Cogongrass rhizome polysaccharide for reducing uric acid as well as preparation method and application of cogongrass rhizome polysaccharide

Abstract

The invention relates to lalang grass rhizome polysaccharide for reducing uric acid as well as a preparation method and application thereof, and relates to the field of medicines. By reducing the activity of xanthine oxidase, increasing the expression of OAT1 and OAT3 proteins in the kidney, regulating and controlling the activity of antioxidant enzymes in the body, inhibiting the release of inflammatory factors, inhibiting the generation of uric acid and reducing the level of serum uric acid, the lalang grass rhizome polysaccharide has a good treatment effect on hyperuricemia and can effectively delay the renal lesion process.

Description

Technical Field

[0001] The invention relates to the field of medicines, and in particular to Imperata cylindrica polysaccharide for reducing uric acid, and a preparation method and application thereof. Background Art

[0002] Since the beginning of the new century, along with the continuous improvement of my country's social and economic level, diet has become more and more diversified. However, with the increase in the intake of foods with high fat and purine content, the incidence of many diseases has also increased, and hyperuricemia is such a situation. Hyperuricemia (HUA) is a common metabolic disease, and the most common cause is insufficient excretion and (or) excessive secretion of uric acid (UA). In recent years, the incidence of hyperuricemia in my country has shown a significant upward trend and tends to be younger. The overall prevalence of hyperuricemia in China is 13.3%, and gout is 1.1%, which has become the "fourth highest" after diabetes, hypertension, and hyperlipidemia. Gout is closely related to hyperuricemia caused by reduced uric acid excretion and (or) purine metabolism disorders. It is a crystal-related arthritis caused by excessive urate crystals deposited in and around the joints. Gout is divided into primary gout and secondary gout. Among them, primary gout is the most common, which is mainly caused by uric acid excretion disorders and / or congenital purine metabolism abnormalities in the absence of other diseases; while secondary gout is caused by increased uric acid production due to kidney disease, metabolic diseases, malignant tumors and drugs, or uric acid has antioxidant properties and can remove oxygen free radicals produced by oxidative stress to prevent aging. However, when uric acid is higher than normal, it will cause endothelial cell damage and induce the production of inflammatory factors, thereby causing a series of diseases such as nephrotic syndrome and metabolic disease syndrome. Therefore, the prevention and treatment of hyperuricemia is still the focus and hot spot of current clinical and scientific research work.

[0003] UA, also known as 2,6,8-trihydroxypurine, is a heterocyclic carbonyl compound with a relative molecular weight of 168. UA is a powerful active oxygen and peroxynitrite scavenger and antioxidant, weakly acidic, with a pKa of about 5.35 in urine and a pKa of about 5.8 in blood. It mainly exists in the physiological blood with a pH of 7.40 as uric acid anion. UA is mainly synthesized in the liver, intestines and other tissues, and is the final product of exogenous purines from animals. Living cells can also degrade their nucleic acids, adenine and guanine into uric acid. Its synthesis process is: 1. Guanine and adenine are converted into inosine and guanosine through deamination and dephosphorylation; 2. Guanosine and inosine are converted into hypoguanine and xanthine respectively by purine nucleoside phosphorylase; 3. Guanine and hypoxanthine are converted into xanthine by xanthine oxidase; 4. Xanthine is further catalyzed into uric acid by xanthine oxidase. Normally, the synthesis and excretion of UA are in a dynamic balance, and 75% of uric acid is excreted through the kidneys, and the remaining 25% or so is metabolized by intestinal bacteria after entering the intestines. This process is called intestinal uricosuric acid. Most of the urate is free and constantly circulates in the body, with a protein binding rate of less than 5%, so most of the urate is filtered by the glomerulus, but up to 90% of the urate may be reabsorbed later. Various urate transporters play a role in tubular reabsorption and urate secretion, helping to regulate the balance of uric acid in the body, thereby maintaining UA levels within a certain range. The kidney is the main excretion organ of uric acid, and the human body produces about 800 mg of uric acid every day. Therefore, the kidney plays a very important role in excreting uric acid in the body and maintaining the balance of uric acid metabolism in the body. The process mainly involves glomerular filtration and tubular reabsorption. An important reason for high uric acid levels is the insufficient renal excretion capacity of urate, which is regulated and controlled by multiple transporters. For example, important transporters for uric acid excretion are organic anion transporters including URAT1, OAT1, OAT3 and OAT4. OAT1 and OAT3 transfer uric acid from the blood to the renal tubules, and then reabsorb it into the renal tubular cells through URAT1 and OAT4 in exchange for dicarboxylic acid. When uric acid breaks the balance, excessive production or reduced excretion will lead to the occurrence of hyperuricemia. Referring to the current international standards, my country defines hyperuricemia as a blood uric acid level of more than 420 μmol / L on two different days for both men and women under a normal purine diet.

[0004] At present, hyperuricemia is divided into three categories according to the generation and excretion of uric acid in the blood: excessive uric acid synthesis type, poor uric acid excretion type and mixed type. Clinical treatment mainly uses drugs to reduce the patient's blood uric acid level, inhibit blood uric acid synthesis, promote blood uric acid dissolution, and promote blood uric acid excretion, thereby reducing organ function damage, while inhibiting bone and joint urate deposition to prevent the occurrence of gout. Febuxostat belongs to the non-purine drug class, which can inhibit the reduction and oxidation of xanthine oxidase. It is a xanthine oxidase inhibitor and will not have a significant effect on the body's purine and pyrimidine metabolism. Long-term use has no serious adverse reactions. It is metabolized by the liver and excreted through feces. It has no serious renal toxicity and is highly safe. The main function of Febuxostat is to reduce blood uric acid levels and improve the clinical symptoms of patients with hyperuricemia. Colchicine is still the first-line drug for acute gout attacks, but long-term and large-scale use of the drug has the risk of renal insufficiency and certain risks. Summary of the invention

[0005] In view of the above problems, the present invention provides an application of Imperata cylindrica root polysaccharide for lowering uric acid in the preparation of a uric acid-lowering drug. The Imperata cylindrica root polysaccharide reduces the activity of xanthine oxidase, increases the expression of OAT1 and OAT3 proteins in the kidney, regulates the activity of antioxidant enzymes in the body, inhibits the release of inflammatory factors, inhibits uric acid production, and reduces serum uric acid levels. It has a good therapeutic effect on hyperuricemia and can effectively delay the progression of kidney disease.

