Preparation method and application of high-activity selenized tremella polysaccharide

Abstract

The invention discloses a preparation method of high-activity selenized tremella polysaccharide, and belongs to the technical field of deep processing of edible mushrooms. According to the method disclosed by the invention, fresh frozen tremella pedicels are taken as a raw material, an ultrasonic-microwave synergistic auxiliary nitric acid-sodium selenite selenylation system is adopted, refined tremella polysaccharide is subjected to selenylation reaction, the combination efficiency of polysaccharide and selenium is remarkably improved through a physical field synergistic effect, and high-activity selenylation tremella polysaccharide is prepared; according to the preparation method, the ultrasonic-microwave synergistic enhancement technology and the nitric acid-sodium selenite selenylation method are combined for the first time, the technical bottleneck of low polysaccharide selenylation efficiency is overcome, the selenium content in the prepared selenylation tremella polysaccharide is as high as 30000-50000 mg / kg, the selenylation tremella polysaccharide has remarkable blood sugar reducing activity, and an innovative raw material is provided for development of blood sugar reducing functional food and drugs.

Description

Technical Field

[0001] The present invention specifically relates to a preparation method and application of highly active selenized Tremella fuciformis polysaccharide, belonging to the technical field of edible fungus deep processing. Background Art

[0002] Tremella, also known as white fungus, is a fungus that is both medicinal and edible. The tremella pedicles, as a by-product of tremella processing, account for about 10-20% of the mass of the fruiting body and are often discarded or used at a low value. Its main pharmacological component is tremella polysaccharide, which has immune-regulating, anti-tumor and lipid-lowering effects. Selenium modification is an effective modification method to enhance the antioxidant and blood sugar-lowering biological activity of polysaccharides, and therefore has broad application prospects in functional foods, health products and medicine.

[0003] Existing technologies mostly use dried Tremella fuciformis as raw material to prepare selenized Tremella fuciformis polysaccharides, which is cost-effective but has low benefits. Therefore, a method for preparing selenized Tremella fuciformis polysaccharides with high selenium content and biological activity using fresh Tremella fuciformis stems as raw materials is developed. This method can not only realize the resource utilization of by-products, improve the comprehensive utilization value of Tremella fuciformis resources, and promote the development of Tremella fuciformis deep processing industry, but also provide a new type of highly active selenized polysaccharide product for functional foods, health products and pharmaceutical fields. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a method for preparing highly active selenized Tremella fuciformis polysaccharide, which uses fresh frozen Tremella fuciformis pedicles as raw materials and improves the polysaccharide extraction process to increase the low selenization efficiency of the polysaccharide.

[0005] The technical solution adopted in the present invention is as follows:

[0006] The invention provides a preparation method of highly active selenized tremella polysaccharide. The method comprises the following steps: taking fresh frozen tremella pedicles as raw materials, adopting an ultrasound-microwave synergistically assisted nitric acid-sodium selenite selenization system, performing a selenization reaction on the refined tremella polysaccharide, improving the binding efficiency of the polysaccharide and selenium, and preparing highly active selenized tremella polysaccharide.

[0007] Furthermore, the preparation method of the highly active selenized Tremella fuciformis polysaccharide comprises the following steps:

[0008] Fresh frozen Tremella fuciformis pedicles were used as raw materials, and crude Tremella fuciformis polysaccharide was extracted by hot water extraction method, and refined polysaccharide was obtained by sieving, ethanol precipitation and vacuum freeze drying.

[0009] The treated refined polysaccharide is dissolved in dilute nitric acid, sodium selenite and barium chloride are added, and selenization reaction is carried out for 2 to 6 hours under intermittent ultrasound-microwave synergistic enhancement conditions to obtain a reaction solution;

[0010] The pH value of the reaction solution is adjusted to 6-7, and then the excess barium ions in the reaction solution are removed and dialyzed through a dialysis bag, and the retentate is collected. The retentate is concentrated, precipitated, and vacuum-freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

[0011] Furthermore, in the ultrasound-microwave synergistic assistance, the microwave power is 60-600 W, the ultrasound power is 60-600 W, and the microwave is 25-60 min / ultrasound is 5-20 min in a cycle.

[0012] Furthermore, in the above steps, the mass ratio of the refined polysaccharide to sodium selenite is 1:0.4 to 1:2.4, and the mass ratio of sodium selenite to barium chloride is 1:0.8 to 1:2.8.

