Camel milk hypoglycemic peptide with DPP-IV inhibitory activity and GPR-40 agonist activity and its application

Abstract

The present invention belongs to the technical field of dairy products, and particularly relates to the preparation and application of camel milk hypoglycemic peptides with DPP-IV inhibitory activity and GPR-40 agonist activity. A method for preparing hypoglycemic peptides from camel milk is provided. By using the method of molecular docking, endogenous camel milk peptide sequences with the ability to inhibit DPP-IV and activate GPR-40 are screened, including AGM and KPAF. It is confirmed in vitro in HepG2 hepatocytes that the endogenous camel milk peptides can improve the uptake of insulin resistance and utilize glucose to synthesize glycogen; at the in vivo level, it is confirmed that the endogenous camel milk peptides have a certain improvement effect on insulin-resistant mice, and at the same time have the effects of inhibiting serum DPP-IV and activating the expression of colon GPR-40. Therefore, the endogenous camel milk peptides of the present invention have hypoglycemic activity, can relieve insulin resistance diseases, and provide a scientific basis for the development of health foods, drugs with blood sugar-regulating effects and industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of dairy products, and particularly relates to the preparation and application of a camel milk hypoglycemic peptide with DPP-IV inhibitory activity and GPR-40 agonist activity. Background Art

[0002] Insulin resistance is a common feature of a series of metabolic diseases, such as metabolic disorder obesity, type 2 diabetes, hypertension, and non-alcoholic fatty liver disease. Insulin resistance (IR) refers to the weakening of the efficacy of insulin in the body, and the reactivity (maximum effect of insulin) or sensitivity (insulin concentration required for half-maximal response) of tissues to the metabolic action of normal levels of insulin decreases. This leads to a decrease in the glucose uptake ability of the main tissues where insulin acts (liver, muscle, and adipose tissue), and the process of gluconeogenesis is activated.

[0003] Dipeptidyl peptidase-4 (DPP-IV) is a ubiquitously expressed 110 kDa serine protease. DPP-IV can inactivate a variety of bioactive peptides, including glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). DPP-IV inhibitors play their blood glucose control function by inactivating DPP-IV and increasing the expression levels of GLP-1 and GIP.

[0004] G protein-coupled receptor-40 (GPR-40, free fatty acid receptor) is a GPCRs that binds free fatty acids as ligands, exists in gastrointestinal enteroendocrine cells, immune cells, and some cells in the brain, is highly expressed in pancreatic β cells, and responds to endogenous fatty acids when blood glucose levels increase, resulting in an amplified insulin secretion. GPR-40 is related to the role of free fatty acids in acutely stimulating insulin and incretin secretion. GPR-40 agonists can be attractive target drugs for mediating insulin secretion and are used to treat type 2 diabetes. GPR-40 partial agonists can reduce glucose by enhancing glucose-stimulated insulin secretion, can significantly reduce glucose, and do not cause weight gain or hypoglycemia risks associated with exogenous insulin or glucose-independent insulin secretagogues.

[0005] The present invention utilizes the DPP-IV inhibitory activity and GPR-40 agonist activity of camel milk endogenous peptides to improve insulin resistance and fat accumulation induced by a high-fat diet and reduce body weight. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention aims to provide a method for improving insulin resistance. By preparing endogenous peptides from camel milk, polypeptides with DPP-IV inhibitory activity and GPR-40 agonist activity are obtained, solving the problems caused by insulin resistance.

[0007] To achieve the above object, on the one hand, the present invention provides 2 camel milk endogenous hypoglycemic peptides with hypoglycemic effects, and their amino acid sequences are: AGM (SEQ ID NO.1) and KPAF (SEQ ID NO.2).

