Immunoregulatory activity heptapeptide as well as preparation method and application thereof
By extracting and purifying immunomodulatory active heptapeptides from rice bran, the technical challenge of high-value utilization of rice bran has been solved, achieving high-yield and high-purity preparation of active peptides for application in immunomodulatory drugs, food, or health products, thereby enhancing the economic value of rice bran.
Patent Information
- Application Number
- CN202510870730.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2025-10-17
AI Technical Summary
In the existing technology, there are few high-activity rice bran active peptide products, and there is a lack of effective preparation technology and structure identification, which limits the high-value utilization of rice bran.
Immunomodulatory active heptapeptide was extracted and purified from rice bran. The specific steps included pH adjustment, enzymatic hydrolysis, centrifugation, membrane separation, and reversed-phase chromatography purification to obtain an immunomodulatory active heptapeptide with the amino acid sequence Ala-Glu-Glu-Lys-Val-Arg-Gln.
The high-yield and high-purity preparation of immunomodulatory active heptapeptides is achieved, the added value of rice bran is improved, the heptapeptide has significant immunomodulatory activity, and can be used in immunomodulatory drugs, foods or health products.
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Figure CN120795075A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of medicine, and particularly relates to an immunoregulatory active heptapeptide and a preparation method and application thereof. BACKGROUND
[0002] Active peptides are important food functional factors, have biological activities such as immunoregulation, antioxidant, prevention of osteoporosis, and are widely used in food production such as health food and are popular with consumers. Active peptides are important food functional factors, have biological activities such as immunoregulation, antioxidant, prevention of osteoporosis, and are widely used in food production such as health food and are popular with consumers. Rice bran is a complex composed of pericarp, seed coat, aleurone layer and embryo in the process of rice milling, and is rich in protein (12%-15%), fat (16%-20%), dietary fiber (14%) and bioactive substances such as γ-oryzanol, tocopherol and phytic acid. Rice bran protein active peptides exhibit significant physiological regulation functions due to their unique amino acid sequences and spatial conformation. Existing studies have confirmed that rice bran protein active peptides mainly have biological activity characteristics such as antioxidant, antihypertensive, immunoregulation, low allergenicity and the like. At present, although there are many reports on rice bran active peptides, active peptide products with high activity are still few. Therefore, it is necessary to carry out researches on preparation process, structure identification and activity evaluation of rice bran active peptides, and to reveal the chemical structure of main active peptides, which has important significance for high-value utilization of rice bran. SUMMARY
[0003] The first object of the present application is to provide an immunoregulatory active heptapeptide separated from rice bran protein.
[0004] The immunoregulatory active heptapeptide of the present application has an amino acid sequence of Ala-Glu-Glu-Lys-Val-Arg-Gln.
[0005] The second object of the present application is to provide application of the above-mentioned immunoregulatory active heptapeptide in preparation of immunoregulatory active drugs, foods or health products.
[0006] Preferably, the drug contains pharmaceutically acceptable excipients.
[0007] Preferably, the drug can be prepared into various dosage forms available, such as powders, injections, suspensions and the like.
[0008] The third object of the present application is to provide an immunoregulatory active drug, food or health product containing the immunoregulatory active heptapeptide of claim 1 as an active ingredient.
[0009] The fourth object of the present application is to provide a method for preparing the above-mentioned immunoregulatory active heptapeptide, characterized by comprising the following steps:
[0010] The rice bran is dissolved in water, the pH value is adjusted to 8, the protein is fully dissolved by stirring extraction, first, the insoluble residues are removed by coarse filtration with gauze, then the supernatant is collected by centrifugation, the pH is adjusted to 4.5 to precipitate the protein, the precipitate is collected by centrifugation, and the rice bran protein is obtained by freeze-drying. The rice bran protein is dispersed in water, hydrolyzed by adding protease, and then the enzyme is inactivated by high temperature. The supernatant of the protein hydrolysate is obtained by centrifugation. The rice bran protein hydrolysate is dried after membrane separation. The rice bran protein hydrolysate is purified by a C18 reverse-phase chromatography column. Water-ethanol is used as an eluent. The target active peptide component eluted at an ethanol volume fraction of 10% is collected. The target active peptide component eluted at an ethanol volume fraction of 10% is purified by a Sephadex LH-20 chromatography column. The target immunomodulatory active heptapeptide is obtained by drying after concentration.
