A ruthenium polypyridyl complex with a benzene sulfonyl indole structure modification for inhibiting bacterial toxin and a preparation method and application thereof

Abstract

The present application belongs to the technical field of antibacterial medicine, and particularly relates to a benzene sulfonyl indole structure modified ruthenium polypyridyl complex with the function of inhibiting bacterial toxin as well as a preparation method and application thereof. The benzene sulfonyl indole structure modified ruthenium polypyridyl complex has the following structure: The benzene sulfonyl indole structure modified ruthenium polypyridyl complex not only has excellent antibacterial ability, but also does not induce bacterial drug resistance. The benzene sulfonyl indole structure modified ruthenium polypyridyl complex can be used in combination with polymyxin B to achieve better antibacterial effect. In addition, it is found that the benzene sulfonyl indole structure modified ruthenium polypyridyl complex has certain antibiofilm effect, and the mechanism thereof is further studied. The complex can also effectively inhibit the hemolysis phenomenon caused by bacteria and has concentration dependence.

Description

Technical Field

[0001] This invention belongs to the field of antibacterial pharmaceutical technology, specifically relating to a benzenesulfonylindole structure-modified ruthenium polypyridine complex that inhibits bacterial toxins, its preparation method, and its application. Background Technology

[0002] With the escalating problem of antibiotic overuse, drug-resistant bacterial infections have become a major global public health challenge. According to reports from the World Health Organization (WHO) and public health departments in various countries, the incidence and mortality rates of drug-resistant bacterial infections are increasing year by year. The global antimicrobial drug market is enormous, and the demand for new antimicrobial drugs will continue to grow as the problem of drug resistance intensifies.

[0003] Antibiotic combination therapy refers to the simultaneous use of two or more antibiotics to treat an infection. When the pathogen of the infection is unclear, combination antibiotics can cover a wider range of bacteria, ensuring effective treatment. Some antibiotic combinations can enhance antibacterial effects; for example, the combination of β-lactams and aminoglycosides is often used to treat severe infections. Combination antibiotic therapy can reduce the risk of bacteria developing resistance, especially when treating infections prone to resistance, such as tuberculosis.

[0004] Bacterial biofilms are structured communities of bacteria that form on their surfaces, encapsulated in extracellular polymers secreted by the bacteria themselves. These extracellular polymers, primarily composed of polysaccharides, proteins, DNA, and lipids, provide protection and stability for the bacteria. Biofilms are associated with a variety of chronic infections, such as lung infections in patients with cystic fibrosis, chronic wound infections, and urinary tract infections. These infections are difficult to cure and prone to recurrence. Bacteria in biofilms exhibit significantly higher antibiotic resistance than planktonic bacteria, making treatment challenging.

[0005] Hemolysis is the process of red blood cell rupture and release of hemoglobin. Bacterial infections can trigger hemolysis through mechanisms such as toxins, enzymes, immune responses, or direct invasion of red blood cells.

[0006] Therefore, how to prepare substances that can inhibit bacterial toxins, inhibit hemolysis caused by bacteria, and remove bacterial biofilms is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a ruthenium polypyridine complex with a benzenesulfonylindole structure, its preparation method and application.

[0008] The technical solution of the present invention is as follows:

[0009] A first aspect of the present invention provides a benzenesulfonylindole structure-modified ruthenium polypyridine complex having the ability to inhibit bacterial toxins, having a structure as shown in Formula I:

[0010] Formula I;

[0011] Wherein, in equation I It has one of the following structures:

[0012] .

[0013] The ruthenium polypyridine complex with a benzenesulfonylindole structure involved in this invention possesses a unique antibacterial mechanism. The ruthenium ions in this complex carry a positive charge and can interact with the negatively charged bacterial cell membrane through electrostatic interactions. This interaction disrupts the phospholipid bilayer structure of the cell membrane, leading to the leakage of intracellular substances, inhibiting the production of bacterial toxins, and ultimately inhibiting bacterial growth. Furthermore, the multi-coordination configuration of the ruthenium complex allows for various ligand modifications, which not only enhances its biological activity but also reduces its toxicity, thereby increasing its application value as an antibacterial agent.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned benzenesulfonylindole structure-modified ruthenium polypyridine complex for inhibiting bacterial toxins, comprising the following steps:

[0015] The main ligand as shown in Formula a and the auxiliary ligand as shown in Formula b are dissolved in a solvent and a coordination substitution reaction is carried out under a protective atmosphere to introduce the main ligand into the auxiliary ligand, thereby obtaining a ruthenium polypyridine complex with a benzenesulfonylindole structure as shown in Formula I.

