CN111518156B

CN111518156B - One-step preparation method of astragaloside

Info

Publication number: CN111518156B
Application number: CN202010472785.8A
Authority: CN
Inventors: 青琳森; 丁立生; 杨雪锋; 彭树林; 梁健
Original assignee: Chengdu Institute of Biology of CAS
Current assignee: Chengdu Institute of Biology of CAS
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2021-07-27
Anticipated expiration: 2040-05-29
Also published as: CN111518156A

Abstract

The invention belongs to the field of compound synthesis, and particularly relates to a one-step preparation method of astragaloside. The specific technical scheme is as follows: adding a halogenated salt and water into a pH buffer system at room temperature; stirring until the mixture is completely dissolved, adding astragaloside IV and tetrahydrofuran, cooling to 0-5 ℃ in an ice water bath, then adding TEMPO, and then dropwise adding a hypochlorite aqueous solution; after the reaction is completed, preserving the temperature for 30min, decompressing, concentrating and filtering to obtain the astragaloside. The invention provides a preparation method of a novel astragaloside acid derivative, which takes astragaloside as a raw material, can simply and quickly obtain astragaloside salt by one step, has simple operation, complete reaction and cheap and easily obtained raw materials, and obtains a pure product.

Description

One-step preparation method of astragaloside

Technical Field

The invention belongs to the field of compound synthesis, and particularly relates to a one-step preparation method of astragaloside.

Background

Astragaloside IV is one of the main active components of radix astragali, and has various pharmacological effects of improving cardiopulmonary function, enhancing immunity, etc. The astragaloside is C on glucose group in astragaloside IV molecule₆The hydroxymethyl group is directionally oxidized into a carboxyl group to obtain a product; compared with astragaloside IV, it has better drug property. In order to further develop the astragaloside IV into water-soluble formulations such as injection and the like, the astragaloside IV also needs to be prepared into salts, especially alkali metal salts, of the astragaloside IV so as to further improve the water-solubility.

At present, the research on the preparation method of the water-soluble derivatives of the astragaloside acid in the industry is less, and the existing feasible research is the prior research of the inventor: the patent of astragaloside IV derivative, its preparation method and application includes the following authorization notice numbers: CN 106632572B. It describes a process for the preparation of astragaloside derivatives. However, the synthetic method has a long route and needs to be subjected to three steps of oxidation, dissociation and salification in sequence. Meanwhile, the method also has the defects of large solvent dosage, incomplete reaction of raw materials (astragalus nucleotide) and the like. Therefore, the method for preparing the astragalus nucleotide salt has the advantages of short reaction route and complete reaction of raw materials, and has important practical significance.

Disclosure of Invention

The invention aims to provide a preparation method of astragalus nucleotide salt, which has short reaction route and complete reaction of raw materials.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: a method for preparing astragaloside comprises the following steps: in a pH buffer system, tetrahydrofuran/water is used as a solvent, astragaloside is used as a raw material, and the reaction is carried out in the presence of halide salt, TEMPO and hypochlorite to obtain the compound.

Preferably, the pH buffer system is a bicarbonate/carbonate buffer system or a hydrogen phosphate/phosphate buffer system, and the metal ions in the pH buffer system are the same as those in the astragaloside to be prepared.

Preferably, the pH buffering system is a bicarbonate/carbonate buffering system.

Preferably, the solvent is one of tetrahydrofuran aqueous solution, methyltetrahydrofuran aqueous solution, N-dimethylformamide aqueous solution and dimethylacetamide aqueous solution.

Preferably, the halide salt and the hypochlorite are both metal salts, and the metal ion is the same as the metal ion of the astragaloside salt to be prepared.

Preferably, the method comprises the following steps:

adding a halide salt and water to a bicarbonate/carbonate buffer system at room temperature; stirring until the mixture is completely dissolved, adding astragaloside IV and tetrahydrofuran, cooling to 0-5 ℃ in an ice water bath, then adding TEMPO, and then dropwise adding a hypochlorite aqueous solution; after the reaction is completed, preserving the temperature for 30min, decompressing, concentrating and filtering to obtain the crude product of the astragalus nucleotide salt.

