Alpha-glucosidase inhibiting peptides and uses thereof

Abstract

The application belongs to the field of biological pharmacy and relates to an alpha-glucosidase inhibiting peptide and application thereof. Specifically, the unreported peptide segment FPKIPPP can effectively inhibit the activity of alpha-glucosidase, and animal experiments prove that the newly designed polypeptide has the effects of reducing blood sugar, reducing blood lipid, improving insulin resistance and the like through polypeptide intervention; compared with traditional hypoglycemic drugs, the alpha-glucosidase inhibiting peptide has significant safety.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biopharmaceuticals, and relates to an α-glucosidase inhibiting peptide and application thereof. BACKGROUND

[0002] Diabetes mellitus (DM) is a metabolic disease characterized by elevated blood glucose levels, which is influenced by a combination of environmental, genetic, and various other factors. According to the Global Diabetes Atlas released by the International Diabetes Federation in 2021, the number of patients with diabetes is expected to reach 693 million in 25 years. Among them, type 2 diabetes mellitus (T2DM) accounts for about 90% of all diabetes cases, and its pathogenesis is mainly caused by resistance of the body to the normal action of insulin. The elevated blood glucose level associated with diabetes often leads to complications, including cardiovascular and cerebrovascular diseases, peripheral neuropathy, liver function damage, etc., which poses a major threat to personal health.

[0003] In the treatment of T2DM, α-glucosidase is a commonly used target for diabetes treatment. It is a membrane-bound enzyme located on the surface membrane of the intestinal cell brush border, which promotes the release of glucose by breaking the bond between the non-reducing end glucose residue of oligosaccharides and the glucose residue oxygen. The mechanism of action of α-glucosidase inhibitors is to weaken the activity of α-glucosidase, thereby inhibiting the hydrolysis of disaccharides or oligosaccharides. This delays the absorption of carbohydrates by the body and can effectively slow down the postprandial hyperglycemia level. Nowadays, α-glucosidase inhibitors have become a first-line hypoglycemic drug for the effective treatment of type 2 diabetes. However, some α-glucosidase inhibitors such as acarbose and voglibose, although effective in lowering blood sugar, have significant gastrointestinal side effects and liver damage, which limits their long-term application by patients. Therefore, finding a safe and effective α-glucosidase inhibitor has become a research hotspot.

[0004] Existing α-glucosidase inhibitors (such as acarbose) have problems of gastrointestinal side effects and insufficient target selectivity, while traditional polypeptide drug design relies on empirical screening, which is low in efficiency and limited in accuracy of activity prediction. In addition, the single high-fat diet or STZ induction method in the construction of animal models of diabetes often leads to unstable phenotypes (such as large blood glucose fluctuations and insufficient β-cell damage), and existing research does not comprehensively evaluate the metabolic protection effects of polypeptides (such as liver and kidney function, lipid metabolism regulation).

[0005] In recent years, polypeptide drugs have become a research hotspot due to their high specificity, low toxicity and modifiability. Traditional polypeptide separation and purification methods such as ultrafiltration, macroporous resin adsorption, gel chromatography, reverse phase high performance liquid chromatography and ion exchange chromatography mainly screen polypeptides based on the size, charge polarity, solubility and other physical and chemical properties of peptide molecules, and the intermediate process is complex and time-consuming. With the development of science and technology, the development of new bioactive peptides through virtual screening combined with in vitro and in vivo experiments can reduce the cost of manpower, shorten the development cycle and improve the success rate of bioactive peptide identification. SUMMARY

[0006] In the present application, four polypeptides with high affinity to the active center of alpha-glucosidase are screened by computer simulation design combined with molecular docking technology, and the in vitro inhibitory activity of the polypeptides on alpha-glucosidase is verified, and an active polypeptide with high potential for hypoglycemic effect is screened through a hyperglycemic animal model.

[0007] The first aspect of the present application provides a polypeptide molecule, characterized in that the polypeptide molecule can inhibit the activity of alpha-glucosidase, the polypeptide molecule comprises FPKIPPP, 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 FPKIPPP.

