A glycyrrhetinic acid-based amino acid surfactant, its preparation method and application

Abstract

The present invention provides a glycyrrhetinic acid-based amino acid surfactant, a preparation method thereof and an application thereof. Starting from glycyrrhetinic acid, the present invention first reacts with benzyl chloride, and then introduces an amino acid functional group through an amidation reaction with methyl 4-aminobutyrate; then reacts with a base, acidifies, and further introduces an amino acid functional group through an amidation reaction with methyl 2-aminopropionate; and finally obtains the glycyrrhetinic acid-based amino acid surfactant through a reaction with a base. The surfactant obtained in the present invention has good aggregation ability, emulsion stability and foam stabilizing performance; at the same time, it has good green environmental protection characteristics and can be used in industrial processes such as pharmaceuticals, foods, and cosmetics.

Description

Technical Field

[0001] The present invention relates to a glycyrrhetinic acid-based bio-based amino acid surfactant, a preparation method thereof, and an application thereof, belonging to the field of synthesis and application of bio-based surfactants. Background Art

[0002] An emulsion is a thermodynamically unstable dispersion system composed of two or more immiscible liquid phases. Emulsions have wide applications in people's daily life and industrial production, such as in the fields of food, cosmetics, coatings, petrochemical industry, etc. The stability of emulsions has an important impact on their application performance. Surfactants are an important type of fine chemical products and are also commonly used emulsion stabilizers, and their application performance is closely related to their structure. Currently, surfactants used to stabilize emulsions, such as AES, AE, LAS, etc., are mainly prepared relying on petrochemical products, which is not conducive to carbon neutrality and carbon peak, and their degradability is poor and their environmental friendliness needs to be improved, which is not conducive to the sustainable development of the fields of surfactants and stabilized emulsions. With the iterative upgrading of green chemical engineering and green chemical products and the increasing requirements of people for the safety and biodegradability of fine chemical products, it has important practical application value to use naturally available raw materials to replace petrochemical products to prepare surfactants with excellent performance and use them to stabilize systems such as emulsions and foams.

[0003] Glycyrrhetinic acid is an important natural product, which has the advantages of being renewable and biodegradable. At the same time, it also has functions such as antibacterial and anti-inflammatory, antioxidant, anti-aging, and ultraviolet absorption. It can regulate the skin immune function, enhance the skin's disease resistance, eliminate inflammation, prevent allergies, etc. From the perspective of molecular structure, its pentacyclic triterpene skeleton has obvious hydrophobicity; the functional groups such as hydroxyl, enone, and carboxyl in its molecule have good reactivity and can introduce other substituents or active groups to be used to prepare a series of glycyrrhetinic acid-based compounds. In addition, amino acids are rich in sources, cheap and easy to obtain, and have high activity, high reactivity, and structural diversity. How to combine glycyrrhetinic acid and amino acids to prepare surfactants and make the obtained surfactants have excellent performance is worthy of further research; moreover, this will lay a foundation for the synthesis of new surfactants and their applications in new technology fields. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a glycyrrhetinic acid-based bio-based amino acid surfactant, a preparation method thereof, and an application thereof. The present invention uses the natural product glycyrrhetinic acid and amino acids as raw materials, and through multiple steps of reaction, introduces amino acids into the glycyrrhetinic acid molecule to synthesize a glycyrrhetinic acid-based surfactant. The surfactant obtained by the present invention has good aggregation ability, emulsion stability and foam stability performance; at the same time, it has good green environmental protection characteristics and can be used in industrial processes such as pharmaceuticals, foods, and cosmetics.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A glycyrrhetinic acid-based amino acid surfactant has a structure shown in Formula 1 below:

[0007]

[0008] The preparation method of the above glycyrrhetinic acid-based amino acid surfactant includes the steps:

[0009] (1) In dichloromethane, in the presence of triethylamine, glycyrrhetinic acid and benzyl chloride are reacted to prepare Compound 1-1;

[0010]

[0011] (2) In dichloromethane, in the presence of N,N'-dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt), Compound 1-1 and methyl 4-aminobutyrate are reacted to prepare Compound 1-2;

[0012]

[0013] (3) In a mixed solvent of ethanol and water, Compound 1-2 reacts with NaOH, and then is acidified to prepare Compound 1-3;

[0014]

[0015] (4) In dichloromethane, in the presence of N,N'-dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt), Compound 1-3 and methyl 2-aminopropionate are reacted to prepare Compound 1-4;

[0016]

[0017] (5) In a mixed solvent of ethanol and water, Compound 1-4 reacts with NaOH to prepare the glycyrrhetinic acid-based amino acid surfactant.

