Definition of technical terms Chinese name: vitamin C English name: Vitamin C Other names: Ascorbic acid definition: the general name of compounds showing the biological activity of ascorbic acid. Ascorbic acid is a water-soluble vitamin, which is rich in fruits and vegetables. It plays a regulatory role in redox metabolic reaction, and the lack of it will cause scurvy. Applied disciplines: biochemistry and molecular biology (first-class disciplines); Hormones and vitamins (two disciplines) Vitamin C (ascorbic acid), also called L- ascorbic acid, is a water-soluble vitamin. Vitamin C in food is absorbed by the upper part of human small intestine. Once absorbed, it will be distributed to all water-soluble structures in the body. There is about 1500mg vitamin C in the vitamin C metabolism pool of normal adults, and the highest storage peak is 3000mg. Under normal circumstances, most vitamin C is decomposed into oxalic acid or combined with sulfuric acid to generate ascorbic acid -2- sulfuric acid, which is excreted in urine. The other part can be excreted directly through urine. Physical properties Appearance: Colorless crystal melting point: 190- 192℃ boiling point: (none) ultraviolet absorption maximum: 245nm fluorescence spectrum: excitation wavelength-no nm, fluorescence wavelength-no nm solubility: specific rotation of water-soluble vitamins: +20.5 to+21. :50-8 1-7EINECSNo。 : 200-066-2 molecular formula: C6H8O6 InChI code: Inchi = 1/C66. 4 (10) 6 (11)12-5/H2, 5,7-10h, 1H2/T2-, 5+/M0/s. . The dehydrogenation of hydroxyl groups on the five-membered ring of vitamin CC6H8O6 (vitamin C, ascorbic acid) +I2 (iodine) =C6H6O6 (dehydroascorbic acid) +2HI (hydrogen iodide) was tested. The synthesis of collagen needs the participation of vitamin C, so VC lacks foods rich in vitamin C to protect itself from the sun, and collagen can't be synthesized normally, leading to disorder of cell connection. The human body is composed of cells, which are connected by intercellular substance, and the key component of intercellular substance is collagen. Collagen accounts for 1/3 of the protein of the body, which generates connective tissue and constitutes the bones of the body. Such as bones, blood vessels and ligaments. , determine the elasticity of the skin, protect the brain, and contribute to the healing of human trauma. The strength of vascular wall in the treatment of scurvy has a great relationship with VC. Microvessel is the smallest of all blood vessels, and its wall may be only one cell thick. Its strength and elasticity are determined by collagen, which is responsible for connecting cells and has the function of cement. When VC is insufficient in the body, microvessels are easy to rupture and blood flows to adjacent tissues. When this happens on the skin surface, it will produce congestion and cyanosis; When it happens in the body, it can cause pain and joint swelling. In severe cases, bleeding of stomach, intestine, nose, kidney and periosteum may occur, and even death may occur. Prevent gingival atrophy and bleeding. A healthy chewing gum tightly wraps every tooth. Gingiva is soft tissue, which is prone to atrophy and bleeding when lacking protein, calcium and VC. Vitamin c is slightly acidic. As a micronutrient, it is ingested into the body. After being dissolved and digested in the body, its acidity and alkalinity have little effect on the human body, so it is not necessary to pay too much attention to its acidity and alkalinity. Vitamin C helps to consolidate cell tissue, help to synthesize collagen, strengthen bones and teeth, and prevent gum bleeding. Long-term use is harmless and beneficial to teeth and gums. Prevention of arteriosclerosis can promote the excretion of cholesterol, prevent cholesterol from depositing on the inner wall of arteries, and even dissolve the deposited atherosclerotic plaques. Antioxidants can protect other antioxidants, such as vitamin A, vitamin E, unsaturated fatty acids, etc., and prevent free radicals from harming the human body. Vitamin C(7 tablets) can reduce ferric iron which is difficult to be absorbed and utilized to ferrous iron, promote the absorption of iron in intestine, improve the utilization rate of iron in liver, and help to treat iron deficiency anemia. Anti-cancer rich collagen helps to prevent the spread of cancer cells; The antioxidant effect of VC can resist the damage of free radicals