Application of isoliensinine in preparation of medicine for treating staphylococcus aureus infectious arthritis

Abstract

The invention discloses an application of isoliensinine in preparation of a medicine for treating staphylococcus aureus infectious arthritis. According to a treatment model of SD rat staphylococcus aureus infectious arthritis, the isoliensinine is proved to be capable of improving excessive inflammatory response of joint tissues infected by staphylococcus aureus and remarkably relieving pathological injury of rat joints, and the isoliensinine has a relatively good treatment effect on staphylococcus aureus infectious arthritis. In addition, the invention reveals that the isoliensinine is combined with a staphylococcus aureus reaction regulatory factor SaeR in a targeted manner, so that the toxicity of staphylococcus aureus is reduced to play a role. Compared with the traditional antibiotic for treating staphylococcus aureus, the isoliensinine has the advantages of no survival pressure on germs and no generation of drug resistance of the germs. Therefore, the isoliensinine has a relatively good potential application prospect in research and development of safe and effective medicines for treating the staphylococcus aureus infectious arthritis.

Description

Technical Field

[0001] The invention relates to the technical field of medicines, and in particular to application of isoliensinine in preparing a medicine for treating Staphylococcus aureus infectious arthritis. Background Art

[0002] Staphylococcus aureus is an important Gram-positive pathogen that mainly exists in the skin and mucous membranes. About 30% of healthy adults are carriers of Staphylococcus aureus. It can cause suppurative infections of the skin and soft tissues of humans and animals, arthritis, pericarditis, and a variety of infectious diseases such as sepsis and septicemia, and even death. It has the significant characteristics of high morbidity, high mortality and high treatment costs, and has become a serious public health safety issue facing the world. Among them, Staphylococcus aureus infectious arthritis is a disease mediated by Staphylococcus aureus. Once infected, if it is not treated in time, it is easy to cause irreversible damage to the joints. The disease has high disability and mortality rates and severe drug resistance. Timely diagnosis and treatment are needed to save the patient's life and irreparable joint degeneration.

[0003] The pathogenicity of S. aureus is closely related to its virulence factors, and the Sae system plays a crucial role as a central downstream regulator. It is a two-component system composed of histidine kinase (SaeS) and response regulator (SaeR). As a downstream regulator in the Sae two-component system, SaeR can regulate many downstream dominant virulence genes, including hla (encoding α-hemolysin), hlb (encoding β-hemolysin), cna (encoding coagulase), eap (encoding extracellular adhesion protein) and fnbA (encoding fibronectin binding protein A), affecting the purine synthesis pathway, pyrimidine biosynthesis pathway, arginine deiminase pathway, etc. Therefore, SaeR is a potential target for the development of anti-virulence drugs for S. aureus infection.

[0004] Due to the evolution of Staphylococcus aureus itself and the abuse of antibiotics, drug-resistant strains of Staphylococcus aureus (such as methicillin-resistant Staphylococcus aureus, MRSA) continue to emerge. At the same time, due to the difficult-to-treat and easy-to-relapse characteristics of Staphylococcus aureus infectious arthritis itself, the therapeutic performance of traditional antibacterial drugs on Staphylococcus aureus infectious arthritis has declined. Therefore, there is an urgent need to develop new anti-infective drugs based on new drug targets that can safely and effectively control infection while avoiding the development of bacterial resistance.

[0005] Isoliensinine, chemical formula is C 37 H 42 N2O6 is a dibenzylisoquinoline alkaloid extracted from lotus seed embryos. Its molecular structure is as follows Figure 1 As shown, it has antioxidant, anti-inflammatory and anti-cancer activities. However, there is no report on the use of isoliensinine in the treatment of Staphylococcus aureus-induced arthritis at home and abroad. Summary of the invention

[0006] The present invention discovers for the first time that isoliensinine can directly inhibit the activity of SaeR of Staphylococcus aureus, thereby significantly reducing the virulence of Staphylococcus aureus and having a good protective effect on Staphylococcus aureus infectious arthritis.

[0007] Specifically, the present invention discloses the use of isoliensinine in the preparation of medicines for treating Staphylococcus aureus infectious diseases.

[0008] Furthermore, the present invention discloses the use of isoliensinine in the preparation of a drug for treating Staphylococcus aureus-infected arthritis.

[0009] Furthermore, the present invention discloses the use of isoliensinine in the preparation of a drug for treating methicillin-resistant Staphylococcus aureus infectious arthritis.

