Cyclization of antimicrobial peptide CycP-1 targeting multi-drug resistant klebsiella pneumoniae, composition and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 湖北江夏实验室
- Filing Date
- 2026-04-15
- Publication Date
- 2026-07-24
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biomedical technology, specifically relating to a cyclized antimicrobial peptide CycP-1 targeting multidrug-resistant Klebsiella pneumoniae, its composition and application, especially its use in combination with antibiotics to enhance antibacterial effects, reverse drug resistance and delay the development of drug resistance. Background Technology
[0002] Klebsiella pneumoniae, especially carbapenem-resistant strains (CRKP), has become a major pathogen causing hospital-acquired infections worldwide. While existing antibiotics such as polymyxin are effective, they are highly nephrotoxic and exhibit increasing resistance, necessitating novel antibacterial strategies.
[0003] Antimicrobial peptides have attracted much attention due to their broad-spectrum antimicrobial activity and low tendency to induce drug resistance. However, their poor in vivo stability and susceptibility to protease hydrolysis are key issues limiting their application. This invention significantly improves the stability and antimicrobial activity of a cyclized antimicrobial peptide (CycP-1) with intramolecular disulfide bonds, and for the first time discovers that its combination with antibiotics can reverse drug resistance and delay the development of resistance. Summary of the Invention
[0004] This invention provides a group of cyclized antimicrobial peptides CycP-1 with intramolecular disulfide bonds, wherein the antimicrobial peptide is formed by cyclizing the first and 24th amino acids of SEQ ID NO.1 through disulfide bonds.
[0005] Another object of the present invention is to provide the application of the cyclized antimicrobial peptide CycP-1.
[0006] To achieve the above objectives, the present invention adopts the following technical measures:
[0007] Obtaining the cyclized antimicrobial peptide CycP-1:
[0008] The linear peptide shown in SEQ ID NO.1 was synthesized. The linear peptide was dissolved in 0.1 M ammonium acetate buffer (pH 8.0) and stirred slowly at room temperature for 24-48 hours to oxidize the thiol groups of the cysteine residues at positions 1 and 24, forming intramolecular disulfide bonds, thus obtaining the target antimicrobial peptide CycP-1 in a cyclized conformation.
[0009] The scope of protection of this invention also includes:
[0010] Application of cyclized antimicrobial peptide CycP-1 in delaying the development of antibiotic resistance in Klebsiella pneumoniae.
[0011] A mixed agent comprising the cyclized antimicrobial peptide CycP-1.
[0012] The above-mentioned mixed agents also include antibiotics.
[0013] In the above-described mixed agent, the mass ratio of the cyclized antimicrobial peptide CycP-1 to the antibiotic is 10:1 to 1:10.
[0014] Preferably, the antibiotics in the above-described mixed agents include at least one of β-lactams, tetracyclines, aminoglycosides, quinolones, sulfonamides, chloramphenicols, macrolides, and / or polymyxins.
[0015] More specifically, the antibiotics mentioned above include at least one of piperacillin, cefotaxime, ceftriaxone, tetracycline, amikacin, ofloxacin, norfloxacin, sulfamethoxazole / trimethoprim, gentamicin, ciprofloxacin, polymyxin B, chloramphenicol, streptomycin, florfenicol, and / or spectinomycin.
[0016] The above-mentioned mixed drugs include all dosage forms involved in the prior art, including oral dosage forms, injectable dosage forms, external dosage forms, respiratory dosage forms, ocular, ear or nasal dosage forms, implants, films, sustained-release, controlled-release dosage forms or targeted formulations.
[0017] The above-mentioned mixed medicine is preferably in the form of an oral powder or a topical gel.
[0018] The above-described mixed pharmaceutical preparation, preferably in powder form, includes excipients including maltodextrin, sucrose, and β-cyclodextrin.
[0019] The above-described mixed pharmaceutical preparation, preferably in the form of a gel, includes the following excipients: ciprofloxacin, carbomer 940, glycerin, methylparaben, and triethanolamine.