[0011] Preferably, distilled water is added at a material-liquid ratio of 1:10, 1M NaOH solution is used to adjust the pH to 8.0, and the protein is fully dissolved by stirring extraction for 2 hours. First, the insoluble residues are removed by coarse filtration with gauze. Then, the supernatant is collected by centrifugation at 3000 r / min for 20 minutes. The pH of the supernatant is adjusted to 4.5 with 1M HCl to precipitate the protein. The precipitate is collected by centrifugation at 3000 r / min for 20 minutes. The rice bran protein is obtained by freeze-drying. The rice bran protein is dispersed in water, hydrolyzed by adding protease, and then the enzyme is inactivated by high temperature. The supernatant of the protein hydrolysate is obtained by centrifugation. The rice bran protein hydrolysate is dried after membrane separation. The rice bran protein hydrolysate is purified by a C18 reverse-phase chromatography column. Water-ethanol is used as an eluent. The target active peptide component eluted at an ethanol volume fraction of 10% is collected. The target active peptide component eluted at an ethanol volume fraction of 10% is purified by a Sephadex LH-20 chromatography column. The target immunomodulatory active heptapeptide is obtained by drying after concentration.
[0012] Preferably, the "hydrolysis by adding protease, inactivation of the enzyme by high temperature, centrifugation to obtain the supernatant of the protein hydrolysate, and drying after membrane separation to obtain the rice bran protein hydrolysate" is as follows: 0.2%-2% alkaline protease is added to the rice bran protein at pH 7.0-10.0 and a temperature of 35-65°C for 1-5 hours. Then, 0.2%-2% alkaline protease is added at pH 7.0-10.0 and a temperature of 35-65°C for 1-5 hours. Then, 0.2%-2% neutral protease is added at pH 7.0-9.0 and a temperature of 45-65°C for 1-5 hours. The enzyme is inactivated by heating to 90°C for 20 minutes. The supernatant of the protein hydrolysate is obtained by centrifugation. The filtrate is collected by filtering with an ultrafiltration membrane with a molecular weight cutoff of 3000 daltons. The rice bran protein hydrolysate is obtained by spray drying.
[0013] Preferably, after the protein is hydrolyzed by the protease, the enzyme is inactivated by high temperature, the supernatant of the protein hydrolysate is obtained by centrifugation, and the rice bran protein hydrolysate is obtained by drying after membrane separation. The rice bran protein isolate is added with 0.5% alkaline protease, the pH is 9.5, the temperature is 65°C, and the enzyme hydrolysis is performed for 3 hours. Then, 0.5% neutral protease is added, the pH is 8.0, the temperature is 60°C, and the enzyme hydrolysis is performed for 3 hours. The temperature is increased to 90°C to inactivate the enzyme, and the supernatant of the protein hydrolysate is obtained by centrifugation at 5000g for 10 minutes. The active carbon is used for decolorization, the ultrafiltration membrane with a molecular weight cut-off of 3000 daltons is used for filtration, the permeate is collected, and the rice bran protein hydrolysate is obtained by spray drying.
[0014] A fifth object of the present application is to provide the use of rice bran in the preparation of the immunomodulatory active heptapeptide.
[0015] The present application provides an immunomodulatory active heptapeptide prepared from rice bran, which has a yield of 20-78 g / kg (purity of 75-95%) and good immunomodulatory activity, and can be used in the preparation of immunomodulatory active drugs, food or health products. The present application provides a new method for the preparation of immunomodulatory active heptapeptide, which is of great significance for the deep processing and utilization of rice bran, the improvement of the added value of rice bran, and the sustainable development of the industry. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 is the secondary mass spectrum of the immunoregulatory peptide;
[0017] Figure 2 is the amount of NO produced by macrophages induced by the immunoregulatory peptide, wherein the abscissa represents the concentration of the immunoregulatory peptide. DETAILED DESCRIPTION
[0018] The following examples are further illustrations of the present application and are not limitations of the present application.
[0019] Example 1: Preparation, isolation and structural identification of the immunomodulatory active heptapeptide
[0020] I. Preparation and isolation of the immunoregulatory peptide
[0021] 1) Selection of materials: red rice bran is selected
[0022] 2) Preparation: add 10 times the mass of water to the rice bran, and then stir and disperse.
