Extraction method of high-purity astragalus polysaccharide

Abstract

The invention relates to a method for extracting high-purity astragalus polysaccharide. The method comprises the following specific steps: washing astragalus, drying and crushing into coarse powder; under a certain solid-liquid ratio, extracting astragalus polysaccharide by using ultrasonic waves; carrying out mixed enzymolysis on the extracting solution and cellulase, and terminating enzyme reaction through heating; and mixing the enzymatic hydrolysate with specific molecularly imprinted polymers (MIPs), specifically adsorbing the astragalus polysaccharide through a molecular recognition effect, and eluting and purifying by using a mixed solution of water and ethanol. In the preparation process of the MIPs, oligosaccharide fragments of astragalus polysaccharide, acrylamide, ethylene glycol dimethacrylate, potassium persulfate and lauryl sodium sulfate are dissolved in methanol, and free radical polymerization reaction is carried out under the protection of nitrogen. Experimental results show that the purity and the extraction rate of the astragalus polysaccharide extracted by the method are remarkably improved, and the method has the advantages of simplicity and convenience in operation, high efficiency, economy, environmental protection and the like.

Description

Technical Field

[0001] The invention relates to the technical field of astragalus polysaccharides, and in particular to a method for extracting high-purity astragalus polysaccharides. Background Art

[0002] As a natural product with a wide range of pharmacological effects, astragalus polysaccharide has been widely used in the field of traditional Chinese medicine and health products. With the in-depth research on its immunomodulatory, antioxidant, anti-inflammatory and other effects, the market demand for high-purity astragalus polysaccharide continues to increase. At present, the extraction methods of astragalus polysaccharide mainly include traditional water extraction, alcohol precipitation, ultrasound-assisted extraction and microwave-assisted extraction. Chinese patent CN104311689A discloses a method for extracting astragalus polysaccharide, comprising the following steps: selecting sun-dried astragalus, crushing and passing through a 40-80 mesh sieve to obtain astragalus powder, adding water to the astragalus powder and stirring evenly, the weight ratio of astragalus powder to water is 1:5-10, soaking in water for 8-16 hours, adding cellulase for enzymolysis, then adding alkaline protease and bromelain, enzymolysis under microwave conditions, concentrating and decolorizing after enzymolysis, centrifuging, taking the supernatant and concentrating it for alcohol precipitation, centrifuging again, washing the precipitate with ethanol, freeze-drying and crushing to obtain astragalus polysaccharide; Chinese patent CN104311689A discloses a process for microwave-assisted extraction of astragaloside and astragalus polysaccharide, which comprises the following steps: a, weighing astragalus medicinal materials; b, placing the medicinal materials in a microwave extraction device, with a microwave power of 500W-900W and a temperature of 70°C, extracting for a total of 3 times, adding 50%-90% ethanol for the first time , extract for 10min-30min; add 50%-90% ethanol for the second time and extract for 10min-30min; add distilled water for the third time and extract for 20min-40min; c. concentrate the ethanol extracts of the first and second times, remove the ethanol, add the water extract of the third time, mix and concentrate to obtain the astragaloside and astragalus polysaccharide extracts of the present invention; Chinese patent CN109517084A discloses an extraction and purification process of astragalus polysaccharide, which specifically includes the following steps: (1) crushing; (2) water extraction; (3) defatting; (4) primary alcohol precipitation; (5) secondary alcohol precipitation; (6) ultrasonic extraction; (7) enzyme treatment; (8) enzyme inactivation and filtration; (9) separation; (10) primary concentration; (11) secondary concentration; (12) drying; These methods can extract astragalus polysaccharide to a certain extent, but have the problems of low extraction efficiency, low purity, complicated steps and high energy consumption. In addition, these traditional methods are prone to introduce impurities, which affect the purity and biological activity of the extracts and cannot meet high-standard application requirements. Therefore, it is urgent to develop an efficient, high-purity, and easy-to-operate method for extracting astragalus polysaccharides to meet the requirements of modern industry and medicine.