[0020] Application of cyclized antimicrobial peptide CycP-1 or the above-mentioned mixture in the preparation of Klebsiella pneumoniae inhibitors.
[0021] The use of cyclized antimicrobial peptide CycP-1 or the above-mentioned mixtures in the preparation of drugs for the treatment or prevention of Klebsiella pneumoniae infection.
[0022] The Klebsiella pneumoniae mentioned above includes multidrug-resistant and / or pan-drug-resistant Klebsiella pneumoniae.
[0023] The above-described applications refer to diseases caused by Klebsiella pneumoniae infection, including but not limited to pneumonia, bloodstream infections, urinary tract infections, wound infections, and animal diarrhea.
[0024] Compared with the prior art, the cyclized antimicrobial peptide of the present invention has the following beneficial effects:
[0025] 1. Strong anti-drug resistance: It has significant antibacterial activity against multidrug-resistant and extensively drug-resistant Klebsiella pneumoniae;
[0026] 2. Synergistic effect: When used in combination with multiple antibiotics, it can enhance the antibacterial effect and reverse or reduce drug resistance;
[0027] 3. Delaying drug resistance: When used in combination with antibiotics, it can significantly slow down the development of bacterial resistance.
[0028] 4. Significant in vivo efficacy: Mouse pneumonia model experiments have confirmed that oral administration of the cyclized antimicrobial peptide CycP-1 has a significant therapeutic effect on pan-drug-resistant Klebsiella pneumoniae infection, which can reduce the bacterial load in lung tissue, alleviate pathological damage, and improve survival rate. Furthermore, the efficacy can be further enhanced when used in combination with polymyxin B. Detailed Implementation
[0029] To enable those skilled in the art to better understand the technical content of this invention, the invention will be further described below with reference to specific embodiments and appendices. Unless otherwise specified, the technical solutions described in this invention are conventional solutions in the art; the reagents or materials described, unless otherwise specified, are all from commercial sources.
[0030] Example 1:
[0031] Chemical Synthesis and Cyclization of CycP-1, an Antimicrobial Peptide
[0032] A linear peptide with the amino acid sequence shown in SEQ ID NO. 1 was synthesized using the Fmoc solid-phase synthesis method. This sequence contains 25 amino acids, with cysteine residues at positions 1 and 24. After synthesis, the crude linear peptide was dissolved in 0.1 M ammonium acetate buffer (pH 8.0) and slowly stirred at room temperature for 24-48 hours. This oxidized the thiol groups of the cysteine residues at positions 1 and 24, forming intramolecular disulfide bonds, yielding the cyclized antimicrobial peptide CycP-1. The cyclized product was purified by RP-HPLC, and its retention time was slightly earlier than that of the linear precursor. MALDI-TOF MS (CHCA matrix) analysis showed that the measured molecular weight of the cyclized linear peptide shown in SEQ ID NO. 1 decreased by 2 Da compared to the theoretical linear value, confirming disulfide bond formation. The final product was a white powder with a purity >95%, used in the following examples.
[0033] Example 2:
[0034] In vitro antimicrobial activity of cyclized antimicrobial peptide CycP-1 against multidrug-resistant Klebsiella pneumoniae
[0035] Strains: Klebsiella pneumoniae standard sensitive strain ATCC 13883, standard drug-resistant strain ATCC 700603 (producing ESBLs), and 7 clinically isolated multidrug-resistant strains (KP177, KP178, KP298, KP310, KP344, KP385, KP415). Among them, KP298 is a pan-drug-resistant strain, resistant to all tested antibiotics, including β-lactams, quinolones, aminoglycosides, sulfonamides, and peptides. The other strains showed varying degrees of resistance to multiple antibiotics, as detailed in Table 1.
