Antibacterial peptide UBI 29-41 derivative containing proline as well as preparation method and application of antibacterial peptide UBI 29-41 derivative

Abstract

The invention belongs to the technical field of radiopharmaceutical chemistry and clinical nuclear medicine, and particularly relates to an antibacterial peptide UBI 29-41 derivative containing proline as well as a preparation method and application thereof. The proline-containing antibacterial peptide UBI 29-41 derivative is labeled by radionuclide to obtain a radioactive preparation, and the radioactive preparation has high uptake in a bacterial infection part, has a good infection / non-target ratio, and can be specifically combined with bacteria. The radioactive preparation provided by the invention can be used as a novel radioactive drug for diagnosis of bacterial infection, and has good clinical popularization and application prospects and value.

Description

Technical Field

[0001] This invention relates to the fields of radiopharmaceuticals and nuclear medicine, specifically to a proline-containing antimicrobial peptide UBI 29-41 derivative, its preparation method, and its application. Background Technology

[0002] Globally, bacterial infections remain a pressing public health challenge. Multiple factors, including an aging population, widespread implantable surgeries, and rising antibiotic resistance, have contributed to a rapid increase in the number of patients with bacterial infections. Bacterial infections often progress rapidly, and failure to provide timely and accurate diagnosis and effective treatment can severely threaten a patient's life. Furthermore, overdiagnosis can lead to a series of problems: it may result in unnecessary medical procedures, such as the removal and re-implantation of implanted devices, prolong hospital stays, increase mortality rates, and impose a heavy social and healthcare burden. Therefore, achieving accurate and rapid diagnosis of bacterial infections and effectively differentiating them from aseptic inflammation is crucial for patient clinical management and treatment decision-making.

[0003] In recent years, nuclear medicine imaging technologies such as single-photon emission computed tomography (SPECT) and positron emission tomography (PET) have made significant progress. Nuclear medicine imaging can accurately locate lesion areas, intuitively reflect the pathophysiological changes at the site of infection, and help in the investigation of causes and the formulation of personalized treatment plans. It also has significant advantages such as high sensitivity and high specificity. 99m Tc is currently the most widely used SPECT imaging radionuclide in clinical practice. Its radionuclide properties are well-suited to clinical testing needs, and it can be used without the need for an accelerator. 99 Mo / 99m Tc generator rinsing equipment is readily available. Furthermore, 99m Tc-labeled drugs are easier to manufacture in kit form, making them more readily available for clinical application. Based on this, the development of novel... 99m Tc-labeled bacterial infection imaging agents have important clinical significance.

[0004] The antimicrobial peptide UBI 29-41 is a cationic peptide that can specifically bind to the negatively charged surface of bacteria, making it an important target and research hotspot in the development of imaging agents for bacterial infections. Recently, researchers have utilized... 99mTc-labeled derivatives of the antimicrobial peptide UBI29-41 (UBI(29-41)-2-APBA, N2S2-UBI 29-41, PN2S-PEG-UBI 29-41, HYNIC-UBI29-41, etc.) have achieved good imaging results for bacterial infections (Jiang Y, et al. Current Status of and Perspectives on Radiolabeled Ubiquicidin 29-41 Derivatives for Bacterial Infection Imaging. Mini-Rev Med Chem, 2023, 23(15), 1500-1506.). However, although some 99m The Tc-labeled antimicrobial peptide UBI 29-41 has shown some effectiveness in animal model experiments and clinical trials, but there is still room for optimization in this type of probe. For example, the structure is not yet clear and the uptake by non-target organs (kidney, muscle, blood, etc.) is too high, which need to be further addressed.

[0005] Linkers connect the target group and the chelating group attached to the radionuclide, playing a crucial role in regulating the target affinity and in vivo metabolism of radiopharmaceuticals. Studies have reported that introducing D-proline (D-Pro) into molecular probes can retain specific targeting uptake while effectively reducing its uptake in non-target organs (Ruan Q, et al. Synthesis and Evaluation of...). 99m Tc-Labeled FAP Inhibitors with DifferentLinkers for Imaging of Fibroblast Activation Proteins in Tumors.J Med Chem,2023,66(7),4952-4960; Feng J,et al.Synthesis and Preclinical Evaluation of Novel 99mTc-Labeled FR-Targeting Agents with Satisfactory Imaging Contrast and Reduced Renal Uptake. J Med Chem, 2025, 68(5), 5675-5686.). Based on this background, this invention uses proline as a linker to improve the pharmacokinetic properties of the complex, thereby reducing the uptake of this type of imaging agent by non-target organs such as the kidneys, thus reducing radiation damage to patients and improving imaging quality. Hydrazinenicotinamide (HYNIC) is... 99m Tc-labeled radiopharmaceuticals are commonly used bifunctional linkers. Based on this background, this invention synthesizes a proline and HYNIC-containing antimicrobial peptide derivative, UBI 29-41, and, with the participation of other co-ligands, further... 99m Using Tc labeling to explore novel radiopharmaceuticals that specifically target bacterial infections has significant scientific implications and broad clinical application prospects. Summary of the Invention