[0003] In order to overcome the shortcomings of the existing technology, we proposed a method for extracting astragalus polysaccharides based on specific molecular imprinting polymers (MIPs). Molecular imprinting technology is an emerging molecular recognition technology that introduces specific template molecules into a polymer matrix to form recognition sites that are complementary to the target molecule structure, thereby achieving highly selective recognition and separation of the target molecule. In the extraction process of astragalus polysaccharides, the use of MIPs can significantly improve the selectivity and specificity of the extraction process, thereby improving the purity of the polysaccharide. In addition, this method can reduce the introduction of impurities and protect the biological activity of polysaccharides, thereby improving the quality and application value of the extract.

[0004] In summary, the astragalus polysaccharide extraction method based on specific molecular imprinting polymers not only effectively overcomes the limitations of traditional extraction methods and provides an efficient, economical and environmentally friendly solution, but also greatly improves the extraction purity and biological activity of astragalus polysaccharides by optimizing the molecular recognition and extraction process, opening up new paths for research and industrial applications in related fields. Summary of the invention

[0005] Existing technologies can extract astragalus polysaccharides to a certain extent, but there are problems such as low extraction efficiency, low purity, complicated steps, and high energy consumption. In addition, these traditional methods are prone to introduce impurities, which affects the purity and biological activity of the extracts and cannot meet high-standard application requirements.

[0006] The present application provides a method for extracting high-purity astragalus polysaccharides, comprising the following steps:

[0007] Step 1, wash the astragalus, remove the dust and impurities on the surface, and then dry it in an oven at 50-60° C. to constant weight, and grind the dried astragalus into coarse powder using a grinder; wherein the coarse powder has a mesh size of 40-60;

[0008] Step 2, adding the screened astragalus powder to distilled water according to a certain solid-liquid ratio, and extracting in an ultrasonic extraction device;

[0009] Step 3, adding the extract obtained in step 2 and cellulase into an enzymatic reaction vessel, and performing enzymatic reaction for 3 hours. After the enzymatic reaction is completed, heating to 95° C. and maintaining for 10 minutes to terminate the enzymatic reaction;

[0010] Step 4, mixing the enzymatic hydrolyzate with the specific molecular imprinting polymer, stirring for 1 hour to allow the astragalus polysaccharide to be specifically adsorbed on the specific molecular imprinting polymer, using a mixed solution of water and ethanol to elute the astragalus polysaccharide adsorbed on the specific molecular imprinting polymer, and collecting and concentrating the eluate; wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:1.

[0011] By adopting the above technical scheme, first of all, the cleaning, drying and crushing of Astragalus are the initial steps of the entire extraction process. By washing with water, dust, soil and other impurities on the surface of Astragalus can be removed, ensuring that no additional pollutants are introduced during the extraction process and ensuring the purity of the extract. Drying to constant weight in an oven at 50-60°C and evaporating the moisture in Astragalus by heating can prevent microbial growth and enzyme autolysis, while improving the storage stability of Astragalus after crushing. The dried Astragalus is crushed into 40-60 mesh coarse powder by a grinder, which increases the specific surface area, is conducive to the penetration of solvents and the dissolution of effective ingredients in the subsequent extraction process, thereby improving the extraction efficiency.

[0012] Next is the ultrasonic extraction stage. Astragalus powder is added to distilled water at a certain material-liquid ratio (solid-liquid ratio) to ensure that there is sufficient solvent to fully penetrate and dissolve the effective ingredients in Astragalus, and to avoid low extraction efficiency caused by insufficient solvent. Ultrasonic extraction forms tiny bubbles in the liquid through the cavitation effect. These bubbles grow and burst rapidly, generating local high temperature and high pressure, which enhances the destructive power of the solvent on cell walls and cell membranes. In this way, ultrasonic extraction can effectively destroy cell walls and cell membranes, promote the release of Astragalus polysaccharides, and improve extraction efficiency and extraction rate.

