A method for extracting and purifying glycyrrhetinic acid

Abstract

This invention provides a method for the extraction and purification of glycyrrhetinic acid, relating to the field of glycyrrhetinic acid technology. The method includes the following steps: drying and pulverizing licorice to obtain licorice powder; mixing the licorice powder with ethanol and ball milling; removing the ethanol after ball milling; performing supercritical CO2 extraction on the product; and recrystallizing the extract to obtain high-purity glycyrrhetinic acid. This invention optimizes the extraction conditions of glycyrrhetinic acid through ball milling pretreatment, and combined with supercritical CO2 extraction technology, significantly improves the extraction rate and product purity of glycyrrhetinic acid. It solves the problems of low extraction efficiency, high impurity content, and high process complexity in existing technologies, and has good application value.

Description

Technical Field

[0001] This invention relates to the field of glycyrrhetinic acid technology, and in particular to a method for the extraction and purification of glycyrrhetinic acid. Background Technology

[0002] Licorice (Glycyrrhiza uralensis Fisch.) is a perennial herb commonly found in various medicines, food additives, and high-end cosmetics. In medicine, licorice is known as the "King of Herbs," possessing properties that clear heat and detoxify, relieve cough and phlegm, tonify the spleen and stomach, and harmonize other medicines. It is widely used to treat spleen and stomach weakness, fatigue, palpitations, shortness of breath, cough with phlegm, abdominal and limb pain, carbuncles and boils, and to alleviate the toxicity of other drugs. Pharmacological research on the various components of licorice has spurred studies on its extraction, purification, and further analysis of its components.

[0003] Glycyrrhetinic acid (GA) is a triterpenoid compound extracted from licorice, commonly found in the products of glycyrrhizic acid hydrolysis. Glycyrrhetinic acid has adrenocorticotropic hormone (ACTH) activity, reducing urine output and sodium excretion while increasing potassium excretion, thus raising serum sodium and lowering serum calcium. It can be used for detoxification, anti-inflammation, antitussive, antitumor, anti-ulcer, and antibacterial purposes. Glycyrrhetinic acid can also be used as a treatment for liver fibrosis, and its antioxidant activity gives it potential as an antioxidant. These advantages lead to significant applications of glycyrrhetinic acid in the pharmaceutical, cosmetic, and food industries.

[0004] Currently, methods for extracting and purifying glycyrrhetinic acid include acid hydrolysis, cellulase-ultrasonic hydrolysis, microwave-pressurized hydrolysis, and biotransformation. Acid hydrolysis yields products with high purity but requires stringent reaction conditions and a long processing time. Cellulase-ultrasonic hydrolysis is relatively low-cost, simple to operate, and environmentally friendly, but the extract contains many impurities and has a low extraction rate. Microwave-pressurized hydrolysis is simple to operate and has high extraction efficiency, but research is still in the laboratory stage. Biotransformation has high extraction efficiency and mild reaction conditions, but its high cost has prevented its industrial application.

[0005] Chinese patent application CN107058443A discloses a method for preparing glycyrrhetinic acid. The specific steps include: S1: preparing a basic liquid culture medium in a fermenter; S2: adding glycyrrhizic acid to the basic liquid culture medium and inoculating the fermenter with a bacterial strain, followed by cultivation to obtain a fermentation broth; S3: breaking down the cell walls of the fermentation broth, filtering, extracting, concentrating, and drying to obtain crude glycyrrhetinic acid; S4: decolorization: dissolving the crude glycyrrhetinic acid and performing decolorization treatment, followed by filtration, recrystallization, further filtration, and drying to obtain the finished glycyrrhetinic acid product. This method utilizes biotransformation to prepare glycyrrhetinic acid from glycyrrhizic acid, but it suffers from high costs and is difficult to apply industrially. Summary of the Invention

[0006] In view of this, the present invention provides a method for the extraction and purification of glycyrrhetinic acid. The ball milling pretreatment of the present invention increases the specific surface area and solubility efficiency of licorice powder. Combined with supercritical CO2 extraction technology, it improves the solubility efficiency and extraction rate of the target component, avoids the problem of impurities introduced by entrainment agents, and significantly improves the extraction purity and efficiency. This effectively solves the problems of low extraction efficiency, high impurity content, and complex processes in traditional methods, and has good industrial application value.

