Cyclic peptide and application thereof

Abstract

The invention discloses a cyclic peptide and application thereof. The invention provides a novel cyclic peptide which is not reported, and the novel cyclic peptide has an extremely strong affinity effect on an LRR structural domain in NLRP3 protein, so that the activation of NLRP3 inflammasome can be inhibited. Technicians in the field know that NLRP3 inflammatory bodies can be activated by various types of pathogens and danger signals, and play an important role in various diseases, such as inflammatory diseases and tumors. Experiments prove that the novel cyclopeptide has excellent anti-tumor activity and anti-inflammatory activity. Therefore, the novel cyclopeptide provided by the invention has the prospect of being developed into drugs for treating diseases which can be treated or relieved by inhibiting NLRP3 inflammasome activation, such as anti-tumor drugs and anti-inflammatory drugs.

Description

Technical Field

[0001] The present invention belongs to the field of polypeptides, relates to novel polypeptides and applications, and specifically relates to a cyclic peptide and applications thereof. Background Art

[0002] As a "therapeutic drug molecule", cyclic peptides are the absolute main force in the field of cyclic peptide drugs. Compared with linear peptides, cyclic peptides have better structural rigidity and protein resistance, and can obtain longer half-life and action time. Linear peptides are relatively unstable to exopeptidases, while cyclic peptides cyclized by terminal amino acids can greatly slow down the degradation of exopeptidases. And a molecule must adopt a certain conformation when binding to a target. Since linear peptides have fewer conformational restrictions, the possibility of binding to the target in a suitable conformation per unit time is small, and the entropy penalty is greater. The possibility that cyclic peptide molecules may be in or close to this binding peptide conformation is higher, and they have stronger target affinity.

[0003] NLR family protein 3 (NLRP3) inflammasome is a macromolecular multiprotein complex composed of NLRP3, adaptor protein ASC and effector protein Caspase-1. NLRP3 inflammasome can be activated by various types of pathogens and danger signals, and therefore plays an important role in many diseases. The normal activation of NLRP3 inflammasome helps the host resist infection by pathogenic microorganisms and maintain the stability of the body's internal environment. When NLRP3 inflammasome is overactivated, various inflammatory diseases will occur (Li Chenguang et al., Research Progress of NLRP3 Inflammasome Inhibitors, Chinese Pharmacological Bulletin, 2024). NLRP3 inflammasome also plays an important role in the occurrence and development of tumors. Inhibiting NLRP3 inflammasome activation helps inhibit tumors (Chen Xiuhui et al., The Role of NLRP3 Inflammasome in Tumors and Research Progress of Its Inhibitors, Central South Pharmacy, 2023).

[0004] The activation of NLRP3 inflammasome requires both the first and second signals. The first signal includes different TLR (Toll-like receptor) ligands, such as LPS or other danger signals, which mainly upregulate the protein expression of NLRP3 and pro-IL-1β by activating the NF-κB pathway. The second signal includes some crystalline substances (such as uric acid crystals, silica, asbestos and aluminum), extracellular ATP, perforin toxins, mitochondrial DNA and pathogen-related components. The regulators of NLRP3 inflammasome activation that have been reported include double-stranded RNA dependent protein kinase (PKR), guanylate-binding protein 5 (GBP5) and NIMA-related kinase 7 (Nek7). Unlike PKR and GBP5, three independent studies have shown that Nek7 plays an important role in the activation of NLRP3 inflammasome. Nek7 belongs to the NIMA (never-in-mitosisA) related kinase family and is mainly involved in regulating the mitotic process and DNA damage response. Related studies have shown that all NLRP3 stimuli (including ATP, nigericin, MSU crystals and alum) induced activation of NLRP3 inflammasomes require Nek7, while activation of inflammasomes such as NLRC4 and AIM2 does not require Nek7. The catalytic region of Nek7 and the LRRs region of NLRP can interact to form a NLRP3-Nek7 macromolecular complex, and NLRP3 agonists can enhance this effect. Nek7-mediated activation of NLRP3 is independent of its kinase activity. Nek7 in K + The downstream of outflow can regulate the oligomerization of NLRP3, the formation of ASC spots and the activation of Caspase-1. Therefore, exploring the response mechanism of Nek7 to NLRP3 agonists will provide new ideas for the study of the molecular mechanism of NLRP3 inflammasome activation.