[0016] The synthetic route is shown below:

[0017]

[0018] Among them, in equation b and equation I It has one of the following structures:

[0019]

[0020] This invention employs ruthenium complexes as auxiliary ligands, leveraging their unique physicochemical properties to achieve antibacterial function. Ruthenium, as a transition metal, possesses complexes with excellent biocompatibility, superior electrochemical and photophysical properties, and the ability to bind with small molecule compounds and nanomaterials. Thanks to the rigid octahedral geometry of ruthenium complexes, they are easily modified, exhibiting high plasticity. Furthermore, the introduction of a benzenesulfonylindole structure may significantly enhance antibacterial activity. This structure may improve the compound's selectivity for bacteria through interactions with specific bacterial targets (such as enzymes or proteins), thereby enhancing the antibacterial effect. The hydrophobicity of benzenesulfonylindole may facilitate better penetration of the bacterial cell membrane, increasing its accumulation within the cell and thus more effectively disrupting the internal structure or metabolic processes of bacteria. The benzenesulfonylindole structure may interfere with bacterial metabolic pathways or signal transduction, inhibiting the synthesis and release of bacterial toxins and reducing bacterial pathogenicity. The synergistic effect between benzenesulfonylindole and ruthenium complexes further enhances antibacterial activity while reducing the development of bacterial resistance. This invention modifies polypyridine ruthenium complexes with benzenesulfonylindole structure, significantly enhancing their ability to penetrate bacterial cell membranes and their retention effect, thereby disrupting bacterial membrane structure, inhibiting the production of bacterial toxins, and achieving antibacterial effects.

[0021] Specifically, the auxiliary ligand has the chemical formula Ru(bpy)₂Cl₂·2H₂O, Ru(dtb)₂Cl₂·2H₂O, Ru(dmb)₂Cl₂·2H₂O, or Ru(dmp)₂Cl₂·2H₂O; Ru(bpy)₂Cl₂·2H₂O has the structure shown in formula c-1; Ru(dtb)₂Cl₂·2H₂O has the structure shown in formula c-2; Ru(4,4′-Ru(dmb)₂Cl₂·2H₂O has the structure shown in formula c-3; and Ru(dmp)₂Cl₂·2H₂O has the structure shown in formula c-4.

[0022]

[0023] Preferably, the molar ratio of the main ligand to the auxiliary ligand is 1:0.8~1.0.

[0024] Preferably, the coordination substitution reaction is carried out at a temperature of 140°C to 160°C for 7 to 9 hours.

[0025] Preferably, the method for preparing the host ligand includes the following steps:

[0026] When the compound shown in formula d and the compound shown in formula e are mixed, a ketaldehyde condensation reaction occurs under acid catalysis to form a main ligand containing benzenesulfonylindole.

[0027] The synthetic route is shown below:

[0028] .

[0029] Preferably, ammonium acetate is also added and mixed together; the acid is acetic acid.

[0030] During the reaction, ammonium acetate undergoes a certain degree of dissociation to generate ammonium ions, which then undergo a nucleophilic addition reaction with benzenesulfonylindole, followed by dehydration to form an imine product. Simultaneously, the nitrogen atom of the imine attacks the carbonyl carbon of 1,10-phenanthroline-5,6-dione, forming a new negatively charged oxygen intermediate. This negatively charged oxygen intermediate can react with another carbonyl group of 1,10-phenanthroline-5,6-dione through intramolecular electron and proton transfer processes, forming a new carbon-oxygen bond. Simultaneously, a double bond forms between the nitrogen atom and the other carbonyl carbon, resulting in an intramolecular cyclization reaction that generates a product containing a heterocyclic structure, yielding the host ligand containing benzenesulfonylindole.

[0031] Preferably, the molar ratio of the compound shown in formula d to the compound shown in formula e is 0.9~1.1:1.0~1.2. Preferably, the ketaldehyde condensation reaction is carried out at a temperature of 110℃~130℃ for 3h~5h.

