Antibacterial cyclic peptide as well as composition, preparation method and application thereof

Abstract

The invention discloses an antibacterial cyclic peptide and a composition, a preparation method and application thereof, the amino acid sequence of the antibacterial cyclic peptide is shown as a formula (I), and the antibacterial cyclic peptide is added with a corresponding auxiliary agent to prepare the composition; experiments prove that the antibacterial cyclic peptide has good antibacterial activity, and has good application prospects when being applied to preparation of drugs.

Description

Technical Field

[0001] The present invention relates to the field of biomedicine technology, and in particular to an antibacterial cyclic peptide and a composition thereof, as well as a preparation method and application thereof. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Antibiotics are mainly secondary metabolites produced by bacteria, fungi or other microorganisms or artificially synthesized analogs. Antibiotics are widely used in various infectious diseases. Excessive use of traditional antibiotics in clinical practice has produced many medically relevant drug-resistant strains.

[0004] Cationic antimicrobial peptides can represent a new class of antibiotics. Although the mode of action of cationic antimicrobial peptides has not been fully determined, all cationic amphiphilic antimicrobial peptides interact with cell membranes. The cell membrane is the main target of antimicrobial peptides. The aggregation of antimicrobial peptide molecules on the cell membrane will increase the permeability of the cell membrane, causing the cell membrane to lose its barrier function. The development of such drug resistance in microorganisms is mainly based on the formation of bacterial biofilms, which creates penetration barriers to drugs, nutrient restrictions, and genetic phenotype changes. Antimicrobial peptides have good anti-biofilm activity and can inhibit and remove biofilms. Therefore, it is unlikely that antimicrobial peptides targeting biofilm activity will cause microbial resistance.

[0005] α-helical and β-folded antimicrobial peptides are the two main types of cationic antimicrobial peptides. β-folded antimicrobial peptides include cyclic peptides fixed by intramolecular disulfide bonds, as well as peptides with covalent bonds from the N-terminus to the C-terminus, such as gramicidin S and gramicidin tyrosin. α-helical antimicrobial peptides are more linear molecules that exist in disordered structures in aqueous media, but they interact with hydrophobic cell membranes and assume an amphipathic helical state, such as moth hematin, magainin and melittin.

[0006] As a new type of antibiotic, antimicrobial peptides are not easy to cause microorganisms to develop drug resistance and have broad application prospects. However, antimicrobial peptides directly obtained from organisms are exclusive to other organisms and are difficult to be directly applied to the human body. In other words, this type of antimicrobial peptides are highly toxic to the human body and cannot be directly used as human medicines. Therefore, there is a strong demand for artificially synthesized peptide drugs. Summary of the invention

[0007] The purpose of the present invention is to provide an antimicrobial peptide and its pharmaceutical composition and application in order to solve the problems that antimicrobial peptides directly obtained from organisms are unstable and easily hydrolyzed in vivo. The antimicrobial peptide sequence is modified by stapled cyclization by artificial synthesis, which can improve the stability of the antimicrobial peptide while maintaining good antibacterial activity, and is widely used in market production.

[0008] Indolicidine (Ile-Leu-Pro-Trp-Lys-Trp-Pro-Trp-Trp-Pro-Trp-Arg-Arg-NH2) is an antimicrobial peptide isolated from the cytoplasmic granules of bovine neutrophils. It is composed of 13 amino acids and is one of the smallest natural linear antimicrobial peptides known so far. Indolicidin has a broad antimicrobial spectrum and has strong antimicrobial activity against a variety of aerobic Gram-negative bacteria, Gram-positive bacteria and fungi. This patent is based on the polypeptide sequence of Indolicidine. The amino acids therein are replaced with amino acids of similar properties and a small amount of modifiable functional amino acids, and then the functional amino acids are connected by chemical means to form a cyclic peptide to obtain a new antimicrobial peptide, which has the same level of antimicrobial activity as Indolicidine, and the stability of the antimicrobial peptide is improved by cyclization.

