Author: Site Editor Publish Time: 2021-05-27 Origin: Site
Vitamin C, also known as vitamin C, is a polyol with the chemical formula C6H8O6. The structure is similar to glucose, and the two adjacent enol hydroxyl groups in the second and third positions in the molecule are easily dissociated to release H+, so it has the properties of acid, also known as L-ascorbic acid. Vitamin C has a strong reductivity and can be easily oxidized to dehydrogenation ofvitamin C, but the reaction is reversible, and ascorbic acid and dehydroascorbic acid have the same physiological function. However, if dehydroascorbic acid continues to be oxidized to generate diketone accompanied sugar acid, the reaction is irreversible and the physiological effect is completely lost.
Name: Vitamin C
Nickname: L-ascorbic acid，Vitamin C，2,3,5, 6-tetrahydroxy 2-hexene-4-lactone
Chemical formula: C6H8O6
Molecular Weight: 176.13
CAS login number: 50-81-7
EINECS login number: 200-066-2
Melting point: 190 to 192 ℃
Boiling point: 553 ℃
Density: 1.694 g/cm³
External view: white crystalline or crystalline powder, odorless, sour taste
Flashpoint: 238.2 ℃
Safety Description: S24/25
Danger symbol: R20/21/22
Hazard description: XN
Vitamin C has an enediol structure, a lactone ring and two chiral carbon atoms. Therefore, vitamin C is not only active, but also has optical activity.
Vitamin C for white crystal or crystalline powder, odorless, sour taste, long - time color gradual yellow. Soluble in water, acidic, slightly soluble in ethanol, insoluble in chloroform or ether.
The molecular structure of vitamin C has an enediol structure. Due to the influence of conjugate effect, the acidity of C2-OH is very weak (PK2 =11.57), while the acidity of C3-OH is strong (PK1 =4.17). Therefore, vitamin is generally manifested as monoacid, which can react with sodium bicarbonate to form sodium salt.
The molecular structure of vitamin C contains two chiral carbon atoms, so it has optical activity. According to law determination (CHP2015 General Rule 0621), the specific curl of aqueous solution containing 0.10g/mL of this product is +20.50°~+21.50°.
The enediol group in the molecular structure has strong reductivity and is easily oxidized to diketone group to become dehydroascorbic acid. Dehydroascorbic acid can be further hydrolyzed in alkaline solution or strong acid solution to form diketogulonic acid and is inactivated.
Hydrolysis of sex
The action of vitamin C with sodium carbonate produces monosodium salts, which do not hydrolyze. The double bonds stabilize the lactone ring, but in strong alkaline solutions, the lactone ring hydrolyzes to form keto acid salt.
Properties of sugars
Vitamin C is structurally similar to sugar and thus has the properties of carbohydrate reactions.
Vitamin C molecules have conjugated double bonds, and its dilute hydrochloric acid solution has the maximum absorption at 243nm, but under neutral or alkaline conditions, it is redshifted to 265nm.
Vitamin C for antibodies and collagen formation, tissue repair (including some REDOX function, metabolism of phenylalanine, tyrosine, folic acid, iron, carbohydrate, fat, protein synthesis, maintain immune function, hydroxyl serotonin, full blood vessels, promote the heme iron absorption and so on necessary, at the same time also has antioxidant, vitamin C Anti-free radical, inhibit the formation of tyrosinase, so as to achieve whitening, light spot effect.
In human body, vitamin C is a highly effective antioxidant, which is used to reduce the oxidative stress of ascorbate peroxidase SCH. Vitamin C is also needed in many important biosynthetic processes.
Since most mammals rely on the liver to make vitamin C, there is no shortage of it; But a few animals, such as humans, primates, and marmots, cannot synthesize them on their own and must be ingested through food, drugs, etc.
Vitamin C can be oxidized or reduced in the body, so it can be used as a hydrogen donor or acceptor, and plays an important role in the process of REDOX in the body.
1. Promotes antibody formation. High concentrations of vitamin C help the cystine in food proteins to be reduced to cysteine, which in turn makes antibodies.
2. Improves iron absorption. Vitamin C can make difficult to absorb iron reduction to absorb iron, thus promoting the absorption of iron. In addition, still can make the sulfhydryl group in active state, in order to effectively play a role, so vitamin C is the important adjutant medicine that treats anemia.
3. Promotes tetrahydrofolate formation. Vitamin C can promote folate reduction into tetrahydrofolate after play a role, so it has a certain effect on megaloblastic anemia.
4. Maintain the thiol enzyme activity.
5. Detoxification. A large number of vitamin C supplements can alleviate the toxic effects of heavy metals such as lead, mercury, cadmium and arsenic on the body.
6. Prevention of cancer. Many studies have shown that vitamin C can block the synthesis of cancer-causing N-nitroso compounds and prevent cancer.
7. Free radical scavenging. The tocopherol free radical is reduced to tocopherol, and the ascorbic acid free radical generated by the reaction can be reduced to ascorbic acid under certain conditions under the action of NADH2 system enzyme
Food Source Editor
Dietary sources of vitamin C are widely found in fresh vegetables and fruits. Tomatoes, cauliflower, bell peppers, dark leafy vegetables, bitter melon, citrus, grapefruit, apples, grapes, kiwi, fresh dates are rich in vitamin C.
Intake of vitamin C is usually absorbed in the upper small intestine (duodenum and upper jejunum), and only a small amount is absorbed by the stomach, with a small amount also absorbed by the mouth mucosa. Unabsorbed vitamin C will be directly transferred to the large intestine, no matter how much vitamin C sent to the large intestine, will be decomposed into gas substances by intestinal microorganisms, without any effect, so the body's absorption capacity is fixed, more intake is equal to more waste.
The metabolic process and conversion mode of vitamin C in the body are still inconclusive, but it can be confirmed that the final metabolite of vitamin C is excreted by urine. If the concentration of vitamin C in the urine is too high, it can reduce the pH in the urine and prevent bacterial breeding, so it has the effect of avoiding urinary tract infection.
Vitamin C is an important cofactor in a variety of enzyme reaction pathways in the body, and the main dietary sources are fresh vegetables and fruits. The link between vitamin C and urinary calculi has been controversial. On the one hand, vitamin C is partially converted into oxalate in the body, resulting in increased urinary oxalate excretion and increased risk of calcium oxalate stone formation. On the other hand,Vitamin C can remove free radicals, reducing oxidative stress, and oxidative stress can cause renal tubular damage, so as to facilitate the formation of high in patients with urinary oxalate stones. Therefore, some researchers believe that supplementation of small doses of vitamin C will not promote the formation of calcium oxalate stones, but also can prevent the occurrence of urinary calculi.