[0013] Furthermore, the pH of the reaction solution is adjusted using 1-1.2 mol / L sodium bicarbonate.

[0014] The present invention also provides use of the selenized Tremella fuciformis polysaccharide prepared according to the preparation method in preparing blood sugar-lowering drugs.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention utilizes fresh frozen white fungus pedicles, a low-cost, easily available raw material, to achieve high-value and high-quality resource utilization. At the same time, according to the high viscosity and shear-thinning properties of white fungus polysaccharide at low concentrations (the viscosity value of 0.2% concentration exceeds 100mPa·s, and it is a non-Newtonian fluid), the ultrasound-microwave synergistic technology is creatively applied to the selenization modification process of white fungus polysaccharide. The ultrasonic cavitation effect can destroy the hydrogen bonds of the polysaccharide molecular chains, reduce the viscosity of the polysaccharide solution, and increase the exposure of active sites, while microwave heating can quickly and evenly provide energy. The synergistic effect of the two can significantly shorten the reaction time, improve the modification efficiency of white fungus polysaccharide by selenization reaction, and overcome the shortcomings of traditional selenization methods such as long reaction time and low efficiency.

[0017] 2. The main chain of Tremella polysaccharide is composed of β-(1→3)-D-glucan, and the side chain contains β-(1→6)-glucosidic bond and a small amount of mannose, xylose, etc. This loose spiral structure with high branching degree and rich in hydroxyl groups is more susceptible to selenization reaction than linear polysaccharides such as starch and cellulose, and can form a stable three-dimensional selenate bond. In addition, compared with other common edible fungi polysaccharides, its free hydroxyl density is higher, and it also provides more selenization sites for selenization modification. Therefore, the present invention has a high adaptability to the selenization reaction using Tremella polysaccharide as raw material, because its reaction conditions are relatively mild, which can inhibit the excessive oxidation of Na2SeO3, while chitosan and the like need to react under high temperature conditions, which can easily lead to -SeO3 - Reduction to red elemental selenium will lead to a decrease in selenium utilization, a reduction in effective reactants, and a decrease in the selenization rate.

[0018] 3. Selenized Tremella fuciformis polysaccharide with a total selenium content of up to 30,000-50,000 mg / kg was successfully prepared by the method provided by the present invention, and the total selenium content was significantly higher than that of conventional selenized polysaccharide products.

[0019] 4. The inhibition rate of α-glucosidase in vitro by the selenized Tremella polysaccharide prepared by the present invention can be as high as 80% or more (IC 50 ≤5.00 mg / mL), and showed a significant hypoglycemic effect in a diabetic mouse model induced by streptozotocin. The hypoglycemic activity was much better than that of unselenized Tremella polysaccharide and similar commercially available selenium polysaccharide products, and the effect was stable. Therefore, the selenized Tremella polysaccharide prepared by the present invention can be used as an efficient and safe natural hypoglycemic functional factor, and is widely used in the fields of hypoglycemic drugs, functional foods, special medical purpose formula foods and health products, with significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the preparation method of the highly active selenized Tremella fuciformis polysaccharide of the present invention;

[0021] Figure 2 The α-amylase inhibition rate of the selenized Tremella fuciformis polysaccharide prepared in the examples of the present invention is shown, wherein ac represents Examples 1-3 respectively.

[0022] Figure 3 It shows that the selenized Tremella polysaccharide prepared in the embodiment of the present invention reaches IC 50 The concentration at that time. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0024] In order to better understand the present invention, the present invention is further described below through examples. The examples are only used to explain the present invention and do not constitute any limitation to the present invention.

[0025] Unless otherwise specified, the materials and reagents used in the following examples are commercially available. The quantitative tests in the following examples were performed in triplicate, and the results were averaged. The experimental methods in the following examples are all conventional methods, unless otherwise specified.

[0026] The reaction conditions for extracting Tremella crude polysaccharide by hot water extraction in the following examples are as follows:

[0027] The solid-liquid ratio of fresh frozen Tremella fuciformis pedicles to hot water is 1:8-1:14 g / mL, and extraction is carried out at 70-100°C for 25-60 min. After the extraction reaction, the mixture is sieved through a 60-100 mesh sieve and precipitated with alcohol at 0-5°C for 12-36 h (final ethanol concentration is 60%-80%).