[0009] The technical solution of the present invention is as follows:

[0010] An antibacterial cyclic peptide, the amino acid sequence of which is shown in formula (I): H-Ile-Xaa2-Xaa3-Xaa4-Xaa5-Xaa6-Xaa7-Xaa8-Xaa9-Xaa 10 -Xaa 11 -Arg-Arg-NH2

[0011] Formula (I)

[0012] in:

[0013] Xaa2 is selected from Leu, Cys, Hcy, Pen or S5 amino acids;

[0014] Xaa3 is selected from Pro, Cys, Hcy, Pen or S5 amino acids;

[0015] Xaa4 is selected from Trp, Cys, Hcy, Pen or S5 amino acids;

[0016] Xaa5 is selected from Lys, Cys, Hcy, Pen or S5 amino acids;

[0017] Xaa6 is selected from Trp, Cys, Hcy, Pen or S5 amino acids;

[0018] Xaa7 is selected from Pro, Cys, Hcy, Pen or S5 amino acids;

[0019] Xaa8 is selected from Trp, Cys, Hcy, Pen or S5 amino acids;

[0020] Xaa9 is selected from Trp, Cys, Hcy, Pen or S5 amino acids;

[0021] XA 10 Selected from Pro, Cys, Hcy, Pen or S5 amino acids;

[0022] XA 11 Selected from Trp, Cys, Hcy, Pen or S5 amino acids;

[0023] in,

[0024] There are only two amino acids selected from Cys, Hcy, Pen or S5 amino acids;

[0025] Furthermore, when any amino acid at position i among Xaa2 to Xaa7 is replaced by Cys, Hcy, Pen or S5, 11 Another amino acid at position i+4 is simultaneously replaced with the same Cys, Hcy, Pen or S5 amino acid, and i and the amino acid at position i+4 are cross-linked to form a cyclic peptide, wherein the value of i is 2-7, including both ends.

[0026] According to a preferred embodiment, Xaa4 and Xaa8 are simultaneously replaced with the same Cys, Hcy, Pen or S5 amino acid, and are cross-linked at this position to form a cyclic peptide.

[0027] According to a preferred embodiment, Xaa7 and Xaa 11 At the same time, they are replaced by the same Cys, Hcy, Pen or S5 amino acid and cross-linked at this position to form a cyclic peptide.

[0028] According to a preferred embodiment, when the amino acids at positions i and i+4 are selected from one of Cys, Hcy or Pen, the amino acids at positions i and i+4 are connected via a cross-linking agent to form a cyclic peptide.

[0029] According to a preferred embodiment, the cross-linking agent is selected from one or more of m-dibrombenzyl, o-dibrombenzyl, p-dibrombenzyl or succinimide.

[0030] According to a preferred embodiment, when the amino acids at positions i and i+4 are S5 amino acids, the amino acids at positions i and i+4 are directly connected to form a cyclic peptide.

[0031] According to a preferred embodiment, the antibacterial cyclic peptide is shown in the sequence SEQ ID No. 1 to SEQ ID No. 78. According to a preferred embodiment, the S5 amino acid is: α-Me-Gly(Pentenyl)-OH.

[0032] According to a preferred embodiment, the N-terminus of the antibacterial cyclic peptide is amidated, the C-terminus is acetylated, and all L-configuration amino acids are replaced with D-configuration amino acids.

[0033] Another aspect of the present invention provides a composition comprising an acceptable adjuvant and the antibacterial cyclic peptide as described above or a pharmaceutically acceptable salt, ester or solvate thereof.

[0034] On the other hand, the present invention also provides the use of the antimicrobial cyclic peptide or its pharmaceutically acceptable salt, ester, solvate and pharmaceutical composition as described above in the preparation of a drug for controlling or preventing microbial infection, wherein the indications of the microbial infection include wound infection, acne, diabetic foot ulcer, athlete's foot, onychomycosis, tinea, furuncle, impetigo, cellulitis, staphylococcal scalded skin syndrome, septic arthritis and bacteremia.

