Alpha-amylase inhibitory peptide and application thereof

Abstract

The invention belongs to the field of biological pharmacy, and relates to an alpha-amylase inhibitory peptide and application thereof. Specifically, the provided unreported peptide fragment LDKFLWT can effectively inhibit the activity of alpha-amylase, and animal experiments prove that the newly designed polypeptide has the effects of reducing blood sugar, reducing blood fat, improving insulin resistance and the like through polypeptide intervention; compared with a traditional hypoglycemic drug, the alpha-amylase inhibitory peptide disclosed by the invention has remarkable safety.

Description

Technical Field

[0001] The present invention belongs to the field of biopharmaceuticals and relates to an α-amylase inhibitory peptide and its application. Background Art

[0002] Diabetes and its related metabolic diseases have become a major public health challenge globally, especially type 2 diabetes (T2DM), whose core features are insulin resistance and postprandial hyperglycemia. Insulin resistance refers to the reduced efficiency of insulin in promoting glucose uptake and utilization, resulting in the inability of blood glucose to be effectively absorbed and utilized by cells, thus leading to elevated blood glucose levels. Postprandial hyperglycemia refers to the rapid increase in blood glucose levels after eating. A long-term hyperglycemic state can cause severe damage to important organs such as the cardiovascular system, kidneys, and retina, increasing the risk of diabetic complications. α-Amylase rapidly breaks down starch into absorbable sugars, leading to a rapid increase in blood glucose levels, affecting blood glucose homeostasis, increasing the secretion burden of insulin, and thus exacerbating insulin resistance. Therefore, inhibiting the activity of α-amylase has become one of the important strategies for regulating postprandial blood glucose levels.

[0003] α-Amylase inhibitors inhibit starch digestion by competitively binding to the active sites of α-amylase in saliva and pancreatic juice, causing undigested carbohydrates to be transferred to the posterior segment of the intestine for slow-release absorption, thereby extending the glucose absorption time axis and significantly flattening the postprandial blood glucose fluctuation curve. Currently, chemical α-amylase inhibitors such as acarbose, voglibose tablets, and miglitol tablets are widely used clinically. Although their hypoglycemic effects are significant, long-term use can cause weight gain, gastrointestinal discomfort (such as bloating and diarrhea), and potential liver and kidney toxicity. In contrast, α-amylase inhibitory peptides have become a hot topic in the research and development of functional hypoglycemic foods and drugs due to their high safety and strong targeting. For example, plant protein functional peptides exhibit certain inhibitory activity, but their stability and bioavailability still need to be improved. In addition, the inhibitory rate of some inhibitory peptides is relatively low, only about 35%, limiting their application value.

[0004] To improve activity and stability, some studies have attempted to complex inhibitory peptides with plant polyphenols, but the complex process of this method is complex and the improvement of thermal stability is limited. Although composition design (such as the soybean peptide - selenium-enriched yeast system in CN 118403140 A) can enhance the hypoglycemic effect through synergistic effects, its formula is complex. Therefore, there is an urgent need to design a novel short peptide α-amylase inhibitor with high inhibitory activity, excellent stability, and multiple physiological functions to promote its wide application in the fields of clinical treatment and functional foods. Summary of the Invention

[0005] To make up for the deficiencies of the prior art, the present invention provides the following technical solutions, specifically:

[0006] The first aspect of the present invention is to provide a polypeptide molecule, characterized in that the polypeptide molecule can inhibit α - amylase activity, the polypeptide molecule contains LDKFLWT, and the length of the polypeptide molecule is less than 10 amino acids; preferably, the polypeptide molecule is characterized in that the polypeptide molecule is LDKFLWT.

[0007] The second aspect of the present invention is to provide an α - amylase inhibitor, characterized in that the inhibitor contains the polypeptide molecule described in the first aspect.

[0008] The third aspect of the present invention is to provide a pharmaceutical composition for treating diabetes, characterized in that the pharmaceutical composition contains the polypeptide molecule described in the first aspect.

