Chitin is a rare positively charged dietary fiber in nature. Among natural organic compounds on Earth, cellulose is the most abundant, followed by chitin, with an estimated 10 billion tons of chitin biosynthesized annually in nature. Chitin is the most abundant nitrogen-containing organic compound on Earth, followed by protein.
Chitin is found in the cells of lower plants such as fungi and algae, the exoskeletons of arthropods like shrimp, crabs, and insects, and the cell walls of higher plants. It is an animal-based high molecular weight cellulose extracted from crab and shrimp shells using genetic engineering and is acclaimed by the scientific community as the "sixth life element"! Consequently, it has been recognized by governments in Europe, America, and China as a functional immune substance. Trace amounts of "chitosan" are also found in plants like Reishi and Cordyceps, but the content is only between 2% and 7%.
Chitin. Chitin was discovered in 1811 by French scholar Braconno and extracted from the exoskeletons of arthropods by Odier in 1823, who named it CHITIN, translated as Chitin. Appearance and properties: Light beige to white, soluble in concentrated hydrochloric acid/phosphoric acid/sulfuric acid/acetic acid, insoluble in alkali and other organic solvents, and also insoluble in water. The deacetylated derivatives of chitin (Chitosan derivatives) are soluble in water. Chitin has anti-cancer properties, inhibits the metastasis of cancer and tumor cells, enhances human immunity, and has liver-protecting and detoxifying effects. It is particularly suitable for diabetes, liver and kidney diseases, hypertension, obesity, and other conditions, and helps prevent cancerous cell changes and assist in radiotherapy and chemotherapy for tumor diseases.
Chitin is a rare positively charged dietary fiber in nature. Among natural organic compounds on Earth, cellulose is the most abundant, followed by chitin, with an estimated 10 billion tons of chitin biosynthesized annually. Chitin is the most abundant nitrogen-containing organic compound on Earth, followed by protein. These two points alone are sufficient to illustrate the importance of chitin. Crab shells contain 40% protein, 30% calcium, and 30% chitin. The process for extracting chitin is as follows: first, proteins are removed using a dilute sodium hydroxide solution, then calcium salts are removed using hydrochloric acid, and what remains is chitin. To remove the acetyl groups from this chitin, it is reacted with concentrated sodium hydroxide at high temperatures for a long period to produce chitin containing amino groups. Because chitin is insoluble in acids, alkalis, and water, it is difficult for the human body to utilize it. After deacetylation to form chitosan, it becomes soluble in dilute acids and body fluids and can be utilized by the human body.
Chitin Name Summary
Common names: Chitin, Chitosan (after deacetylation). English name: Chitin. Chinese name: Chitin. Chemical name: β-(1→4)-2-acetamido-2-deoxy-D-glucose.
Aliases: Chitin, Chitosan, Arthropodin, Poly-N-acetylglucosamine.
Molecular formula and molecular weight: (C8H13NO5)n (203.19)n.
Properties: Appears as an off-white amorphous substance, odorless and tasteless.
It can be dissolved in dimethylacetamide containing 8% lithium chloride or concentrated acids; it is insoluble in water, dilute acids, alkalis, ethanol, or other organic solvents.
In nature, chitin is widely found in the exoskeletons of arthropods such as lower plants, fungi, shrimp, crabs, insects, and in the cell walls of higher animals.
It is a linear high molecular weight polysaccharide, i.e., a neutral mucopolysaccharide. If treated with concentrated alkali to remove the acetyl groups, it becomes deacetylated chitosan. Chemically, chitin is inert, does not change with body fluids, does not cause a foreign body reaction in tissues, is non-toxic, and has characteristics such as antithrombotic and high-temperature resistance. Deacetylated chitosan is a basic polysaccharide that has acid-neutralizing and anti-inflammatory effects and can lower cholesterol and blood lipids.
