ascorbic acid

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Related to ascorbic acid: citric acid

ascorbic acid:

see vitaminvitamin,
group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
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Ascorbic acid

A white, crystalline compound, also known as vitamin C. It is highly soluble in water, which is a stronger reducing agent than the hexose sugars, which it resembles chemically. Vitamin C deficiency in humans has been known for centuries as scurvy. The compound has the structural formula shown below.

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The stability of ascorbic acid decreases with increases in temperature and pH. This destruction by oxidation is a serious problem in that a considerable quantity of the vitamin C content of foods is lost during processing, storage, and preparation.

While vitamin C is widespread in plant materials, it is found sparingly in animal tissues. Of all the animals studied, only a few, including humans, require a dietary source of vitamin C. The other species are capable of synthesizing the vitamin in such tissues as liver and kidneys. Some drugs, particularly the terpene-like cyclic ketones, stimulate the production of ascorbic acid by rat tissues.

Vitamin C–deficient animals suffer from defects in their mesenchymal tissues. Their ability to manufacture collagen, dentine, and osteoid, the intercellular cement substances, is impaired. This may be related to a role of ascorbic acid in the forma- tion of hydroxy-proline, an amino acid found in structural proteins, particularly collagen. People with scurvy lose weight and are easily fatigued. Their bones are fragile, and their joints sore and swollen. Their gums are swollen and bloody, and in advanced stages their teeth fall out. They also develop internal and subcutaneous hemorrhages.

There is evidence that vitamin C may play roles in stress reactions, in infectious disease, or in wound healing. Therefore, many nutritionists believe that the human intake of ascorbic acid should be many times more than that intake level which produces deficiency symptoms. The recommended dietary allowances of the Food and Nutrition Board of the National Research Council are 30 mg per day for 1- to 3-month infants, 80 mg per day for growing boys and girls, and 100 mg per day for pregnant and lactating women. These values represent an intake which tends to maintain tissue and plasma concentrations in a range similar to that of other well-nourished species of animals. See Vitamin

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

ascorbic acid

[ə′skȯr·bik ′as·əd]
C6H8O6 A white, crystalline, water-soluble vitamin found in many plant materials, especially citrus fruit. Also known as vitamin C.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

ascorbic acid

a white crystalline vitamin present in plants, esp citrus fruits, tomatoes, and green vegetables. A deficiency in the diet of man leads to scurvy. Formula: C6H8O6
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
The quantum yield for oxidation of ascorbic acid with methylene green was calculated as a function of concentration of ascorbic acid, concentration of methylene green, temperature, and percentage composition of alcohols such as aqueous methanol, aqueous ethanol and aqueous isopropanol at different temperatures ranging from 303 K to 318 K.
The ascorbic acid content was determined by the titration method of AOAC (22) modified by Benassi & Antunes, (25) and the results were expressed in mg of ascorbic acid per 100 grams of sample.
Effect of ascorbic acid and acetylsalicylic acid supplementation of broiler diets on performance during the hot season.
A declining trend in ascorbic acid was observed at all temperatures with the passage of time.
2.3 Evaluation of ascorbic acid as antioxidant for Biodiesel
O'fallon et al., "Failure of High-Dose Vitamin C (Ascorbic Acid) Therapy to Benefit Patients with Advanced Cancer: A Controlled Trial," The New England Journal of Medicine, vol.
Experiment 3 compared a single dose of ascorbic acid by mouth (10 grams) that was equivalent with the amount given IV.
Effect of treatment with ascorbic acid at various concentrations on the in vitro development of SCNT embryos
Second-order models for prediction of protein, antioxidant, and ascorbic acid were developed in RSM.
Figure 5 showed the changes in the conversion with time for the direct esterification and transesterification in tert-butanol at 50[degrees]C with molar ratio of acyl donor to ascorbic acid of 5 : 1.
Objective: To assess anaemia and oxidative stress in rats that were injected lead and to evaluate the possible effects of ascorbic acid supplementation on these parameters.
"As ascorbic acid has a major influence on (re)generation of immune cells in vitro, we executed an observational study in which ascorbic acid serum values of patients with hematological malignancies treated with and without hematopoietic stem cell transplantation were compared with those of healthy volunteers to see if low ascorbic acid levels should be considered of importance regarding immune recovery of these patients," explained authors Mirelle Huijskens and colleagues.