[0005] Targeted inhibition of NLRP3 inflammasome provides a new approach for the treatment of related diseases. A variety of synthetic small molecules and natural products have emerged as NLRP3 inflammasome inhibitors, which show potential in specificity and efficacy. However, most of the NLRP3 inhibitors entering clinical research are MCC950 analogs, which have the problems of a single skeleton and severe structural homogeneity, which limits the diversity of the drug and its therapeutic effect.

[0006] Based on the discovery of the novel cyclic peptide and its activity, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a cyclic peptide, and the second purpose is to provide the use of the cyclic peptide.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] A cyclic peptide or a pharmaceutically acceptable salt or solvate thereof, wherein the cyclic peptide comprises the following sequence:

[0010] LSRMIKHFKKQ.

[0011] Preferably, the cyclic peptide comprises the following sequence:

[0012] CLSRMIKHFKKQC.

[0013] More preferably, the sequence of the cyclic peptide is as shown in SEQ ID NO.1 or SEQ ID NO.5:

[0014] SEQ ID NO.1: Ac-CLSRMIKHFKKQC-NH2, cyclization site is c[1C-13C];

[0015] SEQ ID NO.5: CGDCLSRMIKHFKKQCKRLIC, the cyclization sites are c[1C-16C] and c[4C-21C].

[0016] Preferably, the cyclic peptide comprises the following sequence:

[0017] GDLSRMIKHFKKQKRLI.

[0018] More preferably, the sequence of the cyclic peptide is as shown in SEQ ID NO.2, SEQ ID NO.3 or SEQ ID NO.4:

[0019] SEQ ID NO.2: Ac-GDLSRMIKHFKKQKRLIQ, cyclization site is c[8K-18Q];

[0020] SEQ ID NO.3: Ac-CGDLSRMIKHFKKQKRLIC-NH2, cyclization site is c[1C-19C];

[0021] SEQ ID NO.4: RRRRRRRRCGDLSRMIKHFKKQKRLIC, the cyclization site is c[10C-28C].

[0022] The use of the above-mentioned cyclic peptide or its pharmaceutically acceptable salt or solvate for preparing an inhibitor of NLRP3 inflammasome activation, or for preparing a drug for a disease that can be treated or alleviated by inhibiting NLRP3 inflammasome activation.

[0023] Preferably, the disease that can be treated or alleviated by inhibiting NLRP3 inflammasome activation is a tumor.

[0024] More preferably, the tumor is leukemia.

[0025] More preferably, the disease that can be treated or alleviated by inhibiting NLRP3 inflammasome activation is an inflammatory disease.

[0026] Beneficial effects:

[0027] The present invention provides a novel cyclic peptide that has not been reported, which has a strong affinity for the LRR domain in the NLRP3 protein, thereby inhibiting the activation of the NLRP3 inflammasome. Those skilled in the art know that the NLRP3 inflammasome can be activated by various types of pathogens and danger signals, and plays an important role in various diseases, such as inflammatory diseases and tumors. The present invention has proved through experiments that the novel cyclic peptide has excellent anti-tumor activity and anti-inflammatory activity. It can be seen that the novel cyclic peptide provided by the present invention has the prospect of being developed into a drug for treating diseases that can be treated or alleviated by inhibiting the activation of the NLRP3 inflammasome, such as anti-tumor drugs and anti-inflammatory drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The CD spectrum structure diagram of the cyclic peptides Cy-1, Cy-2, Cy-3, Cy-4 and Cy-5 of the present invention dissolved in 1×PBS (containing 50% TFE) in the range of 190-260nm (concentration is 0.1mg / ml);

[0029] Figure 2 The graph is a concentration-inhibition rate curve of the cyclic peptides Cy-1, Cy-2, Cy-3, Cy-4, and Cy-5 of the present invention on the LRR domain of the NLRP3 protein in buffer (50 mM Tris-HCl, 10 mM NaCl, 1 mM EDTA, pH 8.8). DETAILED DESCRIPTION