[0009] Further, the pharmaceutical composition further includes a pharmaceutically acceptable carrier, and the administration methods of the drug include oral administration, injection, and gavage.

[0010] Further, the administration dose of the polypeptide molecule is 80 - 120 mg / kg body weight.

[0011] The fourth aspect of the present invention is to provide the application of the polypeptide molecule described in the first aspect in the preparation of a drug for treating diabetes.

[0012] Further, the pharmaceutical composition further includes a pharmaceutically acceptable carrier, and the administration methods of the drug include oral administration, injection, and gavage.

[0013] Further, the administration dose of the polypeptide molecule is 80 - 120 mg / kg body weight.

[0014] The fifth aspect of the present invention is to provide the application of the polypeptide molecule described in the first aspect in the preparation of a drug for treating hyperlipidemia.

[0015] Further, the pharmaceutical composition further includes a pharmaceutically acceptable carrier, and the administration methods of the drug include oral administration, injection, and gavage.

[0016] Further, the administration dose of the polypeptide molecule is 80 - 120 mg / kg body weight.

[0017] The beneficial effects of the present invention include:

[0018] 1. The unreported peptide segment LDKFLWT provided in the present application has the advantages of being safe, non - toxic, and having no side effects, and can effectively inhibit α - amylase activity and regulate post - meal blood glucose, thus playing a certain role in alleviating diabetes and its complications.

[0019] 2. The α-amylase inhibitory peptide involved in the present invention can be used as the core active ingredient, and a series of functional products for regulating blood pressure and blood sugar can be prepared by adding appropriate excipients. These products can meet diverse administration requirements and are applicable to the population of type 2 diabetes patients. Compared with traditional hypoglycemic drugs, the α-amylase inhibitory peptide of the present invention has remarkable safety and no adverse reactions.

[0020] 3. Based on a diabetic mouse model induced by a combination of high-fat diet (HFD) and streptozotocin (STZ), the present invention proves that the newly designed polypeptide has effects such as hypoglycemic, hypolipidemic, and improving insulin resistance through intervention with the polypeptide. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Molecular docking result diagram: Figure 1A , polypeptide B1; Figure 1B , polypeptide B2; Figure 1C , polypeptide B3; Figure 1D , polypeptide B4.

[0022] Figure 2 Polypeptide high performance liquid chromatography results.

[0023] Figure 3 Polypeptide mass spectrum.

[0024] Figure 4 α-Amylase inhibitory activity.

[0025] Figure 5 Schematic diagram of animal experiments.

[0026] Figure 6 Monitoring of the therapeutic effect of polypeptide intervention on a diabetic mouse model: A, body weight; B, water intake; C, food intake; D, fasting blood glucose; E, OGTT test results; F, area under the OGTT curve; G, ITT test results; H, area under the ITT curve; I, total cholesterol TC concentration; J, triglyceride TG concentration; K, high density lipoprotein HDL-C concentration; L, alanine aminotransferase ALT activity; M, aspartate aminotransferase AST activity; N, pathological sections of pancreas and liver. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following further elaborates on the concept and technical effects generated by the present invention in combination with specific embodiments to fully understand the purpose, features, and effects of the present invention. The methods are all conventional methods unless otherwise specified. The materials can all be obtained from public commercial channels unless otherwise specified. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0028] Design and Active Site Analysis of Polypeptide in Example 1