[0010] The invention discloses application of isoliensinine in preparing a drug for inhibiting SaeR of Staphylococcus aureus.

[0011] In the present invention, isoliensinine can be used as an active ingredient and pharmaceutically acceptable excipients to prepare various pharmaceutically acceptable dosage forms, such as capsules, injections or tablets, which are well known to those skilled in the art, and the present invention is not limited thereto.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The present invention discloses for the first time that isoliensinine reduces the pathogenicity of Staphylococcus aureus by inhibiting the activity of SaeR, thereby significantly reducing the invasive effect of bacteria on host cells. Different from the mechanism of action of antibiotics, isoliensinine does not put pressure on the survival of bacteria, and thus does not cause the development of drug resistance. The present invention applies isoliensinine to the inhibition of SaeR, a response regulator of Staphylococcus aureus, and discloses a new use of isoliensinine in the preparation of drugs related to the inhibition of SaeR.

[0014] 2. The present invention discloses the application of isoliensinine in treating Staphylococcus aureus infectious arthritis. In vivo experiments show that the use of isoliensinine to treat Staphylococcus aureus infectious arthritis can significantly reduce the histopathological damage of rat MRSAUSA300 infectious arthritis. The present invention provides a reliable basis for the treatment of Staphylococcus aureus infectious arthritis with isoliensinine, opens up a new way for the development of new therapeutic drugs, and also lays a certain foundation for the development of similar traditional Chinese medicines. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0016] Figure 1 is the molecular structural formula of isoliensinine;

[0017] Figure 2 The figure shows the effect of isoliensinine on the growth of Staphylococcus aureus and the biosafety verification results; in the figure, (a) is the growth curve measurement result, (b) is the minimum inhibitory concentration (MIC) measurement result, (c) is the cell viability measurement result, (d) is the in vivo toxicity test result of the greater wax moth, and (e) is the hemolytic activity test result of isoliensinine.

[0018] Figure 3 The results show that isoliensinine can inhibit the activity of SaeR of Staphylococcus aureus in a targeted manner. In the figure, (a) is the result of intracellular thermal stability experiment (CETSA), and (b) is the result of surface plasmon resonance analysis (SPR).

[0019] Figure 4 The results of a study on the ability of isoliensinine to inhibit the internalization of Staphylococcus aureus into embryonic carcinoma cell-derived chondroid cell line 5 (ATDC5 cells); in the figure, (a) is the fluorescence staining result of Staphylococcus aureus internalizing ATDC5 cells, (b) is the plate colony count and quantitative result of Staphylococcus aureus internalizing ATDC5 cells, and (c) is the result of neutrophil chemotaxis experiment.

[0020] Figure 5 These are the Micro-CT results of isoliensinine alleviating knee joint damage in rats with Staphylococcus aureus infectious arthritis; in the figure, (a) is the Micro-CT three-dimensional reconstruction and typical results, and (b) is the quantitative results of tissue mineral density (TMD), trabecular bone and condylar cortex BV fraction (BV / TV).

[0021] Figure 6 This is a diagram showing the pathological results of the protective effect of isoliensinine on the knee joint tissue of rats with Staphylococcus aureus-induced arthritis.

[0022] The significance analysis symbols involved in each figure are: NS: no significant difference, *: P≤0.05, **: P≤0.01, ***: P≤0.001. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present invention.

[0024] The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0025] Unless otherwise specified, the test materials used in the following examples were purchased from conventional biochemical reagent stores.

[0026] The Staphylococcus aureus MRSA USA300 used in the present invention was purchased from the American Type Culture Collection (ATCC, Manassas, VA), and is a highly pathogenic and drug-resistant Staphylococcus aureus strain originally discovered in the U.S. It is a representative strain of community-acquired MRSA (CA-MRSA) and is one of the main pathogens causing skin and soft tissue infections worldwide.

[0027] The SaeR knockdown strain group was constructed by our laboratory using existing technology (reference Chen, W., et al., Rapid and Efficient Genome Editing in Staphylococcus aureus by Using an Engineered CRISPR / Cas9 System. J Am Chem Soc, 2017. 139(10): p. 3790-3795.).

[0028] The application of isoliensinine provided by the present invention in the preparation of a drug for treating methicillin-resistant Staphylococcus aureus infectious arthritis is described in detail below in conjunction with the examples.