[0007] The method for extracting and purifying glycyrrhetinic acid according to the present invention includes the following steps:

[0008] Licorice was dried and pulverized to obtain licorice powder. The licorice powder was mixed with ethanol and ball-milled. After ball milling, the ethanol was removed, and the product was subjected to supercritical CO2 extraction. The extract was recrystallized to obtain high-purity glycyrrhetinic acid.

[0009] Preferably, the drying temperature is 35℃~65℃, and the moisture content of the dried licorice is ≤15%. More preferably, the drying temperature is 45℃~60℃, and the moisture content of the dried licorice is ≤12%.

[0010] Preferably, the concentration of the ethanol is 80% to 95%. More preferably, the concentration of the ethanol is 85% to 95%.

[0011] Preferably, the amount of ethanol used is 12 wt.% to 20 wt.% of the licorice powder. More preferably, the amount of ethanol used is 15 wt.% of the licorice powder.

[0012] Preferably, during the ball milling process, the ball-to-material ratio is (4-6):1, the ball mill jar filling amount is 50%-60%, the rotation speed is 800-1000 r / min, and the ball milling time is 35-50 min. More preferably, during the ball milling process, the ball-to-material ratio is 5:1, the ball mill jar filling amount is 55%, the rotation speed is 1000 r / min, and the ball milling time is 45-50 min.

[0013] Preferably, the supercritical CO2 extraction pressure is 15–30 MPa, the extraction temperature is 40°C–50°C, and the extraction time is 1–3 h. More preferably, the supercritical CO2 extraction pressure is 20–25 MPa, the extraction temperature is 45°C, and the extraction time is 2 h.

[0014] This invention optimizes the extraction conditions of glycyrrhetinic acid through ball milling pretreatment, significantly increasing the specific surface area of ​​licorice powder, releasing intracellular glycyrrhetinic acid, and improving particle uniformity and dissolution efficiency. Combined with supercritical CO2 extraction technology, it enhances the extraction rate and the dissolution efficiency of the target component, thereby significantly improving the extraction rate. By replacing entrainers with physical pretreatment, the introduction of impurities can be avoided, resulting in a significant increase in the purity of glycyrrhetinic acid and making subsequent purification processes more efficient and simpler. Simultaneously, the combination of ball milling and supercritical CO2 extraction reduces extraction time, lowering energy consumption and production costs.

[0015] This invention ensures the efficiency and stability of each step in the drying, ball milling, supercritical CO2 extraction, and subsequent purification processes by strictly limiting parameters such as temperature, time, pressure, and slurry ratio, thereby ensuring the efficient extraction and high-purity preparation of glycyrrhetinic acid.

[0016] This invention solves the problems of low extraction efficiency, high impurity content, and high process complexity of glycyrrhetinic acid in the prior art, and has good application value. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings.

[0018] Figure 1 This is a process flow diagram of the extraction and purification method of glycyrrhetinic acid according to the present invention. Detailed Implementation

[0019] The technical solution 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.

[0020] This invention provides a method for the extraction and purification of glycyrrhetinic acid, specifically including the following steps:

[0021] Licorice was dried and pulverized to obtain licorice powder. The licorice powder was mixed with ethanol and ball-milled. After ball milling, the ethanol was removed, and the product was subjected to supercritical CO2 extraction. The extract was recrystallized to obtain high-purity glycyrrhetinic acid.

[0022] The first step of this invention is to prepare licorice powder after drying. Specifically, the licorice is dried at 35℃ to 65℃ until the moisture content is ≤15%, then pulverized and passed through an 80-120 mesh sieve. In some preferred embodiments of this invention, the drying temperature is 45℃ to 60℃, and the moisture content of the dried licorice is ≤12%.