[0013] In the enzymatic hydrolysis step, cellulase plays a key role. Cellulase can hydrolyze cellulose, breaking it down into soluble oligosaccharides and glucose, and releasing astragalus polysaccharides wrapped in the cell wall. The use of cellulase improves the extraction purity and efficiency of astragalus polysaccharides. The enzymatic hydrolysis reaction is carried out under suitable temperature (45°C) and pH (5.0) conditions. Cellulase has the highest activity under these conditions and can fully hydrolyze the cellulose in astragalus. After the enzymatic hydrolysis reaction is carried out for 3 hours, it is heated to 95°C and maintained for 10 minutes to destroy the structure of the enzyme, inactivate it, terminate the enzymatic hydrolysis reaction, prevent excessive hydrolysis, and ensure the integrity and quality of astragalus polysaccharides.

[0014] Finally, during the adsorption and elution process of specific molecular imprinted polymers (MIPs), the enzymatic hydrolysate was mixed with MIPs to selectively adsorb APS through molecular recognition. The imprinting sites on MIPs matched the specific structure of APS, and the APS was specifically adsorbed on MIPs after stirring for 1 hour, thereby improving the purity of APS in the extract. A mixed solution of water and ethanol (volume ratio 1:1) was used to elute the APS adsorbed on MIPs. The water and ethanol in the mixed solution can destroy the weak interactions (such as hydrogen bonds and hydrophobic interactions) between APS and the imprinting sites, and effectively elute APS. After collecting the eluate, the solvent was removed by rotary evaporation or freeze drying to obtain high-purity APS.

[0015] In summary, this technical solution improves the dissolution and purity of astragalus polysaccharides by combining ultrasonic extraction and enzymatic hydrolysis; and uses the molecular recognition technology of specific molecular imprinting polymers to achieve selective adsorption and purification of astragalus polysaccharides. The entire process effectively improves the extraction efficiency and purity of astragalus polysaccharides, and ultimately obtains a high-purity astragalus polysaccharide product.

[0016] As a preferred technical solution for a method for extracting high-purity astragalus polysaccharide, the preparation steps of the specific molecular imprinted polymer include the following: dissolving a template molecule, a functional monomer, a cross-linking agent, an initiator and a surfactant in an appropriate amount of methanol, performing a free radical polymerization reaction under nitrogen protection, and after the polymerization reaction, eluting the polymer with a mixed solution of ethanol and water to remove the template molecule and obtain the specific molecular imprinted polymer; wherein the reaction temperature is controlled at 60°C, the reaction time is 12 hours, and the volume ratio of water to ethanol in the mixed solution of water and ethanol is 7:3.

[0017] By adopting the above technical scheme, this technical scheme reasonably selects template molecules, functional monomers, crosslinking agents, initiators and surfactants, and performs free radical polymerization under appropriate reaction conditions, and then uses a mixed solution of water and ethanol to elute and remove the template molecules, thereby preparing specific molecular imprinted polymers with high selectivity and high adsorption capacity. This process fully utilizes the mechanism of free radical polymerization and surfactants, ensures the structural and functional characteristics of the polymer, and thus improves the performance and efficiency of MIPs in practical applications.

[0018] As a preferred technical solution for the extraction of high-purity astragalus polysaccharide, the template molecule is an oligosaccharide fragment of astragalus polysaccharide, the functional monomer is acrylamide, the cross-linking agent is ethylene glycol dimethacrylate, and the initiator is potassium persulfate.

