Method for preparing high-quality cyclocarya paliurus total triterpenoid saponin

Abstract

The invention relates to a method for preparing cyclocarya paliurus total triterpenoid saponin, which comprises the following steps of: sequentially eluting a cyclocarya paliurus crude extract by using an aluminum oxide column, decolorizing by using activated carbon, refrigerating, standing and crystallizing, and adopting an activated aluminum oxide dry-method column chromatography mode to obtain a cyclocarya paliurus total triterpenoid saponin product, the purity and the yield can reach 90% or more, and the cyclocarya paliurus total triterpenoid saponin product is good in taste and pure in sweet taste. Particularly, an activated aluminum particle filler with a large specific surface area and a rich pore structure is prepared, so that on one hand, the total triterpenoid saponins of the cyclocarya paliurus can be effectively enriched, on the other hand, uncomfortable bitter and astringent components in the cyclocarya paliurus can be effectively removed, and on the other hand, impurities such as pesticide residues, heavy metals, plasticizers, pigments, proteins and the like can be effectively removed; the system environment after concentration is facilitated, and crystallization and separation of the cyclocarya paliurus total triterpenoid saponin are facilitated.

Description

Technical Field

[0001] The invention relates to the field of natural product extraction, and in particular to a method for preparing high-quality Cyclocarya paliurus total triterpenoid saponins. Background Art

[0002] Cyclocarya paliurus, a genus of Cyclocarya paliurus in the Juglandaceae family, is a tall, fast-growing tree that is a specialty of my country. It is widely distributed in Jiangxi, Zhejiang, Jiangsu, Anhui, Fujian, Hunan, Hubei, Sichuan, Guizhou, Yunnan and other places. According to the "Chinese Traditional Medicine Resources", its leaves, bark and roots can be used as medicine, with warm nature, spicy and slightly bitter taste, and have the functions of clearing heat and swelling, detoxifying and relieving pain. For a long time, the folks have traditionally taken its leaves to make tea as a beverage, which has the effects of clearing heat and reducing summer heat, lowering blood pressure, treating hypertension and diabetes, and even prolonging life, so it is also called sweet tea tree, magic tea tree, and money tree.

[0003] The most important natural active ingredients in Cyclocarya paliurus are triterpenoids. There are many types of triterpenoids in Cyclocarya paliurus, including triterpenoid saponins and triterpenoid acids.

[0004] The triterpenoid saponins in Cyclocarioside paliurus, such as cyclocarioside I, cyclocarioside II, and cyclocarioside III, are new natural sweeteners that can meet the sweetness needs of patients with hyperglycemia without aggravating their condition. They also have a good effect in lowering blood sugar, lipids, and blood pressure.

[0005] CN102432660A discloses a method for extracting and separating cyclocarya paliurus glycoside I, which comprises crushing dried cyclocarya paliurus leaves, adding biological enzymes for enzymolysis for 1-3 days, adding 8-12 times of 60-90% ethanol solution to the enzymolysis raw materials, soaking and extracting at a temperature of 50-90°C for 1-3 times, concentrating the extract to an extract, adding an appropriate amount of water for dispersion, adding water-saturated n-butanol for extraction 2-4 times, combining the extracts, adding acetone for precipitation, filtering, concentrating and drying the filtrate to obtain a crude extract, adding an appropriate amount of an organic solvent of ethyl acetate and methanol system for reflux extraction, concentrating the extract, cooling, crystallizing, and recrystallizing with anhydrous methanol to obtain cyclocarya paliurus glycoside I. The method involves acetone, n-butanol, and ethyl acetate flammable solvents; and involves ethyl acetate and methanol crystallization and recrystallization, with large solvent residues, and is not suitable for higher requirements for medicinal and cosmetic uses, and the use of the product is limited.