[0023] This invention removes excess moisture from licorice through drying, reducing its water content and preventing oxidation caused by excessive moisture, thus protecting glycyrrhetinic acid from oxidative degradation. Furthermore, pulverizing the dried licorice into appropriately sized particles (passing through an 80-120 mesh sieve) appropriately increases the particle surface area and powder uniformity, allowing for more effective ball milling with ethanol and improving milling efficiency. This invention also limits the drying temperature and powder particle size, primarily to ensure efficiency while avoiding the decomposition or reduced activity of glycyrrhetinic acid, which could affect subsequent preparation and purification processes.

[0024] The second step of this invention is to mix the licorice powder with ethanol and then ball mill it. After ball milling, the ethanol is removed to obtain the ball-milled product. Specifically, the licorice powder is mixed with ethanol of 80% to 95% concentration, accounting for 12 wt.% to 20 wt.% of the licorice powder, and then ball-milled for 35 to 50 minutes. The ball-to-powder ratio is (4 to 6):1, the ball mill jar is filled to 50% to 60%, and the rotation speed is 800 to 1000 r / min. After ball milling, a licorice slurry is obtained, and the ethanol is removed after ball milling. In some preferred embodiments of this invention, the licorice powder is mixed with ethanol of 85% to 95% concentration, accounting for 15 wt.% of the licorice powder, and then ball-milled for 45 to 50 minutes. The ball-to-powder ratio is 5:1, the ball mill jar is filled to 55%, and the rotation speed is 1000 r / min. After ball milling, a licorice slurry is obtained.

[0025] The core of this invention is to improve the efficiency and purity of glycyrrhetinic acid extraction through ball milling. First, ball milling further refines the licorice powder using mechanical force, reducing particle size and significantly increasing the specific surface area. This structural optimization facilitates more effective contact and dissolution of glycyrrhetinic acid by the solvent during subsequent supercritical CO2 extraction, improving extraction efficiency. Furthermore, when mixing licorice powder with ethanol, ball milling ensures that ethanol is evenly distributed on the surface of the powder particles, forming a uniform slurry, which is crucial for the stability and consistency of the extraction process. A uniform slurry also avoids the problem of excessively high or low concentrations in certain areas. The ball milling process also disrupts the licorice cell walls, releasing intracellular glycyrrhetinic acid and reducing extraction resistance, thus providing a more ideal material form for subsequent extraction steps. To ensure that ball milling achieves the desired results, this invention strictly limits parameters such as the ball-to-powder ratio, loading amount, rotation speed, and milling time to precisely control the slurry viscosity and particle distribution characteristics, providing suitable material flowability and extraction performance for subsequent processes. Furthermore, the use of ethanol as the milling medium in this invention not only uniformly wets the licorice powder, reducing excessive friction and heat accumulation between particles during milling, but also partially dissolves the target component, releasing glycyrrhetinic acid from the cell wall or matrix, thus laying the foundation for subsequent supercritical CO2 extraction. In addition, milling physically modifies the licorice powder by refining particles, disrupting cell wall structure, increasing specific surface area, improving particle uniformity, and introducing surface defects, thereby significantly improving its extraction performance. The refined particles have a larger specific surface area and higher surface activity, enhancing contact and dissolution efficiency with supercritical CO2; the broken cell walls release more target components, making them easier to dissolve and migrate with supercritical CO2. Moreover, the ethanol solvent introduced during milling can adjust the polarity of the licorice powder, further reducing the binding strength of the target component, forming a synergistic effect with supercritical CO2, ultimately accelerating the extraction process and significantly improving the extraction rate and purity of glycyrrhetinic acid.

[0026] While existing technologies exist for the extraction of glycyrrhetinic acid using supercritical CO2, most require the use of entrainers to improve extraction efficiency. However, using entrainers in supercritical extraction carries certain risks. First, entrainer residues require additional removal steps, increasing process complexity. Second, entrainers affect the solubility of supercritical CO2. In our research, we found that while using entrainers increases the extraction rate, the purity of the obtained glycyrrhetinic acid is significantly reduced, making subsequent purification more difficult and increasing overall costs. Therefore, this invention employs ball milling pretreatment to improve the extraction rate while reducing impurities in the extract, thereby obtaining glycyrrhetinic acid with higher purity.