to cells and prevent cell variation; Prevent nitrite and secondary amine from forming strong carcinogen nitrosamine. Someone once dissected a patient who died of cancer and found that the VC content in the patient was almost zero. In human life activities, it is very important to protect cells, detoxify and protect the liver to ensure the integrity and normal metabolism of cells. Therefore, glutathione and enzymes play an important role. Glutathione is a short peptide composed of glutamic acid, cystine and glycine, which has redox effect in the body. It exists in two forms, namely oxidation type and reduction type, and reduction type plays an important role in ensuring the integrity of cell membrane. VC is a strong antioxidant, which reduces oxidized glutathione to reduced glutathione through its own oxidation, thus playing an antioxidant role. Enzymes are catalysts for biochemical reactions, and some enzymes need free sulfhydryl (-SH) to keep their activity. VC can reduce disulfide bond (-S-S) to -SH, thus improving the activity of related enzymes and playing an antioxidant role. As can be seen from the above, as long as VC is sufficient, VC, glutathione and -SH will form a powerful combination of anti-oxidation, scavenging free radicals, preventing lipid peroxidation and toxic effects of certain chemicals, and protecting the detoxification ability of the liver and the normal metabolism of cells. Improve human immunity. White blood cells are rich in VC, and when the body is infected, the VC in white blood cells decreases sharply. VC can enhance the chemotaxis and deformability of neutrophils and improve their bactericidal ability. Promote the generation of lymphocytes and improve the body's ability to identify and kill foreign cells and malignant cells. Participate in the synthesis of immunoglobulin. Improve the activity of complement esterase in CI and increase the production of complement CI. Promote the production of interferon, interfere with the transcription of virus mRNA, and inhibit the proliferation of virus. Improve the body's emergency ability. Abnormal stimulation, such as severe pain, cold, lack of oxygen, strong mental stimulation, etc., will trigger a state of tension for abnormal stimulation. This state is accompanied by a series of organisms, including sympathetic nerve excitement, adrenal medulla and increased secretion of corticosteroids. Adrenaline and norepinephrine secreted by adrenal medulla are converted from tyrosine, which requires VC. Edit the name of drug analysis method-scope of application for determination of vitamin C-redox titration in this paragraph. This method uses titration to determine the content of vitamin C. This method is suitable for vitamin C. Method Principle Add newly boiled cold water and dilute acetic acid to dissolve the sample, add starch indicator, immediately titrate with iodine titration solution (0.05mol/L) until the solution turns blue and does not fade within 30 seconds. Read the dosage of iodine titration solution and calculate the content of vitamin C. Reagent/kloc. Starch indicator solution 4. Glacial acetic acid solution equipment: sample preparation 1, iodine titration solution (0.05 mol/L) preparation: take iodine 13.0g, add 36g of potassium iodide and. Calibration: Weigh about 0. 15g of standard arsenic trioxide dried at 105℃, accurately weigh it, add 10 ml of sodium hydroxide titration solution (1 mol/L), dissolve it with slight heat, and add 20mL of water and 1 drop of methyl. . Every 1 ml of iodine (0. 1 mol/l) is equivalent to 4.946 grams of arsenic trioxide. According to the consumption of the solution and the amount of arsenic trioxide, the concentration of the solution is calculated. Storage: put it in a brown glass bottle with a glass stopper, seal it and place it in a cool place. 