Extraction method and process optimization method of nettle polysaccharide in nettle

Abstract

The invention discloses an extraction method of nettle polysaccharide in nettle and a process optimization method, and belongs to the technical field of polysaccharide extraction. The method comprises the following steps: adding ethanol into dry rhizome powder of nettle, carrying out heating reflux treatment in a water bath, carrying out suction filtration, collecting filter residues, and volatilizing ethanol to obtain a degreased sample; performing hot water extraction on the degreased sample to obtain filtrate; and adding ethanol into the filtrate for alcohol precipitation, standing, separating to obtain a precipitate, and volatilizing the ethanol in the precipitate to dryness to obtain the nettle polysaccharide. According to the method, the blank of nettle polysaccharide extraction process research is filled, the nettle polysaccharide in nettle is extracted according to the explored extraction conditions, the extraction rate of the nettle polysaccharide can reach 10% or above, and a basis can be provided for new medicine research and application of the nettle polysaccharide.

Description

Technical Field

[0001] The invention belongs to the technical field of polysaccharide extraction, and particularly relates to a method for extracting nettle polysaccharides from urtica dioica and a process optimization method. Background Art

[0002] As an important class of biologically active substances, polysaccharides have a wide range of pharmacological effects. In the prior art, there are many methods for extracting polysaccharides, including ultrasonic-assisted extraction, enzymatic hydrolysis, microwave-assisted extraction, and water extraction. Ultrasonic-assisted extraction will affect the structure and molecular properties of polysaccharides due to its mechanical, thermal and cavitation effects; enzymatic hydrolysis is easy to inactivate the enzyme and the higher-order structure of polysaccharides may change due to the action of the enzyme; microwave-assisted extraction is not suitable for large-scale industrial production because the equipment required is expensive. Water extraction is widely used in the prior art because of its good economy, environmental protection and simple operation.

[0003] Urtica zayuensis CJChen is a plant of the Urticaceae Urticaceae Urticaceae, Urticales, dicotyledon class, mainly distributed in southeastern Tibet. In recent years, through in-depth research on Urticaceae plants, it was found that Urticaceae plants mainly contain chemical components such as polysaccharides, flavonoids, coumarins, lignans, volatile oils, etc. Modern pharmacology studies have shown that it has multiple pharmacological effects such as anti-inflammatory, anti-rheumatic, anti-prostatic hyperplasia, antibacterial, and analgesic. Urtica zayuensis polysaccharides may have unique biological activities, and research on its extraction process can provide a basis for the development of new drugs and health products. With the increasing demand for natural drugs and health products, research on the extraction process of urticaceae polysaccharides can provide new options to meet market demand, but there is no research on the water extraction method of urticaceae polysaccharides. How to use water extraction to extract the polysaccharide components in urticaceae to a greater extent is worth exploring. Summary of the invention

[0004] In view of the above problems, considering the reasons of simple operation and economy, the present invention uses response surface analysis to fit the experimental data with regression equations, establishes a continuous variable surface model, and proposes a method for extracting nettle polysaccharides from urtica dioica.

[0005] In a first aspect, the present invention provides a method for extracting urtica polysaccharides from Urtica dioica, comprising the following steps:

[0006] Add 95% ethanol to the dry rhizome powder of Urtica dioica, heat and reflux it in a water bath, then filter it, collect the residue and evaporate the ethanol to obtain a defatted sample;

[0007] The defatted sample is subjected to hot water extraction to obtain a filtrate;

[0008] Add ethanol to the filtrate for alcohol precipitation, let it stand for separation to obtain a precipitate, and evaporate the ethanol in the precipitate to obtain the urtica polysaccharide.

[0009] Furthermore, the extraction temperature during the hot water extraction process is 90-92°C, specifically 90°C, 91°C, 91.873°C, 92°C.

[0010] Furthermore, the extraction time in the hot water extraction process is 1.6-1.9 h, specifically 1.6 h, 1.7 h, 1.888 h, 1.9 h.

[0011] Furthermore, in the hot water extraction process, the solid-liquid ratio of the defatted sample to hot water is 19-21 mg:1 mL, specifically 19 mg:1 mL, 20 mg:1 mL, 20.475 mg:1 mL, and 21 mg:1 mL.

