What are the separation, purification and benefits of active ingredients of Astragalus membranaceus extract polysaccharides?

- Oct 03, 2019-

Astragalus membranaceus extract contains active ingredients such as astragaloside, polysaccharide, protein, and flavonoids. Polysaccharide is one of the main water-soluble components of Astragalus. Astragalus polysaccharide has physiological functions such as anti-oxidation, immune regulation and anti-tumor. Astragalus polysaccharide consists of arabinose, xylose, mannose, rhamnose, galactose and glucose. Because of its outstanding physiological functions, Astragalus polysaccharide has become a research hotspot in medical, food and aquaculture.

1. Extraction of Astragalus Polysaccharide

In the extraction process of Astragalus root extract polysaccharides, it can be degreased first with petroleum ether and ethanol, so that the polysaccharide can be more easily dissolved. Astragalus polysaccharides are extracted by a solvent method, an enzyme-assisted method, a microbial fermentation method, a physical strengthening method, and the like.

1.1 Solvent method

The solvent method is a commonly used extraction method in the industry, and the operation is convenient and the cost is low, but the extraction time is long and the temperature is high, which may cause the active component to be deactivated.

1.2 Enzyme-assisted extraction

The enzyme can destroy the cell wall structure, reduce the resistance of the cell wall and interstitial cells, and increase the extraction rate. The extraction rate of polysaccharides from Astragalus membranaceus was studied by 8 enzymes such as cellulase and pectinase. The effect of glucose oxidase was found to be the best, and the extraction process was optimized by response surface method: enzyme amount 3.0%, treatment time 3.44 d, treatment temperature 56.9. °C, extraction solvent pH 7.8, under this condition, the extraction rate of Astragalus polysaccharides reached 29.96 ± 0.14%, compared with no enzyme assistance increased by 250%. The combination of microwave and cellulase extraction, the extraction rate of polysaccharide reached 16.07%.

1.3 Microbial fermentation extraction

Microbial fermentation extraction is the use of a variety of enzymes produced by microorganisms such as bacteria or fungi to extract substrates. These enzymes can destroy or modify the structure of the cell wall, making the active ingredients in Chinese medicine easier to release, and also degrading the polysaccharide into small molecule polysaccharides and converting them into other types of polysaccharides. The process of fermenting Astragalus polysaccharides by non-S. lactis (FGM) was optimized. The extraction time was 65 min, the extraction temperature was 80 °C, and the ratio of material to liquid was 1:9. The content of fermented Astragalus polysaccharide was 6.72 mg/ml. Fermentation of Astragalus polysaccharide can promote the maturation of mouse bone marrow DC.

1.4 Physical reinforcement method

The physical strengthening methods commonly used in recent years include ultrasonic assisted extraction, microwave assisted extraction, and negative pressure cavitation extraction. The physical strengthening method is to physically destroy the cell structure and let the polysaccharide flow out from the cell, thereby achieving the purpose of increasing the extraction rate. Negative pressure cavitation uses strong cavitation and mechanical vibration to accelerate the entry of active ingredients in plant tissue into the solvent for short-term and low-temperature extraction. That is, it can protect the heat-sensitive substances in plants from being broken, and at the same time reduce macromolecular impurities such as proteins and starches produced by pyrolysis.

2. Purification of Astragalus Polysaccharide

2.1 Deproteinization

It has been reported that the content of protein in the crude polysaccharide of Astragalus membranaceus is greater than 15%. Removal of protein is an important step in obtaining high activity, high value xanthine polysaccharide products. In order to facilitate the operation and increase the yield of polysaccharides, the enzymatic method and the Sevage method are usually used in recent years.

2.2 Astragalus polysaccharide purification

2.2.1 Fractionation precipitation method

Different structures and molecular weights of polysaccharides lead to different polarities, which results in different solubility in organic solvents. According to this principle, the concentration of organic solvents can be sequentially increased to precipitate polysaccharides of different molecular weights. Ethanol is a commonly used precipitant in the fractional precipitation of polysaccharides. Astragalus polysaccharides were fractionated by 30%, 50%, 70%, 75%, 80%, 90% ethanol solution to obtain 6 different components. The structure, composition and oxidation resistance of each component were analyzed. The results showed that the molecular weight of the obtained polysaccharide decreased gradually with the increase of ethanol concentration, and the content of galactose, mannose and rhamnose in the polysaccharide increased sequentially. The content of glucose decreases in turn, but the antioxidant activity is enhanced, and the antioxidant activity is related to the structure of the polysaccharide.

2.2.2 Column chromatography

The most widely used in the separation and purification of Astragalus polysaccharides is ion exchange column chromatography and gel column chromatography. Ion exchange column chromatography is mainly used for crude separation of single-component polysaccharides in crude polysaccharide extracts. Separation or further purification of the polysaccharide can be achieved by using gel column chromatography of different specifications depending on the structure and molecular weight of the isolated polysaccharide.

