LHLPLLVP polypeptide, goat milk powder with blood pressure lowering effect and method

Abstract

The invention provides an LHLPLLVP polypeptide, goat milk powder with an effect of reducing blood pressure and a method. The LHLPLLVP polypeptide with a function of inhibiting ACE (Angiotensin Converting Enzyme) activity is synthesized through reasonable design; in-vivo and in-vitro experiments prove that the LHLPLLVP polypeptide and goat milk are mixed and freeze-dried to prepare the functional goat milk powder, and the functional goat milk powder has the advantages of strong ACE inhibitory activity and antihypertensive effect, low production cost, no resource limitation, small environmental pollution, mass production, safety and wide application prospect in the food industry.

Description

Technical Field

[0001] The invention belongs to the technical field of dairy product processing, and in particular belongs to goat milk powder with blood pressure lowering effect and a preparation method thereof. Background Art

[0002] Hypertension, a common cardiovascular disease, poses a serious threat to human health. Its characteristic is that it is incurable, and patients need to rely on drugs for a long time or even for life to control the disease. In the human body, a physiological mechanism called the renin-angiotensin-aldosterone system (RAS) converts angiotensin I (Ang I) into angiotensin II (Ang II) through the action of angiotensin converting enzyme (ACE). This process causes strong contraction of blood vessels, which in turn significantly increases vascular pressure. In order to deal with this problem, the medical community has designed angiotensin converting enzyme inhibitors (ACEI) drugs. This type of drug effectively prevents the conversion of Ang I to Ang II by inhibiting ACE in the RAS system, thereby reducing the level of Ang II, allowing blood vessels to dilate and blood pressure to drop.

[0003] Goat milk, a dairy product known as the "king of milk", has nutrients very similar to human milk and can be called the best of milk. Compared with cow milk and human milk, goat milk has smaller casein particles and milk fat globules, which makes it easier to be absorbed by the human body. At the same time, goat milk is rich in short-chain and medium-chain unsaturated fatty acids, which are essential for human health. In addition, goat milk also contains a large amount of active immunoglobulins, which can significantly enhance the body's immunity. The active factor EGF in goat milk helps promote the growth of epithelial cells, while superoxide dismutase (SOD) has significant anti-inflammatory and anti-aging effects. It is worth mentioning that goat milk is also rich in DHA, which has a positive effect on the development of infants' intelligence and vision. In addition, the natural weak alkaline nature of goat milk gives it good buffering properties, which helps promote the recovery of diseases such as nephritis, tuberculosis and asthma. However, the nutritional ingredients of goat milk powder on the market are relatively single, and the efficacy is limited, which cannot meet the diversified nutritional needs of consumers. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a LHLPLLVP polypeptide and goat milk powder with blood pressure lowering effect and a method, a polypeptide with the function of inhibiting ACE activity is synthesized by reasonable design; and it is proved through in vivo and in vitro experiments that the polypeptide is mixed with goat milk and freeze-dried, and auxiliary materials such as sweeteners can be added to prepare functional goat milk powder, which has strong ACE inhibitory activity and blood pressure lowering effect, has low production cost, is not limited by resources, has little environmental pollution, can be mass-produced and the product is safe, and has broad application prospects in the food industry.

[0005] To achieve the above object, the present invention provides the following technical solution: a LHLPLLVP polypeptide having the function of inhibiting ACE activity.

[0006] The present invention also provides a composition, which comprises the above-mentioned LHLPLLVP polypeptide and a carrier acceptable in medicine, food or health care products.

[0007] The present invention also provides use of the LHLPLLVP polypeptide or the composition in preparing a product for treating and / or preventing hypertension.

[0008] The present invention also provides a food with blood pressure lowering effect, wherein LHLPLLVP polypeptide is added to the food, and the LHLPLLVP polypeptide has the function of inhibiting ACE activity.

[0009] The present invention also provides a goat milk powder with blood pressure lowering effect, which is obtained by adding LHLPLLVP polypeptide into goat milk and freeze-drying. The LHLPLLVP polypeptide has the function of inhibiting ACE activity.