[0012] Furthermore, the number of hot water extractions is 1-3 times, specifically 1 time, 2 times, or 3 times.

[0013] Furthermore, the mass concentration of ethanol in the alcohol precipitation process is 80-81%, specifically 80%, 80.606% and 81%.

[0014] In a second aspect, the present invention provides a polysaccharide of Urtica dioica, which is extracted by the method described above.

[0015] In a third aspect, the present invention provides a process optimization method for extracting nettle polysaccharides from Urtica dioica, comprising the following steps:

[0016] The single factor experiment was used to determine the optimal solid-liquid ratio of defatted sample and hot water during hot water extraction, the optimal extraction time during hot water extraction, the optimal extraction temperature during hot water extraction, and the optimal ethanol concentration during alcohol precipitation, taking the extraction rate of urtica polysaccharide as an indicator.

[0017] Based on the optimal solid-liquid ratio of defatted sample and hot water during hot water extraction, the optimal extraction time during hot water extraction, the optimal extraction temperature during hot water extraction, and the optimal concentration of ethanol during alcohol precipitation determined by single factor experiments, the factors and factor level ranges in the response surface experiment were proposed;

[0018] Design response surface experiments based on the factors and factor level ranges of the proposed response surface experiments;

[0019] The extraction process of Urtica dioica polysaccharide was optimized based on the results of response surface experiment.

[0020] Further, the design of the response surface experiment according to the proposed optimal level and factor level of the response surface experiment comprises the following steps:

[0021] A quadratic multinomial regression model was established with the optimal solid-liquid ratio of the defatted sample and the hot water during the hot water extraction, the optimal extraction time during the hot water extraction, the optimal extraction temperature during the hot water extraction, and the optimal concentration of ethanol during the alcohol precipitation as independent variables and the extraction rate of Zayu Urtica polysaccharide as the response value;

[0022] Verifying and evaluating the quadratic polynomial regression model to select the optimal quadratic polynomial regression model;

[0023] Based on the optimal quadratic multinomial regression model, a response surface diagram and a contour diagram are respectively drawn based on the interaction of any two factors among the optimal solid-liquid ratio of the defatted sample and the hot water during the hot water extraction process, the optimal extraction time during the hot water extraction process, the optimal extraction temperature during the hot water extraction process, and the optimal concentration of ethanol during the alcohol precipitation process;

[0024] The optimal extraction conditions in the extraction method of Urtica dioica polysaccharide are determined according to the response surface diagram and the contour diagram.

[0025] Furthermore, the optimal extraction conditions in the extraction method of Urtica dioica polysaccharide are:

[0026] The solid-liquid ratio of the defatted sample and hot water during the hot water extraction process was 20.745:1, the extraction time during the hot water extraction process was 1.888 h, the extraction temperature during the hot water extraction process was 91.873° C., and the ethanol concentration during the alcohol precipitation process was 80.606%.

[0027] Beneficial effects of the present invention:

[0028] The present invention proposes a method for extracting urtica polysaccharides from Zayu urtica, which fills the gap in the research on the extraction process of urtica polysaccharides from Zayu urtica. According to the extraction conditions explored by the present invention, urtica polysaccharides from Zayu urtica are extracted, and the extraction rate of urtica polysaccharides can reach more than 10%, which can provide a basis for the pharmaceutical research and application of urtica polysaccharides.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A line graph showing the extraction rate of Urtica dioica polysaccharide from Urtica dioica at different extraction temperatures in an embodiment of the present invention is shown;

[0032] Figure 2 A line graph showing the extraction rate of nettle polysaccharides from Urtica dioica at different material-liquid ratios in an embodiment of the present invention is shown;

[0033] Figure 3 A line graph showing the extraction rate of nettle polysaccharides in Urtica dioica at different extraction times in an embodiment of the present invention is shown;

[0034] Figure 4 A line graph showing the extraction rate of Urtica dioica polysaccharide from Urtica dioica at different ethanol concentrations in an embodiment of the present invention is shown;

[0035] Figure 5 The response surface and contour diagram of the effects of extraction temperature and material-liquid ratio on the extraction rate of nettle polysaccharides in Zayu Urtica are shown in the embodiments of the present invention;

