What’s Astragalus Polysaccharides?

Distilled Water Extraction

Astragalus polysaccharides is dissolved in water and insoluble in ethanol macromolecular compounds, most of the manufacturers: extracted with the use of distilled water process is place in distilled water to boil after crushing astragalus root astragalus polysaccharide dissolved in water, change its pH is neutral, after the merger filtrate concentrated ethanol precipitation separation of polysaccharide from extract, acetone, washing coarse polysaccharide resulting from the frozen and vacuum drying. This extraction method is simple and easy to operate, but it can extract flavonoids, saponins and other chemicals in the astragalus at the same time. These substances are easy to be oxidized and discolored in the air, affecting the purity and color of the product. The extraction cost is high and the output efficiency is about 2.5%.

Alkaline Extraction

As a component of astragalus membranaceus fiber, the extraction efficiency depends on the swelling and solubility of astragalus membranaceus fiber. The swelling and solubility of the fibers in alkali were significantly increased compared with that in water, and the ester bonds between the fibers were easily broken under alkaline conditions, leading to peeling reaction and more polysaccharides could be extracted. Therefore, astragalus polysaccharides are mostly extracted from water and weak base solutions at different temperatures. Generally, CaO or Na2CO3 aqueous solution with pH 9~10 is boiled for extraction, and the concentration time is about pH 6.5. Ethanol with a certain concentration is added for centrifugation. After water dissolution and filtration, ethanol precipitation, acetone washing, freezing or vacuum drying are used to obtain crude polysaccharides.

The results showed that astragalus polysaccharides were extracted by alkali-ethanol precipitation and alkali-ethanol extraction precipitation. The crude astragalus polysaccharides were purified by different flocculants. The polysaccharide content was determined by the phenol-concentrated sulfuric acid method. ZTC1+1 natural clarifier ⅱ could remove impurities in APS extract and improve the purity of APS. Since alkalinity may affect the spatial structure of polysaccharides, further study is needed.

Microwave Extraction

Microwave refers to electromagnetic waves with a frequency of 300MHz to 300GHz, that is, electromagnetic waves with a wavelength between 1 meter and 1 millimeter. Microwave has strong penetration, high selectivity, and high heating efficiency, microwave radiation can greatly accelerate the reaction speed, reaction time in minutes, or seconds. When microwave technology is applied to a plant cell wall, its thermal effect can break the cell wall and inactivate enzymes in the cell membrane, and polysaccharide can be extracted easily through cell wall and cell membrane barrier, which can effectively improve the extraction rate of polysaccharide. Microwave has a good auxiliary effect on the extraction of APS, can reduce the amount of extraction agent, shorten the extraction time and improve the yield of polysaccharides, in many aspects better than the traditional direct heating method.

Chinese scholars used the extraction rate of astragalus polysaccharides as the index to study the ultrasonic-assisted extraction process of astragalus polysaccharides by orthogonal test. The optimized conditions were determined as follows: solid-liquid ratio of 30∶1, the ultrasonic intensity of 120W and extraction time of 1h, and the optimal extraction rate of astragalus polysaccharides reached 92.1%.

Ultrasonic Extraction

Sound waves with frequencies higher than 20,000 Hertz are called “ultrasonics”. Ultrasonic has strong directivity, energy concentration and penetrating ability, which can spread in a variety of different media and can spread far enough distance. The mechanical crushing and cavitation of ultrasonic wave can easily disperse and destroy the plant tissue, accelerate the penetration of solvent through the tissue, improve the extraction rate of herbal active ingredients, and have the advantages of saving solvent, shortening extraction time and reducing energy consumption. However, side reaction is not easy to control and reaction equipment is expensive.

The results showed that astragalus root powder was used as a material to extract Astragalus polysaccharides by ultrasonic method, and the optimal extraction conditions were predicted as follows: extraction time 90 min, power 250 W, temperature 80℃.

Enzyme Extraction

Enzymes are proteins, RNA, or complexes that catalyze a specific chemical reaction. They are biocatalysts that speed up a reaction by reducing the activation energy of the reaction without changing the equilibrium point of the reaction. The commonly used enzyme preparations include cellulase, hemicellulase, pectinase and amylase, especially the application of cellulase through enzymatic hydrolysis reaction, can be relatively mild decomposition of plant tissues, destroy the dense structure of cell wall, accelerate the release and dissolution of medicinal active ingredients, improve the extraction rate of medicinally active ingredients.

Many astragalus polysaccharides manufacturers in China have used ultrasound combined with enzyme to effectively extract TOTAL APS. The results showed that the factors affecting the extraction rate of TOTAL APS were listed in the following order: ultrasonic extraction time, ultrasonic extraction temperature, enzyme content, solid-liquid ratio, The optimal extraction parameters were as follows: ultrasonic extraction time 30 min, ultrasonic extraction temperature 40℃, solid-liquid ratio 1∶20(g∶mL), enzyme content 10 mg.