[0032] A third aspect of the present invention provides the use of the above-described benzenesulfonylindole structured ruthenium polypyridine complex in the preparation of anti-Staphylococcus aureus products and / or products for eradicating biofilms formed by Staphylococcus aureus.

[0033] This invention explores the effects on biofilms. Bacterial biofilms are structured communities formed by bacteria on their surfaces, encapsulated in extracellular polymeric substances (EPS) secreted by the bacteria themselves. Biofilms are associated with various chronic infections, such as lung infections in patients with cystic fibrosis, chronic wound infections, and urinary tract infections. These infections are difficult to cure and prone to recurrence. Bacteria in biofilms exhibit much higher antibiotic resistance than planktonic bacteria, leading to treatment difficulties. Crystal violet staining is used, where crystal violet stains the biofilm. The intensity of the crystal violet color reflects the drug's effect on the biofilm. This invention demonstrates excellent anti-biofilm effects. The anti-biofilm activity further increases with increasing drug concentration. Vancomycin is a glycopeptide antibiotic primarily used to treat severe infections caused by Gram-positive bacteria. Vancomycin exerts its antibacterial effect by inhibiting bacterial cell wall synthesis. It specifically binds to the D-alanyl-D-alanine residue at the terminal end of peptidoglycan, a precursor to the bacterial cell wall, preventing the elongation and cross-linking of the peptidoglycan chain, thereby leading to incomplete bacterial cell wall structure and ultimately bacterial death. To further demonstrate the advantages of this invention, vancomycin was used as a comparison. It can be seen that this invention has excellent performance, and its anti-biofilm effect is basically the same as that of vancomycin as the concentration increases.

[0034] A fourth aspect of the present invention provides the use of the above-described benzenesulfonylindole structured ruthenium polypyridine complex in combination with an antibiotic in the preparation of an anti-Escherichia coli product.

[0035] This invention demonstrates synergistic effects with other antibiotics. When used in combination with polymyxin B, it effectively combats Escherichia coli infections, reducing the dosage of single antibiotics and minimizing side effects. When the infecting pathogen is unclear, combined antibiotic therapy can cover a wider range of bacteria, ensuring effective treatment and is suitable for mixed infections caused by multiple bacteria. Combined antibiotic therapy can reduce the probability of bacterial resistance, especially in treating infections prone to resistance, such as tuberculosis. Different antibiotics act on bacteria through different mechanisms, reducing the selective pressure from drug-resistant strains.

[0036] Preferably, the antibiotic is polymyxin B.

[0037] Preferably, the product includes a drug or an antibacterial agent.

[0038] This invention has at least one of the following beneficial effects:

[0039] This invention employs ruthenium complexes as auxiliary ligands, leveraging their unique physicochemical properties to achieve antibacterial function. Ruthenium, as a transition metal, possesses complexes with excellent biocompatibility, superior electrochemical and photophysical properties, and the ability to bind with small molecule compounds and nanomaterials. Thanks to the rigid octahedral geometry of ruthenium complexes, they are easily modified, exhibiting high plasticity. The polypyridine structure, a typical nitrogen-containing heterocyclic compound, provides more target sites, enabling disruption of bacterial cell membranes and thus inhibiting bacterial toxin production. Furthermore, the introduction of a benzenesulfonylindole structure may significantly enhance antibacterial activity. This structure may improve the compound's selectivity for bacteria through interactions with specific bacterial targets (such as enzymes or proteins), thereby enhancing the antibacterial effect. Through structural optimization, benzenesulfonylindole modification may improve the compound's biocompatibility and reduce its toxicity to host cells, thus improving its safety as an antibacterial agent. The benzenesulfonylindole structure may reduce existing antibiotic resistance problems by acting on unconventional bacterial targets, providing a new solution for combating drug-resistant bacteria. This invention develops a novel benzenesulfonylindole-modified ruthenium polypyridine complex that inhibits bacterial toxins, and provides its preparation method and applications. Antibacterial and drug resistance experiments show that this novel synthetic benzenesulfonylindole-modified ruthenium polypyridine complex exhibits good antibacterial activity and resistance to drug resistance, and shows promise as a novel and effective antibiotic against Staphylococcus aureus. Attached Figure Description

[0040] Figure 1 This is the hydrogen NMR spectrum of Ru-2.

[0041] Figure 2 This is the mass spectrum of Ru-2.