[0029] Example 1 Effect of isoliensinine on the growth of Staphylococcus aureus and biosafety verification

[0030] 1.1 Growth assay: Overnight culture of S. aureus USA300 (ATCC, Manassas, VA) was diluted 1:100 and transferred to fresh BHI medium with or without 64 μg / ml isoliensinine and cultured to OD600 of 0.3. The bacterial solution was divided into TSB group (TSB medium control), control group (S. aureus), drug group (S. aureus + isoliensinine (64 μg / ml)) and SaeR knockdown strain group (laboratory construction). OD was measured at 1 hour intervals within 24 hours using a microplate reader. 600 nm absorbance, and further plotted the growth curve.

[0031] 1.2 Minimum inhibitory concentration (MIC): The MIC value of isoliensinine against S. aureus USA300 was determined by the microbroth dilution method. The bacterial culture was inoculated into fresh CAMHB medium at a dilution ratio of 1:1000 and cultured to the logarithmic phase. In a 96-well plate, 100 μl CAMHB, 1×10 5CFU) as the control group (referred to as the S. aureus group), a series of isoliensinine concentrations (1 to 256 μg / ml) were prepared, including a blank medium control group. After incubation at 37°C for 16 hours, the MIC was determined as the lowest drug concentration at which bacterial growth was not visible to the naked eye.

[0032] 1.3 Cell viability: 2×10 4 Embryonic carcinoma cell-derived chondroid cell line 5 (ATDC5 cells) were seeded in a 96-well plate at 37°C and 5% CO2 for 24 hours. Then, different concentrations of isoliensinine (4 to 64 μg / ml) were added and maintained for another 24 hours. After discarding the culture medium, 0.5 mg / ml of MTT solution was added to the 96-well plate and incubated for 4 hours, and the crystals were dissolved with DMSO. A blank group (control) was set at the same time. The absorbance value at 490 nm was measured with an ELISA reader.

[0033] 1.4 In vivo toxicity test of greater wax moth: The final-instar larvae of greater wax moth (weight 220–260 mg) were raised in an environment of 37°C. They were divided into 4 groups using a random number table method, with 5 in each group, namely the blank group (control), the control group (DMSO) and the isoliensinine (20, 40 mg / kg) treatment group. The treatment group was injected with a 10μl Hamilton syringe, and the control group was injected with an equal dose of PBS containing 0.1% DMSO. The injection site was the last hole of the right leg of each larva. In the following 5 days, the survival status and degree of melanization of the larvae in each group were evaluated and recorded.

[0034] 1.5 Hemolytic activity of isoliensinine: Centrifuge fresh defibrinated rabbit red blood at 4°C, 4000rpm for 3 minutes, discard the supernatant, and repeat this step until the supernatant is transparent and colorless. Then, add 0.5ml of PBS to each test tube and resuspend the red blood cells. Set up a negative control using PBS and a positive control adding Triton X-100. Add different concentrations of isoliensinine (8 to 128μg / ml) to the remaining test tubes. After incubation at 37°C, centrifuge and collect the supernatant at OD 600 Measure its optical density.

[0035] The results are as follows Figure 2 There was no significant difference in the growth rate of S. aureus between the S. aureus + isoliensinine (64 μg / ml) group and the S. aureus group. Figure 2 As shown in (a). We used the microdilution method to determine that the MIC of isoliensinine against S. aureus USA300 was 256 μg / ml. This means that isoliensinine does not inhibit the growth of S. aureus USA300, which is consistent with the expected properties of anti-virulence drugs, such as Figure 2In addition, the cytotoxicity experiment showed that even at a concentration of 64 μg / ml, isoliensinine did not have an adverse effect on the survival of ATDC5 cells, proving its biosafety. Figure 2 Subsequently, we extended the evaluation of isoliensinine toxicity in vivo using G. mellonella larvae, and we observed no mortality in G. mellonella larvae in all groups. The results showed that both 20 and 40 mg / kg doses of isoliensinine were well tolerated, as shown in Figure 2. Figure 2 As shown in (d). No obvious drug hemolytic activity was found by adding isoliensinine at a concentration of up to 128 μg / ml. Figure 2 These findings provide a solid foundation for further exploring isoliensinine as a potential anti-toxic drug.