[0029] Based on the newly designed bioactive polypeptide sequence, the online tool AlphaFold3 (https: / / alphafoldserver.com / ) was used to predict the three-dimensional structure, thereby obtaining the polypeptide spatial conformation. Then, the high-resolution crystal structure of human α-amylase (PDB ID: 1HNY; resolution: ) was obtained from the PDB database (https: / / www.rcsb.org / ) and used as the receptor protein. The receptor protein was dehydrated, and the co-crystallized ligands and heterologous ions were removed using Discovery Studio. The structure was preprocessed using the Pymol molecular visualization system, dehydrated, and hydrogenated to finally obtain a complete α-amylase protein molecular model. In the open-source molecular docking system AutoDock Vina, the preprocessed α-amylase and polypeptide were defined as the receptor and ligand, respectively, and then molecular docking was performed. According to the docking results, the affinity between the receptor and ligand was analyzed, and the best conformation in the docking results was screened based on the binding free energy (ΔG). Discovery Studio and Pymol were used for analysis to systematically analyze the characteristics of the polypeptide ligand-α-amylase receptor interface. By calculating parameters such as van der Waals surface contact area, hydrogen bond network, salt bridge interaction, and hydrophobic interaction, the key binding residues were identified. The amino acid residues that formed stable interactions within the binding pocket were visually characterized to clarify the molecular basis of polypeptide inhibition of α-amylase activity. The molecular docking results are shown in Figure 1. FMFPH interacted with amino acid residues such as Gln63, Leu165, His305, Tyr151, His299, Ala198, and His201 of amylase through hydrogen bonds, van der Waals forces, π-stacking, etc. PFQQWH interacted with amino acid residues such as Thr163, His201, Asp197, Asp300, His305, Trp58, Leu162, Trp59, and Tyr151 of amylase through hydrogen bonds, van der Waals forces, π-stacking, etc. TPWFF interacted with amino acid residues such as His201, Ile235, Tyr62, and Leu162 of amylase through hydrogen bonds, van der Waals forces, π-stacking, etc. LDKFLWT interacted with amino acid residues such as Thr163, Trp59, His305, Ala307, His201, Tyr151, His299, and Tyr62 of amylase through hydrogen bonds, van der Waals forces, π-stacking, etc.

[0030] Prediction of Polypeptide Bioactivity, Toxicity, and Physicochemical Properties in Example 2

[0031] The online tool PeptideRanker (http: / / distilldeep.ucd.ie / PeptideRanker / ) was used to predict the biological activity. The results showed that the biological activities of the 4 short peptides described in this application were all greater than 0.5, safe without toxic side effects, easily digestible and absorbable, and had the potential to be developed into α-amylase inhibitors. Using the AutoDockTools molecular docking software, the binding energies of the 4 short peptides FMFPH, PFQQWH, TPWFF, and LDKFLWT were -8.5 kcal / mol, -9.8 kcal / mol, -8.6 kcal / mol, and -7.4 kcal / mol respectively. The predicted molecular weights were 677.88 Da, 842.01 Da, 696.86 Da, and 922.19 Da respectively. The specific peptide prediction results are shown in Table 1.

[0032] Table 1 Results of peptide segments with good docking effects with α-amylase in virtual screening

[0033]

[0034] Example 3 Synthesis of Polypeptides

[0035] The polypeptide synthesis work involved in this application was completed by Nanjing Genscript Biotech Co., Ltd. through solid-phase peptide synthesis (SPPS). The purity of all polypeptide products was verified by high-performance liquid chromatography (HPLC) to be greater than 95%. SPPS is to couple amino acids to the resin in sequence to form a peptide chain. After the sequence synthesis is completed, first deprotect the N-terminal Fmoc protecting group, and then (after completing the N-terminal modification) deprotect the side-chain protecting groups to cleave the peptide segment from the resin. The standardized process is as follows: (1) Resin activation: Take an appropriate amount of modified resin, add the previously prepared amino acid solution to the resin, and react for a period of time; (2) Remove Fmoc: After adding the Pip / DMF solution for a period of time, vacuum filter to remove the solvent; (3) Washing: Add DMF to the resin (washing step), and vacuum filter to remove the solvent; (4) Resin detection: Put the detection reagents A and B and an appropriate amount of resin into a test tube, place the test tube in a high-temperature water bath for 3 - 5 seconds, and check the color change of the resin. If the color of the resin changes, the Fmoc group has been successfully removed; (5) Amino acid condensation: Add the prepared amino acid solution to the resin. Then add the coupling reagent, shake well for a period of time, and vacuum filter to remove the solvent; (6) Repeat steps 2 - 5 until the synthesis of the last amino acid is completed.