[0042] Figure 3 The antibacterial effects of Ru-2 complexes treated with different concentrations and for different durations on Staphylococcus aureus were investigated.

[0043] Figure 4 The Ru-2 complex, in combination with polymyxin B, is used to combat Escherichia coli infection.

[0044] Figure 5 This is a comparison of the effects of Ru-2 complex and vancomycin on biofilm formation by Staphylococcus aureus.

[0045] Figure 6 It is a leakage of Staphylococcus aureus DNA under the action of Ru-2 complex.

[0046] Figure 7 It is a protein leak from Staphylococcus aureus under the action of Ru-2 complex.

[0047] Figure 8 The hemolytic rate of the Ru-2 complex at different concentrations of the present invention against Staphylococcus aureus is shown. Detailed Implementation

[0048] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0049] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0050] Example 1

[0051] This embodiment provides a method for preparing a benzenesulfonylindole structure-modified ruthenium polypyridine complex that inhibits bacterial toxins.

[0052] (1) Preparation of the host ligand:

[0053] 208.0 mg of 1,10-phenanthroline-5,6-dione (formula d), 210.6 mg of benzenesulfonylindole (formula e), and 2300.4 mg of ammonium acetate were weighed and placed in a 250 mL three-necked flask. 65 mL of acetic acid was added, and the mixture was refluxed and stirred at 120 °C for 4 h. After the reaction solution cooled, it was diluted with water, and the pH was adjusted to neutral with ammonia to precipitate a yellow precipitate. The precipitate was filtered under reduced pressure, and then purified by silica gel column chromatography using ethanol as the eluent to obtain a pure product. The purified product was then dried under vacuum to obtain the main ligand as shown in formula a, with a yield of 62%. The preparation reaction route is shown below:

[0054]

[0055] (2) Preparation of ruthenium polypyridine complexes with benzenesulfonylindole structure:

[0056] 108.7 mg of the main ligand as shown in formula a and 100.3 mg of Ru(dtb)₂Cl₂·2H₂O (formula c-2) were added to a 50 mL three-necked flask and dissolved in ethylene glycol. Under argon protection, the mixture was stirred and refluxed at 150 °C for 8 h. After the reaction was completed, the mixture was cooled to room temperature, and a large amount of reddish-brown solid precipitated after the addition of saturated potassium hexafluorophosphate solution. The precipitate was filtered and collected, and dried under vacuum to obtain the crude product. The crude product was purified by separation using a neutral alumina column with a concentration gradient elution of a mixed solution of xylene and acetonitrile. The volume ratio of xylene to acetonitrile was 10:1 to obtain a benzenesulfonylindole-modified polypyridine ruthenium complex, denoted as Ru-2, with a yield of 68%. The preparation reaction route is shown below:

[0057]

[0058] The structural formula of Ru(dtb)2Cl2·2H2O is shown in c-2.

[0059] In addition, Ru(dtb)2Cl2·2H2O in step (2) was replaced with Ru(bpy)2Cl2·2H2O, Ru(dmb)2Cl2·2H2O or Ru(dmp)2Cl2·2H2O respectively. The other steps were the same as the preparation process of Ru-2. Three other benzenesulfonylindole modified polypyridine ruthenium complexes were prepared and were denoted as Ru-1, Ru-3 and Ru-4 respectively.

[0060] The structural formulas of Ru(bpy)2Cl2·2H2O, Ru(dmb)2Cl2·2H2O, or Ru(dmp)2Cl2·2H2O are shown in c-1, c-3, and c-4, respectively.

[0061]

[0062] The prepared product Ru-2 was characterized by 1H NMR and mass spectrometry, and the results are as follows: Figure 1 , 2 As shown: 1 HNMR (400MHz, DMSO) δ69.00(s, 2H), 8.87 (d, J = 15.3 Hz, 5H), 8.11 - 8.01(m, 3H), 7.83(s, 3H), 7.70 (t, J= 6.3 Hz, 3H), 7.66 - 7.59(m, 4H), 7.46 (d, J = 5.9 Hz, 4H), 7.35 (d, J = 6.0 Hz, 2H), 7.11 (d, J = 7.2 Hz, 1H), 7.05 (d, J = 6.0, 2.9 Hz, 1H),6.99 - 6.93 (m, 1H), 1.42 (d, J = 1.5Hz, 18H), 1.33(d, J = 1.5 Hz, 18H).

