Seaweed polysaccharide

Overview of the Applications and Synthesis Methods of Seaweed Polysaccharides Seaweed polysaccharides are natural active polysaccharides from the ocean, mainly derived from a mixture of multiple components of seaweed such as kelp, stagwort (sheep's seaweed), macroalgae, kelp, and fucoidan. According to their sources, they can be divided into four categories: brown algae polysaccharides, red algae polysaccharides, green algae polysaccharides, and blue-green algae polysaccharides. Seaweed polysaccharides are high molecular weight carbohydrates composed of multiple identical or different monosaccharide groups connected by glycosidic bonds. They have high application value, such as agar, carrageenan, and alginate, which have been used in industry for a long time. In addition, it also has various functions such as immune regulation, anti-tumor effect, anti mutation effect, induction of cell differentiation, and antiviral effect. The vast ocean covers 71% of the total area of the Earth and contains extremely abundant biological resources, making it the largest producer of organic matter. Seaweed (Algae or A chemotherapybookeaweeds) is an important component of marine biological resources. In taxonomy, seaweed belongs to the lower order of cryptophytes, mainly divided into four categories - blue-green algae, green algae, red algae, and brown algae, as well as microalgae such as diatoms, dinoflagellates, and dinoflagellates. It is estimated that there are over 15000 species of seaweed growing in the oceans worldwide. Seaweed is the original producer of organic matter and natural enrichment of inorganic matter (including halogens such as chlorine, bromine, iodine, etc.) in the ocean. It is at the bottom of the pyramid in the marine ecosystem - being swallowed by predators. Seaweed also has complex antagonistic and symbiotic relationships with attached and symbiotic microorganisms. Therefore, seaweed can often synthesize secondary metabolites with cytotoxic, antibacterial and other activities to adapt to survival and protect itself. Seaweed contains abundant polysaccharides, accounting for over 50% of its dry weight.

Properties and Structure: Seaweed polysaccharides are a type of seaweed extract, which belongs to lower plants and is mainly divided into four categories: blue-green algae, green algae, red algae, and brown algae. Seaweed bioactive substances can be roughly divided into two types. One is intercellular viscous polysaccharides that are difficult to digest and absorb, mainly including alginate, fucoidan, carrageenan, and other seaweed polysaccharides in brown algae. Another type has a relatively small molecular weight, which can directly or indirectly affect the metabolism of substances in the body after absorption, mainly including terpenoids, seaweed tannins, and gibberellins. Seaweed polysaccharides are a type of multi-component mixture formed by connecting different monosaccharide groups through glycosidic bonds (usually C1,3- and C1,4- bonds). They are a general term for various high molecular weight carbohydrates contained between and within seaweed cells. Generally water-soluble, most of them contain sulfate groups and have high viscosity or solidification ability. There are many types of seaweed polysaccharides, which can be divided into red algae polysaccharides, green algae polysaccharides, brown algae polysaccharides, etc. according to their sources. Among them, brown algae polysaccharides have the most types and quantities. At present, research on the structure of seaweed polysaccharides mainly focuses on the sugar units and content they contain. The polysaccharides in the cell wall of brown algae contain 25% L-fucose, 26% D-xylose, 19% D-ethanolic acid, 13% sulfate, and 12% protein. Extracting fucoidan from brown algae and determining its partial fragment structure composition, the molar ratio of L-fucose, sulfate, and acetate was found to be 1:2.22:0.08. The sugar chain structure is formed by the polymerization of multiple disaccharide units, with a relatively high content of sulfate.

physiological function
Polysaccharides are important components of all living organisms and play a crucial role in controlling cell division, regulating cell growth, and maintaining normal metabolism of living organisms. Seaweed polysaccharides can form negatively charged high molecular weight alginate polymers, which can effectively enrich trace elements and form many bio organic compounds with special physiological functions. They have a stimulating effect on the intestinal mucosa, promote metabolic activities of living organisms, and regulate immune function.