[0028] Example 1

[0029] like Figure 1 As shown, this embodiment provides a method for preparing highly active selenized Tremella fuciformis polysaccharide, comprising the following steps:

[0030] Fresh frozen Tremella fuciformis pedicles were used as raw materials, added to pure water, the material-liquid ratio of the raw materials to pure water was 1:8 (g / mL), the extraction temperature was 70°C, and the extraction time was 60 min. The reaction solution obtained was Tremella fuciformis crude polysaccharide, the reaction solution was sieved with 60 mesh to obtain a filtrate, ethanol was added to a final concentration of 60%, the precipitation temperature was 0°C, and the precipitation time was 12 h; after removing the ethanol, water was added to dissolve, and the mixture was placed in a -15°C refrigerator for pre-freezing overnight, and then dried in a vacuum freeze dryer to obtain Tremella fuciformis refined polysaccharide, which was stored in a 4°C refrigerator away from light;

[0031] 1.0 g of the treated refined polysaccharide was weighed and dissolved in 250 mL of dilute nitric acid (0.2%, v / v), and stirred at room temperature for 30 min to completely dissolve the refined polysaccharide; 1.0 g of sodium selenite and 1.2 g of barium chloride were added, and microwave-assisted heating was performed to 35° C. at a microwave power of 60 W. Intermittent ultrasonic treatment was performed at the same time, with ultrasonication for 5 min every 25 min at an ultrasonic power of 60 W, and the entire reaction time was 6 h to obtain a reaction solution;

[0032] After the reaction, 1.0 mol / L sodium bicarbonate solution was used to adjust the pH of the reaction solution to 6-7, and sodium sulfite was added to remove excess Ba in the solution. 2+ Afterwards, the mixture was centrifuged at a speed of 10,000 r / min for 10 minutes, the supernatant was collected, and dialyzed in ultrapure water (molecular weight cutoff 3.0 kDa) for 72 hours. The retentate was collected, concentrated, precipitated, and vacuum freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

[0033] Example 2

[0034] This embodiment provides a method for preparing highly active selenized Tremella fuciformis polysaccharide, comprising the following steps:

[0035] Fresh frozen Tremella fuciformis pedicles were used as raw materials, added to pure water, the raw material to pure water ratio was 1:12 (g / mL), the extraction temperature was 100°C, and the extraction time was 25 minutes. The reaction solution obtained was Tremella fuciformis crude polysaccharide, the reaction solution was sieved with 100 mesh to obtain a filtrate, ethanol was added to a final concentration of 80%, the precipitation temperature was 5°C, and the precipitation time was 36 hours; after removing the ethanol, water was added to dissolve, and the mixture was placed in a -15°C refrigerator for pre-freezing overnight, and then dried in a vacuum freeze dryer to obtain Tremella fuciformis refined polysaccharide, which was stored in a 4°C refrigerator away from light;

[0036] 1.0 g of the treated refined polysaccharide was weighed and dissolved in 50 mL of dilute nitric acid (2.0%, v / v), and stirred at room temperature for 30 min to completely dissolve the refined polysaccharide; 1.6 g of sodium selenite and 1.0 g of barium chloride were added, and microwave-assisted heating was performed to 100° C. at a microwave power of 60 W, while intermittent ultrasonic treatment was performed at 600 W for 20 min every 60 min, and the overall reaction time was 2 h to obtain a reaction solution;

[0037] After the reaction, 1.2 mol / L sodium bicarbonate solution was used to adjust the pH of the reaction solution to 6-7, and sodium sulfite was added to remove excess Ba in the solution. 2+ Afterwards, the mixture was centrifuged at a speed of 10,000 r / min for 10 minutes, the supernatant was collected, and dialyzed in ultrapure water (molecular weight cutoff 3.5 kDa) for 48 hours. The retentate was collected, concentrated, precipitated, and vacuum freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

[0038] Example 3

[0039] This embodiment provides a method for preparing highly active selenized Tremella fuciformis polysaccharide, comprising the following steps:

[0040] Fresh frozen Tremella fuciformis pedicles are used as raw materials, added to pure water, the raw material to pure water ratio is 1:10 (g / mL), the extraction temperature is 85°C, the extraction time is 45 minutes, and the reaction solution obtained is Tremella fuciformis crude polysaccharide. The reaction solution is sieved through 80 mesh to obtain a filtrate, ethanol is added to a final concentration of 70%, the precipitation temperature is 3°C, and the precipitation time is 24 hours; after removing the ethanol, water is added to dissolve, and the product is placed in a -15°C refrigerator for pre-freezing overnight, and then dried in a vacuum freeze dryer to obtain Tremella fuciformis refined polysaccharide, which is stored in a 4°C refrigerator away from light;

