A green method for extracting glycyrrhizic acid

Abstract

This invention relates to the field of extraction technology and proposes a green method for extracting glycyrrhizic acid, comprising the following steps: S1, mixing licorice with a first solvent, extracting, separating, and obtaining a solid pretreated material; S2, mixing the solid pretreated material with a second solvent, extracting, separating, and obtaining an extract; S3, concentrating the extract, adding it to an aqueous two-phase extraction system, stirring, allowing it to stand and separate phases, obtaining an upper phase solution; S4, adding a third solvent to the upper phase solution, adjusting the pH to alkaline, separating phases, obtaining an aqueous phase solution, adjusting the pH of the aqueous phase solution to acidic, separating, obtaining a solid, drying the solid, and obtaining glycyrrhizic acid; the aqueous two-phase extraction agent in the system includes polyoxyethylene laurate solution and dipotassium hydrogen citrate solution. This technical solution solves the problem of insufficient yield and purity of glycyrrhizic acid in the extraction of glycyrrhizic acid from licorice in related technologies.

Description

Technical Field

[0001] This invention relates to the field of extraction technology, specifically to a green method for extracting glycyrrhizic acid. Background Technology

[0002] Glycyrrhizic acid is one of the main active components of licorice. Belonging to the triterpenoid class of compounds, it possesses various pharmacological activities, including anti-inflammatory, antiviral, hepatoprotective, and antioxidant effects, and is widely used in pharmaceuticals, food, and cosmetics. Traditional methods for extracting glycyrrhizic acid from licorice mainly include water extraction, alcohol extraction, and some organic solvent extraction methods.

[0003] Currently, reflux extraction using hot water or a certain concentration of ethanol-water solution is commonly employed. While this method is simple, it suffers from poor extraction selectivity, leading to difficulties in subsequent separation and purification, and ultimately resulting in unsatisfactory product yield and purity. To improve purity and yield, some methods introduce highly polar organic solvents (such as methanol, acetone, chloroform, dichloromethane, etc.) for extraction or crystallization. Although these methods improve separation efficiency to some extent, they also present problems such as high solvent consumption, residues, and environmental impact.

[0004] In recent years, some novel separation technologies have been gradually applied to the extraction and purification of glycyrrhizic acid, such as macroporous resin adsorption, supercritical fluid extraction, and membrane separation. However, macroporous resin adsorption suffers from problems such as limited adsorption capacity, large desorption solvent consumption, and high resin regeneration costs; supercritical fluid extraction equipment is expensive to invest in and has high operating costs, making it difficult to apply on a large scale industrially; and membrane separation technology is easily affected by the properties of the material, resulting in membrane fouling.

[0005] Therefore, a green method for extracting glycyrrhizic acid is proposed, which can reduce or avoid the use of toxic and harmful solvents while improving the extraction and separation effect of glycyrrhizic acid from licorice. This is of great significance for meeting people's demand for glycyrrhizic acid. Summary of the Invention

[0006] This invention proposes a green method for extracting glycyrrhizic acid, which solves the problem that the yield and purity of glycyrrhizic acid need to be improved when extracting glycyrrhizic acid from licorice in related technologies.

[0007] The technical solution of the present invention is as follows: This invention proposes a green method for extracting glycyrrhizic acid, comprising the following steps: S1. Licorice is mixed with the first solvent, extracted, and separated to obtain a solid pretreated product; S2. Mix the solid pretreatment material with the second solvent, extract, separate, and obtain the extract; S3. After concentrating the extract, add it to the aqueous two-phase extraction system, stir, and allow it to stand to separate the phases to obtain the upper phase solution. S4. After adding a third solvent to the upper phase solution, adjust the pH to alkaline, separate the phases to obtain an aqueous phase solution, adjust the pH of the aqueous phase solution to acidic, separate the phases to obtain a solid, and dry the solid to obtain glycyrrhizic acid. The aqueous two-phase extraction system includes a polyoxyethylene laurate solution and a dipotassium hydrogen citrate solution as the aqueous two-phase extractant. The first solvent includes n-butanol; The second solvent includes an aqueous solution of ethanol; The third solvent includes an aqueous solution of ethanol and ethyl acetate.

[0008] As a further technical solution, the mass fraction of the lauric acid polyoxyethylene ester solution is 5%~8%; The weight fraction of the dipotassium hydrogen citrate solution is 15% to 20%.

