Template molecule, molecularly imprinted polymer and application of molecularly imprinted polymer in separation of saponin compounds

Abstract

The invention relates to a template molecule, a molecularly imprinted polymer and application of the molecularly imprinted polymer in separation of saponin compounds. The molecularly imprinted polymer uses a virtual template molecule. According to the template molecule, the selective recognition capability of the molecularly imprinted polymer on specific types of saponin compounds is remarkably improved. The method can be used for separating, enriching and purifying natural saponin compounds such as ginsenoside Rb1, panax japonicus saponin IV, kochia saponin II, platycodin D, saikoside A, aralia elatoside A, aralia elatoside B, aralia elatoside C, aescin, ziyuglycoside II, ziyuglycoside I and kochia saponin IC in a natural product extracting solution, and is high in enrichment degree, high in accuracy and wide in application range.

Description

Technical Field

[0001] The invention belongs to the technical field of plant component purification, and in particular relates to a template molecule, a molecular imprinting polymer and applications thereof in separating saponin compounds. Background Art

[0002] The roots, stems and leaves of ginseng of the Araliaceae family can be used to obtain ginsenosides after fine extraction and processing. Ginsenosides contain eighteen kinds of ginsenoside monomers. The sources of ginsenosides are scarce, and the extraction technology is complicated. In recent years, molecular imprinting technology has been widely used in the field of enrichment and purification with remarkable results. It has opened up a new way for the enrichment and purification of saponins including ginsenosides. In the promotion and application of molecular imprinting technology, the key obstacle is the high cost, among which the high cost of template molecules accounts for a considerable proportion of the extraction cost. In addition, the structure of ginsenosides is complex and diverse, and the separation and purification technology is complex. The preparation cost of high-purity ginsenoside monomers is even higher. Summary of the invention

[0003] The first object of the present invention is to provide a template molecule to reduce the extraction cost by designing a virtual template molecule.

[0004] The second object of the present invention is to provide a molecularly imprinted polymer prepared by the above template molecule.

[0005] The third object of the present invention is to provide the application of the molecularly imprinted polymer.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A template molecule with the following structural formula:

[0008]

[0009] The molecularly imprinted polymer prepared by the above template molecule comprises the following steps:

[0010] Prepare dispersed phase: mix hydrophilic functional monomer, crosslinking agent, water and template molecule to prepare solution A;

[0011] Prepare the continuous phase: mix the emulsifier with n-hexane under an inert gas atmosphere to form a continuous phase as solution B;

[0012] Preparation of inverse dispersion system: Mix solution A and solution B under an inert gas atmosphere to obtain a white emulsion;

[0013] Polymerization reaction: Mix the white latex with the initiator to obtain a polymer microsphere mixture;

[0014] Post-treatment: Mix the polymer microsphere mixture with methanol, filter out the precipitate, wash the precipitate to neutrality after eluting the template molecules, and then dry it to constant weight to obtain molecularly imprinted polymer microspheres.

[0015] As a preferred embodiment of the present invention, in preparing the dispersed phase, the hydrophilic functional monomer is one of acrylic acid, allylamine and methacrylic acid.

[0016] As a preferred embodiment of the present invention, in preparing the dispersed phase, the crosslinking agent is at least one of N,N'-methylenebisacrylamide, trimethoxypropyl trimethacrylate and divinylbenzene.

[0017] As a preferred embodiment of the present invention, in preparing the dispersed phase, the molar ratio of the hydrophilic functional monomer to the template molecule is 1:4.5-7.5.

[0018] As a preferred embodiment of the present invention, in the preparation of the continuous phase, the emulsifier is at least one of docusate sodium, octylphenol polyoxyethylene ether, and Triton X-100.

[0019] As a preferred embodiment of the present invention, in the polymerization reaction, the initiator is one of potassium persulfate and ammonium persulfate.

[0020] As a preferred embodiment of the present invention, in the polymerization reaction, the polymerization reaction temperature is 35-80°C.

[0021] As a preferred embodiment of the present invention, in the polymerization reaction, the polymerization reaction time is 1 to 4 hours, and stirring is continued during the polymerization reaction.

[0022] The use of the above-mentioned molecular imprinting polymer in separating natural saponin compounds is characterized in that the natural saponin compound is one of ginsenoside Rb1, ginsenoside IV, kochia scoparia saponin II, platycodon saponin D, bupleurosaponin A, amaranthin A, amaranthin B, amaranthin C, aescin, sanguisorbaside II, sanguisorbaside I, and kochia scoparia saponin IC.