[0027] The third step of this invention is to perform supercritical CO2 extraction on the slurry, specifically: the ball-milled product is subjected to supercritical CO2 extraction at a pressure of 15–30 MPa and a temperature of 40–50°C for 1–3 hours. In some preferred embodiments of this invention, the supercritical CO2 extraction pressure is 20–25 MPa, the extraction temperature is 45°C, and the extraction time is 2 hours.

[0028] Supercritical fluid extraction (SFE) is a technique that utilizes the dissolving power of supercritical fluids to separate target components from solids or liquids. Supercritical fluids are substances that exhibit gaseous and liquid properties when the temperature and pressure exceed their critical points. The most commonly used supercritical fluid is carbon dioxide (CO2) due to its safety, non-toxicity, low cost, availability, and relatively low critical point (critical temperature 31.1℃, critical pressure 7.38MPa). Supercritical fluid extraction has been widely applied in industries such as pharmaceuticals, food, chemicals, petroleum, and coal. This invention selects supercritical CO2 extraction technology for the extraction and purification of glycyrrhetinic acid, avoiding the risk of contamination of the target product by organic solvents and preserving the natural properties and active ingredients of glycyrrhetinic acid. The extraction conditions of supercritical CO2 are mild and do not lead to the degradation of glycyrrhetinic acid. This invention improves the selectivity of the extraction process by ball milling the sample, significantly reducing extraction time and improving overall production efficiency.

[0029] The fourth step of this invention is the recrystallization of the extract, specifically: adjusting the pH of the extract to 2.0, filtering after complete precipitation of glycyrrhetinic acid, and finally crystallizing with dichloromethane 1 to 2 times to obtain high-purity glycyrrhetinic acid.

[0030] This invention optimizes the extraction conditions of glycyrrhetinic acid through ball milling pretreatment and solves the problems of low extraction efficiency, high impurity content and high process complexity of glycyrrhetinic acid in the prior art by combining supercritical CO2 extraction technology, and has good application value.

[0031] To further illustrate the present invention, the following embodiments provide a detailed description. All raw materials used in the following embodiments of the present invention are commercially available, wherein the licorice raw material is the root and rhizome of the legume plant *Glycyrrhizauralensis* Fisch.

[0032] Unless otherwise specified, all experiments were repeated three times. Analysis of variance (ANOVA) and Duncan's multiple comparison analysis were performed using SPSS 21.0. Results are expressed as mean ± standard deviation, and p < 0.05 was considered statistically significant.

[0033] Example 1: Effect of ethanol concentration on the extraction and purification of glycyrrhizic acid

[0034] Licorice was dried at 45℃ to a moisture content of 12%, then pulverized and passed through a 120-mesh sieve to obtain licorice powder. The licorice powder was mixed with 15 wt.% of ethanol of different concentrations (70%, 80%, 85%, 90%, 95%, and anhydrous ethanol) and ball-milled for 50 min at a ball-to-powder ratio of 5:1, a ball mill jar filling of 55%, and a rotation speed of 1000 r / min to obtain a licorice slurry. After ball milling, the ethanol was removed. The ball-milled product was subjected to supercritical CO2 extraction at 25 MPa and 45℃ for 2 h. The pH of the extract was adjusted to 2.0, and after complete precipitation of glycyrrhetinic acid, it was filtered. Finally, it was crystallized twice with dichloromethane to obtain high-purity glycyrrhetinic acid.

[0035] The extraction rate of glycyrrhetinic acid was calculated and the purity of glycyrrhetinic acid in the extract was detected. The results are shown in Table 1.

[0036] Table 1. Effect of ethanol concentration on the extraction and purification of glycyrrhizic acid.

