Glycyrrhiza polysaccharide, preparation method thereof and application of glycyrrhiza polysaccharide in preparation of medicine for treating acute lung injury

Abstract

The invention relates to the field of biological medicine, in particular to glycyrrhiza polysaccharide, a preparation method thereof and application of the glycyrrhiza polysaccharide to preparation of medicine for treating acute lung injury. The preparation method comprises the following steps: adding water into the radix liquiritiae, boiling, and extracting to obtain a water extract; and adding an alcoholic solution with the volume concentration of 70-75% into the water extract to carry out alcohol precipitation treatment, wherein the volume ratio of the water extract to the alcoholic solution is (1.20-1.30): 1. The glycyrrhiza polysaccharide provided by the invention has the effects of protecting lung tissue epithelial barrier, resisting oxidation and inflammation, regulating intestinal flora and the like. The preparation method is simple, convenient and efficient, the product forms are diversified, the medicine is suitable for clinical and animal models, and a multi-target intervention strategy is provided for acute lung injury treatment.

Description

Technical Field

[0001] The present invention relates to the field of biomedicine, and relates to a glycyrrhizin polysaccharide, a preparation method thereof, and an application thereof in the preparation of a drug for treating acute lung injury. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Acute Lung Injury (ALI) is a serious clinical condition, manifested as inflammation between alveoli and gas exchange disorders. Currently, the clinical treatment for acute lung injury mainly includes supportive therapies, such as mechanical ventilation. Antibiotics are used to control infections, and fluid management is used to correct the body's volume status. However, these treatment methods often cannot effectively block the injury process or restore lung function.

[0004] In recent years, the treatment research for ALI has gradually increased, mainly focusing on the following aspects: mainly reducing the pulmonary inflammatory response, and controlling the release of inflammatory mediators by using steroids, non-steroidal anti-inflammatory drugs, etc. However, long-term use of steroids may bring adverse reactions. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a glycyrrhizin polysaccharide, a preparation method thereof, and an application thereof in the preparation of a drug for treating acute lung injury. The glycyrrhizin polysaccharide provided by the present invention has the effects of protecting the epithelial barrier of lung tissue, antioxidant and anti-inflammatory, and regulating intestinal flora.

[0006] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0007] In the first aspect, a preparation method of a glycyrrhizin polysaccharide, comprising the following steps:

[0008] Adding water to red-skin licorice and boiling for extraction to obtain an aqueous extract;

[0009] Adding an alcohol solution with a volume concentration of 70-75% to the aqueous extract for alcohol precipitation, and the volume ratio of the aqueous extract to the alcohol solution is 1.20-1.30:1.

[0010] Glycyrrhiza polysaccharide is a natural polysaccharide compound extracted from the roots of Glycyrrhiza uralensis Fisch., Glycyrrhiza glabra L., and Glycyrrhiza inflata Bat. There are certain differences in the Glycyrrhiza polysaccharides contained in different species of Glycyrrhiza. At the same time, the alcohol precipitation treatment process affects the structure of the extracted Glycyrrhiza polysaccharide. The research of the present invention finds that red-skinned licorice (Glycyrrhiza uralensis Fisch.) is selected for water extraction and alcohol precipitation, and Glycyrrhiza polysaccharide with a new structure can be obtained under the above alcohol precipitation treatment parameters.

[0011] Animal experiments in vivo show that the Glycyrrhiza polysaccharide extracted by the present invention has biological activities such as improving lung function, reducing lung tissue damage, enhancing antioxidant capacity, and regulating the intestinal microbial community.

[0012] In a second aspect, a Glycyrrhiza polysaccharide is obtained by the above preparation method.

[0013] In a third aspect, a pharmaceutical composition includes the above Glycyrrhiza polysaccharide and a pharmaceutical excipient.

[0014] In a fourth aspect, an application of the above Glycyrrhiza polysaccharide or pharmaceutical composition in the preparation of a drug for treating acute lung injury is provided.

[0015] In a fifth aspect, an application of the above Glycyrrhiza polysaccharide or pharmaceutical composition in the preparation of an antioxidant and / or anti-inflammatory drug is provided.

[0016] In a sixth aspect, an application of the above Glycyrrhiza polysaccharide or pharmaceutical composition in the preparation of a product for regulating the intestinal flora is provided.

