After deacetylation of chitin C2, 2- amino -2- deoxy -D- glucose polymer is formed. The higher the deacetylation degree, the better the functionality. But due to incomplete deacetylation, chitosan is actually a mixture of chitin and chitosan. Japan stipulates that chitosan should contain chitosan >: 85%. In the process of acid-base treatment, some glycosidic bonds of chitin are broken at 1 4, which reduces the degree of polymerization, and the degree of polymerization is in the range of 2-7 (7-8 is the best). There are two isomers of chitosan with an average molecular weight of 65438+200,000. It is a soft powder from beige to reddish, odorless, and its water content is about 60%. Soluble in dilute HCL and HAC, the viscosity of 10% dilute HAC solution is 2000-3000CPS, and the maximum ultraviolet absorption peak is196 mm. Soluble in binary organic solvents (such as CH2CL2-TCA, CH2CLCH2CL-TCA, etc. ). Because its molecule contains -NH2 and primary and secondary -OH multifunctional groups, it can undergo many chemical reactions such as etherification, esterification, crosslinking and chelation.
Chitin is a strange name for human beings, which widely exists in the shells of lower plants and crustaceans. The earliest utilization of crustacean resources by human beings began in the famous Compendium of Materia Medica, which records that crab shells have the function of breaking blood stasis and promoting digestion. The word "crab" itself refers to an insect that detoxifies. 18 1 1 year, French scholar Blano first discovered chitin in mushrooms, and since then, human beings have started a long research and application. Chitosan is also called chitin, chitosan, chitin and the sixth element. Widely found in the stems and leaves of shrimp, crabs, insects and plants.
Chitin, also known as chitin and chitosan, is a kind of high molecular polysaccharide with similar chemical structure to fiber, which is widely found in the hard shell of insects, crustaceans and the cell wall of fungi. In recent years, researchers have studied chitin and its derivatives, providing a lot of valuable information and showing its broad application prospects. This paper briefly introduces the application of chitin in medicine to promote the development and utilization of this resource.
First, the pharmacological effects of chitin
1. Antibacterial and anti-infective Chitin and its derivatives all have anti-infective effects in different degrees, among which chitin hexose has the strongest effect. Chitosan with small molecular weight has protonated ammonium, which interacts with the negatively charged cell membrane of bacteria, adsorbs and aggregates bacteria, and at the same time penetrates the cell wall and enters cells, disrupting the metabolism and synthesis of bacteria, thus playing an antibacterial role. Xia Wenshui and Wu Yannan believe that deacetylated chitin with relative molecular weight of 1500 has the strongest inhibitory effect on Escherichia coli, and the antibacterial effect decreases with the increase of molecular weight. Zheng Guanghua found that deacetylated chitin has a strong inhibitory effect on Staphylococcus aureus, Escherichia coli, yersinia enterocolitica, Salmonella from mice and Listeria monocytogenes. Professor Wu Qingji of China Textile University has successfully made chitin into non-woven fabrics, cast films, coated gauze and other medical dressings for clinical use. Among them, the nonwoven fabric made of chitin and acetic acid has excellent air permeability and water permeability, and has good anti-infection and wound healing effects on large-area burns and scalds. At present, Shanghai can produce about 100 tons of chitin medical materials every year.
2. Reducing blood lipid and preventing arteriosclerosis Tao Wei and others fed rats with synthetic feed containing 1% cholesterol and 0.2% sodium deoxycholate for 28 days. At the same time, they induced hyperlipidemia and observed its effect on hyperlipidemia by taking chitosan orally. The experiment set up a high-fat control group and three experimental groups with low, medium and high doses. The results showed that compared with the high-fat control group, the contents of total cholesterol and total triglyceride in the middle and high-dose chitosan groups decreased by 65438 00.5% and 65438 04.2% respectively, while the latter decreased by 65438 08.8% and 26.65438 0% respectively. Compare high density lipoprotein cholesterol and high fat in low, medium and high dose groups. Gu Yun et al. conducted an oral deacetylated chitin lipid-lowering test on 3 1 adult hyperlipidemia patients. After 30 days, cholesterol and triglyceride decreased, low-density lipoprotein cholesterol decreased, and high-density lipoprotein cholesterol and lipoprotein did not change significantly.
3. Antivirus Many scientists have confirmed the antiviral activity of chitin sulfate from many aspects. Derek Horton et al. proved that chitin derivatives containing SO42- on the amino group had a significant inhibitory effect on blood virus. Vorcellotti et al. found that sulfonated derivatives of chitin can inhibit viral infection in mammals, especially HIV infection, and the IC50 of inhibiting its replication is 7 μ g/ml, which also inhibits Roche leukemia virus and herpes simplex virus.
4. Chitin has excellent anti-tumor activity, especially chitin hexaglycan has strong anti-tumor effect. Professor Okuda of Ehime University in Japan confirmed through experiments that chitin can enhance the killing effect of lymphocytes on cancer cells at the concentration of 64 μ g/ml. Sheng Mao Suzuki reported that chitosan can directly inhibit Ehrlich ascites cancer cells. 0.5 mg/ml chitosan was added to the cancer cell solution containing 1× 105, and the cancer cells died completely after 24 hours. Saiki I reported that chitin sulfate and carboxymethyl chitosan sulfate have obvious inhibitory effects on melanoma tumor cells in a dose-effect relationship. Liu of Fujian Normal University inoculated S 180 tumor cells into mice, and established control group and chitin experimental group. Experiments show that chitosan has obvious inhibitory effect on S 180 mouse cancer cells. At present, researchers at home and abroad are very concerned about its anti-tumor effect.
5. Anticoagulant Muzzarelli and others fully realized that the chemical structure of chitin sulfate was similar to heparin in 1950s and 1960s, which indicated that this kind of compound had anticoagulant activity. Hirano reported in 1985 that the anticoagulant activity of O- disulfate chitin with molecular weight of 26,000 and O- is 2.2 times that of heparin (174 unit/mg).
6. Other Zhang Guiying has proved that chitosan has good radiation resistance. Li Jiang and other studies show that chitosan can protect the liver and improve its antioxidant capacity. Gao Fenglan of Shenyang Railway General Hospital treated 5 cases of angina pectoris, 4 cases of arrhythmia and 4 cases of refractory heart failure with oral deacetylated chitin, all of which received satisfactory results. In addition, some chitin derivatives can bind Fe2+ and enhance the absorption function of gastrointestinal tract, which can be used to treat iron deficiency.
7. Since the discovery of chitin for more than a century, people have always regarded chitin as waste, because chitin is insoluble in organic solvents such as water, dilute acid and dilute alkali, and the development cost is much higher than that of directly using cellulose. With the growth of human wisdom and the development of science and technology, it is found that chitin has characteristics that cellulose does not have, and it is the only edible animal fiber containing cations in the world. It is also the sixth life factor after protein, sugar, fat, vitamins and minerals. After chemical or biochemical treatment, crustaceans produce substances soluble in dilute acids-chitin and derived polysaccharides, which can be used in industrial fields (such as replacing plastics), agricultural fields (no pesticides and fertilizers) and cosmetic fields (skin conditioning, etc.). ), medicine, membrane materials and other environmental protection and health fields. After more than 20 years of continuous research and clinical experiments, miracles are constantly emerging. It can not only inhibit cancer, liver disease and diabetes, lower cholesterol, but also enhance human immunity and prevent aging. Because of its great economic value, it is widely used in medicine, food, industry and other fields at home and abroad. At present, this technology in China has reached the international advanced level.