[0041] 1.0 g of the treated refined polysaccharide was weighed and dissolved in 75 mL of dilute nitric acid (1.4%, v / v), and stirred at room temperature for 30 min to completely dissolve the refined polysaccharide; 2.0 g of sodium selenite and 2.0 g of barium chloride were added, and microwave-assisted heating was performed to 60° C. at a microwave power of 200 W. Intermittent ultrasonic treatment was performed at the same time, with ultrasonication for 10 min every 45 min at an ultrasonic power of 360 W, and the overall reaction time was 4 h to obtain a reaction solution;

[0042] After the reaction, 1.0 mol / L sodium bicarbonate solution was used to adjust the pH of the reaction solution to 6-7, and sodium sulfite was added to remove excess Ba in the solution. 2+ Afterwards, the mixture was centrifuged at a speed of 10,000 r / min for 10 minutes, the supernatant was collected, and dialyzed in ultrapure water (molecular weight cutoff 3.5 kDa) for 36 hours. The retentate was collected, concentrated, precipitated, and vacuum freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

[0043] Comparative Example 1

[0044] This comparative example provides a method for preparing selenized Tremella fuciformis polysaccharide, comprising the following steps:

[0045] Fresh frozen Tremella fuciformis pedicles were used as raw materials, added to pure water, the material-liquid ratio of the raw materials to pure water was 1:8 (g / mL), the extraction temperature was 70°C, and the extraction time was 60 min. The reaction solution obtained was Tremella fuciformis crude polysaccharide, the reaction solution was sieved with 60 mesh to obtain a filtrate, ethanol was added to a final concentration of 60%, the precipitation temperature was 0°C, and the precipitation time was 12 h; after removing the ethanol, water was added to dissolve, and the mixture was placed in a -15°C refrigerator for pre-freezing overnight, and then dried in a vacuum freeze dryer to obtain Tremella fuciformis refined polysaccharide, which was stored in a 4°C refrigerator away from light;

[0046] 1.0 g of the treated refined polysaccharide was weighed and dissolved in 250 mL of dilute nitric acid (0.2%, v / v), and stirred at room temperature for 30 min to completely dissolve the refined polysaccharide; 1.0 g of sodium selenite and 1.2 g of barium chloride were added, and the mixture was heated to 35° C. in a constant temperature water bath. The total reaction time was 6 h to obtain a reaction solution;

[0047] After the reaction, the pH value of the reaction solution was adjusted to 6-7 using 1.0 mol / L sodium bicarbonate solution, and sodium sulfite was added to remove excess Ba2+ in the solution. The solution was then centrifuged at a speed of 10,000 r / min for 10 minutes, and the supernatant was collected and dialyzed in ultrapure water (molecular weight cutoff 3.0 kDa) for 72 hours. The retentate was collected, concentrated, precipitated, and vacuum freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

[0048] Comparative Example 2

[0049] This comparative example provides a method for preparing selenized Tremella fuciformis polysaccharide, comprising the following steps:

[0050] Fresh frozen Tremella fuciformis pedicles were used as raw materials, added to pure water, the raw material to pure water ratio was 1:12 (g / mL), the extraction temperature was 100°C, and the extraction time was 25 minutes. The reaction solution obtained was Tremella fuciformis crude polysaccharide, the reaction solution was sieved with 100 mesh to obtain a filtrate, ethanol was added to a final concentration of 80%, the precipitation temperature was 5°C, and the precipitation time was 36 hours; after removing the ethanol, water was added to dissolve, and the mixture was placed in a -15°C refrigerator for pre-freezing overnight, and then dried in a vacuum freeze dryer to obtain Tremella fuciformis refined polysaccharide, which was stored in a 4°C refrigerator away from light;

[0051] 1.0 g of the treated refined polysaccharide was weighed and dissolved in 50 mL of dilute nitric acid (2.0%, v / v), and stirred at room temperature for 30 min to completely dissolve the refined polysaccharide. 1.6 g of sodium selenite and 1.0 g of barium chloride were added, and microwave-assisted heating was performed at 100° C., the microwave power was 60 W, and the total reaction time was 2 h to obtain a reaction solution.