[0017] According to the present invention, the concept of "treatment" means any measure applicable to improving or repairing symptoms related to acute lung injury, or treating the existing acute lung injury, or preventing the recurrence of the disease, such as preventing the recurrence of acute lung injury after treatment or treating the symptoms that have already occurred.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The extraction method of Glycyrrhiza polysaccharide provided by the present invention successfully extracts a new type of Glycyrrhiza polysaccharide with biological activity from red-skinned licorice through the selection of Glycyrrhiza species and the improvement of the alcohol precipitation process.

[0020] (2) The protective effect of the Glycyrrhiza polysaccharide extracted by the present invention in acute lung injury in mice. Specifically, the effectiveness of Glycyrrhiza polysaccharide is verified through a mouse acute lung injury model in in vivo experiments. The results show that Glycyrrhiza polysaccharide can significantly reduce lung tissue damage, improve lung function, and protect lung epithelial cells.

[0021] (3) The antioxidant and anti-inflammatory effects of the glycyrrhizin polysaccharide extracted by the present invention are manifested as reducing oxidative stress indicators, enhancing the activity of antioxidant enzymes, and alleviating apoptosis. The levels of inflammatory factors TNF-α, IL-6, and IL-1β are significantly reduced, thereby effectively alleviating the inflammatory response and protecting the health of lung tissue.

[0022] (4) The regulatory effect of the glycyrrhizin polysaccharide extracted by the present invention on the intestinal flora is specifically manifested as improving the abundance and diversity of the intestinal flora, which helps to restore the balance of the intestinal microecosystem.

[0023] (5) The glycyrrhizin polysaccharide extracted by the present invention has wide applications, is easy to obtain, safe, has universality, and is easy to scale up production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0025] Figure 1 It is the Fourier transform infrared spectrum diagram of the glycyrrhizin polysaccharide prepared in Example 1 of the present invention;

[0026] Figure 2 It is the total ion current diagram of the methylation product of the glycyrrhizin polysaccharide prepared in Example 1 of the present invention;

[0027] Figure 3 It is the structural analysis result diagram of the glycyrrhizin polysaccharide prepared in Example 1 of the present invention;

[0028] Figure 4 It is the result diagram of the anti-inflammatory effect of the glycyrrhizin polysaccharide prepared in Example 1 of the present invention on the acute lung injury model of mice; A is the ratio of lung wet weight to dry weight, B is the pathological score of lung tissue injury, C is the pathological section of lung tissue of each group of mice, D is the level of IL-1β in bronchoalveolar lavage fluid, E is the level of IL-6 in bronchoalveolar lavage fluid, F is the level of TNF-α in bronchoalveolar lavage fluid, G is the level of IL-1β in serum, H is the level of IL-6 in serum, and I is the level of TNF-α in serum.

[0029] Figure 5 It is the result diagram of the antioxidant effect of the glycyrrhizin polysaccharide prepared in Example 1 of the present invention on the acute lung injury model of mice; A is the level of GSH in lung tissue, B is the level of T-AOC in lung tissue, C is the level of CAT in lung tissue, D is the level of SOD in lung tissue, E is the level of MDA in lung tissue, F is the level of GSH-PX in lung tissue, G is the level of GSH in serum, H is the level of T-AOC in serum, I is the level of CAT in serum, J is the level of SOD in serum, K is the level of MDA in serum, and L is the level of GSH-PX in serum.

[0030] Figure 6 Results of the effect of glycyrrhizin polysaccharide prepared in Example 1 of the present invention on the expression of tight junction proteins in lung tissue; A is the immunohistochemical section of lung tight junction proteins ZO-1 and Occludin in each group, B is the quantification of ZO-1 expression, and C is the quantification of ZO-1 expression.

[0031] Figure 7 Results of the effect of glycyrrhizin polysaccharide prepared in Example 1 of the present invention on the abundance and diversity of intestinal microorganisms; A is the Venn diagram analysis of species, B is the PCoA analysis, C is the NMDS analysis, D is the community composition distribution at the Genus level, E is the community composition distribution at the Family level, F is the community composition distribution at the Phylum level, and G is the community composition heatmap. Detailed implementation mode

[0032] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0033] It should be noted that the terms used herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes according to the present invention. As used herein, unless otherwise clearly specified in the context, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] In order to avoid the defects of large toxic and side effects and limited therapeutic effects existing in existing antibiotics or steroid drugs, the present invention provides a glycyrrhizin polysaccharide, a preparation method thereof, and an application thereof in the preparation of a drug for treating acute lung injury.