[0006] In order to achieve the above-mentioned purpose, the present invention provides an application of Imperata cylindrica root polysaccharide for lowering uric acid in the preparation of uric acid lowering drugs. The preparation method of Imperata cylindrica root polysaccharide comprises: obtaining Imperata cylindrica root total polysaccharide by water extraction and alcohol precipitation method, separating Imperata cylindrica root polysaccharide components by anion exchanger, and purifying to obtain Imperata cylindrica root polysaccharide.

[0007] Imperata root, also known as Ru root, ground tendon, Imperata sedge, silk grass, and thatch root, is the dried rhizome of Imperata cylindrical Beauv. var. major (Nees) CE Hubb., a plant of the genus Imperata in the Gramineae family. Figure 1As shown, it is a perennial rhizome plant that can grow on soil with a lot of nutrients, water and a moderate pH value. It is widely distributed in the Indian continent, tropical and subtropical Africa, Southeast Asia and Australia. There are about 10 species of Imperata root worldwide, 4 of which are distributed in China. It can grow up to 1.2 meters high, with narrow and hard leaves, beards at the base and hairless on the upper part. Imperata root generally matures in spring and autumn. After digging it out, the above-ground part and the scaly leaf sheaths are removed, washed, and used fresh or tied into bundles to dry. There are two specifications of Imperata root slices, namely Imperata root and Imperata root charcoal. It tastes sweet and is cold in nature. It has the effects of cooling blood and stopping bleeding, clearing heat and promoting diuresis. It is used to treat fever, thirst, damp-heat jaundice, edema, oliguria, hot stranguria, and blood heat, vomiting blood, epistaxis, and hematuria. Later generations of doctors recorded its clinical application in detail in classic works of traditional Chinese medicine such as "Famous Doctors' Records", "Emergency Prescriptions for the Elbow", "Qianjin Yifang", "Compendium of Materia Medica", and "Medical Records of Zhongzhong Canxi". So far, there are more than 100 main active ingredients in Imperata cylindrica root that have been recorded. Modern research has found that the active ingredients in Imperata cylindrica root have a wide range of pharmacological activities in anti-oxidation, anti-inflammatory, anti-tumor, immune function regulation, hemostasis, etc., and show good therapeutic effects in the treatment of malignant tumors, chronic hepatitis, chronic nephritis and other diseases. In addition, the aerial part of Imperata cylindrica root is rich in Ca 2+ 、Na + Mg 2+ , Fe 3+ and K + Imperata root contains trace elements such as iodine, iodine, and sulphur. It can survive in seawater salt concentrations and has high nutritional potential. Imperata root is a food and medicine product, but its modern processed products are rare. In traditional Chinese medicine, Imperata root is used to treat bleeding, improve urination and immunomodulation, and is also used to treat inflammation and fever in Korea. Since Imperata root sugars can reach about 80% of the extract, in the present invention, the separation and purification of Imperata root polysaccharides are mainly carried out, and its uric acid-lowering effect is evaluated, and its uric acid-lowering mechanism and effective approach are preliminarily explored. Through animal experiments, it was found that the Imperata root polysaccharide reduces the activity of xanthine oxidase, increases the expression of OAT1 and OAT3 proteins in the kidney, regulates the activity of antioxidant enzymes in the body, inhibits the release of inflammatory factors, inhibits uric acid production, and reduces serum uric acid levels. It has a good therapeutic effect on hyperuricemia and can effectively delay the progression of kidney disease.

[0008] In one embodiment, the Imperata root polysaccharide component is an acidic sugar, and the preparation method of the Imperata root polysaccharide component comprises the following steps: the total polysaccharide of Imperata root is separated by an anion exchanger to obtain an eluate, the eluate is eluted with water until there is no polysaccharide absorption under ultraviolet light, and eluted with 0.15-0.25 mol / mL NaCl solution to obtain the Imperata root polysaccharide component.

[0009] In one embodiment, the drug further comprises a pharmaceutically acceptable excipient.

[0010] In one embodiment, the drug reduces the activity of XOD, increases the expression of OAT1 and OAT3 proteins in the kidney, inhibits uric acid production, and reduces serum uric acid levels.

[0011] In one embodiment, the drug is in the form of oral solution, pills, granules, capsules, tablets, pellets, injections or powders.

[0012] In one embodiment, the dosage of Imperata cylindrica polysaccharide is 35-90 mg / kg / d.

[0013] In one embodiment, the dosage of Imperata cylindrica polysaccharide is 35-60 mg / kg / d.

[0014] In one embodiment, the dosage of Imperata cylindrica polysaccharide is 60-90 mg / kg / d.

[0015] The present invention also provides a method for preparing Imperata cylindrica root polysaccharide in the application, comprising the following steps: extracting Imperata cylindrica root by water and ethanol precipitation to obtain Imperata cylindrica root total polysaccharide, separating Imperata cylindrica root polysaccharide components by anion exchanger, and purifying to obtain Imperata cylindrica root polysaccharide.

[0016] In one embodiment, the anion exchanger comprises DEAE cellulose.

[0017] In one embodiment, the purification includes: using agarose gel to separate and purify the Imperata cylindrica polysaccharide component, and using 0.1-0.2 mol / mL NaCl solution as the elution mobile phase for elution.

[0018] In one embodiment, during the purification, the flow rate of the elution mobile phase is 0.3-0.5 mL / min.

[0019] In one embodiment, the agarose gel comprises agarose gel CL-4B.

[0020] In one embodiment, the water extraction and alcohol precipitation method includes: adding ethanol to the Imperata root for reflux degreasing to obtain the residue, adding water for reflux extraction, combining the filtrate, filtering, taking the filtrate, concentrating, adding ethanol, standing for alcohol precipitation, removing the precipitate, washing, and drying to obtain the Imperata root total polysaccharide.

[0021] In one embodiment, the temperature of the standing alcohol precipitation is 3-5°C and the time is 45-50h.

[0022] In one embodiment, the reflux extraction conditions include: extraction temperature of 75-105°C, extraction time of 1.5-4.5h, extraction times of 3-5 times, and solid-liquid ratio of 1:(8-12).