[0036] Methods: The Kirby-Bauer agar diffusion method was used. Overnight cultures of each strain were adjusted to 0.5 McFarland turbidity with physiological saline and evenly spread onto Mueller-Hinton (MH) agar plates. Wells were punched in the plates using a sterile punch (6 mm diameter), and 60 μL of a 512 μg / mL cyclic antimicrobial peptide CycP-1 solution was added to each well. Several commonly used clinical antibiotics (prepared according to CLSI standards, concentrations as in routine drug susceptibility testing) and sterile water were used as controls. After incubation at 37°C for 16-18 hours, the diameter of the inhibition zone was measured. The results are shown in Table 1.
[0037] Results analysis: As shown in Table 1, the cyclized antimicrobial peptide CycP-1 exhibited significant antibacterial activity against all tested strains (inhibition zone diameter 2.8-3.6 cm), and its effect was superior to most tested antibiotics. In particular, CycP-1 maintained strong activity against the standard strain ATCC 700603, which was completely resistant to multiple antibiotics (such as ceftriaxone and piperacillin), and several clinically resistant strains.
[0038] Table 1. Diameter of inhibition zones (mm) of cyclized antimicrobial peptide CycP-1 and various antibiotics against Klebsiella pneumoniae.
[0039] .
[0040] Note: The inhibition zone is determined according to the CLSI M02-A12 standard (resistant ≤12 mm; intermediate 13-22 mm; sensitive ≥23 mm).
[0041] Example 3:
[0042] Determination of the minimum inhibitory concentration (MIC) of cyclized antimicrobial peptide CycP-1 and its synergistic effect with antibiotics
[0043] Strains were selected for combined drug susceptibility testing: the standard sensitive strain ATCC 13883, the standard drug-resistant strain ATCC 700603, and the clinically highly drug-resistant strain KP298 (mentioned in Example 2 above) were selected.
[0044] Representative antibiotics from five classes—β-lactams (ceftriaxone), quinolones (ciprofloxacin), aminoglycosides (amikacin), sulfonamides (trimethoprim-sulfamethoxazole), and polypeptides (polymyxin B)—were selected for a combined antibacterial assay. Experimental methods: The fractional inhibitory concentration (FICI) of the combined drug was determined using the checkerboard microbroth dilution method. The minimum inhibitory concentration (MIC) of the cyclic antimicrobial peptide CycP-1 and the selected antibiotic against the target strain was determined according to CLSI M07-A10 standards. In 96-well plates, the cyclic antimicrobial peptide CycP-1 and the antibiotic were serially diluted 2-fold to achieve cross-combinations of concentrations between 1 / 4 MIC and 4 MIC. Bacterial culture (final concentration approximately 5 × 10^5 CFU / mL) was added to each well, and the plates were incubated at 37°C for 18–24 hours. Bacterial growth in each well was observed and recorded, the MICs of each drug in the combined drug regimen were determined, and the FICI values were calculated. FICI ≤ 0.5 is considered a synergistic effect, 0.5 < FICI ≤ 1 is an additive effect, 1 < FICI ≤ 2 is an irrelevant effect, and FICI > 2 is an antagonistic effect.
[0045] Results Analysis: The MICs of cyclized antimicrobial peptides and antibiotics used alone against target strains are shown in Table 2. The results of their combination use are shown in Table 3. The results show that cyclized antimicrobial peptide CycP-1, when used in combination with various antibiotics, exhibits good sensitizing or synergistic effects on the tested strains. For the standard drug-resistant strain ATCC 700603, the combination of cyclized antimicrobial peptide CycP-1 and ceftriaxone reduced the latter's MIC from 32 μg / mL to 2 μg / mL (FICI = 0.188), demonstrating a strong synergistic effect; when combined with polymyxin B, it reduced the MIC from 4 μg / mL to 0.5 μg / mL (FICI = 0.375). For the clinically highly drug-resistant KP-298 strain, the combination of cyclized antimicrobial peptide CycP-1 and polymyxin B still showed a strong synergistic effect (FICI = 0.375). These results indicate that the cyclized antimicrobial peptide CycP-1 can significantly enhance the in vitro antimicrobial activity of antibiotics (including antibiotics resistant to certain strains) and has the potential to reverse resistance.