[0023] Beneficial effects of the present invention:

[0024] The molecular imprinted polymer of the present invention uses ethyl-6-((-8a-(ethoxycarbonyl)-4,4,6a,6b,11,11,14b-heptamethyl-1,2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-eicosyl)oxy)-(2S,3R,4S,5S,6R)-3,4,5-trihydroxytetrahydro-2H-pyran-2-carboxylate as a template molecule. The monomer of the template molecule, by virtue of its built-in hydrogen bond receptor and significant electronic effect, constructs a strong intermolecular force with a specific saponin compound molecule and shapes a more selective spatial structure, thereby significantly improving the selective recognition ability of the molecular imprinted polymer for a specific type of saponin compound. It overcomes the problem of high-purity natural saponin target molecules being relatively expensive, can be used for large-scale preparation of molecular imprinting polymers, and significantly reduces the extraction cost of natural saponin compounds.

[0025] The molecularly imprinted polymer of natural saponin compounds prepared by the preparation method of the present invention can increase the adsorption amount of target molecules and improve the purity of natural saponin compounds during application, and can be used for separation, enrichment and purification of natural saponin compounds in natural product extracts, with high enrichment, strong accuracy and wide application range. The molecularly imprinted polymer has good adsorption performance for natural saponin compound molecules of ginsenoside Rb1, ginsenoside IV, kochia scoparia saponin II, platycodon saponin D, bupleurosaponin A, aralia glycoside A, aralia glycoside B, aralia glycoside C, aescin, sanguisorbaside II, sanguisorbaside I and kochia scoparia saponin IC, and has broad application prospects in the preparation and detection of natural saponin compounds. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific implementation methods.

[0027] Example 1

[0028] A template molecule is prepared: ethyl-6-((-8a-(ethoxycarbonyl)-4,4,6a,6b,11,11,14b-heptamethyl-1,2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-eicosyl)oxy)-(2S,3R,4S,5S,6R)-3,4,5-trihydroxytetrahydro-2H-pyran-2-carboxylate, the structural formula of which is as follows:

[0029]

[0030] The specific experimental operations are as follows:

[0031] (1) Add 10.0 mmol of D-glucose and 10 mL of acetic anhydride to a round-bottom flask to obtain a mixture, and cool the mixture to 0°C. Then, add 0.1 m perchloric acid (70 wt%) dropwise to the mixture while stirring. After the addition is completed, continue stirring at 0°C for 5 h to obtain a reaction solution. Dilute the reaction solution with dichloromethane (40 mL). Then, add water (20 mL), saturated NaHCO 3 The diluted reaction solution was washed with 1% ethanol (20 mL) and brine (20 mL). The organic layer was dried over anhydrous sodium sulfate, and then the organic solvent in the organic layer was removed by a rotary evaporator to obtain acetyl-protected glucose with a yield of 95%.

[0032] (2) Add 4.0 mmol of acetyl-protected glucose and 40 mL of dichloromethane to a round-bottom flask to obtain a mixed solution, and add 1.66 mL of 48% mass fraction boron trifluoride ether solution (Article No.: Titan Technology 01375737) to the mixed solution at 0°C. Continue to stir the mixture at 0°C for 10 minutes, then add 5.2 mmol of compound B oleanolic acid to the mixture. Then continue to stir at room temperature for 24 hours. After the reaction is completed, cool to 0°C, and add 20 mL of saturated NaHCO to the mixture at 0°C. 3 The aqueous solution was washed with water (20 mL x 3). After separation, the aqueous layer was further extracted with 40 mL of dichloromethane. The dichloromethane organic phases were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. Compound C was obtained after column chromatography purification with a yield of 89%.

[0033] (3) 2.5 mmol of compound C was dissolved in a mixture of 25 mL of methanol and 5.0 mL of 25% by mass aqueous ammonia solution, stirred at room temperature for 24 hours, and then the solvent was removed under reduced pressure. Compound D was obtained after column chromatography purification with a yield of 96%.