[0008] On the second aspect, the present invention provides a method for preparing camel milk endogenous hypoglycemic peptides, which is prepared by the following method:

[0009] (1) Raw camel milk is centrifuged at 4000 g and 4 °C for 20 min, and the middle sample is taken to obtain defatted camel milk;

[0010] (2) The pH of defatted camel milk is adjusted to 4.6 with 1 M HCl, left standing at 4 °C for 10 min, and then centrifuged at 4000 g for 10 min, and the supernatant is collected to obtain camel milk whey;

[0011] (3) The camel milk whey is ultrafiltered and centrifuged to obtain endogenous peptides for freeze-drying and storage;

[0012] (4) The above-mentioned camel milk endogenous peptides are subjected to peptide sequence analysis to obtain the polypeptide sequences in the endogenous peptides.

[0013] On the third aspect, the present invention provides a composition, which contains at least one or both of AGM (SEQ ID NO.1) and KPAF (SEQ ID NO.2).

[0014] On the fourth aspect, the present invention also provides the application of camel milk endogenous hypoglycemic peptides in insulin resistance. Specifically, it is the application of camel milk endogenous hypoglycemic peptides in the preparation of health foods that help control body fat, help maintain a healthy blood lipid level, help maintain a healthy blood glucose level, and help maintain a healthy blood pressure level.

[0015] Specifically, it is the application of camel milk endogenous hypoglycemic peptides in the preparation of products for preventing and / or treating diabetes, obesity, insulin resistance, and non-alcoholic fatty liver disease.

[0016] Specifically, it is the application of camel milk endogenous hypoglycemic peptide composition in products for improving insulin resistance.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention provides a method for efficiently utilizing camel milk whey, providing a basis for the comprehensive utilization of camel milk whey, and having high social significance and economic value.

[0019] (2) Based on the identification of the amino acid sequences of endogenous peptides in camel milk, the present invention uses the method of molecular docking to screen and obtain a total of four endogenous peptide sequences of camel milk that have the ability to inhibit DPP-IV and activate the intestinal GPR-40 receptor, namely AGM (SEQ ID NO.1), KPAF (SEQ ID NO.2), FPQPQ (SEQ ID NO.3), and GPGGAW (SEQ ID NO.4), which greatly reduces the workload of experimental verification and improves the accuracy of specific function screening.

[0020] (3) The present invention proposes that the amino acid sequences of AGM and KPAF have an effective improvement effect on insulin-resistant HepG2 cells and promote glucose consumption and glycogen synthesis.

[0021] (4) The present invention proves that the amino acid sequences of AGM and KPAF have the ability to reduce the levels of serum insulin, blood glucose, and glycated hemoglobin in mice induced by a high-fat diet, improve the chronic inflammation level of mice, reduce the total triglyceride and total cholesterol contents in the serum and liver of mice, and improve the liver damage of mice. Description of the Drawings

[0022] Figure 1 Molecular docking diagram of peptide AGM and DPP-IV.

[0023] Figure 2 Molecular docking diagram of peptide KPAF and DPP-IV.

[0024] Figure 3 Molecular docking diagram of peptide FPQPQ and DPP-IV.

[0025] Figure 4 Molecular docking diagram of peptide GPGGAW and DPP-IV.

[0026] Figure 5 Molecular docking diagram of peptide AGM and GPR-40.

[0027] Figure 6 Molecular docking diagram of peptide KPAF and GPR-40.

[0028] Figure 7 Molecular docking diagram of peptide FPQPQ and GPR-40.

[0029] Figure 8 Molecular docking diagram of peptide GPGGAW and GPR-40.

[0030] Figure 9 Effect of endogenous peptides in camel milk on glucose consumption of insulin-resistant HepG2 cells (different lowercase letters indicate significant differences between groups,p <0.05).

[0031] Figure 10 Effect of endogenous peptides from camel milk on glycogen synthesis in insulin-resistant HepG2 cells (different lowercase letters indicate significant differences between groups, p <0.05).

[0032] Figure 11 Changes in body weight of insulin-resistant mice during the intervention with endogenous peptides from camel milk.

[0033] Figure 12 Changes in food intake of insulin-resistant mice during the intervention with endogenous peptides from camel milk.