[0019] By adopting the above technical scheme, in the preparation process of specific molecular imprinted polymers (MIPs), oligosaccharide fragments of astragalus polysaccharides are used as template molecules, acrylamide (AAm) as functional monomers, ethylene glycol dimethacrylate (EGDMA) as crosslinking agent, potassium persulfate (K2S2O8) as initiator, and a three-dimensional crosslinked network structure is formed through free radical polymerization reaction. Astragalus polysaccharide oligosaccharide fragments have many advantages as molecular templates in the preparation of specific molecular imprinted polymers (MIPs). First, the oligosaccharide fragments have specific structural characteristics and can form imprinting sites that are highly matched with astragalus polysaccharides, thereby improving the selective recognition and specific adsorption capacity of MIPs. Secondly, the oligosaccharide fragments are easier to dissolve and handle, simplifying the polymerization process and improving the controllability and repeatability of the preparation process. In addition, the oligosaccharide fragments can form stable imprinting complexes during the polymerization process to ensure the stability and reproducibility of the imprinting sites. Its small molecular structure helps to evenly distribute, increase the number and quality of imprinting sites, and improve the adsorption capacity and efficiency of MIPs. At the same time, the specific structure of the oligosaccharide fragments reduced nonspecific adsorption and enhanced the extraction effect of APS.

[0020] As a preferred technical solution for the extraction of high-purity astragalus polysaccharide, the mass ratio of the template molecule, the functional monomer, the cross-linking agent and the initiator is (0.1 to 0.5):(0.2 to 1):(1.0 to 5.0):(0.005 to 0.2).

[0021] By adopting the above technical solution, the mass ratio between the various substances is optimized, and the performance and efficiency of MIPs in practical applications are improved.

[0022] As a preferred technical solution for the extraction of high-purity astragalus polysaccharides, in step 2, the solid-liquid ratio (w / v) is 1:10 to 1:15, the ultrasonic power is set to 200 to 400 W, the extraction temperature is 30 to 50° C., and the extraction time is 30 to 60 min.

[0023] By adopting the above technical scheme, optimizing the solid-liquid ratio, ultrasonic power, extraction temperature and extraction time, the extraction efficiency and purity of astragalus polysaccharides can be significantly improved. Specifically, the appropriate solid-liquid ratio ensures the sufficiency of the solvent and the extraction efficiency; the ultrasonic power enhances cell disruption and astragalus polysaccharide release through the cavitation effect; the appropriate extraction temperature improves the permeability of the solvent and the solubility of astragalus polysaccharides; and the optimized extraction time ensures sufficient extraction while avoiding the degradation of polysaccharides. These optimization steps combined provide an efficient and economical astragalus polysaccharide extraction process, which can significantly improve the extraction efficiency and product quality.

[0024] As a preferred technical solution for extracting high-purity astragalus polysaccharides, in step 3, the amount of cellulase used is 2 to 5 wt % of the weight of the astragalus powder, the pH value is adjusted to 5.0, and the temperature is controlled at 40 to 50°C.

[0025] By adopting the above technical scheme, the activity and stability of the enzyme are optimized. Cellulase binds to cellulose at a suitable pH value and temperature, catalyzing the hydrolysis of β-1,4-glycosidic bonds, decomposing cellulose into oligosaccharides and glucose, thereby releasing astragalus polysaccharides. The enzymatic hydrolysis reaction is carried out in a constant temperature water bath of 40 to 50°C for 3 hours, and then heated to 95°C to terminate the enzyme reaction, ensuring that cellulose is efficiently hydrolyzed, maximizing the extraction efficiency and purity of astragalus polysaccharides.

[0026] As a preferred technical solution for the extraction method of high-purity astragalus polysaccharide, the surfactant is sodium dodecyl sulfate, and the surfactant accounts for 1% to 10% of the mass of the functional monomer.

[0027] By adopting the above technical scheme, sodium dodecyl sulfate (SDS) is used as a surfactant to enhance the interaction between template molecules and functional monomers by reducing surface tension and forming micellar structures when preparing specific molecular imprinted polymers (MIPs). Specifically, the hydrophobic tail of SDS interacts with the oligosaccharide fragments and acrylamide of astragalus polysaccharides to ensure the stability of these molecules in the reaction environment. The presence of SDS promotes the nucleation and growth of the polymer, and leaves pores in the polymer matrix, increasing the specific surface area and adsorption capacity. After the polymerization reaction is completed, SDS is washed off, leaving evenly distributed imprinting sites, thereby improving the selectivity and adsorption performance of MIPs. In this way, SDS effectively promotes the formation and distribution of imprinting sites, ensuring the high selectivity and high adsorption capacity of MIPs for astragalus polysaccharides.

