Name

L (+) - ascorbic acid is the chemical name of Vitamin C, a water-soluble, easily oxidizable Vitamin. The systematic name in accordance with IUPAC rules is (R) - 5 [(S) - 1,2-Dihydroxyethyl] - 3,4-dihydroxy-5H-furan-2-on. Vitamin C is derived from a The pKs value is with 4,2, the solubility in water (20 "°C) with 333 g/l. The molecular mass amounts to 176.13 g/mol. The E-number of ascorbic acid, as one finds it in effort lists with food, is E 300.

The chemical sum formula reads C6H8O6. The melting point is with 190-192 "°C. A boiling point cannot be indicated, since the substance already decomposes starting from the melting point.

From the ascorbic acid 4 different stereoisomers forms, which exhibit optical activity, exist there to 4. and 5. C-atom assymmetric centers are in each case:

• L-ascorbic acid (also or 3-Keto-L-gulofuranolacton)
• D-ascorbic acid

The molecules L and D-ascorbic acid behave like picture and mirror image to each other, them are Enantiomere, likewise L and

L-ascorbic acid and as well as D-ascorbic acid and are Epimere, it differ in each case in the configuration only one C-atom.

Vitamin C is the generic name for all connections, which exhibit the same biological effect as the L-ascorbic acid. D-ascorbic acid and are biologically inactive, exhibit only a small biological effectiveness.

The Dehydro L ascorbic acid (DHA) belongs to the group of the Vitamin C connections, since it is reduced in the body to L-ascorbic acid.

Biosynthesis

The formation of the ascorbic acid in the organism begins with the oxidation from UDP D glucose to UDP D Oxidizing agent is the NAD+ in presence of the enzyme UDP glucose Dehydrogenase. After hydrolytic splitting off of the UDP forms the which is transferred by selective reduction (NADPH/H+, Reduktase) in The Lactonisierung with Lactonase to the L-Gulofuranolacton follows the selective oxidation with oxygen and Gulofuranolacton Oxidase to the ascorbic acid.

Meaning

Vitamin C is a radical inhibitor and has an anti-oxidative effect (reducing agent). It is an important Cofaktor with the Hydroxylierungsreaktion and controls thereby the body-own production of collages. Beyond that it plays an important role with the structure of amino acids. Because of its reducing characteristic it is used also isolated as development substance in photographic developers and finds as anti-oxide to also in the food production use.

Task/function

The name ascorbic acid is derived from the illness scurvy, which can be prevented and healed by ascorbic acid. With Niacin and Vitamin B6 Vitamin C steers the production of L-Carnitin, which is needed for the fat burn in the musculature. Further it favours the resorption of iron in the small intestine.

Vitamin C is used also with and to the prophylaxis by colds. This application became in particular popular into the 1970er years by the Linus Pauling. A Metaanalyse of 55 studies shows however that, against the wide-spread faith, Vitamin cannot prevent C cold diseases. If necessary with humans, who - like some kinds of extreme haven - are exposed to strong physical efforts or extreme cold weather, Vitamin C seems to have an easily preventing effect. Nevertheless there is reference on the fact that the duration of a cold can be reduced by the Vitamin slightly (R. Douglas & H. PLoS Medicine, Bd. 2, No. 6, S. e168, 2005).

Recently Vitamin C is used also for the Vorbeugung and treatment of the travel sickness (Kinetosen). A scientific voucher for the use of this therapy is not in the literature however.

Occurrence

to the food Vitamin seems to C particularly in fruit, vegetable and green dte, its content sinks however with the kinds of preparing cooking, drying or a switches as well as during storekeeping. such as oranges, lemons and grapefruits contained - in ripe condition immediately after the harvest - much Vitamin C. green Kohl has the highest Vitamin C content of all kinds of Kohl (105-120 mg/100 g consumptionable substance). In Kohl vegetables ascorbic acid is bound in the form of Ascorbigen A and B. If the vegetable is cooked, the molecules disintegrate into L-ascorbic acid and Indol, so that it can contain C in cooked condition more Vitamin than in the raw condition. By to long cooking is however partly destroyed the Vitamin and delivered also into (usually verzehrte) the cook water. Red herb, white herb/sauerkraut are likewise Vitamin C suppliers (50 mg, 45 mg and/or 20 mg/100 g). One found the highest natural Vitamin C concentrations in Camu Camu and in Acerolakir. Many kinds of vegetable contain a Ascorbat Oxidase, which is activated in particular when cutting up. This leads e.g. with raw food, which verzehrt not immediately becomes, to substantial Vitamin C losses.

Vitamingehalt in mg per 100 g; these data serve only orientation. The actual values depend strongly on the local environmental condition in addition, the sort of the respective plants:

• Camu Camu 2000
• Acerolakir 1300-1700
• Hagebutte 1250
• Sand thorn berry 200-800
• Guave 300
• Black Johannisbeere 189
• Green Kohl 105-150
• Rosenkohl 90-150
• Paprika 100
• Ebereschenfrucht 98
• Spinach 50-90
• Kiwi 80
• Strawberry 50-80
• Lemon 53
• Orange (orange) 50
• Bilberry 22
• Pineapple 20
• Avocado 13
• Culture apple 12
• Banana 10-12
• Peach 10
• Pear 5

Need

In far parts of the world the supply of Vitamin C is relatively good, the daily requirement of an adult amounts to according to recommendation of the German society for nutrition 100 mg. The opinions concerning this go however far apart; the recommendations of other groupings lie between a fraction (z. B. and a multiples of this value (z. B. "„as much as possible "“). It stands firmly that quantities up to 5000 mg are considered briefly as harmless. Surplus quantities are separated by the body over the urine, since Vitamin is well water soluble C (see also Hypervitaminosen).

With a balanced mixing food can be assumed in Germany to the body all vitally necessary Vitamine, and therefore also Vitamin C in sufficient measure are supplied. The supply of Vitamin C is limited in Germany over the DGE recommendation of 100 mg per day. Therefore for healthy humans, who nourish themselves variedly and adequately, are redundant.

Investigations with 14C-markiertem Vitamin C show that the daily Ascorbatumsatz amounts to independent of the Vitamin C supply only about 20 mg. Thus already scarcely 20 mg are sufficient to avoid around scurvy.

For comparison purposes it is interesting that for guinea pigs a daily dose is recommended by 10-30 mg (with a weight of approx. 0.8-1.5 kg).

Articles in category "Ascorbic acid"

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