Preparation method and application of soybean peptide

Abstract

The invention provides a preparation method and application of a soybean peptide, in addition, a soybean antihypertensive active peptide SY-J-5 with a better antihypertensive characteristic is separated from soybeans, and the polypeptide has a higher ACE (angiotensin converting enzyme) inhibition rate; meanwhile, after the antihypertensive peptide SY-J-5 is applied to hypertensive rats, the effects of effectively reducing blood pressure and reducing ACE activity can be achieved, and the market application prospect is wide.

Description

Technical Field

[0001] The present application relates to the biological field, and specifically to a preparation method and application of a soybean peptide, wherein the soybean peptide can effectively lower blood pressure. Background Art

[0002] Currently, there are more than 200 traditional synthetic antihypertensive drugs, all of which require lifelong use and have significant side effects. Therefore, screening antihypertensive efficacy components from natural products has become one of the research hotspots in the development of new drugs and functional foods.

[0003] Bioactive peptides refer to a class of peptide compounds that are beneficial to the vital activities of biological organisms or have physiological effects. They are also called functional peptides or antihypertensive peptides. Antihypertensive peptides are a class of angiotensin-converting enzyme (ACE) inhibitors that lower blood pressure by inhibiting ACE activity. ACE is a metallopeptidase that contains two Zn2+ binding sites. The Zn2+ binding site is where the active group in the ACE catalytic reaction resides. The common action of various ACE inhibitors, including antihypertensive peptides, is to bind to the Zn2+ in the ACE active site, inactivating it. Antihypertensive peptides are competitive inhibitors with strong affinity for the ACE active site. Their affinity for ACE is stronger than that of Ang1 or bradykinin, and they are less likely to release from the ACE binding site. This hinders the biochemical reactions catalyzed by ACE: the hydrolysis of Ang1 to AngII and the hydrolysis of bradykinin to its inactive fragment, thereby lowering blood pressure. The inhibitory activity of antihypertensive peptides against ACE is primarily determined by two factors: the molecular weight of the peptide and its amino acid composition and structure. Research results also indicate that the molecular mass of the active portion is generally below 1000 u. The relationship between the amino acid composition of a peptide and its antihypertensive activity remains uncertain. However, a comprehensive analysis of the structures of known ACE inhibitory peptides derived from the hydrolysis of natural proteins reveals that the N-terminus generally contains long or branched hydrophobic amino acids (such as Leu, Ile, and Val), while the C-terminus generally contains cyclic aromatic amino acids (such as Phe, Tyr, Trp) or Pro.

[0004] Recent research has revealed that plant proteins are a rich source of antihypertensive peptides. Peptides extracted from some food-derived proteins, including whey protein, soy protein, and fish protein, exhibit antihypertensive activity after enzymatic hydrolysis. Antihypertensive peptides have been isolated from a variety of plants, including corn, soybeans, rice bran, wheat germ, buckwheat bran, rapeseed, and mushrooms. Two industrial enzymes, Protease A and Orientase B, were used to hydrolyze soy protein to screen for highly active antihypertensive peptides, and sensory evaluation of the highly active hydrolysates was performed. The results showed that the products of Protease A hydrolysis for 4-10 hours and Orientase B hydrolysis for 6-10 hours were oligopeptides composed of 2-5 amino acids, exhibiting high ACE inhibitory activity and minimal or no bitterness. These oligopeptides, due to their natural nature, safety, and mild effects, hold promise as effective antihypertensive ingredients for inclusion in the human diet. A blood pressure-lowering peptide with the sequence Gln-Ser-Gly-Pro was isolated from the peptide fraction of Shaoxing rice wine using ultrafiltration, macroporous resin column chromatography, and reversed-phase chromatography. Zein contains a high proportion of hydrophobic amino acids such as Ile, Leu, Val, and Ala, as well as Pro, making it an excellent raw material for the preparation of antihypertensive peptides. Zein was hydrolyzed with thermolysin for 5 hours, and then large peptide fragments were removed using an ultrafiltration membrane with a molecular weight cutoff of 5000 u, yielding a mixture of oligopeptides with strong ACE inhibitory activity. Furthermore, Leu-Pro-Pro, obtained by enzymatic hydrolysis of γ-zein, is the best ACE inhibitory peptide discovered to date, with blood pressure-lowering efficacy comparable to that of captopril.