Preferably, the crude astragaloside hydrochloride is washed by using formate aqueous solution or acetate aqueous solution and methanol respectively to obtain the pure astragaloside hydrochloride.

Preferably, the formate and the acetate are metal salts, and the metal ions are the same as those of the halide salt.

Preferably, the halide salt is sodium bromide.

Preferably, the hypochlorite is sodium hypochlorite.

Preferably, the formate is sodium formate, or the acetate is sodium acetate.

The invention has the following beneficial effects:

the invention provides a novel astragalus nucleotide derivative: alkali metal salt of astragaloside, especially sodium astragaloside is provided. And provides a specific preparation method, the astragaloside can be simply and rapidly obtained by only one step, the operation is simple, and the raw materials are cheap and easy to obtain. In the reaction, all the used salts and alkalis are adjusted to metal ions which are consistent with the required alkali metal salt, and finally, the required metal ions only exist in the reaction system, so that the pure astragalus nucleotide alkali metal salt is obtained.

The reaction system adopts a pH buffer system, on one hand, the steps of acid regulation and salt formation are omitted, side reactions caused by adding strong acid and strong base are avoided, and the product purity is further improved. On the other hand, the problem that the pH of the reaction system is continuously reduced along with the reaction and the astragaloside cannot be completely reacted even if excessive hypochlorite is added is effectively solved. The reasons for this problem are: in the initial stage of the reaction, the dropwise added sodium hypochlorite solution allows the oxidation reaction to proceed smoothly in the presence of its own alkalinity and a small amount of sodium hydroxide (in order to maintain the stability of sodium hypochlorite, a small amount of sodium hydroxide is usually left in a commercially available sodium hypochlorite aqueous solution to maintain a high pH). With the progress of the oxidation reaction, the generated carboxyl can generate neutralization reaction with sodium hydroxide and sodium hypochlorite, so that the pH value of a reaction system is reduced, and the newly dripped sodium hypochlorite is mainly decomposed to generate neutral sodium chloride and oxygen in a low pH environment, so that the oxidation reaction cannot be continued. The buffer system adopted by the invention can automatically adjust the pH value, and ensures that the reaction system is in a proper pH range in the whole reaction process. Meanwhile, the buffer system can control the reaction to be carried out under the alkalescent condition all the time, so as to prevent the hypochlorite from decomposing too fast. In addition, the application of the buffer system ensures that the reaction is complete, and the amount of the added reactants is controllable, so that the residue of inorganic salt in the product can be effectively reduced; the washing of the formate or acetate aqueous solution after the reaction can further remove inorganic salt generated by the reaction, thereby ensuring the purity of the product.

The solvent used in the invention can be any one of a tetrahydrofuran/water system, a methyltetrahydrofuran/water system, an N, N-dimethylformamide/water system and a dimethylacetamide/water system, and compared with a dioxane/water system used in the prior art, the solvent has better solubility for the raw material of astragaloside, can effectively reduce the dosage of the solvent, saves the cost and is beneficial to the amplification reaction in industrial production.

Detailed Description

The invention provides a new astragaloside acid derivative, in particular to an astragaloside acid alkali metal salt, such as astragaloside sodium. The structural formula of the sodium astragaloside is as follows: NaC₄₁H₆₅O₁₅。