[0030] The essential contents of the present invention are described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0031] Example 1: Preparation and characterization of cyclic peptides

[0032] The target cyclic peptide was synthesized by conventional cyclic peptide synthesis methods in the art. The cyclic peptide sequence is as follows, where "Ac" represents acetylation of the N-terminus of the cyclic peptide and "NH2" represents amidation of the C-terminus of the cyclic peptide:

[0033] SEQ ID NO. name sequence Cyclization site SEQ ID NO.1 Cy-1 <![CDATA[Ac-CLSRMIKHFKKQC-NH2]]> c[1C-13C] SEQ ID NO.2 Cy-2 Ac-GDLSRMIKHFKKQKRLIQ c[8K-18Q] SEQ ID NO.3 Cy-3 <![CDATA[Ac-CGDLSRMIKHFKKQKRLIC-NH2]]> c[1C-19C] SEQ ID NO.4 Cy-4 RRRRRRRRRCGDLSRMIKHFKKQKRLIC c[10C-28C] SEQ ID NO.5 Cy-5 CGDCLSRMIKHFKKQCKRLIC c[1C-16C]&c[4C-21C]

[0034] The synthesis method is as follows:

[0035] The cyclic peptides were synthesized manually by solid phase peptide synthesis (SPPS) method; the synthesis scale was 0.1 mmol, 40-RAM amphiphilic Rink amide resin was loaded at 0.4 mmol / g, and 5 equivalents were used for protected amino acids; all protected amino acids and coupling agent HATU were pre-dissolved in DMF to prepare a stock solution with a concentration of 0.5 M; the resin was first placed in 6 ml of The mixture was swelled in DMF for 30 minutes. After removing DMF by filtration, the Fmoc group was deprotected by adding 20% ​​piperidine / DMF solution (6 ml) and vortexing for 1 minute. After the above steps were performed twice, the resin was washed with DMF 3 times, and the required amino acid (1 ml, 0.5 mmol), N,N-diisopropylethylamine (DIEA) (0.164 ml, 1 mmol) and HATU coupling agent (1 ml, 0.5 mmol) were added in sequence and stirred under vortex stirring for 5 minutes. Between the two couplings, the operation was performed twice by washing with DMF. The Fmoc deprotection and amino acid coupling were repeated until the expected linear sequence was obtained. After the linear peptide was synthesized, it was cyclized by iodine oxidation, I2 (25 mg, 0.1 mmol) was added, and 6 mL DMF, react under vortex stirring for 2 hours, after which the resin is washed 3 times with DMF, the final Fmoc group is deprotected after cyclization, and an acetylation reaction is carried out for 10 minutes using a DMF solution of acetic anhydride containing DIEA (1 / 1 / 8), and the final cleavage of the peptide is carried out in the presence of a solution (10 ml) of trifluoroacetic acid, triisopropylsilane and water (95 / 2.5 / 2.5); after filtration, the solution is concentrated and dissolved in ether; the precipitate is centrifuged and the mother liquor is decanted; the above steps are carried out twice, the precipitate is dissolved in water and lyophilized to obtain a completely deprotected peptide; after lyophilization, the cyclic peptide is purified by elution with acetonitrile / water on a preparative reverse phase HPLC in the presence of 0.1% TFA; the cyclic peptide thus obtained preferably has a purity greater than 95%.

[0036] The cross-linked compound was purified by high performance liquid chromatography on a reverse phase C18 column to obtain a pure compound; the chemical composition of the pure product was confirmed by LC / MS mass spectrometry and amino acid analysis. The mass spectrometry data and purity of each target cyclic peptide are as follows:

[0037] SEQ ID NO. name Calculated m / z(M+2H) Observed m / z(M+2H) purity(%) SEQ ID NO.1 Cy-1 831.5 831.3 95.16 SEQ ID NO.2 Cy-2 1126.4 1126.2 99.35 SEQ ID NO.3 Cy-3 1172.9 1172.8 98.72 SEQ ID NO.4 Cy-4 1855.3 1855.1 99.61 SEQ ID NO.5 Cy-5 1254.6 1254.2 98.18

