Traditional Chinese medicinal material polysaccharide extraction method

Abstract

The invention provides a traditional Chinese medicinal material polysaccharide extraction method, which takes dendrobium officinale as a raw material, and comprises the following steps: S1, washing, airing, crushing and sieving dendrobium officinale to obtain 50-80-mesh dendrobium officinale coarse powder, S2, adding the dendrobium officinale coarse powder into a buffer solution, and stirring to prepare a dendrobium officinale suspension, S3, placing the dendrobium officinale suspension in a 40kHz ultrasonic environment for 20-40 minutes, and filtering to obtain the traditional Chinese medicinal material polysaccharide. The method comprises the following steps: S1, preparing a dendrobium nobile suspension, S2, preparing a dendrobium nobile suspension, S4, putting the dendrobium nobile suspension treated in the step S3 in a 300W microwave environment for 120-210 seconds, S5, adding an aqueous two-phase extracting agent into the dendrobium nobile suspension treated in the step S4, stirring, uniformly mixing, standing for 30 minutes, centrifuging for 5 minutes, and performing aqueous two-phase separation, and S6, collecting upper-layer liquid and lower-layer liquid, and dialyzing, concentrating and drying the upper-layer liquid to obtain the dendrobium nobile polysaccharide. Through combined application of ultrasonic-microwave-aqueous two-phase extraction, the extraction process is efficient and rapid.

Description

Technical Field

[0001] The invention relates to the field of Chinese medicinal material extraction, and in particular to a method for extracting polysaccharides from Chinese medicinal materials. Background Art

[0002] After thousands of years of inheritance and development, we have accumulated rich clinical experience and medicinal knowledge. A large number of studies have shown that Chinese herbal polysaccharides have multiple biological activities and pharmacological effects. With people's growing demand for health and the pursuit of natural and safe drugs, Chinese herbal polysaccharides have become a research hotspot in the medical field due to their natural sources, few side effects, and wide biological activities.

[0003] Dendrobium is a traditional Chinese medicinal material, and polysaccharides are one of its important active ingredients. The polysaccharide content in Dendrobium candidum is relatively high. The "Chinese Pharmacopoeia" stipulates that the polysaccharide content of Dendrobium candidum shall not be less than 25.0%. Polysaccharides have strong biological activities such as anti-tumor, antioxidant, immunity enhancement, lowering blood sugar and blood lipids, and relieving fatigue. In addition, the polysaccharide content is one of the standards for measuring the efficacy of Dendrobium candidum. Therefore, extracting polysaccharide components from Dendrobium candidum for development has become a research hotspot today.

[0004] The extraction methods of Dendrobium polysaccharides include hot water extraction, ultrasonic-assisted extraction, alkaline solution extraction, acid extraction, enzyme extraction, microwave-assisted extraction, etc. Among them, hot water extraction is the most widely used, but it has high temperature requirements, is time-consuming, and the extract contains more impurities, which affects the purity and quality of the polysaccharides and reduces their biological activity and application value. Therefore, a method for extracting polysaccharides from Chinese medicinal materials is proposed to solve this problem. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for extracting polysaccharides from Chinese medicinal materials. The specific technical scheme is as follows:

[0006] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0007] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0008] S2: adding the crude powder of dendrobium to the buffer solution, stirring, and obtaining a suspension of dendrobium;

[0009] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 20-40 minutes, with the temperature controlled at 20°C-40°C;

[0010] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 120-210 seconds;

[0011] S5: adding the aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0012] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0013] As an improvement of the above technical solution, the buffer solution in step S2 is a phosphate buffer solution with a pH of 7.0-7.4, and the solid-liquid ratio of the dendrobium crude powder to the phosphate buffer solution is 1:5-1:10;

[0014] As an improvement of the above technical solution, the phosphate buffer is made of sodium dihydrogen phosphate, disodium hydrogen phosphate and distilled water;

[0015] As an improvement of the above technical solution, in step 5, the two-phase aqueous extractant is composed of polyethylene glycol and sodium dihydrogen phosphate, and the liquid-to-solid ratio of the two-phase aqueous extractant to the coarse powder of Dendrobium officinale is 1:20-1:40;

[0016] As an improvement of the above technical solution, the ratio of polyethylene glycol to sodium dihydrogen phosphate in the double water extractant is 1:1-1:4;

[0017] As an improvement of the above technical solution, the polyethylene glycol is a medium molecular weight polyethylene glycol of polyethylene glycol 2000-polyethylene glycol 4000;

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] 1. The combined application of ultrasound-microwave-aqueous two-phase extraction makes the extraction process efficient and rapid. The cavitation effect, mechanical effect and thermal effect generated by ultrasound combined with the thermal effect of microwaves can accelerate cell breakage and promote the release of polysaccharides from Dendrobium cells. Then, aqueous two-phase extraction is carried out. The extraction process is rapid and efficient.

[0020] 2. The medium molecular weight polyethylene glycol is used to make the two-phase aqueous extractant, which has good fluidity at room temperature, is conducive to the rapid formation of the two-phase aqueous system, improves the convenience and efficiency of operation, reduces the extraction of impurities, improves the purity of polysaccharides, is reasonably priced, and is suitable for expansion in production.

