A cyclic peptide that reduces insulin while appropriately reducing blood glucose

Abstract

The application is a bifunctional cyclic peptide which reduces insulin and does not increase blood sugar but appropriately reduces blood sugar, and belongs to the technical field of biological medicine. 52‑69 The cyclic peptide is obtained by in-vitro modification and reformation on the basis of the original linear short peptide COX The application realizes the seemingly contradictory two aspects of functions, i.e. inhibiting insulin secretion while not increasing blood sugar, and even reducing blood sugar, and the mechanism may be that the sensitivity of the tissue to insulin is improved. We call it a bifunctional peptide. The bifunctional peptide can be used for congenital hyperinsulinemia, insulin resistance, high insulin of obese people, etc. Literature reports that the increase of insulin is the cause of obesity, but for a long time, we cannot reduce weight by reducing insulin because the blood sugar will increase after the reduction of insulin, and high blood sugar is more harmful to health. The cyclic peptide realizes the function of reducing insulin while the blood sugar does not increase, but is reduced, which opens up a new way for weight loss of obesity, and the peptide can be conveniently administered orally in addition to injection. The convenience of use is greatly improved.

Description

[0001] This invention relates to a bifunctional cyclic peptide that both lowers insulin levels and appropriately lowers blood glucose, belonging to the field of biopharmaceutical technology. The bifunctional cyclic peptide is obtained through in vitro modification of the existing linear short peptide COX52-69, achieving seemingly contradictory effects: inhibiting insulin secretion without raising blood glucose levels, and even lowering blood glucose. The mechanism may be improved tissue sensitivity to insulin. We call this a bifunctional peptide. Technical Field

[0002] This invention relates to a method that inhibits insulin secretion without increasing blood glucose levels; on the contrary, it has a certain blood glucose-lowering effect. This is a phenomenon that has not been discovered before. This invention belongs to the field of biochemical pharmaceutical peptides. Background Technology

[0003] As is well known, insulin is currently the only hormone that lowers blood sugar; when insulin levels decrease, blood sugar levels rise. Medications for high blood sugar all work by promoting insulin secretion, thereby lowering blood sugar. Currently, there is no drug that lowers insulin levels without raising blood sugar, and even fewer drugs that lower insulin levels while simultaneously lowering blood sugar. Summary of the Invention

[0004] We previously obtained a patent for cytochrome C oxidase VIII. 52-69 The patent number is ZL201310471571.9, which describes the preparation method and function of the material. This is a linear polypeptide, which we call COX. 52-69The linear peptide, after oral administration, is enzymatically hydrolyzed, losing its function of inhibiting insulin secretion. Therefore, after modifying this linear peptide into a cyclic peptide and making some further modifications, we obtained a cyclic peptide that not only achieved oral administration but also, while inhibiting insulin secretion, did not increase blood glucose levels; instead, it lowered them. Currently, no other drug or reagent possesses such a dual function. The mechanism may be that the cyclic peptide increases tissue sensitivity to insulin while lowering insulin levels, thereby reducing blood glucose. This will have significant applications in hyperinsulinemia, insulin resistance, and hyperinsulinemia in obese individuals. In people with hyperinsulinemia, lowering insulin levels leads to elevated blood glucose, worsening diabetes. However, this cyclic peptide can lower insulin levels without raising blood glucose; in fact, it can lower them. This greatly expands its applicability. Literature reports that elevated insulin is a cause of obesity, but we have not been able to lose weight by lowering insulin because lowering insulin levels leads to elevated blood glucose, which is diabetes, and diabetes has many detrimental health consequences. Our cyclic peptide lowers insulin levels without raising blood sugar, thus reducing it. This opens up new avenues for obesity treatment. Furthermore, this drug can be conveniently administered both by injection and orally, greatly improving the ease of use.

[0005] Specifically, the present invention provides a cyclic peptide with dual functions of lowering insulin and lowering blood sugar.

[0006] The amino acid sequence of the cyclic peptide is: C*LLPAGWV-[N-Me-Leu]-SHLDSYKKREC*, and its structural formula is as follows: Figure 1 .

[0007] The main research process of this invention is as follows: First, through in vitro modification, the short peptide COX... 52-69 The molecular structure was modified, and the peptide was co-cultured in simulated gastrointestinal fluid in vitro. The co-incubated product was detected using HPLC-MS (High-Performance Liquid Chromatography-Mass Spectrometry). Subsequently, the insulin content and blood glucose concentration in the tail vein of rats at different time points were detected using a rat insulin ELISA kit and a blood glucose meter. The results showed that the peptide was stably present in simulated gastrointestinal fluid in vitro; in in vivo animal experiments, the cyclic peptide reduced insulin secretion from glucose-stimulated pancreatic islets while also appropriately lowering blood glucose levels.