[0035] A typical implementation mode of the present invention provides a preparation method of the above-mentioned glycyrrhizin polysaccharide, which includes the following steps:

[0036] Add water to red-skinned licorice and boil it for extraction to obtain an aqueous extract;

[0037] Add an alcohol solution with a volume concentration of 70-75% to the aqueous extract for alcohol precipitation, and the volume ratio of the aqueous extract to the alcohol solution is 1.20-1.30:1.

[0038] In some embodiments, the red-skinned licorice is decolorized with absolute ethanol and then added with water and boiled for extraction.

[0039] In some embodiments, during the extraction process, the solid-liquid ratio of red-skinned licorice to water is 1:5-10, kg / L; preferably 1:5.5-6.5.

[0040] In some embodiments, during the extraction process, the boiling treatment time is 1 to 3 hours, preferably 1.8 to 2.2 hours.

[0041] In some embodiments, during the extraction process, the number of times of boiling with added water is 1 to 5 times, preferably 3 times. Specifically, after boiling with added water for 1 to 3 hours, solid-liquid separation is performed, and the separated medicinal residues are continued to be boiled with added water. After repeating at least 1 time, the liquids are combined to obtain the water extract.

[0042] In some embodiments, the time for alcohol precipitation treatment is 10 to 40 hours, preferably 22 to 26 hours.

[0043] The third embodiment of the present invention provides a pharmaceutical composition, including the above-mentioned glycyrrhizin polysaccharide and pharmaceutical excipients.

[0044] In some embodiments, the pharmaceutical excipients include, but are not limited to, binders, fillers, lubricants, stabilizers, antioxidants, pH regulators, preservatives, flavoring agents, fragrances, etc.

[0045] Another embodiment of the present invention provides a glycyrrhizin polysaccharide obtained by the above preparation method.

[0046] The fourth embodiment of the present invention provides an application of the above-mentioned glycyrrhizin polysaccharide or pharmaceutical composition in the preparation of a drug for treating acute lung injury.

[0047] The drug of the present invention can be administered in unit dosage form, and the dosage form can be a liquid dosage form or a solid dosage form. The liquid dosage form can be a true solution, colloid, particulate dosage form, emulsion or suspension. Other dosage forms such as tablets, capsules, dripping pills, aerosols, pills, powders, solution agents, emulsions, granules, suppositories, freeze-dried powder injections, inclusion compounds, landfill agents, patches and liniments, etc.

[0048] In some embodiments, the administration object of the drug is a human or a non-human animal. The non-human animal can be a mouse, rat, dog, rabbit, monkey, etc.

[0049] In some embodiments, the acute lung injury is mediated by oxidative stress and / or inflammatory response.

[0050] In some embodiments, the drug is used to protect the pulmonary tissue epithelial barrier of patients with acute lung injury; and / or, to enhance the antioxidant capacity and / or anti-inflammatory capacity of patients with acute lung injury; and / or, to regulate the intestinal flora of patients with acute lung injury.

[0051] Specifically, the protection of the epithelial barrier of lung tissue is manifested as follows: Glycyrrhiza polysaccharide can significantly reduce the pathological damage of lung tissue, improve the alveolar structure, and increase the expression of tight junction proteins (such as ZO-1, Occludin). Glycyrrhiza polysaccharide has a better protective effect in the high-dose group compared with the low-dose group.

[0052] Specifically, the antioxidant effect is manifested as follows: Glycyrrhiza polysaccharide can significantly improve the antioxidant indexes in mice, including but not limited to:

[0053] Catalase (CAT): Glycyrrhiza polysaccharide can significantly increase the activity of CAT, promote the decomposition of hydrogen peroxide, and reduce oxidative damage.

[0054] Malondialdehyde (MDA): Glycyrrhiza polysaccharide can effectively reduce the level of MDA and reduce the degree of lipid peroxidation of cell membranes.

[0055] Glutathione (GSH): Glycyrrhiza polysaccharide can increase the content of GSH in the body and provide important antioxidant protection for cells.

[0056] Glutathione peroxidase (GSH-PX): Glycyrrhiza polysaccharide can increase the activity of GSH-PX, thereby enhancing the cell's resistance to oxidative stress.

