A kind of benzindolium salt and its preparation method and application

Abstract

The present invention discloses a kind of benzindolium salt compound, which has the structure shown in general formula I: #imgabs0#; wherein, R1 is one of H and C1-C6 alkyl, and R2 is one of H, halogen, hydroxyl, nitro, amino, dimethylamine and diphenylamino. Based on the tricyclic structure of carbazole, which is composed of two six-membered benzene rings and a five-membered nitrogen-containing ring, by using its strong electron-donating ability, excellent rigidity and conjugated system, the above-mentioned fragment with strong electron-withdrawing property is introduced through vinyl at the 3-position of the carbazole mother ring by Knoevenagel condensation reaction, so as to achieve the purpose of extending the conjugated system of carbazole; meanwhile, the intramolecular charge transfer (ICT) is enhanced to obtain a longer fluorescence emission wavelength. In addition, the 6-position and 9-position of carbazole are modified to synthesize a series of novel benzindolium salts, which show significant antitumor and antibacterial photodynamic therapy activities.

Description

Technical Field

[0001] The present invention relates to the field of biomedicine technology, and in particular to a benzindolium salt and a preparation method and application thereof. Background Art

[0002] Cancer is one of the leading causes of death worldwide. Tens of millions of people are diagnosed with cancer every year around the world, and more than half of these patients eventually die from cancer. In addition to cancer, there is another invisible threat that has been threatening human health for more than a century: "superbugs" that are resistant to antibiotics. Antimicrobial resistance is becoming more powerful every year, and if appropriate measures are not taken, it is expected to surpass cancer death statistics in the next few decades.

[0003] Cancer and drug-resistant microorganisms have one thing in common: they can both be controlled by photodynamic action. Photodynamic therapy (PDT) was discovered in the 20th century and has received widespread attention in the field of cancer treatment due to its advantages such as less surgical trauma, better selectivity for tumor cells, fewer side effects, and repeatable treatment. In the early 1990s, researchers discovered that simple modifications to this therapy could transform it into a powerful tool for treating microbial infections, which is called antimicrobial photodynamic therapy (aPDT) or photodynamic inactivation of microorganisms (PDI). Today, cancer and infections caused by antibiotic-resistant microorganisms are problems that affect the entire planet. Photodynamic therapy and photodynamic inactivation of microorganisms are alternative methods for treating these diseases. Summary of the invention

[0004] The purpose of the present invention is to solve the defects in the prior art and provide a novel carbazole compound-benzindolinium salt, which has excellent photodynamic properties.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A benzindolium salt, the compound has the structure shown in general formula I:

[0007]

[0008] Among them, R1 is one of H and C1-C6 alkyl, and R2 is one of H, halogen, hydroxyl, nitro, amino, dimethylamine, and diphenylamine.

[0009] The present invention designs drugs for carbazole compounds, introduces a benzene ring into the carbazole skeleton, and then performs ionization treatment to obtain a benzindolium salt, thereby achieving the purpose of extending the carbazole conjugated system; at the same time, intramolecular charge transfer (ICT) is enhanced to obtain a longer fluorescence emission wavelength, and in addition, positions 6 and 9 of carbazole are modified to synthesize a series of novel carbazole compounds, all of which have excellent photodynamic therapy effects.

[0010] In some embodiments, preferably, in the general formula I, R1 is selected from methyl or ethyl; R2 is selected from H, bromine, nitro, amino or diphenylamine.

[0011] In some embodiments, as a preferred example, the preferred structure of the benzindolium salt of the present invention is shown in Table 1 below.

[0012] Table 1 Codes of some compounds of general formula I and their corresponding structures

[0013]

[0014] I1: (E)-2-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide;

[0015] I2: (E)-2-(2-(9-ethyl-6-nitro-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide;

[0016] I3: (E)-2-(2-(6-amino-9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide;

[0017] I4: (E)-2-(2-(6-bromo-9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide;

[0018] I5: (E)-1,1,3-trimethyl-2-(2-(9-methyl-6-nitro-9H-carbazol-3-yl)vinyl)-1H-benzo[e]indole-3-iodine salt;

[0019] I6: (E)-2-(2-(6-(diphenylamino)-9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodine salt.

[0020] The present invention also provides a method for preparing the above-mentioned benzindolium salt, which comprises the following steps: dissolving chemical 1 and compound 2 in anhydrous acetonitrile or anhydrous ethanol, adding piperidine or pyridine as a catalyst, and obtaining the benzindolium salt after the condensation reaction is completed;

[0021] The structural formula of the compound 1 is:

[0022] The structural formula of the compound 2 is:

[0023] The invention introduces a fragment with strong electron-withdrawing property at the 3-position of the carbazole mother ring through a vinyl group through a Knoevenagel condensation reaction, thereby achieving the purpose of extending the carbazole conjugated system.

[0024] In some embodiments, preferably, the condensation reaction is refluxed at 80° C. for 30 min to 12 h.

[0025] More specifically, the preparation method of the benzindolium salt of the present invention is as follows: chemical 1 and compound 2 are dissolved in anhydrous acetonitrile or anhydrous ethanol, 2 drops of piperidine are added, and the mixture is reacted at 80° C. for 30 minutes. After the reaction is completed, the solvent is dried by spin drying, and column chromatography is performed using petroleum ether / dichloromethane (1:2, v / v) as an eluent for purification to obtain the obtained product.

