What is Chitosan?
ChitosanIt is obtained by deacetylation of chitin, which is widely present in nature. Chitosan is recognized by the international scientific community as the sixth indispensable life element of the human body after proteins, fats, sugars, minerals and vitamins.
Research and application of chitosan
as a drug carrier[1].
Chitosan has structural characteristics similar to glucosamine, and it has great superiority as a drug carrier. Chitosan as raw material of pharmaceutical excipients has a variety of functions, such as: suspension aid, adhesive, etc. Studies have shown that the amino content and relative molecular weight of chitosan have an important impact on antimicrobial activity [2].
Carrier drugs, also known as polymer drugs, refer to drugs made by implanting small molecule drugs on the molecular chain of specific polymer materials. When the drug molecules are continuously hydrolyzed from the polymer chain, or the polymer chain is completely degraded, the drug properties are slowly released, and the pharmacological effect of the drug can be maintained for a long time.
Chitosan membrane is non-toxic, can be taken internally, without any *** and can be used as an ideal drug sustained-release membrane material, chitosan is made into a gel, the drug is surrounded by it, they are implanted in the human body after the erosion sustained release, that is, the surface polymer material absorbs water and expands and forms a gel, so that the water molecules can not quickly enter the interior to dissolve the drug, only when the water molecules can enter the inside, the drug can be slowly dissolved, until the drug is released completely.
Chitin and chitosan as sustained-release agents can control the release of the drug, and the blood concentration is stable and kept within the effective concentration range, prolonging the effective time without toxicity. This is due to the fact that chitosan particles can gradually swell and can float to form gels, especially in acidic solutions (pH1 2), while most sustained-release polymers can only form gels at high pH values. Therefore, extended-release agents made of chitosan can prolong the residence time in the gastrointestinal tract, thereby improving the bioavailability of the drug.
Membranes and dressings for pharmaceutical use[4].
Chitosan has excellent biocompatibility and is an excellent biomedical material, which can be made into a variety of film-like dressings [4]. Among them, the non-woven fabric made of chitosan acetic acid solution is used for large-scale burns and scalds because of its excellent air permeability and water permeability, and the effect is good. Studies have shown that the preparation of wound covering film with chitosan has good biosolubility and antiviral properties, and can promote wound healing. Sutures made of chitosan fibers [4] have strong tensile strength for a predetermined period of time and have good adaptability in the body, and after a period of time, chitosan sutures can be degraded by lysozyme and absorbed by the body without the need to remove sutures. Due to its sufficient strength, chitosan membrane can penetrate water-soluble organic matter such as urea and muscle liver, and has good water permeability, which can replace various renal dialysis membranes made by the current cupammonia method.
Chitosan and fatty liver[2].
Animal experiments have shown that chitosan can significantly reduce the severity of liver steatosis in rats with experimental fatty liver disease, and the degree of improvement gradually increases with the increase of drug dosage [2]. These results indicated that chitosan could lower blood lipids and cholesterol, and had a certain preventive effect on the formation of fatty liver. Studies have also shown that chitosan may also play its role in protecting the liver and reducing steatolesions by repairing the structure and function of mitochondria, improving the energy metabolism of tissues, and promoting the oxidative decomposition of fatty acids.
Chitosan derivatives
Because chitosan is biodegradable in the human body and non-toxic, its use has attracted great attention and interest from the pharmaceutical community. However, due to the insoluble nature of chitosan in water, its role is limited to a certain extent, so many experts and scholars have further focused on the research and development of chitosan derivatives.
With the deepening of research, more and more types of chitosan derivatives have been revealed and developed, and their roles have been increasing.
Research and application of chitosan derivatives
Antibacterial and antiseptic effects[5].
The acidic aqueous solution of chitosan solution and chitosan itself has antibacterial and antiseptic effects, but chitosan is insoluble in water, which limits its application. If chitosan is chemically modified, water-soluble chitosan such as carboxymethyl chitosan can be generated [5]. In the experiment, it was found that carboxymethyl chitosan had no inhibitory effect on common burn infection pathogens, while carboxymethyl chitosan silver had both wound healing and antibacterial properties. Experiments proved that silver carboxymethyl chitosan had inhibitory effects on Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, and the antibacterial efficiency was respectively. 2% and 75%.