[0034] (3) 2.0 mmol of compound D, 10 mL of deionized water and 10 mL of acetonitrile were added to a round-bottom flask. Then, 0.6 mmol of 2,2,6,6-tetramethylpiperidinyl oxide (TEMPO), 4.4 mmol of iodophenyl diacetic acid and 4.0 mmol of NaHCO were added to the reaction system under stirring at 0°C. 3 The obtained mixture was heated to room temperature and stirred for 2 hours. After the reaction was completed, 0.5 mL of ethanol was added to the reaction bottle to quench the reaction, and then the reaction solution was washed once with 10 mL of ethyl acetate. The aqueous phase was taken, the pH of the aqueous phase was adjusted to 6.0, the solvent was removed under reduced pressure, and the compound E was purified by column chromatography with a yield of 78%.

[0035] (4) 1.5 mmol of compound E and 10 mL of ethanol were added to a round-bottom flask, followed by the addition of 5 drops of concentrated sulfuric acid. The mixture was refluxed for 8 hours. After the reaction was completed, 20 mL of water was added to the reaction system, and the ethanol was removed under reduced pressure. The aqueous phase was extracted with ethyl acetate (10 mL×3). The ethyl acetate phases were combined and concentrated under reduced pressure to remove the solvent to obtain a crude product. The target template molecule was purified by column chromatography in a yield of 89%.

[0036] The data is as follows: 1 H NMR (400 MHz, DMSO-d 6 )δ5.21-5.09(m,1H),4.31-4.16(m,2H),4.15-4.09(m,4H),3.59-3.42( m,1H),3.32-3.19(m,1H),3.17-3.15(m,2H),2.71-2.56(m,1H),1.92-1. 72(m,1H),1.65-1.59(m,4H),1.53-1.42(m,16H),1.42-1.36(m,4H),1.2 1-0.92(m,4H),0.97-0.85(m,6H),0.82-0.75(m,9H),0.72-0.69(m,8H). 13 C NMR (101 MHz, DMSO-d 6 )δ179.1,171.3,144.3,122.0,106.0,88.6,76.7,76.0,74.2,72.1,61.8(2C),55.4,47.5,46.2,45.9(2C),41.8(2C),41.3,39 .2,38.5,36.8(2C),33.8,33.3,30.9(2C),28.0,27.7,26.0,23.9(2C),23.4,23.1,17.3,16.9,15.6,14.5(2C).HRMS(ESI)m / z calcd for C 40 H 64 O 9 [M+H] + :689.4268,found:689.4264.

[0037] Example 2 Preparation and performance testing of molecularly imprinted polymers

[0038] 1. Prepare molecularly imprinted polymers, the steps are as follows:

[0039] 1.1 Preparation of dispersed phase: 5.5 mmol allylamine and 27.5 mmol N, N'-methylenebisacrylamide (MBA) were dissolved in 30 mL water, and 1 mmol of the template molecule ethyl-6-((-8a-(ethoxycarbonyl)-4,4,6a,6b,11,11,14b-heptamethyl-1,2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-eicosyl)oxy)-(2S,3R,4S,5S,6R)-3,4,5-trihydroxytetrahydro-2H-pyran-2-carboxylate prepared in Example 1 was added, uniformly dispersed, and magnetically stirred at room temperature for 0.5 h to form a prepolymer to obtain solution A;

[0040] 1.2 Preparation of continuous phase: Dissolve 30 g of sodium docusate (AOT) in 300 mL of n-hexane under nitrogen atmosphere to form a continuous phase as solution B;

[0041] 1.3 Preparation of reverse phase dispersion system: slowly transfer solution A to solution B under stirring, and stir at room temperature for 60 min under nitrogen atmosphere to obtain a white emulsion;

[0042] 1.4 Polymerization reaction: 0.7 mL of 10% (w / v) ammonium persulfate (APS) was added to the white emulsion to initiate the polymerization reaction, and the reaction was continued at 65° C. and 350 r / min for 2 h to obtain a polymer microsphere mixture;

[0043] 1.5 Post-treatment: Methanol was added to the polymer microsphere mixture to aggregate and precipitate the polymer, and the polymer was filtered to obtain the polymer. The mixture was transferred to a 250-mesh sieve, washed with water to remove fine powder, and then dried. The dried polymer was placed in a Soxhlet extractor, and the template molecules in the polymer were extracted with methanol / glacial acetic acid (9:1, V / V). The polymer was vacuum dried at 60°C to constant weight. After drying, the imprinted materials were classified with sieves of different mesh sizes to obtain molecular imprinted polymers of different sizes.