[0006] This invention provides a proline-containing antimicrobial peptide UBI 29-41 derivative, its preparation method, and its application. This derivative has good stability and is easy to prepare. After radiolabeling, it can be used for the diagnosis and treatment of bacterial infections. It exhibits high uptake in bacterial abscesses and a good target / non-target ratio, which has significant scientific value and application prospects in the field of bacterial infection diagnosis.

[0007] Specifically, the present invention provides the following technical solutions:

[0008] An antimicrobial peptide UBI 29-41 containing proline, its preparation method, and its application, wherein the structural formula is (I):

[0009] The corresponding derivative prepared from this derivative 99m Tc complexes specifically bind to bacterial surfaces, exhibiting very low uptake in non-target organs, high uptake values ​​for bacterial infections and abscesses, and high abscess / blood and abscess / muscle ratios, thus achieving excellent results in the diagnosis and treatment of bacterial infections.

[0010] The present invention also provides a radioactive preparation comprising the above-mentioned proline-containing antimicrobial peptide UBI 29-41 derivative labeled with a radionuclide, a preparation method thereof, and its application.

[0011] Preferably, in the above-mentioned radioactive preparation, the radionuclide portion is a metallic radionuclide.

[0012] Preferably, in the above-mentioned radioactive agents, the metallic radionuclide is...99m Tc, 99 Tc, 94m Tc, 94 Tc, 52 Mn, 186 Re or 188 Re.

[0013] Most preferably, in the above-mentioned radioactive preparation, the radionuclide is... 99m Tc, the structural formula of the radioactive agent is (II):

[0014]

[0015]

[0016] In the formula: M is 99m Tc forms a stable state 99m The coligand components of Tc complexes are N-tris(hydroxymethyl)methylglycine (Tricine) and ethylenediamine-N,N'-diacetic acid (EDDA), N-tris(hydroxymethyl)methylglycine (Tricine) and sodium triphenylphosphine tri-m-sulfonate (TPPTS), N-tris(hydroxymethyl)methylglycine (Tricine) and sodium diphenylphosphine-3-sulfonate (TPPMS), N-tris(hydroxymethyl)methylglycine (Tricine) and 2-(pyridin-4-yl)acetic acid (PA), N-tris(hydroxymethyl)methylglycine (Tricine) and nicotinic acid (NIC), N-tris(hydroxymethyl)methylglycine (Tricine) and isonicotinic acid (ISONIC), N-tris(hydroxymethyl)methylglycine (Tricine) and 3,5-pyridinedicarboxylic acid (PDA), and N-tris(hydroxymethyl)methylglycine (Tricine) and 3-pyridinesulfonic acid (PSA).

[0017] The present invention also provides the application of the above-mentioned radioactive agents in the field of bacterial infection diagnosis.

[0018] The beneficial effects of this invention are as follows: This invention provides a proline-containing antimicrobial peptide UBI 29-41 derivative, its preparation method, and its application. The radioactive preparation obtained by labeling it with a radionuclide exhibits high uptake in bacterial infections and a good abscess / non-target ratio, making it a novel radiopharmaceutical for bacterial infections with significant potential for widespread application. Detailed Implementation

[0019] This invention provides a proline-containing antimicrobial peptide UBI 29-41 derivative, and also discloses a method for preparing and using this derivative. The following examples will illustrate the invention in more detail, but do not in any way limit the scope of protection of the invention to the listed embodiments.