[0035] The present application also provides a method for preparing an antibacterial cyclic peptide as described above, comprising the following steps:

[0036] Step 1: Using amide resin, Fmoc protected amino acid, coupling reagent and organic base as starting materials, react in a protected organic solvent to obtain Fmoc protected amino acid-amide resin coupling product;

[0037] Step 2: Use the solid phase method to couple amino acids with protective groups one by one to synthesize a linear peptide with fully protected side chains;

[0038] Step 3: Add a shearing agent to shear the linear peptide from the resin, freeze-dry under vacuum to obtain a crude peptide, and then purify it using preparative liquid chromatography;

[0039] Step 4: The crude cyclic peptide is obtained by binding the linear peptide, the cross-linking agent and the organic base in the liquid phase, and is directly purified by preparative liquid chromatography.

[0040] According to a preferred embodiment, C4, C8 or C 18 The reverse phase chromatographic column uses a high performance liquid chromatography method to perform AB linear elution to prepare pure peptides, and the elution rate is: 1-20 mL / min; wherein, the A mobile phase is an aqueous solution containing 0.01-0.5% TFA, and the B mobile phase is acetonitrile containing 0.01-0.5% TFA.

[0041] The present application also provides a pharmaceutical composition, comprising an acceptable adjuvant and the antibacterial cyclic peptide or a pharmaceutically acceptable salt, ester or solvate thereof as described above. The above composition can be a pharmaceutical composition or a health care product composition. The adjuvant includes but is not limited to a carrier, diluent, excipient or adjuvant well known to those skilled in the art.

[0042] The present application also provides the use of the aforementioned antimicrobial cyclic peptide or its pharmaceutically acceptable salt, ester, solvate and pharmaceutical composition thereof in the preparation of a drug for controlling or preventing microbial infection.

[0043] In an embodiment of the present invention, the synthesis of the antibacterial cyclic peptides, their stereoisomers, mixtures thereof, and pharmaceutically acceptable salts thereof as described herein can be carried out according to any conventional method known in the prior art, such as solid phase peptide synthesis [Stewart JMy Young JD, "Solid Phase Peptide Synthesis, 2nd edition", (1984), Pierce Chemical Company, Rockford, Illinois; Bodanzsky M.yBodanzsky A., "The practice of Peptide Synthesis", (1994), Springer Verlag, Berlin; Lloyd Williams P.et al., "Chemical Approaches to the Synthesis of Peptides and Proteins", (1997), CRC, Boca Raton, FL, USA], synthesis in solution, enzymatic synthesis [Kullmann W. "Proteases as catalysts for enzymic syntheses of opioidpeptides", (1980), J.Biol.Chem., 255(17), 8234-8238] or any combination thereof. The compound can also be obtained by fermentation of a genetically modified or unmodified bacterial strain for the purpose of producing the desired sequence, or by controlled hydrolysis of free peptides containing at least the desired sequence from a protein of animal, fungal or preferably plant origin. For example, a nucleic acid sequence encoding the polypeptide amino acid sequence described herein and optionally carrying out appropriate amino acid modifications can be used to produce the compounds of the present invention.

[0044] Merely by way of example, the method for obtaining the polypeptide compounds of the present invention, their stereoisomers and mixtures thereof may comprise the following stages:

[0045] - coupling an N-terminally protected and C-terminally free amino acid with an N-terminally free and C-terminally protected or bound to a solid support amino acid;

[0046] - Elimination of the group protecting the N-terminus;

[0047] - Repeat the coupling procedure and eliminate the group protecting the N-terminus until the desired peptide sequence is obtained;

[0048] - Elimination of the group protecting the C-terminus or cleavage of the solid support;

[0049] Preferably, the C-terminus is bound to a solid support and the process is carried out in solid phase, thus comprising coupling an N-terminally protected and C-terminally free amino acid with an amino acid with N-terminus free and C-terminus bound to a polymer support; eliminating the group protecting the N-terminus; and repeating this procedure as many times as necessary to obtain a compound of the desired length, ultimately the compound synthesized subsequently from cleavage of the initial polymer support.

[0050] Throughout the synthesis, the functional groups of the amino acid side chains remain conveniently protected with temporary or permanent protecting groups and can be deprotected simultaneously or orthogonally to the process of cleavage of the peptide from the polymer support.