[0028] The high-purity astragalus polysaccharide extraction method provided by the present invention improves the dissolution and purity of astragalus polysaccharides by combining ultrasonic extraction and cellulase enzymatic hydrolysis treatment; and utilizes the molecular recognition technology of specific molecular imprinting polymers (MIPs) to achieve selective adsorption and purification of astragalus polysaccharides. The experimental results show that the extraction rate and purity of astragalus polysaccharides extracted by this method are significantly higher than those of the traditional method and the MIPs extraction method under unoptimized conditions. Specifically, the extraction rate of astragalus polysaccharides extracted in the embodiment is between 20.5% and 28.4%, and the purity is between 94.2% and 99.2%, which are significantly higher than those of the comparative example, proving that this method has high extraction efficiency and purity. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0032] Preparation Example 1

[0033] Oligosaccharide fragments of astragalus polysaccharide, acrylamide, ethylene glycol dimethacrylate, potassium persulfate and sodium dodecyl sulfate are dissolved in an appropriate amount of methanol, wherein the amount of methanol is twice the mass of the above substances, and a free radical polymerization reaction is carried out under nitrogen protection. After the polymerization reaction, the polymer is eluted with a mixed solution of ethanol and water to remove the template molecule, thereby obtaining a specific molecular imprinting polymer; wherein the reaction temperature is controlled at 60°C, the reaction time is 12 hours, the volume ratio of water to ethanol in the mixed solution of water and ethanol is 7:3, the mass ratio of oligosaccharide fragments of astragalus polysaccharide, acrylamide, ethylene glycol dimethacrylate, potassium persulfate and sodium dodecyl sulfate is 0.1:0.2:1.0:0.005, and the sodium dodecyl sulfate accounts for 1wt% of the mass of acrylamide.

[0034] The difference between Preparation Examples 2 to 5 and Preparation 1 is that the mass ratios of the oligosaccharide fragments of astragalus polysaccharide, acrylamide, ethylene glycol dimethacrylate and potassium persulfate are different.

[0035] The oligosaccharide fragments of Astragalus polysaccharides, acrylamide, ethylene glycol dimethacrylate and potassium persulfate of Preparation Examples 1 to 5 are shown in Table 1.

[0036] Table 1

[0037]

[0038]

[0039] The difference between Preparation Examples 6 to 10 and Preparation Example 1 is that the added amount of sodium dodecyl sulfate is different.

[0040] The addition amount of sodium dodecyl sulfate in Preparation Example 1 and Preparation Examples 6 to 5 is shown in Table 2.

[0041] Table 2

[0042]

[0043] Example 1

[0044] Step 1, wash the astragalus, remove the dust and impurities on the surface, and then dry it in an oven at 50°C to constant weight, and grind the dried astragalus into coarse powder using a grinder; wherein the coarse powder is 60 mesh;

[0045] Step 2, adding the screened astragalus powder to distilled water according to a certain solid-liquid ratio, and extracting in an ultrasonic extraction device; wherein the solid-liquid ratio (w / v) is 1:10, the ultrasonic power is set to 200 W, the extraction temperature is 50° C., and the extraction time is 40 min;

[0046] Step 3, adding the extract obtained in step 2 and cellulase into an enzymatic reaction vessel, performing enzymatic reaction for 3 hours, and after the enzymatic reaction is completed, heating to 95° C. and maintaining for 10 minutes to terminate the enzymatic reaction; wherein the amount of cellulase used is 2wt% of the weight of the astragalus powder, the pH value is adjusted to 5.0, and the temperature is controlled at 40° C.;

[0047] Step 4, mixing the enzymatic hydrolyzate with the specific molecular imprinting polymer of Preparation Example 1, stirring for 1 hour to allow the astragalus polysaccharide to be specifically adsorbed on the specific molecular imprinting polymer, using a mixed solution of water and ethanol to elute the astragalus polysaccharide adsorbed on the specific molecular imprinting polymer, and collecting and concentrating the eluate; wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:1.