Chito-oligosaccharides are associated with blood glucose[6].
Chito-oligosaccharides are degradation products of chitosanChitosan is a kind of biological polymer polysaccharide, but due to the relatively large molecular weight of chitosan, it cannot be directly soluble in water, and its application is limited to a certain extent. If the chitosan molecule is degraded by appropriate methods, oligomers that can be directly soluble in water and have more advantages than chitosan are obtainedChito-oligosaccharides
Studies have found that normal intestinal flora is associated with diabetes, such as clinical use of Bifidobacterium can improve diabetes mellitus [6].
Experiments have proved that chito-oligosaccharides can promote the proliferation of beneficial microflora such as Bifidobacterium, improve the imbalance of intestinal flora, and enhance the anti-destruction ability of pancreatic B cells, thereby regulating blood sugar and improving diabetes symptoms. Moreover, chito-oligosaccharides have the characteristics of refreshing sweetness, good water solubility, and can be degraded in living organisms, which can be used as a food additive for diabetic patients, and may play a certain role in adjusting the intestinal flora**diabetes [7].
Chito-oligosaccharides and tumors[8].
Experiments have proved that oligosaccharides and oligosaccharides below 10 sugars can significantly improve the cellular immune function of the body, and have inhibitory effects on Lewis lung cancer and B16 melanoma [8], and the mechanism is mainly due to the hydrolysis of chitosan D-2-glucosamine has a significant killing effect on some cancer cells in vivo, and has almost no effect on normal tissues, so chitosan and its oligosaccharides can be used as chemotherapy drugs. 
Summary
Chitosan has great advantages as a drug carrier, which can effectively solve the problem of gastrointestinal tract by reducing the stimulation of drugs on the human gastrointestinal tract, and has been further applied as a natural preservative in inhibiting bacterial reproduction.
However, there is a lot of room for further research on the development and utilization of its role, the optimal state of various roles, and related data. Chitosan has a large molecular weight and cannot be directly soluble in water. It was found that the chemically modified chitosan derivatives and degraded oligosaccharides had good water solubility, and as an additive, the various effects of chitosan were not reduced, but also many unique functions were added.
Article**: Liu Changlan, Li Chengbin, Cui Wenxin. Application of chitosan in the field of medicine[J].Shandong Science, 2003, 016(003):68-71doi:10.3969/j.issn.1002-4026.2003.03.016.References:
1] Ran Xu, Gou Li, Meng Xianwei, et al. Preparation of chitosan solution and study on the degradability of chitosan[J].Food Sci, 2001, 22(7): 18221
2] Qi Xiaohong, Jiang Li, Li Xiaoyu, et al. Stereological analysis of chitosan on liver and mitochondria of experimental fat rats[J] Chin J Biochem Drug,2001,22(1):8210
3] Dong Xuechang, Yang Yanbing. New trends in the application of chitin and chitosan[J] Journal of Yunnan University for Nationalities, 2002, 11(1): 5662584
4] Liu Liu. Application of chitin and chitosan in the field of medicine[J].Liaoning Chemical Industry, 2001, 30 (12): 5372540
5] Zhan Xuejun, Xiong Yuanzhen. Study on the synthesis of carboxymethyl chitosan silver and its antibacterial experiments[J].Chin J Biochem Pharm, 2001, 22(3): 1422144
6] Ren Lin, Li Bangliang, Gao Shiying, et al. Effect of chito-oligosaccharides on blood glucose and intestinal microbiota in diabetic mice[J] Chin J Biochem Drug, 2001, 22(5): 2272229
7] Yan Rui Wang Xuan. Water-soluble polymers[ M].Beijing: Chemical Industry Press, 1999
8 ] Academician Huang Baotong and Professor Du Yumin. Speaker at the 2002 Large Symposium of the Chitin Society of the Chinese Chemical Society.
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