[0010] Furthermore, the LHLPLLVP polypeptide is added in the form of a distilled water solution of the polypeptide, the concentration of the LHLPLLVP polypeptide aqueous solution is 0.1 mg / mL to 0.5 mg / mL, and the amount of the LHLPLLVP polypeptide aqueous solution added is 0.01 mg / mL to 0.05 mg / mL based on the volume of goat milk.

[0011] Furthermore, the purity of the LHLPLLVP polypeptide is greater than 95%.

[0012] Furthermore, the goat milk is skimmed goat milk.

[0013] Furthermore, the raw materials also include glucose and an antioxidant, the glucose is added in an amount of 1 g / L to 10 g / L, and the antioxidant is added in an amount of 0.01 g / g to 0.1 g / g.

[0014] The present invention also provides a method for preparing the above-mentioned goat milk powder with blood pressure lowering effect, and the specific steps are as follows: Adding the LHLPLLVP polypeptide aqueous solution into goat milk, stirring and standing, to obtain polypeptide-containing goat milk; The polypeptide-containing goat milk is vacuum freeze-dried to obtain goat milk powder with blood pressure lowering effect.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: The structure of the LHLPLLVP polypeptide provided by the present invention was identified by mass spectrometry (data see Figure 1), molecular docking technology was used to simulate that these polypeptides can bind to the ACE active site (data are shown in Table 4), and theoretically have strong ACE inhibitory activity. The LHLPLLVP polypeptide was verified in vitro using an in vitro test (using the HHL solution method, see Table 2), which proved that the LHLPLLVP polypeptide had the strongest in vitro ACE inhibitory activity (data are shown in Table 3). Animal experiments were then used for in vivo verification, and animal experiments proved that the LHLPLLVP polypeptide can significantly reduce the systolic and diastolic blood pressure of hypertensive mice (data are shown in Table 5). The LHLPLLVP polypeptide showed the best ACE inhibitory effect in both in vivo and in vitro verifications. The present invention focuses on the effect of the LHLPLLVP polypeptide in goat milk.

[0016] The goat milk powder with blood pressure lowering function prepared by mixing polypeptide with goat milk powder of the present invention fully utilizes goat milk resources and also gives goat milk powder a new blood pressure lowering effect. The LHLPLLVP polypeptide is added to goat milk in the form of a solution, and its ACE inhibitory activity is as high as 82.1%. After freeze-drying, it is prepared into goat milk powder. The ACE inhibitory activity of goat milk powder can reach 78.2% after testing. Testing of goat milk powder indicators proves that the addition of polypeptide does not affect the flavor and appearance quality of goat milk powder (Example 1), proving that the addition of LHLPLLVP polypeptide to goat milk can make goat milk have ACE inhibitory activity and give it a significant blood pressure lowering effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the mass spectrometry identification diagram of LHLPLLVP polypeptide. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0019] The present invention uses the ACE active site as a reference, screens the amino acid sites that can bind to ACE in the databases PepBank (http: / / pepbank.mgh.harvard.edu / ) and BIOPEP (http: / / www.uwm.edu.pl / biochemia / index.php / en / biopep), designs sequences with similar structures for chemical synthesis, and obtains polypeptides with the function of inhibiting ACE activity. The present invention designs a total of 12 polypeptides, as shown in Table 1.

[0020] Table 1 Amino acid sequences of synthetic peptides

[0021] 1. Taking the chemical synthesis of LHLPLLVP polypeptide as an example, the specific steps for preparing a polypeptide having the function of inhibiting ACE activity are as follows: Weigh 0.6g of dichlororesin (substitution degree is 0.3mmol / g) and put it into the reaction tube, soak it with 50mL of dichloromethane (DCM) for 30min, and wash it with dimethylformamide (DMF) three times. Add 150mg of the first amino acid Fmoc-Leu-OH, add 9mL of DCM (15mL / g) to dissolve it, and then add 0.2mL of N,N-diisopropylethylamine (DIEA) to react for 1.5-2h. Seal the head with methanol solution (methanol: DIEA: DCM=1:1:2) for 30min, then wash it with DMF four times, and drain it for use. Add an appropriate amount of 20% piperidine solution (piperidine / DMF=1:4), react for 20 min, wash it with DMF four times, and then drain it. Take a small amount of resin (about 20 resins) for ninhydrin detection. If the resin has color, the deprotection is successful.