[0038] Example 2: Evaluation of whether cyclic peptides maintain their α-helical structure in an amphipathic cell membrane mimicking environment

[0039] In order to further understand the effect of α-helix structure on the biological activity of cyclic peptides, and taking advantage of the characteristic of trifluoroethanol in promoting the formation of α-helix secondary structure, circular dichroism spectroscopy was performed on the cyclic peptides. In the far ultraviolet region (185-245nm) of the CD spectrum, the typical secondary structures of cyclic peptides have their own characteristic absorption peaks. Among them, α-helix shows double negative peaks at 208nm and 222nm, and a positive peak at 195nm; β-folding will have a weaker negative peak at 215nm; random curling has a negative peak at 200nm and a small and wide positive peak at 220nm.

[0040] The secondary structure of the cyclic peptide was determined by circular dichroism spectroscopy. The CD spectrum was measured using a J-810 spectrometer at 25°C using a quartz cell with an optical path of 1.0 mm, and recorded by scanning in the range of 190 to 260 nm; the speed was 50 nm / min, the bandwidth was 1 nm, and the response was 1 s; the cyclic peptide was dissolved in a 50% trifluoroethanol solution prepared by PBS (cell membrane simulation environment) to prepare a cyclic peptide solution with a concentration of 0.1 mg / mL; each spectrum was the result of 3 average accumulations; and the acquired CD spectrum was then converted to the average residual ellipticity using the following formula:

[0041] [θ] 222 =([θ] obs ×MW) / (L×ρ);

[0042] Where: [θ] 222 is the average residual ellipticity at 222 nm (deg*cm2*dmol-1), [θ]obs is the observed ellipticity corrected for buffer at a wavelength of 222 nm (mdeg), MW is the average residual molecular mass of the cyclic peptide, ρ is the mass concentration of the cyclic peptide (mg / ml), and L is the cuvette optical path length of 1 mm.

[0043] The α-helix content was calculated according to the following formula:

[0044] α-helix content (%) = -([θ] 222 ×100) / 40000.

[0045] The obtained CD spectrum is shown as the average residual ellipticity [θ] (deg*cm 2 *dmol -1 ) versus wavelength λ(nm).

[0046] like Figure 1As shown, in the amphiphilic cell membrane simulation environment, the cyclic peptides Cy-1 and Cy-4 both have good α-helical structure, showing a positive peak at 195nm and double negative peaks at 208nm and 222nm; the α-helicity of Cy-1-Cy-5 are 16.69%, 14.99%, 39.42%, 8.75%, and 18.58%, respectively.

[0047] Example 3: Evaluation of the inhibitory activity of cyclic peptides on the LRR domain in NLRP3 protein

[0048] 1. Experimental Materials

[0049] The LRR domain recombinant protein was purchased from Zhongding Biotechnology Co., Ltd., Tris-HCl, NaCl, and EDTA were all purchased from Sangon Biotech, and the fluorescent probe FITC-Acp-LSRMIKHFKKQ-NH2 was synthesized by Shanghai Sangon Biotechnology Co., Ltd.; multifunctional microplate reader (Thermo), 384-well low-edge black flat-bottom polystyrene NBS microplate (Corning), etc.

[0050] 2. Experimental Methods

[0051] 1. Experimental principle: In order to detect the binding inhibitory activity of Cy-1, Cy-2, Cy-3, Cy-4 and Cy-5 on the LRR domain in the NLRP3 protein, the inhibition rate was determined based on the fluorescence polarization technology. The fluorescent substance is labeled on a specific substance with the fluorescence labeling detection technology, so that the originally weak reaction signal is converted into a stronger fluorescence signal, which plays a role in signal enhancement. At the same time, a polarizer and an analyzer are added to the detection system. When a beam of light emitted from the light source becomes vertically polarized light after passing through the vertical polarizer, the sample is excited by the vertically polarized light to produce polarized fluorescence. This fluorescence can be measured by the analyzer. The intensity of horizontal or vertical fluorescence polarization light related to the sample concentration can be measured. The working curve is made by the fluorescence intensity and sample concentration for quantitative analysis. When the fluorescent probe binds to the protein, the molecular weight becomes larger, the rotation speed becomes slower, and the mP value increases. Therefore, when the compound is an active substance, the fluorescent probe competes with the compound for binding to the protein, the probe binds less to the protein, and the mP value decreases; when the compound is an inactive substance, the fluorescent probe is more likely to bind to the protein, and the mP value increases. According to the change of the system mP value, the inhibition rate of the cyclic peptide was calculated to obtain the binding inhibitory activity of the cyclic peptide on the LRR domain.