[0023] 3) Preparation of rice bran protein: adjust the pH of the mixture to 8.0 with 1M NaOH solution, extract for 2h under stirring, first remove the insoluble residue with gauze, then centrifuge at 3000r / min for 20 minutes to remove the insoluble precipitate. Collect the supernatant, adjust the pH to 4.5 with 1M hydrochloric acid, centrifuge at 3000r / min for 20 minutes to collect the precipitate, freeze-dry to obtain rice bran protein.
[0024] 4) Extraction: 50 g of rice bran protein was added to 500 mL of water, then dispersed by stirring to obtain rice bran protein isolate.
[0025] 5) Enzymatic hydrolysis: 0.5% of alkaline protease (Novozyme) was added according to the mass of the rice bran protein isolate, pH 9.5, temperature 65°C, and enzymatic hydrolysis was performed for 3 hours, then 0.5% of neutral protease (Novozyme) was added, pH 8.0, temperature 60°C, and enzymatic hydrolysis was performed for 3 hours. The temperature was raised to 90°C for 20 minutes to inactivate the enzymes, and centrifugation (5000 g, 10 min) was performed to obtain the supernatant of the protein hydrolysate, which was decolorized with activated carbon (10%, w / v g / ml) for 24 hours. Ultrafiltration was performed using a membrane with a molecular weight cutoff of 3000 daltons, and the permeate was collected and spray dried to obtain the rice bran protein hydrolysate.
[0026] 6) Column purification: the rice bran protein hydrolysate was purified using a C18 reverse-phase chromatography column (15 x 460 mm) and eluted with a gradient of water and ethanol, specifically, the ethanol volume fraction was gradually increased from 0% to 20% at an interval of 2%, and the target active peptide component eluted at an ethanol volume fraction of 10% was collected, concentrated, and then purified using a Sephadex LH-20 chromatography column (15 x 460 mm) and eluted with a 10% ethanol aqueous solution, and the target active peptide component eluted at an ethanol volume fraction of 10% was collected, concentrated, and then dried to obtain the target immunomodulatory active heptapeptide.
[0027] The yield of the immunomodulatory active heptapeptide obtained by this method was 43-60 g / kg, and the purity was 90%.
[0028] II. Structure identification of the immunomodulatory active heptapeptide
[0029] The immunomodulatory active heptapeptide was soluble in water, and the immunomodulatory active heptapeptide was analyzed by high-resolution liquid chromatography-mass spectrometry, and the results are shown in Figure 1 According to the secondary mass spectrometry information, the amino acid sequence of the immunomodulatory active heptapeptide was identified as: Ala-Glu-Glu-Lys-Val-Arg-Gln.
[0030] The molecular ion peak of the immunomodulatory active heptapeptide in the cation mode was m / z 421.47, z = 2.
[0031] m / z 659.38, 537.29, 402.25, 300 are y ion signals of the fragments Glu-Glu-Lys-Val-Arg-Gln, Lys-Val-Arg-Gln, Val-Arg-Gln, Arg-Gln respectively. m / z 713.39, 642.77, 453.22, 382.5 are b ion signals of the fragments Ala-Glu-Glu-Lys-Val-Arg, Ala-Glu-Glu-Lys-Val, Ala-Glu-Glu-Lys, Ala-Glu-Glu respectively.
[0032] The presence of these signals confirms that the structure of the immunomodulatory active heptapeptide is Ala-Glu-Glu-Lys-Val-Arg-Gln. After the heptapeptide is artificially synthesized, it is detected by liquid chromatography-mass spectrometry, and it is found that the retention time is consistent with that of the identified substance, and the mass spectrum fragments are consistent. Therefore, the structure is determined to be the above structure.
[0033] III. Activity determination of the immunomodulatory active heptapeptide
[0034] Logarithmic growth phase RAW264.7 cells were inoculated in a 96-well plate and placed in a 37°C carbon dioxide incubator for 24 hours. After the culture medium was discarded, DMEM medium containing different concentrations of polypeptides was added to the control wells, and DMEM medium without sample was added to the control wells. After being placed in the incubator for 24 hours, the culture medium was collected, and the amount of nitric oxide (NO) release was determined using a nitric oxide detection kit, with three replicates for each test. The concentration of NO in the culture medium was calculated according to the standard curve, and the cells without sample treatment were used as a blank control.