[0057] Total antioxidant capacity (TAOC): Glycyrrhiza polysaccharide can improve the total antioxidant capacity and enhance the body's own resistance to oxidative damage.

[0058] Specifically, the anti-inflammatory effect is manifested as follows:

[0059] TNF-α: Glycyrrhiza polysaccharide can significantly reduce the level of TNF-α in mice, indicating its good anti-inflammatory effect, thus inhibiting the enhancement of the inflammatory response.

[0060] IL-6: The level of IL-6 in mice treated with Glycyrrhiza polysaccharide is significantly reduced, indicating that Glycyrrhiza polysaccharide can effectively reduce the release of cytokines caused by inflammation and further reduce the inflammatory damage of lung tissue.

[0061] IL-1β: Glycyrrhiza polysaccharide can significantly inhibit the production of IL-1β, suggesting that it plays an important role in regulating the immune response and may reduce the tissue damage caused by acute pneumonia by reducing the release of inflammatory factors.

[0062] Specifically, the effect of regulating intestinal flora is manifested as follows: In the acute lung injury model, Glycyrrhiza polysaccharide can improve the abundance of intestinal flora, significantly increase the abundance of beneficial flora, and at the same time reduce the proportion of harmful flora. The effect of Glycyrrhiza polysaccharide can restore the intestinal microecological balance, thereby indirectly improving lung injury.

[0063] The fifth embodiment of the present invention provides an application of the above-mentioned glycyrrhizin polysaccharide or pharmaceutical composition in the preparation of antioxidant and / or anti-inflammatory drugs.

[0064] The sixth embodiment of the present invention provides an application of the above-mentioned glycyrrhizin polysaccharide or pharmaceutical composition in the preparation of products for regulating intestinal flora.

[0065] The products described in the present invention include but are not limited to foods and drugs. The foods can be understood in any edible form. For example, the foods in the present invention include ordinary foods and special foods, and the special foods include health foods and foods for special medical purposes; while ordinary foods are foods suitable for everyone.

[0066] The present invention also provides a method for preventing and treating acute lung injury, which includes administering the above-mentioned glycyrrhizin polysaccharide or pharmaceutical composition to a subject.

[0067] In order to enable those skilled in the art to more clearly understand the technical solutions of the present invention, the following will specifically describe the technical solutions of the present invention in detail with reference to examples and comparative examples.

[0068] Example 1: Preparation of glycyrrhizin polysaccharide

[0069] The glycyrrhizin polysaccharide was prepared through the following steps:

[0070] S1. The red-skinned licorice (produced in Gansu) samples dried at 50°C were sliced into licorice slices.

[0071] S2. The licorice slices obtained in step S1 were subjected to decolorization treatment with anhydrous ethanol. 300 g of glycyrrhizin polysaccharide was heated in a water bath at 60°C, and condensed and refluxed with 95% ethanol in a round-bottom flask, repeated 2 - 3 times, each time for 2 - 4 hours. After taking out the medicinal residues and drying them for 12 hours, water was added and boiled for extraction treatment; during the extraction treatment process, the number of times of boiling with water added was 3 times, the material-liquid ratio of each time of boiling with water added was 1:6 (kg / L), the boiling treatment time was 2 hours, the filtrate and filter residues were obtained by filtration, the filter residues were used for the next boiling with water added, and finally the filtrates were combined to obtain the water extract.

[0072] S3. The water extract obtained in step S2 was subjected to alcohol precipitation treatment. Specifically, 75% ethanol was added to the water extract (the volume ratio of the water extract to 75% ethanol was 5:4), and the precipitate was collected after standing for 24 hours, and freeze-dried to obtain glycyrrhizin polysaccharide (GCPE2F). Fourier transform infrared spectroscopy (FT-IR) verified that GCPE2F had a typical polysaccharide structure, as Figure 1 shown. It should be noted that compared with the crude polysaccharide, GCPE2F had absorption peaks at 1371 cm -1 and 1147 cm -1The peak intensity at [location] increased, indicating that the monosaccharide composition or structure might have been optimized after purification. This structural feature is of great significance as it may facilitate interactions with immune receptors, similar to β-glucan and its immunomodulatory properties.