[0036] Figure 6 The response surface and contour map of the effects of extraction temperature and extraction time on the extraction rate of nettle polysaccharides in Zayu Urtica are shown in the embodiments of the present invention;

[0037] Figure 7 The response surface and contour map of the effects of extraction temperature and ethanol concentration on the extraction rate of urtica polysaccharides in Urtica dioica in the embodiment of the present invention are shown;

[0038] Figure 8 The response surface and contour map of the effects of the solid-liquid ratio and the extraction time on the extraction rate of nettle polysaccharides in Zayu Urtica are shown in the embodiments of the present invention;

[0039] Fig. 9 The response surface and contour map of the effects of the solid-liquid ratio and the ethanol concentration on the extraction rate of the urtica polysaccharide in the Zayu urtica in the embodiment of the present invention are shown;

[0040] Fig.10 The response surface and contour diagram of the effects of extraction time and ethanol concentration on the extraction rate of urtica polysaccharides from Urtica dioica in the embodiments of the present invention are shown. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Example 1

[0043] A method for extracting urtica polysaccharide from Zayu, comprising the following steps:

[0044] Step 1: weigh an appropriate amount of dried rhizomes of Urtica dioica, crush them, add 10 times the volume mass concentration of 95% ethanol, heat and reflux in a water bath at 80°C for 2h to perform degreasing treatment, then filter, collect the residue, evaporate the ethanol, and obtain a degreasing sample;

[0045] Step 2: Accurately weigh 10 g of the treated sample in step 1, add water to a beaker for hot water extraction, and obtain a filtrate;

[0046] Step 3: Add ethanol to the filtrate obtained in step 2 for alcohol precipitation. After standing overnight, centrifuge at 4000r / min for 10min to retain the precipitate. After the ethanol evaporates naturally, the crude polysaccharide of Urtica dioica is obtained.

[0047] The polysaccharide content was determined as follows:

[0048] (1) Accurately weigh 0.04 g of anthrone reagent into a beaker, slowly add 40 mL of 80% sulfuric acid along the wall of the beaker to dissolve, transfer to a brown reagent bottle, and store in a dark place for later use;

[0049] (2) Accurately weigh 10 mg of glucose standard dried to constant weight at 105°C, dissolve it in distilled water, transfer it to a 100 mL volumetric flask, make up to volume, shake well, and prepare a glucose standard solution with a concentration of 0.1 mg / mL for later use;

[0050] (3) Accurately pipette 0, 0.20, 0.40, 0.60, 0.80, and 1.00 mL of glucose standard solution into a stoppered test tube, dilute to 1 mL with distilled water, quickly add 4 mL of the prepared anthrone sulfuric acid reagent in an ice bath, shake well, heat in a boiling water bath for 10 min, take out, cool to room temperature, and measure the absorbance at a wavelength of 620 nm;

[0051] (4) Using the glucose concentration as the horizontal coordinate x and the absorbance as the vertical coordinate y for regression processing, the regression equation is y = 8.6063x + 0.051, R 2 =0.9967, linear range 0.021-0.105 mg / mL.

[0052] Calculate the extraction rate of nettle polysaccharides:

[0053]

[0054] Wherein: y represents the extraction rate of the urtica polysaccharide sample (%); C represents the concentration of the urtica polysaccharide sample (mg / mL); V represents the volume of the urtica polysaccharide sample (mL); and m represents the mass of the urtica polysaccharide sample (mg).

[0055] Example 2

[0056] The "four-factor five-level approach" was adopted to set four single-factor experiments, namely, extraction temperature (60°C, 70°C, 80°C, 90°C, 100°C), solid-liquid ratio (10:1, 15:1, 20:1, 25:1, 30:1), extraction time (1h, 1.5h, 2h, 2.5h, 3h) and ethanol concentration (70%, 75%, 80%, 85%, 90%). Urtica polysaccharide was extracted by the water extraction and alcohol precipitation method described in steps two and three of Example 1, and the extraction rate of urtica polysaccharide in urtica dioica was calculated at different variable parameters.