[0022] Weigh 0.45mmol of the second amino acid Fmoc-His-OH and 0.45mmol of 1-hydroxybenzotriazole (HOBT), add a small amount of DMF (just enough to cover the resin) to dissolve it, then add 0.2 mL of 1,3-diisopropylcarbodiimide (DIC) to the reactor, react for 30 minutes, and detect by ninhydrin. Wash the resin four times with DMF and drain. Add a certain amount of 20% piperidine (piperidine / DMF=1:4) to the reactor, wash four times with DMF, then drain, and detect by ninhydrin. And so on, connect the remaining amino acids of the polypeptide in sequence. Weigh the resin after the reaction and add 10 times the volume of cutting solution, react for 1.5~2h (cutting solution: 95%TFA+2%EDT+2%Tis+1%H2O), filter out the resin, add 4~5 times the volume of ether and centrifuge, remove the supernatant, wash three times with ether, freeze-dry to powder, and identify the structure by mass spectrometry ( Figure 1 ).

[0023] 2. Detect the in vitro ACE inhibitory activity of the 12 polypeptides designed by the present invention. The detection steps are shown in Table 2. Add each reagent to a test tube, preheat in a 37°C water bath for 5 minutes, then add the ACE solution to start the reaction. After 30 minutes, the reaction is completed, and 1 mol / L HCl and / or borate buffer is added to terminate the reaction. Then add 1.7 mL of ethyl acetate to each test tube, shake for 15 seconds, let stand, and after stratification, absorb 1 mL of the ethyl acetate layer into the test tube, put it in an oven at 120°C, evaporate it to dryness, take it out and cool it, and finally add 3 mL of deionized water to the test tube. After fully dissolving, measure the absorbance at a wavelength of 228 nm, and calculate the ACE inhibition rate according to Formula 1; Table 2 ACE inhibitory activity detection steps

[0024] Wherein, a borate buffer solution is prepared: 0.025 mol / L borax aqueous solution is slowly added into 0.1 mol / L boric acid aqueous solution, with stirring, until the pH value of the buffer solution reaches 8.3.

[0025] Preparation of 0.1 UN / mL ACE solution: Dissolve ACE (angiotensin converting enzyme) in the above borate buffer solution to prepare a solution with a concentration of 0.1 UN / mL.

[0026] Prepare 5mmol / L HHL solution: dissolve HHL (Hip-His-Leu) in borate buffer solution to make 5mmol / L.

[0027] Prepare 1 mol / L HCl solution by adding 8.33 mL of concentrated hydrochloric acid to 100 mL of purified water.

[0028] The calculation formula of ACE inhibition rate is: (1) Wherein: A represents the absorbance value of the simultaneous reaction of the peptide with ACE and HHL; B represents the absorbance value of the reaction of ACE solution with HHL; C represents the absorbance value of the reaction of ACE solution with HHL after inactivation, which is used as the blank group.

[0029] 3. IC of peptides 50 Determination: The polypeptide was prepared into solutions of 0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.6 mg / mL, 1.2 mg / mL and 2.0 mg / mL, respectively, and the absorbance was measured by ultraviolet spectrophotometer at 228 nm. The ACE inhibitory activity was calculated according to formula 1, and a curve was plotted with the sample concentration as the abscissa and the ACE inhibitory activity as the ordinate to obtain a regression equation; According to IC 50 Definition and solving IC from quadratic regression equation 50 The specific values ​​are shown in Table 3: Table 3 ACE inhibitory activity of peptides tested in vitro