[0006] CN109364119A discloses a method and application for preparing total triterpenes with hypoglycemic effect from Cyclocarya paliurus leaves, which uses Cyclocarya paliurus leaves as raw materials, extracts through ethanol-water mixed solvent, extracts through organic solvent liquid-liquid, elutes through polyamide column chromatography with organic solvent, and elutes through macroporous resin column chromatography with ethanol-water, to obtain total triterpenes of Cyclocarya paliurus. The content of total triterpenes of Cyclocarya paliurus obtained by this method is low, and a large amount of flammable and explosive organic solvents are used, which is not suitable for industrial production.

[0007] CN110917240A discloses a continuous method for separating multiple active ingredients from Cyclocarya paliurus, and the steps are as follows: using Cyclocarya paliurus dry leaves as raw materials, obtaining Cyclocarya paliurus triterpenoid saponins with a content of more than 88% through alkaline water percolation, centrifugation, non-polar macroporous resin adsorption, elution, decolorization and other steps; adjusting the pH value of the non-polar macroporous resin column effluent to neutral, medium polar or polar macroporous resin adsorption, elution, and other steps to obtain Cyclocarya paliurus flavonoids; the medium polar or polar macroporous resin column effluent is subjected to nanofiltration, decolorization, reduced pressure concentration and other steps to obtain Cyclocarya paliurus polysaccharides. This method uses a relatively large amount of alkali and acid, and the damage to the active ingredients of Cyclocarya paliurus is also relatively strong, resulting in unnecessary losses.

[0008] CN112870254A discloses a method for separating flavonoids, saponins and polysaccharides from Cyclocarya paliurus by a continuous method, and the steps are as follows: using Cyclocarya paliurus dry leaves as raw materials, enzymatic hydrolysis, high-concentration low-carbon alcohol percolation extraction, ceramic membrane filtration, anion and cation exchange resin column decolorization, desalination, polyester amide resin adsorption of flavonoids, and effluent concentration and drying to obtain a product with a Cyclocarya paliurus saponin content of 90%. This method uses a large amount of high-concentration low-carbon alcohol, and the solvent cannot be reused for a second time, the production cost is high, and the flavonoids are separated by polyester amide resin column, and the plasticizer residue and solvent residue of the Cyclocarya paliurus saponin product obtained cannot be guaranteed.

[0009] Currently, the extracts of Cyclocarya paliurus on the market often have an unpleasant bitter and astringent taste. In addition, in order to completely remove the pesticide residues and heavy metal trace components in the product, special pesticide removal resins or metal chelating agents are often used to completely remove these harmful impurities, but this will lead to a decrease in the yield of total triterpenoid saponins of Cyclocarya paliurus. Therefore, it is necessary to develop a method for preparing total triterpenoid saponins of Cyclocarya paliurus, which has a good taste, pure sweetness, no pesticide, heavy metal, organic solvent and plasticizer residues, and a high yield. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a method for preparing high-quality total triterpenoid saponins of Cyclocarya paliurus, which has a good taste and removes pesticide residues, heavy metals, organic solvents and plasticizers. The method of the present invention has a simple process and strong industrialization ability, and is of great significance for improving the product quality of total triterpenoid saponins of Cyclocarya paliurus, ensuring product safety, and the research and application of natural sweetener resources of Cyclocarya paliurus. The technical solution adopted by the present invention to solve its technical problem is as follows:

[0011] A method for preparing total triterpenoid saponins of Cyclocarya paliurus, comprising the following steps:

[0012] (1) Pretreatment: The dry leaves of Cyclocarya paliurus are crushed and sieved.

[0013] (2) Preparation of a crude extract of Cyclocarya paliurus: Adding ethanol aqueous solution to the Cyclocarya paliurus raw material obtained in step (1) and performing continuous ultrasonic countercurrent extraction to obtain a Cyclocarya paliurus extract; concentrating, drying, crushing, and sieving the extract to obtain a crude extract of Cyclocarya paliurus.

[0014] (3) Alumina sample mixing: The crude extract of Cyclocarya paliurus obtained in step (2) is dispersed and dissolved in ethanol to form an extract, activated alumina particles are added, and the mixture is dried to obtain alumina sample mixing.

