Views: 13 Author: Site Editor Publish Time: 2022-07-12 Origin: Site
N-acetylneuraminic acid, also known as sialic acid (SA), bird's nest acid, is a naturally occurring amino sugar, which was originally isolated from bovine submandibular adenomucin, hence the name sialic acid. Sialic acid is a nine-carbon monosaccharide derivative containing an amino group, and is a general term for all N- or O-derivatives of neuraminic acid or keto-deoxynonyluronic acid (KDN). Sialic acid usually exists in the form of oligosaccharides, glycolipids or glycoproteins, mainly in the form of short-chain residues at the ends of glycoproteins and glycolipids.
The main sources of sialic acid are breast milk and dairy products. Including human milk, cow milk, goat milk and yogurt, the content of breast milk colostrum is the highest, which can reach more than 1.5 g / liter, and the average content of sialic acid in skim milk powder is 172 mg / 100 g. Another great source of sialic acid is egg foods. In egg white, the content of sialic acid is 0.2~0.3%. Sialic acid is widely distributed in nature and has been found to exist in many organisms. Sialic acid is commonly found in vertebrates and mammals, and it is most abundant in cerebrospinal fluid and mucus. As the degree of biological evolution increases, the content of sialic acid and the types of derivatives in the body also increase. The content of sialic acid in the midbrain of the human body is the highest, and the content of sialic acid in the gray matter of the brain is 15 times that of the liver, lungs and other internal organs.
1. Improve infant memory and intelligence
Sialic acid is an important component of gangliosides in the brain. The content of sialic acid in nerve cell membranes is 20 times that of other cells. Because the transmission of brain information and the conduction of nerve impulses must be achieved through synapses, sialic acid acts on the brain. Brain nutrients for cell membranes and synapses, so sialic acid promotes the development of memory and intelligence. In recent years, further systematic research on sialic acid by scientists has found that the content of sialic acid in human brain cells is 2-4 times that of other animal brain cells, so the intelligence of the human brain is much higher than that of all other animals.
2. Anti-senile dementia
Sialic acid has protective and stabilizing effects on nerve cells. Some neurological diseases, such as early senile dementia and schizophrenia, will reduce the content of sialic acid in the blood or brain of patients. After recovery from drug treatment, the content will return to normal, because sialic acid is involved in neural activity. Gangliosides synthesized from sialic acid have a certain curative effect on the treatment of cerebral ischemia, Parkinson's disease and neurotrauma. Monosialogangliosidase is also effective in the treatment of cerebral ischemia, Parkinson's syndrome, Alzheimer's disease and neurotrauma. Recently, researchers have tried to synthesize some sialic acid derivatives for the treatment of certain neurological diseases.
3. Anti-recognition, improve intestinal absorption of vitamins and minerals
Between molecules and cells, between cells and cells, and between cells and the outside world, sialic acids at the ends of sugar chains can either serve as recognition sites or mask recognition sites. Sialic acid has an extremely strong negative charge, which makes red blood cells and other cells repel each other, avoiding meaningless cell interactions in the blood circulation. Therefore, sialic acid can improve the intestinal absorption of minerals and vitamins, and supplementation of sialic acid can enhance the body's absorption of nutrients.
4. Antibacterial detoxification, antiviral
Due to the special structure of the 9-carbon amino sugar of the sialic acid molecule, there is no enzyme that degrades the substance in the digestive tract system. Therefore, the polypeptide conjugate formed by it will not be degraded by the enzymes in the digestive tract when it passes through the digestive system, and then enter the intestine. In the intestinal tract, specific sialic acid polypeptide conjugates can form competitive binding with pathogenic bacteria, toxins and virus particles entering the intestinal tract, thereby preventing intestinal toxins, pathogenic bacteria and virus particles from binding to intestinal mucosal cells. .
5. Inhibit leukocyte adhesion and reduce inflammation
When tissue is inflamed or lost, white blood cells gather around the inflamed tissue to play an antibacterial and anti-inflammatory effect. In the 1990s, American scientists discovered that the aggregation of leukocytes was related to the process of cell adhesion, and the process of cell adhesion was related to the E-Selection of vascular endothelial cells, a sialic acid-containing tetrasaccharide box on the surface of leukocytes. Therefore, the synthesis of some sialic acid derivatives with simpler structures and more effective than tetrasaccharides as adhesion drugs to treat inflammation will become a research hotspot.
6. Improve human immunity
Sialic acid will not be degraded by enzymes in the digestive tract, and the glycoprotein it forms can block the attachment of pathogens (viruses, bacteria and bacterial toxins) to epithelial cells, improve cell discrimination, detoxify cholera toxins, and prevent pathological colons. Bacterial infection, regulating the half-life of blood proteins, thereby effectively improving the immune function of the human body. At the same time, sialic acid can improve the intestinal absorption of vitamins and minerals, and improve the immunity of infants and mothers.
1. Infant formula
In 2016, the U.S. FDA approved sialic acid for use in infant milk powder and general food for GRAS certification. Many well-known global infant formula manufacturers claim to add sialic acid (N-acetylneuraminic acid) to their formula. In 2003, the Ministry of Health of Malaysia approved the use of sialic acid in the permitted nutrition label. Mead Johnson, Karotani, Meso and Snowmark are marked with sialic acid content on various products of infant formula sold in the Southeast Asian market. But the sialic acid content in most infant formulas is currently derived from whey powder rather than pure sialic acid. It can be expected that when the production cost of sialic acid is reduced to a certain level, sialic acid will gradually replace the whey powder.
2. Food additives and nutritional supplements
Sialic acid sweets are very popular in Japan. Because it is extracted from bird's nest, the price is so high that the candy cannot be priced as a normal lollipop. Sialic acid is used as a nutritional supplement in candy, another important application of sialic acid: anti-influenza virus. Gum with sialic acid can be a good idea to deal with flu season viruses.
Ointments and sprays containing sialic acid have been developed in Japan to maintain healthy hair growth. Due to the antioxidant effects possessed by sialic acid, which has been found in recent studies, it can be reasonably added to cosmetic products such as facial lotions and masks.
4. Pharmaceutical field
In addition to playing an important role in the treatment of nervous system diseases, sialic acid and its derivatives also play an important role in inhibiting sialidase and anti-influenza virus and anti-rotavirus. The main anti-influenza drugs on the market now, such as zanamivir (Elewei), peramivir, oseltamivir (Tamiflu), and the new drug laninamivir, which was launched in Japan in 2010, all belong to neuraminic acid Enzyme inhibitors, which can effectively inhibit the spread of the virus in the body, have therapeutic effects on the new type of influenza.