[0035] The experimental results are shown in Table 1. Figure 2 Figure 2 The results show that the immunomodulatory active heptapeptide has immunomodulatory activity, and the amount of NO produced by macrophages is used as an indicator. Compared with the blank control, the immunomodulatory active heptapeptide can significantly promote the production of NO at the lowest dosage (0.2 mg / mL), confirming that it has significant immunomodulatory activity. Within the dosage range of 0.2-1.5 mg / mL, the immunomodulatory activity of the immunomodulatory active heptapeptide shows a clear dose-effect relationship. At a dosage of 1.5 mg / mL, the concentration of NO is as high as 4.1 μM.
[0036] Example 2:
[0037] I. Preparation and separation of immunologically active peptides
[0038] 1) Selection of materials: red rice bran is selected
[0039] 2) Preparation: Add 5 times the mass of water to the rice bran, then stir and disperse.
[0040] 3) Rice bran protein preparation: adjust the pH of the mixture to 8.5 with 1M NaOH solution, extract under stirring for 1 h, first remove the insoluble residue with gauze, then remove the insoluble precipitate by centrifugation at 3000 r / min for 20 min. Collect the supernatant, adjust the pH to 5.0 with 1M hydrochloric acid, centrifuge at 3000 r / min for 20 min to collect the precipitate, freeze-dry to obtain rice bran protein.
[0041] 4) Extraction: add 50 g of rice bran protein to 500 mL of water, then stir and disperse to obtain rice bran protein isolate.
[0042] 5) Enzymatic hydrolysis: add 0.75% of alkaline protease (Novozymes) according to the mass of rice bran protein isolate, pH 8.5, temperature 50°C, hydrolyze for 3 hours, then add 0.35% of neutral protease (Novozymes), pH 7.0, temperature 50°C, hydrolyze for 2 hours. Heat to 90°C for 20 min to inactivate the enzyme, centrifuge (5000g, 10 min) to obtain the supernatant of the protein hydrolysate, decolorize with activated carbon (10%, w / v g / ml) for 24 hours. Filter with an ultrafiltration membrane with a molecular weight cutoff of 3000 daltons, collect the permeate and spray dry to obtain rice bran protein hydrolysate.
[0043] 6) Column purification: purify the rice bran protein hydrolysate with a C18 reverse phase chromatography column (15 x 460 mm) using water and ethanol aqueous solution gradient elution, specifically gradually increasing the ethanol volume fraction from 0% to 20% at an amplitude of 2%, collect the target active peptide component eluted at an ethanol volume fraction of 6%, concentrate and purify with a Sephadex LH-20 chromatography column (15 x 460 mm) using ethanol aqueous solution elution at a volume fraction of 6%, collect the target active peptide component eluted at an ethanol volume fraction of 6%, concentrate and dry to obtain the target immunomodulatory active heptapeptide.
[0044] The yield of the immunomodulatory active heptapeptide obtained by this method is 60-78 g / kg, and the purity is 80-95%.
[0045] Example 3:
[0046] I. Preparation and separation of immunologically active peptides
[0047] 1) Selection of materials: select red rice bran
[0048] 2) Preparation: add water in an amount of 15 times the mass of the rice bran, then stir and disperse.
[0049] 3) Rice bran protein preparation: adjust the pH of the mixed solution to 9.0 with 1M NaOH solution, extract for 3h under stirring, first remove the insoluble residue with gauze, then remove the insoluble precipitate by centrifugation at 3000r / min for 20 minutes. Collect the supernatant, adjust the pH to 5.5 with 1M hydrochloric acid, centrifuge at 3000r / min for 20 minutes to collect the precipitate, freeze-dry to obtain rice bran protein.
[0050] 4) Extraction: add 50g of rice bran protein to 750mL of water, then stir and disperse to obtain rice bran protein isolate.
[0051] 5) Enzymatic hydrolysis: add 1% of alkaline protease (Novozymes) according to the mass of rice bran protein isolate, pH 8.5, temperature 50°C, hydrolyze for 5 hours, then add 1% of neutral protease (Novozymes), pH 7.0, temperature 50°C, hydrolyze for 5 hours. Heat to 90°C for 20 minutes to inactivate the enzyme, centrifuge (5000g, 10min) to obtain the supernatant of the protein hydrolysate, decolorize with activated carbon (10%, w / v g / ml) for 24h. Filter with an ultrafiltration membrane with a molecular weight cutoff of 3000 daltons, collect the permeate and spray dry to obtain rice bran protein hydrolysate.