[0030] Among them, IC 50 It is defined as: the peptide concentration required when the activity of ACE is inhibited to 50%; As shown in Table 3, the IC 50 The smallest value indicates the strongest ACE inhibitory activity. The present invention only displays three peptides with good ACE inhibitory activity, which is convenient for subsequent simulation experiments and in vivo experiments to select target peptides. The IC values ​​of the remaining synthetic peptides are 50The numerical ranges are all greater than 1000 μM, that is, the ACE inhibitory activity is weak, the effect is not ideal, there is no practical application value, and it has no reference significance. Considering the experimental cost, the present invention simulates the docking of the above three polypeptides and focuses on the in vivo activity of the LHLPLLVP polypeptide.

[0031] 4. Mechanism of Peptide Inhibition of ACE Activity Molecular simulation software was used to study the molecular interaction between ACE and peptides and predict their binding mode and affinity. The three-dimensional structure of ACE protein was downloaded from the PDB database, PDB code: 1O861O8A. The protein structure was processed with Mgtools1.5.6 and saved after hydrogenation, dehydration, charge calculation, and merging of non-polar hydrogen. The four peptide sequence structures identified by QExactive HF mass spectrometer (see Figure 1 ), Chemidraw 14.0 was used to draw the structure of the peptide molecule, and the energy was minimized and saved using Mgtools1.5.6. Discovery Studio 2016 software was used for docking simulation. A 25*25*25 box was constructed with the active site of the protein (center x=43.817, center y=38.308, center z=46.452) as the center. The peptide molecular structure was flexible and the Vina program was used to perform molecular simulation of the peptide binding to ACE (PDB1O8A).

[0032] Table 4 Molecular mimicking peptides binding to ACE (PDB1O8A)

[0033] As shown in Table 4, simulation experiments have shown that the three polypeptides can theoretically interact with ACE, but the binding sites are different. According to the simulation flexible docking principle, the software will match the interaction sites to the maximum extent. Therefore, the simulation data is only a theoretical inference, and the actual in vitro activity experimental data must be used as the main reference. The in vitro activity test results shown in Table 3 show that the LHLPLLVP polypeptide has the strongest ability to bind to ACE, and the VLLHSLLVVLL polypeptide is the worst, indicating that any synthesized polypeptide can theoretically bind to the ACE active site, but the actual test does not have good ACE inhibitory activity. Taking into account the cost of animal experiments and the impact of differences in the absorption of polypeptides in vivo, the present invention focuses on the LHLPLLVP polypeptide with the strongest inhibitory effect.

[0034] 5. Peptide animal experiments Even if the polypeptide has good in vitro ACE inhibitory activity, it is affected by many factors such as gastrointestinal digestion and absorption, transmembrane transport, intestinal flora environment, vascular endothelial aggregation, etc., which will lead to significantly different hypotensive effects in vivo. Therefore, the present invention verifies the hypotensive effect of the LHLPLLVP polypeptide provided by the present invention in vivo based on animal experiments on the hypotensive activity of the polypeptide, as follows: 30 SPF-grade SHR rats were selected and divided into 5 experimental groups: model control group, positive control group (10 mg / kg captopril), polypeptide low-dose group (10 mg / kg), polypeptide medium-dose group (20 mg / kg), polypeptide high-dose group (30 mg / kg); and 6 Wistar-Kyoto (WKY) rats were used as the normal control group.

[0035] After one week of adaptive feeding, the normal control group and the model control group were given normal saline. The other groups began to be given long-term medication by oral gavage for 8 weeks, once a day, with the dose of captopril 10 mg / kg, low-dose polypeptide group 10 mg / kg, medium-dose polypeptide group 20 mg / kg, and high-dose polypeptide group 30 mg / kg.

