Vitamin C is found in the form of ascorbic acid-dehidroaskor binovi acids (reversibly oxidized form) and askorbigen (related form).
Ascorbic acid is a lactone enoliziran b. Keto-2-alpha-gulinova acid. The presence of dienolnata group determines its highly restorative properties. Ascorbic acid is reversibly oxidized to dehydroascorbic. Dehydroascorbic acid represents by itself diketolaldonova 2,3-lactone acid.
Recovery of ascorbic acid into dehydroascorbic it quickly in the presence of sulfhidridni compounds (such as cysteine, glutathione), tioglikoleva acid. Catalysts for this process also appears flavonoids.
In its irreversible oxidation ascorbic acid is converted into 2,3-diketogulinova and treonova acid.
In animal and plant tissues only part of ascorbic acid is in free state, its other part is permanently linked to proteins or nucleic acids and becomes available for oxidation only after its separation from the past. This form of ascorbic acid is called askorbigen.
Received in the human organism with food prosmukva ascorbic acid is mainly in the small intestine. Its maximum amount is in the blood after its adoption, after 4 hours. In the body of a healthy person, total ascorbic acid is from 3 to 6 in blood plasma containing an average of 0,7-1,2 mg per 100 ml, WBC - 20-30 mg.
All plants and many animals synthesize ascorbic acid, with the exception of guinea pigs, monkeys and humans. In their absence two ferments: D-glyukoronreduktaza alpha-and gamma-gulono laktonoksidaza that deliver the synthesis of ascorbic acid from glucose.
No doubt that the primary biochemical functions of ascorbic acid are closely related to its fundamental chemical properties - the ability to fast and reversible oxidative recovery processes. This enables it to serve as a hydrogen donor in numerous recreational events, as well as intermediate conveyor of protons and electrons in different oxidative-restorative processes. Ability to format a svobodnoradikalna semihinonova form of ascorbic acid provides an opportunity for active participation in the reactions of oxidation and hydroxylation svobodnoradikalnoto.
Most reliably established biochemical function of ascorbic acid appears to participate in the hydroxylation of proline in oksiprolin prokolagena the conversion of a major connective tissue protein collagen. Ascorbic acid may participate in other hydroxylation reactions: microsomal hydroxylation of xenobiotics, hydroxylation of cholesterol, steroid hormones, the conversion of tryptophan to 5-oksitriptofan and others. Ascorbic acid is also necessary for normal metabolism of tyrosine-deficit intensifies its transformation in the last homogentizinova, n-and n-oksifenilpropionova oksifenilmlechna acid.
Ascorbic acid is related to carbon exchange. Its deficiency disturb the normal absorption of glucose. Vitamin C also prevents the development of sclerosis, promote oxidation and removal of cholesterol from the body. High levels of ascorbic acid in certain organs with internal secretion (adrenal glands, pituitary, gonads) testifies to the important role in the metabolism of hormones.
The metabolism of ascorbic acid is associated with metabolism of other vitamins. Is proven synergism of action of vitamins C and B1. Ascorbic acid has a protective effect also of pantothenic and nicotinic acids, contribute to fermentnoto convert folic acid into its active forms kofermentni. Simultaneous introduction of ascorbic acid and folic acid in the body of the sick Avitaminosis-C, as well as folic failure, contributing to the rapid treatment of anemia alimentarna. Ascorbic acid plays an important role in the metabolism of vitamin E in the body, facilitating the recovery of tocopherol molecules, susceptible to oxidation by reactions with active forms of oxygen svobodnoradikalni. Ascorbic acid also has a protective effect on the number of mineral substances, facilitating, for example, the absorption of calcium and iron.
Described is the variety of other effects of vitamin C. It is evident that ascorbic acid plays a fundamental biochemical and physiological role in facilitating the normal development of connective tissue, the processes of regeneration and strengthening, increase the body's resistance to various types of stress, maintaining processes of normal blood formation and immune status of the organism.
Results of numerous scientific studies have shown that vitamin C-deficiency is a decrease in imunobiologicheski effects such as Complementary fagotsitarna activity and blood titres of specific antibodies.
The boom of colds somewhat coincides with the failure of seasonal foods rich in vitamins A and C and riboflavin, and also by lowering the content of these vitamins in products with long storage period. It was found that additional intake of vitamins, first, ascorbic acid, increases the body's resistance to infectious diseases.
Hipovitaminozata of vitamin C in humans develops in part the inclusion of vitamin C in ratsiona of nutrition in increased demand on the body thereof, in violation of the processes of its suction or absorption. This process can last for years without clear clinical symptoms appear. It is difficult to ascertain at what stage of using the reserves of ascorbic acid in the body comes first clinical disorders. The earliest clinical symptoms of deficiency of vitamin C appears to be pinpoint bleeding of the skin (petechiae), determined by lowering the resistance of capillaries. Subsequently hipovitaminozata of vitamin C is characterized by nonspecific symptoms, predominantly from nervous system and weakness. In developing Avitaminosis - C is seen perifolikulyarni hyperkeratosis, pain in legs, Scrappy color of skin, bleeding in the hair follicles and lower edges in the knees, bruising in the areas of knee joints, the back of the thighs, in places of former trauma and compression of shoes and clothes.
Vatremishnichni arise and subcutaneous bleeding in the shoulders. All of these phenomena in 75% of cases are accompanied by subfebrilna temperature. Along with bleeding in Avitaminosis-C or develop hipohlorhidriya ahlorhidriya, constipation first, then disorder hipohromna anemia. Following the lowering of the immunity of the body is marked increased susceptibility to infections. Healing of wounds and bone fractures runs slow and difficult.
Laboratory detection and hipovitaminozata Avitaminosis, lies in the determination of ascorbic acid in blood and urine. Its content in plasma decreased very quickly after being expelled from vitamin nutrition. Ascorbic acid disappears from the urine more rapidly than from plasma. The determination of its content is determined by time diagnostic significance. The content of ascorbic acid in leukocytes reaching zero values for only 4 months after its exclusion from the diet, when they appear the first clinical signs of hipovitaminoza - Si Avitaminosis.
Nonstop need for ascorbic acid for adults is 70-80 mg in domestic and favorable climatic conditions. The factors that increase the need for this vitamin include: smoking, heavy physical work, neuro-emotional stress, pregnancy, nursing, rehabilitation after serious illnesses, operations, need to strengthen the body's immune system. Under the rules in Russia, the daily consumption of vitamin C should be: for males - 70-100 mg; for women - 70-80 mg, for pregnant women, 90-100 mg; for nursing-110-120 mg, for adults, 80 mg, for children up to 1 g-30-40 mg; Zg. to-45 mg; to 6 years-80 mg; to 10 yrs-60 mg;-17-70 mg.
Of food sources of vitamin C are: hips, black grapes, red peppers, peas, lemon. Vitamin C is found in green onions, white cabbage, potatoes. Vitamin C has a high sensitivity to conditions of technological processing. Rubbing and squeezed and thermal treatment lead to a loss of ascorbic acid.
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