This study was performed to determine whether synthetic ascorbic acid (AA) alone or in a natural citrus extract containing bioflavonoids, proteins, and carbohydrates was more bioavailable to human subjects. The effect of a single 500-mg ascorbate dose of the two forms and a placebo citrus extract on plasma ascorbate was examined in eight fasting subjects. A comparison of the areas under the pla...

Effect of Ascotbate on Covalent Binding of Benzene and Phenol Metabohtes to Isolated Tissue Preparations. SMART, R. C. and ZANNONI, V. G. (1985). Toxicol. Appl. Pharmacol. 77, 334-343. [‘4C]Phenol and [‘4C]benzene are metabolized in the presence of NADPH and hepatic microsomes isolated from phenobarbitalor benzene-pretreated or untreated guinea pigs to intermediates capable of covalently bindin...

Ascorbic acid is one of the most well-known nutritional supplement and antioxidant found in fruits and vegetables. Calcium ascorbate has been developed to mitigate the gastric irritation caused by the acidity of ascorbic acid. The aim of this study was to compare calcium ascorbate and ascorbic acid, focusing on their antioxidant activity and effects on gastric juice pH, total acid output, and p...

The Arabidopsis thaliana ascorbate-deficient vtc-1 mutant has only 30% ascorbate contents of the wild type (WT). This ascorbate-deficient mutant was used here to study the physiological roles of ascorbate under salt stress in vivo. Salt stress resulted in a more significant decrease in CO2 assimilatory capacity in the vtc-1 mutant than in the WT. Photosystem II function in the Arabidopsis vtc-1...

Ruptured pea (Pisum sativum cv. Massey Gem) chloroplasts exhibited ascorbate peroxidase activity as determined by H(2)O(2)-dependent oxidation of ascorbate and ascorbate-dependent reduction of H(2)O(2). The ratio of ascorbate peroxidase to NADP-glyceraldehyde 3-phosphate dehydrogenase activity was constant during repeated washing of isolated chloroplasts. This indicates that the ascorbate perox...

Plasma ascorbic acid concentrations were determined in eight men and nine women over age 65 on controlled intakes of vitamin C. Plasma ascorbic acid levels were significantly lower in elderly men compared with women for vitamin C intakes ranging from 30 to 280 mg/d. A maximum steady-state level of 1.0 mg/dL (56.78 mumol/L) ascorbic acid was observed in male subjects at an intake of approximatel...

Ascorbic acid is an essential nutrient commonly regarded as an antioxidant. In this study, we showed that ascorbate at pharmacologic concentrations was a prooxidant, generating hydrogen-peroxide-dependent cytotoxicity toward a variety of cancer cells in vitro without adversely affecting normal cells. To test this action in vivo, normal oral tight control was bypassed by parenteral ascorbate adm...

Ascorbic acid is a well-known antioxidant and radical scavenger. It can be oxidized by losing two protons and two electrons, but normally loses only one electron at a time. The reactivity of the ascorbate radical is unusual, in that it can either disproportionate or react with other radicals, but it reacts poorly with non-radical species. To explore the oxidation mechanism of ascorbic acid, the...

Falciparum malaria infection is associated with significant destruction of erythrocytes. This leads to the release of toxic metabolic products, including oxidant compounds. We measured the serum concentration of the antioxidant, ascorbic acid, in 129 patients presenting with acute falciparum malaria infection and in 65 healthy individuals. None of the study subjects administered any form of asc...

Ascorbic acid (vitamin C) has followed opaque paths in treating pharmacologic ascorbate. Because myeloma cells are iron-rich, increasmultiplemyeloma, and othermalignancies. Inmyeloma cells, ascorbate surprisingly depleted glutathione and potentiated arsenate trioxide efficacy. Because oral ascorbate at 1 g produces plasma saturation, this dose was selected with arsenate. Predictably, in small t...