[0015] (4) Column loading: first loading activated alumina particles into the body of the chromatography column, and then loading the sample-mixed alumina obtained in step (3) to obtain an activated alumina chromatography column;

[0016] (5) Elution from alumina column: The alumina column is eluted with an eluent, and the target elution effluent is collected, concentrated, and dried to obtain a purified product of total triterpenoid saponins from Cyclocarya paliurus.

[0017] (6) Activated carbon decolorization: The purified total saponin of Cyclocarya paliurus obtained in step (5) is dissolved in 70% ethanol to a 10% solid concentration solution, and activated carbon is added. The mixture is stirred while warm and filtered while hot to obtain a filtrate.

[0018] (7) Crystallization: In step (6), the filtrate obtained is concentrated under reduced pressure, and then refrigerated and allowed to stand for crystallization, and crystals are separated and dried to obtain total triterpenoid saponins of Cyclocarya paliurus with a purity of more than 80%.

[0019] Preferably, in step (1), the mesh size of the sieve is 10-20 meshes.

[0020] Preferably, in step (2), the continuous countercurrent ultrasonic extraction is carried out for 1.5 to 4 hours at an extraction temperature of 30 to 60° C., an ultrasonic power of 200 to 300 W, and a frequency of 25 to 60 kHz, and the alcohol concentration in the ethanol aqueous solution is 50 to 80 wt %.

[0021] Preferably, in step (3) and step (4), the activated alumina particles have a particle size of 5-10 μm; the activated alumina particles are obtained by a preparation method comprising the following steps:

[0022] (S1) mixing organic aluminum (in terms of Al), n-butanol, ethanol, water, ethyl acetoacetate, and polyol in a molar ratio of 1:3-5:7-11:3-5:1-2:1-3, and stirring at 50-70° C. to obtain aluminum sol;

[0023] (S2) preparing ammonia water, ethanol and formamide into a solution A with an ammonia concentration of 5-10wt%, an ethanol concentration of 20-30wt% and a formamide concentration of 1-3wt%;

[0024] (S3) pushing the aluminum sol obtained in step (S1) and the solution A obtained in step (S2) into a mixer in a volume ratio of 1-1.5:1 through a syringe pump for mixing, and then squeezing the mixture into the oil phase through a pinhole nozzle to form gel beads;

[0025] (S4) The gel beads are aged, dried by supercritical fluid, and calcined to obtain activated alumina particles.

[0026] The activated alumina particles obtained by the above-mentioned preparation method of the present invention have a rich pore structure and a large specific surface area. The supercritical drying technology is used to avoid the agglomeration of particles and the collapse of pores. The inventor unexpectedly found that the activated alumina obtained by the above-mentioned preparation method is used as a chromatography column filler to prepare the total triterpenoid saponins of Cyclocarya paliurus, which can fully adsorb pesticide residues and heavy metals without the need for anion and cation exchange resins or special resins for removing pesticide residues. The pesticide residues and heavy metals in the obtained product are basically removed, and the yield is not affected.

[0027] Furthermore, in step (S1), the organic aluminum is selected from at least one of aluminum isopropoxide and aluminum sec-butoxide, and the polyol is selected from at least one of polyethylene glycol and polypropylene glycol having a number average molecular weight of 500-1000.

[0028] Furthermore, in step (S4), the aging is performed by placing the gel beads in ethanol, replacing the ethanol every 6-10 hours for 24-48 hours; the supercritical drying is performed by using ethanol as the medium, the system temperature is 6-8MPa, the pressure is 240-280°C, and the supercritical drying treatment time is 1-2 hours. After the supercritical treatment is completed, the pressure is slowly restored to normal pressure, nitrogen is purged to remove ethanol vapor, and a precursor is obtained after cooling. The precursor is calcined at 900-1100°C for 2-4 hours to obtain activated alumina particles.

[0029] Preferably, in step (3), the amount of activated alumina particles is 1-2 times the weight of the crude extract of Cyclocarya paliurus; in step (4), the amount of activated alumina particles is 5-8 times the weight of the crude extract of Cyclocarya paliurus, and the height-to-diameter ratio of the alumina chromatography column is 8 to 20:1.