2. Take 0.5g soluble starch as starch indicator, add 5mL water, stir evenly, slowly pour into 100mL boiling water, stir while adding, continue to boil for 2min, cool, and pour out the supernatant. This liquid should be made in a new way. Operating Steps: Take 0.2g of this product, accurately weigh it, add 100mL of newly boiled cold water and 10mL of dilute acetic acid solution to dissolve it, add 1mL of starch indicator solution, titrate with iodine titration solution (0.05mol/L) immediately until the solution turns blue and does not fade within 30 seconds, and correct the titration result with blank test. Record the volume (mL) of iodine titration solution consumed. Every 1mL iodine titration solution (0.05mol/L) is equivalent to 8.806 mg of c6h8o6. Note 1: "accurate weighing" means that the weighing should be accurate to one thousandth of the weighed weight, and "accurate weighing" means that the accuracy of measuring the volume should meet the accuracy requirements of the volume pipette in the national standard. References Pharmacopoeia of People's Republic of China (PRC) and China, edited by National Pharmacopoeia Committee, Chemical Industry Press, 2005, Part II, page 669 This paragraph is suitable for 1, people who are prone to fatigue. 2. People who work in polluted environment. People with high vitamin C content in the body hardly absorb harmful elements such as lead, cadmium and chromium. 3. People who like smoking. Smokers eat more foods containing vitamin C, which helps to improve the resistance of lean tomatoes and oranges rich in vitamin C cells, maintain the elasticity of blood vessels and eliminate nicotine in the body. 4. People who engage in strenuous exercise and high-intensity labor. These people will lose a lot of vitamin C due to excessive sweating and should be supplemented in time. 5. Patients with scurvy. This disease is due to the lack of vitamin C in diet, which leads to poor formation of hoof tissue and increased brittleness of capillary wall. We should eat more foods rich in vitamin C. A person with spots on his face. Vitamin C has antioxidant effect, and vitamin C supplementation can inhibit the formation of pigment spots and promote their regression. 7. People who take drugs for a long time. Take aspirin, sleeping pills, anticancer drugs, tetracycline, calcium products, birth control pills, antihypertensive drugs, etc. , will reduce the body's vitamin C, causing other adverse reactions. Vitamin c should be supplemented in time. 8. Cataract patients. Vitamin C is a nutrient element of intraocular lens, and insufficient intake of vitamin C is one of the factors leading to cataract, so patients should take more vitamin C, and this paragraph is rich in food (in order of size). Grade food quantity (g) Vitamin C quantity (mg) 1 cherry 50 12 4502 guava 80 1 red pepper 8013 yellow pepper 80 1364. Three 1205 persimmons1501056 broccoli 6 1/4 967 strawberries 100 6 808 oranges1301. Three strains of 72 10 kiwifruit 100 1 68 are mainly used to improve immunity, prevent cancer, heart disease and stroke, and protect teeth and gums. In addition, taking vitamin C on time can also reduce skin pigmentation, thus reducing black spots and freckles and making skin fair. Foods rich in vitamin C include broccoli, green peppers, oranges, grape juice, tomatoes and so on. It can be said that all vegetables and fruits contain a lot of vitamin C. American experts believe that the optimal dosage of vitamin C per person per day should be 200 ~ 300mg, with a minimum of 60mg, and half a cup (about 100ml) of fresh orange juice can meet this minimum amount. The reference intake (RNI) of adults recommended by China Nutrition Society is 1000mg/ day, and the maximum tolerable intake (UL) is1000 mg/day. The recommended intake for normal needs is 1, adults and early pregnant women are 100 mg/d 2, pregnant women and lactating women are 130mg/d/d Note: Everyone's demand for VC varies greatly. Some people can be satisfied by adding a small amount, and some people can reach 10 gram or even higher every day. In the history of human research on vitamin C, Dr. Robert F.Cathcart discovered and established a set of standards for the use of vitamin C as early as the early 1970s. When a person takes vitamin C orally to a considerable amount, that is, 0.5~200 grams within 24 hours, slight diarrhea will occur due to the change of intestinal osmotic pressure. Cascade calls the amount slightly lower than this "intestinal tolerance of vitamin C", that is, the amount that a person can bear without causing slight diarrhea. Because acid-free VC makes it possible to take a large amount of vitamin C orally, then everyone can take it according to their own physical condition. As long as it is within the range of your own intestines, the effect will be very good. Interestingly, people's intestinal tolerance to VC varies. When the human body is sick, the intestinal tolerance will be greatly improved, such as the tolerance of 1 g at ordinary times, and the tolerance will be improved to varying degrees in acute infections, tumors, heart diseases and other chronic diseases, and even colds. Physiological function: 1, promoting the biosynthesis of collagen. Conducive to faster healing of tissue wounds; 2. Promote the metabolism of tyrosine and tryptophan in amino acids and prolong the life of the body. 3. Improve the utilization rate of iron, calcium and folic acid. 4. Improve the metabolism of fat and lipids, especially cholesterol, and prevent cardiovascular diseases. 