Method for extracting polysaccharide from tripterygium wilfordii roots and application of polysaccharide

Abstract

The invention relates to a method for extracting polysaccharide from tripterygium wilfordii roots and application of the polysaccharide, and belongs to the field of biochemistry and molecular biology. The method comprises the following steps: soaking tripterygium wilfordii roots in ethanol, drying to constant weight, crushing, sieving, extracting in a water bath, deproteinizing, decoloring, precipitating in alcohol, dialyzing, freeze-drying and the like to obtain the water-soluble polysaccharide TWP. The polysaccharide is composed of rhamnose, arabinose, galactose, glucose, xylose, mannose and glucuronic acid, the weight-average molecular weight of the polysaccharide is 6713.235 kDa, the number-average molecular weight of the polysaccharide is 3188.859 kDa, and the polydispersity index of the polysaccharide is 2.105. The polysaccharide TWP has the effects of removing hydroxyl, superoxide anions, DPPH and ABTS free radicals, can remarkably reduce the expression level of inflammation-related factors and genes in LPS-induced macrophages, can improve the activity of SOD, CAT and GSH-Px and reduce the content of MDA, and can be used as a potential medicine component for relieving rheumatoid arthritis.

Description

Technical Field

[0001] The invention relates to a method for extracting polysaccharide from tripterygium wilfordii root and application thereof, and belongs to the field of biochemistry and molecular biology. Background Art

[0002] Tripterygium wilfordii is a deciduous, creeping shrub whose rhizomes are used as medicine, exhibiting potent anti-inflammatory, immunomodulatory, and anti-tumor effects. It is clinically used to treat rheumatoid arthritis by inhibiting T cell activation and the release of pro-inflammatory cytokines. Its bioactive extracts are now routinely used in the treatment of rheumatoid arthritis.

[0003] The anti-inflammatory activity of Tripterygium wilfordii extract has been widely studied by scholars, confirming that dihydro-β-agarwood furan sesquiterpenoid compounds in Tripterygium wilfordii roots have anti-neuroinflammatory activity, and its mechanism may be related to the inhibition of IκBα and p65 phosphorylation in the tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6) and nuclear factor-κB (NF-κB) signaling pathways.

[0004] Polysaccharides are high-molecular-weight polymers linked by glycosidic bonds. They possess not only excellent physical and chemical properties but also excellent biological activity. In addition to their antimicrobial activity, polysaccharides also exhibit anti-inflammatory, antioxidant, anti-tumor, hypoglycemic, hypolipidemic, anti-radiation, and immunomodulatory effects. Anti-inflammatory activity is a hallmark of polysaccharide bioactivity, particularly for low- or non-toxic, highly effective polysaccharides derived from plants.

[0005] Currently, there are few studies on the composition, anti-inflammatory activity and application of Tripterygium wilfordii polysaccharide. Therefore, research on the application of Tripterygium wilfordii polysaccharide is of great significance. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a method for extracting polysaccharides from the root of Tripterygium wilfordii and its application.

[0007] The technical solution adopted in the present invention is:

[0008] A method for extracting polysaccharides from the root of Tripterygium wilfordii comprises the following steps:

[0009] (1) Pretreatment of Tripterygium wilfordii root: soak the dried Tripterygium wilfordii root in 95% (v / v) ethanol for 6 hours; dry the soaked Tripterygium wilfordii root naturally, and then dry it to a constant weight; grind and sieve to obtain granules;

[0010] (2) Preparation of concentrated solution: add 15 times (w / v) deionized water to the granular material, heat to 80°C, stir for 1 hour to extract, filter and collect the filtrate; repeat the extraction once, combine the two filtrates, and concentrate the filtrate at 60°C and 0.1 MPa to obtain a concentrated solution;

[0011] (3) Decolorization: The concentrate was centrifuged at 10,000 × g for 10 minutes to obtain a supernatant; activated carbon was added to the supernatant for decolorization, and the mixture was stirred at 150 rpm at room temperature overnight to obtain a decolorized concentrate;

[0012] (4) Deproteinization: Add three volumes of Sevag reagent to the decolorized concentrate, shake vigorously, and centrifuge at 10,000 × g for 10 minutes to collect the supernatant; repeat the deproteinization process four times until no protein layer is precipitated in the centrifuge tube; add four volumes of ethanol to the supernatant, let it stand at 4°C overnight, and collect the precipitate;

[0013] (5) Dialysis: The precipitate was dissolved in deionized water and dialyzed for 48 hours using a dialysis bag with a molecular weight of 10.0 kDa; the dialysate was collected and freeze-dried to obtain the water-soluble polysaccharide TWP of Tripterygium wilfordii.