[0052] After the reaction, the pH value of the reaction solution was adjusted to 6-7 using 1.2 mol / L sodium bicarbonate solution, and sodium sulfite was added to remove excess Ba2+ in the solution. The solution was then centrifuged at a speed of 10,000 r / min for 10 minutes, and the supernatant was collected and dialyzed in ultrapure water (molecular weight cutoff 3.5 kDa) for 48 hours. The retentate was collected, concentrated, precipitated, and vacuum freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

[0053] Comparative Example 3

[0054] This comparative example provides a method for preparing selenized Tremella fuciformis polysaccharide, comprising the following steps:

[0055] Fresh frozen Tremella fuciformis pedicles are used as raw materials, added to pure water, the raw material to pure water ratio is 1:10 (g / mL), the extraction temperature is 85°C, the extraction time is 45 minutes, and the reaction solution obtained is Tremella fuciformis crude polysaccharide. The reaction solution is sieved through 80 mesh to obtain a filtrate, ethanol is added to a final concentration of 70%, the precipitation temperature is 3°C, and the precipitation time is 24 hours; after removing the ethanol, water is added to dissolve, and the product is placed in a -15°C refrigerator for pre-freezing overnight, and then dried in a vacuum freeze dryer to obtain Tremella fuciformis refined polysaccharide, which is stored in a 4°C refrigerator away from light;

[0056] 1.0 g of the treated refined polysaccharide was weighed and dissolved in 75 mL of dilute nitric acid (1.4%, v / v), and stirred at room temperature for 30 min to completely dissolve the refined polysaccharide. 2.0 g of sodium selenite and 2.0 g of barium chloride were added, and the temperature was 60° C., the ultrasonic power was 360 W, and the total reaction time was 4 h to obtain a reaction solution.

[0057] After the reaction, the pH of the reaction solution was adjusted to 6-7 using 1.0 mol / L sodium bicarbonate solution, and sodium sulfite was added to remove excess Ba2+ in the solution. The solution was then centrifuged at a speed of 10,000 r / min for 10 minutes, and the supernatant was collected and dialyzed in ultrapure water (molecular weight cutoff 3.5 kDa) for 36 hours. The retentate was collected, concentrated, precipitated, and vacuum freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

[0058] Example 4

[0059] The corresponding selenized Tremella fuciformis polysaccharides and conventional Tremella fuciformis polysaccharides were prepared by the methods of Examples 1-3 and Comparative Examples 1-3 for comparison. The organic selenium and total selenium contents were detected by ICP-MS. The results are shown in Table 1.

[0060] Table 1 Comparison of selenium content in selenized Tremella fuciformis polysaccharides prepared by different processing methods

[0061]

[0062]

[0063] As can be seen from Table 1, compared with the traditional selenization method and the selenized Tremella fuciformis polysaccharide prepared with the assistance of single microwave or ultrasound, the selenized Tremella fuciformis polysaccharide prepared by the method of the present invention can significantly increase the organic selenium content, total selenium content and the mass percentage of organic selenium in total selenium.

[0064] The present invention uses an ultrasound-microwave assisted nitric acid-sodium selenite selenization system to organically combine selenium with Tremella polysaccharide to obtain selenized Tremella polysaccharide. As the concentration of polysaccharide increases, its α-amylase inhibition rate also increases. Figure 2 As shown, the highest inhibition rate of Tremella polysaccharide is 58.10%; the highest inhibition rate of Example 1 is 77.69%; the highest inhibition rate of Example 2 is 80.33%; and the highest inhibition rate of Example 3 is 87.87%.

[0065] The inhibitory effect of selenized Tremella fuciformis polysaccharide is better than that of Tremella fuciformis polysaccharide. Figure 3 As shown, Tremella polysaccharide reached IC 50 The concentration at this time is 7.88 mg / mL; Example 1 reaches IC 50 The concentration is 4.30 mg / mL; Example 2 reaches IC 50 The concentration at this time is 3.77 mg / mL; Example 3 reaches IC 50 The concentration at this time was 2.73 mg / mL.

[0066] Combine Figure 2 、 Figure 3As shown in Table 1, selenized Tremella fuciformis polysaccharide has inhibitory activity on α-amylase, and the inhibitory effect of selenized Tremella fuciformis polysaccharide is better than that of Tremella fuciformis polysaccharide. The higher the selenium content, the better the effect.

[0067] Example 5

[0068] In this example, selenized Tremella polysaccharide prepared according to the method for preparing highly active selenized polysaccharide provided by the present invention is used to prepare a hypoglycemic drug.