[0030] Preferably, in step (5), the eluent is a mixed solution of ethyl acetate and ethanol in a volume ratio of 20 / 80 to 50 / 50, the amount of the eluent is 5 to 20 BV, and the elution flow rate is 0.5 to 2 BV / hour.

[0031] Preferably, in step (6), the amount of activated carbon used is 5-10% of the weight of the solid content of the target eluate of Cyclocarya paliurus, the insulation temperature is 65-75° C., and the time is 2-4 h.

[0032] Preferably, in step (7), the filtrate is concentrated under reduced pressure to a solid concentration of 15-25%, a crystallization temperature of 0-5°C, and a crystallization time of 24-36h.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] The method of the present invention adopts an activated alumina dry column chromatography method, and through a specific method and raw material ratio, an activated active aluminum particle filler with a large specific surface area and a rich pore structure is prepared. On the one hand, it can effectively enrich the total triterpenoid saponins of Cyclocarya paliurus, and secondly, it can effectively remove the unpleasant bitter and astringent components in Cyclocarya paliurus, and thirdly, it can effectively remove impurities such as pesticide residues, heavy metals, plasticizers, pigments, proteins, etc., which is conducive to the system environment after concentration and is more conducive to the crystallization and separation of the total triterpenoid saponins of Cyclocarya paliurus. The method of the present invention adopts a low-temperature water phase crystallization method in the process of the method of the present invention, and the solvent residue of the obtained high-quality total triterpenoid saponins product of Cyclocarya paliurus is not detected. The total triterpenoid saponins product of Cyclocarya paliurus obtained by the present invention: the purity and yield can reach more than 90%, the taste is good, and the sweetness is pure. DETAILED DESCRIPTION

[0035] To make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be described in detail below. The following examples are convenient for better understanding of the present invention, but are not intended to limit the present invention. The experimental methods in the following examples are conventional methods unless otherwise specified.

[0036] The Cyclocarya paliurus dry leaf raw material used in the present invention has a total triterpenoid saponin content of 8.13%.

[0037] Preparation Example 1

[0038] (S1) mixing aluminum isopropoxide, n-butanol, ethanol, water, ethyl acetoacetate, and PEG600 in a molar ratio of 1:5:10:5:1:2, and stirring at 60° C. for 1 h to obtain aluminum sol;

[0039] (S2) preparing ammonia water, ethanol and formamide into a solution A with an ammonia concentration of 8 wt %, an ethanol concentration of 20 wt % and a formamide concentration of 3 wt %;

[0040] (S3) pushing the aluminum sol obtained in step (S1) and the solution A obtained in step (S2) into a mixer in a volume ratio of 1:1 through a syringe pump for mixing, and then squeezing the mixture into soybean oil through a pinhole nozzle to form gel beads;

[0041] (S4) The gel beads were placed in ethanol with a mass ratio of 10 times, and the ethanol was replaced every 8 hours, and replaced 3 times for a total of 24 hours. Ethanol was used as the medium for supercritical fluid drying. The supercritical drying process conditions were a pressure of 7.5 MPa and a temperature of 260°C for supercritical treatment for 1 hour to obtain a precursor. The precursor was transferred to a muffle furnace and heated to 1050°C at a heating rate of 10°C / min. It was calcined for 4 hours to obtain activated alumina, which was then ground and sieved to obtain activated alumina particles with an average particle size of about 8 μm.

[0042] Example 1

[0043] (1) The dried leaves of Cyclocarya paliurus were crushed and 1000 g of the material under a 10-mesh sieve was weighed.

[0044] (2) extracting 1000 g of the sieve material obtained in step (1) with 10 L of 50% ethanol under continuous countercurrent ultrasonic extraction at 40° C. for 2 h, wherein the ultrasonic power is 200 W and the frequency is 25 kHz. After extraction, filtering is performed to obtain an extract; the extract is concentrated at 70° C., dried, crushed, and passed through a 40-mesh sieve to obtain a crude extract of Cyclocarya paliurus.