[0020] In a preferred embodiment, the present invention provides a structural formula as follows: 99m Tc-PUBI-M radioactive agents:

[0021]

[0022]

[0023] In the formula: M is 99m Tc forms a stable state 99m The coligand components of Tc complexes are N-tris(hydroxymethyl)methylglycine (Tricine) and ethylenediamine-N,N'-diacetic acid (EDDA), N-tris(hydroxymethyl)methylglycine (Tricine) and sodium triphenylphosphine tri-m-sulfonate (TPPTS), N-tris(hydroxymethyl)methylglycine (Tricine) and sodium diphenylphosphine-3-sulfonate (TPPMS), N-tris(hydroxymethyl)methylglycine (Tricine), N-tris(hydroxymethyl)methylglycine (Tricine) and 2-(pyridin-4-yl)acetic acid (PA), N-tris(hydroxymethyl)methylglycine (Tricine) and nicotinic acid (NIC), N-tris(hydroxymethyl)methylglycine (Tricine) and isonicotinic acid (ISONIC), N-tris(hydroxymethyl)methylglycine (Tricine) and 3,5-pyridinedicarboxylic acid (PDA), and N-tris(hydroxymethyl)methylglycine (Tricine) and 3-pyridinesulfonic acid (PSA).

[0024] The preparation steps are as follows:

[0025] a. Synthesis of ligand PUBI

[0026] Synthesis of ligand T-PUBI: A solid-phase peptide synthesis method was used. A calculated amount of Fmoc-Arg(Pbf)-OH resin was weighed and poured into a reaction column. DMF was added and the column was soaked for 30 minutes, then dried. An appropriate amount of deprotection solution (piperidine = 20% hexahydropyridine + 80% DMF) was added to the reaction column, and the column was agitated under nitrogen for 30 minutes. The column was dried, and an appropriate amount of DMF was added. Nitrogen gas was applied and the column was agitated for 2 minutes. This process was repeated 6 times. Three molar amounts of the protected amino acid and 2.85 molar amounts of HBTU (condensing agent) were weighed. The prepared protected amino acid and HBTU were added to the reaction column, followed by six molar amounts of NMM (organic base) to the resin. The column was agitated under nitrogen for 30 minutes. The solution in the reaction column was dried, washed with an appropriate amount of DMF, agitated under nitrogen for 2 minutes, and dried. This process was repeated 3 times. After identifying and linking amino acids, repeat the above steps sequentially, following the sequence from C-terminus to N-terminus: Fmoc-Arg(Pbf)-OH, Fmoc-Asn(Trt)-OH, Fmoc-Arg(Pbf)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Gln(Trt)-OH, Fmoc-Met-OH, Fmoc-Arg(Pbf)-OH, Fmoc-Arg(Pbf)-OH, Fmoc-Lys(Boc)-OH, Fmoc-Ala-OH, Fmoc-Arg(Pbf)-OH, Fmoc-Gly-OH, Fmoc-Thr(tBu)-OH, Fmoc-(D / L-Pro)-OH, HYNIC-COOH (without Fmoc protection, used for final N-terminal linking).

[0027] After the last amino acid was added and the protective agent was removed and washed, the column was dried under vacuum. A suitable amount of methanol was added to the reaction column, and the column was agitated with nitrogen for 2 minutes. The column was then dried under vacuum again, followed by the addition of a suitable amount of DCM, agitation with nitrogen for 2 minutes, and the process was repeated three times. Finally, a suitable amount of methanol was added to the reaction vessel, and the column was agitated with nitrogen for 2 minutes. This process was repeated twice. The resin was then placed in a suitable container and vacuum dried in a desiccator for 12 hours before cutting. The dried resin was then placed in a suitable round-bottom flask, and a suitable amount of the prepared cutting solution (1 g / 10 ml) was added. The flask was placed in a constant-temperature shaker at 25°C and shaken for 2 hours. Filtration: The resin particles were filtered out using a 50 mL sintered glass funnel. The filtrate was then poured into a glass container in a centrifuge tube, and 6-8 times the volume of anhydrous diethyl ether was added while stirring. The precipitated white solid was the desired crude polypeptide. The white solid was aliquoted into centrifuge tubes, sealed, and centrifuged at 4000 rpm for 3 minutes. The supernatant was discarded, and ether was added. The mixture was stirred thoroughly with a glass rod and centrifuged again. This washing process was repeated 5 times. The washed peptide was then placed in a vacuum desiccator and dried for 24 hours. The resulting white powder was the crude peptide. After weighing, it was purified by preparative HPLC to obtain HYNIC-(D / L-Pro)-TGRAKRRMQYNRR(T-PUBI).