[0051] Alternatively, solid phase synthesis can be performed using a convergent strategy: coupling the peptide to a polymer support or coupling to a peptide or amino acid pre-bound to a polymer support. Convergent synthesis strategies are widely known to those skilled in the art and are described in Lloyd-Williams P. et al., "Convergent Solid-Phase Peptide Synthesis", (1993), Tetrahedron, 49 (48), 11065-11133.

[0052] Under the circumstances of using the standard procedures and conditions known in the prior art, the process of the present invention can include in no particular order additional stages of C-terminal deprotection and / or cleavage of the peptide from the polymer support; after which these terminal functional groups can be modified. The optional modification of the C-terminus can be carried out when the polypeptide compound represented by formula (I) is fixed to the polymer support or once the polypeptide compound has been separated from the polymer support.

[0053] A person skilled in the art will readily appreciate that the deprotection / cleavage steps of the C-terminus and the N-terminus and their subsequent derivatization can be performed in different orders according to procedures known in the art.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The antimicrobial peptide provided by the present invention is based on the structure of natural antimicrobial peptides, and the amino acids therein are replaced with amino acids of similar properties and a small amount of modifiable functional amino acids, and then the functional amino acids are connected by chemical means to form a cyclic peptide, thereby obtaining a new antimicrobial peptide, which has the same level of antimicrobial activity as the prototype antimicrobial peptide, and the stability of the antimicrobial peptide is improved by cyclization. The antimicrobial cyclic peptide of the present invention improves the stability of the antimicrobial peptide while maintaining or improving the antimicrobial activity of the natural antimicrobial cyclic peptide, and can be widely used in the preparation of antimicrobial drugs and widely used. DETAILED DESCRIPTION

[0056] In order to further illustrate the present invention, the polypeptide compound and application thereof provided by the present invention are described in detail below in conjunction with examples.

[0057] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0058] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0059] Example 1-78: Preparation of Compound 1-78

[0060] The peptide synthesis was carried out using the standard Fmoc solid phase method, using Rink Amide resin, and the peptide chain was extended from the C-terminus to the N-terminus.

[0061] The protected amino acids include: Fmoc-Ala-OH, Fmoc-Leu-OH, Fmoc-Ile-OH, Fmoc-Phe-OH, Fmoc-Pro-OH, Fmoc-Trp(Boc)-OH, Fmoc-Val-OH, Fmoc-Met-OH, Fmoc-Lys(Boc)-OH, Fmoc-Arg(Pbf)-OH, Fmoc-His(Boc)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Hcy(Trt)-OH, Fmoc-Pen(Trt)-OH, Fmoc-α-Me-Gly(Pentenyl)-OH. The condensation agent is HBTU / HOBt / DIEA. The deprotection reagent is piperidine / DMF solution. The crude peptide is dissolved in water and then freeze-dried for storage. It is separated and purified by medium pressure liquid chromatography or high performance liquid chromatography (HPLC), and the pure peptide content is greater than 85%. Matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) was used to determine the molecular weight of the peptide sequence. The purified linear peptide was cross-linked with a cross-linking agent in the presence of an activated base to form a ring, and the cross-linking agent included m-dibromobenzyl, o-dibromobenzyl, p-dibromobenzyl or succinimide; the linear peptide containing Fmoc-α-Me-Gly(Pentenyl)-OH, the reaction solution after ring formation was separated and purified by medium pressure liquid chromatography or high performance liquid chromatography (HPLC), and the pure peptide content was greater than 90%.

[0062] Synthesis of peptide sequences:

[0063] The synthesis conditions are as follows:

[0064] Protected amino acid (natural or unnatural): 2M DMF solution,

[0065] Condensation agent: 3M HBTU / HOBt in DMF solution,

[0066] Activating base: 2M DIEA in DMF,

[0067] Deprotection reagent: 20% v / v piperidine in DMF,

[0068] Cross-linker activation base solution: a solution of 6 times the equivalent of the cross-linker (m-dibrombenzyl, o-dibrombenzyl, p-dibrombenzyl or dibromosuccinimide) of the purified linear peptide and DIEA in acetonitrile / water (volume ratio 1:1).