[0009] As a further technical solution, the volume ratio of the polyoxyethylene laurate solution to the dipotassium hydrogen citrate solution is 1:2~3.

[0010] In this invention, by optimizing the volume content of polyoxyethylene laurate solution and dipotassium hydrogen citrate solution, when the volume ratio of polyoxyethylene laurate solution to dipotassium hydrogen citrate solution is 1:2~3, the yield and purity of glycyrrhizic acid can be further improved, with the yield increasing to over 10.17% and the purity increasing to over 90.4%.

[0011] As a further technical solution, the first solvent also includes butyl acetate.

[0012] In this invention, when the first solvent also includes butyl acetate, the yield and purity of glycyrrhizic acid can be further improved by using butyl acetate and n-butanol together. The reason is speculated to be that the combined use of butyl acetate and n-butanol has a better effect on removing impurities from licorice, which is more conducive to the subsequent dissolution of glycyrrhizic acid, thereby further improving the yield and purity of glycyrrhizic acid.

[0013] As a further technical solution, the volume ratio of n-butanol to butyl acetate in the first solvent is 3~4:1.

[0014] In this invention, when the volume ratio of n-butanol to butyl acetate is 3-4:1, the yield and purity of glycyrrhizic acid can be further improved, with the yield increasing to over 10.98% and the purity increasing to over 92.7%.

[0015] As a further technical solution, the extraction process is carried out at a temperature of 50~60℃ for 1~2 hours.

[0016] As a further technical solution, the second solvent also includes an aqueous solution of a nonionic surfactant; The nonionic surfactant in the aqueous solution includes one or two of Tween-80 and fatty alcohol polyoxyethylene ether, preferably fatty alcohol polyoxyethylene ether.

[0017] As a further technical solution, the mass fraction of the nonionic surfactant aqueous solution is 4% to 6%, preferably 5%.

[0018] As a further technical solution, the volume ratio of the ethanol aqueous solution and the nonionic surfactant aqueous solution in the second solvent is 4:1; The volume ratio of the aqueous ethanol solution to ethyl acetate in the third solvent is 1 to 3:1.

[0019] As a further technical solution, in step S2, the extraction is reflux extraction, the temperature is 80~90℃, and the time is 1.5~2h.

[0020] As a further technical solution, the mass-to-volume ratio of licorice to the first solvent is 2g:15~30mL; The amount of the second solvent added is 10 to 15 times the mass of the solid pretreatment material.

[0021] As a further technical solution, in step S3, during the concentration process, the extract is concentrated to 40%~50% of its original volume; The amount of the aqueous two-phase extractant added is 6 to 8 times the volume of the concentrated liquid.

[0022] As a further technical solution, when a third solvent is added to the upper phase solution, the amount of the third solvent added is 4 to 6 times the volume of the upper phase solution.

[0023] As a further technical solution, the volume fraction of ethanol in the aqueous ethanol solution of the second solvent and the third solvent is independently 50%~60%, preferably 60%.

[0024] As a further technical solution, in step S4, when adjusting the pH to alkaline, the pH is specifically adjusted to 8-9 using a sodium hydroxide solution, wherein the mass fraction of the sodium hydroxide solution is 18%-25%, preferably 20%. When adjusting the pH to acidic, specifically, an acidic solution is used to adjust the pH to 2-3.5. The acidic solution includes either hydrochloric acid solution or sulfuric acid solution, and the weight fraction of the acidic solution is 15%-20%, preferably 20%.

[0025] The working principle and beneficial effects of this invention are as follows: 1. In the process of extracting glycyrrhizic acid in this invention, licorice is pretreated by soaking in n-butanol, and then the pretreated solid is extracted by water-soluble ethanol to obtain a crude extract containing glycyrrhizic acid. The crude extract is then extracted with a two-phase extractant composed of polyoxyethylene laurate solution and dipotassium hydrogen citrate solution. Finally, after pH adjustment, glycyrrhizic acid with relatively high yield and purity is obtained. When the aqueous two-phase extraction agent includes laurate polyoxyethylene ester solution and dipotassium hydrogen citrate solution, the extraction environment of this system is relatively mild, the system is stable, and the phase separation effect is quite obvious. Glycyrrhizic acid is mainly distributed in the upper phase solution containing laurate polyoxyethylene ester solution. This may be because laurate polyoxyethylene ester molecules in the system can form micelles to a certain extent, which tend to interact with the triterpene skeleton structure contained in glycyrrhizic acid. At the same time, the presence of dipotassium hydrogen citrate can regulate the ionic strength of the solution, causing glycyrrhizic acid to be biased towards the laurate polyoxyethylene ester solution phase, ultimately resulting in a good phase separation effect. This allows glycyrrhizic acid to be present to the maximum extent in the laurate polyoxyethylene ester solution phase, which is beneficial for further separation and ultimately improves the yield and purity of glycyrrhizic acid. In addition, the aqueous two-phase extraction system formed by laurate polyoxyethylene ester solution and dipotassium hydrogen citrate solution is more environmentally friendly, avoiding the large-scale use of toxic solvents in other extraction methods.