[0014] Furthermore, the volume of the concentrate is 1 / 10 of the volume of the two filtrates. The ratio of activated carbon added in step (3) is 2 g / 100 mL of supernatant. The composition of the Sevag reagent in step (4) is chloroform: n-butanol = 3:1 (v / v). The composition of the water-soluble polysaccharide of Tripterygium wilfordii described in step (5) is rhamnose, arabinose, galactose, glucose, xylose, mannose and glucuronic acid. The weight average molecular weight and number average molecular weight of the water-soluble polysaccharide of Tripterygium wilfordii described in step (5) are 6713.235 kDa and 3188.859 kDa, respectively, and the polydispersity index is 2.105.

[0015] The composition of Tripterygium wilfordii polysaccharide is rhamnose, arabinose, galactose, glucose, xylose, mannose, and glucuronic acid, with a molar ratio of 16.0967:8.3376:27.925:16.378:0.5017:0.4017:6.4507. The weight-average molecular weight and number-average molecular weight of Tripterygium wilfordii polysaccharide are 6713.235 kDa and 3188.859 kDa, respectively, with a polydispersity index of 2.105.

[0016] Application of water-soluble polysaccharide of Tripterygium wilfordii in the preparation of medicine for treating rheumatoid arthritis.

[0017] Beneficial effects of the present invention

[0018] (1) The present invention provides a method for extracting Tripterygium wilfordii polysaccharide, wherein the root of Tripterygium wilfordii is treated with ethanol soaking, drying, crushing and screening, water bath extraction, deproteinization, decolorization, alcohol precipitation, dialysis and freeze drying to obtain a water-soluble polysaccharide TWP (Tripterygium wilfordii polysaccharide). The method adopts low-temperature extraction, refines the process flow and parameters, obtains the water-soluble polysaccharide, and determines the specific components of the polysaccharide, which is of great significance for studying the performance and function of the polysaccharide TWP.

[0019] (2) The polysaccharide TWP extracted by the present invention has the function of scavenging free radicals such as hydroxyl, superoxide anion, DPPH and ABTS, and can significantly reduce the expression levels of inflammation-related factors and genes in LPS-induced RAW 264.7 macrophages, increase the activities of SOD, CAT and GSH-Px, and reduce the content of MDA. It can be used as a potential drug component for rheumatoid arthritis.

[0020] (3) The extracted polysaccharide TWP was analyzed for its composition. The polysaccharide was composed of rhamnose, arabinose, galactose, glucose, xylose, mannose, and glucuronic acid in a molar ratio of 16.0967:8.3376:27.925:16.378:0.5017:0.4017:6.4507. The weight-average molecular weight and number-average molecular weight of the polysaccharide were 6713.235 kDa and 3188.859 kDa, respectively, and the polydispersity index was 2.105. The polysaccharide had a moderate composition and molecular weight and exhibited excellent antioxidant and anti-inflammatory activities.

[0021] (4) The polysaccharide TWP extracted by the present invention can be used as a potential pharmaceutical ingredient for alleviating rheumatoid arthritis, which is of great significance for further developing drugs for rheumatoid arthritis using the extract. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FT-IR spectrum of the polysaccharide TWP of the present invention;

[0023] Figure 2 The nuclear magnetic resonance spectrum of the polysaccharide TWP of the present invention;

[0024] Figure 3 The scavenging rate of the polysaccharide TWP of the present invention on hydroxyl radicals (A), superoxide radicals (B), ABTS (C) and DPPH (D);

[0025] Figure 4 The cell viability of the polysaccharide TWP of the present invention varies with concentration;

[0026] Figure 5Effects of the polysaccharide TWP of the present invention on the activities of TNF-α (A), IL-1β (B), IL-6 (C) and NO (D) in LPS-induced RAW 264.7 macrophages;

[0027] Figure 6 Effects of the polysaccharide TWP of the present invention on LPS-induced inflammation-related genes iNOS (A), TNF-α (B), IL-1β (C) and IL-6 (D) in RAW 264.7 macrophages;

[0028] Figure 7 Effects of the polysaccharide TWP of the present invention on the activities of SOD (A), CAT (B), GSH-Px (C) and MDA (D) in RAW 264.7 macrophages induced by LPS. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below with reference to specific embodiments.