[0008] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows: Through in vitro modification of the short peptide COX... 52-69This allows it to exist stably in simulated gastrointestinal fluid, improving the stability of oral administration of protein and peptide drugs. In in vivo experiments, through gavage administration, it was found that the peptide can inhibit glucose-induced insulin secretion from pancreas and reduce the magnitude of blood glucose rise, which is essentially a reduction in blood glucose compared with the control group.

[0009] The technical or experimental effects are compared.

[0010] This invention uses the cyclic peptide COX 52-69 The following experiments were conducted:

[0011] Using cyclic peptide COX 52-69 The product was co-incubated with simulated gastrointestinal fluid, and the incubated product was detected using HPLC-MS (High Performance Liquid Chromatography-Mass Spectrometry). Figure 2 This cyclic peptide is well tolerated by gastrointestinal fluids, meaning it can be taken orally.

[0012] The experimental group used the modified peptide COX 52-69 SD rats were administered the drug via gavage, while the control group received the same dose of 0.9% saline via gavage. Both groups were also administered 20% glucose solution via gavage. Blood samples were collected from the tail vein at 0, 30, 60, 90, and 120 minutes. The insulin content in the blood supernatant was detected using ELISA (enzyme-linked immunosorbent assay). Figure 3 The peak insulin concentration in the experimental group was significantly lower than that in the control group, with a statistically significant difference; simultaneously, blood glucose concentrations at the above time points were measured using a blood glucose meter. Figure 4 The peak blood glucose level in the experimental group was significantly lower than that in the control group, indicating a statistically significant difference. This suggests that the cyclic peptide did not cause an increase in blood glucose while reducing insulin levels, but rather had a blood glucose-lowering effect. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 The cyclic peptide COX provided in this embodiment of the invention 52-69 Structural diagram.

[0015] Figure 2 It is a cyclic peptide COX 52-69 A schematic diagram of HPLC-MS detection after incubation with simulated gastrointestinal fluid.

[0016] Figure 3 It is the cyclic peptide COX administered orally to SD rats.52-69 A schematic diagram showing serum insulin levels detected by ELISA.

[0017] Figure 4 It is the cyclic peptide COX administered orally to SD rats. 52-69 A diagram illustrating changes in blood glucose levels detected by a blood glucose meter. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, a brief description is provided below in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0019] In view of the problems existing in the prior art, the present invention provides a dual-function polypeptide that lowers blood sugar and insulin. The present invention will be described in detail below with reference to the accompanying drawings.

[0020] The amino acid sequence of the modified peptide is SEQ ID NO: 1, which is: C*LL PAGWV-[N-Me-Leu]-SHLDSYKKREC*.

[0021] Example 1:

[0022] To assess the stability of this peptide in the gastrointestinal tract, it was incubated in simulated gastrointestinal fluid in vitro, and the results were analyzed by HPLC-MS. The short peptide COX was found to have... 52-69 It can exist stably in simulated gastrointestinal fluid.

[0023] Example 2:

[0024] The experimental group used the modified peptide COX 52-69 SD rats were administered the drug via gavage, while the control group received the same dose of 0.9% saline via gavage. Both groups were also administered 20% glucose solution via gavage. Blood samples were collected from the tail vein at 0, 30, 60, 90, and 120 minutes. The insulin content in the blood supernatant was detected using ELISA (enzyme-linked immunosorbent assay). Figure 3 The insulin concentration in the experimental group was significantly lower than that in the control group, with a statistically significant difference; simultaneously, blood glucose concentrations at the above time points were measured using a blood glucose meter. Figure 4 The experimental group showed a significantly lower increase in blood glucose than the control group, indicating that the cyclic peptide lowered insulin levels without raising blood glucose, but rather had a blood glucose-lowering effect. Lowering insulin without raising blood glucose can be used in many cases of high insulin levels, such as hyperinsulinemia in obese individuals.

[0025] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A cyclic peptide COX 52-69 for use in the preparation of a medicament for lowering blood glucose while lowering insulin, the amino acid sequence of which is: C*L L P A G W V-[N-Me-Leu]-SHLDSYKKREC*, the structural formula of which is: 。 2. Use according to claim 1, characterized in that The medicament is in the form of an oral dosage, an injection, an intravenous or a mucosal absorption dosage.

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