[0034] Figure 13 Effect of endogenous peptides from camel milk on oral glucose tolerance (OGTT) in insulin-resistant mice.

[0035] Figure 14 Quantification graph of the area under the OGTT curve (AUC) in insulin-resistant mice treated with endogenous peptides from camel milk (different lowercase letters indicate significant differences between groups, p <0.05).

[0036] Figure 15 Effect of endogenous peptides from camel milk on intraperitoneal insulin tolerance (IPITT) in insulin-resistant mice.

[0037] Figure 16 Quantification graph of the area under the IPITT curve (AUC) in insulin-resistant mice treated with endogenous peptides from camel milk (different lowercase letters indicate significant differences between groups, p <0.05).

[0038] Figure 17 Fasting insulin levels in insulin-resistant mice after intervention with endogenous peptides from camel milk (different lowercase letters indicate significant differences between groups, p <0.05).

[0039] Figure 18 Fasting blood glucose in insulin-resistant mice after intervention with endogenous peptides from camel milk (different lowercase letters indicate significant differences between groups, p <0.05).

[0040] Figure 19 Fasting glycated hemoglobin levels in insulin-resistant mice after intervention with endogenous peptides from camel milk (different lowercase letters indicate significant differences between groups, p <0.05).

[0041] Figure 20 Liver pathological tissue sections of insulin-resistant mice after intervention with endogenous peptides from camel milk.

[0042] Figure 21 The serum total triglyceride (TG) level after camel milk endogenous peptides intervened in insulin-resistant mice (different lowercase letters indicate significant differences between groups, p <0.05).

[0043] Figure 22 The serum total cholesterol (TC) level after camel milk endogenous peptides intervened in insulin-resistant mice (different lowercase letters indicate significant differences between groups, p <0.05).

[0044] Figure 23 The serum low-density lipoprotein (LDL-C) level after camel milk endogenous peptides intervened in insulin-resistant mice (different lowercase letters indicate significant differences between groups, p <0.05).

[0045] Figure 24 The liver total triglyceride (TG) level after camel milk endogenous peptides intervened in insulin-resistant mice (different lowercase letters indicate significant differences between groups, p <0.05).

[0046] Figure 25 The liver total cholesterol (TC) level after camel milk endogenous peptides intervened in insulin-resistant mice (different lowercase letters indicate significant differences between groups, p <0.05).

[0047] Figure 26 The serum DPP-IV level after camel milk endogenous peptides intervened in insulin-resistant mice (different lowercase letters indicate significant differences between groups, p <0.05).

[0048] Figure 27 The colon GPR-40 mRNA level after camel milk endogenous peptides intervened in insulin-resistant mice (different lowercase letters indicate significant differences between groups, p <0.05). Detailed implementation manners

[0049] The following further elaborates on the concept and technical effects of 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.

[0050] Example 1: Preparation of Endogenous Peptides from Camel Milk with Improved Insulin Resistance and Hypoglycemic Effects

[0051] In this example, endogenous peptides from camel milk with improved insulin resistance and hypoglycemic activity were prepared by the following method:

[0052] (1) Raw camel milk was centrifuged at 4000 g for 20 min at 4°C, and the middle sample was taken to obtain defatted camel milk;

[0053] (2) The pH of the defatted camel milk was adjusted to 4.6 with 1 M HCl, allowed to stand at 4°C for 10 min, and then centrifuged at 4000 g for 10 min. The supernatant was collected to obtain camel milk whey;

[0054] (3) The camel milk whey was ultrafiltered and centrifuged to obtain endogenous peptides, which were stored by lyophilization;

[0055] (4) The above endogenous peptides from camel milk were subjected to peptide sequence analysis to obtain the polypeptide sequences in the endogenous peptides from camel milk.