[0030] Unless otherwise specified, the instruments and equipment involved in the examples are all conventional instruments and equipment; the raw materials involved are all commercially available conventional raw materials; and the experimental methods involved are all conventional methods.

[0031] The reagents involved in the examples: CCK-8 kit, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), enzyme-linked immunosorbent assay (ELISA) kit, were all purchased from Shanghai Beyotime Biotechnology Co., Ltd.

[0032] Example 1: A method for extracting polysaccharides from the root of Tripterygium wilfordii, comprising the following steps:

[0033] (1) Pretreatment of Tripterygium wilfordii root

[0034] The dried Tripterygium wilfordii root was soaked in 95% (v / v) ethanol for 6 hours with intermittent stirring to remove fat-soluble components and pigments; the soaked Tripterygium wilfordii root was collected, naturally dried to remove residual ethanol, and then dried in a 60°C oven to constant weight; the dried Tripterygium wilfordii root was crushed and sieved to collect 20-40 mesh granules;

[0035] (2) Preparation of concentrated solution: add 15 times (w / v) deionized water to the pellets, heat to 80°C, stir for 1 hour, filter, and collect the filtrate; repeat the extraction once, combine the two filtrates; concentrate the filtrate at 60°C and 0.1 MPa to 1 / 10 of the volume of the two filtrates to obtain a concentrated solution;

[0036] (3) Decolorization: The concentrate was centrifuged at 10,000 × g for 10 minutes to remove insoluble matter and obtain a supernatant; activated carbon was added to the supernatant at a rate of 2 g / 100 mL of supernatant, and the mixture was decolorized overnight at room temperature with magnetic stirring at a speed of 150 r / min, followed by centrifugation at 5,000 × g for 10 minutes, and the supernatant was collected to obtain a decolorized concentrate;

[0037] (4) Deproteinization: Add three volumes of Sevag reagent (chloroform: n-butanol = 3:1, volume ratio) to the decolorized concentrate, shake vigorously, centrifuge at 10,000 × g for 10 minutes, and collect the supernatant; repeat the deproteinization process five times until no protein precipitates in the centrifuge tube; add four volumes of ethanol to the supernatant, let it stand at 4°C overnight, and collect the precipitate;

[0038] (5) Dialysis: The precipitate was redissolved in deionized water and dialyzed for 48 hours using a dialysis bag with a molecular weight of 10.0 kDa; the dialysate was collected and freeze-dried to obtain Tripterygium wilfordii water-soluble polysaccharide (TWP).

[0039] Example 2: Component Analysis of Tripterygium Wilfordii Polysaccharide TWP of Example 1

[0040] 2.1 Basic ingredients

[0041] The carbohydrate content in the polysaccharide TWP of Example 1 was determined by anthrone-sulfuric acid colorimetry using glucose as a standard; and the protein content was determined by Coomassie brilliant blue method using bovine serum albumin as a standard.

[0042] The results are shown in Table 1. The yield of polysaccharide TWP was 3.91%, and the carbohydrate and protein contents were 90.77% and 2.67%, respectively.

[0043] Table 1 Basic component analysis of polysaccharide TWP extracted from Tripterygium wilfordii stem

[0044]

[0045] 2.2 Composition and molecular weight determination of polysaccharide TWP

[0046] The composition and molecular weight of polysaccharide TWP were determined by high performance anion exchange chromatography (HPAEC) and high performance gel filtration chromatography (HPGFC).

[0047] Composition detection: 12 mg of polysaccharide TWP was dissolved in 18 mL of 2 mol / L trifluoroacetic acid, stoppered, and placed in a metal bath for hydrolysis at 110°C for 3 h. After hydrolysis, it was transferred to a wedge-shaped flask and rinsed with pure water three times. The rinse water was also transferred to the wedge-shaped flask and evaporated to dryness under reduced pressure at 40°C on a rotary evaporator. Then, 3 mL of methanol was added and evaporated to dryness. This was repeated five times to remove residual trifluoroacetic acid. After evaporation, 1 mL of pure water was used to dissolve the solid at the bottom of the flask and rinse the wedge-shaped flask. The solution was collected in a 2 mL centrifuge tube, fixed to volume, and detected by high-performance anion exchange chromatography.