[0023] The present invention also provides a uric acid-lowering drug, comprising a drug active ingredient and a pharmaceutically acceptable excipient, wherein the drug active ingredient comprises the Imperata cylindrica polysaccharide used in the application.

[0024] In one embodiment, the active pharmaceutical ingredient further comprises an ingredient compatible with Imperata cylindrica polysaccharide.

[0025] The invention also provides Imperata cylindrica polysaccharide obtained by the preparation method.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention discloses a Imperata root polysaccharide for reducing uric acid, and a preparation method and application thereof. The Imperata root polysaccharide can reduce the activity of xanthine oxidase, increase the expression of OAT1 and OAT3 proteins in the kidney, regulate the activity of antioxidant enzymes in the body, inhibit the release of inflammatory factors, inhibit the production of uric acid, and reduce the serum uric acid level. It has a good therapeutic effect on hyperuricemia and can effectively delay the progression of kidney disease. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of Imperata cylindrica;

[0029] Figure 2 This is the elution curve of Imperata cylindrica polysaccharide on DEAE cellulose column chromatography in the embodiment;

[0030] Figure 3 The elution curve of ICPB on Sepharose CL-4B gel chromatography column in the embodiment;

[0031] Figure 4 The molecular weight determination results of ICPA, ICPB and ICPC in the embodiment are shown in FIG. 1 , wherein from top to bottom are the molecular weight determination results of ICPA, the molecular weight determination results of ICPB and the molecular weight determination results of ICPC;

[0032] Figure 5 The molecular weight measurement results of ICPB-b, ICPB-c and ICPB-d in the examples are shown in FIG. 1 , wherein from top to bottom are the molecular weight measurement results of ICPB-b, the molecular weight measurement results of ICPB-c and the molecular weight measurement results of ICPB-d;

[0033] Figure 6This is a comparison of the scavenging effects of ICP, ICPA, ICPB, ICPC, and ICPC-d on DPPH in the examples;

[0034] Figure 7 This is a comparison diagram of the scavenging effects of ICP, ICPA, ICPB, ICPC and ICPB-d on hydroxyl radicals in the examples;

[0035] Figure 8 The results of the changes in serum UA, CAT, IL-1β, and TNF-a levels in mice in the example are compared with those in the CON group. ## p<0.01, compared with Mod group, *p<0.05, **p<0.01;

[0036] Fig. 9 The results of the changes in the MDA and T-SOD contents in the kidney tissue of mice in the example are compared with the CON group. ## p<0.01, compared with Mod group, *p<0.05, **p<0.01;

[0037] Fig.10 The changes of XOD content in the liver tissue of mice in the example are compared with the CON group. ## p<0.01, compared with Mod group, *p<0.05, **p<0.01;

[0038] Fig.11 The light microscopic image of the kidney pathological morphology (200×) in the example;

[0039] Fig.12 The expression results of NF-κB, OAT1, and OTA3 proteins in the kidney tissue of mice in the example are compared with those in the CON group. ## p<0.01, compared with the Mod group, *p<0.05, **p<0.01. DETAILED DESCRIPTION

[0040] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0042] source:

[0043] Imperata root (Hebei Liankang Pharmaceutical Co., Ltd.), DEAE-cellulose (Yuanye Biotechnology), Sepharose CL-4B (Beijing Ruida Henghui Technology Development Co., Ltd.), sodium chloride (Beijing Chemical Plant), anhydrous ethanol (Tianjin Damao Chemical Reagent Factory), redistilled phenol (Beijing Dingguo Changsheng Biotechnology Co., Ltd.), concentrated sulfuric acid (Tianjin Kaixin Chemical Industry Co., Ltd.), glucose standard (Shanghai Hongrui Chemical Co., Ltd.), standard for monosaccharide composition determination (Sigma), analytical grade, chromatographic grade (Liaoning Quanrui Reagent Co., Ltd.), constant temperature water bath (Beijing Chang'an Scientific Instrument Factory), rotary evaporator (Shanghai Quanjie Instrument Co., Ltd.), high-speed centrifuge (eppendorf), ultraviolet spectrophotometer (Shimadzu International Trade Co., Ltd.), InfiniteM200 microplate reader (Swiss TECAN Group), digital display blast drying oven (Shanghai Huxi Analytical Instrument Factory), AL204 electronic balance (METTLER TOLEDO), water purifier (Milli-Q), uric acid kit (Nanjing Jiancheng Biological Research Institute), MDA, T-SOD, XOD, CAT kit (Nanjing Jiancheng Biological Research Institute), IL-1β ELISA kit (Langdun Biotechnology Co., Ltd.), TNF-a ELISA kit (Langdun Biotechnology Co., Ltd.), RIP lysis buffer (Beijing Dingguo Changsheng Biotechnology Co., Ltd.), Rainbow Marker (GE Healthcare, USA), primary antibody NF-kB, OAT1, OAT3 (ABclonal), HRP GoatAnti-Rabbit IgG (H+L) (ABclonal), ultrasensitive ECL chemiluminescence kit (Biyuntian), HE staining kit (Legen Biotechnology), BCA protein quantification reagent (Beijing Dingguo Changsheng Biotechnology Co., Ltd.), DPPH (TicA (Shanghai) Chemical Industry Co., Ltd.), ascorbic acid (VC) (Beijing Dingguo Changsheng Biotechnology Co., Ltd.), ferrous sulfate (Yongda Reagent), salicylic acid (Yongda Reagent), ThermoMixer C constant temperature oscillator (eppendorf), Infinite M200 microplate reader (TECAN Group, Switzerland), AL204 electronic balance (METTLER TOLEDO), low-temperature high-speed centrifuge (eppendorf), fully automatic fluorescence and chemiluminescence gel imager (Beijing Saizhi Venture Technology Co., Ltd.), 4°C refrigerator (Qingdao Haier Group), UV-2550 ultraviolet-visible spectrophotometer (Shimadzu International Trading Co., Ltd.).

[0044] Unless otherwise specified, the reagents, materials, and equipment used in this example are all commercially available; the experimental methods are all conventional experimental methods in the art unless otherwise specified.

[0045] Example

[0046] 1. Isolation, purification and structural analysis of Imperata cylindrica root polysaccharide.

[0047] 1. Experimental method.

[0048] 1.1 Orthogonal test for extracting Imperata cylindrica root polysaccharides.