[0037] 70％ 0.0174±0.0003f 94.03±0.02e 75％ 0.0203±0.0002e 94.82±0.04d 80％ 0.0258±0.0005d 95.91±0.05c 85％ 0.0262±0.0006cd 95.95±0.05bc 90％ 0.0267±0.0004bc 96.03±0.04b 95％ 0.0273±0.0003ab 96.05±0.03a Anhydrous ethanol 0.0275±0.0002a 96.01±0.06ab

[0038] Table 1 shows that the concentration of ethanol during ball milling has a significant impact on the final extraction rate and purity of glycyrrhetinic acid. Considering both extraction and purification costs and effects, this invention selects 80%–95% ethanol for ball milling licorice. Within this range, efficient extraction and purification of glycyrrhetinic acid with high purity can be achieved. However, where practical conditions permit, this invention preferably uses 85%–95% ethanol for ball milling licorice to obtain better extraction and purification results.

[0039] Example 2: Effect of pellet-to-material ratio on glycyrrhizic acid extraction and purification.

[0040] Licorice was dried at 45℃ to a moisture content of 12% and then pulverized and passed through a 120-mesh sieve. The licorice powder was mixed with 95% ethanol (15 wt.% of the licorice powder) and ball-milled for 50 min. The ball-to-powder ratios were 3:1, 4:1, 5:1, 6:1, 7:1, and 8:1, respectively. The ball mill jar was filled to 55% capacity and the rotation speed was 1000 r / min. After ball milling, a licorice slurry was obtained, and the ethanol was removed after the ball milling was completed. The ball-milled product was then subjected to supercritical CO2 extraction at 25 MPa and 45℃ for 2 h. The pH of the extract was adjusted to 2.0, and after complete precipitation of glycyrrhetinic acid, it was filtered. Finally, it was crystallized twice with dichloromethane to obtain high-purity glycyrrhetinic acid.

[0041] The extraction rate of glycyrrhetinic acid was calculated and the purity of glycyrrhetinic acid in the extract was detected. The results are shown in Table 2.

[0042] Table 2. Effect of pellet ratio on glycyrrhizic acid extraction and purification efficiency.

[0043] 3:1 0.2331±0.0002b 94.99±0.08c 4:1 0.2692±0.0002a 95.51±0.04b 5:1 0.2755±0.0005a 96.03±0.03a 6:1 0.2647±0.0007a 96.07±0.03a 7:1 0.1980±0.0003c 91.54±0.04d 8:1 0.1645±0.0004d 88.36±0.06e

[0044] Table 2 shows that the ball-to-material ratio has a significant impact on the final extraction rate and purity of glycyrrhetinic acid during ball milling. Considering both extraction and purification costs and effects, this invention selects a ball-to-material ratio of (4–6):1 for ball milling licorice. Within this range, efficient extraction and purification of glycyrrhetinic acid with high purity can be achieved. Table 2 also shows that excessive ball milling leads to a significant decrease in the extraction rate and purity of glycyrrhetinic acid, possibly related to the heat generated during the ball milling process.

[0045] Example 3: Effect of ball milling speed on the extraction and purification of glycyrrhizic acid

[0046] Licorice was dried at 45℃ to a moisture content of 12% and then pulverized and passed through a 120-mesh sieve. The licorice powder was mixed with 95% ethanol (15 wt.% of the licorice powder) and ball-milled for 50 min at a ball-to-powder ratio of 5:1 and a ball mill jar filling capacity of 55%. The rotation speeds were 600, 700, 800, 900, 1000, 1100, and 1200 r / min, respectively, to obtain a licorice slurry. After ball milling, the ethanol was removed. The ball-milled product was subjected to supercritical CO2 extraction at 25 MPa and 45℃ for 2 h. The pH of the extract was adjusted to 2.0, and after complete precipitation of glycyrrhetinic acid, it was filtered. Finally, it was crystallized twice with dichloromethane to obtain high-purity glycyrrhetinic acid.

[0047] The extraction rate of glycyrrhetinic acid was calculated and the purity of glycyrrhetinic acid in the extract was detected. The results are shown in Table 3.