[0056] Example 2: Identification of Amino Acid Sequences of Endogenous Peptides from Camel Milk

[0057] (1) Desalting: Further desalting was performed using a C18 column. The C18 column was activated with 1.5 mL of methanol and then equilibrated with 1.5 mL of 0.1% (V / V) TFA-H 2 2O solution. The endogenous peptides from camel milk were redissolved in 0.1% (V / V) TFA-H 2 2O solution and then added to the C18 column. Elution was carried out with 1.5 mL of 80% (V / V) ACN / 0.1% (V / V) TFA-H 2 2O solution. The eluate was collected and its peptide concentration was measured for TripleTOF™ 6600+ MS analysis.

[0058] (2)Peptide sequence identification: The peptide sequence was identified by liquid chromatography - electrospray ionization tandem mass spectrometry (LC-ESI MS / MS). Camel milk was dissolved in 0.1% formic acid solution and analyzed by an Orbitrap Q-Exactive Plus mass spectrometer. The samples were separated with a 60-min gradient. The column flow rate was 300 nL / min, the column temperature was 40 °C, and the electrospray voltage was 2 kV. The chromatographic gradient was as follows (A: 0.1% aqueous formic acid solution; B: 0.1% formic acid acetonitrile solution): The gradient started from 2% of phase B, increased non-linearly to 35% in 47 min, increased to 100% in 1 min, and was maintained for 12 min. The mass spectrometry parameters were set as follows: (1) MS: scan range (m / z) = 200–2000; resolution = 70000; AGC target = 3e6; maximum injection time = 50 ms; (2) HCD-MS / MS: resolution = 17500; AGC target = 1e5; maximum injection time = 45 ms; collision energy: 28%; dynamic exclusion time: 30 s.

[0059] (3)The obtained peptide data was compared with the UniProt and NCBI databases to identify the amino acid sequences of endogenous peptides in camel milk.

[0060] Example 3: Screening of potential DPP-IV inhibitory peptides and GPR-40 agonist synthetic peptides

[0061] PeptideRanker was used to evaluate the potential biological activities of the peptides. The values of this program range from 0 to 1, and the threshold is 0.8. Considering the peptide-protein binding energy, homology, and appropriate length of the peptides, the top high-affinity peptides were retained. Table 1 shows the peptide sequences with a DPP-IV docking score higher than 0.8. Table 2 shows the peptide sequences with a GPR-40 docking score higher than 0.8.

[0062] According to the docking energy of endogenous peptides in camel milk with key proteins of insulin resistance, four polypeptides were screened from the identified peptides, namely AGM (SEQ ID NO.1), KPAF (SEQ ID NO.2), FPQPQ (SEQ ID NO.3), and GPGGAW (SEQ ID NO.4). These four peptides can dock with both DPP-IV and GPR-40 simultaneously, and the peptide scores are higher than 0.8. Among them, the docking energies of AGM and KPAF with DPP-IV and GPR-40 are both higher than those of FPQPQ and GPGGAW. Figure 1-4 Figure for the molecular docking of the four peptides with DPP-IV Figure 5-8 Figure for the molecular docking of the four peptides with GPR-40

[0063] The bioactive peptides provided by the present invention are derived from endogenous peptides of camel milk and can also be obtained by solid-phase synthesis. The peptide segments AGM (SEQ ID NO.1), KPAF (SEQ ID NO.2), FPQPQ (SEQ ID NO.3), and GPGGAW (SEQ ID NO.4) used in the following examples were obtained by solid-phase synthesis. Shanghai Nuoyou Biotechnology Co., Ltd. was commissioned to perform solid-phase synthesis of the above hypoglycemic peptide segments for subsequent experiments.