[0036] The systolic blood pressure (SBP) and diastolic blood pressure (DBP) of rats were measured 2 hours after oral administration every week. The results are shown in Table 5: Table 5 Effects of LHLPLLVP peptide administration on SBP and DBP in rat tail artery

[0037] As shown in the results of Table 5, after the positive control group was fed with captopril (a classic antihypertensive drug), the SBP and DBP of the rats decreased by 13.5 mmHg and 17.5 mmHg, respectively. After feeding the LHLPLLVP polypeptide, the high-dose group showed that the SBP and DBP of the rats decreased by 8.25 mmHg and 10.18 mmHg, respectively. Although it could not achieve the effect of classic antihypertensive drugs, the comparison showed that the LHLPLLVP polypeptide had a good antihypertensive effect. The low-dose group fed with the polypeptide showed that the SBP and DBP of the rats decreased by 6.13 mmHg and 4.26 mmHg, respectively, and still had a blood pressure lowering effect, although it was weaker than the high-dose group. Animal experiments confirmed that the polypeptide LHLPLLVP showed a good antihypertensive effect after multiple steps such as digestion and absorption in the body and regulation of intestinal flora.

[0038] As an amino acid with a clear blood pressure lowering effect, LHLPLLVP polypeptide can be used for special dietary care for patients with hypertension. Goat milk powder refers to milk powder made from goat milk. The volume of fat particles in goat milk is 1 / 3 of that in cow milk, which is conducive to human absorption. Compared with cow milk, it has the significant advantage of low allergenicity. At the same time, it has the effects of warming the stomach and kidney, supplementing calcium, skin care and beauty, and is suitable for people of all ages to drink. However, the existing goat milk powder has a single nutritional component and a narrow range of efficacy, which cannot meet the nutritional and health needs of special consumers. As a carrier with mild properties, goat milk is often added with prebiotics, probiotics, special mineral elements, etc. to prepare milk powder with multiple nutritional functions to meet the diversified needs of consumers. However, there is still a blank in the market for special milk powder products for people with hypertension. The present invention adds the polypeptide LHLPLLVP with a clear blood pressure lowering effect to goat milk to prepare a milk powder product with blood pressure lowering effect, which provides benefits for dietary care for specific populations.

[0039] The invention provides a goat milk powder with blood pressure lowering effect. The goat milk powder is obtained by mixing a polypeptide with an ACE activity inhibiting function with defatted goat milk and freeze-drying the mixture. The amino acid sequence of the polypeptide with an ACE activity inhibiting function is LHLPLLVP.

[0040] The polypeptide is added in the form of a polypeptide distilled water solution, i.e., the concentration of the polypeptide solution is 0.1 mg / mL to 0.5 mg / mL, preferably 0.3 mg / mL. The amount of polypeptide solution added is 0.01 mg / mL to 0.05 mg / mL, more preferably 0.03 mg / mL, based on the volume of skimmed goat milk.

[0041] Glucose may also be added to the goat milk powder, with the added amount of glucose being 1 g / L to 10 g / L, preferably 5 g / L.

[0042] The goat milk powder may also contain an antioxidant, the antioxidant includes sodium D-isoascorbate, the addition amount is 0.01 g / g to 0.1 g / g, preferably 0.07 g / g; The specific steps of the above-mentioned goat milk powder preparation method are as follows: (1) Dissolve LHLPLLVP polypeptide powder (purity>95%) in 40 o C. Prepare the polypeptide solution in distilled water; (2) Add the polypeptide solution to skimmed goat milk, stir and mix thoroughly, and then let stand at room temperature (preferably 40 o C) stirring evenly and leaving at room temperature for 15 minutes) to obtain skimmed goat milk containing polypeptides; vacuum freeze drying (preferably -80°C, 16 hours) to obtain goat milk powder with blood pressure lowering effect.

[0043] Preferably, in order to increase the flavor of goat milk powder, in step (2), glucose is added to the skimmed goat milk containing polypeptides, and the mixture is stirred evenly at 40° C. and then cooled to room temperature. Preferably, in order to extend the shelf life of goat milk powder, an antioxidant is added in step (2) after vacuum freeze-drying.