[0049] After the dried Imperata root medicinal material is crushed, it is passed through a 10-mesh sieve. 100g of Imperata root powder is accurately weighed, and 8 times the amount of 95% ethanol is added for reflux degreasing twice, each time for 2 hours. The residue after ethanol extraction is dried to constant weight, and the residue is divided into 10 equal parts by weighing, that is, each part is equivalent to 10g of Imperata root medicinal material. Take 9 parts, add distilled water to reflux extraction according to the proportion, combine the filtrate, filter, remove the residue, and concentrate under reduced pressure to about 50mL. Add anhydrous ethanol to the concentrated filtrate so that the final ethanol volume fraction of the system is 80%, and let it stand at 4°C for 48h. Separate the precipitate, wash the obtained polysaccharide with anhydrous ethanol several times, and place it in a 60°C constant temperature water bath to dry to constant weight to obtain the total polysaccharide (ICP) of Imperata root. After preliminary experiments, the extraction temperature (A), extraction time (B), extraction times (C), and solid-liquid ratio (D) in the above reflux extraction step were finally determined as the final factors for investigation. Each factor was selected at 3 levels, and L9 (3 4 ) Orthogonal experimental design scheme, taking the percentage of total polysaccharides of Imperata cylindrica as the investigation index, to determine the optimal extraction conditions. The factor levels are shown in Table 1.

[0050] Table 1 Factor levels of orthogonal test of Imperata cylindrica

[0051]

[0052]

[0053] 1.2 Isolation and purification of Imperata cylindrica root polysaccharide.

[0054] Weigh an appropriate amount of total polysaccharide from Imperata root, dissolve it in distilled water to a concentration of 10 mg / mL, dialyze for 2-3 days to remove ash, change distilled water every 3 hours, and freeze-dry under reduced pressure to obtain refined polysaccharide from Imperata root. Weigh 1 g of refined polysaccharide from Imperata root and dissolve it in 20 mL of distilled water. Take the supernatant after centrifugation and use DEAE anion exchange column (1.5×60 cm, equilibrated with water-salt-water sequence before loading) for preliminary separation and purification. Collect the eluate in a test tube, set the flow rate to 1 mL / min, 8 mL per tube, elute with distilled water as the mobile phase for tubes 1-35, elute with 0.2 mol / mL NaCl solution for tubes 36-55, and elute with 0.5 mol / mL NaCl solution for tubes 56-80. After the eluate is appropriately diluted, the polysaccharide content is determined by the phenol-sulfuric acid method and a curve is drawn according to the absorption value. According to the elution curve, the eluate of the corresponding test tube is combined according to the elution peak, and the component eluted with distilled water is concentrated to a small volume and freeze-dried to obtain the neutral component of Imperata root polysaccharide (ICPA). The component eluted with two concentrations of NaCl solution is dialyzed to remove salt and then concentrated to a small volume and freeze-dried to obtain the acidic components of Imperata root polysaccharide ICPB and ICPC, wherein the polysaccharide eluted with 0.2 mol / mL NaCl solution is ICPB, and the polysaccharide eluted with 0.5 mol / mL NaCl solution is ICPC. It can be understood that if ICPB is prepared separately, the total polysaccharide of Imperata root is separated by an anion exchanger to obtain an eluate, the eluate is eluted with water until there is no polysaccharide absorption under ultraviolet light, and eluted with 0.2 mol / mL NaCl solution to obtain the acidic component of Imperata root polysaccharide ICPB.

[0055] Dissolve 300 mg of ICPB in 10 mL of distilled water, centrifuge and take the supernatant, and use Sepharose CL-4B column (2.6×100 cm) chromatography for further separation and purification. Use 0.15 mol / mL NaCl solution as the elution mobile phase, set the flow rate to 0.4 mL / min, 8 mL per tube. After the eluent is appropriately diluted, the polysaccharide content is determined by the phenol-sulfuric acid method and a curve is drawn according to the absorption value. According to the elution curve, the eluents of the corresponding test tubes are combined according to the elution peak, and after dialysis to remove salt, they are concentrated to a small volume and freeze-dried to obtain the purified components of Imperata root acid polysaccharide ICPB-a, ICPB-b, ICPB-c, and ICPB-d. In this embodiment, Imperata root polysaccharide ICPB-d is obtained after 20 tubes.

[0056] 1.3 Determination of molecular weight of Imperata cylindrica root polysaccharide.

[0057] Weigh 5 mg of sample accurately, add 1 mL of 0.05 M NaCl solution to the sample to prepare a 5 mg / mL test sample solution, centrifuge at 8000 rpm for 10 min, take the supernatant and filter it with a 0.22 μm microporous filter membrane, then place the sample in a 2 mL injection bottle for later use. HPGPC was used for analysis and determination, and dextran of different molecular weights was used for calibration to prepare a standard curve. The chromatographic column used three polymer-based water-soluble SEC (GFC) chromatographic columns (8×300 mm) connected in series. The chromatographic conditions were 0.05 M NaCl solution as the mobile phase, the flow rate was set to 0.65 mL / min, the column temperature was maintained at 40 ° C, the injection volume was 30 μL, and the detector was a Waters differential detector.

[0058] 2. Experimental results.

[0059] 2.1 Results of orthogonal experiment of total polysaccharides from Imperata root.

[0060] The defatted Imperata root was extracted with water, the filtrate was concentrated and then precipitated with alcohol, the precipitate was recovered by centrifugation and dried to constant weight, and the brown-yellow Imperata root total polysaccharide was obtained. The orthogonal test results were obtained by taking the percentage content of Imperata root total polysaccharide as an indicator, as shown in Table 2.

[0061] Table 2 Results of orthogonal test of Imperata cylindrica

[0062]

[0063]

[0064] As shown in Table 2, in factor A (extraction temperature), k2>k1>k3, in factor B (extraction time), k1>k2>k3, in factor C (number of extractions), k3>k1>k2, and in factor D (solid-liquid ratio), k1>k3>k2. According to the R value, B>D>A>C, that is, the order of influence of each factor on the total polysaccharide yield of Imperata cylindrica root is extraction time>solid-liquid ratio>extraction temperature>extraction number. Therefore, A1B1C3D1 was finally selected as the optimal extraction condition, that is, extraction temperature 80℃, extraction time 2h, extraction number 4 times, solid-liquid ratio m (sample, g) ∶ V (water, mL) 1:10.