[0064] Table 1 Docking energy of camel milk bioactive peptides with DPP-IV protein

[0065]

[0066] Table 2 Docking energy of camel milk bioactive peptides with GPR-40 protein

[0067]

[0068] Example 4: Determination of in vitro glucose absorption rate and glycogen synthesis rate of peptide segments

[0069] By constructing insulin-resistant HepG2 cells, the effects of peptide segments on glucose utilization and glycogen synthesis in insulin-resistant liver cells were evaluated. The specific steps are as follows:

[0070] Add 200 μL of cell suspension to each well of a 96-well plate and place it in an incubator at 37°C and 5% CO 2 for 24 h to establish an insulin resistance model. Add 10 μL of sample solution to the experimental group and 10 μL of PBS to the blank group. After 24 h, aspirate the culture medium in the 96-well plate for determination of glucose absorption rate. The glucose absorption rate was determined using a glucose oxidase detection kit (Nanjing Jiancheng Bioengineering Institute, A154-1-1).

[0071] Add 2 mL of cell suspension to each well of a 6-well plate and place it in an incubator at 37°C and 5% CO 2 for 24 h to establish an insulin resistance model. Add 100 μL of sample solution to the experimental group and 100 μL of PBS to the blank group. The glycogen content in the cells was determined using a glycogen kit (Nanjing Jiancheng Bioengineering Institute, A043-1-1).

[0072] Compared with the normal group, the glucose consumption in the model group decreased by 66.7%, and the intracellular glycogen content decreased by 38.63%, indicating that an insulin resistance model of HepG2 cells was successfully established. Camel milk endogenous peptides AGM, KPAF, FPQPQ, and GPGGAW, which can dock with both DPP-IV and GPR-40 simultaneously and have a score higher than 0.8 in molecular docking, were synthesized in vitro to verify their insulin resistance effects on HepG2.Figure 9 It can be seen that camel milk endogenous peptides can effectively improve insulin resistance in HepG2 cells. Among them, the intervention effects of AGM and KPAF are the best, increasing by 135.14% and 102.65% respectively compared with the model group. Figure 10 It can be seen that camel milk endogenous peptides can effectively improve the glycogen synthesis ability of HepG2 cells. Among them, the intervention effects of AGM and KPAF are the best, increasing by 46.51% and 43.90% respectively compared with the model group.

[0073] Example 5: Improvement effect of camel milk endogenous peptides on insulin resistance in high-fat diet mice

[0074] According to Examples 2, 3, and 4, the peptide segments AGM and KPAF have good hypoglycemic effects and can promote glucose uptake and storage in vitro. Animal experiments were conducted using camel milk endogenous peptides to study their hypoglycemic effects in vivo.

[0075] Male C57BL / 6J mice at 5 weeks of age (35 - 41 days) were selected and purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. License number: SCXK (Jing) 2021 - 0011, and the use license number: SYXK (Jing) 2020 - 0037. They were raised according to the SPF - level animal feeding standards. The animal experiment was reviewed and approved by the Animal Experiment Committee of China Agricultural University, and the ethical review number was KY160049. The laboratory environment was stable, with a temperature of 22 ± 1°C, a humidity of 40 ± 10%, a pressure difference of 20 - 50 Pa, and a 12 - hour light - dark cycle. After 1 week of adaptation, the mice were randomly divided into a normal diet (ND) group (n = 6) and a high - fat diet (HFD) group (n = 24). The mice in the ND group were fed a normal vitamin diet, and the mice in the HFD group were fed a high - fat diet for 10 weeks to construct a mouse model of insulin resistance induced by a high - fat diet. After 10 weeks, the fasting blood glucose, fasting insulin, and glycated hemoglobin levels were measured, and the insulin resistance index (HOMA - IR) was calculated. The insulin resistance index of the mice in the HFD group was greater than 2.69, indicating that the insulin resistance model induced by a high - fat diet was successfully constructed. The high - fat diet mice were randomly divided into an HFD group, an AGM group, a KPAF group, and a metformin group (HFDMet group), with 6 mice in each group. The corresponding intervention substances were given for nine weeks, and the food intake and body weight of the mice were measured weekly during the intervention period.