[0048] Molecular weight detection: 0.1g polysaccharide TWP was dissolved in 10mL of 0.1mol / L NaNO3 solution, filtered with a 0.22μm microporous membrane, and injected with an injection volume of 20μL. Then, high performance gel filtration chromatography was used for detection. W Molecular weight calibration curves were drawn for 270,000, 975,000, 3,680,000, and 13,535,000 Da dextran standards, and the molecular weight of the polysaccharide was calculated based on the sample retention time and the calibration curve.

[0049] The test results are shown in Table 2. It can be seen that the polysaccharide TWP is composed of rhamnose, arabinose, galactose, glucose, xylose, mannose and glucuronic acid with a molar ratio of 16.0967:8.3376:27.925:16.378:0.5017:0.4017:6.4507.

[0050] Table 2 Composition of Tripterygium wilfordii polysaccharide TWP

[0051]

[0052] Further analysis showed that the weight average molecular weight (Mw) and number average molecular weight (Mn) of polysaccharide TWP were 6713.235 kDa and 3188.859 kDa, respectively, and the polydispersity index was 2.105.

[0053] 2.3 Fourier transform infrared spectroscopy analysis of polysaccharide TWP

[0054] The possible functional groups in polysaccharide TWP were analyzed by FT-IR. Figure 1 shown.

[0055] 3400cm -1 ~3200cm -1 The peak at 3000 cm may be related to the intermolecular hydrogen bond and OH stretching vibration of hydroxyl groups; -1 to 2900cm -1 The peak at 1600 cm may correspond to the CH2 asymmetric stretching vibration, which is the characteristic absorption peak of polysaccharides; -1 ~1400cm -1The peak at 1400 cm may be derived from CH2 symmetric ring stretching vibration or CH2 shear vibration; -1 ~1100cm -1 The peaks between 900 cm and 900 cm may be related to the OH in-plane deformation, COC antisymmetric stretching and CO stretching. -1 ~500cm -1 The peaks in between may be related to the stretching of the C-terminal group and the stretching of the pyran ring.

[0056] 2.4 Nuclear magnetic resonance spectroscopy (NMR) analysis of polysaccharide TWP

[0057] The chemical bonds of polysaccharide TWP were further studied by nuclear magnetic resonance spectroscopy (NMR). Figure 2 shown.

[0058] Figure 2 A is polysaccharide 1 In the H NMR spectrum, the peak between 4.62 ppm and 4.63 ppm may be attributed to the ectopic atoms of β-1,3-D-glucose, the peak around 4.5 ppm may be induced by the β-isomer proton, the peak between 3.7 ppm and 3.8 ppm may be related to the H in -OH, and the peak between 3.4 ppm and 3.6 ppm may be related to the CC signal.

[0059] Figure 2 B is polysaccharide 13 In the C NMR spectrum, the signals between 96 ppm and 100 ppm are C=C bonds; the signals between 65 ppm and 75 ppm are related to HC≡CH; the signals between 60 ppm and 65 ppm correspond to CH, CH2, and CH3; and the signals between 10 ppm and 35 ppm are derived from the methyl groups of rhamnose and galactose.

[0060] The above results show that the polysaccharide TWP of the present invention has a typical polysaccharide characteristic spectrum.

[0061] Example 3: In vitro antioxidant activity of polysaccharide TWP

[0062] The polysaccharide TWP of Example 1 was dissolved in deionized water and diluted to 0.5 mg / mL, 1.0 mg / mL, 1.5 mg / mL, 2.0 mg / mL and 2.5 mg / mL, respectively. The dilutions of Vc at the same multiples were used as controls. The mixture was filtered through a 0.22 μm aqueous filter membrane to determine the scavenging ability of the polysaccharide TWP for DPPH (1,1-diphenyl-2-picrylhydrazyl free radical), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt), hydroxyl and superoxide anion free radicals.

[0063] The results are as follows Figure 3 shown. Figure 3A and 3B showed that as the polysaccharide concentration increased from 0.5 mg / mL to 2.5 mg / mL, the scavenging rates of TWP for hydroxyl and superoxide anion radicals increased slightly, from 35.39% ± 3.18% to 53.72% ± 5.47% and from 61.89% ± 6.29% to 70.23% ± 2.41%, respectively.