[0065] 2.2 Results of ion exchange chromatography separation of Imperata root polysaccharides.

[0066] The total polysaccharide of Imperata cylindrica root was initially separated and purified by DEAE anion exchange column chromatography, and three components were obtained, namely, 115 mg of neutral sugar ICPA (yield 11.5%), 338 mg of two acidic sugars ICPB (yield 33.8%) and 277 mg of ICPC (yield 27.7%), see Figure 2 .

[0067] 2.3 Agarose gel chromatography separation results of Imperata root polysaccharide.

[0068] ICPB was further separated and purified using Sepharose CL-4B to obtain four elution peaks, namely ICPB-a 4 mg (yield 1.3%), ICPB-b 17.3 mg (yield 5.7%), ICPB-c 18.6 mg (yield 6.2%), and ICPB-d 163.3 mg (yield 54.4%). Figure 3 .

[0069] 2.4 Determination of molecular weight of Imperata root polysaccharide.

[0070] HPGPC was used to separate ICPA, ICPB and ICPC ( Figure 4 ), ICPB-b, ICPB-c, and ICPB-d ( Figure 5 ) was used for homogeneity determination. The results showed that the molecular weight distribution of the six components was not uniform and none of them was a uniform polysaccharide component.

[0071] 3. Summary.

[0072] Polysaccharides are usually composed of more than 10 monosaccharides through linear or branched glycosidic bonds, with a molecular weight of tens of thousands or even millions. They are a natural macromolecular polymer. Bioactive polysaccharides have always been a hot topic in various scientific fields at home and abroad. In recent years, the separation and analysis of polysaccharides have made great progress. With the in-depth study of polysaccharide structure, the structural characterization, physicochemical properties and potential mechanism of polysaccharides will be further clarified.

[67] Since polysaccharides from natural sources are effective substances for treating various diseases, the separation, purification and structural identification of polysaccharides are the prerequisites for studying the biological activity of polysaccharides and further developing and applying them.

[0073] The present invention firstly adopts the most conventional extraction method, i.e., water extraction and alcohol precipitation, to extract total polysaccharides from Imperata cylindrica roots. In the polysaccharide precipitation step, the volume fraction of ethanol in the system is set to 80%. Under this condition, most water-soluble polysaccharides can be precipitated and the components are relatively uniform. This method is not only simple to operate and highly repeatable, and can be applied in industrial production, but also better retains the activity of polysaccharides. DEAE cellulose is an anion exchanger. Its separation principle is to covalently connect positively charged groups to an inert carrier to adsorb and exchange negatively charged substances. The acidic components of polysaccharides release H +Negatively charged, it can be separated from neutral components through the ion adsorption and exchange of DEAE cellulose. During the experiment, it was found that the color of Imperata root polysaccharide was still dark after dialysis to remove impurities and pigments, and DEAE cellulose can also play a partial decolorization effect while separating polysaccharide components. In order to obtain a uniform polysaccharide fraction, ICPB was further purified using the molecular exclusion effect of agarose gel CL-4B to obtain four components: ICPB-a, ICPB-b, ICPB-c, and ICPB-d. Among them, the content of ICPB-a is too small, and the molecular weight of the remaining six groups of components was determined, and none of them were single polysaccharides. The next step will be to compare their activities through in vitro antioxidant experiments in order to carry out subsequent research.

[0074] 2. Study on the uric acid-lowering effect and mechanism of Imperata cylindrica root polysaccharide.

[0075] 1. Experimental animals.

[0076] The experimental animals and their conditions required for this experiment are shown in Table 3.

[0077] Table 3 Experimental animals and their conditions

[0078]

[0079] 2. Comparison of antioxidant activity of Imperata cylindrica root polysaccharide components.

[0080] 2.1 Comparison of DPPH scavenging effects.

[0081] ICP, ICPA, ICPB, ICPC, ICPB-d polysaccharide samples and Vc were fully dissolved in distilled water to prepare sample aqueous solutions with concentrations of 1000, 500, 250, 125, 62.5, 31.3, and 15.6 μg / mL. 100 μL of each solution was taken into a 96-well plate, and 100 μL of 10 mmol / mL DPPH solution was added. The samples were incubated in a 25°C incubator for 30 min, and the absorbance was measured at 517 nm. Vc aqueous solution was used as a standard antioxidant control. Each group of experiments was repeated 3 times.

[0082] The clearance rate is calculated as follows:

[0083] DPPH clearance rate (%) = [1-(A1-A2) / A0]*100%

[0084] In the formula, A1 is the absorbance value of 100 μL polysaccharide samples of different concentrations + 100 μL DPPH; A2 is the absorbance value of 100 μL polysaccharide samples of different concentrations + 100 μL H2O; A0 is the absorbance value of 100 μL H2O + 100 μL DPPH.

[0085] 2.2 Comparison of hydroxyl radical scavenging effects.

[0086] ICP, ICPA, ICPB, ICPC, ICPB-d polysaccharide samples and Vc were fully dissolved in distilled water to prepare sample aqueous solutions with concentrations of 1000, 500, 250, 125, 62.5, 31.3, and 15.6 μg / mL. 50 μL of each solution was taken into a 96-well plate, and 50 μL of 6 mmol / L FeSO4 solution and 6 mmol / L H2O2 solution were added respectively. After fully mixing, the samples were incubated in a 37°C incubator for 10 min. 50 μL of 6 mmol / L salicylic acid solution was added, the samples were fully mixed, and the samples were incubated again in a 37°C incubator for 30 min. The absorbance was measured at 520 nm, and Vc aqueous solution was used as a standard antioxidant control. Each group of experiments was repeated 3 times.

[0087] Hydroxyl radical scavenging rate (%) = [1-(A1-A2) / A0] × 100%

[0088] In the formula, A1 is 50 μL polysaccharide samples of different concentrations + 50 μL FeSO4 + 50 μL H2O2 + 50 μL salicylic acid; A2 is 50 μL samples of different concentrations + 50 μL FeSO4 + 50 μL distilled water + 50 μL salicylic acid; A0 is 50 μL distilled water + 50 μL FeSO4 + 50 μL H2O2 + 50 μL salicylic acid.

[0089] 3. Study on the uric acid-lowering effect and mechanism of ICPB-d.