Chemical Structure
Pure chitin is a non-toxic, odorless, white or grayish-white translucent solid that is difficult to dissolve in water, dilute acids, dilute alkalis, and common organic solvents, which limits its application and development. Later, in research and exploration, it was found that when chitin is treated with concentrated alkali to remove its acetyl groups, it becomes soluble chitin, also called chitosan or chitosan. Its chemical name is (1→4)-2-amino-2-deoxy-β-D-glucose, or simply polyglucosamine. This chitosan, due to the large number of amino groups in its macromolecular structure, greatly improves the solubility and chemical activity of chitin, thus giving it extensive application value in medicine, nutrition, and health care. Chitin is an extremely abundant natural resource on Earth and is the only animal fiber found in nature to carry a positive charge. Due to its molecular structure containing unsaturated cationic groups, it has a powerful adsorption effect on various harmful substances with a negative charge. Similarly, it can also "cleanse" "waste" from the human body, achieving the goals of disease prevention and longevity. Because of this unique function, it is hailed by European and American scientists as the sixth life element of the human body, as important as proteins, fats, sugars, vitamins, and minerals.
The chemical structure of chitin is very similar to that of plant cellulose. Both are polymers of hexose sugars with molecular weights over one million. The basic unit of cellulose is glucose, which is a polymer formed by 300 to 2500 glucose residues linked by β1,4-glycosidic chains. The basic unit of chitin is N-acetylglucosamine, which is a polymer formed by 1000 to 3000 N-acetylglucosamine residues linked by p1,4-glycosidic chains. The basic unit of chitosan is glucosamine. 1. Molecular weight Chitin is a high molecular weight substance, and its molecular weight can reach over one million. The higher the molecular weight, the stronger the adsorption capacity, making it suitable for industrial and environmental applications. Low molecular weight chitosan is easily absorbed by the human body. Chitosan with a molecular weight of about 7000 contains about 30 glucosamine residues. 2. Deacetylation purity Chitin becomes chitosan after deacetylation. Chitin cannot be utilized by the body because it is insoluble in acids, alkalis, and water. After deacetylation, its solubility increases, so it can be absorbed by the body. If more than 55% of the N-acetyl groups are removed, it is called chitosan.
Medical name: Chitosan (polyglucosamine/chitosan).
(1) Can be decomposed and absorbed by enzymes. Chitin is a dietary fiber that is not easily digested and absorbed. If chitin is consumed with vegetables, plant-based foods, milk, and eggs, it can be absorbed. Under the combined action of chitosanase, deacetylase, and lysozyme present in the body, as well as lecithin in milk and eggs, chitin can be decomposed into low molecular weight oligosaccharides and absorbed. Its physiological activity is strongest when decomposed into six molecules of glucosamine. The main absorption site is the large intestine.
(2) Soluble in acidic solutions to form positively charged cationic groups. The chitin molecule contains amino groups (-NH2), which are basic. In the reaction with gastric acid, ammonium salts can be formed, which can shift the pH value in the intestines to the alkaline side, improving an acidic constitution. In this reaction, positively charged cationic groups are formed, which is the only positively charged edible dietary fiber found in nature.
(3) Strong affinity for human cells. When chitin enters the human body and is decomposed into its basic units, it becomes a component of the human body. The basic unit of chitosan is glucosamine, which exists in the human body; the basic unit of chitin is N-acetylglucosamine, which is the basic constituent of hyaluronic acid in the body. Therefore, chitin has a good affinity for human cells and will not cause rejection reactions.
(4) Dissolved chitosan forms a gel state and has strong adsorption capacity. Because the chitin molecule contains polar groups such as hydroxyl and amino groups, it has strong hygroscopicity and can be used as a moisturizer in cosmetics.
(5) Chitin is a natural cellulose (animal dietary fiber) with no toxicity or side effects, and its safety is similar to that of sugar (the lethal dose of sugar is 18g/kg, while that of chitin is 16g/kg).
(6) It can chelate heavy metal ions and serve as an excretory agent for heavy metal ions in the body.
Scope of Application
In industry, it can be used as a mildew-proof, sterilizing, and deodorizing agent for textiles. It can be attached to textile fibers through post-treatment, which is one way to increase the added value of textiles, and is used to manufacture underwear, socks, and home textiles with special functions. In medicine, it can be used for surgical gowns/cloths, wound dressings, burn wound dressings, or further processed into artificial skin for the treatment of large-area burns. Because chitosan is a cationic natural polymer, it has a good inhibitory effect on microorganisms/bacteria/molds and can be used for food preservation, food inner packaging, and is non-toxic and pollution-free. Chitosan can be made into a solution and sprayed on washed or peeled fruits. After the chitosan dries, it forms a colorless, odorless, and breathable film that does not need to be removed before eating. It can also be used in dyes, paper, and water treatment. In agriculture, it can be used as an insecticide and plant antiviral agent. In fisheries, it can be used as fish feed. In cosmetics, it can be used as a beauty agent, hair protector, and moisturizer. In medical supplies, it can be used for contact lenses, artificial skin, sutures, artificial dialysis membranes, and artificial blood vessels.