[0018] Preferably according to the present invention, in step (1), the mass ratio of glycyrrhetinic acid to the volume of dichloromethane is 0.05 - 0.5 g / mL.

[0019] Preferably according to the present invention, in step (1), the mass of triethylamine is 40 - 45% of the mass of glycyrrhetinic acid.

[0020] Preferably according to the present invention, in step (1), the molar ratio of glycyrrhetinic acid to benzyl chloride is 1:1.1 - 1.3.

[0021] Preferably according to the present invention, in step (1), benzyl chloride is added to the system containing glycyrrhetinic acid in a dropwise manner; during the dropwise addition, the temperature of the system is maintained at 0-5 °C; the dropwise addition process is carried out under stirring conditions.

[0022] Preferably according to the present invention, in step (1), the reaction temperature of glycyrrhetinic acid and benzyl chloride is room temperature. The reaction time is 8-12 h. The reaction of glycyrrhetinic acid and benzyl chloride is carried out under stirring conditions.

[0023] Preferably according to the present invention, in step (1), the post-treatment method of the reaction solution obtained from the reaction of glycyrrhetinic acid and benzyl chloride includes the steps of: adding water to the reaction solution, extracting with dichloromethane, washing the organic layer with water, drying, filtering, and subjecting the obtained filtrate to reduced pressure concentration and purification by silica gel column chromatography to obtain compound 1-1.

[0024] Preferably according to the present invention, in step (2), the mass-volume ratio of compound 1-1 to dichloromethane is 0.05-0.5 g / mL.

[0025] Preferably according to the present invention, in step (2), the mass ratio of N,N-dicyclohexylcarbodiimide, 1-hydroxybenzotriazole to compound 1-1 is 0.4-0.5:0.2-0.3:1.

[0026] Preferably according to the present invention, in step (2), the molar ratio of compound 1-1 to methyl 4-aminobutyrate is 1:1.1-1.3.

[0027] Preferably according to the present invention, in step (2), the reaction temperature of compound 1-1 and methyl 4-aminobutyrate is room temperature. The reaction time is 6-10 h. The reaction is carried out under stirring conditions.

[0028] Preferably according to the present invention, in step (2), the post-treatment method of the reaction solution obtained from the reaction of compound 1-1 and methyl 4-aminobutyrate includes the steps of: concentrating the reaction solution under reduced pressure to remove the solvent to obtain a solid; dissolving the obtained solid in ethyl acetate and placing it in an environment of -18 °C for 10-15 h, filtering to remove the precipitated solid, and subjecting the obtained filtrate to reduced pressure concentration and purification by silica gel column chromatography to obtain compound 1-2.

[0029] Preferably according to the present invention, in the mixed solvent of step (3), the volume ratio of ethanol to water is 80-120:1; the mass-volume ratio of compound 1-2 to the mixed solvent is 0.05-0.2 g / mL.

[0030] Preferably according to the present invention, in step (3), the molar ratio of compound 1-2 to NaOH is 1:1.1-1.3.

[0031] Preferably according to the present invention, in step (3), the reaction temperature of compound 1-2 and NaOH is 60-80 °C, the reaction time is 1-5 h, and the reaction is carried out under stirring conditions.

[0032] Preferably according to the present invention, in step (3), the reagent used for acidification is an aqueous hydrochloric acid solution with a mass concentration of 36% to 38%; the acidification is carried out until the pH of the system is 3-4.