[0090] 3.1 Animal grouping and model establishment.

[0091] Sixty healthy male mice weighing 18-22g were selected and fed with nutritious feed, with free access to food and water. After 3 days, they were randomly divided into 6 groups, with 10 mice in each group: blank group (CON), hyperuricemia model group (Mod), febuxostat group (Feb, 8mg / kg / d), colchicine group (Col, 1.35mg / kg / d), ICPB-d high-dose group (ICPB-dH, 87mg / kg / d); ICPB-d low-dose group (ICPB-dL, 40mg / kg / d). The mice were continuously gavaged according to the corresponding dose of body weight for 15 days, and the CON group and Mod group were gavaged with normal saline every morning. After 5 hours, except for the CON group, the other five groups of mice were gavaged with hypoxanthine (HX, 0.3g / kg / d) combined with oxonic acid potassium salt (OAPS, 0.3g / kg / d) solution, and the CON group was gavaged with normal saline. On the 16th day, except CON, the other five groups of mice were intraperitoneally injected with HX and OAPS solutions. 2 hours after modeling, blood was collected from the mouse eyeballs to prepare serum. The mice were killed, and the liver and kidney were quickly and completely removed. The residual blood stains around them were washed with normal saline, the water was absorbed by filter paper, weighed and marked, and frozen in an ultra-low temperature refrigerator. In addition, 2 mice were randomly selected from each group and anesthetized by intraperitoneal injection of 10% chloral hydrate (300 mg / kg). After anesthesia, the hearts of the mice were first quickly perfused with normal saline, and then slowly perfused with 4% paraformaldehyde for 30 minutes. When their whiskers moved, their front and back legs twitched, and their bodies were stiff, the kidney tissue was completely removed. Fix in 4% paraformaldehyde for 6 hours, soak in formalin, store at room temperature, prepare for embedding and staining, and perform renal tissue pathology observation.

[0092] 3.2 ICPB-d detected the levels of UA, CAT, IL-1β and TNF-a in mouse serum.

[0093] Two hours after intraperitoneal modeling and administration, blood was collected from the eyeball of each mouse, and the serum was allowed to stand for 1 hour and then centrifuged (4°C, 3500 r / min, 20 min). The upper serum was aspirated and used for detection of UA, CAT, IL-1β, and TNF-a levels using kits.

[0094] 3.3 ICPB-d detected the content of MDA and T-SOD in mouse kidney tissue.

[0095] Weigh 50 mg of mouse kidney tissue, add 9 times the mass fraction of normal saline, homogenize in ice water to prepare a 10% homogenate and centrifuge (4°C, 3500r / min, 10min), take the supernatant, and detect the MDA and T-SOD activities in the mouse liver according to the instructions of the kit.

[0096] 3.4ICPB-d detection of XOD content in mouse liver tissue.

[0097] Take 50 mg of mouse liver tissue, add 9 times the mass fraction of normal saline, homogenize in ice water to make 10% kidney tissue homogenate and centrifuge (4°C, 3500r / min, 10min), take the supernatant, and detect the XOD activity in mouse liver according to the kit instructions.

[0098] 3.5 Renal pathology examination.

[0099] Two mice were randomly selected from each group. After perfusion, the renal tissues were completely removed and then dehydrated with 75%, 85%, 90%, 95%, and 100% alcohol in a gradient manner and routinely paraffin-embedded. Specimen sections were made and HE staining was performed. The microscope was adjusted to 200 times to observe the pathological changes in the mouse kidneys.

[0100] 3.6 Effect of ICPB-d on the expression level of related proteins in mouse renal tissue.

[0101] Weigh about 100 mg of mouse kidney tissue and immediately place it in an ep tube. Add protein lysis solution containing 1% PMSF at a volume ratio of 1:10, lyse for 30 minutes, and place in a low temperature environment. Centrifuge for 10 minutes at a speed of 12000r / min and a temperature of 4°C to precipitate the kidney tissue, which is convenient for separating the supernatant. The protein concentration in the kidney tissue is determined by the BCA method. Add an appropriate amount of loading buffer to dilute the sample to 40μg protein per 20μL sample, heat and boil in a water bath for 5min, and the protein sample is ready. Add the configured 10% separation gel (configuration see Table 4) stably to the glass plate interlayer. Before adding, check whether there is a dirty plate surface or leakage in the glass plate interlayer. Use a 1mL pipette to add the separation gel to about two-thirds of the height of the glass plate. During this process, avoid bubbles, and finally press the water level to seal the liquid surface. Place it in a 37℃ incubator, prepare the concentrated gel (see Table 5), and after the separation gel is formed, use a filter paper strip to absorb the water layer, continue to add concentrated gel, insert the comb vertically and quickly into the concentrated gel to form a loading site, and place it in a constant temperature box again. When the concentrated gel is formed, pull out the comb vertically and load the sample. Electrophoresis, observe the marker band, and the separation effect is better in 1.5h. Take out the gel that has been electrophoresed, cut off the excess gel around, set the current to 300mA, and the transfer time is 1h. During this period, a PVDF membrane of appropriate size treated with methanol for 20s and water for 2min is used as a new protein carrier. After the transfer is completed, use TBS-T to block the blank position on the PVDF membrane. The blocking time is 1h, but the time can be adjusted appropriately according to the band situation. Add the primary antibody working solution NF-kB (1:1000), OAT1 (1:1000), OAT3 (1:1000), and soak overnight in a 4℃ environment. After the primary antibody incubation was completed, the membrane was washed with TBS-T, and the secondary antibody working solution (1:5000) was added each time and incubated at room temperature for 1 h. The membrane was washed with TBS-T, and the ECL chemiluminescent reagent was added and exposed using a gel imaging system.

[0102] Table 4 Separation gel configuration composition

[0103]

[0104] Table 5 Concentrated gel configuration composition

[0105]

[0106]

[0107] 3.7 Data processing.

[0108] The experimental data were statistically analyzed using SPSS16.0 software, and the charts were analyzed using GraphPad Prism5 software. One-way analysis of variance was used for comparison between samples, and t-test was used for comparison between groups. The data were expressed as mean ± standard deviation. When p < 0.05, it was considered to be significantly different; when p < 0.01, it was considered to be extremely significantly different.

[0109] 4. Experimental results.

[0110] 4.1DPPH removal effect.