[0046] Table 2. Antibacterial effects of cyclized antimicrobial peptide CycP-1 and antibiotics (checkerboard method)
[0047] .
[0048] Table 3 Synergistic antimicrobial effect of cyclized antimicrobial peptide CycP-1 in combination with antibiotics against Klebsiella pneumoniae (checkerboard method)
[0049] .
[0050] Example 4:
[0051] CycP-1, a cyclic antimicrobial peptide, delays the development of antibiotic resistance in bacteria.
[0052] Experimental method: The multi-generation subinhibitory concentration subculturing method was used.
[0053] Using the standard drug-resistant strain of Klebsiella pneumoniae ATCC 700603 as the research object, polymyxin B was selected as the representative antibiotic. Three groups were set up: Group A (polymyxin B alone), Group B (cyclized antimicrobial peptide CycP-1 alone), and Group C (polymyxin B + cyclized antimicrobial peptide (CycP-1) combination, mass ratio 1:4). The bacteria were passaged daily into fresh MH broth containing a subinhibitory concentration (1 / 2 MIC) of the drug (in Group C, the concentration of polymyxin B in fresh MH broth was 1 μg / mL, and the concentration of cyclized antimicrobial peptide (CycP-1) was 4 μg / mL), for 30 consecutive days. The changes in the MIC of the bacteria against polymyxin B and cyclized antimicrobial peptide (CycP-1) were measured every 5 generations.
[0054] Results: After 30 passages, the results are shown in Table 4. In Group A (polymyxin B alone), the MIC value of bacteria increased dramatically from an initial 2 μg / mL to 128 μg / mL, a 32-fold increase, indicating that the bacteria rapidly developed high-level resistance under single antibiotic pressure. In Group B (cyclized antimicrobial peptide CycP-1 alone), the MIC value of bacteria increased only from 2 μg / mL to 8 μg / mL, a 4-fold increase, indicating that CycP-1 itself is not easily induced to induce resistance. In Group C (combined therapy), the MIC value of bacteria against polymyxin B increased only from 2 μg / mL to 8 μg / mL (a 4-fold increase), and the rate of increase slowed significantly throughout the passages. The final MIC value was much lower than that of the single-drug group, indicating that CycP-1 can effectively delay the development of polymyxin B resistance.
[0055] Table 4. Results of passage experiments showing the effect of combined use of cyclized antimicrobial peptide (CycP-1) and polymyxin B on the MIC value of polymyxin B.
[0056] .
[0057] Example 5:
[0058] Application of antimicrobial peptide CycP-1 in the preparation of drugs for treating Klebsiella pneumoniae infection in mice
[0059] 1. Preparation of spray-dried oral powder of antimicrobial peptide CycP-1:
[0060] The mass percentages of the components in the protective agent solution are: 76% maltodextrin, 16% sucrose, and 8% β-cyclodextrin, with water as the solvent.
[0061] Mixing solution: Mix the cyclized antimicrobial peptide CycP-1 solution (concentration 10 mg / mL) with the above-mentioned protective agent solution, controlling the mass ratio of cyclized antimicrobial peptide CycP-1 to the total dry weight of the protective agent to be 1:10. Stir thoroughly and mix evenly at room temperature (<35℃).
[0062] Homogenization: The mixed liquid is homogenized by a high-pressure homogenizer at a pressure of 20-50 MPa to form a stable emulsified dispersion system.
[0063] Spray drying: The homogenized liquid material is spray dried. Key process parameters are: inlet air temperature 145℃, outlet air temperature strictly controlled between 75-85℃, and atomizer speed or pressure adjusted according to the equipment to obtain uniform droplets.
[0064] Post-processing: The dried powder is collected immediately, and fumed silica is added to the powder to achieve a final mass concentration of 2%. The powder is then thoroughly dry-mixed using a mixer to improve its flowability and anti-caking properties.