[0033] Preferably according to the present invention, in step (3), the post-treatment method of the reaction solution obtained by the reaction of compound 1-2 and NaOH includes the steps of: cooling the reaction solution to room temperature, precipitating solids, and filtering; dispersing the obtained solids in absolute ethanol, filtering to obtain white solids; dissolving the white solids in water, adding an aqueous hydrochloric acid solution with a mass concentration of 36% to 38% dropwise to make the solution pH 3-4, extracting with ethyl acetate, washing the organic phase with water, drying, filtering, and concentrating the filtrate under reduced pressure to obtain compound 1-3.

[0034] Preferably according to the present invention, in step (4), the mass ratio of compound 1-3 to the volume of dichloromethane is 0.05-0.5 g / mL.

[0035] Preferably according to the present invention, in step (4), the mass ratio of N,N'-dicyclohexylcarbodiimide, 1-hydroxybenzotriazole to compound 1-3 is 0.3-0.5:0.2-0.3:1.

[0036] Preferably according to the present invention, in step (4), the molar ratio of compound 1-3 to methyl 2-aminopropionate is 1:1.1-1.3.

[0037] Preferably according to the present invention, in step (4), the reaction temperature of compound 1-3 and methyl 2-aminopropionate is room temperature, the reaction time is 6-10 h, and the reaction is carried out under stirring conditions.

[0038] Preferably according to the present invention, in step (4), the post-treatment method of the reaction solution obtained by the reaction of compound 1-3 and methyl 2-aminopropionate includes the steps of: concentrating the reaction solution under reduced pressure to remove the solvent to obtain a solid; dissolving the obtained solid in ethyl acetate and placing it in an environment of -18 °C for 10-15 h, filtering to remove the precipitated precipitate, and concentrating the obtained filtrate under reduced pressure and purifying it by silica gel column chromatography to obtain compound 1-4.

[0039] Preferably according to the present invention, in the mixed solvent of step (5), the volume ratio of ethanol to water is 80-120:1; the mass ratio of compound 1-4 to the volume of the mixed solvent is 0.04-0.2 g / mL.

[0040] Preferably according to the present invention, in step (5), the molar ratio of compound 1-4 to NaOH is 1:1.1-1.3.

[0041] Preferably according to the present invention, in step (5), the reaction temperature of compound 1-4 and NaOH is 60-80 °C, the reaction time is 1-5 h, and the reaction is carried out under stirring conditions.

[0042] Preferably according to the present invention, in step (5), the post-treatment method of the reaction solution obtained by the reaction of compound 1-4 and NaOH includes the steps of: cooling the reaction solution to room temperature, precipitating solids, and filtering; dispersing the obtained solids into absolute ethanol, and then obtaining the glycyrrhetinic acid bio-based amino acid surfactant through filtration and drying.

[0043] The application of the above-mentioned glycyrrhetinic acid bio-based amino acid surfactant is used as a surfactant in stabilizing emulsions or foams.

[0044] The synthetic route of the glycyrrhetinic acid bio-based amino acid surfactant of the present invention is as follows:

[0045]

[0046] Among them, Bn is benzyl; Me is methyl.

[0047] The technical features and beneficial effects of the present invention are as follows:

[0048] 1. The present invention uses glycyrrhetinic acid as the starting material, first reacts with benzyl chloride, and uses benzyl to protect the hydroxyl active group in glycyrrhetinic acid to avoid the hydroxyl group also participating in the reaction to produce by-products when glycyrrhetinic acid reacts with methyl 4-aminobutyrate. Then the obtained product introduces an amino acid functional group through an amidation reaction with methyl 4-aminobutyrate; then it reacts with a base and is acidified, and then further introduces an amino acid functional group through an amidation reaction with methyl 2-aminopropionate; finally, it reacts with a base to obtain the glycyrrhetinic acid bio-based amino acid surfactant. The preparation method of the present invention is simple; as a whole, the preparation method of the present invention enables the target product of the present invention to have a high yield and purity only when each step and each condition act together. Using glycyrrhetinic acid as the basic skeleton and modifying it with natural amino acids can conveniently obtain novel bio-based surfactants with potential antibacterial and anti-inflammatory functions, which conforms to the development trend of the current bio-based surfactant industry.