[0069] Step 1: Using amide resin, Fmoc protected amino acid, coupling reagent and organic base as starting materials, react in a protected organic solvent to obtain Fmoc protected amino acid-amide resin coupling product.

[0070] Step 2: Use the solid phase method to couple amino acids with protective groups one by one to synthesize a linear peptide with fully protected side chains.

[0071] Step 2.1: Deprotection: Weigh 2.3 g (1 mmol) of Rink Amide resin and place it in a peptide synthesis reactor. Then prepare the deprotection reagent according to the above concentration and add it to the resin. React at room temperature, drain, add piperidine / DMF again, react at room temperature, drain, and wash with DMF until it passes the test.

[0072] Step 2.2: Condensation reaction: add amino acid and condensation agent to DMF for activation under ice bath condition, then add activation base to obtain activation solution, finally add activation solution to resin, react at room temperature, use 5% ninhydrin colorimetric reagent to color the resin, drain the solvent and wash with DMF, drain the solvent after qualified detection, at this time the condensation reaction is complete.

[0073] The above deprotection and condensation reactions are repeated until the peptide chain synthesis is completed to obtain a peptide resin containing a complete polypeptide sequence structure.

[0074] Step 3: Add a shearing agent to shear the linear peptide from the resin, freeze-dry in vacuum to obtain a crude polypeptide, and then purify it using preparative liquid chromatography.

[0075] Step 3.1: Cleavage of peptide resin: Weigh 7g of the synthesized peptide resin, put it into a 250mL eggplant-shaped bottle, ice bath, and electromagnetic stirring. Prepare cleavage solution by adding 10mL of 1g peptide resin [cleavage solution (volume percentage): trifluoroacetic acid: triisopropylsilane: ethanedithiol: water = 92.5:2.5:2.5:2.5]. TFA needs to be cooled in an ice bath for 30min or stored in a refrigerator before use; add the prepared cleavage solution to the peptide resin under ice bath conditions, electromagnetic stirring, react under ice bath conditions for 30min, then remove the ice bath, and continue stirring and reacting at room temperature for 180min. After the reaction is completed, filter the reaction solution with a G4 sand core funnel, concentrate it by rotary evaporation, and then add ice methyl tert-butyl ether at a volume ratio of 1:10 to precipitate a white precipitate, centrifuge for 10min (5000 rpm), remove the supernatant, take the precipitated solid, add 50mL of double distilled water to dissolve, and freeze-dry to obtain 1.23g of crude peptide.

[0076] Step 3.2: Purification of crude linear peptides: The crude peptides are purified by medium pressure or high performance liquid chromatography. The chromatographic column is a C18 column, and the eluent is acetonitrile, water and a small amount of trifluoroacetic acid. Specific operation steps: weigh 1.00g of crude peptide, add 20mL of water and 5mL of acetonitrile to dissolve the solid, centrifuge for 10min (5000 rpm), and take the supernatant for sample loading. The chromatographic column is pre-equilibrated with 200mL of 5% acetonitrile / water / 0.1% trifluoroacetic acid solution. After loading, continue to rinse with 200mL of 5% acetonitrile / water / 0.1% trifluoroacetic acid solution, and detect the components of the eluent by high performance liquid chromatography. According to the results of liquid phase detection, the acetonitrile content is gradually increased until the main peak of the purified polypeptide is eluted. Combine the eluents, remove most of the solvent by rotary evaporation, freeze-dry the pure polypeptide, HPLC detection content is greater than 85%, and MALDI-TOF-MS confirms the molecular weight.