[0065] Quality control: The obtained powder is an off-white, free-flowing powder.
[0066] 2. Determination of Active Peptide Content in CycP-1 Spray-Dried Powder (a CycP-1 Antimicrobial Peptide)
[0067] (1) Chromatographic conditions: Column C18 (4.6×250 mm, 5 μm); Mobile phase A is 0.1% trifluoroacetic acid (TFA) aqueous solution, and mobile phase B is 0.1% TFA acetonitrile solution; Elution gradient: 0~5 min, 95% A; 5~20 min, 95%→40% A; 20~25 min, 40%→5% A; 25~30 min, 5% A; 30~32 min, 5%→95% A; 32~40 min, 95% A; Flow rate 1.0 mL / min; Detection wavelength 214 nm; Column temperature 30℃; Injection volume 20 μL.
[0068] (2) Preparation of reference solution: Accurately weigh CycP-1 reference standard, dissolve it in 0.1% TFA aqueous solution to prepare 0.5 mg / mL stock solution, dilute to a series of concentrations (0.01~0.5 mg / mL), and filter through a 0.22 μm filter membrane.
[0069] (3) Preparation of test solution: Accurately weigh about 0.1 g of powder (record mass W, g), add 20 mL of 0.1% TFA aqueous solution, vortex for 5 min, sonicate for 20 min, transfer to a 25 mL volumetric flask and make up to volume, centrifuge and filter.
[0070] (4) Determination and calculation: Inject the reference solution and plot a standard curve using peak area against concentration. Inject the test solution, record the peak area, and substitute it into the standard curve to calculate the concentration C (mg / mL). Measured content of active peptide in powder (mg / g) = C × 25 / W.
[0071] (5) Calculation of active peptide recovery rate: Let the total mass of active peptides fed be M. input (mg), total mass of powder after drying M powder The content is (g), and the actual measured content is C. measured (mg / g), then the recovery rate (%) = (C measured × M powder / M input ) ×100%.
[0072] Table 5 Physicochemical properties and activity recovery rate of spray-dried powder (n=3)
[0073] .
[0074] Note: SD stands for standard deviation.
[0075] 3. In vivo therapeutic effect of spray-dried oral powder of antimicrobial peptide CycP-1 on Klebsiella pneumoniae infection in mice.
[0076] 1). Experimental Materials
[0077] Test drug: spray-dried oral powder containing cyclized antimicrobial peptide CycP-1 prepared in step 1; control drug: polymyxin B sulfate; blank excipient powder (i.e., spray-dried oral powder without the active ingredient cyclized antimicrobial peptide CycP-1).
[0078] Experimental strain: Klebsiella pneumoniae clinically resistant strain KP-298 (MIC determined by MIC: MIC = 8 μg / mL against polymyxin B; MIC = 4 μg / mL against cyclized antimicrobial peptide CycP-1).
[0079] Laboratory animals: SPF-grade BALB / c mice, female, 6-8 weeks old, weighing 18-22 g. They were housed in an SPF-grade animal facility with free access to food and water, and were used in experiments after 7 days of acclimatization.
[0080] 2). Experimental Methods
[0081] 2.1 Establishment of a mouse pneumonia model
[0082] Klebsiella pneumoniae KP-298 was inoculated into MH broth and cultured at 37°C with shaking until the logarithmic growth phase. The bacterial cells were collected by centrifugation, washed with sterile physiological saline, and the concentration was adjusted to 5 × 10⁻⁶. 8CFU / mL. Mice were anesthetized by intraperitoneal injection of sodium pentobarbital (50 mg / kg), fixed in a supine position, and 50 μL of bacterial suspension (approximately 2.5 × 10⁻⁶ CFU / mL) was slowly injected through the trachea using a microsyringe. 7 (CFU / animal) to establish an acute pneumonia model.