[0052] 6) Column purification: purify the rice bran protein hydrolysate with a C18 reverse phase chromatography column (15x460mm), elute with water and ethanol aqueous solution gradient, specifically gradually increase the ethanol volume fraction from 0% to 20% at an amplitude of 2%, collect the target active peptide component eluted at an ethanol volume fraction of 6%, concentrate, then purify with a Sephadex LH-20 chromatography column (15x460mm), elute with an ethanol aqueous solution with a volume fraction of 6%, collect the target active peptide component eluted at an ethanol volume fraction of 6%, concentrate and dry to obtain the target immunomodulatory active heptapeptide.
[0053] The yield of the immunomodulatory active heptapeptide obtained by this method is 20-58g / kg, and the purity is 80-95%.
[0054] Example 4:
[0055] I. Preparation and separation of immunologically active peptides
[0056] 1) Selection of materials: select red rice bran
[0057] 2) Preparation: add 10 times the mass of water to the rice bran, then stir and disperse.
[0058] 3) Rice bran protein preparation: The pH of the mixture was adjusted to 8.0 with 1 M NaOH solution, and extraction was performed under stirring for 2 h. The insoluble residue was removed by coarse filtration with gauze, and the insoluble precipitate was removed by centrifugation at 3000 r / min for 20 min. The supernatant was collected, and the pH was adjusted to 4.5 with 1 M hydrochloric acid. The precipitate was collected by centrifugation at 3000 r / min for 20 min, freeze-dried, and rice bran protein was obtained.
[0059] 4) Extraction: 50 g of rice bran protein was added to 1000 mL of water, and then dispersed by stirring to obtain rice bran protein isolate.
[0060] 5) Enzymatic hydrolysis: 0.5% of alkaline protease (Novozymes) was added according to the mass of rice bran protein isolate, pH 9.5, temperature 60°C, and enzymatic hydrolysis was performed for 3 h. Then, 0.5% of neutral protease (Novozymes) was added, pH 8.0, temperature 60°C, and enzymatic hydrolysis was performed for 3 h. The temperature was raised to 90°C for 20 min to inactivate the enzyme, and the supernatant of the protein hydrolysate was obtained by centrifugation (5000 g, 10 min). Activated carbon (10%, w / v) was used for decolorization for 24 h. Ultrafiltration was performed using a membrane with a molecular weight cutoff of 3000 daltons, and the permeate was collected and spray-dried to obtain rice bran protein hydrolysate.
[0061] 6) Column purification: The rice bran protein hydrolysate was purified using a C18 reverse-phase chromatography column (15 x 460 mm) and eluted with water and ethanol aqueous solution gradient. Specifically, the ethanol volume fraction was gradually increased from 0% to 20% at an amplitude of 2%, and the target active peptide component eluted at an ethanol volume fraction of 6% was collected. After concentration, the Sephadex LH-20 chromatography column (15 x 460 mm) was used for purification, and the target active peptide component eluted at an ethanol volume fraction of 6% was collected. After concentration and drying, the target immunomodulatory active heptapeptide was obtained.
[0062] The yield of the immunomodulatory active heptapeptide obtained by this method was 30-48 g / kg, and the purity was 80-95%.
Claims
1. An immunomodulatory heptapeptide, characterized in that: The amino acid sequence is: Ala-Glu-Glu-Lys-Val-Arg-Gln.
2. Use of the immunomodulatory heptapeptide according to claim 1 in the preparation of immunomodulatory drugs, foods or health products.
3. The use according to claim 2, characterized in that The medicine contains pharmaceutically acceptable excipients.
4. The use according to claim 2, characterized in that The medicine can be prepared into various dosage forms, such as powder, injection, suspension, etc.
5. An immunomodulatory drug, food or health product, characterized in that: Contains the immunomodulatory active heptapeptide according to claim 1 as an active ingredient.
