Name：Sialic acid（SA） N-Acetylneuraminic acid (Neu5Ac)
Molecular Formula：C11H19NO9
Molecular Weight：309.27
CAS No：131-48-6
Sialic acid is a naturally occurring carbohydrate, which was first isolated from cerebral glycolipids and salivary gland mucins. Sialic acid is a large family of 9-carbon monosaccharides and their derivatives, of which N-Acetylneuraminic acid (Neu5Ac) is the most abundant and is also the main active ingredient in cubilose (bird's nest). The content of sialic acid or Neu5Ac is the most important for the grade and price of bird's nest.
In human body, the brain has the highest content of sialic acid. The content of sialic acid in gray matter is 15 times that of internal organs such as liver and lungs.
Sialic acid, participated in a variety of physiological activities in human body, is a well-known nutrient and health food, and has very important applications in brain development, immunity, anti-hypertension, skin whitening, and anti-cancer.
Application
Promotes brain development and cognition
Sialic acid plays a very important role in the production and development of the brain and nervous system. Studies have shown that the addition of Neu5Ac in maternal mice during pregnancy improves the learning and memory functions of their offspring, suggesting the role of sialic acid in neuronal development. Infants and even the entire juvenile brain development stage need to consume enough sialic acid to ensure the normal development of brain function. After childbirth, the level of sialic acid in the mother's body decreases over time. Therefore, consistent intake of adequate sialic acid during pregnancy and lactation can help maintain sialic acid levels in the mother's body. There is also a clear correlation between the content of sialic acid and the content of DHA, both of which are beneficial for early brain development. Sialic acid is also helpful in adults to improve memory.
Immunity enhancing
Sialic acid has the function of antiviral and boosting the body's immunity. Sialic acid is not degraded in the digestive system and can enter the gastrointestinal tract to bind to pathogenic microorganisms, preventing them from adsorbing to intestinal cells. The free sialic acid in the body can not only bind to the influenza virus and prevent it from binding to human cells, but also can achieve antiviral effects by inhibiting the activity of blood cytolglutinin or neuraminidase on the surface of the influenza virus.
Skin whitening
Tyrosinase is a key enzyme involved in melanin synthesis, and Neu5Ac can inhibit tyrosinase activity, thereby reducing the formation of melanin. Studies have shown that the skin whitening effects of Neu5Ac are comparable to several well-known skin whitening agents, such as hydroquinone, arbutin, and kojic acid. Arbutin is not stable enough, it is easy to oxidize, be damaged by light and decompose, and hydroquinone and kojic acid are potentially carcinogenic. The chemical structure of Neu5Ac is different from the above-mentioned whitening agents, with the phenolic ring moiety replaced by a glucose ring. Therefore, it is a safe and effective whitening ingredient.
Anti-hypertensive
Neu5Ac has vasodilatory ability and can promote the stabilization of red blood cells by preventing the aggregation of blood components. Neu5Ac is associated with lipid or cholesterol metabolism, and supplementing with Neu5Ac intake in a high-fat diet can improve lipid metabolism and hyperlipidemia-related coagulation. Therefore, sialic acid can be used as a potential supplement for antihypertensive and hyperlipidemia.
Anticancer
Sialic acid can act as a potent immunomodulator on the surface of cancer cells, providing an immunosuppressive microenvironment and tumor immune evasion. Sialic acid blocking glycomimetics enable a robust tumor immune response, enhance tumor infiltrating natural killer factor-mediated tumor cell killing, and prevent cancer metastasis.
References
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Xu, Y. Shan, N. Wang, Y. Liu, M. Zhang, M. Ma. Sialic acid involves in the interaction between ovomucin and hemagglutinin and influences the antiviral activity of ovomucin International Journal of Biological Macromolecules, 119 (2018), pp. 533-539
Sun, S. Zhang, J. Ren, C.C. Udenigwe. Sialic acid-based strategies for the prevention and treatment of Helicobacter pyloriinfection: Emerging trends in food industry. Critical Reviews in Food Science and Nutrition, 1–12 (2020)
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Z.C.F. Wong, G.K.L. Chan, K.Q.Y. Wub, K.K.M. Poon, Y. Chen, T.T.X. Dong, K.W.K. Tsim. Completed digestion of edible bird’s nest releases free N-acetylneuraminic acid and small peptide: An efficiency method to improve functional properties. Food & Function, 9 (10) (2018), pp. 5139-5149
Zolghadri, A. Bahrami, M.T. Hassan Khan, J. Munoz-Munoz, F. Garcia-Molina, F. Garcia-Canovas, A.A. Saboury. A comprehensive review on tyrosinase inhibitors. Journal of Enzyme Inhibition and Medicinal Chemistry, 34 (1) (2019), pp. 279-309