[0028] The specific synthesis route is as follows:

[0029]

[0030] Synthesis of ligand K-PUBI: 100 mg of UBI 29-41 sample and 100 mg of HYNIC-P-NHS sample were weighed. UBI 29-41 sample was dissolved in pure water to a volume of 20 mL. The D / L-proline-modified HYNIC activated ester (HYNIC-P-NHS) sample was dissolved in 70% acetonitrile aqueous solution to a volume of 20 mL. The dissolved UBI 29-41 and HYNIC-P-NHS were poured into a 50 mL glass beaker and mixed thoroughly. The pH of the sample was adjusted to between 7.0 and 7.4 using 20 mmol / L NH4HCO3 aqueous solution. The sample was then placed in a 30℃ water bath and stirred. Samples were taken for analysis every 1 hour, and the reaction was terminated after approximately 5 hours. Purified water was added to the sample to achieve an acetonitrile content of approximately 15%. The sample was filtered and purified by HPLC using 0.1% TFA. Samples with a purity greater than 90% were collected to obtain ligand K-PUBI.

[0031] The specific synthesis route is as follows:

[0032]

[0033] b. 99m Preparation of Tc-PUBI-M complex

[0034] Dissolve PUBI and Tricine in physiological saline, add EDDA, ​​TPPTS, TPPMS, PA, NIC, ISONIC, PDA, or PSA, add SnCl2·2H2O, adjust the pH of the solution to approximately 5.0-7.0, and then add freshly rinsed Na+. 99m The TcO4 solution, reacted at 100℃ for 20-30 minutes, yields the aforementioned product. 99m Tc-PUBI-M complex.

[0035] Prepared by the above method 99m The Tc-PUBI-M complex has a radiochemical purity greater than 90%, is a hydrophilic substance, and exhibits good in vitro stability. 99m The Tc-PUBI-M complex exhibits specific uptake at bacterial infection sites, showing good uptake and abscess / non-target ratio at abscess sites in bacterial-infected mice. As a novel bacterial-targeting infection imaging agent, it is worthy of widespread application.

[0036] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed in accordance with the techniques or conditions described in the literature in the field, or in accordance with the product manual.

[0037] The invention is described in detail below through examples: a proline-containing antimicrobial peptide UBI 29-41 derivative, its preparation method, and its application, which can be used for SPECT / CT imaging specifically targeting bacterial infections. Its general structural formula is... 99m Tc-PUBI-M.

[0038]

[0039]

[0040] In the formula: M is 99m Tc forms a stable state 99mThe coligand components in Tc complexes are N-tris(hydroxymethyl)methylglycine (Tricine) and ethylenediamine-N,N'-diacetic acid (EDDA), N-tris(hydroxymethyl)methylglycine (Tricine) and sodium triphenylphosphine tri-m-sulfonate (TPPTS), N-tris(hydroxymethyl)methylglycine (Tricine) and sodium diphenylphosphine-3-sulfonate (TPPMS), N-tris(hydroxymethyl)methylglycine (Tricine), N-tris(hydroxymethyl)methyl... Tricine and 2-(pyridin-4-yl)acetic acid (PA), N-tris(hydroxymethyl)methylglycine and nicotinic acid (NIC), N-tris(hydroxymethyl)methylglycine and isonicotinic acid (ISONIC), N-tris(hydroxymethyl)methylglycine and 3,5-pyridinedicarboxylic acid (PDA), N-tris(hydroxymethyl)methylglycine and 3-pyridinesulfonic acid (PSA), etc.

[0041] 99m The preparation method of Tc-PUBI-M is as follows, but is not limited to the exemplified complex:

[0042] a. Synthesis of ligand PUBI

[0043] Synthesis of ligand T-DPUBI: A solid-phase synthesis method was employed, starting with arginine protected by a 2 mmol Pbf group immobilized on CTC resin. The ligands, arranged sequentially from C-terminus to N-terminus, were Fmoc-Arg(Pbf)-OH, Fmoc-Asn(Trt)-OH, Fmoc-Arg(Pbf)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Gln(Trt)-OH, Fmoc-Met-OH, Fmoc-Arg(Pbf)-OH, and Fmoc-Arg(Pbf)-OH. Fmoc-Lys(Boc)-OH, Fmoc-Ala-OH, Fmoc-Arg(Pbf)-OH, Fmoc-Gly-OH, Fmoc-Thr(tBu)-OH, Fmoc-(D / L-Pro)-OH, and HYNIC-COOH (without Fmoc protection, used for final N-terminal connection) were used. Finally, the protection and CTC resin were removed with a mixture of trifluoroacetic acid, triisopropylsilane, and water to obtain the crude product.