[0076] During the intervention period, the changes in the body weight of the mice were monitored to explore the improvement effect of the application examples of the present invention on obesity induced by a high - fat diet. As Figure 11As shown, compared with the ND group, the body weight of mice in the HFD group increased significantly, and the weight gain trend increased with the increase of intervention time. Intervention with AGM and KPAF groups could significantly reduce obesity induced by high-fat diet and reduce the body weight of mice. The food intake of mice was measured every three days, and the results were as Figure 12 shown, indicating that the improvement of insulin resistance caused by AGM and KPAF intervention was not due to the decrease in food intake.

[0077] After 8 weeks of intervention, the mice were fasted but given water for 12 h, and glucose was intragastrically administered to the mice at a dose of 2 g / kg BW. Tail tip blood was collected from the mice at 0, 30, 60, 90, and 120 min after intragastric administration, and the blood glucose value was measured with a blood glucose meter. A curve was drawn and the area under the curve (Area under cure, AUC) was calculated.

[0078] As Figure 13-14 shown, the blood glucose of the mice increased after intragastric administration of glucose and reached the maximum value at 30 min. The blood glucose level tended to be stable at 90 min after intragastric administration. Compared with the ND group, at 120 min after intragastric administration of glucose, the blood glucose of HFD mice was still at a relatively high level. The area under the curve (Area-under-the-curve, AUC) during the OGTT test was 1.68 times that of the ND group. This indicates that the glucose tolerance ability of mice induced by high-fat diet was impaired and the ability to regulate blood glucose decreased. Intervention with endogenous peptides from camel milk and metformin effectively improved the ability of insulin-resistant mice to regulate blood glucose and had a good effect on improving glucose tolerance damage induced by high-fat diet. The hypoglycemic peptide segments AGM and KPAF decreased the AUC of HFD mice by 15.04% and 16.24% respectively. Metformin intervention decreased the AUC of HFD mice by 14.68%. The above results indicate that endogenous peptides from camel milk can improve glucose tolerance impairment in insulin-resistant mice and enhance the blood glucose regulation ability of high-fat diet mice.

[0079] After 9 weeks of intervention, insulin (0.75 U / kg b.w.) was intraperitoneally injected. Tail tip blood was collected to measure the blood glucose level before insulin injection (0 min) and at 30 min, 60 min, 90 min, and 120 min after insulin injection. A curve was drawn and the area under the curve (Area under cure, AUC) was calculated.

[0080] As Figure 15-16As shown, after intraperitoneal injection of insulin, the blood glucose level of mice decreased rapidly. The blood glucose gradually rebounded 90 minutes after intraperitoneal injection. Compared with the ND group, the blood glucose of mice in the HFD group decreased more slowly after insulin injection, and the area under the curve (AUC) increased significantly, which was 1.61 times that of the ND group, indicating that high-sugar and high-fat diet-induced insulin sensitivity impairment in mice. Endogenous peptides in camel milk and metformin significantly increased the rate of blood glucose decline in insulin-resistant mice. Endogenous peptides AGM and KPAF in camel milk significantly improved the impaired insulin tolerance in insulin-resistant mice, reducing the AUC of insulin mice by 20.21% and 17.39% respectively. Metformin intervention reduced the AUC of HFD mice by 25.90%. It shows that endogenous peptides in camel milk effectively improved the insulin tolerance of HFD mice and alleviated the degree of insulin resistance in mice.

[0081] Fasting insulin, fasting blood glucose and glycated hemoglobin of mice were measured to explore the effects of the application examples of the present invention on the indicators in the serum of insulin-resistant mice induced by high-fat diet. The results are as Figure 17-19 shown. Compared with the ND group, the levels of fasting insulin, fasting blood glucose and glycated hemoglobin in HFD mice were significantly increased, indicating that high-fat diet induced diabetes and insulin resistance in mice. After intervention with hypoglycemic peptide segments AGM and KPAF, the fasting insulin levels of insulin-resistant mice were significantly decreased by 27.55% and 26.64% respectively; after intervention with hypoglycemic peptide segments AGM and KPAF, the fasting blood glucose levels of insulin-resistant mice were significantly decreased by 27.22% and 24.80% respectively, and there was no significant difference from the positive drug group of metformin after intervention; after intervention with hypoglycemic peptide segments AGM and KPAF, the fasting blood glucose levels of insulin-resistant mice were significantly decreased by 39.85% and 36.48% respectively.