[0008] The second aspect of the present application provides an alpha-glucosidase inhibitor, characterized in that the inhibitor comprises the polypeptide molecule of the first aspect.

[0009] The third aspect of the present application provides a pharmaceutical composition for treating diabetes, characterized in that the pharmaceutical composition comprises the polypeptide molecule of the first aspect.

[0010] Further, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier, and the administration mode of the drug comprises oral administration, injection and gavage.

[0011] Further, the administration dose of the polypeptide molecule is 80-120 mg / kg of body weight.

[0012] The fourth aspect of the present application provides the use of the polypeptide molecule of the first aspect in the preparation of a drug for treating diabetes.

[0013] Further, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier, and the administration mode of the drug comprises oral administration, injection and gavage.

[0014] Further, the administration dose of the polypeptide molecule is 80-120 mg / kg of body weight.

[0015] The fifth aspect of the present application provides the polypeptide molecule of the first aspect for use in the preparation of a preparation for reducing blood lipid.

[0016] Further, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier, and the administration mode of the medicine comprises oral administration, injection and gavage.

[0017] Further, the administration dose of the polypeptide molecule is 80-120 mg / kg body weight.

[0018] The beneficial effects of the present application include:

[0019] 1. The unreported peptide segment FPKIPPP provided in the present application has the advantages of safety, non-toxicity and no side effects, can effectively inhibit the activity of alpha-glucosidase, regulate postprandial blood glucose, and thus has a certain relieving effect on diabetes and its complications.

[0020] 2. The alpha-glucosidase inhibiting peptide involved in the present application can be used as a core active ingredient, and by adding appropriate excipients, a series of functional products for regulating blood lipid and blood glucose can be prepared. These products can meet the diversified administration needs and are suitable for type 2 diabetes patient groups. Compared with traditional hypoglycemic drugs, the alpha-glucosidase inhibiting peptide of the present application has significant safety and no adverse reactions.

[0021] 3. Based on the diabetes mouse model induced by high-fat diet (HFD) and streptozotocin (STZ) combination, the polypeptide intervention proves that the newly designed polypeptide has the effects of reducing blood glucose, reducing blood lipid, improving insulin resistance, etc. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a molecular docking simulation diagram of the polypeptide: A: A1; B: A2; C: A3; D: A4;

[0023] Figure 2 Mass spectrum and chromatogram of polypeptide synthesis;

[0024] Figure 3 In vitro activity determination of polypeptide and animal experiment intervention: A, in vitro enzyme activity of polypeptide; B, body weight; C, fasting blood glucose; D, total cholesterol; E, triglyceride; F, serum glutathione transaminase level; G, serum glutathione transaminase level; H, serum high-density lipoprotein level; I, low-density lipoprotein level; J, insulin tolerance ITT; K, glucose tolerance OGTT; L, ITT AUC; M, OGTT AUC; N, food intake; O, water intake; P, pancreatic and liver tissue pathological staining results. DETAILED DESCRIPTION

[0025] The concept and the technical effects of the present application are further described below in connection with specific embodiments, so as to fully understand the objects, features and effects of the present application. The methods are all conventional methods unless otherwise specified. The materials can be obtained from public commercial channels unless otherwise specified. The illustrative embodiments of the present application and the descriptions thereof are used to explain the present application and do not constitute an improper limitation of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0026] Design and activity site analysis of peptides in Example 1

[0027] 1) The present application screens 4 polypeptides with α-glucosidase inhibition potential from a polypeptide library through computer-aided drug design combined with molecular docking technology.