[0063] The MIC values ​​of Ru-1, Ru-2, Ru-3, and Ru-4 were determined using the following method:

[0064] Staphylococcus aureus strains were cultured in TSB medium to the logarithmic growth phase; the bacterial suspensions were then diluted 1000-fold with fresh medium. Different concentrations of Ru-2 were added sequentially to each well of a 96-well plate, followed by 200 µL of bacterial suspension to each well, resulting in final Ru-2 concentrations of 100 µg / mL, 50 µg / mL, 25 µg / mL, 12.5 µg / mL, 6.25 µg / mL, 3.125 µg / mL, 1.56 µg / mL, 0.78 µg / mL, and 0.39 µg / mL from left to right. The last well contained 50 µL of sterile water as a blank control. Each drug was tested in triplicate. After incubation at 37°C for 20 h, bacterial growth was monitored by observing the turbidity of the culture. The lowest drug concentration corresponding to the clear administration well was the MIC (minimum inhibitory concentration).

[0065] The MIC values ​​of Ru-1, Ru-3, and Ru-4 were determined using the same method described above.

[0066] The MIC values ​​of Ru-1, Ru-2, Ru-3 and Ru-4 were determined to be 3.5 μg / mL, 1.56 μg / mL, 5.0 μg / mL and 12.5 μg / mL, respectively.

[0067] Example 2

[0068] This embodiment provides experiments on DNA and protein leakage of the benzenesulfonylindole-modified polypyridine ruthenium complex Ru-2 prepared in Example 1.

[0069] Staphylococcus aureus was revived and cultured in TSB liquid medium at 37°C for 24 hours. The bacterial population density was determined by measuring absorbance at 600 nm using a microplate reader. Specific treatments were applied to induce cell membrane damage. The cell culture medium was centrifuged, and the supernatant was collected. The DNA / protein content in the supernatant was determined using a spectrophotometer. The amount of DNA / protein leakage between different treatment groups was compared to assess the degree of cell membrane damage.

[0070] The specific processing methods for different treatment groups are as follows:

[0071] Group Ru-2: Take OD 600 To prepare Ru-2 solutions with final concentrations of 1.56 µg / mL and 3.125 µg / mL for Staphylococcus aureus at 0.3 g / mL, incubate for 2–4 hours, and then centrifuge. Measure the absorbance of the supernatant at 260 nm and 280 nm.

[0072] Polymyxin B group: OD 600 Polymyxin B was prepared at final concentrations of 1.56 µg / mL and 3.125 µg / mL for Staphylococcus aureus at 0.3 μg / mL. After incubation for 2-4 hours and centrifugation, the absorbance values ​​of the supernatant at 260 nm and 280 nm were measured.

[0073] Control group: OD 600 Staphylococcus aureus at 0.3 g / L was incubated for 2-4 hours, and after centrifugation, the absorbance of the supernatant at 260 nm and 280 nm was measured.

[0074] The degree of cell membrane damage, such as Figure 6 and Figure 7 As shown, by Figure 6 and Figure 7 It can be seen that the OD of the Ru-2 group 260 OD 280 Both were greater than polymyxin B and the control group, indicating that Ru-2 has a stronger disruptive effect on the cell membrane, causing DNA and proteins to leak out of the cell. This also shows that Ru-2 exerts its antibacterial effect by disrupting the cell membrane.

[0075] This invention investigates the antibacterial mechanism of the benzenesulfonylindole-modified ruthenium polypyridine complex. To explore the antibacterial mechanism, DNA leakage and protein leakage were detected. DNA leakage can detect cell membrane integrity; by detecting the DNA content in the extracellular medium, the degree of cell membrane damage can be indirectly assessed. Protein leakage is another verification experiment for cell membrane disruption. After the cell membrane is disrupted, substances leak out; detecting the protein content in the extracellular medium can also reflect membrane integrity. Using polymyxin B as a control, this invention exhibits a stronger disruptive effect on the cell membrane at the same concentration, with DNA and proteins leaking out of the cell, demonstrating that the invention exerts its antibacterial effect by disrupting the cell membrane. The hydrophobicity of benzenesulfonylindole may facilitate better penetration of the bacterial cell membrane, increasing its accumulation within the cell, thereby more effectively disrupting the internal structure or metabolic processes of bacteria. The benzenesulfonylindole structure may interfere with bacterial metabolic pathways or signal transduction, inhibiting the synthesis and release of bacterial toxins and reducing bacterial pathogenicity. Benzylindole and ruthenium complexes exhibit a synergistic effect, further enhancing antibacterial activity while reducing the development of bacterial resistance. This invention modifies polypyridine ruthenium complexes with benzylindole structures, significantly enhancing their ability to penetrate bacterial cell membranes and their retention effect, thereby disrupting bacterial membrane structures, inhibiting bacterial toxin production, and achieving antibacterial effects.