[0111] DPPH clearance results are as follows Figure 6 As shown. ICP, ICPA, ICPB, ICPC, and ICPB-d all have scavenging effects on DPPH, and the concentration range is 15.6-1000μg / mL with a positive dose-effect correlation. When the concentration is 1mg / mL, the ICP clearance rate can reach up to 72.05%, the ICPA clearance rate can reach up to 62.83%, the ICPB clearance rate can reach up to 77.33%, and the ICPC clearance rate can reach up to 66.43%, among which the ICPB-d clearance rate can reach up to 83.01%. At the same concentration, the clearance rate of Vc is 96.83%. The specific values ​​are shown in Table 6.

[0112] Table 6 Removal data of DPPH by ICP, ICPA, ICPB, ICPC and ICPC-d

[0113]

[0114] 4.2 Comparative effects of hydroxyl radical scavenging.

[0115] Hydroxyl radical scavenging Figure 7 As shown in the results, ICP, ICPA, ICPB, ICPC and ICPC-d all have the function of scavenging hydroxyl free radicals, and the scavenging ability is positively correlated with the dose in the concentration range of 15.6-1000 μg / mL. When the concentration is 1 mg / mL, the scavenging rate of ICP can reach up to 5.22%, the scavenging rate of ICPA can reach up to 19.8%, the scavenging rate of ICPB can reach up to 51.01%, the scavenging rate of ICPC can reach up to 50.59%, and the scavenging rate of ICPB-d can reach up to 52.05%. The specific values ​​are shown in Table 7.

[0116] Table 7 Scavenging data of ICP, ICPA, ICPB, ICPC and ICPB-d on hydroxyl radicals

[0117]

[0118] 4.3 Effect of ICPB-d on the levels of UA, CAT, IL-1β and TNF-a in mouse serum.

[0119] like Figure 8 As shown in the figure, the activities of UA, CAT, IL-1β, and TNF-a in the serum of mice in the Mod group were significantly higher than those in the Con group (p<0.05 or p<0.01), and the uric acid in the model group was significantly increased, that is, the model was successfully established; compared with the Mod group, the UA levels in the ICPB-dL group and the ICPB-dH group were significantly reduced (p<0.01) and the CAT levels were significantly increased (p<0.05 or p<0.01); among them, the ICPB-dH group did not significantly reduce the uric acid level. In addition, TNF-α and IL-1β are very important pro-inflammatory factors that can cause cell inflammation and death. The effect of ICPB on the levels of TNF-α and IL-1β in the serum of mice is shown in the figure. The levels of TNF-α and IL-1β in the serum of mice in the Mod group were significantly higher than those in the Con group (p<0.01), indicating that there was an inflammatory response in the body. Compared with the Mod group, the levels of TNF-α and IL-1β in the serum of mice in the ICPB-dL group and the ICPB-dH group were significantly reduced (p<0.05 or p<0.01). The results showed that ICPB-d could significantly reduce the levels of UA, TNF-a, and IL-1β in the serum of hyperuricemia mice, and significantly increase the level of CAT.

[0120] 4.4 Effect of ICPB-d on the contents of MDA and T-SOD in mouse kidney tissue.

[0121] like Fig. 9 As shown in the figure, the MDA content in the kidney tissue of the mice in the Mod group was significantly higher than that in the Con group (p<0.05), and the T-SOD content was significantly lower than that in the Con group (p<0.01). Compared with the Mod group, the MDA content in the kidney tissue of the mice in the ICPB-dL group and ICPB-dH group was significantly reduced (p<0.01), and the T-SOD content was significantly increased (p<0.05, p<0.01). The results showed that ICPB-d could significantly reduce the MDA content in the kidney tissue of mice with hyperuricemia and significantly increase the T-SOD content.

[0122] 4.5 Effect of ICPB-d on XOD content in mouse liver tissue.

[0123] like Fig.10 As shown in the figure, the XOD content in the liver tissue of the mice in the Mod group was significantly higher than that in the CON group (p<0.01). Compared with the CON group, the reduction effect of XOD content in the ICPB-dL group was not significant, and the XOD content level in the ICPB-dH group was significantly reduced (p<0.05). The results showed that ICPB-d could reduce the XOD content in the liver tissue of mice, which further demonstrated that ICPB-d could reduce uric acid synthesis and improve uric acid accumulation in hyperuricemic nephropathy mice.

[0124] 4.6 Pathological changes in mouse renal tissue.

[0125] like Fig.11 As shown in the figure, under a 200x light microscope, the intercellular space of mice in the CON group was normal, with a clear and complete cell structure, and no obvious pathological changes. When ICPB-d was given for drug intervention, tubular dilatation was reduced, glomerular morphology was close to normal, and inflammatory cell infiltration was reduced. The results showed that ICPB-d extract can improve the pathological changes in the kidneys of mice with hyperuricemia.

[0126] 4.7 Effect of ICPB-d on the expression levels of related proteins in mouse renal tissue.

[0127] like Fig.12 As shown in the figure, Western blot results showed that compared with the CON group, the expression level of NF-κB protein in the kidney tissue of the mice in the Mod group was significantly increased (p<0.01), and the expression level of NF-κB protein in the kidney tissue of the mice in the ICPB-dL group and ICPB-dH group was significantly decreased (p<0.01). In addition, compared with the CON group, the expression levels of OAT1 and OTA3 proteins in the kidney tissue of the mice in the Mod group were significantly decreased (p<0.01), and compared with the Mod group, the expression levels of OAT1 and OTA3 proteins in the kidney tissue of the mice in the ICPB-dL group and ICPB-dH group were significantly increased (p<0.05 or p<0.01). The results showed that the regulatory effect of ICPB-d on the reduction of uric acid levels may be related to the reduction of NF-κB protein in the kidney tissue of mice and the upregulation of the expression of OAT1 and OTA3 proteins in the kidney tissue, and the effect of the low-dose group was more obvious than that of the high-dose group.

[0128] 5. Summary.

