an endogenous redox sensor for in vivo metabolic imaging

“…Vitamin C is also an effective reducing agent protecting cells from the injurious effects of reactive oxygen species (4). Pauling championed the antiviral properties of Vitamin C, and cells of the immune system including mononuclear leukocytes and neutrophils are known to accumulate large quantities of ascorbate, which may be protective against free radicals generated during the respiratory burst (5)(6)(7).…”

“…Here we report the development of [1- 13 C] dehydroascorbate [DHA], the oxidized form of Vitamin C, as an endogenous redox sensor for in vivo imaging using hyperpolarized 13 C spectroscopy. In murine models, hyperpolarized [1-13 C] DHA was rapidly converted to [1][2][3][4][5][6][7][8][9][10][11][12][13] C] vitamin C within the liver, kidneys, and brain, as well as within tumor in a transgenic prostate cancer mouse. This result is consistent with what has been previously described for the DHA/Vitamin C redox pair, and points to a role for hyperpolarized [1][2][3][4][5][6][7][8][9][10][11][12][13] C] DHA in characterizing the concentrations of key intracellular reducing agents, including GSH.…”

Platelet-activating Factor Receptor Agonists Mediate Xeroderma Pigmentosum A Photosensitivity

“…4A). Antioxidants vitamin C and N-acetylcysteine can effectively scavenge a wide array of ROS and free radicals (52)(53)(54). The next set of experiments assessed their abilities to ameliorate UVB irradiationmediated ROS and PAF-R agonistic activity.…”

Synergistic protective role of ceftriaxone and ascorbic acid against subacute diazinon-induced nephrotoxicity in rats

“…It is highly water soluble and acts as an efficient reducing agent. AA is the most effective antioxidant in preventing lipid peroxidation initiated by peroxyl radicals, and considered as a potent free radical scavenger (El-Demerdash et al 2005;Kojo 2004). Moreover, it may restore other antioxidants such as vitamin E (Carr and Frei 1999).…”