[0073] As shown in the total ion chromatogram of the methylation products and their analysis results, GCPE2F includes 24 types of glycosidic bond linkages, among which the 1,4-GalpA residue dominates, accounting for approximately 62.500%. In addition, there are 1,3-Glcp and other minor glycosidic bonds present, indicating the complex linkage structure of GCPE2F. It can be seen that the backbone of GCPE2F is mainly composed of 1,4-galacturonic acid (GalA) and 1,4-glucose (Glc) linked by glycosidic bonds, and the 1,3-linked sugar residues form branches at different positions, showing the diversity and possible biological functions of this polysaccharide.

[0074] The glycyrrhiza polysaccharide prepared in this example was used in Examples 2 - 5.

[0075] Example 2: Anti-inflammatory effect of glycyrrhiza polysaccharide

[0076] Specifically, to explore the effect of glycyrrhiza polysaccharide on improving acute lung injury in mice, 60 C57BL / 6 mice aged 6 - 8 weeks (about 20 ± 2 g) were purchased and randomly divided into 4 groups, namely the control group (C), the model group (M), the low-dose glycyrrhiza polysaccharide group (L), and the high-dose glycyrrhiza polysaccharide group (H). The high-dose polysaccharide group (H) and the low-dose polysaccharide group (L) were intragastrically administered glycyrrhiza polysaccharide at doses of 60 and 30 mg / kg respectively, while the control group and the model group were intragastrically administered an equal volume of normal saline. After 12 days of feeding, the mice in the model group (M), the high-dose polysaccharide group (H), and the low-dose polysaccharide group (L) were anesthetized with ether and given 5 mg / kg LPS intranasally for 12 h to establish an acute lung injury model, and the control group was instilled with an equal volume of double-distilled water into the nasal cavity. 12 h after LPS administration, the mice were sacrificed, and relevant samples such as serum, lung tissue, and bronchoalveolar lavage fluid were collected respectively. After sampling, the samples were applicable to Examples 1 - 4. The levels of inflammatory factors TNF-α, IL-6, and IL-1β in the bronchoalveolar lavage fluid and serum were analyzed. The number of positive cells per high-power field was calculated. The results showed that glycyrrhiza polysaccharide could significantly improve the antioxidant indexes in mice and alleviate acute lung injury in mice caused by oxidative stress, as Figure 4 shown.

[0077] Example 3: Antioxidant effect of glycyrrhiza polysaccharide

[0078] Experimental method, animal model: The same as in Example 2.

[0079] Analyze the levels of MDA, GSH, GSH-PX, CAT, T-AOC, and SOD in bronchoalveolar lavage fluid and serum. The results showed that glycyrrhizin polysaccharide could significantly improve the antioxidant indexes in mice and ameliorate acute lung injury in mice caused by oxidative stress, as Figure 5 shown.

[0080] Example 4: Barrier protection effect of glycyrrhizin polysaccharide

[0081] Experimental method, animal model: The same as Example 2.

[0082] Collect lung tissues and store them in 4% paraformaldehyde fixative for more than 48 h. Dehydrate the fixed tissues step by step and embed them in paraffin. After dewaxing, hydration, and antigen repair of 4-μm paraffin sections of lung tissues, immunohistochemical staining was used to detect the expression of the following proteins: ZO-1 (1:200; rabbit monoclonal antibody, #ab221547, Abcam, UK); Occludin (1:200; rabbit polyclonal antibody, #27260-1-AP, Proteintech, China). The immunohistochemical results showed that glycyrrhizin polysaccharide could enhance the tight protein connectivity in lung tissues of mice with LPS-induced acute lung injury, and the high-dose group had a better effect than the other groups, as Figure 6 shown.

[0083] Example 5: Glycyrrhizin polysaccharide can improve LPS-induced intestinal microbiota disorder in mice

[0084] Experimental method, animal model: The same as Example 2.

[0085] 16S rRNA sequencing was performed on mouse colon feces, and PCR amplification was carried out based on the V3-V4 region of the 16S rRNA gene. The reaction system (25 μL) contained TransStart Fastpfu DNA Polymerase (TransGen Biotech, Beijing), 10 μM primers, and template DNA. The amplification program was as follows: pre-denaturation at 95 °C for 5 min; 30 s at 95 °C, 30 s at 55 °C, and 40 s at 72 °C for a total of 28 cycles; extension at 72 °C for 10 min. After verification by 2% agarose gel electrophoresis, the amplification products were normalized using the Quantifluor TM -ST blue fluorescence quantification system (Promega) and a PE300 library (TruSeq TM DNA Sample Prep Kit) was constructed and paired-end sequencing was performed on the Nextseq2000 platform (Illumina).