[0048] Example 2

[0049] Step 1, wash the astragalus, remove the dust and impurities on the surface, and then dry it in an oven at 60°C to constant weight, and grind the dried astragalus into coarse powder using a grinder; wherein the coarse powder is 40 mesh;

[0050] Step 2, adding the screened astragalus powder to distilled water according to a certain solid-liquid ratio, and extracting in an ultrasonic extraction device; wherein the solid-liquid ratio (w / v) is 1:15, the ultrasonic power is set to 400 W, the extraction temperature is 30° C., and the extraction time is 60 min;

[0051] Step 3, adding the extract obtained in step 2 and cellulase into an enzymatic reaction vessel, performing enzymatic reaction for 3 hours, and after the enzymatic reaction is completed, heating to 95° C. and maintaining for 10 minutes to terminate the enzymatic reaction; wherein the amount of cellulase used is 5wt% of the weight of the astragalus powder, the pH value is adjusted to 5.0, and the temperature is controlled at 50° C.;

[0052] Step 4, mixing the enzymatic hydrolyzate with the specific molecular imprinting polymer of Preparation Example 2, stirring for 1 hour to allow the astragalus polysaccharide to be specifically adsorbed on the specific molecular imprinting polymer, using a mixed solution of water and ethanol to elute the astragalus polysaccharide adsorbed on the specific molecular imprinting polymer, and collecting and concentrating the eluate; wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:1.

[0053] Example 3

[0054] Step 1, wash the astragalus, remove the dust and impurities on the surface, and then dry it in an oven at 55°C to constant weight, and grind the dried astragalus into coarse powder using a grinder; wherein the coarse powder is 50 mesh;

[0055] Step 2, adding the screened astragalus powder to distilled water according to a certain solid-liquid ratio, and extracting in an ultrasonic extraction device; wherein the solid-liquid ratio (w / v) is 1:12, the ultrasonic power is set to 300 W, the extraction temperature is 40° C., and the extraction time is 50 min;

[0056] Step 3, adding the extract obtained in step 2 and cellulase into an enzymatic reaction vessel, performing enzymatic reaction for 3 hours, and after the enzymatic reaction is completed, heating to 95° C. and maintaining for 10 minutes to terminate the enzymatic reaction; wherein the amount of cellulase used is 3wt% of the weight of the astragalus powder, the pH value is adjusted to 5.0, and the temperature is controlled at 40° C.;

[0057] Step 4, mixing the enzymatic hydrolyzate with the specific molecular imprinting polymer of Preparation Example 3, stirring for 1 hour to allow the astragalus polysaccharide to be specifically adsorbed on the specific molecular imprinting polymer, using a mixed solution of water and ethanol to elute the astragalus polysaccharide adsorbed on the specific molecular imprinting polymer, and collecting and concentrating the eluate; wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:1.

[0058] Example 4

[0059] Step 1, wash the astragalus, remove the dust and impurities on the surface, and then dry it in an oven at 55°C to constant weight, and grind the dried astragalus into coarse powder using a grinder; wherein the coarse powder is 50 mesh;

[0060] Step 2, adding the screened astragalus powder to distilled water according to a certain solid-liquid ratio, and extracting in an ultrasonic extraction device; wherein the solid-liquid ratio (w / v) is 1:12, the ultrasonic power is set to 200 W, the extraction temperature is 40° C., and the extraction time is 50 min;