[0045] (3) The crude extract of Cyclocarya paliurus was dispersed and dissolved in ethanol to form an extract, and 1.5 times the weight of the crude extract was added to prepare activated alumina particles in Preparation Example 1, and the particles were dried with forced air at 60° C. to constant weight to obtain mixed alumina.

[0046] (4) First, the activated alumina particles prepared in Preparation Example 1 were loaded into the column body of the chromatography column at a weight of 10 times that of the crude extract of Cyclocarya paliurus, and then the mixed alumina was loaded to obtain an activated alumina chromatography column with a height-to-diameter ratio of 10:1;

[0047] (5) Elution from an alumina column: The alumina column was eluted with an eluent (a mixed solvent of 8 BV ethyl acetate and ethanol in a volume ratio of 20 / 80) at a flow rate of 1 BV / hour. The effluent containing Cyclocarya paliurus glycosides was collected by silica gel thin layer chromatography (TLC), concentrated, and dried to obtain a purified Cyclocarya paliurus product.

[0048] (6) Activated carbon decolorization: Use 70% ethanol to dissolve the purified Cyclocarya paliurus into a solution with a solid concentration of 10%, add activated carbon in an amount of 10% by weight of the purified Cyclocarya paliurus, keep warm and stir at 70°C for 2 h, and filter while hot to obtain a filtrate.

[0049] (7) Crystallization: The filtrate is concentrated under reduced pressure to a solid concentration of 20%, and then refrigerated at 0-5°C for 24 hours to allow crystallization to proceed. The crystals are separated and dried to obtain the total triterpenoid saponins product of Cyclocarya paliurus.

[0050] Example 2

[0051] (1) The dried leaves of Cyclocarya paliurus were crushed and 1000 g of the material was sieved through a 20-mesh sieve.

[0052] (2) extracting 1000 g of the sieve material obtained in step (1) with 10 L of 70% ethanol under countercurrent continuous ultrasonic extraction at 50° C. for 3 h, wherein the ultrasonic power is 200 W and the frequency is 25 kHz. After extraction, filtering is performed to obtain an extract; the extract is concentrated at 70° C., dried, crushed, and passed through a 40-mesh sieve to obtain a crude extract of Cyclocarya paliurus.

[0053] (3) The crude extract of Cyclocarya paliurus was dispersed and dissolved in ethanol to form an extract, and 1.2 times the weight of the crude extract was added to prepare the activated alumina particles in Preparation Example 1, and the particles were dried with forced air at 60° C. to a constant weight to obtain mixed alumina.

[0054] (4) First, the activated alumina particles prepared in Preparation Example 1 in an amount of 15 times the weight of the crude extract of Cyclocarya paliurus were loaded into the column body of the chromatography column, and then the sample-mixing alumina was loaded to obtain an activated alumina chromatography column having a height-to-diameter ratio of 15:1;

[0055] (5) Elution from alumina column: The alumina column was eluted with an eluent (a mixed solvent of 15 BV ethyl acetate and ethanol in a volume ratio of 30 / 70) at a flow rate of 1.5 BV / hour. The effluent containing Cyclocarya paliurus glycosides was collected by silica gel thin layer chromatography (TLC) detection, concentrated, and dried to obtain a purified Cyclocarya paliurus product.

[0056] (6) Activated carbon decolorization: Use 70% ethanol to dissolve the purified Cyclocarya paliurus into a solution with a solid concentration of 10%, add activated carbon in an amount of 10% by weight of the purified Cyclocarya paliurus, keep warm and stir at 60°C for 3 hours, and filter while hot to obtain a filtrate.

[0057] (7) Crystallization: The filtrate is concentrated under reduced pressure to a solid concentration of 25%, and then refrigerated at 0-5°C for 30 hours to allow crystallization to proceed. The crystals are separated and dried to obtain the total triterpenoid saponins product of Cyclocarya paliurus.