Special Biological Functions
1. Blood lipid-lowering effect Blood lipids refer to the content of lipids in the blood. Broadly, lipids include neutral fats (glycerol and triglycerides) and lipids (cholesterol, cholesterol esters, and phospholipids). "Chitin" can produce a lipid-lowering effect through several pathways. 1) "Chitin" hinders the digestion and absorption of lipids: Lipids entering the intestinal cavity cannot be absorbed because they are insoluble in water and need to be emulsified by bile acids to turn fat into very small oil droplets, thereby expanding the contact area with pancreatic lipase to facilitate fat digestion. Bile acids (negatively charged) produced by the liver are discharged into the intestinal cavity through the bile duct and easily bind to chitin (positively charged) that accumulates around them, forming a barrier that hinders absorption, while being excreted from the digestive tract. A large amount of bile acids is consumed, thereby hindering the absorption of lipids and achieving the goal of lowering blood lipids.
2) "Chitin" is beneficial for cholesterol conversion: The cholesterol in the human body mainly comes from food intake and its own synthesis. When people mention cholesterol, they often react with fear, believing that cholesterol is the culprit of cardiovascular and cerebrovascular arteriosclerosis diseases, and thus regard cholesterol as a harmful substance to the human body. However, everything has its relativity. In fact, cholesterol is also an indispensable substance for our body. It is an important component of the brain, nerves, sex hormones, cell membranes, etc., and the bile acids, which are indispensable for fat digestion and absorption, are also converted from cholesterol. Therefore, the value of cholesterol should be kept within a normal range. Too little will affect the conversion of bile acids and cause indigestion; once in excess, it will accumulate on the blood vessel walls, worsening blood circulation and causing diseases such as arteriosclerosis. Low-density lipoprotein is the main carrier of cholesterol. Cholesterol is converted into bile acids in the liver, stored in the gallbladder, and discharged into the duodenum to participate in the digestion and absorption of lipids. Afterwards, 95% of the cholesterol is absorbed by the intestinal wall into the blood and returns to the liver, which is the so-called enterohepatic circulation of bile acids. Bile acids in the small intestine combine with chitin and are excreted, greatly reducing the bile acids entering the enterohepatic circulation. The human body transports cholesterol from outside the liver to the liver to produce bile acids, ultimately leading to a decrease in the amount of cholesterol in the body and a reduction in blood lipids.
3) Increase the content of high-density lipoprotein in the blood. Lipids combine with proteins to form lipoproteins. Low-density lipoprotein transports cholesterol from the liver to peripheral tissues, inducing tissue hardening; high-density lipoprotein transports cholesterol from peripheral tissues back to the liver. Chitin lowers blood lipids, causing the cholesterol content in the blood to decrease, the amount of low-density lipoprotein to decrease, and the amount of high-density lipoprotein to increase, which helps prevent the occurrence of arteriosclerosis.
2. Blood pressure-lowering effect 1) Body fluid regulation: There are many causes of hypertension, among which body fluid and endocrine regulation play an important role. Experimental medicine has proven that excessive intake of sodium chloride (salt) by the human body causes chloride ions to accumulate, leading to a state of high blood pressure. The mechanism is that angiotensinogen produced by the liver is normally inactive in the blood. Under the action of converting enzyme (ACE), angiotensin I is generated, which is a physiologically active intermediate product. After a second action of converting enzyme (ACE), angiotensin II, which has extremely strong physiological activity, is generated, acting on the intima of medium and small arteries to increase blood pressure. Chloride ions are activators of converting enzyme (ACE). After an appropriate amount of chitin is dissolved in the body, it forms cationic groups that combine with chloride ions and are excreted, weakening the effect of the converting enzyme, and blood pressure cannot rise.