[0036] Example 2 Targeted inhibition of SaeR activity of Staphylococcus aureus by isoliensinine

[0037] 2.1 Intracellular thermostability assay (CETSA): After ultrasonic disruption of the bacterial suspension, the supernatant was collected by centrifugation, one part of which was treated with isoliensinine (64 μg / ml) and the other part was treated with DMSO as a control. The mixture was incubated at 37°C for 1 hour. After incubation, the supernatant was obtained by centrifugation and distributed into PCR tubes, and then incubated for 5 minutes at a specific temperature for SaeR protein and quickly ice-bathed for 3 minutes. The sample was then mixed with protein loading buffer and separated by electrophoresis using 12% SDS-PAGE.

[0038] 2.2 Surface Plasmon Resonance Analysis (SPR): The interaction between isoliensinine and SaeR was analyzed by Open SPR instrument. SaeR protein was diluted in binding buffer (10mM HEPES, 120mM NaCl, 3mM EDTA, 0.005% Tween 20, pH7.4), and isoliensinine was diluted in 1% DMSO in PBS solution to 100μmol / L, 50μmol / L, 25μmol / L, 12.5μmol / L, 6.25μmol / L, 3.125μmol / L, 1.56μmol / L, 0.78μmol / L, and 0.39μmol / L. After equilibrating the signal with 1% DMSO in PBS solution, imidazole and NiCl2 solution were added to complete the functionalization of the chip surface. After that, the SaeR protein was fixed on the chip, with a protein-ligand binding time of 240 s and a natural dissociation of 240 s. After the signal was smoothed, different concentrations of isoliensinine were added to confirm the maximum binding force of the surface. The results were analyzed by TraceDrawer and One To One.

[0039] The results are as follows Figure 3We conducted CETSA experiments to verify that as the temperature increased, there was a significant difference between the isoliensinine treatment group and the DMSO treatment group, which indicated that there was a direct interaction between isoliensinine and SaeR. Figure 3 As shown in (a). SPR can respond to the kinetic processes of binding, dissociation and molecular recognition between drug molecules and target proteins in their natural state. We verified the binding behavior of isoliensinine with SaeR in SPR analysis. The results are shown in Figure 3 As shown in (b), the higher the concentration of isoliensinine, the greater the protein-ligand surface binding force. In the protein-protein interaction hierarchy, the affinity constant (KD) value calculated by SPR analysis is 3.34×10 -5 M, The results showed that SaeR and isoliensinine had a very strong binding ability.

[0040] Example 3 Isolysinine inhibits the internalization of Staphylococcus aureus into embryonic carcinoma cell-derived chondrogenic cell line 5 (ATDC5 cells) and enhances neutrophil chemotaxis

[0041] 3.1 Fluorescence staining of intracellular bacteria: The experiment was divided into 5 groups: control group (simple ATDC5 cells), infection group (ATDC5 cells infected with S. aureus), isoliensinine (32 μg / ml), isoliensinine (64 μg / ml) and SaeR knockdown strain group (referred to as SaeR knockdown group). S. aureus was incubated with different concentrations of isoliensinine (32 and 64 μg / ml) at 37°C for 24 hours, and the same concentration of DMSO (0.1%) was added to the other groups, and 5(6)-FAM SE was used to label the bacteria. ATDC5 cells were incubated at 2×10 5 Cells were seeded at a density of 1×10 cells / well in a 24-well plate in DMEM medium containing 10% fetal bovine serum. 5 ATDC5 cells were infected with S. aureus at 50 μg / ml for 1 hour. After treatment with 50 μg / ml gentamicin for 1 hour, the cells were washed three times with sterile PBS. The cells were fixed with 4% paraformaldehyde for 15 minutes, permeabilized with PBS containing 0.1% Triton X-100 for 10 minutes, and then stained with TRITC phalloidin and DAPI. Images were collected using a fluorescence microscope.

[0042] 3.2 Cell invasion assay: The experiment was divided into 4 groups, namely infection group (ATDC5 cells infected with S. aureus), isoliensinine (32 μg / ml) group, isoliensinine (64 μg / ml) group and SaeR knockdown strain group (referred to as SaeR knockdown group). ATDC5 cells were cultured at 2×10 5Cells / well were inoculated in 24-well plates and incubated overnight (37°C, 5% CO2). Staphylococcus aureus USA300 with different final concentrations of isoliensinine (32 and 64 μg / ml) was incubated at 37°C, 200rpm until OD600 reached 1.0. USA300 and SaeR knockdown strains were set as positive and negative controls, respectively. Then, 400 μl of bacterial solution was added to a 24-well plate and cultured in a 37°C biochemical incubator for 2 hours. After washing 3 times with PBS, 1 ml of high-glucose DMEM supplemented with 300 μg / ml gentamicin was added and incubated at 37°C for 1 hour. The ATDC5 cells on the coverslip were then lysed with 1% Triton X-100 for 30 minutes and then inoculated onto BHI broth agar plates for colony counting. The relative number of internalized bacteria was calculated as CFU / total number of ATDC5 cells.