[0044] The goat milk powder of the present invention can also be added with different additives according to flavor requirements, such as vanillin (<5 mg / 100 mL), citrate, vanilla bean extract or phospholipids, and prepared into goat milk powders with various flavors according to known methods.

[0045] Example 1 A goat milk powder with blood pressure lowering effect is prepared by the following method: (1) Dissolve LHLPLLVP polypeptide powder (purity>95%) in 40 o C distilled water to obtain a 0.3 mg / mL peptide solution.

[0046] (2) Add 1 mL of polypeptide solution to 10 mL of skimmed goat milk (1:10, v / v) for 40 o C was stirred evenly and placed at room temperature for 15 minutes. The ACE inhibitory activity was measured to be 75.8%.

[0047] (3) Add 5g of glucose per liter of goat milk in step (2), 40 o C. Stir well and cool to room temperature.

[0048] (4) freeze-drying the goat milk obtained in step (3) at -80°C for 16 hours to obtain freeze-dried goat milk powder rich in LHLPLLVP polypeptide; (5) Add 0.07 g of antioxidant D-sodium isoascorbate to each gram of freeze-dried goat milk powder in step (4), and pack the mixture in an aluminum foil bag at room temperature to obtain goat milk powder with blood pressure lowering effect.

[0049] The goat milk powder obtained in Example 1 was subjected to sensory, microbiological, and nutrient testing and analysis. The results are shown in Table 6.

[0050] Table 6 Quality detection and analysis of goat milk powder in Example 1

[0051] The goat milk powder obtained in Example 1 was tested for its blood pressure lowering function Dissolve freeze-dried goat milk powder in 40 oC water, stirred evenly, left at room temperature for 5 minutes, and the ACE inhibitory activity was determined to be 71.5%. This proves that the LHLPLLVP polypeptide gives goat milk a highly efficient ACE inhibitory activity after being added to it, and the mixed freeze-dried milk powder still has an ACE inhibitory activity of up to 71.5% after reconstitution, and the sensory quality and nutrients of the milk powder are not affected. Although low-temperature freeze-drying technology will affect the physical properties of components such as protein, fat, and lactose, causing instability and slightly reducing ACE inhibitory activity, the final product goat milk powder still has highly efficient ACE inhibitory activity, that is, blood pressure lowering effect.

[0052] Example 2 A goat milk powder with blood pressure lowering effect is prepared by the following method: (1) Dissolve LHLPLLVP polypeptide powder (purity>95%) in 40 o C distilled water to obtain a 0.5 mg / mL peptide solution.

[0053] (2) Add 1 mL of polypeptide solution to 10 mL of skimmed goat milk (1:10, v / v) for 40 o C was stirred evenly and placed at room temperature for 15 minutes. The ACE inhibitory activity was measured to be 81.7%.

[0054] (3) Add 1g of glucose per liter of goat milk in step (2), 40 o C. Stir well and cool to room temperature.

[0055] (4) freeze-drying the goat milk obtained in step (3) at -80°C for 16 hours to obtain freeze-dried goat milk powder rich in polypeptides; (5) Add 0.01 g of antioxidant D-sodium isoascorbate to each gram of freeze-dried goat milk powder in step (4), and pack the mixture in an aluminum foil bag at room temperature to obtain goat milk powder with blood pressure lowering effect.

[0056] The goat milk powder obtained in Example 2 was tested and analyzed from the aspects of sensory, microbiological, and nutritional substances. The results are shown in Table 7.

[0057] Table 7 Quality analysis of goat milk powder with blood pressure lowering effect

[0058] The goat milk powder obtained in Example 2 was tested for its blood pressure lowering function Dissolve freeze-dried goat milk powder in 40 o C water, stirred evenly, and placed at room temperature for 5 minutes. The ACE inhibitory activity was determined to be 78.2%.

[0059] Example 3 A goat milk powder with blood pressure lowering effect is prepared by the following method: (1) Dissolve LHLPLLVP polypeptide powder (purity>95%) in 40 o C distilled water to obtain a 0.1 mg / mL peptide solution.