[0061] Step 3, adding the extract obtained in step 2 and cellulase into an enzymatic reaction vessel, performing enzymatic reaction for 3 hours, and after the enzymatic reaction is completed, heating to 95° C. and maintaining for 10 minutes to terminate the enzymatic reaction; wherein the amount of cellulase used is 3wt% of the weight of the astragalus powder, the pH value is adjusted to 5.0, and the temperature is controlled at 50° C.;

[0062] Step 4, mixing the enzymatic hydrolyzate with the specific molecular imprinting polymer of Preparation Example 4, stirring for 1 hour to allow the astragalus polysaccharide to be specifically adsorbed on the specific molecular imprinting polymer, using a mixed solution of water and ethanol to elute the astragalus polysaccharide adsorbed on the specific molecular imprinting polymer, and collecting and concentrating the eluate; wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:1.

[0063] Example 5

[0064] Step 1, wash the astragalus, remove the dust and impurities on the surface, and then dry it in an oven at 55°C to constant weight, and grind the dried astragalus into coarse powder using a grinder; wherein the coarse powder is 50 mesh;

[0065] Step 2, adding the screened astragalus powder to distilled water according to a certain solid-liquid ratio, and extracting in an ultrasonic extraction device; wherein the solid-liquid ratio (w / v) is 1:14, the ultrasonic power is set to 300 W, the extraction temperature is 40° C., and the extraction time is 50 min;

[0066] Step 3, adding the extract obtained in step 2 and cellulase into an enzymatic reaction vessel, performing enzymatic reaction for 3 hours, and after the enzymatic reaction is completed, heating to 95° C. and maintaining for 10 minutes to terminate the enzymatic reaction; wherein the amount of cellulase used is 3wt% of the weight of the astragalus powder, the pH value is adjusted to 5.0, and the temperature is controlled at 50° C.;

[0067] Step 4, mixing the enzymatic hydrolyzate with the specific molecular imprinting polymer of Preparation Example 5, stirring for 1 hour to allow the astragalus polysaccharide to be specifically adsorbed on the specific molecular imprinting polymer, using a mixed solution of water and ethanol to elute the astragalus polysaccharide adsorbed on the specific molecular imprinting polymer, and collecting and concentrating the eluate; wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:1.

[0068] The parameters of each substance in Examples 1 to 5 are shown in Table 3.

[0069] Table 3

[0070]

[0071]

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that in Preparation Example 1, astragalus polysaccharide is directly used as a template molecule.

[0074] Comparative Example 2

[0075] The difference between this comparative example and Example 1 is that the specific molecular imprinting polymer prepared in Preparation Example 6 is used.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 1 is that the specific molecular imprinting polymer prepared in Preparation Example 7 is used.

[0078] Comparative Example 4

[0079] The difference between this comparative example and Example 1 is that the specific molecular imprinting polymer prepared in Preparation Example 8 is used.

[0080] Comparative Example 5

[0081] The difference between this comparative example and Example 1 is that the specific molecular imprinting polymer prepared in Preparation Example 9 is used.

[0082] Comparative Example 6

[0083] The difference between this comparative example and Example 1 is that the specific molecular imprinting polymer prepared in Preparation Example 10 is used.

[0084] Performance Testing

[0085] Test method for extraction rate:

[0086] The astragalus polysaccharide extract was concentrated by rotary evaporation, the weight of the extract was measured, and the extraction rate was calculated as (extract weight / astragalus powder weight)×100%.

[0087] Purity test method:

[0088] The content of polysaccharides in the astragalus polysaccharide extract was determined by high performance liquid chromatography (HPLC), and the purity was calculated as (astragalus polysaccharide content / extract weight)×100%.