[0043] 3.3 Neutrophil chemotaxis: The experiment was divided into 5 groups, namely control group (negative control group), infection group (Staphylococcus aureus), isoliensinine (32μg / ml) group, isoliensinine (64μg / ml) group and SaeR knockdown strain group (SaeR knockdown group). The neutrophils were resuspended in HBSS containing 1% BSA. The SaeR knockdown strain or Staphylococcus aureus USA300 was incubated at 37°C and 220rpm for 4 hours in the presence of different concentrations of isoliensinine. Subsequently, the supernatant was separated and the bacteria were inactivated by exposing them to a temperature of 60°C for 30 minutes. The migration of neutrophils was evaluated using a 24-well plate and a transwell insert with a pore size of 3.0μm. The inactivated bacteria (at a concentration of 3×10 8 CFU / insert) were placed in these inserts, and 0.6 ml of HBSS containing 1% BSA occupied the lower chamber. Neutrophils were exposed to the above bacterial supernatant for 30 minutes at 37°C, after which they were centrifuged and redispersed in HBSS containing 1% BSA. Subsequently, a concentration of 1.5×10 4 Neutrophils were incubated for 1 hour, and cells that failed to migrate were discarded. Neutrophils were then stained with Alexa Fluor 647-conjugated Ly6G, washed three times with sterile PBS, and the emitted fluorescence was measured at wavelengths of 535 nm and 488 nm.

[0044] The results are as follows Figure 4 We first evaluated the ability of untreated and isoliensinine-treated S. aureus to invade cells. We observed that after isoliensinine treatment, the internalization of S. aureus into ATDC5 cells was reduced, and the ability of isoliensinine to inhibit the internalization of S. aureus was dose-dependent. It is worth noting that the ability of the SaeR knockdown strain to internalize cells was significantly weakened, as shown in Figure 2. Figure 4As shown in (a). The CFU count results of intracellular S. aureus colonies confirmed that isoliensinine can limit the invasion of S. aureus, and the effect is concentration-dependent. Consistent with the results of intracellular fluorescence staining, the CFU count of intracellular colonies in the SaeR knockdown strain group was significantly reduced, as shown in Figure 2. Figure 4 In addition, the supernatant of Staphylococcus aureus significantly inhibited chemotaxis, and the chemotaxis assay of rat neutrophils treated with isoliensinine further confirmed that this inhibitory effect weakened with the increase of isoliensinine concentration. The ability of the supernatant of the SaeR knockdown strain to inhibit neutrophil chemotaxis was significantly weakened, as shown in Figure 2. Figure 4 These findings indicate that SaeR of S. aureus plays a crucial role in the internalization of S. aureus into cells and immune evasion, and that isoliensinine can protect host cells from the harmful effects induced by USA300 and enhance the chemotaxis of neutrophils, thereby increasing the sensitivity of host immunity to S. aureus.

[0045] Example 4 Experimental therapeutic study of isoliensinine on Staphylococcus aureus-induced arthritis

[0046] 4.1 Establishment of the rat Staphylococcus aureus infectious arthritis model

[0047] Methods: Male SD rats (6–8 weeks old) were divided into 4 groups (infection group, vancomycin (20 mg / kg) group, isoliensinine (40 mg / kg) group, and control group), with 3 rats in each group. Isoflurane inhalation anesthesia was used. The fur around the knee joint was removed using a shaver and gently cleaned with warm water. The knee joint skin was disinfected with povidone-iodine cotton balls and isopropyl alcohol cotton balls. MRSA USA300 (4×10 6 CFU / 10μl) after infecting the knee joint, vancomycin (20mg / kg) or isoliensinine (40mg / kg) was injected subcutaneously with a U-100 insulin syringe once a day for 6 days. The control group animals were injected with the same volume of saline. Then, all rats were placed on a warming pad and monitored to be able to walk. All rats were housed in groups in ventilated cages at 22±3℃ and fed food and water freely. After the observation period, the rats were euthanized by placing them in a carbon dioxide chamber, and the chamber was filled with carbon dioxide at a low rate, accounting for 30% of the chamber volume every minute.