[0129] Under normal dietary conditions, the increase in UA levels in the body is caused by excessive uric acid production or low excretion, which leads to hyperuricemia. Therefore, reducing UA levels to normal values ​​is the main goal of lowering uric acid, which can be controlled by adjusting diet and taking drugs that lower serum uric acid. During the administration period, the mice in the CON group were in good spirits, with bright eyes, smooth and shiny hair, and agile and active behavior; after modeling, the uric acid level in the Mod group increased significantly, accompanied by irritability or depression, localized tingling, and systemic obesity, that is, the model was successfully established. XOD is mainly distributed in the liver of mice. When the content of XOD in the body increases, it will accelerate the rate of purine decomposition and lead to an increase in serum uric acid levels. Under normal conditions, a dynamic balance is maintained between oxidation and anti-oxidation. However, once stimulated, it will break the imbalance of the body, causing a large amount of reactive oxygen species in the body, activating downstream signaling pathways, and causing cell dysfunction, thereby leading to renal damage. The main function of SOD activity is to dismutate oxygen free radicals, and the level of activity can indirectly reflect the body's ability to scavenge oxygen free radicals. Free radicals attack unsaturated fatty acids in membrane lipids, causing them to oxidize. The content of lipid peroxidation product MDA will increase. By measuring the content of MDA in the body, the degree of damage to the body caused by free radicals in the body can be indirectly reflected. In addition, SOD can catalyze MDA to produce H2O2 and oxygen. H2O2 is a toxic byproduct of many normal metabolic activities. Most of the oxidative damage from oxidative stress is attributed to H2O2. In order to prevent it from causing damage to the body, it must be quickly converted into less active substances. One CAT molecule can catalyze the decomposition of millions of H2O2 molecules into molecular oxygen and water per second, keeping the H2O2 content in the cell at a safe level. TNF-α and IL-1β are important inflammatory mediators in the early stage of renal injury. The experimental results showed that the levels of TNF-α and IL-1β in the Mod group were significantly increased. The results showed that ICPB-d could significantly reduce the levels of UA, TNF-α, and IL-1β in mouse serum (p<0.05 and p<0.01), increase the level of CAT in serum (p<0.05 or p<0.01); significantly reduce the level of MDA in mouse kidney tissue (p<0.01), increase the level of T-SOD in mouse kidney tissue (p<0.05 or p<0.01); and significantly reduce the level of XOD in mouse liver tissue (p<0.05). This indicates that ICPB-d can reduce the generation of lipid oxidation metabolites and enhance the body's antioxidant capacity.

[0130] When defending against the invasion of foreign pathogens, inflammation is an important protective mechanism of the body in the long evolutionary process, and the persistence of inflammation or excessive response often induces disease. NF-κB is widely present in eukaryotic cells and is an important transcription factor with multidirectional transcriptional regulation. It is involved in a series of processes such as inflammatory response, oxidative stress, immune response, cell proliferation and apoptosis. It regulates the expression of inflammatory genes such as TNF-α and IL-6 promoter region. The results showed that ICPB-d can significantly inhibit the activation of NF-κB signaling pathway in mouse kidneys (p<0.01), inhibit inflammatory response, and improve kidney damage in hyperuricemia nephropathy mice, among which the effect of ICPB-dL group is more obvious than that of ICPB-dH.

[0131] Uric acid transporters can be divided into two categories: uric acid reabsorption transporters and uric acid secretion proteins. Uric acid secretion proteins include OAT1, OAT3, ABC transporter 2, urate transporter, phosphate transporter, and multidrug resistance protein 4. Among them, the expression levels of OAT1 and OAT3 distributed in proximal tubular epithelial cells are downregulated, resulting in increased renal uric acid reabsorption, decreased secretion, and obstructed uric acid excretion. The results showed that ICPB-d can significantly promote renal uric acid excretion by upregulating the expression levels of OAT1 and OAT3 proteins of uric acid-related transporters (p<0.05 or p<0.01), among which the effect of ICPB-dL group is more obvious than that of ICPB-dH.

[0132] In summary, ICPB-d has a good therapeutic effect on hyperuricemia mice. Its mechanism of action may be related to significantly reducing the uric acid level in mice, anti-inflammation, and promoting the secretion of uric acid, and it can effectively delay the progression of kidney disease in mice.

[0133] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An application of Imperata cylindrica polysaccharide for reducing uric acid in the preparation of a uric acid-reducing drug, the preparation method of the Imperata cylindrica polysaccharide comprising: The total polysaccharide of Imperata root is obtained by water extraction and alcohol precipitation, and the polysaccharide components of Imperata root are separated by an anion exchanger, and then purified to obtain Imperata root polysaccharide.

2. The use according to claim 1, characterized in that: The drug also includes pharmaceutically acceptable excipients.

3. The use according to claim 1, characterized in that: The drug reduces the activity of xanthine oxidase, increases the expression of OAT1 and OAT3 proteins in the kidney, regulates the activity of antioxidant enzymes in the body, inhibits the release of inflammatory factors, inhibits the production of uric acid, and reduces the serum uric acid level.

4. The use according to claim 1, characterized in that: The dosage form of the medicine is oral liquid, pill, granule, capsule, tablet, dripping pill, injection or powder.

5. The use according to any one of claims 1 to 4, characterized in that: The dosage of Imperata cylindrica polysaccharide is 35-90 mg / kg / d.

6. A method for preparing Imperata cylindrica polysaccharide for use in any one of claims 1 to 5, characterized in that: The following steps are involved: The Imperata root is subjected to water extraction and alcohol precipitation to obtain Imperata root total polysaccharide, and an anion exchanger is used to separate and obtain Imperata root polysaccharide components, and the Imperata root polysaccharide is purified to obtain Imperata root polysaccharide.

7. The preparation method according to claim 6, characterized in that: The water extraction and alcohol precipitation method comprises: adding ethanol to the Imperata root for reflux degreasing to obtain the residue, adding water for reflux extraction, combining the filtrate, suction filtering, filtering, taking the filtrate, concentrating, adding ethanol, standing for alcohol precipitation, removing the precipitate, washing, and drying to obtain the Imperata root total polysaccharide.

8. A uric acid-lowering drug, characterized in that: The invention comprises a pharmaceutically active ingredient and a pharmaceutically acceptable auxiliary material, wherein the pharmaceutically active ingredient comprises the Imperata cylindrica root polysaccharide used in any one of claims 1 to 5.

9. The drug according to claim 8, characterized in that The active pharmaceutical ingredients also include ingredients compatible with Imperata cylindrica polysaccharide.

10. Imperata cylindrica root polysaccharide obtained by the preparation method according to any one of claims 6 to 7.

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