Preparation method of high-purity isoglycyrrhizic acid

Abstract

The invention belongs to the technical field of biological medicines, and relates to a preparation method of high-purity isoglycyrrhizic acid. The preparation method comprises the following steps: (1) taking monoammonium isoglycyrrhizinate or monopotassium isoglycyrrhizinate as a raw material, reacting with acetyl chloride and methanol to prepare methyl isoglycyrrhizinate, carrying out suction filtration on a reaction solution, and collecting a filter cake to obtain a methyl isoglycyrrhizinate crude product; and (2) sequentially pulping the methyl isoglycyrrhizinate crude product with water and recrystallizing with an organic solvent to obtain the high-purity methyl isoglycyrrhizinate. And (3) hydrolyzing the high-purity methyl isoglycyrrhizinate, cooling, adding glacial acetic acid into the reaction liquid, stirring, dropwise adding diluted hydrochloric acid into the reaction liquid until the pH value is 1-3, carrying out suction filtration, stirring, and drying a filter cake to obtain the high-purity isoglycyrrhizinic acid. The high-purity isoglycyrrhizic acid can be obtained by controlling the reaction conditions of the esterification reaction, screening the recrystallization solvent and combining with a hydrolysis reaction post-treatment method. The obtained product has the advantages of high purity, simple post-treatment operation and high yield, and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biological medicine, and relates to a preparation method of a medical intermediate, in particular to a preparation method of high-purity glycyrrhizic acid. BACKGROUND

[0002] Glycyrrhizic acid is the main active component in licorice and is often used in the treatment of various liver diseases. Natural glycyrrhizic acid is mainly cis-glycyrrhizic acid, and a small amount of trans-glycyrrhizic acid (18-α-glycyrrhizic acid, 18-α-GL) also exists in licorice. Glycyrrhizic acid preparations, from the initial mixed extract of licorice to the first generation of glycyrrhizic acid preparation, such as Mengneng and the second generation of preparation, Qianglingning, are mainly composed of glycyrrhizic acid monosodium salt. In 1994, the third generation of glycyrrhizic acid preparation was developed, and its representative drug is Ganlixin, which is a mixed preparation of α body and β body. The drug has the effects of anti-inflammatory, enzyme reduction, jaundice reduction, liver cell membrane protection and liver function improvement, and has been widely used in the treatment of various hepatitis. Recently, glycyrrhizic acid has a fourth generation preparation, magnesium isoglycyrrhizate, which is a magnesium salt of 18α-stereoisomer of glycyrrhizic acid. Compared with the previous glycyrrhizic acid preparations, magnesium isoglycyrrhizate has the advantages of prominent pharmacokinetic advantages, rapid onset speed, high safety and the like. Therefore, the drug has become a main drug for treating liver diseases. 18-β-GL and 18-α-GL have the same molecular formula, only the difference in the configuration of 18H, but their properties are completely different.

[0003] The production process of magnesium isoglycyrrhizate includes four steps of isomerization, esterification, hydrolysis and salt formation. There are problems of low conversion rate, high waste liquid and high production cost in the process.

[0004] At present, the synthesis method of magnesium isoglycyrrhizate mainly adopts the synthesis route disclosed in CN1169826C.

[0005]

[0006]

[0007] In order to obtain magnesium isoglycyrrhizate meeting the quality standard, high-purity isoglycyrrhizic acid needs to be obtained first. However, in the above synthesis method, two problems need to be solved to obtain high-purity isoglycyrrhizic acid. On the one hand, a small amount of unreacted glycyrrhizic acid exists in the product of the first step, and the cis-glycyrrhizic acid methyl ester generated by esterification reaction is difficult to completely remove; at the same time, the impurity A introduced from the raw material is very similar in structure to glycyrrhizic acid, and the corresponding methyl ester generated by esterification reaction after isomerization in the first step is difficult to remove. On the other hand, the concentration process of the extraction liquid after the third step of hydrolysis reaction and the recrystallization process of glacial acetic acid are prone to deterioration and produce impurities, which affect the final product.

[0008]

[0009] For the purification of methyl isoglycyrrhizinate, CN1381463A and CN102584928A both adopt the method of methanol washing. Through repeated experiments, it is confirmed that the effect of using methanol to wash methyl isoglycyrrhizinate is not ideal, and the purity of the final product prepared is not high. At the same time, CN107488207A discloses a purification method of methyl isoglycyrrhizinate, and confirms that it can control the amount of impurity A to be below 0.3%. The method needs to go through three purification processes, and the process is complex. At the same time, the first step needs to use DMF / methanol / water mixed solvent, which is not conducive to the recycling of solvents in subsequent industrial production. In addition, in this method, the amount of solvent has an important influence on the purification effect. When different amounts of solvents are selected for purification according to the method described in the patent, the content of impurity A is reduced to a certain extent, but the content of impurity A is much higher than 0.3%, and the yield is particularly low. CN116693594A avoids the generation of impurities in the concentration and recrystallization process by directly forming a salt with the calculated amount of basic magnesium carbonate. However, it is found through repeated experiments that the pH value of the water phase in the extraction process seriously affects the amount of isoglycyrrhizic acid in the extract, so that the proportion of salting is difficult to confirm, and the yield also fluctuates greatly.