[0048] Table 3 Effect of ball milling speed on the extraction and purification of glycyrrhizic acid

[0049] 600 0.2058±0.0008d 95.08±0.05c 700 0.2374±0.0006bc 95.72±0.02c 800 0.2625±0.0005ab 96.05±0.07a 900 0.2697±0.0004a 96.01±0.01a 1000 0.2741±0.0001a 96.06±0.06a 1100 0.2557±0.0006ab 95.01±0.03c 1200 0.2134±0.0004cd 93.54±0.04d

[0050] Table 3 shows that the ball milling speed has a significant impact on the final extraction rate and purity of glycyrrhetinic acid during ball milling. Considering both extraction and purification costs and effects, this invention selects a ball milling speed of 800–1000 r / min for licorice. Within this range, efficient extraction and purification of glycyrrhetinic acid with high purity can be achieved. Table 3 also shows that excessively high ball milling speeds can lead to over-milling, thus reducing the extraction rate and purity of glycyrrhetinic acid, but the impact is less severe than that of the ball-to-material ratio.

[0051] Example 4: Effect of ball milling time on the extraction and purification of glycyrrhizic acid

[0052] Licorice was dried at 45℃ to a moisture content of 12% and then pulverized and passed through a 120-mesh sieve. The licorice powder was mixed with 15 wt.% 95% ethanol and ball-milled for 30, 35, 40, 45, 50, 55, and 60 min respectively, with a ball-to-powder ratio of 5:1, a ball mill jar filling of 55%, and a rotation speed of 1000 r / min. After ball milling, a licorice slurry was obtained, and the ethanol was removed after ball milling. The ball-milled product was then subjected to supercritical CO2 extraction at 25 MPa and 45℃ for 2 h. The pH of the extract was adjusted to 2.0, and after complete precipitation of glycyrrhetinic acid, it was filtered. Finally, it was crystallized twice with dichloromethane to obtain high-purity glycyrrhetinic acid.

[0053] The extraction rate of glycyrrhetinic acid was calculated and the purity of glycyrrhetinic acid in the extract was detected. The results are shown in Table 4.

[0054] Table 4. Effect of ball milling time on the extraction and purification of glycyrrhizic acid.

[0055] 30 0.2223±0.0003f 95.03±0.03c 35 0.2702±0.0002c 95.97±0.07a 40 0.2701±0.0001c 96.08±0.08a 45 0.2713±0.0003b 96.05±0.05a 50 0.2749±0.0001a 96.07±0.07a 55 0.2598±0.0002d 95.34±0.04b 60 0.2446±0.0006e 94.43±0.08d

[0056] Table 4 shows that the ball milling time has a significant impact on the final extraction rate and purity of glycyrrhetinic acid. Considering both extraction and purification costs and effects, this invention limits the ball milling time to 35–50 min. Within this range, efficient extraction and purification of glycyrrhetinic acid with high purity can be achieved. However, where practical conditions permit, this invention preferably uses a ball milling time of 45–50 min to obtain better extraction and purification results. Table 4 also shows that extending the ball milling time can lead to over-milling, thereby reducing the extraction rate and purity of glycyrrhetinic acid. However, similarly, this factor has a lower impact on the extraction rate and purity than the ball-to-material ratio.

[0057] Example 5: A method for extracting and purifying glycyrrhetinic acid, the steps of which are as follows:

[0058] S1. Dry the licorice at 45℃ until the moisture content is 12%, then pulverize it and pass it through a 120-mesh sieve;

[0059] S2. Mix licorice powder with 95% ethanol (15 wt.% of licorice powder) and ball mill for 50 min. The ball-to-powder ratio is 5:1, the ball mill jar is filled to 55%, and the rotation speed is 1000 r / min. After ball milling, licorice slurry is obtained. After ball milling, the ethanol is removed.

[0060] S3. The ball-milled product was subjected to supercritical CO2 extraction at 25 MPa and 45 °C for 2 h.

[0061] S4. Adjust the pH of the extract to 2.0. After the glycyrrhetinic acid is completely precipitated, filter it and finally crystallize it twice with dichloromethane to obtain high-purity glycyrrhetinic acid.