[0028] First, α-glucosidase is searched from the Protein Data Bank (PDB) to obtain the X-ray diffraction crystal structure of α-glucosidase. The structure is processed using Discoverystudio2.5 software, missing residues are completed, hydrogen bond network is optimized, and the protonation state of the key catalytic residues is distributed (ProtonateProtein tool) under the condition of pH 7.4, so as to obtain a complete molecular structure. At the same time, the conserved region is analyzed and an active conformation model is established to preliminarily judge the active domain. Subsequently, based on the pharmacophore characteristics (hydroxyl, aromatic ring and positive charge group) of the natural inhibitor, a virtual library containing 500 polypeptides is designed and generated using the Peptide Designer module, and conformation sampling (10 low-energy conformations are retained) is performed through the Conformation Generation tool. AutoDock is used for molecular docking: after the polypeptide conformation is pretreated by Prepare Ligands, the flexible side chains of Asp214 and Glu277 are defined as the active pocket (grid range ), Lamarckian genetic algorithm (50 runs, population size 150) is set to complete high-precision docking, and the binding free energy (ΔG<-7.0 kcal / mol) and RMSD clustering analysis Top 4 candidate polypeptides are screened; hydrogen bonds and hydrophobic interactions are analyzed by Pose Analysis to exclude steric conflict sequences. In addition, the biological activity of the polypeptides is predicted by the Peptide Ranker database (a score of >0.5 is the activity threshold), and the toxicity is evaluated by the ToxinPred online tool. Finally, the docking results are visualized by the Visualization Tools of Discovery Studio to verify the stability of the hydrogen bond network and the binding mode.

[0029] As shown in Table 1, the sequences of polypeptides A1, A2, A3 and A4 are WFQHW, MPGPPYD, QFPRW and FPKIPPP respectively, and based on molecular docking analysis, the docking affinity (binding energy) of polypeptides A1, A2, A3 and A4 with the α-glucosidase protein crystal is -11.4, -10.7, -10 and -9.4 kcal / moL respectively, indicating that they have good binding affinity with α-glucosidase and have stable binding capacity.

[0030] 2) Analyze the binding site and interaction between the active peptide and α-glucosidase, use Peptide Ranker database to predict the biological activity of polypeptide (score > 0.5 as the activity threshold), and at the same time evaluate the toxicity by ToxinPred online tool. Finally, the docking results can be visualized by Discovery Studio's Visualization Tools to verify the stability of hydrogen bond network and binding mode.

[0031] As shown in Figure 1, in the polypeptide A1 docking box, polypeptide A1 forms traditional hydrogen bonds with amino acid residues ASN447, GLN439, HIS515, ASN443 and ASN46 of α-glucosidase, forms carbon-hydrogen bonds with ASP440 and GLN439, and forms Π-alkyl bonds with ALA451 and LYS352; in the polypeptide A2 docking box, polypeptide A2 forms traditional hydrogen bonds with amino acid residues ASN443 and GLN531 of α-glucosidase, forms carbon-hydrogen bonds with ALA529, ASP40 and SEP44, and forms Π-alkyl bonds with TYR41 and ALA514; in the polypeptide A3 docking box, polypeptide A3 forms traditional hydrogen bonds with amino acid residues ASP40, THR517, THR519, ASN443, ASN447 and GLN439 of α-glucosidase, forms carbon-hydrogen bonds with LYS352, and forms Π-alkyl bonds with PRO528; in the polypeptide A4 docking box, polypeptide A4 forms traditional hydrogen bonds with amino acid residues THR517, SER44, ASN447 and GLN439 of α-glucosidase, forms carbon-hydrogen bonds with ARG450 and ASN447, and forms Π-alkyl bonds with LYS352, ALA444 and PRO442.

[0032] In addition, as shown in Table 1, according to bioinformatics prediction, the biological activities of polypeptides A1, A2, A3 and A4 are 0.982583, 0.721492, 0.975774 and 0.90982 respectively, and the toxicity of them is predicted by ToxinPred online tool, and the prediction result shows that they are all non-toxic, indicating that the four polypeptides screened have application potential and certain biological safety.

[0033] Table 1 Binding energy, biological activity and toxicity of polypeptides

[0034]

[0035]

[0036] Example 2 Synthesis, purity and in vitro activity detection of polypeptides

[0037] The polypeptides A1, A2, A3 and A4 screened in the previous stage were synthesized by solid phase synthesis.