2.2.3 Membrane separation

The membrane separation process carried out at normal temperature has the advantages of not using an organic solvent, high separation selectivity, and easy use in combination with other methods. Ultrafiltration is a membrane separation technology that emerged in the 1960s. Because of its high yield and minimal damage to the product, it is widely used for the separation and purification of plants. The over-frequency vibration membrane filtration technology and the ethanol fractionation precipitation method were applied to the purification of Astragalus polysaccharides, and it was found that the former was easy to obtain a polysaccharide having a relatively uniform molecular weight. At present, the separation and purification methods of Astragalus polysaccharides are relatively fixed, and the separation and purification processes of other polysaccharides can be referred to in order to better purify the polysaccharides of Astragalus membranaceus, for example, separation and purification of polysaccharides by membrane integration technology: separation and purification of polysaccharides by microfiltration and ultrafiltration , two components can be obtained. In addition to the commonly used membrane separation methods, there are microfiltration, nanofiltration, etc., which are rarely used in the purification of Astragalus polysaccharides, but have been used for the purification of other plant polysaccharides, and can be used for the separation and purification of Astragalus polysaccharides.

3. Benefits and Application

3.1 Medical

Because Astragalus polysaccharide has good pharmacological effects such as immune regulation, anti-tumor and anti-inflammatory. At present, Astragalus polysaccharide has made great progress in the treatment of diseases. It has been used clinically to treat diseases such as cancer, asthma, and diabetes. The treatment of other diseases remains at the animal testing stage.

3.1.1 Tumor

At present, the main method for treating cancer is chemotherapy, but chemotherapy is often accompanied by some side effects and may also produce drug resistance. Astragalus polysaccharide can reduce the toxic side effects of drugs while enhancing immunity, inhibiting tumor growth and promoting apoptosis. In recent years, Astragalus polysaccharides have developed rapidly in the treatment of cancer. Studies have shown that Astragalus polysaccharide can inhibit gastric cancer MGC-803 cells, human non-small cell lung cancer A549 cells and human liver cancer HepG2 cells, and induce apoptosis of gastric cancer MGC-803 cells. In addition, Astragalus polysaccharide can also be combined with gemcitabine to treat pancreatic cancer, and adriamycin liposome for the treatment of liver cancer.

3.1.2 Asthma

Astragalus polysaccharide may enhance the anti-inflammatory activity by regulating immune cell function and cytokine expression, thus playing a good role in respiratory diseases. On the basis of conventional treatment, injection of astragalus polysaccharide injection into asthma patients can significantly reduce the level of inflammatory cells contained in BALF or sputum, maintain immune balance, improve immunity, restore lung function, and reduce the risk of adverse reactions. Other studies have shown that Astragalus polysaccharide can improve the immune stress of patients through immune regulation of T lymphocytes, improve the immune system of patients, and thus improve the cure rate of patients with bronchial asthma.

3.1.3 Diabetes

Astragalus polysaccharide can improve the renal function of patients by regulating the immune function of patients and reducing the inflammatory response. Studies have shown that the combination of Astragalus polysaccharide and Sanhuang Huayu Decoction can reduce the plasma inflammatory factor plasma plasminogen activator inhibitor-1 in patients with early diabetic nephropathy.

3.1.4 Other

In addition, Astragalus polysaccharides can also be used to treat cardiovascular and neurological diseases. Studies have shown that Astragalus polysaccharide has a good protective effect on cardiomyocyte hypertrophy and inflammatory response induced by AngII.

3.2 Food

The booklet on Health Food Raw Materials states that Astragalus polysaccharides can be used as a raw material for health foods.

3.3 Breeding

3.3.1 Immunopotentiator

Astragalus polysaccharide can improve the serum environment, stimulate the body's immune response, promote the secretion of cytokines, and enhance the antibody level in the body to enhance the vaccine effect. Real-time quantitative RT-PCR analysis showed that in the spleen and head kidney tissues, the mRNA expression of the inflammatory cytokine IL-1β increased in the early stage of immunization, triggering the Th1 immune response, and the cytokines IL-2 and IFN-γ2 were increased in the whole immune phase. High, serum IgM is significantly enhanced, Astragalus polysaccharide can enhance the efficacy of A. sinensis vaccine.

As a natural feed additive, Astragalus polysaccharide can not only improve the body's immunity but also improve the body's production performance. When the amount of Astragalus polysaccharide added to the feed is 50-400 mg/kg, it can significantly enhance the non-specific immunity and antioxidant capacity of the loach.

3.3.2 Reproduction

Artificial insemination is widely used in modern pig farms. Liquid nitrogen preservation semen has a short life span, and cryopreservation can prolong the life of semen. In the process of freezing and thawing of semen, how to establish a strong antioxidant system for sperm has become an urgent problem to be solved. Astragalus polysaccharide has good antioxidant function, so Astragalus polysaccharide may be a good choice to solve this problem. Studies have confirmed that Astragalus polysaccharide can inhibit the dephosphorylation of sperm proteins by affecting the pathway of reactive oxygen species into the cyclic adenosine phosphate. Studies have shown that Astragalus polysaccharide can improve the in vitro fertilization efficiency and embryo development ability by reducing the content of active oxygen in pig thawed semen and improving the antioxidant capacity of sperm.

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