[0026] 2. In the process of extracting glycyrrhizic acid in this invention, n-butanol is used to pre-treat licorice for extraction. This can reduce the impact of impurities in licorice on the subsequent extraction of glycyrrhizic acid to a certain extent. At the same time, using n-butanol to pre-treat licorice for extraction allows the internal structure of licorice to be in a relatively relaxed state without dissolving glycyrrhizic acid, which facilitates better dissolution of glycyrrhizic acid in the subsequent extraction. This improves the yield and purity of glycyrrhizic acid to a certain extent. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] In the following examples and comparative examples, the fatty alcohol polyoxyethylene ether is model AEO-9; and the laurate polyoxyethylene ester is model LAE-9.

[0029] Example 1 A green method for extracting glycyrrhizic acid includes the following steps: S1. Mix 20g of licorice with 150mL of n-butanol, extract at 50℃ for 2h, centrifuge to obtain solid pretreated material; S2. Mix the above solid pretreatment material, a 60% volume fraction of ethanol aqueous solution and a 5% weight fraction of fatty alcohol polyoxyethylene ether solution (the sum of the added amounts of ethanol aqueous solution and fatty alcohol polyoxyethylene ether solution is 10 times the amount of solid pretreatment material, wherein the volume ratio of ethanol aqueous solution and fatty alcohol polyoxyethylene ether solution is 4:1), reflux at 80°C for 2 hours, centrifuge to obtain the extract; S3. After concentrating the above extract to 40% of its original volume, add it to the aqueous two-phase extraction system, stir, and allow it to stand for phase separation to obtain the upper phase solution; wherein the aqueous two-phase extraction agent in the aqueous two-phase extraction system is a 1:1 volume ratio of polyoxyethylene laurate solution (mass fraction 5%) and dipotassium hydrogen citrate solution (mass fraction 15%), and the amount of aqueous two-phase extraction agent added is 6 times the volume of the concentrated liquid; S4. Add a 60% ethanol aqueous solution and ethyl acetate in a volume ratio of 1:1 (the sum of the volume of the ethanol aqueous solution and ethyl acetate added is 4 times the volume of the upper phase solution) to the upper phase solution. Adjust the pH to 8 with a 20% sodium hydroxide solution, separate the phases to obtain an aqueous phase solution, adjust the pH of the aqueous phase solution to 2 with a 20% hydrochloric acid solution, separate the phases to obtain a solid, and dry the solid to obtain glycyrrhizic acid.

[0030] Example 2 A green method for extracting glycyrrhizic acid includes the following steps: S1. Mix 20g of licorice with 200mL of n-butanol, extract at 50℃ for 2h, centrifuge to obtain solid pretreated material; S2. Mix the above solid pretreatment material, a 60% (v / v) aqueous ethanol solution and a 5% (w / w) fatty alcohol polyoxyethylene ether solution (the sum of the amounts of the aqueous ethanol solution and the fatty alcohol polyoxyethylene ether solution added is 12 times the amount of the solid pretreatment material, wherein the volume ratio of the aqueous ethanol solution and the fatty alcohol polyoxyethylene ether solution is 4:1), reflux at 85°C for 1.5 h, centrifuge to obtain the extract; S3. After concentrating the above extract to 45% of its original volume, add it to the aqueous two-phase extraction system, stir, and allow it to stand for phase separation to obtain the upper phase solution; wherein the aqueous two-phase extractant in the aqueous two-phase extraction system is a 1:1 volume ratio of polyoxyethylene laurate solution (mass fraction 8%) and dipotassium hydrogen citrate solution (mass fraction 15%), and the amount of aqueous two-phase extractant added is 7 times the volume of the concentrated liquid; S4. Add a 60% ethanol aqueous solution and ethyl acetate in a volume ratio of 2:1 (the sum of the volume of the ethanol aqueous solution and ethyl acetate added is 5 times the volume of the upper phase solution) to the upper phase solution. Adjust the pH to 9 with a 20% sodium hydroxide solution, separate the phases to obtain an aqueous phase solution, adjust the pH of the aqueous phase solution to 3 with a 20% hydrochloric acid solution, separate the phases to obtain a solid, and dry the solid to obtain glycyrrhizic acid.