[0010] In addition, magnesium isoglycyrrhizinate has not been included in the Pharmacopoeia of various countries, and the disclosed quality standards are relatively few. In order to improve the quality of magnesium isoglycyrrhizinate, it is necessary to develop a high-efficiency, environmentally friendly and suitable industrial production method to improve the purity of the intermediate isoglycyrrhizic acid, and then improve the quality of magnesium isoglycyrrhizinate. SUMMARY

[0011] In order to solve the problems of the prior art, the purpose of the present application is to provide a preparation method of high-purity isoglycyrrhizic acid. The preparation method of isoglycyrrhizic acid provided by the present application is simple in operation, high in yield, high in purity of the obtained product, and suitable for industrial production.

[0012] The purpose of the present application is achieved as follows:

[0013] A preparation method of high-purity isoglycyrrhizic acid, comprising the following steps:

[0014] (1) taking monoammonium isoglycyrrhizinate or monopotassium isoglycyrrhizinate as raw material, reacting with acetyl chloride and methanol to prepare methyl isoglycyrrhizinate, and then filtering the reaction solution to collect the filter cake to obtain crude methyl isoglycyrrhizinate.

[0015] (2) The crude methyl isoglycyrrhizinate is sequentially subjected to water beating and organic solvent recrystallization to obtain high-purity methyl isoglycyrrhizinate.

[0016] (4) high-purity glycyrrhizinic acid is obtained by hydrolysis of high-purity methyl glycyrrhizinate, cooling, adding glacial acetic acid to the reaction solution, stirring, adding dilute hydrochloric acid dropwise to the solution until pH = 1-3, filtering, stirring, and drying the filter cake.

[0017] In step (1), the molar ratio of the monoammonium glycyrrhizinate or the monopotassium glycyrrhizinate to acetyl chloride is 1:3-10, preferably 1:6-7;

[0018] In step (1), the weight-to-volume ratio of the monoammonium glycyrrhizinate or the monopotassium glycyrrhizinate to methanol is 1:3-10, preferably 1:7-10;

[0019] In step (1), the reaction temperature is 10-50°C, preferably 20-25°C;

[0020] In step (2), the weight-to-volume ratio of the crude methyl glycyrrhizinate to water is 1:3-10, preferably 1:7-10; the beating and stirring temperature is 0-30°C, preferably 20-25°C; and the stirring time is 1-2 h;

[0021] In step (2), the weight-to-volume ratio of the crude methyl glycyrrhizinate after beating and filtration to the organic solvent is 1:3-20, preferably 1:4-6; the stirring temperature is 30-120°C, preferably 70-90°C; the stirring time is 0.5-10 h, preferably 1-3 h; and the temperature is lowered to 10-30°C;

[0022] In step (2), the organic solvent is methanol, ethanol, dimethyl sulfoxide, dimethyl formamide, tetrahydrofuran, or glacial acetic acid, preferably glacial acetic acid;

[0023] In step (3), the weight-to-volume ratio of the high-purity methyl glycyrrhizinate to water is 1:3-20, preferably 1:3-5; the mass ratio of the high-purity methyl glycyrrhizinate to sodium hydroxide is 1:0.2-0.4; the hydrolysis temperature is 10-100°C, preferably 70-90°C; and the hydrolysis time is 1-5 h, preferably 1-3 h;

[0024] In step (3), the weight-to-volume ratio of the high-purity methyl glycyrrhizinate to glacial acetic acid is 1:5-20, preferably 1:8-12; the stirring time is 3-4 h; and the stirring temperature is 0°C.

[0025] Further, the preparation method of glycyrrhizinic acid according to the present application comprises the following steps:

[0026] (1) Add the mono-ammonium or mono-potassium salt of glycyrrhizinic acid into a reaction bottle, add 7-10 times the amount of methanol (weight / volume), control the temperature at 0°C, add 6-7 times the molar amount of acetyl chloride dropwise into the reaction bottle, raise the temperature to 20-25°C and react overnight, filter, collect the filter cake, and obtain the crude glycyrrhizinic acid methyl ester.

[0027] (2) Add the crude glycyrrhizinic acid methyl ester obtained in step 1 into 7-10 times the amount of purified water, stir at 20-25°C, filter, dry the filter cake, add it into 4-6 times the amount of glacial acetic acid, stir at 70-90°C for 1-3 hours, lower the temperature to 10-30°C, crystallize, filter, and collect the filter cake.