[0076] Example 3

[0077] This embodiment provides an experiment on the effect of benzenesulfonylindole-modified polypyridine ruthenium complex Ru-2 prepared in Example 1 on biofilm formation by Staphylococcus aureus.

[0078] In the crystal violet staining method, Staphylococcus aureus was diluted in TSB at a concentration of 10. 7 CFU mL −1 Subsequently, 1 mL of bacterial solution was added to each well of a 24-well plate and incubated at 37°C for 24 hours. After incubation, the plates were washed three times with PBS, and then different treatment groups were performed. After treatment, the plates were washed again with PBS and dried for 30 minutes. The next step was to stain with 5% (v / v) crystal violet solution for 1 hour, followed by the addition of 33% (v / v) acetic acid after removing the staining solution. Finally, the absorbance was measured at 595 nm.

[0079] The specific processing methods for different treatment groups are as follows:

[0080] Ru-2 group: Ru-2 concentrations of 1.56 µg / mL, 3.125 µg / mL, 6.25 µg / mL, 12.5 µg / mL, 25 µg / mL, and 50 µg / mL were prepared and added to 24-well plates and incubated for 24 hours.

[0081] Vancomycin group: Vancomycin was prepared at final concentrations of 1.56 µg / mL, 3.125 µg / mL, 6.25 µg / mL, 12.5 µg / mL, 25 µg / mL, and 50 µg / mL and added to 24-well plates for incubation for 24 hours.

[0082] Control group: Incubated with PBS for 24 hours.

[0083] The results are as follows Figure 5 As shown, Figure 5 This is a comparison of the effects of Ru-2 complexes and vancomycin on biofilm formation by Staphylococcus aureus. Figure 5 It can be seen that the OD of the Ru-2 group 595 The levels were lower than the control group and comparable to the vancomycin group, indicating that the Ru-2 complex has the ability to eradicate Staphylococcus aureus biofilms, with effects comparable to the vancomycin group. This also demonstrates that the Ru-2 complex can penetrate biofilms and exert its antibacterial activity more effectively.

[0084] Example 4

[0085] This embodiment provides a hemolysis experiment of Ru-2, a polypyridine ruthenium complex modified with benzenesulfonylindole prepared in Example 1.

[0086] Red blood cells were obtained from the eye of a healthy 6-week-old male BALB / c mouse. The red blood cells were then centrifuged at 8000 rpm for 5 minutes, the supernatant was removed, and the red blood cells were washed three times with PBS before dilution for further use. The diluted red blood cells, bacteria, and other components were prepared at concentrations ranging from 0 to 0.9 μg / mL. -1 Ru-2 was mixed. TX-100 and PBS were used as positive and negative controls, respectively. The mixture was incubated at 37°C for 30 minutes, and then centrifuged again at 8000 rpm for 5 minutes. The absorbance of the supernatant was measured at 540 nm to assess the hemolysis rate, calculated using the following formula: Hemolysis rate (%) = (Ah – An) / (Ap – An) × 100%. In this formula, Ah, Ap, and An represent the absorbance values ​​of the supernatant in the Ru-2 group, positive control group, and negative control group, respectively.

[0087] The results are as follows Figure 8 As shown, Figure 8 The hemolysis rate of Ru-2 complexes at different concentrations. Figure 8 As shown, via OD 543nm The concentration was determined quantitatively by absorbance at 0.3 μg / mL. -1 0.6 μg mL -1 and 0.9 μg mL -1The hemolytic rate of Ru-2 was measured. Ru-2 complexes have an inhibitory effect on the hemolysis of Staphylococcus aureus and can inhibit the production of Staphylococcus aureus toxins, and this effect is concentration-dependent.