[0069] Mouse experiments:

[0070] This experiment tested the effects of selenized Tremella fuciformis polysaccharide on fasting blood glucose and oral glucose tolerance in diabetic mice, as follows:

[0071] Experimental design

[0072] C57BL / 6J mice aged 6 to 8 weeks and of similar weight were selected, with half male and half female in each group. Adaptive feeding was performed for one week: a standard day / night cycle (12h:12h) was maintained at a temperature of 20-26°C and a humidity of 50%-70%. The mice were randomly divided into five groups (n=10): a normal control group (basic diet + normal saline), a model group (high-sugar, high-fat diet + normal saline), a positive control group (high-sugar, high-fat diet + metformin 100 mg / kg), a blank control group (high-sugar, high-fat diet + Tremella fuciformis polysaccharide), and Example 3 (high-sugar, high-fat diet + selenized Tremella fuciformis polysaccharide). Eight weeks later, mice in the model group were injected with streptozotocin (STZ, 50 mg / kg), while mice in the normal control group were injected with the same dose of citric acid buffer solution for 5 consecutive days. One week after the intraperitoneal injection, the mice were fasted for 12 hours without food or water. Blood was collected by tail-cutting, and fasting blood glucose was measured using a human blood glucose meter. A fasting blood glucose of ≥11.1 mmol / L was considered a successful model.

[0073] Oral glucose tolerance test (OGTT)

[0074] All mice were fasted overnight (more than 12 hours) before the oral glucose tolerance test. Each group of mice was gavaged with glucose (1.5 g / kg), and the blood glucose levels at 0, 30, 60, 90, 120, and 180 minutes were measured using a blood glucose meter. The area under the curve (AUC) was calculated. OGTT ), the formula is as follows:

[0075] AUG OGTT =(0.5×E1+E2+E3+E4+E5+0.5×E6) / 30

[0076] Where: E1~E6 are blood glucose values ​​at 0, 30, 60, 90, 120 and 180 minutes respectively.

[0077] The results are shown in Table 2:

[0078] Table 2 Effects of selenized Tremella fuciformis polysaccharide on blood glucose in diabetic mice

[0079]

[0080] As can be seen from Table 2, Example 3 can significantly inhibit the increase of fasting blood sugar and improve impaired glucose tolerance compared with the blank group, and is an efficient selenium polysaccharide supplement for lowering blood sugar.

[0081] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing highly active selenized Tremella fuciformis polysaccharide, characterized in that: Fresh frozen Tremella fuciformis stems were used as raw materials, and the refined Tremella fuciformis polysaccharide was selenized by ultrasound-microwave assisted nitric acid-sodium selenite selenization system to obtain highly active selenized Tremella fuciformis polysaccharide.

2. The method for preparing highly active selenized Tremella fuciformis polysaccharide according to claim 1, wherein The following steps are involved: Fresh frozen Tremella fuciformis pedicles were used as raw materials, and crude Tremella fuciformis polysaccharide was extracted by hot water extraction method, and refined polysaccharide was obtained by sieving, ethanol precipitation and vacuum freeze drying. The treated refined polysaccharide is dissolved in dilute nitric acid, sodium selenite and barium chloride are added, and selenization reaction is carried out for 2 to 6 hours under intermittent ultrasound-microwave synergistic enhancement conditions to obtain a reaction solution; The pH value of the reaction solution is adjusted to 6-7, and then the excess barium ions in the reaction solution are removed and dialyzed through a dialysis bag, and the retentate is collected. The retentate is concentrated, precipitated, and vacuum-freeze-dried to obtain highly active selenized Tremella fuciformis polysaccharide.

3. The method for preparing highly active selenized Tremella fuciformis polysaccharide according to claim 1 or 2, wherein: In the ultrasound-microwave synergistic assistance, the microwave power is 60-600W, the ultrasound power is 60-600W, and the microwave is 25-60min / ultrasound is 5-20min in a cycle.

4. The method for preparing highly active selenized Tremella fuciformis polysaccharide according to claim 2, wherein: In the above steps, the mass ratio of the refined polysaccharide to sodium selenite is 1:0.4 to 1:2.4, and the mass ratio of sodium selenite to barium chloride is 1:0.8 to 1:2.

8.

5. The method for preparing highly active selenized Tremella fuciformis polysaccharide according to claim 2, wherein: The pH of the reaction solution was adjusted using 1-1.2 mol / L sodium bicarbonate.

6. Use of selenized Tremella fuciformis polysaccharide obtained by the preparation method according to claim 1 or 2 in the preparation of hypoglycemic drugs.

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