[0028] (3) Add the filter cake obtained in step 2 into 3-5 times the amount of purified water, react with 0.2-0.4 times the amount of sodium hydroxide at 70-90°C for 1-3 hours, after the reaction is complete, lower the temperature to 0°C, add 8-12 times the amount of glacial acetic acid into the reaction solution, stir for 1-2 hours, add dilute hydrochloric acid with pH = 1-2 dropwise into the reaction solution until the pH = 1-3, continue to stir the reaction solution for 3-4 hours, filter, and dry the filter cake to obtain high-purity glycyrrhizinic acid.

[0029] Advantages of the present application:

[0030] The present application can obtain high-purity glycyrrhizinic acid by controlling the reaction conditions of esterification, screening the recrystallization solvent, and combining the post-treatment method of hydrolysis reaction. The product obtained by the present application has high purity, simple post-treatment operation, high yield, and is suitable for industrial production. DETAILED DESCRIPTION

[0031] Example 1: Synthesis of crude glycyrrhizinic acid methyl ester

[0032] At room temperature, add 20 g of mono-potassium salt of glycyrrhizinic acid (0.0232 mol) into a 500 ml reaction bottle, add 200 ml of anhydrous methanol, stir, lower the temperature to 0°C, and add acetyl chloride (12 g, 0.154 mol) dropwise. After 30 minutes, raise the temperature to room temperature, stir overnight, filter, wash the filter cake with methanol, and dry to obtain 13.4 g of crude product with a HPLC purity of 90.1% and an impurity A content of 1.914%.

[0033] Example 2: Refinement of glycyrrhizinic acid methyl ester

[0034] Add the crude glycyrrhizinic acid methyl ester (13 g, 0.148 mol) into a 250 ml reaction bottle, add 130 ml of purified water, and beat at room temperature for 1 hour. Filter, dry the filter cake, and then recrystallize it with 50 ml of glacial acetic acid at 80°C for 2 hours. Lower the temperature to 20°C to obtain 6.9 g of glycyrrhizinic acid methyl ester with a HPLC purity of 98.64% and an impurity A content of 0.74%.

[0035] According to the above method, different solvents, the amount of solvent and its reaction temperature are changed to prepare methyl isoglycyrrhizinate, and the influence of different conditions on the purity of methyl isoglycyrrhizinate, the content of impurity A and the yield is investigated, and the results are shown in Table 1 (wherein the feeding ratio is the volume ratio of the organic solvent to the mass of the methyl isoglycyrrhizinate crude product after pulping and filtration) :

[0036] Table 1 Influence of solvent type and recrystallization temperature on the purity of the intermediate

[0037]

[0038]

[0039] The results show that when methanol, ethanol, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran and glacial acetic acid are used as the solvent for recrystallization, the amount of solvent is 4-6 times of the methyl isoglycyrrhizinate crude product after pulping and filtration, and the recrystallization temperature is 60-100℃, the purity of methyl isoglycyrrhizinate is more than 95% and the content of impurity A is less than 1.75%. When glacial acetic acid is used as the solvent for recrystallization, the amount of solvent is 5-6 times of the methyl isoglycyrrhizinate crude product after pulping and filtration, and the recrystallization temperature is 60-80℃, the purity of methyl isoglycyrrhizinate can reach more than 98% and the content of impurity A is less than 1%. Therefore, glacial acetic acid is preferred as the recrystallization solvent, and the amount of glacial acetic acid is 5-6 times of the methyl isoglycyrrhizinate crude product after pulping and filtration, and the recrystallization temperature is 60-100℃.

[0040] Example 3: Preparation of isoglycyrrhizic acid

[0041] The high-purity methyl isoglycyrrhizinate (5g, 0.0057mol) of Example 2 is put into a 50ml reaction bottle, 15ml of purified water and 1.75g of NaOH are added, and the reaction is heated to 80℃ for 2h. The temperature is lowered to 0℃, 50ml of glacial acetic acid is added to the reaction solution, stirred for 1h, the pH of the reaction solution is adjusted to about 2 with dilute hydrochloric acid, the reaction solution is stirred at 0℃ for 3-4h, and then filtered and dried to obtain 3.2g of isoglycyrrhizic acid with a purity of 99.2% by HPLC and a content of impurity A of 0.17%.

[0042] The present application innovatively develops an "acid precipitation-in-situ purification" process to solve the technical problems of degradation of impurities in the extraction liquid concentration and recrystallization in the post-processing of the hydrolysis reaction. Thus, the post-processing operation of the process is simplified, and the generation of impurities is avoided.