[0057] 1. Single factor test results

[0058] 1. Effect of different extraction temperatures on the extraction rate of Urtica dioica polysaccharides:

[0059] Accurately weigh 10 g of defatted Zayu nettle sample, place them in 250 mL conical flasks, fix the solid-liquid ratio to 15:1, extract twice, each time for 1.5 h, under the condition of 80% ethanol concentration, the extraction temperatures are (60°C, 70°C, 80°C, 90°C, 100°C), and calculate the nettle polysaccharide extraction rate according to the above steps. The results are as follows: Figure 1 shown.

[0060] Figure 1 The results showed that as the temperature increased, the extraction rate of urtica polysaccharides continued to increase, reaching the highest at 90°C, and then the extraction rate of urtica polysaccharides decreased. The reason may be that the high temperature will cause the urtica polysaccharides to degrade; therefore, the optimal extraction temperature was set at 90°C.

[0061] 2. Effect of different material-liquid ratios on the extraction rate of Urtica dioica polysaccharides:

[0062] Accurately weigh 10 portions of 10g defatted Zayu nettle sample, place them in 250mL conical flasks, fix the extraction temperature at 90℃, extract twice, each time for 1.5h, under the condition of 80% ethanol concentration, the solid-liquid ratio is (10:1, 15:1, 20:1, 25:1, 30:1), and calculate the nettle polysaccharide extraction rate according to the above steps. The results are as follows: Figure 2 shown.

[0063] Figure 2 The results showed that as the solid-liquid ratio increased, the osmotic pressure between the medicinal material tissue and the solution increased, causing the urtica polysaccharide to dissolve continuously. When the solid-liquid ratio was 20:1, the extraction rate of urtica polysaccharide was the highest. When the solid-liquid ratio continued to increase, the extraction rate of urtica polysaccharide began to decrease. At this time, due to the continuous increase of solvent, other impurities were gradually dissolved; therefore, the optimal solid-liquid ratio was set at 20:1.

[0064] 3. Effect of different extraction time on the extraction rate of Urtica dioica polysaccharides:

[0065] Accurately weigh 10 portions of 10g defatted Zayu nettle sample, place them in 250mL conical flasks respectively, fix the extraction temperature at 90℃, the solid-liquid ratio at 15:1, extract twice, and the ethanol concentration at 80%. The extraction time is (1h, 1.5h, 2h, 2.5h, 3h) respectively. Calculate the nettle polysaccharide extraction rate according to the above steps. The results are as follows: Figure 3 shown.

[0066] Figure 3 The results showed that as the extraction time increased, the extraction rate of nettle polysaccharides first increased and then decreased. When the extraction time was 2 hours, the extraction rate of nettle polysaccharides reached the highest. When the extraction time was extended, the nettle polysaccharides might be degraded under long-term high temperature conditions, resulting in a decrease in the extraction rate. Therefore, the optimal extraction time was set at 2 hours.

[0067] 4. Effect of different ethanol concentrations on the extraction rate of Urtica dioica polysaccharides:

[0068] Accurately weigh 10 portions of 10g defatted Zayu nettle sample and place them in 250mL conical flasks respectively. Fix the extraction temperature at 90℃, the solid-liquid ratio at 15:1, extract twice, each time for 1.5h, and the ethanol concentrations are (70%, 75%, 80%, 85%, 90%) respectively. Calculate the nettle polysaccharide extraction rate according to the above steps. The results are as follows: Figure 4 shown.

[0069] Figure 4 The results showed that when the ethanol concentration reached 80%, the urtica polysaccharide was basically precipitated completely, so the optimal ethanol concentration was set at 80%.

[0070] Example 3

[0071] The results obtained from the single factor experiment in Example 2 were proposed as the optimal level. The factor levels and coding settings are shown in Table 1. A response surface experiment was conducted with the optimal solid-liquid ratio of defatted sample and hot water during hot water extraction, the optimal extraction time during hot water extraction, the optimal extraction temperature during hot water extraction, and the optimal concentration of ethanol during alcohol precipitation as independent variables and the extraction rate of Zayu Urtica polysaccharide as the response value.