[0049] 2. The glycyrrhetinic acid-based bioamino acid surfactant of the present invention has good aggregation ability, and the critical micelle concentration value is 2.0 mmol / L. In the structure of the surfactant obtained in the present invention, the rigid skeleton structure of glycyrrhetinic acid and the amide groups contained in the molecule, combined with the complex interactions of other groups, can be firmly adsorbed on the surface of the emulsion or foam without desorption, thereby effectively enhancing the stability of the foam and emulsion; the surfactant of the present invention has excellent emulsion stabilization and foam stabilization properties, and the half-life of the formed foam can reach 1100 min. At the same time, the surfactant of the present invention has good green environmental protection characteristics and can be used in industrial processes such as pharmaceuticals, foods, and cosmetics. Description of the Drawings

[0050] Figure 1 1H NMR spectrum of the glycyrrhetinic acid-based amino acid surfactant 1 obtained in Example 5. 1

[0051] Figure 2 Graph of the change of surface tension γ of the glycyrrhetinic acid-based amino acid surfactant 1 obtained in Example 5 with concentration (25 °C).

[0052] Figure 3 Appearance photos of the n-decane / water emulsion stabilized by 1 mmol / L surfactant 1 in Application Example 1 (from left to right: (a) initial; (b): stabilized for 20 days; (c): stabilized for 60 days).

[0053] Figure 4 Micrographs of the n-decane / water emulsion stabilized by 1 mmol / L surfactant 1 in Application Example 1: (a) stabilized for 1 day; (b) stabilized for 30 days; (c) stabilized for 60 days (scale bar is 50 μm).

[0054] Figure 5 Graph of the change of foam volume of surfactant 1 with time in Application Example 2 (25 °C). Detailed Embodiments

[0055] The present invention will be further described below in conjunction with specific experimental examples and drawings, but not limited thereto.

[0056] At the same time, the methods described in the following embodiments are all conventional methods unless otherwise specified; the materials, unless otherwise specified, can be obtained from commercial channels.

[0057] ​Example 1: Synthesis of Compound 1-1: Glycyrrhetinic acid (9.4 g, 20 mmol) was dissolved in 100 mL of dichloromethane, and triethylamine (4.05 g, 40 mmol) was added with stirring. Under stirring conditions and at 0 - 5 °C, benzyl chloride (2.78 g, 22 mmol) was slowly added dropwise to the glycyrrhetinic acid solution. After the addition was completed in 1 h, the temperature was raised to room temperature, and the reaction was stirred for 12 h until the conversion of glycyrrhetinic acid was complete. After the reaction was completed, water was added to the mixture, and it was extracted with dichloromethane. The organic layer was washed with water 3 times, then dried over anhydrous magnesium sulfate, filtered by suction, and the filtrate was concentrated under reduced pressure. The product was purified by silica gel column chromatography (eluent: dichloromethane:methanol volume ratio = 20:1) to obtain white solid 1-1. Yield: 90%.

[0058] Example 2: Synthesis of Compound 1-2: Compound 1-1 (10 g, 17.4 mmol), N,N-dicyclohexylcarbodiimide (4.31 g, 20.9 mmol), and 1-hydroxybenzotriazole (2.82 g, 20.9 mmol) were dissolved in 100 mL of dichloromethane. Methyl 4-aminobutyrate (2.45 g, 20.9 mmol) was added to the reaction solution at room temperature, and the reaction was stirred overnight at room temperature for 10 h. After the reaction was completed, the solvent was removed by concentration under reduced pressure. The resulting solid was dissolved in ethyl acetate and placed in an environment at -18 °C for 12 h. The precipitated solid was filtered off, and the obtained filtrate was concentrated under reduced pressure and then purified by silica gel column chromatography (eluent: n-hexane:ethyl acetate volume ratio = 5:1) to obtain white solid 1-2. Yield: 85%.