[0048] 4.2 Micro-CT results of isoliensinine alleviating knee joint injury in rats with Staphylococcus aureus-induced arthritis

[0049] The ex vivo knee joint tissues of rats in each group were fixed with 10% buffered formalin for 5 days, then transferred to 70% ethanol and stored at 4°C. Micro-CT analysis of the femoral and tibial condyles of the rat knee joints was performed using the NEMO Micro CT system. The voltage was set to 80 kV, the current was set to 0.06 mA, and the scanning time was 200 s. Recon software was used for three-dimensional image reconstruction. The smoothness of the cartilage surface and the degree of subchondral bone sclerosis were examined in the coronal and sagittal planes, respectively. After three-dimensional reconstruction, Cruiser software was used to collect data. The tissue mineral density (TMD), tissue volume (TV), and bone volume (BV) of the condylar cortex were directly measured, and the BV fraction of trabecular bone to condylar cortex (BV / TV) was calculated.

[0050] The results are as follows Figure 5 Micro-CT studies the joint structure in the context of infection. Three-dimensional images showed significant erosion of the cortical and cancellous bone of the subchondral bone of the distal femur and proximal tibia of MRSA-infected rats, and increased hyperplastic bone (a sign of reactive bone formation in the subacute or chronic phase) in the femur and tibia, as shown in Figure 2. Figure 5 (a) As shown. During MRSA infection, the bone volume / total volume (BV / TV) and tissue mineral density (TMD) of the cortical and cancellous bones of the femur and tibia were both low. Treatment with vancomycin or isoliensinine alone could improve the changes in BV / TV caused by MRSA, as shown in Figure 2. Figure 5 (b) as shown.

[0051] 4.3 Pathological results of the protective effect of isoliensinine on knee joint tissues in rats with Staphylococcus aureus-induced arthritis

[0052] The knee joints of rats in each group were isolated after euthanasia, first fixed with 4% paraformaldehyde, then decalcified with 12% EDTA, embedded in paraffin, and cut into 4 μm thickness for safranin-fast green (SAF O) staining. Images of stained knee joint tissues were captured under an optical microscope.

[0053] The results are as follows Figure 6 As shown, SAF O staining revealed severe inflammatory exudate and necrotic areas in the infection group. In contrast, we observed milder inflammatory responses in the vancomycin and isoliensinine treatment groups. In addition, SAF O staining in the vancomycin and isoliensinine treatment groups showed that vancomycin and isoliensinine treatment could improve MRSA-induced cartilage degradation, bone erosion, and bone formation, highlighting the joint protective effect of isoliensinine treatment in the setting of bacterial synovial joint infection.

[0054] In summary, isoliensinine inhibits the activity of SaeR of S. aureus, reduces its pathogenicity, significantly reduces the invasion of bacteria on host cells, and increases the sensitivity of host immunity to S. aureus. More importantly, in the validation of the rat model of S. aureus infectious arthritis, the introduction of isoliensinine can improve MRSA-induced joint damage, further confirming that this benefit is attributed to its anti-toxic properties. Isoliensinine has the potential to be developed into a safe and effective anti-toxic drug with potential clinical application value. At the same time, because it binds to the SaeR protein, it shows that SaeR is an attractive druggable target for S. aureus infection.

[0055] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. The application of isoliensinine in the preparation of drugs for treating Staphylococcus aureus infectious diseases.

2. The use according to claim 1, characterized in that: The Staphylococcus aureus is methicillin-resistant Staphylococcus aureus.

3. The use according to claim 2, characterized in that: The methicillin-resistant Staphylococcus aureus is Staphylococcus aureus USA300.

4. The use according to claim 1, characterized in that: The Staphylococcus aureus infectious disease is Staphylococcus aureus infectious arthritis.

5. The use according to claim 4, characterized in that: The Staphylococcus aureus infectious arthritis is methicillin-resistant Staphylococcus aureus infectious arthritis.

6. Application of isoliensinine in the preparation of drugs that inhibit the activity of SaeR protein of Staphylococcus aureus.

7. A drug for treating Staphylococcus aureus infectious diseases, characterized in that: The drug reduces the toxicity of MRSA by inhibiting the activity of SaeR protein in MRSA. The drug is prepared into a pharmaceutically acceptable dosage form with isoliensinine as an active ingredient and pharmaceutically acceptable excipients.

8. The drug for treating Staphylococcus aureus infectious diseases according to claim 7, characterized in that: The dosage form of the drug includes but is not limited to tablets, capsules and injections.

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