[0060] (2) Add 1 mL of polypeptide solution to 10 mL of skimmed goat milk for 40 min. o C was stirred evenly, and allowed to stand at room temperature for 15 minutes. The ACE inhibitory activity was determined by the method of Example 1 and was 69.3%.

[0061] (3) Add 10g of glucose per liter of goat milk in step (2), 40 o C. Stir well and cool to room temperature.

[0062] (4) freeze-drying the goat milk obtained in step (3) at -80°C for 16 hours to obtain freeze-dried goat milk powder rich in polypeptides; (5) Add 0.1 g of antioxidant D-sodium isoascorbate to each gram of freeze-dried goat milk powder in step (4), and pack the mixture in an aluminum foil bag at room temperature to obtain goat milk powder with blood pressure lowering effect.

[0063] The goat milk powder obtained in Example 3 was tested and analyzed in terms of sensory, microbiological, and nutritional substances. The results are shown in Table 8.

[0064] Table 8 Quality detection and analysis of goat milk powder in Example 3

[0065] The goat milk powder obtained in Example 3 was tested for its blood pressure lowering function Dissolve freeze-dried goat milk powder in 40 o C water, stirred evenly, and placed at room temperature for 5 minutes. The ACE inhibitory activity was determined to be 65.15%.

[0066] Comparative Example 1: A goat milk powder with blood pressure lowering effect is prepared by the following method: (1) Weigh 0.3 mg of LHLPLLVP polypeptide powder (purity > 95%).

[0067] (2) Add 0.3 mg of peptide powder to 10 mL of skim goat milk for 40 min. o C was stirred evenly and placed at room temperature for 15 minutes. The ACE inhibitory activity was determined to be 71%.

[0068] (3) Add 5g of glucose per liter of goat milk in step (2), 40 o C. Stir well and cool to room temperature.

[0069] (4) freeze-drying the goat milk obtained in step (3) at -80°C for 16 hours to obtain freeze-dried goat milk powder rich in LHLPLLVP polypeptide; (5) Add 0.07 g of antioxidant D-sodium isoascorbate to each gram of freeze-dried goat milk powder in step (4), and pack the mixture in an aluminum foil bag at room temperature to obtain goat milk powder with blood pressure lowering effect.

[0070] The goat milk powder prepared in Comparative Example 1 was tested and analyzed from the aspects of sensory, microbiological, and nutritional substances. The results are shown in Table 9.

[0071] Table 9 Quality test analysis of goat milk powder obtained in Comparative Example 1

[0072] The goat milk powder prepared in Comparative Example 1 was tested for its blood pressure lowering function Dissolve freeze-dried goat milk powder in 40 o C water, stirred evenly, and placed at room temperature for 5 minutes. The ACE inhibitory activity was determined to be 67.75%.

[0073] When LHLPLLVP polypeptide is added to goat milk in powder form, it gives it an ACE inhibitory activity of 71%. After reconstitution, the mixed freeze-dried milk powder still has an ACE inhibitory activity of 67.75%, and the sensory quality and nutrients of the milk powder are not affected. Adding polypeptides to goat milk in powder form will reduce the ACE inhibitory activity because the solubility and dispersibility of polypeptide powder in the emulsion are affected, resulting in a decrease in ACE inhibitory activity. In addition, low-temperature freeze-drying technology will affect the physical properties of components such as protein, fat, and lactose, causing instability, so the final product goat milk powder has an ACE inhibitory activity of 67.75%. Adding LHLPLLVP polypeptide to goat milk in the form of a solution can effectively avoid the reduction of ACE inhibitory activity caused by factors such as solubility and dispersibility. The final product goat milk powder has an ACE inhibitory activity of up to 71.5% after reconstitution, and is a goat milk powder with high blood pressure lowering function.

[0074] Comparative Example 2: Preparation and Detection of Goat Milk Powder without Peptide 1. Preparation of goat milk powder without polypeptide (1) Add 5g of glucose to each liter of skim goat milk, 40 o C. Stir well and cool to room temperature.

