Vitamin C and P

. The nameVitamin C, also known as ascorbic acid, is a polyol containing an endolipid structure characterized by an oleol-type hydroxyl that dissociates H-plus, so its aqueous solution has a strong acidity. Vitamin C can be dehydrogenated and oxidized, has a strong reducing properties, oxidizing vitamin C (dehydrogenated ascorbic acid dehydroascorbic acid) can also accept hydrogen and be reduced.vitamin C contains asymmetric carbon atoms, has optical isomer, the natural existence, physiological activity is L-type astrophic acid.Vitamin C is more stable in acidic aqueous solutions (pH<4), easy to be destroyed in neutral and alkaline solutions, and more susceptible to oxidation and decomposition when trace metal ions
(e.g. Cu, Fe, etc.) are present
; In addition, plant
tissue
still contains assailtic acid oxidase, can catalyz asseptic acid oxidation and decomposition, loss of activity, so vegetables and fruits stored for too long, where vitamin C can be destroyed and its nutritional value reduced.most animals are able to use glucose to synthesize vitamin C, but humans, primates and guinea pigs cannot synthesize vitamin C because they lack enzymes to synthesize vitamin C and must rely on food supplies. Vitamin C in food can be quickly absorbed from the gastrointestinal tract, after absorption of vitamin C widely distributed in the body's tissues, with the highest levels in the adrenal glands. But vitamin C is rarely stored in the body and must often be supplied with food. Vitamin C breaks down in the body to produce lysic acid and suasaccharide.vitamin C has a wide range of physiological effects, in addition to the prevention and treatment of scum disease, there are many clinical applications, from colds to cancer, vitamin C is the most widely used vitamin. However, some of its action is not very clear, from the dosage used, there is a growing trend beyond the concept of vitamins, but as a health care drug used.vitamin C is known to be involved in metabolic function in the body in the following areas.(i) Participating in the hydroxygenation reaction in the bodyVitamin C plays an important role in the hydroxy reaction of many substances, and hydroxylation reaction is a necessary step in the synthesis or decomposition of many important compounds in the body, such as the production of gels, synthesis and transformation of steroids, as well as the biological transformation of many
organic
drugs or poisons, etc., all need hydroxylation to complete.. 1. Synthesis of gelsWhen collancg is synthesized, proline (Pro) and Lysine residues in the
peptide
chain need to be hydroxygenated into hydroxy proline and hydroxylycline residues, respectively (see Chapter 15). Vitamin C is one of the necessary auxiliary factors for this hydroxy reaction, because in the hydroxycodyme, not only the corresponding hydroxyase, but also O2, Fe, and a-ketone diacid, vitamin C helps to maintain the reduced state of Fe, and can activate hydroxyase.Collagen is an important component of intercellular quality, therefore, when vitamin C is deficient, collagen and intercellular synthesis disorders, capillary wall brittleness increased, permeability increased, minor trauma or pressure can cause capillaries to rupture, causing bleeding, clinically known as scurvy.. 2. Steroid hydroxylationNormally, about 80% of cholesterol in the body is converted into bile acid after discharge, before cholesterol is converted to bile acid, the ring part of hydroxysis (7 alpha hydroxy, see cholesterol metabolism), and then the later side chain breaks, eventually producing bile acid, vitamin C deficiency is blocked, cholesterol into bile acid effect decreased, liver cholesterol accumulation, and blood cholesterol concentration increased. Therefore, clinical use of a large amount of vitamin C can reduce blood cholesterol, the rationale may be that vitamin C promotes the transition of cholesterol to bile acid.addition, when the adrenal cortogen
mones
synthesis is strengthened, vitamin C levels in the corties decrease significantly, which may be the consumption of vitamin C during some oxycodone synthesis steps.. 3. Aromatic
amino acid
hydroxyphe hydroxy into tyrosine (Tyr), tyrosine into catecholamine (catecholamine) or decomposing into uric acid and many other processes require vitamin C participation. Vitamin C (see chapters such as amino acid metabolism and neurobiometry
biopics