[0044] The crude product was separated and purified by preparative RP-HPLC, and the purified product was analyzed by analytical RP-HPLC and LC-MS. T-DPUBI (50 mg, purity 95.06%), HR-MS (ESI) for C 79 H 135 N 35 NaO20 S[M+2H] 4+ :found963.0160,calcd 963.0166.

[0045]

[0046] Synthesis of ligand K-PUBI: 100 mg of UBI 29-41 sample and 100 mg of HYNIC-P-NHS sample were weighed. UBI 29-41 sample was dissolved in pure water to a volume of 20 mL. The D / L-proline-modified HYNIC activated ester (HYNIC-P-NHS) sample was dissolved in 70% acetonitrile aqueous solution to a volume of 20 mL. The dissolved UBI 29-41 and HYNIC-P-NHS were poured into a 50 mL glass beaker and mixed thoroughly. The pH of the sample was adjusted to between 7.0 and 7.4 using 20 mmol / L NH4HCO3 aqueous solution. The sample was then placed in a 30℃ water bath and stirred. Samples were taken for analysis every 1 hour, and the reaction was terminated after approximately 5 hours. Purified water was added to the sample to achieve an acetonitrile content of approximately 15%. The sample was filtered and purified by HPLC using 0.1% TFA. Samples with a purity greater than 90% were collected to obtain ligand K-PUBI. K-DPUBI (16 mg, yield 12%, purity 97.45%), HR-MS (ESI) for C 86 H 140 N 35 NaO 23 S2[M+4H] 4+ Found 698.3419, calcd 698.3428. K-LPUBI (24 mg, yield 18%, purity 94.45%), HR-MS (ESI) for C 86 H 140 N 35 NaO 23 S2[M+4H] 4+ :found 698.3421,calcd 698.3428.

[0047]

[0048] b. 99m Preparation of Tc-T-DPUBI-EDDA complex

[0049] Take 20 μg of ligand T-DPUBI, add 20 mg of N-tris(hydroxymethyl)methylglycine (Tricine), dissolve in 0.3 mL of PBS (0.01 mol / L, pH = 7.4), 200 μL of ethylenediamine-N,N'-diacetic acid (EDDA, ​​50 mg / mL, 0.5 mol / L NaOH), and 100 μg of SnCl2·2H2O. Adjust the pH to 7-8 with 0.1 mol / L NaOH solution, transfer to a vacuum flask, and then add 0.3 mL of Na... 99m The TcO4 eluent was reacted in a boiling water bath for 30 minutes, then cooled to room temperature to obtain the target complex. 99m Tc-T-DPUBI-EDDA.

[0050]

[0051] c. 99m Preparation of Tc-T-DPUBI-TPPTS complex

[0052] Take 20 μg of ligand T-DPUBI, add 2 mg of N-tris(hydroxymethyl)methylglycine (Tricine) and 3 mg of sodium triphenylphosphine tris(m-sulfonate) (TPPTS), dissolve in 0.2 mL of physiological saline, add 0.3 mL of succinate buffer (0.5 mol / L, pH = 5.0), mix well, transfer to a vacuum bottle, and then add 0.5 mL of Na... 99m The TcO4 eluent was reacted in a boiling water bath for 30 minutes, then cooled to room temperature to obtain the target complex. 99m Tc-T-DPUBI-TPPTS.

[0053]

[0054] d. 99m Preparation of Tc-K-DPUBI-TPPTS complex

[0055] Take 20 μg of ligand K-DPUBI, add 2 mg of N-tris(hydroxymethyl)methylglycine (Tricine) and 3 mg of sodium triphenylphosphine tris(m-sulfonate) (TPPTS), dissolve in 0.2 mL of physiological saline, add 0.3 mL of succinate buffer (0.5 mol / L, pH = 5.0), mix well, transfer to a vacuum bottle, and then add 0.5 mL of Na... 99m The TcO4 eluent was reacted in a boiling water bath for 30 minutes, then cooled to room temperature to obtain the target complex. 99m Tc-K-DPUBI-TPPTS.