[0005] Soybeans are a source of edible food, and the active peptides isolated and prepared from them have very stable safety. Although soy protein contains a large amount of ACE peptides, these active peptides are hidden inside the protein, and it is necessary to select a suitable protease to release them in a targeted manner in order to exhibit ACE inhibitory activity. The choice of protease is a key factor, which determines the position and number of hydrolyzed peptide bonds. Different enzymes hydrolyze different parts of the long peptide chain of the protein due to the specificity of the active group, generating different enzymatic products. Therefore, the choice of protease determines the hydrolysis efficiency and ACE inhibitory activity of the soy peptide. There are not enough studies on soybean antihypertensive peptides in the prior art, especially on active peptides with high blood pressure reduction. Summary of the Invention

[0006] The present invention provides an innovative soybean antihypertensive active peptide, which is named SY-J-5 and has an amino acid sequence as shown in SEQ ID NO: 1.

[0007] More specifically, the present invention also provides a pharmaceutical composition with blood pressure lowering effect, characterized in that the pharmaceutical composition contains soybean antihypertensive active peptide SY-J-5, and the amino acid sequence of the active peptide is shown in SEQ ID NO: 1.

[0008] More specifically, the present invention also provides the use of soybean antihypertensive peptide SY-J-5 in preparing a pharmaceutical composition with blood pressure lowering effect, wherein the amino acid sequence of the soybean antihypertensive peptide SY-J-5 is shown in SEQ ID NO: 1.

[0009] More specifically, the pharmaceutical composition further contains a pharmaceutically acceptable carrier or excipient.

[0010] According to the present invention, the composition is preferably in unit dosage form such as tablets, pills, capsules, powders, granules, sterile solutions or suspensions, metered aerosols or liquid sprays, drops, ampoules, automatic injector devices or suppositories; for oral, parenteral, intranasal, sublingual or rectal administration, or for administration by inhalation or insufflation. The formulation of the composition of the present invention can be readily accomplished by methods known in the art.

[0011] The precise nature of the carrier or other ingredients can shape the mode or route of administration of the composition. These compositions can be delivered via a range of delivery routes, including, but not limited to: enteral delivery, including oral and colonic; parenteral delivery, including injection; transdermal delivery, including skin patches and ointments; mucosal delivery, including nasal and inhalation; or via implantation at a specific site, including prosthetics, which may be used for this purpose or primarily for other purposes but have this benefit. Pharmaceutical compositions for oral administration can be in tablet, capsule, powder, gel, or liquid form. Tablets may include a solid carrier such as gelatin or an adjuvant. Capsules may have specialized properties, such as an enteric coating. Liquid pharmaceutical compositions typically include a liquid carrier such as water, petroleum, animal or vegetable oils, mineral oil, or synthetic oil. These may include physiological saline, dextrose or other sugar solutions, or glycols such as ethylene glycol, propylene glycol, or polyethylene glycol. When the solid ligand-modified polyoxy-hydroxymetal ion material needs to be maintained in a solid form, for example, to control the delivery of the composition of the material, such as when a liquid formulation of the material is prepared, the selection of the formulation ingredients may be necessary.

[0012] Specifically, the "pharmaceutically acceptable excipients" mentioned include any excipients conventionally used in pharmaceutical compositions. Such excipients may generally include one or more surfactants, inorganic or organic salts, stabilizers, diluents, solubilizers, reducing agents, antioxidants, chelating agents, preservatives, and the like. Typical examples of surfactants include: nonionic surfactants (HLB 6-18), such as sorbitan fatty acid esters (e.g., sorbitan monocaprylate, sorbitan monolaurate, sorbitan monopalmitate), glycerol fatty acid esters (e.g., glycerol monocaprylate, glycerol monomyristate, glycerol monostearate), polyglycerol fatty acid esters (e.g., polyglycerol (deca) monostearate, polyglycerol (deca) distearate, polyglycerol (deca) monolinoleate), polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene Sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate), polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan tetrastearate, polyoxyethylene sorbitan tetraoleate), polyoxyethylene glycerol fatty acid esters (e.g., polyoxyethylene glyceryl monostearate), polyethylene glycol fatty acid esters (e.g., polyethylene glycol distearate), polyoxyethylene alkyl ethers (e.g., polyoxyethylene lauryl ether), polyoxyethylene polyoxypropylene alkyl ethers ( For example, polyoxyethylene polyoxypropylene glycol ether, polyoxyethylene polyoxypropylene propyl ether, polyoxyethylene polyoxypropylene cetyl ether), polyoxyethylene alkylphenyl ether (for example, polyoxyethylene nonylphenyl ether), polyoxyethylene hydrogenated castor oil (for example, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil), polyoxyethylene beeswax derivatives (for example, polyoxyethylene sorbitol beeswax), polyoxyethylene lanolin derivatives (for example, polyoxyethylene lanolin), and polyoxyethylene fatty acid amides (for example, polyoxyethylene stearamide); anionic surfactants such as C10-C18 alkyl sulfate salts (for example, deca-C18 alkyl sulfate salts); and natural surfactants such as lecithin, glycerophospholipids, sphingophospholipids (e.g., sphingomyelin), and sucrose esters of C12-C18 fatty acids.