5, promote the growth of teeth and bones, prevent gum bleeding, prevent joint pain, lumbago and leg pain 6, enhance the body's anti-stress ability and immunity to the external environment. 7. Antioxidants with strong water solubility mainly act on aqueous solutions in the body. 8. Strong connective tissue. 9, promote the synthesis of collagen, prevent gingival bleeding, main physiological function 1, participate in hydroxylation reaction. Hydroxylation is a necessary step in the synthesis or decomposition of many important substances in the body, and vitamin C must participate in the hydroxylation process. (1) promotes collagen synthesis. When vitamin C is deficient, collagen synthesis is impaired, leading to scurvy. ⑵ Promote the synthesis of neurotransmitters (5- hydroxytryptamine and norepinephrine). ⑶ Promote steroid hydroxylation. Patients with high cholesterol should be supplemented with sufficient vitamin C _ (4) to promote hydroxylation and detoxification of organic substances or poisons. Vitamin C can enhance the activity of mixed functional oxidase and enhance the detoxification (hydroxylation) process of drugs or poisons. 2. restore. Vitamin C can be oxidized or reduced in vivo, so it can be used as a hydrogen donor and a hydrogen acceptor and plays an important role in the redox process in vivo. High dimensional C fruit (7 pieces) (1) promoted antibody formation. High concentration of vitamin C helps to reduce cystine in food protein to cysteine, and then synthesize antibodies. (2) Promote the absorption of iron. Vitamin C can reduce the hard-to-absorb trivalent iron to the easily-absorbed bivalent iron, thus promoting the absorption of iron. In addition, it can also make sulfhydryl groups such as ferrous complexing enzyme active, thus playing an effective role, so vitamin C is an important auxiliary drug for the treatment of anemia. ⑶ Promote the formation of tetrahydrofolate. Vitamin C can promote the reduction of folic acid to tetrahydrofolate, so it also has a certain effect on megaloblastic anemia. ⑷ Keep the activity of sulfhydryl enzyme. 3. Detoxification. Supplementing a large amount of vitamin C in the body can reduce the toxic effects of heavy metals such as lead, mercury, cadmium and arsenic on the body. 4. Prevent cancer. Vitamin C can block the synthesis of carcinogen N- nitroso compounds and prevent cancer. 5. Scavenging free radicals. 6. Synergy. Vitamin C, tocopherol and reduced coenzyme ⅱ can synergistically scavenge free radicals in vivo. A survey shows that increasing the intake of fruits and vegetables a little every day may play a role in preventing diseases. Vitamin c may have a protective effect on some chronic diseases. However, from the prospective research results, the relationship between vitamin C and cardiovascular disease or cancer is not consistent. In order to evaluate the relationship between plasma vitamin C level and mortality of various causes (cardiovascular disease, ischemic heart disease and cancer), Khaw et al. of the School of Clinical Medicine, Cambridge University, UK conducted a four-year prospective survey on 19496 adults aged 45-79. (Lancet 200 1, 357∶657), and the subjects were included to fill out the health and lifestyle questionnaire and receive physical examination. The researchers tracked the cause of death for four years. These people were grouped according to sex-specific plasma vitamin C5 quantile. Cox proportional hazard model is used to determine the effects of vitamin C and other risk factors on mortality. The results showed that the concentration of vitamin C in plasma was negatively correlated with the mortality of both sexes caused by various reasons, including cardiovascular diseases and ischemic heart diseases. The risk of death in the quintile with the highest vitamin C content is half that in the quintile with the lowest vitamin C content (P