) is also required when tryp is converted to 5-serotonin (5-HT), and both cervixolamine and 5-serotonin are important neurotransmitter, which play an important role in regulating nerve activity. . 4. The hydroxylation process of organic drugs or poisons drugs or poisons on the endotogenous web is an important biorecommesis reaction, when vitamin C is lacking, the hydroxylation reaction decreases significantly, the metabolism of the drug or poison slows down significantly, after giving vitamin C, the enzyme system activity that catalytics such hydroxychemical reactions increases, and promotes metabolic transformation of the drug or poison, thus enhancing the role of detoxification (see the biodegradation in the chapter on liver biochemistry). (ii) reduction effect vitamin C in the body as an important reducing agent and play a role, mainly in the following areas. . 1. Protecting -based and making -based regeneration Many enzymes containing -basis are known to require free H when they act as catalytic in the body, while vitamin C keeps the enzyme molecule -SH in a reduced state. In order to maintain a certain activity of the enzyme, vitamin C can also restore the oxidized glutathione (G-S-G) to the prototype glutathione (G-SH), so that -SH can be regenerated, thus ensuring the function of glutathione. For example, unsaturated lipidic acid is easily oxidized into lipid peroxide, which can make various cell membranes, especially lysosome membrane rupture, release a variety of hydrolyzed enzymes, resulting in self-dissolving tissue, resulting in serious consequences, but also prototype glutathione in glutathione peroxidase catalysis can make lipid over Oxide reduction eliminates its destructive effect on tissue cells, while G-SH is oxidized to G-S-S-G, and vitamin C can also restore G-S-S-G to G-SH, which is continuously replenished by glutathione reductase catalysis. Figure 3-6 Relationship between vitamin C and glutathione laxative reduction reaction (1): G-SH reductase (2): G-SH peroxidase and then, as some enzymes containing -based enzymes are inhibited in metal poisoning (e.g. lead poisoning), giving a large amount of vitamin C can often reduce its toxicity. Metal ions are thought to bind to H enzymes in the body, causing them to insulate, causing metabolic disorders and poisoning. Vitamin C restores G-S-S-G to G-SH, which binds to metal ions and excretes the body, so vitamin C protects -based enzymes and has a detoxifying effect. Figure 3-7 Vitamin C Detox Map 2. Promotes the absorption and utilization of iron Vitamin C can reduce the hard-to-absorb Fe-C into an easy-to-absorb Fe-plus, promote the absorption of iron, and it can also promote the reduction of fe-plus in the body, which is conducive to the synthesis of hemolyxin. In addition, vitamin C has the effect of directly reducing high iron hemoglobin (MHb). . 3. Promoting the transformation of folic acid into tyhydroflytic acid (see before) It can be seen that vitamin C can be complementary to the treatment of iron deficiency anemia and pyrethroid anemia. . 4. the production of
antibody
antibody molecule contains a considerable number of double S bonds, so the synthesis of antibodies need a sufficient amount of cysteine, the body's high concentration of vitamin C can reduce cysteine into cysteine, conducive to the synthesis of antibodies. Vitamin C enhances the body's immune function is not limited to promoting the synthesis of antibodies, it can also enhance the response of white blood cells to influenza viruses and promote the bactericidal action of H2O2 in granulocytes. vitamin P, also known as permeable vitamin (P for permeability), was originally isolated from lemons and chemically flavonone, also known as citrin. Later found a variety of substances with similar structure and activity, so vitamin P is not a single compound, the main vitamin P compounds are orange pyridine, fennel (reedin) and L-table tea. main physiological effect of vitamin P is to maintain the normal permeability of capillaries wall, and the permeability is enhanced without it. Because vitamin P often coexists with vitamin C in nature, it is generally believed that sepsis is the result of a common deficiency of these two vitamins. Although the disease of vitamin P deficiency has not been found in human beings, vitamin P can be used clinically to prevent and treat some diseases caused by the increased permeability of capillaries. The mechanism of vitamin P has not been clarified, and experiments have shown that it has the effect of "saving" vitamin C and inhibiting hyalurino acidase (see Chapter 17).
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