[0021] 3. The extraction solvent has low toxicity. The polyethylene glycol and sodium dihydrogen phosphate used in the present invention are widely used in the food industry and have low toxicity. The raw materials are environmentally friendly and safe. In addition, both the buffer solution and the two-phase aqueous extractant contain sodium dihydrogen phosphate, which reduces the use of sodium dihydrogen phosphate.

[0022] 4. Simple collection. After separation of the two aqueous phases, the upper phase is polyethylene glycol solution and the lower phase is sodium dihydrogen phosphate solution. Polysaccharides are enriched in the upper phase, and impurities and residues enter the lower phase, which is conducive to the collection of polysaccharides. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The Dendrobium officinale of the present invention is produced in Lu'an, Anhui Province, and is a three-year-old Dendrobium officinale.

[0025] The polyethylene glycol, sodium dihydrogen phosphate and disodium hydrogen phosphate used in the present invention can all be purchased from commercial channels.

[0026] The polysaccharide content detection method of the present invention is the phenol-sulfuric acid method.

[0027] Material configuration:

[0028] Preparation of phosphate buffered saline

[0029] Weigh sodium dihydrogen phosphate and distilled water (15 g / L), add sodium dihydrogen phosphate into distilled water, stir, add disodium hydrogen phosphate to adjust the pH value to between 7.0 and 7.4, and make up to volume for later use.

[0030] Example 1

[0031] Preparation of aqueous two-phase extractant

[0032] Weigh polyethylene glycol 2000 (PEG2000), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 2000 to sodium dihydrogen phosphate is 1:1, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 2000 and sodium dihydrogen phosphate is 4:1. Divide the distilled water equally, dissolve polyethylene glycol 2000 and sodium dihydrogen phosphate in the distilled water respectively, mix the solutions and make up to volume.

[0033] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0034] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0035] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0036] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0037] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0038] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0039] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0040] Example 2

[0041] Preparation of aqueous two-phase extractant

[0042] Weigh polyethylene glycol 2000 (PEG2000), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 2000 to sodium dihydrogen phosphate is 1:4, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 2000 and sodium dihydrogen phosphate is 4:1. Divide the distilled water equally, dissolve polyethylene glycol 2000 and sodium dihydrogen phosphate in the distilled water respectively, mix the solutions and make up to volume.

[0043] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0044] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0045] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0046] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0047] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0048] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0049] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0050] Example 3

[0051] Preparation of aqueous two-phase extractant

[0052] Weigh polyethylene glycol 4000 (PEG4000), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 4000 to sodium dihydrogen phosphate is 1:1, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 2000 and sodium dihydrogen phosphate is 4:1. Distilled water is divided equally, polyethylene glycol 4000 and sodium dihydrogen phosphate are dissolved in distilled water respectively, and then the solutions are mixed and fixed to volume.

[0053] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0054] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0055] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0056] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0057] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0058] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0059] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0060] Example 4

[0061] Preparation of aqueous two-phase extractant

[0062] Weigh polyethylene glycol 4000 (PEG4000), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 4000 to sodium dihydrogen phosphate is 1:4, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 2000 and sodium dihydrogen phosphate is 4:1. Divide the distilled water equally, dissolve polyethylene glycol 4000 and sodium dihydrogen phosphate in the distilled water respectively, mix the solutions and make up to volume.

[0063] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0064] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0065] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0066] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0067] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0068] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0069] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0070] Example 5

[0071] Preparation of aqueous two-phase extractant

[0072] Weigh polyethylene glycol 3000 (PEG3000), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 3000 to sodium dihydrogen phosphate is 1:2.5, and the mass ratio of distilled water to the sum of the mass of polyethylene glycol 2000 and sodium dihydrogen phosphate is 4:1. Distilled water is divided equally, polyethylene glycol 3000 and sodium dihydrogen phosphate are dissolved in distilled water respectively, and then the solutions are mixed and fixed to volume.

[0073] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0074] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0075] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0076] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0077] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0078] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0079] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0080] Comparative Example 1

[0081] Preparation of aqueous two-phase extractant

[0082] Weigh polyethylene glycol 600 (PEG600), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 600 to sodium dihydrogen phosphate is 0.8:1, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 600 and sodium dihydrogen phosphate is 4:1. Divide the distilled water equally, dissolve polyethylene glycol 600 and sodium dihydrogen phosphate in the distilled water respectively, mix the solutions and make up to volume.

[0083] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0084] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0085] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0086] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0087] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0088] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0089] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0090] Comparative Example 2

[0091] Preparation of aqueous two-phase extractant

[0092] Weigh polyethylene glycol 6000 (PEG6000), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 6000 to sodium dihydrogen phosphate is 0.8:1, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 6000 and sodium dihydrogen phosphate is 4:1. Distilled water is divided equally, polyethylene glycol 6000 and sodium dihydrogen phosphate are dissolved in distilled water respectively, and then the solutions are mixed and fixed to volume.