The invention also provides a preparation method of the astragalus nucleotide alkali metal salt. The method specifically comprises the following steps:

and (3) adding 0.01-0.2 equivalent of halide salt and water into a pH buffer system at room temperature. The amount of the added water is 5-50 mL/g, preferably 25-35 mL/g, based on the added mass of the astragaloside. Stirring to dissolve completely, and adding astragaloside IV and solvent. The solvent is one of tetrahydrofuran, methyltetrahydrofuran, N-dimethylformamide and dimethylacetamide, and tetrahydrofuran is preferred. The dosage of the tetrahydrofuran is 5-50 mL/g, preferably 25-35 mL/g, based on the added mass of the astragaloside. Then cooling to 0-5 ℃ in an ice water bath, adding 0.01-0.2 equivalent of 2,2,6, 6-tetramethylpiperidine oxide (TEMPO), and dropwise adding a hypochlorite aqueous solution until the reaction is complete; in the hypochlorite aqueous solution, the content of available chlorine is 3-13%. The bicarbonate, carbonate, hypochlorite and halide are all metal salts, and the metal ions thereof are the same. After the reaction is completed, the temperature is kept for 30 min. And then, concentrating the reaction solution under reduced pressure at the water bath temperature of less than or equal to 45 ℃, stirring at room temperature for 12-16 h, and filtering to obtain a crude product of the astragalus membranaceus nucleotide alkali metal salt.

The pH buffer system is a buffer system with the pH of 8-10, does not participate in the reaction, and has the same metal ions as those of the astragaloside to be prepared. For example, a bicarbonate/carbonate buffer system, or a hydrogen phosphate/phosphate buffer system, etc. Preferably a bicarbonate/carbonate buffer system.

For example, in the preparation of sodium astragaloside, the buffer system is sodium bicarbonate/carbonate, the halide salt is sodium bromide, and the hypochlorite is sodium hypochlorite. Similarly, when preparing the potassium astragaloside, the buffer system is potassium carbonate/potassium bicarbonate solution, the halide salt can be potassium bromide, the hypochlorite is potassium hypochlorite, and the like.

The preferable scheme is as follows: refining and purifying the crude astragalus membranaceus alkali metal salt to obtain a pure astragalus membranaceus alkali metal salt product. The specific method comprises the following steps: adding 5-25% of formate aqueous solution or acetate aqueous solution into the crude astragalus nucleotide alkali metal salt, preferably 8-12% of formate aqueous solution or acetate aqueous solution. The mixture is stirred and washed for more than 24 hours at room temperature. The formate or acetate is a metal salt, and the metal ion is the same as that of the halide salt. And (4) filtering under reduced pressure after washing, washing with a formate or acetate aqueous solution, and filtering under reduced pressure once to obtain a filter cake. The filter cake was washed with methanol with stirring over 24 h. And (3) carrying out reduced pressure filtration again after washing, washing with methanol, carrying out reduced pressure filtration once, and drying the filter cake obtained again at 35-40 ℃ under reduced pressure until the weight is constant to obtain the required pure product of the astragalus nucleotide alkali metal salt.

The present invention will be further explained with reference to specific examples.

Example (b): preparation of sodium astragaloside

1. 4.5g of sodium bicarbonate, 13.5g of anhydrous sodium carbonate, 5.0g of sodium bromide and 1500mL of water were added to a 5L reaction flask at room temperature and stirred until completely dissolved. Subsequently, 50.0g of astragaloside IV and 1500mL of tetrahydrofuran were added, the temperature was reduced to 0 ℃ in an ice-water bath, and 2.0g of TEMPO was added. Controlling the reaction temperature within the range of 0-5 ℃, dropwise adding a commercially available sodium hypochlorite aqueous solution until the TLC detection reaction is complete, and then preserving the temperature for 30 min. And then concentrating the reaction solution to 1500 +/-80 g under reduced pressure at the water bath temperature of less than or equal to 45 ℃, stirring for 12-16 h at room temperature, and filtering to obtain a crude product of the sodium astragaloside IV.

2. Transferring the obtained crude product into a 1000mL four-mouth bottle, adding 500g of 10% sodium formate aqueous solution, stirring and washing at room temperature for 24h, filtering under reduced pressure, stirring and washing the obtained filter cake for 24h at room temperature by using 500g of 10% sodium formate aqueous solution, and filtering under reduced pressure again.