[0056]

[0057] e.99m Preparation of Tc-K-LPUBI-TPPTS complex

[0058] Take 20 μg of ligand K-LPUBI, add 2 mg of N-tris(hydroxymethyl)methylglycine (Tricine) and 3 mg of sodium triphenylphosphine tris(m-sulfonate) (TPPTS), dissolve in 0.2 mL of physiological saline, add 0.3 mL of succinate buffer (0.5 mol / L, pH = 5.0), mix well, transfer to a vacuum bottle, and then add 0.5 mL of Na 99m The TcO4 eluent was reacted in a boiling water bath for 30 minutes, then cooled to room temperature to obtain the target complex. 99m Tc-K-LPUBI-TPPTS.

[0059]

[0060] Experiments show that coordination compounds 99m The performance of Tc-PUBI-M is as follows:

[0061] 1. Identification of coordination compounds

[0062] a. Identification by high performance liquid chromatography (HPLC):

[0063] A C18 analytical column and high-performance liquid chromatography (HPLC) were used. Phase A was water (containing 0.1% trifluoroacetic acid), and phase B was acetonitrile (containing 0.1% trifluoroacetic acid). The gradient was 0-2 min (10% B), 2-5 min (10%-90% B), 5-15 min (90% B), and 15-25 min (90%-10% B), with a flow rate of 1 mL / min. Retention time (t) was determined. R )for: 99m Tc-T-DPUBI-EDDA: 9.919 min; 99m Tc-T-DPUBI-TPPPTS: 9.702min; 99m Tc-K-DPUBI-TPPPTS: 9.774min; 99m Tc-K-LPUBI-TPPPTS: 9.755min;

[0064] b. Identification by thin-layer chromatography (TLC):

[0065] The development system was as follows: silica gel-impregnated glass microfiber chromatographic paper (iTLC-SG) was used as the support, and citric acid-glucose solution (ACD) was used as the developing solvent. Under this system, the R0 of each radioactive component was... f The values ​​are shown in the table below.

[0066] Table 1 Chromatographic results of each component of the complex (R f value)

[0067]

[0068] The radiochemical purity of the markers determined by the above chromatographic identification is greater than 90%.

[0069] 2. Determination of the lipid-water partition coefficient of the complex

[0070] Take 1.0 mL of n-octanol and 0.9 mL of phosphate buffer (pH 7.4, 0.025 mol / L) into a 2 mL centrifuge tube. Add 0.1 mL of the complex solution to the centrifuge tube, stopper the tube, vortex to mix thoroughly, and centrifuge for 5 min (3000 r / min). Take 0.1 mL from both the organic and aqueous phases, measure the radioactivity counts of both phases, and calculate the Log D value (D = radioactivity of organic phase / radioactivity of aqueous phase). The lipid-water partition coefficient of the complex is shown in the table below after four parallel measurements.

[0071] Table 2. Results of lipid-water partition coefficients of the complexes.

[0072]

[0073] The results of the lipid-water partition coefficient indicate that all complexes are water-soluble substances.

[0074] 3. In vitro stability determination of the complex

[0075] The radiochemical purity of the prepared complex was determined after being placed in mouse serum at room temperature and at 37°C for 6 hours. The results showed that the radiochemical purity of the complex was greater than 90% after being placed in mouse serum at room temperature and at 37°C for 6 hours, indicating that it has good in vitro stability.

[0076] 4. Biodistribution of the complex in mice with bacterial infection

[0077] Establishment of a mouse model of bacterial infection: 0.1 mL of Staphylococcus aureus (1×10⁻⁶) was administered. 9 0.1 mL (approximately 1.85 × 10⁻⁶ mL) was injected into the left hind leg muscle of 18–22 g Kunming mice. 24 hours later, mice showing obvious infection were used for biodistribution experiments. The biodistribution experiment was performed on these model mice by injecting 0.1 mL (approximately 1.85 × 10⁻⁶ mL) via the tail vein. 5 The mice were anesthetized and euthanized 60 minutes after injection of the Bq complex. Different organs, abscessed muscles, and contralateral thigh muscles were collected, weighed, and their radioactivity counts were measured on a γ-counter. Five model mice were used for each time phase. The percentage injection dose per gram (%ID / g) for each tissue was calculated. The results are shown in Tables 3 and 4.

