ascorbic acid

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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]
(biochemistry)
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 ?
Based on the obtained results, in patients with untreated JIA, we found a significant reduction of serum concentrations of CS, quantified by the hexuronic acid assay.
Increased hexosamine, hydroxyproline, and hexuronic acid content reflects the stabilization of collagen molecules by enhancing electrostatic and ionic interactions.
The total glycosaminoglycans samples from the chicken comb and the fractions obtained through the ionic exchange chromatography were applied (~5 [micro]g in hexuronic acid) to a 0.5% agarose gel prepared in a 50mM diaminopropane (pH 9.0) buffer and submitted to 110V for almost 1h (DIETRICH & DIETRICH, 1976).
In hexuronic acid, Szent-Gyorgyi had discovered vitamin C, but he did not yet know what he had.
Since its molecules seemed to have six carbon atoms and since it had the properties of a sugar, Szent-Gyorgyi named it hexuronic acid.
Hyaluronic acid is composed of hexuronic and amino sugar with acetyl groups ((1[right arrow]3)-[beta]-D-GlcNAc-(1[right arrow]4)-[beta]-D-GlcA) for which the liver is the major tissue for the removal and synthesis of that.
It wouldn't be until 1928 that Hungarian biochemist Albert Szent-Gyorgyi first isolated vitamin C from plant juices and adrenal gland extracts, naming it hexuronic acid, now known as ascorbic acid.