6. A method for preparing the immunomodulatory heptapeptide according to claim 1, characterized in that: The following steps are involved: Rice bran is dissolved in water, the pH value is adjusted to 8, and the protein is extracted by stirring to fully dissolve the protein. The protein is first coarsely filtered with gauze to remove insoluble residues, and then the supernatant is collected by centrifugation. The pH value is adjusted to 4.5 to precipitate the protein. The precipitate is collected by centrifugation and freeze-dried to obtain rice bran protein. The rice bran protein is dispersed in water, hydrolyzed with protease, and then the enzyme is inactivated by high temperature. The supernatant of the protein hydrolyzate is obtained by centrifugation, membrane separation and drying to obtain rice bran protein hydrolyzate. The rice bran protein hydrolyzate is purified by reverse chromatography column for active peptides, gradient elution with water and ethanol aqueous solution is performed, and the target active peptide component is collected. The target active peptide component is concentrated and purified by Sephadex LH-20 chromatography column. The target immunomodulatory active heptapeptide is concentrated and dried to obtain the target immunomodulatory active heptapeptide. Preferably, the rice bran protein is dispersed in water by adding the rice bran protein to 5-20 times its mass of water, and then stirred and dispersed.
7. The method according to claim 6, characterized in that Distilled water was added at a material-liquid ratio of 1:10, the pH was adjusted to 8.0 with 1M NaOH solution, and the mixture was stirred and extracted for 2 hours to fully dissolve the protein. The protein was first coarsely filtered with gauze to remove insoluble residues, and then centrifuged at 3000r / min for 20 minutes to collect the supernatant. The pH of the supernatant was adjusted to 4.5 with 1M HCl to precipitate the protein. The protein was centrifuged at 3000r / min for 20 minutes to collect the precipitate. The rice bran protein was freeze-dried to obtain rice bran protein. The rice bran protein was dispersed with water, hydrolyzed with protease, and the enzyme was inactivated by high temperature. The supernatant of the protein hydrolyzate was obtained by centrifugation, and dried after membrane separation to obtain rice bran protein hydrolyzate. The rice bran protein hydrolyzate was purified by C18 reverse phase chromatography column, using water-ethanol as eluent, and eluted with a gradient concentration of ethanol from 0% to 20% by gradually increasing the volume fraction of ethanol from 2.5% to 20%. The target active peptide component eluted with a volume fraction of 10% ethanol was collected, and the target active peptide component was concentrated and purified by ephadex The target active peptide components eluted with 10% ethanol were collected, concentrated and dried to obtain the target immunomodulatory active heptapeptide.
8. The method according to claim 6, characterized in that The method of "adding protease for hydrolysis, inactivating the enzyme at high temperature, centrifuging to obtain a supernatant of the protein hydrolysate, separating with a membrane and then drying to obtain the rice bran protein hydrolysate" comprises: adding 0.2%-2% alkaline protease according to the mass of the rice bran protein, setting the pH value to 7.0-10.0 and the temperature to 35-65°C, performing enzymatic hydrolysis for 1-5 hours, then adding 0.2%-2% alkaline protease, setting the pH value to 7.0-10.0 and the temperature to 35-65°C, performing enzymatic hydrolysis for 1-5 hours, then adding 0.2%-2% neutral protease, setting the pH value to 7.0-9.0 and the temperature to 45-65°C, performing enzymatic hydrolysis for 1-5 hours, heating to 90°C and maintaining for 20 minutes to inactivate the enzyme, centrifuging to obtain a supernatant of the protein hydrolysate, filtering with an ultrafiltration membrane with a molecular weight cut-off of 3000 Daltons, collecting the permeate and spray drying to obtain the rice bran protein hydrolysate.
9. The method according to claim 8, characterized in that After the enzyme is hydrolyzed by adding protease, the enzyme is inactivated by high temperature, and the supernatant of the protein hydrolyzate is obtained by centrifugation. The supernatant of the protein hydrolyzate is separated by membrane and then dried. The rice bran protein hydrolyzate is obtained by adding 0.5% alkaline protease according to the mass of the rice bran protein isolate, adjusting the pH to 9.5 and the temperature to 65°C, performing enzymolysis for 3 hours, then adding 0.5% neutral protease, adjusting the pH to 8.0 and the temperature to 60°C, performing enzymolysis for 3 hours, heating the mixture to 90°C and maintaining the temperature for 20 minutes to inactivate the enzyme, and centrifuging the mixture at 5000g for 10 minutes to obtain the supernatant of the protein hydrolyzate. The supernatant is decolorized by activated carbon, filtered by an ultrafiltration membrane with a molecular weight cutoff of 3000 Daltons, and the permeate is collected and spray-dried to obtain the rice bran protein hydrolyzate.
10. Use of rice bran in the preparation of the immunomodulatory heptapeptide according to claim 1.