[0038] 1. Polypeptide synthesis: The polypeptide sequence was synthesized by solid phase synthesis in the order of C-terminal to N-terminal by using in vitro Fmoc solid phase method. The dried crude peptide was prepared by amino acid connection reaction, peptide chain connection reaction and peptide chain cleavage treatment. The crude peptide obtained by chemical synthesis was purified and detected by using high performance liquid chromatograph and high resolution mass spectrometer (purification condition: mobile phase A was 0.065% (V / V) trifluoroacetic acid aqueous solution in pure water, mobile phase B was 0.05% (v / v) trifluoroacetic acid solution in acetonitrile, total flow rate: 1 ml / min, detection wavelength: 220 nm). The peptide synthesis was completed by Kings River Co., Ltd.

[0039] As shown in Table 2, the actual molecular weights of the synthesized polypeptides A1, A2, A3 and A4 were 802.4, 775.4, 732.8 and 795.00 respectively, which were consistent with the theoretical molecular weights.

[0040] In addition, as shown in the chromatogram of Table 2, the synthesized polypeptide components were uniform and had high purity, and there were only single chromatographic peaks. As shown in Table 2, the purities of the synthesized polypeptides A1, A2, A3 and A4 were 97.242%, 98.957%, 96.963% and 96.295% respectively, which could be used for in vitro and in vivo experiments. Figure 2

[0041] ​2. Glucosidase activity inhibition experiment: A polypeptide aqueous solution with a concentration of 4 mg / mL was prepared using distilled water, 10 μL of the polypeptide solution and 10 μL of α-glucosidase solution (0.3 U, prepared using 0.1 mol / L, pH = 7.2 phosphate buffer) were added to an enzyme-labeled plate, mixed, and incubated at 37°C for 10 min. Then, 120 μL of 2.5 mmol / L PNPG (p-nitrophenyl-α-D-glucopyranoside) solution was added, incubated at 37°C for 15 min, and then 50 μL of 0.2 mol / L Na2CO3 solution was added to terminate the reaction, and the absorbance at 405 nm (denoted as A sample) was measured. The buffer was used instead of the sample as a blank group. Meanwhile, an acarbose aqueous solution with a concentration of 4 mg / mL was used as a positive control. The α-glucosidase inhibition activity calculation formula is: α-glucosidase activity inhibition rate (%) = [(A blank - A sample) / A blank] x 100.

[0042] The in vitro activity determination results are shown in Table A, with acarbose as a positive control, the enzyme inhibition activity of polypeptides A1, A2, A3, A4 and A5 on α-glucosidase was 98.68%, 91.3%, 1.98%, 2.18% and 98.32%, respectively. Among them, the enzyme inhibition activity of polypeptide A1 and polypeptide A4 was significantly higher than that of polypeptide A2 and polypeptide A3, and the enzyme inhibition activity of polypeptide A4 on α-glucosidase was not significantly different from that of acarbose, indicating that polypeptide A4 has similar enzyme activity inhibition effect as acarbose. Figure 3

[0043] Table 2. Synthesis of polypeptides

[0044] Polypeptide name Theoretical molecular weight Actual molecular weight Purity A1 802.89 802.4 97.242％ A2 775.88 775.4 98.957％ A3 732.84 732.8 96.963％ A4 795.00 795.00 96.295％

[0045] Example 3. Animal experiment

[0046] A type 2 diabetes mouse model was constructed, polypeptide A1 and polypeptide A4 were selected for intervention, and the alleviating effect of the active polypeptides on the diabetic mice was evaluated from six aspects of body weight, fasting blood glucose level, food intake, water intake, serum indicators (total cholesterol, triglyceride, glutamic-pyruvic transaminase, glutamic-oxalacetic transaminase, high-density lipoprotein and low-density lipoprotein), pathological degree of liver and pancreas, and insulin tolerance and glucose tolerance.