[0059] Example 3: Synthesis of Compound 1-3: NaOH (0.65 g, 16.1 mmol) and 100 mL of absolute ethanol were added to a 250 mL three-necked reaction flask, and 1 g of water was added and stirred until NaOH was completely dissolved. Then compound 1-2 (9 g, 13.4 mmol) was added, and the temperature was raised to 70 °C, and the reaction was stirred for 3 h. After the reaction was completed, the reaction solution was cooled to room temperature, and a solid gradually precipitated. It was filtered by suction, and the obtained solid was dispersed in absolute ethanol and stirred for another 1 h, then filtered by suction to obtain a white solid. The white solid was dissolved in water, and concentrated hydrochloric acid with a mass concentration of 36% - 38% was added dropwise to make the solution acidic (pH = 4), and it was extracted with ethyl acetate. The organic phase was washed with water 3 times, then dried over anhydrous magnesium sulfate, filtered by suction, and the filtrate was concentrated under reduced pressure to obtain compound 1-3. Yield: 90%.

[0060] Example 4: Synthesis of Compound 1-4: Compound 1-3 (7 g, 10.6 mmol), N,N-dicyclohexylcarbodiimide (2.62 g, 12.7 mmol), and 1-hydroxybenzotriazole (1.72 g, 12.7 mmol) were dissolved in 100 mL of dichloromethane. Methyl 2-aminopropionate (1.31 g, 12.7 mmol) was added to the reaction solution at room temperature, and the reaction was stirred overnight at room temperature for 10 h. After the reaction was completed, the solvent was removed by concentration under reduced pressure. The obtained solid was dissolved in ethyl acetate and frozen at -18 °C for 12 h. The precipitated solid was removed by filtration. The obtained filtrate was concentrated under reduced pressure and purified by silica gel column chromatography (eluent: n-hexane:ethyl acetate volume ratio = 5:1) to obtain white solid 1-4. Yield: 80%.

[0061] Example 5: Synthesis of glycyrrhetinic acid-based amino acid surfactant 1: NaOH (0.4 g, 9.7 mmol) and 100 mL of absolute ethanol were added to a 250 mL three-necked reaction flask, and then 1 g of water was added. The mixture was stirred until NaOH was completely dissolved. Compound 1-4 (6 g, 8.1 mmol) was added, and the temperature was raised to 70 °C and stirred for 3 h. After the reaction was completed, the reaction solution was cooled to room temperature, and a solid gradually precipitated. The solid was filtered by suction. The obtained solid was dispersed in absolute ethanol and stirred for another 1 h, and then filtered by suction to obtain a white solid. After vacuum drying, the target product 1 was obtained. Yield 86%.

[0062] The glycyrrhetinic acid-based amino acid surfactant 1 obtained in this example 1 1H NMR spectrum is as Figure 1 shown. As can be seen from the figure, the target product was successfully prepared in this invention.

[0063] The glycyrrhetinic acid-based amino acid surfactant 1 obtained in this example was dissolved in water to prepare surfactant aqueous solutions with different concentrations; the relationship between the surface tension γ and the concentration of the surfactant aqueous solution was tested (25 °C), as Figure 2 shown. As can be seen from the figure, the critical micelle concentration value of surfactant 1 is 1.26 mmol·L -1 , and γ cmc is 35 mN·m -1 .

[0064] Application Example 1: Preparation of emulsion: In a series of 10 mL cylindrical vials, 2 mL of 1 mmol / L aqueous solution of the glycyrrhetinic acid-based amino acid surfactant prepared in Example 5 was prepared. 2 mL of n-decane was added as the oil phase, and the mixture was homogenized at 11000 r / min for 2 min in a homogenizer. The prepared emulsion was allowed to stand at room temperature for a period of time, and the state of the emulsion was observed as a function of time. The particle size of the emulsion was observed using a super-depth-of-field three-dimensional microscopic system, and the change in the particle size distribution of the emulsion particles over time was analyzed.

[0065] Figure 3 This is a photograph of the appearance of the emulsion in this application example (from left to right: (a) initial; (b): stable for 20 days; (c): stable for 60 days). The surfactant 1 participates in the emulsified n-decane / water system at a concentration of 1 mmol / L, which is an O / W type emulsion. It can be seen from the photograph of the appearance of the emulsion that the emulsion does not undergo phase separation after standing for 60 days, indicating that this surfactant has strong emulsifying properties.