[0052] 2. Detection method: 10mmol·L -1 Cy-1, Cy-2, Cy-3, Cy-4, and Cy-5 were diluted 2-fold (initial concentration 100 μmol·L) in fluorescence polarization reaction solution (50 mM Tris-HCl, 10 mM NaCl, 1 mM EDTA, pH 8.8).-1 , a total of 12 concentration gradients were diluted), added to a 384-well plate, 20 μL per well, and 3 sets of replicate wells were set up for each group. Then 375 nmol·L - 1 LRR, 20 μL per well, incubated at room temperature for 30 min. -1 The fluorescent probes were added to the 384-well plate in sequence (all at final concentrations), 20 μL per well, and incubated at room temperature for 30 min. The mP value was detected by a multifunctional microplate reader. The inhibition rate of the cyclic peptide on the LRR domain was calculated as follows (the wells containing 2% DMSO were used as negative control wells, and the wells containing only 10 nM fluorescent probes were used as positive control wells):

[0053] Inhibition rate (%) = (1 - (mP value of drug well - mP value of positive well) / (mP value of negative well - mP value of positive well)) * 100%.

[0054] 3. Experimental Results

[0055] The inhibitory activity of Cy-1, Cy-2, Cy-3, Cy-4 and Cy-5 on the LRR domain of NLRP3 protein Figure 2 As shown, its IC 50 They are 0.8117 μM, 4.274 μM, 0.4926 μM, 0.3418 μM and 0.5426 μM respectively, indicating that the cyclic peptides of the present invention have extremely strong binding inhibitory activity on the LRR domain in the NLRP3 protein.

[0056] Example 4: Evaluation of the anti-tumor activity of cyclic peptides by CCK8 method

[0057] 1. Experimental Materials

[0058] 1. Instruments and reagents

[0059] Instruments: clean bench, centrifuge (Thermo), cell incubator, E1x800 microplate reader (BioTek, Vermont, USA), etc. 1640 culture medium (Nanjing KeyGene Biotechnology Co., Ltd.), Brazilian fetal bovine serum, and CCK8 reagent were purchased from TargetMol.

[0060] 2. Experimental cells

[0061] THP-1 cells (human monocytic leukemia cells) were obtained from the cell bank of the Chinese Academy of Sciences.

[0062] 2. Experimental Methods

[0063] 1. Culture of THP-1 cells

[0064] (1) Complete culture medium: RPM-1640 culture medium 90%, fetal bovine serum 10%.

[0065] (2) Incubator environment: 37°C, air 95%, carbon dioxide 5%.

[0066] (3) Cell plating: Take THP-1 cells in good condition, transfer to a centrifuge tube and centrifuge (800rpm, 5min), discard the supernatant, add culture medium, blow evenly, count, and supplement the culture medium to make the cell concentration around 100,000 / ml, blow evenly. Take a 96-well plate, add 100ul of cell suspension to each well, so that the number of cells in each well is about 10,000 / well, and ensure that the cell concentration in each well is uniform. After adding, gently shake the 96-well plate to evenly disperse the cells and place it in an incubator for culture.

[0067] 2. CCK8 Experiment

[0068] The experiment was divided into a blank control (DMSO) and a drug-treated group (cyclic peptide Cy-4). The anti-tumor activity of the cyclic peptide Cy-4, which had the strongest inhibitory activity on the binding of the LRR domain in the NLRP3 protein, was determined by using the CCK8 method. After THP-1 cells were treated with a density gradient of the test cyclic peptide or DMSO for 24 hours, 10 μL of CCK8 solution was added to each well of the 96-well plate and incubated for 3 hours. The absorbance value (OD value) was recorded at 450 nm by an E1x800 absorbance microplate reader. The cell growth inhibition rate of the cyclic peptide was calculated as follows (the cell wells without drug addition were used as blank controls): inhibition rate (%) = (1-drug well OD value / blank well OD value) × 100%. The IC was obtained according to the inhibition rate at different concentrations. 50 value.