[0083] 2.2 Experimental grouping and dosing regimen
[0084] Sixty mice were randomly divided into six groups of ten each. The experimental procedure is shown in Table 6. The volume of drug administered via gavage was determined based on the mouse's body weight (20 g) and the tolerated dose of conventional oral administration (0.1 mL / 10 g body weight), with each 20 g mouse receiving 0.2 mL via gavage. The volume of drug administered via intraperitoneal injection was determined based on the mouse's body weight and the conventional intraperitoneal injection volume (0.05–0.1 mL / 10 g body weight), with each 20 g mouse receiving 0.1 mL via intraperitoneal injection. The blank control group received sterile saline at a volume of 0.2 mL per mouse. All drug solutions or suspensions were prepared to the target concentration using the appropriate solvent (physiological saline) to ensure the administration volume met the above requirements.
[0085] Table 6 Experimental Groups and Drug Administration
[0086] .
[0087] 2.3 Observation Indicators
[0088] (1) Survival rate: After infection, mice were observed for 7 consecutive days, and the mortality of each group of mice was recorded and survival curves were plotted.
[0089] (2) Bacterial load in lung tissue: 24 h post-infection, 5 mice were randomly selected from each group and euthanized by cervical dislocation. The right lung tissue was aseptically harvested, weighed, and homogenized with sterile physiological saline. After 10-fold serial dilution, the tissue was spread on MH agar plates and incubated at 37°C for 24 h. Colony forming units (CFU) were counted, and the bacterial load per gram of lung tissue (log) was calculated. 10 CFU / g).
[0090] (3) Lung tissue pathological examination: 24 h after infection, 3 mice were randomly selected from each group, and the left lung tissue was taken, fixed in 10% neutral formalin, embedded in paraffin, sectioned, stained with HE, and the pathological changes were observed under a light microscope.
[0091] 3). Experimental Results
[0092] 3.1 Survival rate
[0093] Seven days after infection, all mice in the model group died, with a survival rate of 0%. The survival rate was 40% in the polymyxin B group, 50% in the low-dose CycP-1 group, and 70% in the high-dose CycP-1 group. The highest survival rate was 90% in the combination therapy group. The combination therapy group showed a highly significant difference compared to the model group (P < 0.01) and a significant difference compared to the polymyxin B monotherapy group (P < 0.05). These results indicate that oral administration of the cyclic antimicrobial peptide CycP-1 has a protective effect against infection with pan-drug-resistant Klebsiella pneumoniae, and its combination with polymyxin B significantly improves the efficacy.
[0094] 3.2 Bacterial load in lung tissue
[0095] The results of the lung tissue bacterial load measurement 24 h post-infection are shown in Table 7. The combined drug group had the lowest lung tissue bacterial load, which was about 4 orders of magnitude lower than the model group and about 2 orders of magnitude lower than the polymyxin B monotherapy group. The difference was statistically significant (P < 0.01).
[0096] Table 7. Bacterial load in lung tissue of mice 24 h after infection (log) 10 CFU / g, n=5, x̄±SD)
[0097] .
[0098] Note: Compared with the model group, *P < 0.05, **P < 0.01; compared with the polymyxin B group, #P < 0.05, ##P < 0.01.
[0099] 3.3 Pathological observation of lung tissue
[0100] HE staining results showed that the lung tissue of the model group mice showed extensive alveolar wall thickening, inflammatory cell infiltration, alveolar cavity exudation and hemorrhage, which were typical changes of severe pneumonia. The inflammatory response was reduced in the polymyxin B group and the low-dose CycP-1 group, but focal inflammatory infiltration was still visible. The alveolar structure of the high-dose CycP-1 group was relatively intact, and the inflammatory cell infiltration was significantly reduced. The lung tissue morphology of the combined drug group was close to normal, with only a small amount of inflammatory cell infiltration and the mildest pathological changes.