[0066] Figure 4 This is a micrograph of the emulsion in this application example: (a) stable for 1 day; (b) stable for 30 days; (c) stable for 60 days (scale bar is 50 μm). It can be seen from the micrographs of the emulsion after standing for different times that for the system emulsified by 1 mmol / L surfactant, after standing for 30 days, the particle size of the oil droplets formed in the emulsion basically does not change. When the emulsion stands for 60 days, the original larger-sized oil droplets disappear, leaving only smaller-sized oil droplets, but the particle size distribution is still uniform, enabling the emulsion to be stable for a longer time.

[0067] Application Example 2: Preparation of foam: Use ultrapure water with a resistivity of 18.2 MΩ·cm to prepare an aqueous solution of glycyrrhetinic acid-based amino acid surfactant prepared in Example 5 with a molar concentration of 2 mmol / L; accurately measure 10 mL and add it to a 100 mL stoppered graduated cylinder, and add NaOH to adjust the pH value of the solution to 12. At 25 °C, shake it vigorously up and down 30 times to generate foam, and record the change in foam volume over time.

[0068] Figure 5 This is a graph showing the relationship between the foam volume of surfactant 1 and time in this application example (25 °C). As can be seen from the graph, the half-life of the foam formed by 1 mmol / L surfactant 1 is 1100 min. This indicates that this surfactant has good foam stability performance.

Claims

1. A glycyrrhetinic acid-based amino acid surfactant, characterized in that, It has the structure shown in Formula 1 below:

2. The preparation method of the glycyrrhetinic acid-based amino acid surfactant according to Claim 1 includes the steps: (1) In dichloromethane, in the presence of triethylamine, glycyrrhetinic acid and benzyl chloride are reacted to obtain Compound 1-1; (2) In dichloromethane, in the presence of N,N'-dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt), Compound 1-1 and methyl 4-aminobutyrate are reacted to obtain Compound 1-2; (3) In a mixed solvent of ethanol and water, Compound 1-2 reacts with NaOH, and then is acidified to obtain Compound 1-3; (4) In dichloromethane, in the presence of N,N'-dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt), Compound 1-3 and methyl 2-aminopropionate are reacted to obtain Compound 1-4; (5) In a mixed solvent of ethanol and water, Compound 1-4 reacts with NaOH to obtain the glycyrrhetinic acid-based amino acid surfactant.

3. The preparation method of the glycyrrhetinic acid-based amino acid surfactant according to claim 2, wherein, In step (1), one or more of the following conditions are included: i. The mass ratio of the glycyrrhetinic acid to the volume of dichloromethane is 0.05 - 0.5 g / mL; ii. The mass of the triethylamine is 40 - 45% of the mass of the glycyrrhetinic acid; iii. The molar ratio of the glycyrrhetinic acid to benzyl chloride is 1:1.1 - 1.3; iv. Benzyl chloride is added dropwise to the system containing glycyrrhetinic acid; during the dropwise addition, the temperature of the system is maintained at 0 - 5°C; the dropwise addition is carried out under stirring conditions; v. The reaction temperature of the glycyrrhetinic acid and benzyl chloride is room temperature; the reaction time is 8 - 12 h; the reaction of the glycyrrhetinic acid and benzyl chloride is carried out under stirring conditions; vi. The post-treatment method of the reaction solution obtained from the reaction of the glycyrrhetinic acid and benzyl chloride includes the steps: adding water to the reaction solution, extracting with dichloromethane, washing the organic layer with water, drying, filtering, and subjecting the obtained filtrate to reduced pressure concentration and silica gel column chromatography purification to obtain Compound 1-1.

4. The preparation method of the glycyrrhetinic acid-based amino acid surfactant according to claim 2, wherein, In step (2), one or more of the following conditions are included: i. The mass ratio of Compound 1-1 to the volume of dichloromethane is 0.05 - 0.5 g / mL; ii. The mass ratio of N,N'-dicyclohexylcarbodiimide, 1-hydroxybenzotriazole to Compound 1-1 is 0.4 - 0.5:0.2 - 0.3:1; iii. The molar ratio of Compound 1-1 to methyl 4-aminobutyrate is 1:1.1 - 1.3; iv. The reaction temperature of Compound 1-1 and methyl 4-aminobutyrate is room temperature; the reaction time is 6 - 10 h; the reaction is carried out under stirring conditions; v. The post-treatment method of the reaction solution obtained from the reaction of Compound 1-1 and methyl 4-aminobutyrate includes the steps: the reaction solution is concentrated under reduced pressure to remove the solvent to obtain a solid; the obtained solid is dissolved in ethyl acetate and placed in an environment at -18°C for 10 - 15 h, the precipitated precipitate is filtered off, and the obtained filtrate is concentrated under reduced pressure and purified by silica gel column chromatography to obtain Compound 1-2.