And transferring the obtained filter cake into a 1000mL four-mouth bottle, adding 500mL of methanol, stirring and washing at room temperature for 24h, filtering under reduced pressure to obtain a filter cake, stirring and washing the filter cake with 500mL of methanol for 24h, filtering under reduced pressure to obtain a filter cake, and drying the filter cake under reduced pressure at 35-40 ℃ to constant weight to obtain 33.2g of the pure astragaloside sodium product with the yield of 63.5%.

The preparation is repeated for three times according to the method, the pure product of the sodium astragaloside is successfully prepared and obtained, and the amount obtained by each preparation is 33.2g, 32.5g and 32.2g respectively.

The sodium astragaloside IV is white powder, and has HR-ESI-MS excimer peak M/z [ M-H ]]^-797.4693. The nuclear magnetic resonance carbon spectrum is as follows: 29.4(C-1),30.8(C-2),89.2(C-3),41.5(C-4),51.8(C-5),80.4(C-6),34.7(C-7),44.8(C-8),20.6(C-9),26.5(C-10),25.4(C-11),33.0(C-12),44.7(C-13),45.7(C-14),46.4(C-15),73.5(C-16),57.3(C-17),21.3(C-18),32.1(C-19),87.5(C-20),26.0(C-21),34.3(C-22),25.7(C-23),81.1(C-24),71.9(C-25),27.9(C-26),29.1(C-27),19.5 (C-27), 29.5 (C-27), 16.0(C-30),105.7(C-1'),73.8(C-2'),76.7(C-3'),71(C-4'),65.1(C-5'),103.2(C-1 "), 73.6 (C-2"), 76.3(C-3 "), 72.1 (C-4"), 76.0(C-5 "), 175.5 (C-6").

Claims

1. A method for preparing astragaloside is characterized in that: the method comprises the following steps: in a pH buffer system, dissolving astragaloside IV in a solvent, and reacting in the presence of a halide salt, TEMPO and hypochlorite to prepare the astragaloside IV; the solvent is one of tetrahydrofuran aqueous solution, methyl tetrahydrofuran aqueous solution and dimethylacetamide aqueous solution.

2. The method for preparing astragaloside according to claim 1, characterized in that: the pH buffer system is a bicarbonate/carbonate buffer system or a hydrogen phosphate/phosphate buffer system, and the metal ions in the pH buffer system are the same as those of the astragaloside to be prepared.

3. The method for preparing astragaloside according to claim 1, characterized in that: the halide salt and the hypochlorite are both metal salts, and the metal ions are the same as those of the astragaloside to be prepared.

4. The method for preparing astragaloside according to claim 1, characterized in that: the method comprises the following steps:

adding a halide salt and water to a bicarbonate/carbonate buffer system at room temperature; stirring until the mixture is completely dissolved, adding astragaloside and a solvent, cooling to 0-5 ℃ in an ice water bath, then adding TEMPO, and then dropwise adding a hypochlorite aqueous solution; after the reaction is completed, preserving the temperature for 30min, decompressing, concentrating and filtering to obtain the crude product of the astragalus nucleotide salt.

5. The method for preparing astragaloside according to claim 4, wherein: and washing the crude astragalus membranaceus nucleotide salt product by using formate aqueous solution or acetate aqueous solution and methanol respectively to obtain a pure astragalus membranaceus nucleotide salt product.

6. The method for preparing astragaloside according to claim 5, wherein: the formate and the acetate are metal salts, and the metal ions are the same as those of the halide salt.

7. The method for preparing astragaloside according to any one of claims 4 to 6, characterized in that: the halide salt is sodium bromide.

8. The method for preparing astragaloside according to claim 7, characterized in that: the hypochlorite is sodium hypochlorite.

9. The method for preparing astragaloside according to claim 8, wherein: the formate is sodium formate, or the acetate is sodium acetate.