[0064] Figure 3 C and 3D show that the scavenging rate of TWP for ABTS and DPPH free radicals is close to 100% in the concentration range of 0.5 mg / mL to 2.5 mg / mL.

[0065] In the figure, * indicates p < 0.05, ** indicates p < 0.01, indicating significant differences compared with Vc.

[0066] Example 4. Safety Analysis of Polysaccharide TWP

[0067] RAW 264.7 macrophages were cultured in DMEM supplemented with 10% (v / v) fetal bovine serum, 100 U / mL penicillin, and 100 μg / mL streptomycin in a 37°C, 5% CO2 incubator. Meanwhile, the polysaccharide TWP from Example 1 was dissolved in DMEM to prepare DMEM solutions with different TWP concentrations (0.3125, 0.625, 1.25, 2.5, and 5.0 mg / mL), which were then filtered through a 0.22 μm aqueous filter.

[0068] RAW 264.7 macrophages were cultured at a volume of 2 × 10 4 Cells were seeded into 96-well plates at a density of 10 cells / mL and incubated at 37°C, 5% CO₂ for 24 hours. Subsequently, 100 μL of DMEM solution with varying TWP concentrations was added to each well and incubated for another 24 hours. Cell viability was assessed using a CCK-8 kit according to the manufacturer's instructions.

[0069] The results are as follows Figure 4 As shown in the figure, within the concentration range of 0.3125 mg / mL to 5.0 mg / mL, the cell viability was higher than 100%, indicating that TWP has good safety. When the TWP concentration reached 5.0 mg / mL, the cell viability decreased to a certain extent.

[0070] Example 5. Analysis of anti-inflammatory activity of polysaccharide TWP

[0071] RAW 264.7 macrophages (4×10 4The inflammatory model was established by treating RAW 264.7 cells with 1 μg / mL LPS for 24 hours. Subsequently, LPS-treated RAW 264.7 cells were co-cultured with different concentrations of the polysaccharide TWP (0.3125, 0.625, 1.25, and 2.5 mg / mL) for 24 hours. An equal amount of DMEM without polysaccharide was used as a control group. Finally, a portion of the RAW 264.7 cells was used to measure the levels of NO, TNF-α, IL-6, IL-1β, SOD, GSH-Px, MDA, and CAT using ELISA kits. Another portion of the cells was treated with cell lysate, and the expression of inflammation-related genes was studied using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR).

[0072] The primers used in the experiment are shown in Table 3. β-actin gene was used as the internal reference. All samples were tested in triplicate. The gene expression levels were measured by 2 -ΔΔCT The result is as follows: Figures 5-7 shown.

[0073] Table 3 Genes and primers used in RT-qPCR reactions

[0074]

[0075] from Figure 5 It can be seen that polysaccharide TWP effectively reduced the levels of inflammatory-related factors in LPS-induced RAW 264.7 macrophages in a significant concentration-dependent manner.

[0076] Figure 5 A, B, C, and D are the expression levels of inflammatory factors TNF-α, IL-1β, IL-6, and NO, respectively. The expression levels of TNF-α, IL-1β, IL-6, and NO in LPS-induced macrophages RAW 264.7 reached 457.872±18.826 ng / L, 91.544±5.548 pg / mL, 85.125±1.549 pg / mL, and 255.154±10.643 μmol / L, respectively. After treatment with 2.5 mg / mL polysaccharide TWP for 24 hours, the expression levels of TNF-α, IL-1β, IL-6, and NO decreased to 312.708±13.765 ng / L, 52.634±3.764 pg / mL, 46.433±3.424 pg / mL, and 148.543±7.643 μmol / L, respectively.

[0077] Figure 6 It can be seen that polysaccharide TWP significantly inhibited the expression of inflammation-related genes in RAW 264.7 macrophages induced by LPS in the same manner.

[0078] Figure 6A, B, C, and D are the expression levels of inflammatory factor-related genes iNOS, TNF-α, IL-1β, and IL-6, respectively; the expression levels of iNOS, TNF-α, IL-1β, and IL-6 genes in LPS-induced macrophages RAW 264.7 were 18.53, 24.55, 14.75, and 29.31 times of the original levels, respectively. After treatment with 2.5 mg / mL polysaccharide TWP for 24 hours, the expression levels of iNOS, TNF-α, IL-1β, and IL-6 genes in LPS-induced macrophages RAW 264.7 were reduced to 6.55, 9.29, 5.74, and 9.88 times of the original levels, respectively.