5. The preparation method of the glycyrrhetinic acid-based amino acid surfactant according to claim 2, wherein In step (3), one or more of the following conditions are included: i. In the mixed solvent, the volume ratio of ethanol to water is 80 - 120:1; the mass ratio of Compound 1 - 2 to the volume of the mixed solvent is 0.05 - 0.2 g / mL; ii. The molar ratio of Compound 1 - 2 to NaOH is 1:1.1 - 1.3; iii. The reaction temperature of Compound 1 - 2 and NaOH is 60 - 80 °C; the reaction time is 1 - 5 h; the reaction is carried out under stirring conditions; iv. The reagent used for acidification is an aqueous hydrochloric acid solution with a mass concentration of 36% - 38%; acidify until the pH of the system is 3 - 4; v. The post - treatment method of the reaction solution obtained from the reaction of Compound 1 - 2 and NaOH includes the steps: cool the reaction solution to room temperature, precipitate solids, and filter; disperse the obtained solids in absolute ethanol, filter to obtain white solids; dissolve the white solids in water, add an aqueous hydrochloric acid solution with a mass concentration of 36% - 38% to make the solution pH 3 - 4, extract with ethyl acetate, wash the organic phase with water, dry, filter, and concentrate the filtrate under reduced pressure to obtain Compound 1 - 3.

6. The preparation method of the glycyrrhetinic acid-based amino acid surfactant according to claim 2, characterized in that, In step (4), one or more of the following conditions are included: i. The mass ratio of Compound 1 - 3 to the volume of dichloromethane is 0.05 - 0.5 g / mL; ii. The mass ratio of N,N - dicyclohexylcarbodiimide, 1 - hydroxybenzotriazole to Compound 1 - 3 is 0.3 - 0.5:0.2 - 0.3:1; iii. The molar ratio of Compound 1 - 3 to methyl 2 - aminopropionate is 1:1.1 - 1.3; iv. The reaction temperature of Compound 1 - 3 and methyl 2 - aminopropionate is room temperature; the reaction time is 6 - 10 h; the reaction is carried out under stirring conditions; v. The post - treatment method of the reaction solution obtained from the reaction of Compound 1 - 3 and methyl 2 - aminopropionate includes the steps: concentrate the reaction solution under reduced pressure to remove the solvent to obtain solids; dissolve the obtained solids in ethyl acetate and place them in an environment of - 18 °C for 10 - 15 h, filter to remove the precipitated precipitate, and concentrate the obtained filtrate under reduced pressure and purify it by silica gel column chromatography to obtain Compound 1 - 4.

7. The preparation method of the glycyrrhetinic acid-based amino acid surfactant according to claim 2, characterized in that, In step (5), one or more of the following conditions are included: i. In the mixed solvent, the volume ratio of ethanol to water is 80 - 120:1; the mass ratio of Compound 1 - 4 to the volume of the mixed solvent is 0.04 - 0.2 g / mL; ii. The molar ratio of Compound 1 - 4 to NaOH is 1:1.1 - 1.3; iii. The reaction temperature of Compound 1 - 4 and NaOH is 60 - 80 °C; the reaction time is 1 - 5 h; the reaction is carried out under stirring conditions; iv. The post - treatment method of the reaction solution obtained from the reaction of Compound 1 - 4 and NaOH includes the steps: cool the reaction solution to room temperature, precipitate solids, and filter; disperse the obtained solids in absolute ethanol, and then filter and dry to obtain glycyrrhetinic acid bio - based amino acid surfactant.

8. The application of the glycyrrhetinic acid-based amino acid surfactant according to claim 1, characterized in that, It is used as a surfactant in stabilizing emulsions or foams.

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