[0036] The purity of FMFPH was 96.75( Figure 2 B1, Table 2), and the molecular weight identified by mass spectrometry was 677.4 Da( Figure 3 B1). The purity of PFQQWH was 99.77%(Figure 2 B2, Table 3), the molecular weight identified by mass spectrometry was 842 Da ( Figure 3 B2). The purity of TPWFF was 99.83% ( Figure 2 B3, Table 4), the molecular weight identified by mass spectrometry was 696.5 Da ( Figure 3 B3). The purity of LDKFLWT was 95.78% ( Figure 2 B4, Table 5), the molecular weight identified by mass spectrometry was 922.2 Da ( Figure 3 B4). The purity and molecular weight of the oligopeptide synthesized by the solid-phase synthesis method met the requirements.

[0037] Table 2 FMFPH High-performance Liquid Chromatography Peak Table

[0038]

[0039] Table 3 PFQQWH High-performance Liquid Chromatography Peak Table

[0040]

[0041] Table 4 TPWFF High-performance Liquid Chromatography Peak Table

[0042]

[0043] Table 5 LDKFLWT High-performance Liquid Chromatography Peak Table

[0044]

[0045] Example 4 In Vitro Verification of α-Amylase Inhibitory Activity

[0046] Prepare 1 U / mL α-amylase solution and 1% (w / w) starch solution using PBS buffer with pH 6.9 and a concentration of 20 mmol / L. Pipette 20 μL of the sample solution with a concentration of 5 mg / mL and 10 μL of 1 U / mL α-amylase solution into a centrifuge tube, and react on a shaker at 37 °C for 15 min. Subsequently, add 500 μL of the pretreated starch solution to the reaction system and react on a shaker at 37 °C for 5 min. Finally, add 600 μL of the reaction termination solution DNS and perform a boiling water bath for 15 min. After the reaction is completed, cool to room temperature and measure the absorbance at a wavelength of 540 nm.

[0047] α-Amylase inhibition rate calculation formula:

[0048]

[0049] The 4 short peptides described in the present invention all had good α-amylase inhibitory activity at a concentration of 5 mg / mL (see Figure 4), where the α - amylase inhibitory activities of B2: PFQQWH and B4: LDKFLWT are both greater than 50%, showing good characteristics of blood glucose - lowering function. Therefore, two polypeptides B2 and B4 with high α - amylase inhibitory activity are obtained for the next in - vivo experiment screening.

[0050] Example 5 Animal Experiment

[0051] Six - week - old male C57BL / 6J mice (purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd.) were selected as the subjects of the animal experiment. They were adaptively fed for three days, and the breeding environment was 22 ± 2 °C, humidity 50% - 60%, and a 12 - hour light - dark cycle. Five mice were randomly selected as the normal control group and fed with ordinary feed, while the remaining mice were fed with a high - fat diet (Beijing Huafukang Biotechnology Co., Ltd., product number: H10060), and the energy ratio of this feed was 60% fat. During the experiment, the body weight and blood glucose level of the mice were confirmed to ensure that the health status of the animals was suitable for the experiment.

[0052] After six weeks of high - fat feeding, the mice developed insulin resistance. Streptozotocin (STZ) was dissolved in sodium citrate buffer (pH 4.5) and intraperitoneally injected at a dose of 50 mg / kg for 3 consecutive days. The mice in the normal control group were injected with an equal volume of 0.1 mol / L citric acid buffer. 72 hours after the last injection of STZ, the blood glucose of the mice's tail vein was detected using a blood glucose meter. When the blood glucose level was ≥ 11.1 mmol / L, the mice were successfully induced into a diabetes model. The schematic diagram of the animal experiment is as Figure 5 shown, and the grouping and intervention methods are shown in Table 6.