[0013] The pharmaceutical composition of the present invention further comprises a stabilizer. Examples of stabilizers include creatinine, an amino acid selected from histidine, alanine, glutamic acid, glycine, leucine, phenylalanine, methionine, isoleucine, proline, aspartic acid, arginine, lysine, and threonine, a carbohydrate selected from sucrose, trehalose, sorbitol, xylitol, and mannose, a surfactant selected from polyethylene glycol (PEG; e.g., PEG3350 or PEG4000) or a polyoxyethylene sorbitan fatty acid ester (e.g., polysorbate 20 or polysorbate 80), or any combination thereof.

[0014] The pharmaceutical composition of the present invention may also contain a suitable sweetener. Suitable sweeteners include water-soluble natural sweeteners such as monosaccharides, disaccharides and polysaccharides, such as xylose, ribose, glucose, mannose, galactose, fructose, dextrose, sucrose, invert sugar, maltose, partially hydrolyzed starch, or corn syrup solids and sugar alcohols such as sorbitol, xylitol, mannitol, dihydrochalcone, glycyrrhizin and steviarebaudia-na (carhaciendoside); water-soluble artificial sweeteners such as soluble saccharin salts, i.e., saccharin sodium or calcium salts, cyclamate salts, the free acid form of saccharin, and the synthetic sweetener 3,4-dihydro-6-methyl-1,2,3-oxathiazin-4-one 2,2-dioxide, particularly its potassium (acesulfame-K), sodium and calcium salts; dipeptidyl sweeteners such as L-aspartyl-L-phenylalanine methyl ester; and mixtures thereof, the preferred sweetener being saccharin sodium.

[0015] The pharmaceutical composition of the present invention also contains a preservative. Specific examples of preservatives include octadecyldimethylbenzylammonium chloride, hexamethonium chloride, benzalkonium chloride (a mixture of alkylbenzyldimethylammonium chlorides in which the alkyl group is a long-chain compound), benzethonium chloride, aromatic alcohols such as phenol, butyl alcohol, and benzyl alcohol, alkylparabens such as methyl or propylparaben, catechol, resorcinol, cyclohexanol, 3-pentanol, and m-cresol.

[0016] Suitable buffer salts include, but are not limited to, buffer salts selected from phosphate, citrate, acetate, and tartrate. In certain embodiments, the surfactant system comprises an amount of buffer salt of about 1mM to about 100mM buffer salt. In other embodiments, the surfactant system comprises an amount of buffer salt of about 2mM to about 50mM buffer salt. In other embodiments, the surfactant system comprises an amount of buffer salt of about 3mM to about 25mM buffer salt. In other embodiments, the surfactant system comprises an amount of buffer salt of about 5mM to about 15mM buffer salt. Still in other embodiments, the surfactant system comprises about 10mM buffer salt. In certain embodiments, the pH of the buffer salt is adjusted to about pH 6.0 to about pH 8.0. In other embodiments, the pH of the buffer salt is adjusted to about pH 6.5 to about pH 7.5. In other embodiments, the pH of the buffer salt is adjusted to about pH 6.7 to about pH 7.3. In one embodiment, the buffer salt comprises phosphate buffered saline (PBS). In another embodiment, the buffer salt comprises phosphate buffered saline at a concentration of about 10mM. In another embodiment, the buffer salt comprises phosphate buffered saline at a concentration of about 10 mM and a pH of about 6.9.

[0017] The pharmaceutical compositions of the present invention can be administered orally, by injection (e.g., subcutaneously, intravenously, intraperitoneally, or intramuscularly), by inhalation, or topically (e.g., intraocularly, intranasally, rectally, on wounds, on the skin). The route of administration can be determined based on the physicochemical characteristics of the treatment, special considerations regarding the disease, or the desire to optimize efficacy or reduce side effects. Preferably, the compositions of the present invention are administered by subcutaneous injection. It is contemplated that treatment is not limited to clinical use. Therefore, subcutaneous injection using a needle-free device may also be preferred.