[0031] Example 3 A green method for extracting glycyrrhizic acid includes the following steps: S1. Mix 20g of licorice with 300mL of n-butanol, extract at 60℃ for 1h, centrifuge to obtain solid pretreated material; S2. Mix the above solid pretreatment material, a 60% volume fraction of ethanol aqueous solution, and a 5% weight fraction of fatty alcohol polyoxyethylene ether solution (the sum of the added ethanol aqueous solution and fatty alcohol polyoxyethylene ether solution is 15 times the mass of the solid pretreatment material, wherein the volume ratio of ethanol aqueous solution and fatty alcohol polyoxyethylene ether solution is 4:1), reflux at 90°C for 1.5 h, centrifuge to obtain the extract; S3. After concentrating the above extract to 50% of its original volume, add it to the aqueous two-phase extraction system, stir, and allow it to stand for phase separation to obtain the upper phase solution; wherein the aqueous two-phase extractant in the aqueous two-phase extraction system is a 1:1 volume ratio of polyoxyethylene laurate solution (mass fraction 8%) and dipotassium hydrogen citrate solution (mass fraction 20%), and the amount of aqueous two-phase extractant added is 8 times the volume of the concentrated liquid; S4. Add a 60% ethanol aqueous solution and ethyl acetate in a volume ratio of 3:1 (the sum of the volumes of the ethanol aqueous solution and ethyl acetate added is 6 times the volume of the upper phase solution) to the upper phase solution. Adjust the pH to 9 with a 20% sodium hydroxide solution, separate the phases to obtain an aqueous phase solution, adjust the pH of the aqueous phase solution to 3.5 with a 20% hydrochloric acid solution, separate the phases to obtain a solid, and dry the solid to obtain glycyrrhizic acid.

[0032] Example 4 The only difference between this embodiment and Embodiment 2 is that in this embodiment, the volume ratio of polyoxyethylene laurate solution to dipotassium hydrogen citrate solution is 1:4.

[0033] Example 5 The only difference between this embodiment and Embodiment 2 is that in this embodiment, the volume ratio of polyoxyethylene laurate solution to dipotassium hydrogen citrate solution is 1:2.

[0034] Example 6 The only difference between this embodiment and Embodiment 2 is that in this embodiment, the volume ratio of polyoxyethylene laurate solution to dipotassium hydrogen citrate solution is 1:3.

[0035] Example 7 The only difference between this embodiment and Example 6 is that in this embodiment, 200 mL of n-butanol is replaced with 100 mL of n-butanol and 100 mL of butyl acetate.

[0036] Example 8 The only difference between this embodiment and Example 6 is that in this embodiment, 200 mL of n-butanol is replaced with 180 mL of n-butanol and 20 mL of butyl acetate.

[0037] Example 9 The only difference between this embodiment and Example 6 is that in this embodiment, 200 mL of n-butanol is replaced with 150 mL of n-butanol and 50 mL of butyl acetate.

[0038] Example 10 The only difference between this embodiment and Example 6 is that in this embodiment, 200 mL of n-butanol is replaced with 160 mL of n-butanol and 40 mL of butyl acetate.

[0039] Comparative Example 1 The only difference between this comparative example and Example 2 is that, in this comparative example, the lauric acid polyoxyethylene ester solution (8% by mass) is replaced with an equal amount of fatty alcohol polyoxyethylene ether solution (8% by mass).

[0040] Comparative Example 2 The only difference between this comparative example and Example 2 is that in this comparative example, the dipotassium hydrogen citrate solution (mass fraction of 15%) is replaced with an equal amount of sodium phosphate solution (mass fraction of 15%).

[0041] Comparative Example 3 The only difference between this comparative example and Example 2 is that n-butanol is replaced with an equal amount of butyl acetate in this comparative example.