[0053] Table 6 Grouping and Intervention Methods of Mice

[0054]

[0055]

[0056] 1) Sample Collection

[0057] During the model construction stage, the mice's tails were pinched daily for adaptability training to reduce the stress - induced blood glucose fluctuations caused by blood sampling operations. After 3 weeks of polypeptide intervention, the 6 - hour fasting blood glucose level, body weight, food intake, and water intake of the mice were measured. The blood sampling method was uniformly standardized as minimally invasive puncture of the tail vein.

[0058] This application successfully established a T2DM model. Specifically, compared with the mice in the normal control group, the fasting blood glucose value of the mice in the T2DM model group increased significantly ( Figure 6 D). As the core pathological feature of T2DM, the chronic hyperglycemic state leads to weight loss in experimental animals by accelerating protein catabolism and lipid peroxidation reactions (see Figure 6A). The body weights of the mice in the T2DM model group showed a significant decrease (p < 0.05), while the body weights of the mice in the positive control and polypeptide intervention groups significantly rebounded compared with the model group (p < 0.05), indicating that the polypeptide preparation could effectively reverse the metabolic wasting caused by T2DM. After 3 weeks of intervention treatment, the body weights of the mice were comparable to those of the positive control group. The main symptoms of hyperglycemia are polydipsia and polyphagia. After polypeptide intervention, the symptoms of polydipsia and polyphagia in the mice of the positive control and polypeptide intervention groups were significantly improved compared with the model group (see Figure 6 B and C).

[0059] The results showed that after treatment with different intervention regimens, both the positive drug group and the polypeptide B4 group showed significant blood glucose regulation effects. The polypeptide B4 intervention group showed an effect comparable to that of the positive drug level. The results indicated that the polypeptide B4 of the present invention had a significant effect on reducing the fasting blood glucose value of mice with T2DM.

[0060] 2) GTT, ITT

[0061] After 3 weeks of polypeptide intervention treatment, an oral glucose tolerance test (OGTT) was carried out on the mice. A 20% glucose solution (the solvent was physiological saline) at 2 g / kg was intragastrically administered, and the blood glucose values at 5 time points of 0, 30, 60, 90, and 120 min were measured and recorded.

[0062] At the end of the experiment, an insulin tolerance test (ITT) was carried out. The mice were fasted for 4 h, and the fasting basal blood glucose value was measured by collecting blood from the tail vein. Insulin at 0.75 U / kg was intraperitoneally injected, and the blood glucose values were measured at 15, 30, 60, 90, and 120 min after injection, respectively.

[0063] The changes in GTT and its AUC of the mice in each experimental group (see Figure 6 E and F). Within 15 min after the 20% glucose solution was given to the mice in each group, the blood glucose rapidly increased and reached the highest level. The blood glucose level gradually decreased from 15 to 120 min and finally basically returned to the blood glucose level at 0 min. Compared with the mice in the normal control group, the blood glucose of the mice in the T2DM model group decreased slowly, and within 0 - 120 min, the blood glucose concentration was significantly higher than that of the normal control group (p < 0.05). The curvature of the glucose tolerance curve of the mice in the polypeptide intervention group and the positive control group was depressed and lower than that of the T2DM model group within 0 - 120 min. Compared with the mice in the normal control group, the AUC of the mice in the T2DM model group was significantly increased (p < 0.05). Compared with the mice in the T2DM model group, the AUC of the mice in the polypeptide intervention group and the positive control group were both significantly decreased (p < 0.05). Among them, the AUC of the mice in the positive control group and the polypeptide B4 intervention group was basically the same.