[0043] According to the above method, the amount of water and glacial acetic acid, pH value are changed, and the hydrolysis reaction and post-processing process parameters are systematically investigated, and the influence of different conditions on the purity of isoglycyrrhizic acid, impurity A and yield is investigated. The results are shown in Table 2.

[0044] Table 2 Effect of dissolution multiple and system pH on yield and purity of target product

[0045]

[0046]

[0047] The results show that when the multiple of alkali is 0.3-0.4 times and the reaction temperature is 70-80℃, the hydrolysis reaction is complete. When the amount of purified water is 3 times of the high-purity glycyrrhizinic acid methyl ester, the amount of glacial acetic acid is 10 times of the high-purity glycyrrhizinic acid methyl ester, and the pH value is 1-3, the purity of the obtained glycyrrhizinic acid is more than 99%, the content of impurity A is less than 0.2%, and the yield is more than 40%. When the pH value is 1-2, the purity of the glycyrrhizinic acid is more than 99%, the content of impurity A is less than 0.2%, and the yield is more than 60%.

[0048] The preferred embodiments of the present application have been described above with the purpose of only illustrating the present application but not limiting the present application. The present application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing high purity Isoglycyrrhizinate, characterized in that, The method comprises the following steps:

1. Using mono-ammonium glycyrrhizinate or mono-potassium glycyrrhizinate as raw material, reacting with acetyl chloride and methanol to prepare methyl glycyrrhizinate, extracting the reaction solution, collecting the filter cake to obtain methyl glycyrrhizinate crude product; 2. The methyl glycyrrhizinate crude product is sequentially subjected to water beating, organic solvent recrystallization to obtain high-purity methyl glycyrrhizinate; 3. The high-purity methyl glycyrrhizinate is subjected to hydrolysis, cooling, adding glacial acetic acid to the reaction solution, stirring, and adding dilute hydrochloric acid dropwise to the solution until the pH value is 1-3, extracting, stirring, drying the filter cake to obtain high-purity glycyrrhizic acid.

2. The process for the preparation of high purity Isoglycyrrhizinate as claimed in claim 1 wherein, In the step (1), the molar ratio of mono-ammonium glycyrrhizinate or mono-potassium glycyrrhizinate to acetyl chloride is 1:3-10, preferably 1:6-7; the weight-volume ratio of mono-ammonium glycyrrhizinate or mono-potassium glycyrrhizinate to methanol is 1:3-10, preferably 1:7-10.

3. The process for the preparation of high purity Isoglycyrrhizinate as claimed in claim 1 or 2, wherein, In the step (1), the reaction temperature is 10-50℃, preferably 20-25℃.

4. The process for the preparation of high purity Isoglycyrrhizinate as claimed in any one of claims 1 to 3, wherein, In the step (2), the weight-volume ratio of the methyl glycyrrhizinate crude product to water is 1:3-10, preferably 1:7-10; the beating stirring temperature is 0-30℃, preferably 20-25℃; the stirring time is 1-2h.

5. The process for the preparation of high purity Isoglycyrrhizinate as claimed in any one of claims 1 to 4, wherein, In the step (2), the weight-volume ratio of the methyl glycyrrhizinate crude product after beating filtration to the organic solvent is 1:3-20, preferably 1:4-6.

6. The process for the preparation of high purity Isoglycyrrhizinate as claimed in any one of claims 1 to 5, wherein, In the step (2), the stirring temperature is 30-120℃, preferably 70-90℃; the stirring time is 0.5-10h, preferably 1-3h, and the temperature is cooled to 10-30℃.

7. The process for the preparation of high purity Isoglycyrrhizinate as claimed in any one of claims 1 to 6, wherein, In the step (2), the organic solvent is methanol, ethanol, dimethyl sulfoxide, dimethyl formamide, tetrahydrofuran, glacial acetic acid, preferably glacial acetic acid.

8. The process for the preparation of high purity Isoglycyrrhizinate as claimed in any one of claims 1 to 7, wherein, In the step (3), the weight-volume ratio of the high-purity methyl glycyrrhizinate to water is 1:3-20, preferably 1:3-5; the mass ratio of the high-purity methyl glycyrrhizinate to sodium hydroxide is 1:0.2-0.4; the hydrolysis temperature is 10-100℃, preferably 70-90℃; and the hydrolysis time is 1-5h, preferably 1-3h.

9. The process for the preparation of high purity Isoglycyrrhizinate as claimed in any one of claims 1 to 8, wherein, In the step (3), the weight-volume ratio of the high-purity methyl glycyrrhizinate to glacial acetic acid is 1:5-20, preferably 1:8-12; the stirring time is 3-4h; and the stirring temperature is 0℃.

10. The use of the method according to any one of claims 1-9 in the preparation of high-purity glycyrrhizic acid.

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