[0077] Step 4: The crude cyclic peptide is obtained by binding the linear peptide, the cross-linking agent and the organic base in the liquid phase, and is directly purified by preparative liquid chromatography: 0.1g of the linear peptide is stirred and reacted with the cross-linking agent in 10mL of the activated base solution at room temperature for 240min-24h. After the reaction is completed, 20mL of double distilled water is added and the sample is loaded. The chromatographic column is pre-equilibrated with 200mL of 5% acetonitrile / water / 0.1% trifluoroacetic acid solution. After loading, continue to rinse with 200mL of 5% acetonitrile / water / 0.1% trifluoroacetic acid solution, and the components of the eluent are detected by high-performance liquid chromatography. According to the results of the liquid phase detection, the acetonitrile content is gradually increased until the main peak of the purified polypeptide is eluted. The eluents are combined, most of the solvent is removed by rotary evaporation, and the pure polypeptide is lyophilized. The HPLC detection content is greater than 90%, and the molecular weight is confirmed by MALDI-TOF-MS.

[0078] The prepared antibacterial cyclic peptide compounds are shown in Table 1.

[0079] Table 1 List of synthetic antibacterial cyclic peptide compounds

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092] Example 79: Antimicrobial Cyclic Peptides in vitro Bacterial Drug Susceptibility Test (MIC 50 )

[0093] The screening of antimicrobial cyclic peptides is completed through in vitro bacterial drug sensitivity tests. The antibacterial effect of antimicrobial cyclic peptides can be evaluated by measuring the sensitivity or resistance level of bacteria to antimicrobial cyclic peptides in vitro.

[0094] 1. Experimental Procedure

[0095] 1.1 Test strains

[0096] The tested strains were methicillin-resistant Staphylococcus aureus MRSA, methicillin-sensitive Staphylococcus aureus MSSA, and methicillin-resistant Staphylococcus epidermidis MRSE. The quality control strain was Staphylococcus aureus ATCC 29213. The test strains were cultured in MHA medium at 35-37°C for 24 hours.

[0097] Preparation of bacterial solution: Each bacterial strain was purified by streaking a single colony on an agar plate before the test. After incubation at 35-37°C, a single colony was picked and the turbidimetric method was adjusted to about 0.5 McFarland units (about 10 8 CFU / ml). The suspension was diluted 100 times for the two-fold agar dilution method, and the diluted bacterial solution was inoculated on the prepared MH agar plate using a multi-point inoculator. The suspension was diluted 1000 times for the micro broth method.

[0098] 1.2 Test steps

[0099] Set the concentration of antimicrobial cyclopeptide to be diluted twice within the range of 0.008-128μg / ml. Add 1ml of antimicrobial cyclopeptide solution to a sterile plate, then add 14ml of melted 50℃ MHA medium and mix well. Make the final concentration of antimicrobial cyclopeptide in each plate 128, 64, 32, 16, 8, 4, 2, 1, 0.5, 0.25, 0.125, 0.06, 0.03, 0.015, 0.008μg / ml, in turn. After cooling, inoculate bacteria with a multi-point inoculator, cover the plate, use MHA medium, and culture at 35-37℃ for 24h. After the culture is completed, observe with the naked eye. The lowest sample concentration at which no bacterial growth is seen in the plate is its minimum inhibitory concentration (MIC). At the same time, set up a bacterial control without any sample and a blank culture medium control.

[0100] According to the above method, the results of in vitro bacterial drug sensitivity test are shown in Table 2.

[0101] Table 2 Minimum inhibitory concentration (MIC) of antimicrobial cyclic peptides against three bacteria 50 (μg / ml)

[0102]

[0103]

[0104]

[0105] From the results in Table 2, it can be seen that in the preparation of the present invention, a variety of antibacterial cyclic peptides showed in vitro antibacterial activity, and even the MIC of some antibacterial cyclic peptides was 50 Reached 16, 8 or even 4.