[0082] Mouse liver tissues were taken for H&E staining to explore the effects of the application examples of the present invention on lipid accumulation and liver injury induced by high-fat diet. As Figure 20 shown, compared with the ND group, the lipid droplets in the liver tissues of HFD mice increased and balloon-like lesions were severe, indicating that high-fat diet induced lipid accumulation in mice. Intervention with hypoglycemic peptide segments AGM and KPAF significantly reduced the lipid droplet accumulation in liver cells and the degree of liver injury, indicating that endogenous peptides in camel milk have an improving effect on reducing lipid accumulation and alleviating liver injury.

[0083] Total triglyceride (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in the serum of mice were measured to characterize the blood lipid levels of mice. The results are as Figure 21-23As shown in the figure. After the intervention of hypoglycemic peptide segments AGM and KPAF, the serum TG levels decreased significantly, by 20.19% and 27.27% respectively; after the intervention of hypoglycemic peptide segments AGM and KPAF, the serum TC levels were significantly improved, decreased by 20.19% and 19.07% respectively; after the intervention of hypoglycemic peptide segments AGM and KPAF, the serum TC levels were significantly improved, decreased by 34.88% and 38.54% respectively, indicating that the intervention of camel milk endogenous peptides can effectively improve the blood lipid levels of insulin-resistant mice and relieve their lipid deposition.

[0084] The levels of total triglyceride (TG) and total cholesterol (TC) in the livers of mice were measured, and the results are as Figure 24-25 shown. After the intervention of hypoglycemic peptide segments AGM and KPAF, the levels of total triglyceride and total cholesterol in the liver decreased significantly. Among them, the triglyceride decreased by 44.71% and 47.16% respectively compared with the HFD group; the total cholesterol decreased by 36.70% and 47.15% respectively compared with the HFD group, indicating that the peptide intervention significantly improved the liver lipid levels of high-fat diet mice and improved liver lipid accumulation.

[0085] The DPP-IV activity in the serum of mice was measured, and the results are as Figure 26 shown. After the intervention of hypoglycemic peptide segments AGM and KPAF, the serum DPP-IV activity levels decreased significantly, by 42.67% and 35.18% respectively, indicating that the peptide intervention played a role in inhibiting DPP-IV activity.

[0086] The mRNA expression of GPR-40 in the colon of mice was measured, and the results are as Figure 27 shown. After the intervention of hypoglycemic peptide segments AGM and KPAF, the relative mRNA expression of GPR-40 in the colon increased significantly, indicating that the peptide intervention reduces glucose and improves insulin resistance by enhancing glucose-stimulated insulin secretion.

[0087] 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 scope of protection of the present invention.

Claims

1. An application of an endogenous camel milk hypoglycemic peptide with hypoglycemic effect in the preparation of a product with DPP-IV inhibitory activity and GPR-40 agonist activity, wherein the amino acid sequence of the endogenous camel milk hypoglycemic peptide is: AGM, as shown in SEQ ID NO.

1.

2. An application of an endogenous camel milk hypoglycemic peptide with hypoglycemic effect in the preparation of a product with DPP-IV inhibitory activity and GPR-40 agonist activity, wherein the amino acid sequence of the endogenous camel milk hypoglycemic peptide is: KPAF, as shown in SEQ ID NO.

2.

3. Use of a camel milk endogenous glucose-lowering peptide composition with hypoglycemic effect in the preparation of a product with DPP-IV inhibitory activity and GPR-40 agonist activity, wherein the amino acid sequence of the camel milk endogenous glucose-lowering peptide comprises one or both of AGM and / or KPAF.

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