[0044] 2. Performance Testing

[0045] 2.1 Study on the adsorption performance of ginsenoside Rb1:

[0046] i) Total saponin detection method (for simplified characterization of ginsenoside Rb1): Prepare 1.0 mg / mL ginsenoside Rb1 standard solution with methanol as solvent, accurately pipette 20 μL, 40 μL, 80 μL, 120 μL, 160 μL, and 200 μL of reference solution, place in stoppered test tubes, place in boiling water bath to remove solvent, add 0.5 mL of 1 wt% vanillin perchloric acid test solution, place in 60°C constant temperature water bath to mix thoroughly, heat for 15 minutes, immediately cool with ice water for 2 minutes, add 5 mL of 77% sulfuric acid solution, shake well; use reagent as blank. After eliminating bubbles, use UV-visible spectrophotometer to measure absorbance at a wavelength of 540 nm, and draw a standard curve with absorbance as ordinate and concentration as abscissa. Dilute the sample to be tested with methanol to a concentration of 20-200 μg / mL, take 1 mL for detection, and calculate the content through the standard curve.

[0047] ii) Determination of adsorption amount: Accurately weigh 0.2g of molecularly imprinted nanospheres and place them in a ground-mouth conical flask, add 5.0mL of ginsenoside Rb1 methanol solution with a concentration of 3mg / mL, and adsorb at a constant temperature for 5h after oscillation. Centrifuge and dilute the supernatant with methanol to a concentration of 20-200μg / mL. Determine the absorbance three times in parallel according to method i, take the arithmetic mean, and calculate the total saponin concentration using the standard curve. The adsorption amount of the imprinted polymer (61.2mg / g) was calculated based on the change in the total saponin concentration in the solution before and after adsorption. Calculation formula:

[0048] Q=(C 0 -C)*V / W

[0049] Where: Q: adsorption amount per gram of polymer (mg / g);

[0050] C 0 : the original mass concentration of the adsorbed compound in the equilibrium adsorption experiment (mg / L);

[0051] C: mass concentration of adsorbed compound in the supernatant after reaching adsorption equilibrium (mg / L);

[0052] V: volume of adsorption solution (L);

[0053] W: mass of imprinted polymer (g).

[0054] Experimental Example 1: Investigating the Effect of Different Emulsifiers on Polymer Shape

[0055] Based on the preparation method in Example 2, different emulsifiers were used as dispersions (see Table 1) to obtain molecularly imprinted polymers. The adsorption amount of ginsenoside Rb1 was measured according to 2.1. The results are shown in Table 1:

[0056] Table 1

[0057]

[0058]

[0059] As shown in Table 1, the molecular imprinted polymers prepared by using docusate sodium (AOT), octylphenol polyoxyethylene ether (OP-10), and Triton X-100 as emulsifiers have strong adsorption capacity for ginsenoside Rb1. However, the molecular imprinted polymers prepared by using Span 80 as an emulsifier have weaker adsorption capacity for ginsenoside Rb1 than the other three.

[0060] Experimental Example 2 Investigating the effects of different functional monomer types and proportions used in the dispersed phase preparation step on the properties of molecularly imprinted polymers

[0061] Based on the preparation method in Example 2, different functional monomer types and ratios (see Table 2) were used to obtain different molecularly imprinted polymers, and their adsorption amounts for ginsenoside Rb1 were measured. The results are shown in Table 2:

[0062] Table 2

[0063] Serial number Functional monomer and dosage (molar amount) Polymer adsorption 1 Template molecule / acrylic acid (1:5.5) 49.91mg / g 2 Template molecule / allylamine (1:5.5) 59.07mg / g 3 Template molecule / methacrylic acid (1:5.5) 41.03mg / g 4 Template molecule / allylamine (1:3.5) 16.98mg / g 5 Template molecule / allylamine (1:4.5) 50.24mg / g 6 Template molecule / allylamine (1:6.5) 44.87mg / g 7 Template molecule / allylamine (1:7.5) 37.11mg / g

[0064] As shown in Table 2, when acrylic acid, allylamine and methacrylic acid are selected as hydrophilic functional monomers and the template molecule is used in combination with them at a molar ratio of 1:5.5, the prepared molecular imprinted polymer has a good adsorption capacity for ginsenoside Rb1. The adsorption capacity is the largest when the template molecule and allylamine are used in combination at a molar ratio of 1:5.5, which is 59.07 mg / g. When the template molecule and allylamine are used in combination at different molar ratios, the adsorption capacity of the prepared molecular imprinted polymer for ginsenoside Rb1 changes greatly. When the molar ratio of the template molecule to allylamine is 1:3.5, the adsorption capacity is significantly reduced to 16.98 mg / g. When the molar ratio of the template molecule to allylamine is 1:4.5 and 1:7.5, the adsorption capacity is slightly lower than that when the molar ratio is 1:5.5.