[0047] ​1. Mouse model construction: 6-week-old C57BL / 6J mice were purchased and acclimated for 7 days under laboratory conditions (22 ± 2℃, 50 ± 5%, 12 h light / dark cycle). After 7 days, the mice were divided into two groups, one group was fed with regular chow and served as the control group (NC), and the other group was fed with high-fat chow to induce T2DM model and served as the test group. After 6 weeks of high-fat diet, the test group mice were fasted for 12 h without water, and then injected with streptozotocin (STZ, 70 mg / kg bw) intraperitoneally three times, and the control group was injected with the same volume of citrate buffer. After 3 days of STZ injection, the mice were fasted for 12 h without water, and then the tail tip blood glucose value was measured. Mice with fasting blood glucose (FBG) ≥ 11.1 mmol / L were selected for further feeding for 1 week, and the rest of the mice with blood glucose values that did not meet the standard were injected with STZ (70 mg / kg·bw) intraperitoneally again. When the FBG of the mice was ≥ 11.1 mmol / L, they were considered as T2DM model mice. The T2DM model mice were fed with high-fat chow throughout the experimental period.

[0048] 2. Group administration: According to the random grouping method, the test group mice that had become T2DM models were divided into 4 groups according to blood glucose values, namely the diabetes group, the polypeptide intervention group A1, the polypeptide intervention group A4, and the acarbose group (positive control). At the same time, mice fed with regular chow were used as blank controls.

[0049] 1) Blank control group: equal amount of normal saline was administered intragastrically daily;

[0050] 2) Diabetes group: equal amount of normal saline was administered intragastrically daily;

[0051] 3) Active peptide intervention group A1: polypeptide A1 was administered intragastrically at a dose of 100 mg / kg·bw;

[0052] 4) Active peptide intervention group A4: polypeptide A4 was administered intragastrically at a dose of 100 mg / kg·bw;

[0053] 5) Acarbose group: acarbose was administered intragastrically at a dose of 100 mg / kg·bw.

[0054] During feeding, mice were allowed to eat and drink freely, and body weight and fasting blood glucose (FBG) were recorded every 7 days. The mice were fasted for 12 h without water before the determination of body weight and FBG. On the 28th day of the experiment, the mice were fasted for 12 h without water, and blood was collected from the eyeball into a blood collection tube in an ice bath. The blood was placed in an ice bath for half an hour, then centrifuged at 4℃ (1000g / min, 10 min), and the upper serum was aliquoted and stored at -80℃ for future use. After blood collection, the mice were sacrificed by cervical dislocation, dissected, and the liver, kidney, pancreas, and other tissues were quickly stripped and frozen in liquid nitrogen for storage at -80℃. Another part was stored in 4% paraformaldehyde for histological analysis.

[0055] 3. Test method

[0056] 3.1 Fasting blood glucose measurement

[0057] Before the experiment, the mice were fasted for 6 hours (free water), and the blood glucose value was measured by the tail tip blood sampling method using a portable blood glucose meter. Before blood collection, the tail tip was wiped to avoid contamination, and the tail was gently pressed to promote blood flow. A small amount of whole blood (about 1 μL) was dropped into the test paper detection area, and the stable reading (unit: mg / dL) was recorded. Each group was measured 3 times to take the average value, and the standard calibration instrument was set synchronously to ensure data reliability.

[0058] 3.2 Glucose tolerance measurement

[0059] Before the experiment, the mice were fasted for 6 hours (free water), and a 20% glucose solution was administered intragastrically at a dose of 2 g / kg body weight. The blood glucose value was measured by the tail tip blood sampling method before administration (0 min) and 15, 30, 60, 90, and 120 min after administration. The data were recorded using a blood glucose meter (calibrated daily), and the area under the curve (AUC) was calculated to evaluate glucose tolerance.

[0060] 3.3 Insulin tolerance measurement

[0061] Before the experiment, the mice were fasted for 4 hours (free water), and human regular insulin (0.75 U / kg body weight) was injected intraperitoneally. The blood glucose value was measured by the tail tip blood sampling method before injection (0 min) and 15, 30, 60, 90, and 120 min after injection. The data were recorded using a calibrated blood glucose meter, and the area under the curve (AUC) was calculated to evaluate insulin sensitivity.