[0078] Table 3 99mBiodistribution of Tc-T-DPUBI-M in bacterially infected mice (60 min pi, n=5, %ID / g)

[0079]

[0080]

[0081] Table 4 99m Biodistribution of Tc-K-PUBI-TPPTS in bacterially infected mice (60 min pi, n = 5, %ID / g)

[0082]

[0083] The results above indicate that the complex has high uptake at the site of bacterial infection and low uptake in non-target areas such as the kidneys, blood, and muscle, with good abscess-to-muscle and abscess-to-blood ratios.

[0084] 5. SPECT imaging of the complex in a mouse model of bacterial infection.

[0085] Establishment of a mouse model of bacterial infection for imaging: 0.1 mL of Staphylococcus aureus (1 × 10⁻⁶) was injected into the left foreleg muscle of Kunming mice. 9 / mL), and SPECT / CT imaging was performed 24 hours later (n=2). SPECT imaging results showed that it had significant radioactive uptake at the site of bacterial infection.

[0086] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention, except for the proline-containing antimicrobial peptide UBI involved in this invention, are... Besides derivatives 29-41, radioactive agents obtained by changing different linkers, such as amino acids, peptide chains, polyethylene glycol (PEG) chains, aliphatic chains, etc., or by using triphenylphosphine and sodium triphenylphosphine tris(m-sulfonate) (TPPTS), triphenylphosphine and disodium 3,3'-(phenylphosphinediyl)bis(phenyl-1-sulfonic acid) (TPPDS), triphenylphosphine and sodium diphenylphosphine-3-sulfonate (TPPMS), triphenylphosphine and nicotinic acid (NIC), triphenylphosphine and isonicotinic acid (ISONIC), triphenylphosphine and 3,5-pyridinedicarboxylic acid (PDA), triphenylphosphine and 2,6-pyridinedicarboxylic acid (2,6-PDA), triphenylphosphine and 3-pyridinesulfonic acid (PSA), triphenylphosphine and 3-pyridinesulfonic acid (4-PSA), triphenylphosphine and glucohepanoate, triphenylphosphamine, triphenylphosphine and mannitol, triphenylphosphine and diphenylphosphine benzoic acid, etc., for radionuclide labeling, are all within the scope of protection of this invention.

Claims

1. A proline-containing antimicrobial peptide UBI 29-41 derivative, characterized in that, The structural formula of the D-proline-modified N-terminal threonine-containing antimicrobial peptide UBI 29-41 derivative is (I):

2. A proline-containing antimicrobial peptide UBI 29-41 derivative, characterized in that, The structural formula of the L-proline-modified N-terminal threonine-containing antimicrobial peptide UBI 29-41 derivative is (II):

3. A proline-containing antimicrobial peptide UBI 29-41 derivative, characterized in that, The structural formula of the D-proline-modified lysine-5 antimicrobial peptide UBI 29-41 derivative is (Ⅲ):

4. A proline-containing antimicrobial peptide UBI 29-41 derivative, characterized in that, The structural formula of the L-proline-modified 5-lysine antimicrobial peptide UBI 29-41 derivative is (Ⅳ):

5. A radioactive preparation, characterized in that, The radioactive preparation comprises the proline-modified antimicrobial peptide UBI 29-41 derivative of claims 1-4 labeled with a radionuclide.

6. The radioactive agent according to claim 5, characterized in that, The radioactive nuclide is 99m Tc, 99 Tc, 94m Tc, 94 Tc, 52 Mn, 186 Re or 188 Re.

7. The radioactive agent according to claim 6, characterized in that, The structural formula of the radioactive agent is (V): In the formula: M represents N-tris(hydroxymethyl)methylglycine and ethylenediamine-N,N'-diacetic acid, N-tris(hydroxymethyl)methylglycine and sodium triphenylphosphine tri-m-sulfonate, N-tris(hydroxymethyl)methylglycine and sodium diphenylphosphine-3-sulfonate, N-tris(hydroxymethyl)methylglycine and 2-(pyridin-4-yl)acetic acid, N-tris(hydroxymethyl)methylglycine and nicotinic acid, N-tris(hydroxymethyl)methylglycine and isonicotinic acid, N-tris(hydroxymethyl)methylglycine and 3,5-pyridinedicarboxylic acid, and N-tris(hydroxymethyl)methylglycine and 3-pyridinesulfonic acid.

8. The use of the radioactive agent according to any one of claims 5-7 in the preparation of imaging agents for bacterial infections.

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