[0065] Experimental Example 3 Investigating the Effect of Using Different Crosslinking Agents in the Preparation of Dispersed Phase on Molecularly Imprinted Polymers

[0066] Based on the preparation method in Example 2, different cross-linking agents (see Table 3) were used to obtain different molecularly imprinted polymers, and their adsorption amounts for ginsenoside Rb1 were measured. The results are shown in Table 3:

[0067] Table 3

[0068] Crosslinking agent Polymer adsorption N,N'-Methylenebisacrylamide (MBA) 59.72mg / g Trimethoxypropyl trimethacrylate (TRIM) 43.89mg / g Divinylbenzene (DVB) 27.44mg / g

[0069] It can be seen from Table 3 that different molecular imprinting polymers prepared by using N,N'-methylenebisacrylamide and trimethoxypropyl trimethacrylate as cross-linking agents all have good adsorption capacity for ginsenoside Rb1; the molecular imprinting polymer prepared by divinylbenzene (DVB) has a slightly lower adsorption effect on ginsenoside Rb1 than the other two.

[0070] Experimental Example 4 Investigating the Effect of Using Different Initiators in the Polymerization Step on the Properties of Molecularly Imprinted Polymers

[0071] Based on the preparation method in Example 2, different initiators (see Table 4) were used to observe the reaction performance of different molecularly imprinted polymers. The results are shown in Table 4:

[0072] Table 4

[0073] Initiator Polymerization Potassium Persulfate Simple operation, quick response, stable process Ammonium Persulfate Simple operation, quick response, stable process

[0074] As shown in Table 4, different molecular imprinted polymers can be successfully prepared by using potassium persulfate and ammonium persulfate as initiators, and both are simple to operate and have rapid reactions.

[0075] Experimental Example 5 Investigating the Effect of Different Reaction Conditions in the Polymerization Step on the Properties of Molecularly Imprinted Polymers in the Preparation Method

[0076] Based on the preparation method in Example 2, different molecular imprinted polymers were prepared by changing the reaction conditions of the polymerization reaction, including reaction temperature, reaction time, and mechanical stirring speed (see Table 5), and their adsorption amounts for ginsenoside Rb1 were measured respectively. The results are shown in Table 5:

[0077] Table 5

[0078]

[0079] It can be seen from Table 5 that molecularly imprinted polymer microspheres can be prepared under the conditions of polymerization reaction temperature of 35-80°C and reaction time of 1-4h. The best adsorption effect on ginsenoside Rb1 was achieved when the reaction temperature was 65°C and the reaction time was 2h.

[0080] Example 3 Testing the adsorption performance of the molecularly imprinted polymer obtained in Example 2 on various natural saponins:

[0081] The adsorption performance test of ginsenoside Rb1 was carried out according to the method described in 2.1, except that the test molecule used a substitute molecule (natural saponin compound molecule) to replace ginsenoside Rb1. The obtained data are shown in Table 6.

[0082] Table 6

[0083] serial number Chemical name CAS Number Adsorption capacity (mg / g) 1 Panax japonicus saponin IV 51415-02-2 56.34 2 Kochia scoparia saponin II 95851-41-5 54.23 3 Platycodon saponin D 58479-68-8 48.09 4 Saikosaponin A 20736-09-8 45.67 5 Araliaside A 7518-22-1 54.11 6 Araliaside B 156980-31-3 51.45 7 Araliaside C 55446-15-6 49.88 8 Aescin 6805-41-0 53.32 9 Sanguisorba officinalis saponin Ⅱ 35286-59-0 52.66 10 Sanguisorba officinalis saponin I 35286-58-9 50.24 11 Kochia scoparia saponin IC 96990-18-0 48.12

[0084] It can be seen from Table 6 that the molecular imprinting polymer prepared in Example 2 has good adsorption performance for the natural saponin compound molecules of Rhizoma Panacissomatae saponins IV, Kochia scoparia saponins II, Platycodon saponins D, Bupleurosaponin A, Araliasin A, Araliasin B, Araliasin C, Aescin, Sanguisorbaside II, Sanguisorbaside I, and Kochia scoparia saponins IC.