[0058] Example 3

[0059] (1) The dried leaves of Cyclocarya paliurus were crushed and 1000 g of the material under a 10-mesh sieve was weighed.

[0060] (2) extracting 1000 g of the sieve material obtained in step (1) with 10 L of 70% ethanol under countercurrent continuous ultrasonic extraction at 60° C. for 3 h, wherein the ultrasonic power is 200 W and the frequency is 25 kHz. After extraction, filtering is performed to obtain an extract; the extract is concentrated at 70° C., dried, crushed, and passed through a 40-mesh sieve to obtain a crude extract of Cyclocarya paliurus.

[0061] (3) The crude extract of Cyclocarya paliurus was dispersed and dissolved in ethanol to form an extract, and activated alumina particles were prepared by adding 1 times the weight of the crude extract in Preparation Example 1, and dried with forced air at 60° C. to constant weight to obtain mixed alumina.

[0062] (4) First, the activated alumina particles prepared in Preparation Example 1 in an amount 15 times the weight of the crude extract of Cyclocarya paliurus were loaded into the column body of the chromatography column, and then the sample-mixing alumina was loaded to obtain an activated alumina chromatography column with a height-to-diameter ratio of 15:1;

[0063] (5) Elution from alumina column: The alumina column was eluted with an eluent (a mixed solvent of 15 BV ethyl acetate and ethanol in a volume ratio of 40 / 60) at a flow rate of 1 BV / hour. The effluent containing Cyclocarya paliurus glycosides was collected by silica gel thin layer chromatography (TLC), concentrated, and dried to obtain a purified Cyclocarya paliurus product.

[0064] (6) Activated carbon decolorization: The purified Cyclocarya paliurus was dissolved in 70% ethanol to a solution with a solid concentration of 10%, and activated carbon in an amount of 8% by weight of the purified Cyclocarya paliurus was added. The mixture was stirred at 70° C. for 4 h and filtered while hot to obtain a filtrate.

[0065] (7) Crystallization: The filtrate is concentrated under reduced pressure to a solid concentration of 25%, and then refrigerated at 0-5°C for 36 hours to allow crystallization to proceed. The crystals are separated and dried to obtain the total triterpenoid saponins product of Cyclocarya paliurus.

[0066] Comparative Example 1

[0067] The other conditions are the same as those in Example 3, except that in steps (3) and (4), the activated alumina particles obtained in Preparation Example 1 are replaced by ordinary commercially available neutral alumina fillers.

[0068] The total triterpenoid saponins product of Cyclocarya paliurus obtained by the present invention is tested as shown in Table 1:

[0069] Table 1 Test of total triterpenoid saponins of Cyclocarya paliurus

[0070]

[0071]

[0072] It can be seen from the data in Table 1 that the present invention substantially removes pesticide residues, heavy metals and plasticizer residues by making the activated alumina filler by itself, and has no obvious adverse effect on the yield.

Claims

1. A method for preparing total triterpenoid saponins of Cyclocarya paliurus, characterized in that: The following steps are involved: (1) Pretreatment: the dry leaves of Cyclocarya paliurus are crushed and sieved; (2) Preparation of a crude extract of Cyclocarya paliurus: adding an ethanol aqueous solution to the Cyclocarya paliurus raw material obtained in step (1) for continuous ultrasonic countercurrent extraction to obtain a Cyclocarya paliurus extract, and concentrating, drying, pulverizing, and sieving the extract to obtain a crude extract of Cyclocarya paliurus; (3) Alumina sample mixing: the crude extract of Cyclocarya paliurus obtained in step (2) is dispersed and dissolved in ethanol to form an extract, activated alumina particles are added, and the mixture is dried to obtain alumina sample mixing; (4) Column loading: first loading activated alumina particles into the body of the chromatography column, and then loading the sample-mixed alumina obtained in step (3) to obtain an activated alumina chromatography column; (5) Elution from an alumina column: eluting the alumina column with an eluent, collecting the target elution effluent, concentrating and drying to obtain a purified product of total triterpenoid saponins from Cyclocarya paliurus; (6) Activated carbon decolorization: The purified total saponin of Cyclocarya paliurus obtained in step (5) is dissolved in 70% ethanol to a 10% solid concentration solution, activated carbon is added, the mixture is stirred while warm, and filtered while hot to obtain a filtrate; (7) Crystallization: In step (6), the filtrate obtained is concentrated under reduced pressure, and then refrigerated and allowed to stand for crystallization, and crystals are separated and dried to obtain total triterpenoid saponins of Cyclocarya paliurus with a purity of more than 80%.