[0072] Table 1 Factor levels

[0073]

[0074] Design-Expert13 software was used to carry out a four-factor three-level experimental design according to the Box-Benhnken design principle. The experimental scheme and response surface results are shown in Table 2:

[0075] Table 2 Response surface experimental design and results

[0076]

[0077]

[0078] Desgin-Expert13 software was used to perform multivariate regression fitting on the experimental data, and the quadratic multinomial regression model of the extraction rate Y of nettle polysaccharides in Zayu nettle was obtained:

[0079] Y=10.63+0.1587A+0.0997B-0.0931C+0.0823D+0.0933AB+0.0347AC+0.2672AD-0.3080BC-0.0492BD-0.0055CD-0.5261A 2 -0.6059B 2 -0.2963C 2 -0.5220D 2 , R 2 =0.9409.

[0080] The results of variance analysis are shown in Table 3:

[0081] Table 3 Results of variance analysis of regression equation

[0082]

[0083]

[0084] In Table 3, ** indicates extremely significant (P < 0.01), * indicates significant (P < 0.05). From the variance analysis results in Table 4, it can be seen that the model P value is < 0.01, which is extremely significant; the P value of the lack of fit term is > 0.05, which is not significant. This shows that the model has a good fit and the experimental error is small, indicating that it is feasible to use the response surface methodology to optimize the extraction process of Urtica dioica polysaccharides in Zayu, which is of reference value. The order of significance of the influence of each factor on the response value is extraction temperature > solid-liquid ratio > extraction time > ethanol concentration.

[0085] According to the analysis of Desgin-Expert13 software, the effects of any two factors interacting on the extraction rate of urtica polysaccharides in Zayu urtica were analyzed and compared, and the response surface diagram and contour diagram were drawn as shown in Figure 5-10 As shown, the left side is the response surface diagram and the right side is the contour diagram. Figure 5 The response surface and contour diagram of the effects of extraction temperature and material-liquid ratio on the extraction rate of urticaria polysaccharides from Zayu Urtica are shown in Figure 2. Figure 6 The response surface and contour diagram of the effects of extraction temperature and extraction time on the extraction rate of nettle polysaccharides. Figure 7are the response surfaces and contour lines for the effects of extraction temperature and ethanol concentration on the extraction rate of urtica polysaccharides. Figure 8 The response surface and contour diagram of the effects of solid-liquid ratio and extraction time on the extraction rate of nettle polysaccharides. Fig. 9 The response surface and contour diagram of the effects of solid-liquid ratio and ethanol concentration on the extraction rate of nettle polysaccharides. Fig.10 The response surface and contour diagram of the effects of extraction time and ethanol concentration on the extraction rate of nettle polysaccharides. In the figure, the larger the slope of the response surface, the more sensitive the response value is to the change of the influencing factors.

[0086] The optimal extraction conditions were determined by analysis using Design-Expert13.0 software: extraction temperature was 91.873°C, solid-liquid ratio was 20.745:1, extraction time was 1.888h, and ethanol concentration was 80.606%. Under these conditions, the extraction rate of Zayu Urtica polysaccharide was 10.667%.

[0087] Example 4

[0088] According to the optimal extraction conditions determined in Example 3, combined with the actual operating conditions, the final optimized conditions were determined to be an extraction temperature of 90° C., a solid-liquid ratio of 20:1, an extraction time of 2 h, and an ethanol concentration of 80%.

[0089] The specific extraction process is as follows:

[0090] Step 1: Weigh the dried rhizomes of Urtica dioica and grind them, add 10 times the volume mass concentration of 95% ethanol, heat and reflux in a water bath at 80°C for 2h to perform degreasing treatment, then filter, collect the filter residue, evaporate the ethanol, and obtain a degreasing sample;

[0091] Step 2: Accurately weigh 10 g of the defatted sample in step 1, add 500 mL of water into a beaker for hot water extraction once, the extraction temperature is 90°C, and obtain a filtrate;

[0092] Step 3: Add 80% ethanol to the filtrate obtained in step 2 for alcohol precipitation. After standing overnight, centrifuge at 4000 r / min for 10 min to collect the precipitate. After the ethanol evaporates naturally, the crude polysaccharide of Urtica dioica is obtained.