[0086] After the raw data were spliced and quality controlled, Uparse software (v7.0.1090) was used to perform OTU clustering with 97% similarity, and singletons were removed. The representative sequences of OTUs were annotated for species by aligning them with the SILVA (Release 138), RDP (Release 11.5), and Greengenes (Release 13.5) databases using RDP Classifier (v2.11) (confidence threshold 0.7). Alpha diversity analysis was performed by calculating the Shannon, Simpson, Chao1, and ACE indices using Mothur (v1.30.2); Beta diversity analysis was based on the Bray-Curtis distance matrix, and principal coordinate analysis (PCoA) and non-metric multidimensional scaling analysis (NMDS) were used to evaluate the differences between groups, and the significance of grouping was verified by ANOSIM / Adonis test (999 permutations). The microbial community composition was visualized using R language (vegan package), including community Score>2.0, P<0.05) was used to screen for differentially abundant species between groups.

[0087] The sequencing results showed that the Venn diagram indicated that the treatment group and the control group shared core microbiota, but there were differences in specific microbiota, suggesting that glycyrrhizin polysaccharide played a role by regulating specific microbiota rather than comprehensively remodeling the microbiota. PCoA and NMDS analyses showed that glycyrrhizin polysaccharide significantly changed the intestinal microbiota structure of pneumonia mice, indicating that its regulatory effect was statistically significant. At the phylum level, the ratio of Bacteroidota to Firmicutes changed, which might affect host metabolism and immune balance. At the genus / family level, the abundances of beneficial bacteria such as Lactobacillus were significantly increased, promoting the recovery of the intestinal microecosystem. Glycyrrhizin polysaccharide reduced the abundances of pathogenic bacteria such as Escherichia-Shigella, alleviating intestinal inflammation, as Figure 7 shown.

[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing liquorice polysaccharide, characterized in that: The steps include: Adding water to red-skinned licorice and boiling it for extraction to obtain a water extract; An alcohol solution with a volume concentration of 70-75% is added to the water extract to perform alcohol precipitation treatment, and the volume ratio of the water extract to the alcohol solution is 1.20-1.30:

1.

2. The preparation method according to claim 1, characterized in that: Red licorice is decolorized with anhydrous ethanol and then boiled with water for extraction; Or, during the extraction process, the solid-liquid ratio of red licorice to water is 1:5-10, kg / L; preferably 1:5.5-6.5, kg / L; Or, during the extraction process, the boiling time is 1 to 3 hours, preferably 1.8 to 2.2 hours; Alternatively, during the extraction process, water is added and boiled 1 to 5 times.

3. The preparation method according to claim 1, characterized in that: The alcohol precipitation treatment time is 10 to 40 hours, preferably 22 to 26 hours.

4. A liquorice polysaccharide obtained by the preparation method according to any one of claims 1 to 3.

5. A pharmaceutical composition, characterized in that: The invention comprises the licorice polysaccharide as claimed in claim 4, and pharmaceutical excipients.

6. The pharmaceutical composition according to claim 5, characterized in that: The pharmaceutical excipients include one or more of a binder, a filler, a lubricant, a stabilizer, an antioxidant, a pH adjuster, a preservative, a flavoring agent, and a flavor.

7. Use of the glycyrrhiza polysaccharide according to claim 4 or the pharmaceutical composition according to claim 5 or 6 in the preparation of a drug for treating acute lung injury.

8. The use according to claim 7, characterized in that: The drug is administered to a human or non-human animal; Or, the acute lung injury is mediated by oxidative stress and / or inflammatory response; Alternatively, the drug is used to protect the epithelial barrier of lung tissue in patients with acute lung injury; and / or, to enhance the antioxidant capacity and / or anti-inflammatory capacity of patients with acute lung injury; and / or, to regulate the intestinal flora of patients with acute lung injury.

9. Use of the glycyrrhiza polysaccharide according to claim 4 or the pharmaceutical composition according to claim 5 or 6 in the preparation of antioxidant and / or anti-inflammatory drugs.

10. Use of the glycyrrhiza polysaccharide according to claim 4 or the pharmaceutical composition according to claim 5 or 6 in preparing a product for regulating intestinal flora.

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