[0089] Table 4

[0090]

[0091]

[0092] Combining Examples 1 to 5, Comparative Example 1 and Table 4, it can be seen that the extraction rates of astragalus polysaccharides extracted in Examples 1 to 5 are between 20.5% and 28.4%, and the purities are between 94.2% and 99.2%. From the comparison between Example 1 and Comparative Example 1, it can be seen that the extraction rate and purity of astragalus polysaccharides extracted in Example 1 are significantly higher than those in Comparative Example 1, indicating that the oligosaccharide fragments have specific structural characteristics and can form imprinting sites that are highly matched with astragalus polysaccharides, thereby improving the selective recognition and specific adsorption capabilities of MIPs and enhancing the extraction effect of astragalus polysaccharides.

[0093] It can be seen from Example 1, Comparative Examples 2 to 6 and Table 4 that as the amount of sodium lauryl sulfate added gradually increases, the extraction rate and purity increase respectively. When the amount of sodium lauryl sulfate added reaches 7wt%, the extraction rate and purity reach 26.4% and 99.4% respectively. When the amount of sodium lauryl sulfate added exceeds 7wt%, the extraction rate and purity decrease to varying degrees.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for extracting high-purity astragalus polysaccharide, characterized in that: The steps include: Step 1, wash the astragalus, remove the dust and impurities on the surface, and then dry it in an oven at 50-60° C. to constant weight, and grind the dried astragalus into coarse powder using a grinder; wherein the coarse powder has a mesh size of 40-60; Step 2, adding the screened astragalus powder to distilled water according to a certain solid-liquid ratio, and extracting in an ultrasonic extraction device; Step 3, adding the extract obtained in step 2 and cellulase into an enzymatic reaction vessel, and performing enzymatic reaction for 3 hours. After the enzymatic reaction is completed, heating to 95° C. and maintaining for 10 minutes to terminate the enzymatic reaction; Step 4, mixing the enzymatic hydrolyzate with the specific molecular imprinting polymer, stirring for 1 hour to allow the astragalus polysaccharide to be specifically adsorbed on the specific molecular imprinting polymer, using a mixed solution of water and ethanol to elute the astragalus polysaccharide adsorbed on the specific molecular imprinting polymer, and collecting and concentrating the eluate; wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:

1.

2. The method for extracting high-purity astragalus polysaccharides according to claim 1, characterized in that: The preparation steps of the specific molecular imprinting polymer include the following steps: dissolving a template molecule, a functional monomer, a cross-linking agent, an initiator and a surfactant in an appropriate amount of methanol, performing a free radical polymerization reaction under nitrogen protection, and after the polymerization reaction, eluting the polymer with a mixed solution of ethanol and water to remove the template molecule and obtain the specific molecular imprinting polymer; wherein the reaction temperature is controlled at 60°C, the reaction time is 12 hours, and the volume ratio of water to ethanol in the mixed solution of water and ethanol is 7:

3.

3. The method for extracting high-purity astragalus polysaccharide according to claim 2, characterized in that: The template molecule is an oligosaccharide fragment of astragalus polysaccharide, the functional monomer is acrylamide, the cross-linking agent is ethylene glycol dimethacrylate, and the initiator is potassium persulfate.

4. The method for extracting high-purity astragalus polysaccharide according to claim 1 or 3, characterized in that: The mass ratio of the template molecule, the functional monomer, the cross-linking agent and the initiator is (0.1 to 0.5):(0.2 to 1):(1.0 to 5.0):(0.005 to 0.2).

5. The method for extracting high-purity astragalus polysaccharide according to claim 1, characterized in that: In step 2, the solid-liquid ratio (w / v) is 1:10 to 1:15, the ultrasonic power is set to 200 to 400 W, the extraction temperature is 30 to 50° C., and the extraction time is 30 to 60 min.

6. The method for extracting high-purity astragalus polysaccharide according to claim 1, characterized in that: In step 3, the amount of cellulase used is 2 to 5 wt % of the weight of the astragalus powder, the pH value is adjusted to 5.0, and the temperature is controlled at 40 to 50°C.

7. The method for extracting high-purity astragalus polysaccharide according to claim 2, characterized in that: The surfactant is sodium dodecyl sulfate, and the surfactant accounts for 1% to 10% of the mass of the functional monomer.

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