[0069] 3. Experimental Results

[0070] The results showed that compared with the control group, the cyclic peptide Cy-4 had a stronger inhibitory activity against human monocytic leukemia THP-1 cells, IC 50 =8.023μM.

[0071] Example 5: Evaluation of the anti-inflammatory activity of cyclic peptides by ELISA

[0072] 1. Experimental Materials

[0073] 1. Instruments and reagents

[0074] Instruments: clean bench, centrifuge (Thermo), cell incubator, full-wavelength microplate reader (Thermo), etc.: 1640 culture medium (Nanjing KeyGene Biotechnology Co., Ltd.), Brazilian fetal bovine serum, Human IL-1beta Uncoated ELISA Kit purchased from Thermo Fisher Scientific Co., Ltd., Phorbol 12-myristate 13-acetate (PMA, Abcam), LPS (Sigma-Aldrich), ATP (Sigma-Aldrich).

[0075] 2. Experimental cells

[0076] THP-1 cells (human monocytic leukemia cells) were obtained from the cell bank of the Chinese Academy of Sciences.

[0077] 2. Experimental Methods

[0078] 1. Culture of THP-1 cells

[0079] (1) Complete culture medium: RPM-1640 culture medium 90%, fetal bovine serum 10%.

[0080] (2) Incubator environment: 37°C, air 95%, carbon dioxide 5%.

[0081] (3) Cell plating and differentiation induction: Take THP-1 cells in good condition, transfer to a centrifuge tube for centrifugation (800rpm, 5min), discard the supernatant, add culture medium, blow evenly, count, supplement the culture medium to make the cell concentration about 500,000 / ml, add PMA to make its final concentration 100ng / ml, and blow evenly. Take a 96-well plate, add 100ul of cell suspension to each well, make the number of cells in each well about 50,000 / well, and ensure that the cell concentration in each well is uniform. After adding, gently shake the 96-well plate to evenly disperse the cells, place it in an incubator and culture it for 12h, and induce it to differentiate into macrophages, which is a commonly used anti-inflammatory cell model in this field.

[0082] (4) Modeling and drug administration: Use a pipette to gently remove the supernatant, add the pre-prepared Cy-4 solution along the wall, add equal amounts of 1640 medium to the blank group and the model group, and culture in the incubator for 24 hours. Use 1640 medium to prepare 10μg / ml LPS working solution, add an appropriate amount to each well to make the final concentration of LPS 500ng / ml, and continue to culture for 3 hours. Use PBS to prepare 100mg / ml ATP working solution, add an appropriate amount to each well to make the final concentration of ATP 5mM, and continue to culture for 1 hour.

[0083] 2. Enzyme-linked immunosorbent assay (ELISA)

[0084] (1) Grouping: DMSO blank group and LPS+ATP modeling group were used as negative controls, and LPS+ATP+Cy-4 administration group was used as the experimental group.

[0085] (2) Methods: Human IL-1beta Uncoated ELISA Kit was used to determine the anti-inflammatory activity of the cyclic peptide Cy-4 with the strongest inhibitory activity against the LRR domain of NLRP3 protein. Freshly collected THP-1 cell samples were allowed to stand at room temperature for 20 minutes, and then centrifuged at 4°C and 3000g for 10 minutes. The supernatant was used for detection and analysis. THP-1 cell samples and IL-1β standards were added to 96-well plates coated with antibodies, and the plates were incubated on a shaker at 37°C for 1 hour after adding biotinylated antibodies. The plates were washed 5 times, enzyme binding working solution was added, and the plates were incubated at 37°C in the dark for 30 minutes, and then washed 5 times. The colorimetric substrate was added and incubated at 37°C in the dark for 15 minutes. The reaction was terminated by adding the stop solution. The absorbance value was measured at a wavelength of 450 nm using a full-wavelength microplate reader within 10 minutes. The inhibition rate of Cy-4 on interleukin IL-1β was calculated as follows: inhibition rate (%) = 1-(OD value of drug well-OD value of blank well) / (OD value of negative control well-OD value of blank well), three replicate wells were set, and the inhibition rate of cyclic peptide on IL-1β was expressed as the mean ± SEM of each group of data.