[0088] Example 5

[0089] This embodiment provides an antibacterial experiment of Ru-2, a benzenesulfonylindole-modified polypyridine ruthenium complex prepared in Example 1.

[0090] Staphylococcus aureus was revived and cultured in TSB liquid medium at 37°C for 24 hours. The bacterial population density was determined by measuring absorbance at 600 nm using a microplate reader. After treatment with different concentrations and times, each group was incubated at 37°C for 50 minutes. Subsequently, the diluted bacterial suspension was evenly spread onto TSB solid medium plates and incubated at 37°C for 15 hours. After incubation, the number of bacterial colonies formed on the plates was counted and recorded.

[0091] The results are as follows Figure 3 As shown, Figure 3 To investigate the antibacterial effects of Ru-2 complexes treated with different concentrations and for different durations against Staphylococcus aureus, [the following was conducted]. Figure 3 It can be seen that at a concentration of 4 µg / mL, bacterial growth was inhibited, and the antibacterial effect increased with increasing concentration. Furthermore, at a concentration of 8 µg / mL, after 2 hours of treatment, the bacteria were essentially dead. This indicates that the Ru-2 complex has a good antibacterial effect.

[0092] Example 6

[0093] This embodiment provides an experiment on the use of the Ru-2 complex prepared in Example 1 in combination with polymyxin B to combat Escherichia coli infection.

[0094] 25 µL of Ru-2, 25 µL of polymyxin B, and 200 µL of bacterial culture were mixed, and concentration gradients of the two drugs were set up in a 96-well plate, one increasing along the X-axis and the other along the Y-axis. Bacterial growth was observed under different concentration combinations. The combined inhibitory effect was calculated. The Fractional Inhibitory Concentration Index (FICI) was calculated to determine whether the antibiotic combination had a synergistic effect (FICI < 0.5), an additive effect (0.5 ≤ FICI ≤ 1), or an antagonistic effect (FICI > 1). Results are as follows: Figure 4 As shown, Figure 4 This is a Ru-2 complex used in combination with polymyxin B to combat Escherichia coli infection. Figure 4 It can be seen that the Ru-2 complex has a synergistic effect when used in combination with polymyxin B.

[0095] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0096] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A benzenesulfonylindole-modified ruthenium polypyridine complex with antibacterial toxin-inhibiting properties, characterized in that, It has the structure shown in Equation I: Formula I; Wherein, in equation I It has one of the following structures: 。 2. A method for preparing the benzenesulfonylindole structure-modified ruthenium polypyridine complex according to claim 1, characterized in that, Includes the following steps: The main ligand as shown in Formula a and the auxiliary ligand as shown in Formula b are dissolved in a solvent and a coordination substitution reaction is carried out under a protective atmosphere to introduce the main ligand into the auxiliary ligand, thereby obtaining a ruthenium polypyridine complex with a benzenesulfonylindole structure as shown in Formula I. The synthetic route is shown below: ； Among them, in equation b and equation I It has one of the following structures: 。 3. The preparation method according to claim 2, characterized in that, The molar ratio of the main ligand to the auxiliary ligand is 1:0.8~1.

0.

4. The preparation method according to claim 2, characterized in that, The coordination substitution reaction was carried out at a temperature of 140℃~160℃ for 7h~9h.

5. The preparation method according to claim 2, characterized in that, The preparation method of the host ligand includes the following steps: When the compound shown in formula d and the compound shown in formula e are mixed, a ketaldehyde condensation reaction occurs under acid catalysis to form a main ligand containing benzenesulfonylindole. The synthetic route is shown below: 。 6. The preparation method according to claim 5, characterized in that, The molar ratio of the compound shown in formula d to the compound shown in formula e is 0.9~1.1:1.0~1.

2.

7. The preparation method according to claim 5, characterized in that, The ketaldehyde condensation reaction was carried out at a temperature of 110℃ to 130℃ for 3 to 5 hours.

8. The use of a ruthenium polypyridine complex with a benzenesulfonylindole structure as described in claim 1 in the preparation of anti-Staphylococcus aureus products and / or products for eradicating biofilms formed by Staphylococcus aureus.

9. The use of a ruthenium polypyridine complex with a benzenesulfonylindole structure as described in claim 1 in combination with an antibiotic in the preparation of an anti-Escherichia coli product.

10. The application according to claim 9, characterized in that, The antibiotic in question is polymyxin B.

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