[0042] Comparative Example 4 The only difference between this comparative example and Example 2 is that n-butanol is replaced with an equal amount of petroleum ether in this comparative example.

[0043] Test case The extraction results of Examples 1-10 and Comparative Examples 1-4 are shown in Table 1.

[0044] Table 1 Extraction Results

[0045] As can be seen from Table 1, calculated according to the formula glycyrrhizic acid yield = glycyrrhizic acid mass / licorice mass × 100%, compared with Comparative Examples 1-2, the yield and purity of glycyrrhizic acid extracted in Examples 1-10 are improved. This indicates that when the aqueous two-phase extraction system uses polyoxyethylene laurate solution and dipotassium hydrogen citrate solution as the two-phase extractants, the extraction of the extract containing glycyrrhizic acid by the joint extraction of the extract containing glycyrrhizic acid by polyoxyethylene laurate solution and dipotassium hydrogen citrate solution can improve the final yield and purity of glycyrrhizic acid.

[0046] Compared with Comparative Examples 3-4, the yield and purity of glycyrrhizic acid extracted in Example 2 were improved to a certain extent, indicating that the pretreatment of licorice with n-butanol during the extraction of glycyrrhizic acid can improve the yield and purity of glycyrrhizic acid, and increase its purity to more than 88.4%.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A green method for extracting glycyrrhizic acid, characterized in that, Includes the following steps: S1. Licorice is mixed with the first solvent, extracted, and separated to obtain a solid pretreated product; S2. Mix the solid pretreatment material with the second solvent, extract, separate, and obtain the extract; S3. After concentrating the extract, add it to the aqueous two-phase extraction system, stir, and allow it to stand to separate the phases to obtain the upper phase solution. S4. After adding a third solvent to the upper phase solution, adjust the pH to alkaline, separate the phases to obtain an aqueous phase solution, adjust the pH of the aqueous phase solution to acidic, separate the phases to obtain a solid, and dry the solid to obtain glycyrrhizic acid. The aqueous two-phase extraction system includes a polyoxyethylene laurate solution and a dipotassium hydrogen citrate solution as the aqueous two-phase extractant. The first solvent includes n-butanol; The second solvent includes an aqueous solution of ethanol; The third solvent includes an aqueous solution of ethanol and ethyl acetate.

2. The method for green extraction of glycyrrhizic acid according to claim 1, characterized in that, The mass fraction of the polyoxyethylene laurate solution is 5%~8%; The weight fraction of the dipotassium hydrogen citrate solution is 15% to 20%.

3. The method for green extraction of glycyrrhizic acid according to claim 1, characterized in that, The volume ratio of the polyoxyethylene laurate solution to the dipotassium hydrogen citrate solution is 1:2~3.

4. The method for green extraction of glycyrrhizic acid according to claim 1, characterized in that, The first solvent also includes butyl acetate.

5. The method for green extraction of glycyrrhizic acid according to claim 4, characterized in that, The volume ratio of n-butanol to butyl acetate in the first solvent is 3~4:

1.

6. The method for green extraction of glycyrrhizic acid according to claim 1, characterized in that, The second solvent also includes an aqueous solution of a nonionic surfactant; The nonionic surfactant in the aqueous solution includes one or both of Tween-80 and fatty alcohol polyoxyethylene ether.

7. The method for green extraction of glycyrrhizic acid according to claim 6, characterized in that, The volume ratio of the aqueous ethanol solution to the aqueous nonionic surfactant solution in the second solvent is 4:1; The volume ratio of the aqueous ethanol solution to ethyl acetate in the third solvent is 1 to 3:

1.

8. The method for green extraction of glycyrrhizic acid according to claim 1, characterized in that, The mass-to-volume ratio of licorice to the first solvent is 2g:15~30mL; The amount of the second solvent added is 10 to 15 times the mass of the solid pretreatment material.

9. The method for green extraction of glycyrrhizic acid according to claim 1, characterized in that, In step S3, during the concentration process, the extract is concentrated to 40%~50% of its original volume; The amount of the aqueous two-phase extractant added is 6 to 8 times the volume of the concentrated liquid.

10. The method for green extraction of glycyrrhizic acid according to claim 1, characterized in that, When a third solvent is added to the upper phase solution, the amount of the third solvent added is 4 to 6 times the volume of the upper phase solution.

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