[0085] Example 4 Application of the molecularly imprinted polymer obtained in Test Example 2

[0086] In order to verify the separation performance and application potential of the molecularly imprinted polymer microspheres, the molecularly imprinted polymer microspheres were used as an adsorbent material for internal phase extraction to enrich and separate ginsenoside Rb1 from ginseng medicinal material extract.

[0087] The specific experiments are as follows:

[0088] (1) Preparation of ginseng extract: Weigh 0.5 g of ginseng root (crushed to pass through a 20-mesh sieve), add 80 mL of 60% ethanol solution, and extract under ultrasonic reflux for 0.5 h. Separate the supernatant after centrifugation. Repeat the extraction residue three times, combine the supernatants, and concentrate them by rotary evaporation to obtain ginseng extract (rice: extract = 5:1, W / W), which is sealed and kept at low temperature for later use.

[0089] (2) Adsorption experiment: First, 200 mg of molecularly imprinted polymer was loaded into a solid phase extraction column and activated with 5 mL of methanol. Then, 5 mg / mL of ginseng extract loading solution was prepared with methanol, and 3 mL of loading solution was loaded; 6 mL of methanol was used for elution; and ethanol-acetic acid (90:10, v / v) was used for elution.

[0090] (3) Result analysis: The collected solution was tested by HPLC according to the detection method of ginsenoside Rb1 in ginseng medicinal materials in the Chinese Pharmacopoeia 2015 edition P8-9. The concentration of ginsenoside Rb1 in the solution before and after adsorption was calculated, and the recovery rate was 79.5%.

[0091] The above is only an implementation method of the invention, and does not limit the scope of patent protection. Those skilled in the art can make non-substantial changes or substitutions based on the invention, which still fall within the scope of patent protection.

Claims

1. A template molecule, characterized in that The structural formula is as follows:

2. A molecularly imprinted polymer prepared from the template molecule according to claim 1, characterized in that: Preparation method thereof The following operations are included: Prepare dispersed phase: mix hydrophilic functional monomer, crosslinking agent, water and template molecule to prepare solution A; Prepare the continuous phase: mix the emulsifier with n-hexane under an inert gas atmosphere to form a continuous phase as solution B; Preparation of inverse dispersion system: Mix solution A and solution B under an inert gas atmosphere to obtain a white emulsion; Polymerization reaction: Mix the white latex with the initiator to obtain a polymer microsphere mixture; Post-treatment: Mix the polymer microsphere mixture with methanol, filter out the precipitate, wash the precipitate to neutrality after eluting the template molecules, and then dry it to constant weight to obtain molecularly imprinted polymer microspheres.

3. The molecularly imprinted polymer according to claim 2, characterized in that In preparing the dispersed phase, the hydrophilic functional monomer is one of acrylic acid, allylamine and methacrylic acid.

4. The molecularly imprinted polymer according to claim 2, characterized in that In preparing the dispersed phase, the crosslinking agent is at least one of N,N'-methylenebisacrylamide, trimethoxypropyl trimethacrylate and divinylbenzene.

5. The molecularly imprinted polymer according to claim 2, characterized in that In preparing the dispersed phase, the molar ratio of the hydrophilic functional monomer to the template molecule is 1:4.5-7.

5.

6. The molecularly imprinted polymer according to claim 2, characterized in that In the preparation of the continuous phase, the emulsifier is at least one of docusate sodium, octylphenol polyoxyethylene ether, and Triton X-100.

7. The molecularly imprinted polymer according to claim 2, characterized in that In the polymerization reaction, the initiator is one of potassium persulfate and ammonium persulfate.

8. The molecularly imprinted polymer according to claim 2, characterized in that During the polymerization reaction, the polymerization temperature is 35 to 80°C.

9. The molecularly imprinted polymer according to claim 2, characterized in that During the polymerization reaction, the polymerization reaction time is 1 to 4 hours, and stirring is continued during the polymerization reaction.

10. Use of the molecularly imprinted polymer according to any one of claims 2 to 9 in separating natural saponin compounds, characterized in that: The natural saponin compound is one of ginsenoside Rb1, ginsenoside IV, kochia scoparia saponin II, platycodon saponin D, bupleurosaponin A, aralia glycoside A, aralia glycoside B, aralia glycoside C, aescin, sanguisorbaside II, sanguisorbaside I, and kochia scoparia saponin IC.

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