[0101] 4). Conclusion
[0102] This embodiment demonstrates, using a mouse pneumonia model, that the spray-dried oral powder containing the cyclized antimicrobial peptide CycP-1 has a significant therapeutic effect on lung infections caused by pan-drug-resistant Klebsiella pneumoniae KP-298, reducing bacterial load in lung tissue, alleviating lung pathological damage, and improving the survival rate of infected mice. Combined use with polymyxin B produces a synergistic effect, with efficacy superior to either drug alone. These results provide sufficient in vivo experimental evidence for the use of the pharmaceutical composition of this invention in treating infections (including pneumonia) caused by Klebsiella pneumoniae.
[0103] Example 6:
[0104] Preparation of topical gel containing cyclized antimicrobial peptide CycP-1 and ciprofloxacin
[0105] Formula: Ciprofloxacin 1.0% (w / w), CycP-1 cyclized antimicrobial peptide powder 1.0% (w / w), Carbomer 940 1.2%, Glycerin 5.0%, Methylparaben 0.1%, Triethanolamine as needed (to adjust pH to 6.0-7.0), the remainder being water.
[0106] Preparation process: Carbomer 940 was uniformly dispersed in a portion of purified water and allowed to swell overnight. Ciprofloxacin and the cyclized antimicrobial peptide CycP-1 were dissolved in the remaining water, and glycerol and methylparaben were added and mixed thoroughly. The drug solution was slowly added to the carbomer gel matrix under stirring, and the pH was adjusted with triethanolamine until a transparent gel formed. Purified water was added to the final volume, and the mixture was stirred until homogeneous. This gel is used to treat drug-resistant Klebsiella pneumoniae infection complicated by skin wounds.
[0107] The above embodiments fully demonstrate that the cyclic antimicrobial peptide CycP-1 (SEQ ID NO. 1) provided by this invention possesses highly efficient and broad-spectrum antimicrobial activity against multidrug-resistant Klebsiella pneumoniae, and its stability is significantly superior to that of linear peptides. When used in combination with existing antibiotics, this antimicrobial peptide produces a significant synergistic effect, effectively reversing or reducing bacterial resistance and delaying its development. In vivo animal experiments further confirm its great potential for treating infections caused by multidrug-resistant strains. Based on this, various pharmaceutical compositions (such as oral powders and topical gels) have been developed, showing promising industrialization prospects and clinical application value.
[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A synthetically produced cyclized antimicrobial peptide CycP-1, wherein the antimicrobial peptide is formed by cyclizing the first and 24th amino acids of SEQ ID NO.1 via disulfide bonds.
2. A mixed pharmaceutical agent, wherein the main active ingredient of the mixed pharmaceutical agent is the cyclized antimicrobial peptide CycP-1 as described in claim 1 and an antibiotic, wherein the antibiotic is at least one of β-lactam antibiotics, aminoglycosides, quinolones, sulfonamides and / or polymyxins.
3. The mixed agent according to claim 2, wherein the mass ratio of the cyclized antimicrobial peptide CycP-1 to the antibiotic is 10:1 to 1:
10.
4. The mixed agent according to claim 2, wherein the antibiotic is at least one selected from piperacillin, cefotaxime, ceftriaxone, amikacin, ofloxacin, norfloxacin, sulfamethoxazole / trimethoprim, gentamicin, ciprofloxacin, polymyxin B, streptomycin, florfenicol and / or spectinomycin.
5. The use of the cyclized antimicrobial peptide CycP-1 according to claim 1 in the preparation of a medicament for delaying the development of antibiotic resistance in Klebsiella pneumoniae.
6. The use of the cyclized antimicrobial peptide CycP-1 according to claim 1 or the mixed agent according to claim 3 in the preparation of a Klebsiella pneumoniae antibacterial agent.
7. The use of the cyclized antimicrobial peptide CycP-1 of claim 1 or the mixed agent of claim 3 in the preparation of a medicament for treating or preventing Klebsiella pneumoniae infection.
8. The application according to claim 5, 6 or 7, wherein the Klebsiella pneumoniae is a multidrug-resistant and / or pan-drug-resistant Klebsiella pneumoniae.