[0062] The glycyrrhetinic acid extraction rate of this embodiment was (0.0278±0.002)%, and the purity of glycyrrhetinic acid in the extract was (96.07±0.05)%.

[0063] Example 6: A method for extracting and purifying glycyrrhetinic acid, the steps of which are as follows:

[0064] S1. Dry the licorice at 60℃ until the moisture content is 10%, then pulverize it and pass it through a 120-mesh sieve;

[0065] S2. Glycyrrhiza powder is mixed with ethanol of 85% concentration, which accounts for 15 wt.% of licorice powder, and then ball-milled for 45 min. The ball-to-powder ratio is 5:1, the ball mill jar is filled with 55% of the powder, and the rotation speed is 800 r / min. After ball milling, licorice slurry is obtained. After ball milling, the ethanol is removed.

[0066] S3. The ball-milled product was subjected to supercritical CO2 extraction at 25 MPa and 45 °C for 2 h.

[0067] S4. Adjust the pH of the extract to 2.0. After the glycyrrhetinic acid is completely precipitated, filter it and finally crystallize it twice with dichloromethane to obtain high-purity glycyrrhetinic acid.

[0068] The glycyrrhetinic acid extraction rate of this embodiment was (0.0270±0.004)%, and the purity of glycyrrhetinic acid in the extract was (96.01±0.08)%.

[0069] Comparative Example 1

[0070] A method for extracting and purifying glycyrrhetinic acid, comprising the following steps:

[0071] S1. Dry the licorice at 60℃ until the moisture content is 10%, then pulverize it and pass it through a 120-mesh sieve;

[0072] S2. Licorice powder was subjected to supercritical CO2 extraction at 25 MPa and 45 °C for 2 hours.

[0073] S3. Adjust the pH of the extract to 2.0. After the glycyrrhetinic acid is completely precipitated, filter it and finally crystallize it twice with dichloromethane to obtain high-purity glycyrrhetinic acid.

[0074] The glycyrrhetinic acid extraction rate of this embodiment was (0.0191±0.001)%, and the purity of glycyrrhetinic acid in the extract was (91.64±0.09)%.

[0075] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for extracting and purifying glycyrrhetinic acid, characterized in that, Includes the following steps: Licorice was dried and pulverized to obtain licorice powder. The licorice powder was mixed with ethanol and ball-milled. After ball milling, the ethanol was removed, and the product was subjected to supercritical CO2 extraction. The extract was recrystallized to obtain high-purity glycyrrhetinic acid. During the ball milling process, the ball-to-material ratio is (4~6):1, the ball mill jar filling amount is 50%~60%, the rotation speed is 800~1000 r / min, and the ball milling time is 35~50 min; The concentration of the ethanol is 80% to 95%.

2. The method for extraction and purification of glycyrrhetinic acid according to claim 1, characterized in that, The drying temperature is 35℃~65℃, and the moisture content of the dried licorice is ≤15%.

3. The method for extracting and purifying glycyrrhetinic acid according to claim 2, characterized in that, The drying temperature is 45℃~60℃, and the moisture content of the dried licorice is ≤12%.

4. The method for extracting and purifying glycyrrhetinic acid according to claim 1, characterized in that, The concentration of the ethanol is 85% to 95%.

5. The method for extracting and purifying glycyrrhetinic acid according to claim 1, characterized in that, The amount of ethanol used is 12wt% to 20wt% of the licorice powder.

6. The method for extracting and purifying glycyrrhetinic acid according to claim 1, characterized in that, During the ball milling process, the ball-to-material ratio is 5:1, the ball mill jar is filled with 55% of its capacity, the rotation speed is 1000 r / min, and the milling time is 45~50 min.

7. The method for extracting and purifying glycyrrhetinic acid according to claim 1, characterized in that, The supercritical CO2 extraction pressure is 15~30 MPa, the extraction temperature is 40℃~50℃, and the extraction time is 1~3 h.

8. The method for extracting and purifying glycyrrhetinic acid according to claim 7, characterized in that, The supercritical CO2 extraction pressure is 20~25 MPa, the extraction temperature is 45℃, and the extraction time is 2 h.

Images