2. The preparation method according to claim 1, characterized in that: In step (1), the mesh size of the sieve is 10-20 meshes.

3. The preparation method according to claim 1, characterized in that: In step (2), the continuous countercurrent ultrasonic extraction is carried out for 1.5 to 4 hours at an extraction temperature of 30 to 60° C., an ultrasonic power of 200 to 300 W, and a frequency of 25 to 60 kHz, and the alcohol concentration in the ethanol aqueous solution is 50 to 80 wt %.

4. The preparation method according to claim 1, characterized in that: In step (3) and step (4), the activated alumina particles have a particle size of 5-10 μm; the activated alumina particles are obtained by a preparation method comprising the following steps: (S1) mixing organic aluminum (in terms of Al), n-butanol, ethanol, water, ethyl acetoacetate, and polyol in a molar ratio of 1:3-5:7-11:3-5:1-2:1-3, and stirring at 50-70° C. to obtain aluminum sol; (S2) preparing ammonia water, ethanol and formamide into a solution A with an ammonia concentration of 5-10wt%, an ethanol concentration of 20-30wt% and a formamide concentration of 1-3wt%; (S3) pushing the aluminum sol obtained in step (S1) and the solution A obtained in step (S2) into a mixer by a syringe pump in a volume ratio of 1-1.5:1 and then squeezing the mixture into the oil phase through a pinhole nozzle to form gel beads; (S4) The gel beads are aged, dried by supercritical fluid, and calcined to obtain activated alumina particles.

5. The preparation method according to claim 4, characterized in that: In step (S1), the organic aluminum is selected from at least one of aluminum isopropoxide and aluminum sec-butoxide, and the polyol is selected from at least one of polyethylene glycol and polypropylene glycol having a number average molecular weight of 500-1000.

6. The preparation method according to claim 4, characterized in that: In step (S4), aging is performed by placing the gel beads in ethanol, replacing the ethanol every 6-10 hours for 24-48 hours; supercritical drying is performed by using ethanol as a medium, the system temperature is 6-8MPa, the pressure is 240-280°C, and the supercritical drying treatment time is 1-2 hours. After the supercritical treatment is completed, the pressure is slowly returned to normal pressure, nitrogen is purged to remove ethanol vapor, and a precursor is obtained after cooling. The precursor is calcined at 900-1100°C for 2-4 hours to obtain activated alumina particles.

7. The preparation method according to claim 1, characterized in that: In step (3), the amount of activated alumina particles is 1-2 times the weight of the crude extract of Cyclocarya paliurus; in step (4), the amount of activated alumina particles is 5-8 times the weight of the crude extract of Cyclocarya paliurus, and the height-to-diameter ratio of the alumina chromatography column is 8 to 20:

1.

8. The preparation method according to claim 1, characterized in that: In step (5), the eluent is a mixed solution of ethyl acetate and ethanol in a volume ratio of 20 / 80 to 50 / 50, the amount of the eluent is 5 to 20 BV, and the elution flow rate is 0.5 to 2 BV / hour.

9. The preparation method according to claim 1, characterized in that: In step (6), the amount of activated carbon used is 5-10% of the weight of the solid content of the target eluate of Cyclocarya paliurus, the insulation temperature is 65-75° C., and the time is 2-4 hours.

10. The preparation method according to claim 1, characterized in that: In step (7), the filtrate is concentrated under reduced pressure to a solid concentration of 15-25%, a crystallization temperature of 0-5°C, and a crystallization time of 24-36h.

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