1. Immune regulatory effect
Seaweed polysaccharides can stimulate the differentiation, maturation, and proliferation of various immune active cells (such as macrophages, T lymphocytes, B lymphocytes, etc.), restoring and strengthening the body's immune system.
2. The role of complement system
Excessive activation of complement not only consumes a large amount of complement components, leading to a decrease in the body's ability to resist infections, but also produces a large amount of biologically active substances during the activation process, causing excessive inflammatory reactions and damage to the body's own tissues and cells. And water-soluble polysaccharides from kelp have a certain effect on the complement pathway.
3. Antiviral
Most seaweed polysaccharides contain sulfate groups, and their antiviral effects are positively correlated with the content of SO42-. The antiviral activity of natural sulfated polysaccharides is related to the size of their sulfate groups, their content, and molecular weight. Seaweed polysaccharide calcium complex (CaSP) can selectively inhibit virus replication and transmission in host cells, and the formed calcium ion chelates and sulfate ions are necessary for antiviral effects in host cells. CaSP can also inhibit the replication of a few enveloped viruses, including herpes simplex virus type I, human cytomegalovirus, measles virus, mumps virus, influenza virus and HIV - I.
4. Antioxidant
Excessive reactive oxygen species have a destructive effect on phagocytic cells themselves, as well as other cells, tissues, and biomolecules, while accelerated lipid peroxidation can cause damage and death to normal cells. Seaweed polysaccharides not only have the function of clearing reactive oxygen species, but also significantly reduce the content of lipid peroxides (LPO), increase the activity of peroxidase (CAT) and superoxide dismutase (SOD), and have the effect of clearing excessive free radicals and resisting lipid peroxidation.
5. Anti tumor
Research has shown that seaweed polysaccharides have anti-tumor effects. At present, polysaccharides with anti-tumor effects have been extracted from various organisms such as kelp, seaweed, artemisia, spirulina, brown algae, etc. The inhibitory effect of seaweed polysaccharides on tumors is not directly applied to tumor cells, but achieved by enhancing the biological body's defense ability against tumor cells and strengthening the host's immune system function. The anti-tumor activity of seaweed polysaccharides from different sources and molecular weights also varies.
6. Other biological activities
In addition to the above activities, algal polysaccharides also have biological activities such as hypoglycemic, antihypertensive, anti atherosclerotic, anti-aging and anti radiation.

Preparation method
Water extraction, acid extraction, and alkali extraction: The water extraction conditions are extraction at 80 ℃ for 1 hour and repeated 3 times; The acid extraction conditions were repeated three times with 0.2mol/L HCl at 60 ℃ for 0.5h; The alkaline extraction conditions are 15%, 10%, and 5% NaOH extracted at 60 ℃ for 0.5 hours. During the extraction process, it is necessary to prevent polysaccharide degradation, so the temperature and time of acid-base extraction should be controlled. In order to improve the extraction yield of polysaccharides, it is necessary to apply some new separation and extraction techniques based on the properties of polysaccharides, such as ultrasonic extraction, solvent assisted extraction, aqueous two-phase extraction, microwave extraction combined with enzymatic methods, etc. Alternatively, the separation of polysaccharides from proteins can be achieved through molecular sieves or anion exchange columns. To obtain higher purity polysaccharide products, it is necessary to use methods such as high-performance liquid chromatography, gas chromatography, capillary electrophoresis, etc.

Development Trends
Seaweed polysaccharides are widely used in fields such as medicine, food, feed, and chemical engineering. China has abundant seaweed resources, which urgently need to be recognized and developed by people. Therefore, using cheap seaweed as the material basis and biotechnology as the technological means, producing large quantities of valuable products in industries such as medicine, food, feed, chemical, and cosmetics should become the direction and goal of joint efforts between academia and industry.
The overview, properties and structure, physiological functions, preparation methods, and development trends of seaweed polysaccharides were compiled by Shi Yan editor.