[0086] 3. Experimental Results

[0087] The results showed that the cyclic peptide Cy-4 had a strong inhibitory activity against interleukin IL-1β. The inhibition rate of 10μM Cy-4 against interleukin IL-1β was (37.02±6.78)%, and the inhibition rate of 50μM Cy-4 against interleukin IL-1β was as high as (104.34±0.12)%.

[0088] In summary, the present invention provides a novel cyclic peptide that has not been reported, and the novel cyclic peptide has a very strong affinity for the LRR domain in the NLRP3 protein, thereby inhibiting the activation of the NLRP3 inflammasome. Those skilled in the art know that the NLRP3 inflammasome can be activated by various types of pathogens and danger signals, and plays an important role in various diseases, such as inflammatory diseases and tumors. The present invention has proved through experiments that the novel cyclic peptide has excellent anti-tumor activity and anti-inflammatory activity. It can be seen that the novel cyclic peptide provided by the present invention has the prospect of being developed into a drug for treating diseases that can be treated or alleviated by inhibiting the activation of the NLRP3 inflammasome, such as anti-tumor drugs and anti-inflammatory drugs.

[0089] The purpose of the above-mentioned embodiments is to specifically introduce the essential content of the present invention, but those skilled in the art should know that the protection scope of the present invention should not be limited to the specific embodiments.

Claims

1. A cyclic peptide or a pharmaceutically acceptable salt or solvate thereof, characterized in that: The cyclic peptide contains the following sequence: LSRMIKHFKKQ.

2. The cyclic peptide or pharmaceutically acceptable salt or solvate thereof according to claim 1, characterized in that: The cyclic peptide contains the following sequence: CLSRMIKHFKKQC.

3. The cyclic peptide or pharmaceutically acceptable salt or solvate thereof according to claim 2, characterized in that: The sequence of the cyclic peptide is shown in SEQ ID NO.1 or SEQ ID NO.5: SEQ ID NO.1: Ac-CLSRMIKHFKKQC-NH2, cyclization site is c[1C-13C]; SEQ ID NO.5: CGDCLSRMIKHFKKQCKRLIC, the cyclization sites are c[1C-16C] and c[4C-21C].

4. The cyclic peptide or pharmaceutically acceptable salt or solvate thereof according to claim 1, characterized in that: The cyclic peptide contains the following sequence: GDLSRMIKHFKKQKRLI.

5. The cyclic peptide or pharmaceutically acceptable salt or solvate thereof according to claim 4, characterized in that: The sequence of the cyclic peptide is shown in SEQ ID NO.2, SEQ ID NO.3 or SEQ ID NO.4: SEQ ID NO.2: Ac-GDLSRMIKHFKKQKRLIQ, cyclization site is c[8K-18Q]; SEQ ID NO.3: Ac-CGDLSRMIKHFKKQKRLIC-NH2, cyclization site is c[1C-19C]; SEQ ID NO.4: RRRRRRRRCGDLSRMIKHFKKQKRLIC, the cyclization site is c[10C-28C].

6. Use of the cyclic peptide according to any one of claims 1 to 5 or a pharmaceutically acceptable salt or solvate thereof for preparing an inhibitor of NLRP3 inflammasome activation.

7. Use of the cyclic peptide according to any one of claims 1 to 5 or a pharmaceutically acceptable salt or solvate thereof for preparing a drug for a disease that can be treated or alleviated by inhibiting NLRP3 inflammasome activation.

8. The use according to claim 7, characterized in that: The disease that can be treated or alleviated by inhibiting NLRP3 inflammasome activation is tumor.

9. The use according to claim 8, characterized in that: The tumor is leukemia.

10. The use according to claim 7, characterized in that: The disease that can be treated or alleviated by inhibiting NLRP3 inflammasome activation is an inflammatory disease.

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