[0064] The changes in ITT and its AUC of the mice in each experimental group (see Figure 6Groups G and H). The blood glucose level of the normal control group mice was the lowest and relatively stable within 120 min. The blood glucose level of the T2DM model group mice was the highest. Compared with the T2DM model group mice, the blood glucose levels of the polypeptide intervention group and the positive control group mice decreased compared with the T2DM model group, and the positive control group was close to the normal control group, and the polypeptide B4 intervention group tended to be the normal control group. Compared with the normal control group mice, the AUC of the T2DM model group mice was significantly increased (p < 0.05). Compared with the T2DM model group mice, the AUC of the polypeptide intervention group and the positive control group mice were both significantly decreased (p < 0.05). Among them, the AUC of the polypeptide B4 intervention group mice was significantly lower than that of the polypeptide B2 intervention group (p < 0.05).

[0065] The results showed that: the impaired glucose tolerance and insulin resistance of the mice were significantly improved after polypeptide intervention, reaching an effect basically equivalent to that of the positive control. After drug intervention, by comparing the blood glucose change curves and the area under the curve (AUC) of diabetic mice in the OGTT and ITT experiments, it could be judged whether the drug could improve the glucose metabolism of the mice, so as to preliminarily evaluate its hypoglycemic effect. The results showed that the AUC of the intervention group mice and the positive control group mice were significantly decreased compared with the T2DM model group (p < 0.01). Among them, the AUC of polypeptide B4 was equivalent to that of the positive control group in the OGTT experiment. It indicated that polypeptide LDKFLWT had a good effect in improving glucose tolerance and enhancing insulin sensitivity.

[0066] 3) Serum-related indicators

[0067] Take the blood samples of the mice into anticoagulation tubes, place them at room temperature for 2 - 3 h, centrifuge at 4℃ and 1000×g for 10 min, and take the upper light yellow serum and store it at -80℃ for later use. Use the detection kits from Nanjing Jiancheng to detect the levels of triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in each group, and statistically analyze whether there are significant differences in each group.

[0068] The effects on the blood lipid levels of the mice were as Figure 6 I to Figure 6As shown in M. The serum TC and TG levels in the T2DM model group of mice were the highest, being 7.51 mmol / L and 2.53 mmol / L respectively. Compared with the T2DM model group, the polypeptide intervention group and the positive control group showed significant decreases in these lipids (p < 0.05). In addition, polypeptide B4 could reduce the serum TC and TG levels to nearly 5.38 mmol / L and 0.58 mmol / L respectively. The serum HDL-C level in the T2DM model group of mice was the lowest, being 0.66 mmol / L. The HDL-C levels in the polypeptide intervention group and the positive control group were significantly increased compared with the T2DM model group. Similarly, the serum ALT and AST levels in the T2DM model group of mice were the highest, being 91.54 U / L and 71.72 U / L respectively. The serum ALT and AST levels in the polypeptide B4 intervention group and the positive control group of mice were significantly lower than those in the T2DM model group (p < 0.05), and were approaching those in the normal model group of mice.

[0069] The results showed that the interventions of the positive drug and polypeptide B4 could significantly reduce the levels of TC, TG, ALT and AST in the serum of mice, and increase the HDL-C level, thus being beneficial to improving dyslipidemia, promoting the balance of glucose and lipid metabolism, and further contributing to the improvement of diabetic symptoms.

[0070] 4) Pathological sections of animal experiments

[0071] Preparation of pathological sections: The pancreatic and liver tissues were immersed in 4% paraformaldehyde fixative overnight. The pancreatic and liver samples stored in the fixative were washed three times with PBS buffer for 10 min each time, and then dehydrated and embedded after gradient elution with 30%, 50%, and 70% ethanol for 5 min each time. The dehydration and embedding steps are shown in the following table:

[0072] Table 7 Embedding steps of pancreatic and liver tissues

[0073]

[0074] After embedding, the samples were stored at 4°C for 1 day and then sectioned. The pancreatic and liver wax blocks were cut into 5-μm paraffin sections and baked at 65°C for 2 h for subsequent staining operations. The dewaxing operation of the paraffin sections before staining is shown in the following table:

[0075] Table 8 Dewaxing steps of pancreatic and liver sections

[0076]

[0077] All sections were stained with hematoxylin-eosin: ① Stain with hematoxylin solution for 1 minute and 30 seconds. After bluing with running tap water for 3 minutes, terminate the bluing with distilled water; ② Quickly immerse in 95% ethanol for 30 seconds to wash away excess floating color; ③ Place in eosin staining solution for 20 seconds, and quickly immerse in 95% ethanol for 30 seconds to wash away excess floating color; ④ Dehydrate in 95% ethanol and 100% ethanol in sequence, and quickly immerse in each grade for 1 minute to prevent decolorization; ⑤ Transparify in xylene Ⅰ and xylene Ⅱ in sequence, and immerse in each grade for 10 minutes; ⑥ Mount the sections with neutral balsam, and observe under an optical microscope after drying.

[0078] The staining results of the pancreas and liver of mice in each group are shown in Figure 6 N. In the normal control group of mice, the islet structure was clear and the cells were arranged neatly. In the T2DM model group of mice, the islet structure was disordered and the cells were arranged irregularly. The islet structure of mice in the polypeptide intervention group and the positive control group was improved and the cells were arranged relatively neatly. In particular, the islet structure of mice in the polypeptide B4 intervention group and the positive control group was close to normal. In the T2DM model group of mice, there was severe hepatocyte damage, including focal necrosis, inflammatory cell infiltration and lipid droplet accumulation. In the normal model group of mice, the liver structure and hepatocyte morphology were normal. The liver of mice in the polypeptide intervention group and the positive control group almost returned to normal, with reduced focal necrosis, inflammatory cell infiltration and lipid droplet accumulation.

[0079] Based on the results of animal experiments, polypeptide B4 can effectively reverse metabolic wasting, improve polyphagia and polydipsia symptoms, delay the development of diabetes, can significantly improve impaired glucose tolerance and insulin resistance, and can reduce blood lipids, repair the structure of islet cells and hepatocytes and maintain homeostasis. This result provides a new idea for the dietary intervention method of diabetic patients in clinical practice and has important significance.

[0080] The embodiments described above are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

Claims

1. A polypeptide molecule, characterized in that The polypeptide molecule can inhibit the activity of alpha-amylase, the polypeptide molecule comprises LDKFLWT, and the length of the polypeptide molecule is less than 10 amino acids.

2. The polypeptide molecule according to claim 1, characterized in that The polypeptide molecule is LDKFLWT.

3. An α-amylase inhibitor, characterized in that The inhibitor comprises the polypeptide molecule according to claim 1 or 2.

4. The inhibitor according to claim 3, characterized in that The inhibitor also includes a pharmaceutically acceptable carrier.

5. A pharmaceutical composition for treating diabetes, characterized in that: The pharmaceutical composition contains the polypeptide molecule according to claim 1 or 2.

6. The pharmaceutical composition according to claim 5, characterized in that The pharmaceutical composition also includes a pharmaceutically acceptable carrier, and the administration method of the drug includes oral administration, injection, and intragastric administration.

7. The pharmaceutical composition according to claim 5 or 6, characterized in that The dosage of the polypeptide molecule is 80-120 mg / kg body weight.

8. Use of the polypeptide molecule according to claim 1 or 2 in the preparation of a drug for treating diabetes, characterized in that: The dosage of the polypeptide molecule is 80-120 mg / kg body weight.

9. The use according to claim 8, characterized in that: The drug group also includes a pharmaceutically acceptable carrier, and the drug administration method includes oral administration, injection, and intragastric administration.

10. Use of the polypeptide molecule according to claim 1 or 2 in the preparation of a drug for treating hyperlipidemia, characterized in that: The dosage of the polypeptide molecule is 80-120 mg / kg body weight.

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