[0093] The polysaccharide content determination method of Example 1 was used to determine that the extraction rate of urtica polysaccharides in Urtica dioica in this example was 10.12%, which was very close to the predicted value of 10.667%.

[0094] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting nettle polysaccharides from Urtica dioica, characterized in that: The following steps are involved: Add ethanol to the dry rhizome powder of Urtica dioica, heat and reflux it in a water bath, then filter it, collect the filter residue and evaporate the ethanol to obtain a defatted sample; The defatted sample is subjected to hot water extraction to obtain a filtrate; Add ethanol to the filtrate for alcohol precipitation, let it stand for separation to obtain a precipitate, and evaporate the ethanol in the precipitate to obtain the urtica polysaccharide.

2. The method for extracting nettle polysaccharides from Zayu nettle according to claim 1, characterized in that: The extraction temperature during the hot water extraction process is 90-92°C.

3. The method for extracting nettle polysaccharides from Zayu nettle according to claim 1, characterized in that: The extraction time during the hot water extraction process is 1.6-1.9 hours.

4. The method for extracting nettle polysaccharides from Zayu nettle according to claim 1, characterized in that: The solid-liquid ratio of the defatted sample to hot water during the hot water extraction process is 19-21 mg:1 mL.

5. The method for extracting nettle polysaccharides from Zayu nettle according to claim 1, characterized in that: The number of hot water extractions during the hot water extraction process is 1-3 times.

6. The method for extracting nettle polysaccharides from Zayu nettle according to claim 1, characterized in that: The mass concentration of ethanol in the alcohol precipitation process is 80-81%.

7. A Zayu Urtica polysaccharide, characterized in that The method is extracted by any one of claims 1 to 6.

8. A process optimization method for extracting nettle polysaccharides from Zayu nettle as claimed in claims 1-6, characterized in that: The following steps are involved: The single factor experiment was used to determine the optimal solid-liquid ratio of defatted sample and hot water during hot water extraction, the optimal extraction time during hot water extraction, the optimal extraction temperature during hot water extraction, and the optimal ethanol concentration during alcohol precipitation, taking the extraction rate of urtica polysaccharide as an indicator. Based on the optimal solid-liquid ratio of defatted sample and hot water during hot water extraction, the optimal extraction time during hot water extraction, the optimal extraction temperature during hot water extraction, and the optimal concentration of ethanol during alcohol precipitation determined by single factor experiments, the factors and factor level ranges in the response surface experiment were proposed; Design response surface experiments based on the factors and factor level ranges of the proposed response surface experiments; The extraction process of Urtica dioica polysaccharide was optimized based on the results of response surface experiment.

9. The process optimization method for extracting nettle polysaccharides from Zayu nettle according to claim 8, characterized in that: The response surface experiment designed according to the proposed optimal level and factor level of the response surface experiment comprises the following steps: A quadratic multinomial regression model was established with the optimal solid-liquid ratio of the defatted sample and the hot water during the hot water extraction, the optimal extraction time during the hot water extraction, the optimal extraction temperature during the hot water extraction, and the optimal concentration of ethanol during the alcohol precipitation as independent variables and the extraction rate of Zayu Urtica polysaccharide as the response value; Verifying and evaluating the quadratic polynomial regression model to select the optimal quadratic polynomial regression model; Based on the optimal quadratic multinomial regression model, a response surface diagram and a contour diagram are respectively drawn based on the interaction of any two factors among the optimal solid-liquid ratio of the defatted sample and the hot water during the hot water extraction process, the optimal extraction time during the hot water extraction process, the optimal extraction temperature during the hot water extraction process, and the optimal concentration of ethanol during the alcohol precipitation process; The optimal extraction conditions in the extraction method of Urtica dioica polysaccharide are determined according to the response surface diagram and the contour diagram.

10. The process optimization method for extracting nettle polysaccharides from Zayu nettle according to claim 9, characterized in that: The optimal extraction conditions in the extraction method of Urtica dioica polysaccharide are: The solid-liquid ratio of the defatted sample and hot water during the hot water extraction process was 20.745:1, the extraction time during the hot water extraction process was 1.888 h, the extraction temperature during the hot water extraction process was 91.873° C., and the ethanol concentration during the alcohol precipitation process was 80.606%.

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