[0062] 3.4 HE staining of tissues

[0063] Fresh liver and pancreas tissues were fixed in 4% tissue fixative overnight, dehydrated with ethanol (50%, 75%, and 95%) gradient, and paraffin-embedded. After the tissue section was deparaffinized and hydrated, it was stained with hematoxylin and eosin (H&E). An optical microscope was used to capture images and perform morphological examination.

[0064] 3.5 Measurement of liver function indicators

[0065] The blood samples of the mice were collected into an anticoagulant tube, and the tube was placed at 4°C for 4 h. The tube was centrifuged at 1000 g for 15 min at 4°C, and the supernatant serum was aliquoted and stored at -20°C. The liver tissue was accurately weighed (50 mg) in 500 μL PBS, and a 10% tissue homogenate (w / v) was prepared under ice water bath conditions. The mixture was centrifuged at 2500 rpm for 10 min at 4°C, and the supernatant was aliquoted and stored at -20°C for further analysis. Commercially available kits were used to measure the activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT).

[0066] 3.6 Serum index determination

[0067] The corresponding contents in serum were detected using a triglyceride assay kit, a total cholesterol assay kit, a high-density lipoprotein assay kit, and a low-density lipoprotein assay kit.

[0068] 4. Results:

[0069] As shown in Figure 3 B, the body weight of the diabetic mice was significantly lower than that of the control group, and acarbose, polypeptide A1, and polypeptide A4 could significantly restore the body weight of the diabetic mice, and the restoration level of polypeptide A4 was significantly higher than that of polypeptide A1, and there was no significant difference between the improvement effect of polypeptide A4 and that of acarbose, indicating that the improvement effect of polypeptide A4 on the body weight of the diabetic mice was similar to that of acarbose;

[0070] As shown in Figure 3 C, the fasting blood glucose level of the diabetic mice was significantly higher than that of the normal control group, polypeptide A1 could reduce the fasting blood glucose level of the diabetic mice to a certain extent, and polypeptide A4 and acarbose could significantly reduce the fasting blood glucose of the diabetic mice, and the improvement effect of polypeptide A4 was significantly better than that of acarbose and polypeptide A1;

[0071] As shown in Figure 3 N and Figure 3 O, compared with the normal control group, the diabetic mice showed polydipsia and polyphagia, and acarbose, polypeptide A1, and polypeptide A4 could alleviate this phenomenon to a certain extent, and the improvement effect of polypeptide A4 was significantly better than that of acarbose and polypeptide A1;

[0072] As shown in Figure 3 D, the serum total cholesterol level of the diabetic mice was significantly higher than that of the control, and acarbose, polypeptide A1, and polypeptide A4 could significantly reduce the serum total cholesterol level, and the improvement effect of polypeptide A4 was significantly better than that of polypeptide A1 and acarbose;

[0073] As shown in Figure 3 E, the serum triglyceride level of the diabetic mice was higher than that of the normal control group, and acarbose, polypeptide A1, and polypeptide A4 could significantly reduce the serum triglyceride level of the diabetic mice, and the improvement effect of polypeptide A4 was better than that of the acarbose group;

[0074] As shown in Figure 3 F, the serum glutamic-pyruvic transaminase level of the diabetic group was higher than that of the normal control group, and the acarbose group, the polypeptide A1 group, and the polypeptide A4 group could significantly reduce the serum glutamic-pyruvic transaminase level, and the effect of polypeptide A4 was significantly better than that of polypeptide A1 and acarbose;

[0075] As shown in Figure 3As shown in G, the serum glutamic-oxalacetic transaminase level of the diabetic group mice is significantly higher than that of the control group, and the acarbose group, the polypeptide A1 group and the polypeptide A4 group can significantly reduce the serum glutamic-oxalacetic transaminase level, wherein the improvement effect of the polypeptide A4 is significantly better than that of the polypeptide A1, and is better than that of the acarbose to a certain extent;

[0076] As shown in Figure 3 As shown in H, the serum high-density lipoprotein level of the diabetic group mice is significantly lower than that of the normal control group, and the acarbose, the polypeptide A1 and the polypeptide A4 can significantly restore the serum high-density lipoprotein level, wherein the improvement effect of the polypeptide A4 is significantly higher than that of the polypeptide A1 and the acarbose;