[0018] In one embodiment, the present invention provides methods and medicaments for preventing hypertension in a subject with prehypertension, the methods comprising administering to the subject an effective amount of a polypeptide, thereby preventing hypertension in a subject with prehypertension. In certain embodiments of this aspect, the subject is at risk for developing elevated blood pressure or hypertension, hypertension, or prehypertension. These subjects may include subjects with one or more of a variety of factors known to be associated with an increased risk of developing elevated blood pressure or hypertension or hypertension. These risk factors include, for example, a family history of hypertension, diabetes, obesity, certain races or ethnicities, a sedentary lifestyle, age, alcohol consumption, smoking, caffeine use, diet, sodium sensitivity and salt intake, kidney disease and renal insufficiency, sleep apnea, pregnancy, cirrhosis of the liver, Cushing's disease, certain medications, emotional factors, stress, and the like. In one embodiment, the subject at risk for hypertension or hypertension has a disorder selected from the group consisting of kidney disease and renal insufficiency. In various embodiments, the subject at risk for hypertension or hypertension is non-anemic. In some embodiments, the hypertension or hypertension is associated with kidney disease.

[0019] Beneficial effects

[0020] The present invention provides a preparation method and application of soybean peptides. In addition, the present invention isolates a soybean antihypertensive active peptide SY-J-5 with good blood pressure-lowering properties from soybeans. The peptide has a strong ACE inhibition rate. At the same time, after the antihypertensive peptide SY-J-5 is administered to hypertensive rats, it can effectively lower blood pressure and reduce ACE activity, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Determination of the inhibitory effect of antihypertensive peptide SY-J-5 on ACE

[0022] Figure 2 Effects of antihypertensive peptide SY-J-5 on blood pressure in rats DETAILED DESCRIPTION

[0023] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0024] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter described in this disclosure belongs.

[0025] Example 1 Preliminary preparation of soybean antihypertensive active peptide

[0026] Soybeans were dried, crushed, and passed through an 80-mesh sieve. A 1:1 volume ratio of 0.1M NaOH and 95% ethanol was added to the mixture at a solid-liquid ratio of 1:15 (w / v). The mixture was mixed with high-speed stirring (1000 r / min) and then ground using a colloid mill to obtain a soy protein slurry. The soy protein slurry was heated to 88°C for 1.3 hours, then cooled to 55°C for enzymatic hydrolysis. The optimized enzymatic hydrolysis conditions were: enzyme dosage 3000 U / g, pH 7.0, hydrolysis temperature 55°C, solid-liquid ratio 1:9 (w / v), and enzymatic hydrolysis time 3 hours. During the enzymatic hydrolysis process, three ultrasound-assisted enzymatic hydrolysis cycles were performed, with each cycle lasting 1 hour, and ultrasonic treatment was performed at a power of 25W for 15 minutes. After the hydrolysis is completed, the hydrolyzate is placed in a boiling water bath for 10 minutes to inactivate the enzyme and terminate the reaction. The hydrolyzate is then quickly cooled to room temperature and centrifuged at 4000 r / min for 10 minutes to obtain the supernatant. The supernatant is then ultrafiltered using ultrafiltration membranes with a molecular weight cutoff of 3000 Da and 1000 Da to preliminarily obtain component group A with a molecular weight greater than 3000 Da, component group B with a molecular weight less than 3000 Da and greater than 1000 Da, and component group C with a molecular weight less than 1000 Da. The above three products were respectively measured for their in vitro ACE inhibition rates.

[0027] The ACE inhibition rate was determined using the following method:

[0028] The ACE inhibitory activity of each peptide solution was determined by adding 100 μL of 6.5 mmol / L HHL (Sigma) solution, 200 μL of each peptide solution, and 200 μL of 100 mmol / L pH 8.3 phosphate buffer to a test tube. The mixture was preheated in a 37°C water bath for 5 minutes. Then, 500 μL of ACE enzyme solution was added to initiate the reaction. After incubation at 37°C for 30 minutes, 100 μL of 1 mol / L HCl was added to terminate the reaction. 1.5 mL of ethyl acetate was then added, mixed thoroughly, and centrifuged (4000 rpm for 10 minutes). 1 mL of the upper ethyl acetate layer was transferred to another test tube and placed in a 120°C oven to evaporate the solvent for 30 minutes. After cooling, 6 mL of distilled water was added, and the absorbance was measured at 228 nm after vortex mixing. The calculation formula is as follows:

[0029] ACE inhibition rate (%) = (Ab-Aa) / (Ab-Ac) × 100%,

[0030] Note: Aa: Absorbance value of sample a. Sample a was added with an inhibitor during the reaction and is a sample for the reaction of ACE with HHL with the addition of an inhibitor. Ab: Absorbance value of sample b. Sample b was not added with an inhibitor during the reaction and, after completion of the reaction, an inhibitor was added to maintain equilibrium in the reaction system. This is a control for the complete reaction of ACE with HHL. Ac: Absorbance value of sample c. Sample c was inactivated prior to the reaction (by adding HCl beforehand) and then the inhibitor was added. This is a blank sample for the reaction of ACE with HHL. The results are shown in Table 1.

[0031] Table 1 ACE inhibition rate results of each group

[0032] Group ACE inhibition rate (%) Group A 51.74±2.14 Group B 63.43±3.07 Group C 89.31±4.56 Unfiltered supernatant after enzymatic hydrolysis 69.53±2.45

[0033] As shown in Table 1, after ultrafiltration of the soy peptide hydrolysate, the ACE inhibition rate of Fraction C was significantly improved compared to the unfiltered hydrolysate, while the ACE inhibition rates of Fractions A and B were lower than those of the unfiltered hydrolysate. This indicates that the antihypertensive active peptide components are primarily concentrated in the small peptide fraction. The ultrafiltration fractions with a molecular weight less than 1000 Da were collected, freeze-dried, and then further isolated and purified.

[0034] Example 2 Further separation and purification of the 1000Da component

[0035] The hydrolyzate's component C was separated by an ion exchange column using an anion exchange resin 201×7. The treated anion exchange resin was equilibrated with distilled water and then loaded onto a 20 mm × 200 mm column. A 0.2 g sample of the ultrafiltrate was loaded and eluted with pure water and 0.5 mol / L NaCl solution, respectively, at a flow rate of 1 drop / 3 seconds. The eluates were collected in separate tubes, each containing 1 mL. The anti-ACE activity of the eluates was assayed. The results showed that the anti-ACE activity of the pure water and saline eluates was 25.9% and 76.4%, respectively, indicating that the antihypertensive peptide was primarily concentrated in the saline eluate.

[0036] The ion exchange separation product was separated using a dextran gel column. After equilibration with distilled water, Sephadex G-15 was loaded onto a column (12 mm × 450 mm). 0.15 g of ion exchange salt eluent was selected for loading. The eluent was pure water at a flow rate of 1 drop / 5 s. The samples were collected in separate tubes, 1.5 mL per tube, and 55 tubes were collected. The activity of each peak was measured at 280 nm. It was found that tubes 15 and 16 had the highest inhibition rate on ACE. High-performance liquid chromatography was performed on tubes 15 and 16 at the same time, and it was found that both tubes had the same sharp absorption peak. The two tubes were subjected to mass spectrometry and sequence determination, and compared with the NCBI protein database to determine the amino acid sequence of the peptide as shown in SEQ ID NO: 1. The polypeptide was named SY-J-5 and was artificially synthesized for later use.

[0037] Example 3: Efficacy Verification of Antihypertensive Peptide SY-J-5

[0038] The antihypertensive peptide SY-J-5 peptide solution was taken and its ACE inhibitory activity was determined. 100 μL of 6.5 mmol / L HHL (Sigma) solution, 200 μL of each group of antihypertensive peptide SY-J-5 solution (their concentrations were 0 (blank control), 50 (group A), 100 (group B), 200 (group C), and 500 (group D) μg / mL, and the positive control was 100 μg / mL captopril) and 200 μL of 100 mmol / L pH 8.3 phosphate buffer were added to the test tubes in sequence. The mixture was preheated in a constant temperature water bath at 37°C for 5 min, and then 500 μL of ACE enzyme solution was added to start the reaction. After incubation in a 37°C water bath for 30 min, 100 μL of 1 mol / L HCl was added to terminate the reaction. Then add 1.5 mL of ethyl acetate, mix well, and centrifuge (4000 rpm, 10 min). Transfer 1 mL of the upper ethyl acetate layer to another test tube, place it in a 120°C oven to evaporate the solvent for 30 min, take it out and cool it, add 6 mL of distilled water, vortex mix, and measure the absorbance at 228 nm. The calculation formula is as follows:

[0039] ACE inhibition rate (%) = (Ab-Aa) / (Ab-Ac) × 100%,

[0040] Note: Aa: absorbance value of sample a. Sample a was added with inhibitor during the reaction. It is the sample of ACE and HHL reaction with inhibitor. Ab: absorbance value of sample b. Sample b was not added with inhibitor during the reaction. After the reaction, inhibitor was added to maintain the balance of the whole reaction system. It is the control of complete reaction of ACE and HHL. Ac: absorbance value of sample c. Sample c was inactivated before the reaction (HCl was added in advance) and then the inhibitor was added. It is the blank sample of ACE and HHL reaction. The results are shown in Figure 2. Figure 1 shown.

[0041] from Figure 1 The results show that under the same concentration conditions, the antihypertensive peptide SY-J-5 has an ACE inhibitory effect similar to that of the positive control group. When the concentration of the antihypertensive peptide SY-J-5 is 500 μg / mL, the ACE inhibition rate reaches (98.03±1.13)%, and the inhibitory effect is significant.

[0042] Example 4 Effect of Antihypertensive Peptide SY-J-5 on Blood Pressure in Rats

[0043] Forty SPF-grade essential hypertensive rats (SHR), male, 8-9 weeks old; and ten control SD rats, male, 8-9 weeks old, were purchased from Beijing Weitonglihua Experimental Animal Technology Co., Ltd.

[0044] SHR rats were allowed free access to food and drinking water and were disinfected regularly. They were pre-fed for one week and maintained at an ambient temperature of 25±1°C and a relative humidity of (55±5)%. After the SHR rats adapted to the environment, rats with similar body weight and blood pressure were selected for the experiment. The rats were randomly divided into 4 groups: 10 rats in each group. The 4 groups of SHR rats corresponded to the positive control group, blank control group, low-dose group and high-dose group, and were respectively given: captopril, distilled water, low-dose and high-dose antihypertensive peptide SY-J-5. The antihypertensive peptide SY-J-5 was gavaged into SHR rats in two dose groups: low dose (10 mg / kg·bw) and high dose (20 mg / kg·bw). The positive control group was gavaged with 10 mg / kg·bw captopril, and the blank control group was given distilled water of the corresponding dose. Each group was gavaged for 30 consecutive days. On the 30th day, the blood pressure of the rats was measured 2 hours after gavage. The results are as shown in the figure below. Figure 2 shown.

[0045] from Figure 2 As can be seen, the positive control group, low-dose group, and high-dose group showed a significant decrease in systolic blood pressure 2 hours after 30 days of continuous treatment compared to the blank control group (P < 0.05). Under treatment with the high-dose group, the blood pressure of SHR rats dropped to (115.2 ± 1.5) mmHg. This shows that the antihypertensive peptide SY-J-5 of the present invention has a good blood pressure-lowering effect.

[0046] After 30 days of long-term continuous oral administration to rats, each group of animals was deprived of food and water for 1 day and then sacrificed. Serum and lung tissue were collected and ACE activity in serum was measured using an ELISA kit. The results are shown in Table 2 below.

[0047] Table 2 Detection results of ACE activity in serum of rats in each group

[0048] Group Serum ACE activity (U / L) Positive control group 88.76±0.14# Blank control group 108.51±1.16 Low-dose group 92.56±0.25# High-dose group 85.98±0.31#

[0049] As can be seen from the results in Table 2, the positive control group, low-dose group, and high-dose group were able to inhibit the activity of the relevant ACE, with significant differences compared to the blank control group (p < 0.05). The antihypertensive peptide SY-J-5 of the present invention has a certain dose-dependent effect of inhibiting the activity of ACE. This shows that the antihypertensive peptide SY-J-5 of the present invention has the effect of lowering blood pressure by inhibiting the activity of ACE.

[0050] In addition, testing of the organs of rats in each group revealed no obvious toxic or side effects.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A soybean antihypertensive active peptide SY-J-5, characterized in that The amino acid sequence is shown in SEQ ID NO:

1.

2. A blood pressure lowering drug, characterized in that: Contains the soybean antihypertensive active peptide SY-J-5 as claimed in claim 1.

3. Use of the soybean antihypertensive active peptide SY-J-5 according to claim 1 in preparing a pharmaceutical composition for treating hypertension.

4. The use according to claim 3, wherein the pharmaceutical composition contains a pharmaceutically acceptable carrier.

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