[0079] Figure 7 It can be seen that the polysaccharide TWP significantly increased the levels of SOD, CAT, and GSH-Px in LPS-induced RAW 264.7 macrophages in a concentration-dependent manner and reduced the content of MDA, indicating that polysaccharides can regulate the body's oxidative stress and alleviate inflammatory responses.

[0080] in, Figure 7 A, B, C, and D represent the activities of SOD, CAT, GSH-Px, and MDA in macrophages, respectively. The levels of SOD, CAT, and GSH-Px in LPS-induced RAW 264.7 macrophages were 0.547±0.167 units, 6.544±0.968 units / mL, and 4.866±1.215 mU / mL, respectively. After treatment with 2.5 mg / mL polysaccharide TWP for 24 hours, the levels of SOD, CAT, and GSH-Px increased to 2.495±0.196 units / mL, 17.651±1.138 units / mL, and 12.236±1.034 mU / mL, respectively. MDA decreased from 27.876±2.013 μmol / L to 11.651±1.862 μmol / L.

Claims

1. A method for extracting polysaccharides from the root of Tripterygium wilfordii, comprising the following steps: (1) Pretreatment of Tripterygium wilfordii root: soak the dried Tripterygium wilfordii root in 95% (v / v) ethanol for 6 hours; dry the soaked Tripterygium wilfordii root naturally, and then dry it to a constant weight; grind and sieve to obtain granules; (2) Preparation of concentrated solution: add 15 times (w / v) deionized water to the granular material, heat to 80°C, stir for 1 hour to extract, filter and collect the filtrate; repeat the extraction once, combine the two filtrates, and concentrate the filtrate at 60°C and 0.1 MPa to obtain a concentrated solution; (3) Decolorization: The concentrate was centrifuged at 10,000 × g for 10 minutes to obtain a supernatant; activated carbon was added to the supernatant for decolorization, and the mixture was stirred at 150 rpm at room temperature overnight to obtain a decolorized concentrate; (4) Deproteinization: Add three volumes of Sevag reagent to the decolorized concentrate, shake vigorously, and centrifuge at 10,000 × g for 10 minutes to collect the supernatant; repeat the deproteinization process four times until no protein layer is precipitated in the centrifuge tube; add four volumes of ethanol to the supernatant, let it stand at 4°C overnight, and collect the precipitate; (5) Dialysis: The precipitate was dissolved in deionized water and dialyzed for 48 hours using a dialysis bag with a molecular weight of 10.0 kDa; the dialysate was collected and freeze-dried to obtain the water-soluble polysaccharide TWP of Tripterygium wilfordii.

2. The method for extracting polysaccharides according to claim 1, wherein The volume of the concentrate is 1 / 10 of the volume of the two filtrates.

3. The method for extracting polysaccharides according to claim 1, wherein The ratio of activated carbon added in step (3) is 2 g / 100 mL supernatant.

4. The method for extracting polysaccharides according to claim 1, wherein Step (4) The composition of Sevag reagent is chloroform: n-butanol = 3:1 (v / v).

5. The method for extracting polysaccharides according to claim 1, wherein The composition of the water-soluble polysaccharide of Tripterygium wilfordii in step (5) is rhamnose, arabinose, galactose, glucose, xylose, mannose and glucuronic acid.

6. The method for extracting polysaccharides according to claim 1, wherein The weight average molecular weight and number average molecular weight of the water-soluble Tripterygium wilfordii polysaccharide described in step (5) are 6713.235 kDa and 3188.859 kDa, respectively, and the polydispersity index is 2.

105.

7. A water-soluble polysaccharide from Tripterygium wilfordii extracted by the method of claim 1, characterized in that: The water-soluble polysaccharide of Tripterygium wilfordii is composed of rhamnose, arabinose, galactose, glucose, xylose, mannose and glucuronic acid, and the molar ratio thereof is 16.0967:8.3376:27.925:16.378:0.5017:0.4017:6.4507.

8. The water-soluble Tripterygium wilfordii polysaccharide according to claim 7, wherein The weight average molecular weight and number average molecular weight of the water-soluble Tripterygium wilfordii polysaccharide are 6713.235 kDa and 3188.859 kDa respectively, and the polydispersity index is 2.

105.

9. Use of the water-soluble polysaccharide of Tripterygium wilfordii according to claim 7 in preparing a drug for treating rheumatoid arthritis.

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