[0077] As shown in Figure 3 As shown in I, the low-density lipoprotein level of the diabetic group mice is significantly higher than that of the normal control group, and the acarbose, the polypeptide A1 and the polypeptide A4 can significantly reduce the low-density lipoprotein level in the serum, and the improvement effect of the polypeptide A4 is better than that of the polypeptide A1 and the acarbose;

[0078] As shown in Figure 3 As shown in J and Figure 3 As shown in L, the insulin tolerance of the diabetic mice is severely impaired, and the acarbose group and the polypeptide A4 can improve the insulin tolerance of the diabetic mice, wherein the improvement effect of the polypeptide A4 is significantly better than that of the polypeptide A1, and is better than that of the acarbose to a certain extent;

[0079] As shown in Figure 3 As shown in K and 3M, the glucose tolerance of the diabetic mice is severely impaired, and the acarbose and the polypeptide A4 can significantly improve the glucose tolerance of the diabetic mice, wherein the improvement effect of the polypeptide A1 is better than that of the polypeptide A1, and is better than that of the acarbose group to a certain extent;

[0080] As shown in Figure 3 As shown in P, the islets of the pancreatic tissue of the diabetic group appear serious atrophy and degeneration compared with the normal group, the area is small, the shape is irregular, the boundary is not clear, the number of insulin cells is small, the peripheral β cells are irregularly distributed and loosely arranged, and after the intervention of the active polypeptide, the damage of the pancreatic tissue is relieved to different degrees. The recovery degree of the pancreatic tissue of the polypeptide A4 and the acarbose group is close to that of the normal group, the islet area and the number of islet cells are significantly increased, the structure is complete and the boundary is clear;

[0081] As shown in Figure 3As shown in FIG. 6, the hepatocytes of the normal control group mice were normal in shape and uniform in size, and the liver tissue structure was complete. The hepatocytes of the diabetic mice were swollen, became hypertrophic, and the structure was disordered. The nucleus was not obvious and a large number of vacuoles of different sizes were visible around the nucleus. The improvement effect of polypeptide A1 was not obvious. The polypeptide A4 and acarbose intervention both significantly reduced the vacuoles around the nucleus, and the hepatocyte structure tended to be normal. The improvement effect of polypeptide A4 on the liver of diabetic mice was significantly better than that of polypeptide A1. In summary, polypeptide A4 can significantly alleviate the symptoms of diabetes by improving the body weight, food intake, and water intake of mice.

[0082] The above-described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

Claims

1. A polypeptide molecule, characterized in that, The polypeptide molecule described herein can inhibit α-glucosidase activity, and the polypeptide molecule is FPKIPPP.

2. An α-glucosidase inhibitor, characterized in that, The inhibitor comprises the polypeptide molecule of claim 1.

3. The inhibitor according to claim 2, characterized in that, The inhibitors also include pharmaceutically acceptable carriers.

4. A pharmaceutical composition for treating diabetes, characterized in that, The pharmaceutical composition contains the polypeptide molecule of claim 1.

5. The pharmaceutical composition according to claim 4, characterized in that, The pharmaceutical composition further includes a pharmaceutically acceptable carrier, and the administration route of the drug includes oral, injection, or gavage.

6. The pharmaceutical composition according to claim 4 or 5, characterized in that, The dosage of the polypeptide molecule is 80-120 mg / kg body weight.

7. The use of the polypeptide molecule according to claim 1 in the preparation of a medicament for treating diabetes, characterized in that, The dosage of the polypeptide molecule is 80-120 mg / kg body weight.

8. The application according to claim 7, characterized in that, The drug also includes a pharmaceutically acceptable carrier, and the drug is administered orally, by injection, or by gavage.

9. The use of the polypeptide molecule according to claim 1 in the preparation of a medicament for treating hyperlipidemia, characterized in that, The dosage of the polypeptide molecule is 80-120 mg / kg body weight.

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