[0075] (2) freeze-drying the goat milk obtained in step (1) at -80°C for 16 hours to obtain freeze-dried goat milk powder; (3) Add 0.07 g of antioxidant D-sodium isoascorbate to each gram of freeze-dried goat milk powder in step (2), and pack the mixture in an aluminum foil bag at room temperature to obtain goat milk powder.

[0076] 2. Quality inspection The results of the sensory, microbial and nutrient tests are shown in Table 10.

[0077] Table 10 Quality analysis of freeze-dried goat milk powder

[0078] 3. Blood pressure lowering efficacy test Dissolve freeze-dried goat milk powder in 40 o C water, stirred evenly, and placed at room temperature for 5 minutes. The ACE inhibitory activity was measured to be 0.

[0079] This indicates that goat milk powder itself does not have the effect of lowering blood pressure, and needs to be endowed with the effect of lowering blood pressure by adding polypeptides with ACE inhibitory activity. Examples 1 to 3 illustrate that different ACE inhibitory peptides added to goat milk at different concentrations or in different ways produce completely different ACE inhibitory effects, and only the LHLPLLVP polypeptide can endow goat milk with good ACE inhibitory activity, thereby preparing goat milk powder with high-efficiency blood pressure lowering effect.

[0080] In summary, the present invention synthesizes a LHLPLLVP polypeptide with the function of inhibiting ACE activity through rational design, and proves through in vivo and in vitro experiments that the LHLPLLVP polypeptide is mixed with goat milk and freeze-dried to prepare a functional goat milk powder. The functional goat milk powder has strong ACE inhibitory activity and blood pressure lowering effect, has low production cost, is not limited by resources, has little environmental pollution, can be mass-produced, and the product is safe, and has broad application prospects in the food industry.

Claims

1. A LHLPLLVP polypeptide, characterized in that The polypeptide has the function of inhibiting ACE activity.

2. A composition, characterized in that The composition comprises the LHLPLLVP polypeptide according to claim 1 and a carrier acceptable in medicine, food or health care products.

3. Use of the LHLPLLVP polypeptide according to claim 1 or the composition according to claim 2 in the preparation of a product for treating and / or preventing hypertension.

4. A food having the effect of lowering blood pressure, characterized in that: The food is added with LHLPLLVP polypeptide, and the LHLPLLVP polypeptide has the function of inhibiting ACE activity.

5. A goat milk powder with blood pressure lowering effect, characterized in that: The LHLPLLVP polypeptide is added into goat milk and freeze-dried to obtain the polypeptide, wherein the LHLPLLVP polypeptide has the function of inhibiting ACE activity.

6. The goat milk powder with blood pressure lowering effect according to claim 5, characterized in that: The LHLPLLVP polypeptide is added in the form of a distilled water solution of the polypeptide, the concentration of the LHLPLLVP polypeptide aqueous solution is 0.1 mg / mL to 0.5 mg / mL, and the amount of the LHLPLLVP polypeptide aqueous solution added is 0.01 mg / mL to 0.05 mg / mL based on the volume of goat milk.

7. The goat milk powder with blood pressure lowering effect according to claim 5, characterized in that: The purity of the LHLPLLVP polypeptide is greater than 95%.

8. The goat milk powder with blood pressure lowering effect according to claim 5, characterized in that: The goat milk is skimmed goat milk.

9. The goat milk powder with blood pressure lowering effect according to claim 5, characterized in that: The raw materials also include glucose and an antioxidant, wherein the amount of glucose added is 1 g / L to 10 g / L, and the amount of the antioxidant added is 0.01 g / g to 0.1 g / g.

10. The method for preparing goat milk powder with blood pressure lowering effect according to claim 6, characterized in that: The specific steps are as follows: Adding the LHLPLLVP polypeptide aqueous solution into goat milk, stirring and standing, to obtain polypeptide-containing goat milk; The polypeptide-containing goat milk is vacuum freeze-dried to obtain goat milk powder with blood pressure lowering effect.

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