Biological Activities of Polysaccharides

Polysaccharides are polymeric carbohydrate molecules composed of long chain monosaccharide units. The polysaccharide produces constituent monosaccharide or oligosaccharide upon hydrolysis. According to their different sources, polysaccharides can be classified into plant-derived polysaccharides, animal-derived polysaccharides, algae-derived polysaccharides, and microbial-derived polysaccharides. Polysaccharides exert a special biological activity in anti-tumor, anti-inflammatory, anti-viral, anti-aging, anti-coagulation and have broad prospect in the development of new drugs due to their unique functions and low toxicity. This article mainly introduces the biological activities such as anti-viral, anti-aging and anti-tumor activities of polysaccharides.

 

Antiviral Activity

Numerous studies have shown that many polysaccharides have inhibitory effects on some viruses, such as HIV, herpes simplex virus, cytomegalovirus, influenza virus, cystic gastritis virus, Rous sarcoma virus, and sarcoma virus. In recent years, international studies have found that some derivatized polysaccharide preparations such as dextran sulfate have an inhibitory effect on HIV. Because sulfated polysaccharides are a class of polyanionics with negatively charged energy, they can interact with positively charged amino acid residues on the outer membrane glycoprotein of the virus. Moreover, the sulfated polysaccharide has many mimic ligands of cell surface molecules that can directly bind to the cells, thereby preventing the adsorption of the virus. The Germans have developed sulphated xylan as a drug for the treatment of AIDS, and have applied for specialization and put it into clinical trials, which has led to the popular research on sulphated modified polysaccharides at home and abroad. At present, the sulfuric acid values of many sulfated polysaccharides, such as eucalyptus polysaccharide, Prunella vulgaris polysaccharide and Eclipta prostrata polysaccharide, have significant inhibitory effect on HIV-1. Achyranthes polysaccharide sulfate has a strong inhibitory effect on hepatitis B viruses HbsAg and HBeAg, and also has a significant inhibitory effect on herpes simplex virus type 1.

 

Anti-aging Activity

The polysaccharides extracted from the herbs not only promote the body's immune function, but some polysaccharides do have anti-aging effects. For example, Acanthopanax senticosus polysaccharides can extend the average lifespan of fruit flies by 11.7% to 23%. The lycium polysaccharide complex not only has strong immunological activity, but also has significant anti-aging effects. Experiments have shown that the lycium polysaccharide complex can prolong the life span of 5.14% of the silkworm. As a biological effect modifier, plant polysaccharides also have anti-inflammatory, anti-radiation, hypoglycemic effects. With the deepening of research, the plant polysaccharides have broad prospects in the development of new drugs.

 

Anti-tumor Activity

Since the discovery of anti-tumor effects of zymosan in the 1950s, many polysaccharides with anti-tumor activity have been extracted. In terms of the anti-tumor effect of polysaccharides, the polysaccharides can be divided into two categories: one type is cytotoxic polysaccharide, which can directly kill tumor cells, such polysaccharides include achyranthes polysaccharide and acanthopanax senticosus polysaccharide; the second type of polysaccharide acts as a biological immune response regulator, indirectly inhibiting or killing tumor cells by enhancing the body's immune function such as promoting LAK, natural killer (NK) activity, and inducing tumor necrosis production by macrophages. Most polysaccharides with antitumor activity act through this pathway, which is often referred to as host-mediated antitumor activity.

 


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