[0106] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. An antibacterial cyclic peptide, characterized in that Its amino acid sequence is shown in formula (I): H-Ile-Xaa2-Xaa3-Xaa4-Xaa5-Xaa6-Xaa7-Xaa8-Xaa9-Xaa 10 -Xaa 11 -Arg-Arg-NH2 Formula (I) in: Xaa2 is selected from Leu, Cys, Hcy, Pen or S5 amino acids; Xaa3 is selected from Pro, Cys, Hcy, Pen or S5 amino acids; Xaa4 is selected from Trp, Cys, Hcy, Pen or S5 amino acids; Xaa5 is selected from Lys, Cys, Hcy, Pen or S5 amino acids; Xaa6 is selected from Trp, Cys, Hcy, Pen or S5 amino acids; Xaa7 is selected from Pro, Cys, Hcy, Pen or S5 amino acids; Xaa8 is selected from Trp, Cys, Hcy, Pen or S5 amino acids; Xaa9 is selected from Trp, Cys, Hcy, Pen or S5 amino acids; XA 10 Selected from Pro, Cys, Hcy, Pen or S5 amino acids; XA 11 Selected from Trp, Cys, Hcy, Pen or S5 amino acids; in, There are only two amino acids selected from Cys, Hcy, Pen or S5 amino acids; The S5 amino acid is: α-Me-Gly(Pentenyl)-OH, Furthermore, when any amino acid at position i among Xaa2 to Xaa7 is replaced by Cys, Hcy, Pen or S5, 11 Another amino acid at position i+4 is simultaneously replaced with the same Cys, Hcy, Pen or S5 amino acid, and i and the amino acid at position i+4 are cross-linked to form a cyclic peptide, wherein the value of i is 2-7, including both ends.

2. An antibacterial cyclic peptide according to claim 1, characterized in that: Xaa4 and Xaa8 are simultaneously replaced with the same Cys, Hcy, Pen or S5 amino acid, and cross-linked at this position to form a cyclic peptide.

3. An antibacterial cyclic peptide according to claim 1, characterized in that: Xaa7 and Xaa 11 At the same time, they are replaced by the same Cys, Hcy, Pen or S5 amino acid and cross-linked at this position to form a cyclic peptide.

4. An antibacterial cyclic peptide according to any one of claims 1 to 3, characterized in that: When the amino acids at positions i and i+4 are selected from one of Cys, Hcy or Pen, the amino acids at positions i and i+4 are connected via a cross-linking agent to form a cyclic peptide.

5. An antibacterial cyclic peptide according to claim 4, characterized in that: The crosslinking agent is selected from one or more of m-dibrombenzyl, o-dibrombenzyl, p-dibrombenzyl or succinimide.

6. An antibacterial cyclic peptide according to any one of claims 1 to 3, characterized in that: When the amino acids at positions i and i+4 are S5 amino acids, the amino acids at positions i and i+4 are directly connected to form a cyclic peptide.

7. An antibacterial cyclic peptide according to claim 1, characterized in that: The antibacterial cyclic peptide is shown in sequences SEQ ID No. 1 to SEQ ID No.

78.

8. A method for preparing an antibacterial cyclic peptide according to any one of claims 1 to 7, characterized in that: The steps include: Step 1: Using amide resin, Fmoc protected amino acid, coupling reagent and organic base as starting materials, react in a protected organic solvent to obtain Fmoc protected amino acid-amide resin coupling product; Step 2: Use the solid phase method to couple amino acids with protective groups one by one to synthesize a linear peptide with fully protected side chains; Step 3: Add a shearing agent to shear the linear peptide from the resin, freeze-dry under vacuum to obtain a crude peptide, and then purify it using preparative liquid chromatography; Step 4: The crude cyclic peptide is obtained by binding the linear peptide, the cross-linking agent and the organic base in the liquid phase, and is directly purified by preparative liquid chromatography.

9. A composition, characterized in that The invention comprises an acceptable adjuvant and the antibacterial cyclic peptide according to any one of claims 1 to 7 or a pharmaceutically acceptable salt, ester or solvate thereof.

10. Use of the antimicrobial cyclic peptide or its pharmaceutically acceptable salt, ester, solvate and pharmaceutical composition thereof as claimed in any one of claims 1 to 7 in the preparation of a medicament for controlling or preventing microbial infection, wherein the indications of the microbial infection include wound infection, acne, diabetic foot ulcer, athlete's foot, onychomycosis, tinea, furuncle, impetigo, cellulitis, staphylococcal scalded skin syndrome, septic arthritis and bacteremia.

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