[0093] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0094] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0095] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0096] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0097] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0098] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0099] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0100] Comparative Example 3

[0101] Preparation of aqueous two-phase extractant

[0102] Weigh polyethylene glycol 600 (PEG600), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 600 to sodium dihydrogen phosphate is 1:5, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 600 and sodium dihydrogen phosphate is 4:1. Divide the distilled water equally, dissolve polyethylene glycol 600 and sodium dihydrogen phosphate in the distilled water respectively, mix the solutions and make up to volume.

[0103] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0104] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0105] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0106] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0107] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0108] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0109] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0110] Comparative Example 4

[0111] Preparation of aqueous two-phase extractant

[0112] Weigh polyethylene glycol 6000 (PEG6000), sodium dihydrogen phosphate and distilled water. The mass ratio of polyethylene glycol 6000 to sodium dihydrogen phosphate is 1:5, and the mass ratio of distilled water to the sum of the masses of polyethylene glycol 6000 and sodium dihydrogen phosphate is 4:1. Divide the distilled water equally, dissolve polyethylene glycol 6000 and sodium dihydrogen phosphate in the distilled water respectively, mix the solutions and make up to volume.

[0113] A method for extracting polysaccharides from traditional Chinese medicine, using Dendrobium officinale as raw material, comprises the following steps:

[0114] S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium coarse powder;

[0115] S2: Add 100 g of dendrobium crude powder into 800 mL of phosphate buffer solution and stir to obtain a dendrobium suspension;

[0116] S3: placing the Dendrobium suspension in a 40kHz ultrasonic environment for 30 minutes, with the temperature controlled at 25°C;

[0117] S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 150 seconds;

[0118] S5: adding 2 L of aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase;

[0119] S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

[0120] The weight of the Dendrobium polysaccharide obtained by each extraction was weighed, and its polysaccharide content was measured, see Table 1.

[0121]

[0122]

[0123] Table 1

[0124] As can be seen from the table above, the molecular weight of polyethylene glycol selected in the two-phase extractant under this experimental condition has an effect on the extraction of dendrobium polysaccharides. The reason is that although the polyethylene glycol with a lower molecular weight has a lower viscosity, it has fewer functional groups such as hydroxyl groups, which reduces the extraction efficiency. Although the polyethylene glycol with a high molecular weight has more functional groups such as hydroxyl groups, its polarity is relatively small and has a higher viscosity, which also reduces the extraction efficiency. The polyethylene glycol with a medium molecular weight reaches a balance between the two, thus having a higher extraction efficiency. The ratio of polyethylene glycol to phosphate in the two-water extractant also affects the extraction efficiency. When the polyethylene glycol content is too low, the phosphate will cause the polysaccharide to enter the lower phase (phosphate solution phase) through ion action, reducing the extraction efficiency. When the polyethylene glycol content is too high, the viscosity of the system increases, hindering the diffusion and mass transfer of substances, and reducing the extraction efficiency.

[0125] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent changes made using the description of the present invention are also included in the patent protection scope of the present invention.

Claims

1. A method for extracting polysaccharides from Chinese medicinal materials, using Dendrobium officinale as raw material, characterized in that: The following steps are involved: S1: Wash, dry, crush and sieve the Dendrobium officinale to obtain 50-80 mesh Dendrobium officinale coarse powder; S2: adding the coarse powder of dendrobium to a buffer solution, stirring, and obtaining a suspension of dendrobium; S3: placing the dendrobium suspension in a 40kHz ultrasonic environment for 20-40 minutes, with the temperature controlled at 20°C-40°C; S4: placing the Dendrobium suspension treated in step S3 in a 300W microwave environment for 120-210 seconds; S5: adding the aqueous two-phase extractant to the Dendrobium suspension treated in step S4, stirring, mixing evenly, standing for 30 minutes, centrifuging for 5 minutes, and separating the aqueous two-phase; S6: collecting the upper layer liquid and the lower layer liquid, dialyzing, concentrating and drying the upper layer liquid to obtain Dendrobium polysaccharide.

2. A method for extracting polysaccharides from Chinese medicinal materials according to claim 1, characterized in that: The buffer solution in step S2 is a phosphate buffer solution with a pH of 7.0-7.4, and the solid-liquid ratio of the dendrobium crude powder to the phosphate buffer solution is 1:5-1:

10.

3. A method for extracting polysaccharides from Chinese medicinal materials according to claim 2, characterized in that: The phosphate buffer is made of sodium dihydrogen phosphate, disodium hydrogen phosphate and distilled water.

4. The method for extracting polysaccharides from Chinese medicinal materials according to claim 1, characterized in that: The two-phase aqueous extractant in step S5 is composed of polyethylene glycol and sodium dihydrogen phosphate, and the solid-liquid ratio of the two-phase aqueous extractant to the dendrobium crude powder is 1:20-1:

40.

5. A method for extracting polysaccharides from Chinese medicinal materials according to claim 4, characterized in that: The ratio of polyethylene glycol to phosphate in the double water extractant is 1:1-1:

4.

6. A method for extracting polysaccharides from Chinese medicinal materials according to claim 4 or 5, characterized in that: The molecular weight of the polyethylene glycol is between 2000-4000.

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