[0026] The present invention also provides the use of the above-mentioned benzindolium salt in the preparation of drugs with photodynamic therapy effects, specifically including the use in tumor treatment and antibacterial.

[0027] The above tumors include colon cancer, liver cancer, lung cancer, breast cancer and cervical cancer. The bacteria include Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The present invention introduces a benzene ring into the carbazole skeleton and then performs ionization treatment to obtain a benzindolium salt, which has high chemical stability under normal conditions and can be stored and used for a long time, making it a reliable photosensitizer that can maintain its activity and performance under light conditions.

[0030] In addition, the present invention modifies carbazole, adjusts its molecular structure, changes its light absorption wavelength and the rate of photosensitization reaction, and obtains a series of novel benzindolium salts, all of which have excellent photodynamic properties.

[0031] The benzindolium salt prepared by the present invention can generate active oxygen molecules, including superoxide anions, etc. after irradiation with light, and can produce type I and type II photodynamic effects; in addition, through the photodynamic therapy activity test on multiple tumor cells and bacteria, it is found that the compound of the present invention can exert a significant synergistic anti-tumor effect of chemotherapy and photodynamic therapy, and significantly inhibit tumor cell proliferation under normoxia or hypoxia, indicating that the compound of the present invention does not rely on oxygen to exert the chemo-photodynamic therapy effect on solid tumors, and can effectively inhibit Staphylococcus aureus and its resistant bacteria, and exert a significant photodynamic antibacterial effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The synthetic route of the benzindolium salt of the present invention is as follows;

[0033] Figure 2 The ultraviolet absorption spectrum (A) and fluorescence spectrum (B) of the compound I1 of the present invention in a 1% DMSO aqueous solution;

[0034] Figure 3 The fluorescence emission spectrum of the compound I1 of the present invention generating superoxide anions (A) and reactive oxygen species (B), the abscissa is the wavelength, and the ordinate is the fluorescence intensity;

[0035] Figure 4 The fluorescence emission spectrum of the compound I2 of the present invention generating superoxide anions (A) and reactive oxygen species (B);

[0036] Figure 5 The fluorescence emission spectrum of compound I3 of the present invention generating superoxide anions (A) and reactive oxygen species (B);

[0037] Figure 6 The fluorescence emission spectrum of compound I4 of the present invention generating superoxide anions (A) and reactive oxygen species (B);

[0038] Figure 7 The fluorescence emission spectra of superoxide anions (A) and reactive oxygen species (B) generated by compound I5 of the present invention;

[0039] Figure 8 This is the fluorescence emission spectrum of active oxygen generated by compound I6 of the present invention. DETAILED DESCRIPTION

[0040] In order to further illustrate the present invention, a series of examples are given below. These examples are purely illustrative and are only used to specifically describe the present invention, and should not be understood as limiting the present invention.

[0041] The preparation method of the benzindolium salt of the present invention is as follows: Compound 1 (1 mmol) and 1,1,2,3-tetramethyl-1H-benzo[e]indole-3-iodine salt (Compound 2, 1 mmol) are dissolved in 25 mL of anhydrous ethanol, 2 drops of piperidine are added for catalysis, and a novel benzindolium salt (general formula I) is obtained through a condensation reaction; the synthetic route is as follows Figure 1 As shown in the figure, R1 is one of H and C1-C6 alkyl, and R2 is one of H, halogen, hydroxyl, nitro, amino, dimethylamine, and diphenylamine.

[0042] Example 1

[0043] Preparation of (E)-2-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodine salt (I1)

[0044] 9-Ethyl-9H-carbazole-3-carboxaldehyde (1 mmol) and 1,1,2,3-tetramethyl-1H-benzo[e]indole-3-iodide (1 mmol) were dissolved in anhydrous ethanol in a 25 mL schlenk tube, 2 drops of piperidine were used as a base, and the reaction was carried out at 80° C. for 30 min. After the reaction was completed, the solvent was dried and column chromatography was performed using petroleum ether / dichloromethane (1:2, v / v) as an eluent to purify and obtain red solid I1 with a yield of 60%.

[0045] The compound spectrum is as follows:

[0046] 1 H NMR (400MHz, DMSO) δ8.90-8.84(m,1H,ArH),8.60-8.50(m,1H,ArH),8.35(m,1H,ArH),8.30(d,J=7.6Hz,1H,ArH),8.17(q ,J=1.9Hz,1H,ArH),8.16-8.11(m,2H,2ArH),7.84(ddd,J=9.0,4.5,2.5Hz,2H,2ArH),7.75(d,J=6.8Hz,1H,ArH),7.72(s ,1H,ArH),7.68-7.61(m,1H,ArH),7.57(td,J=7.6,1.5Hz,1H,ArH),7.46(d,J=7.2Hz,1H,CH=CH),7.39-7.27(m,1H,CH=C H),4.54(q,J=7.0Hz,2H,CH2),4.04(s,3H,CH3),1.92-1.86(m,6H,2CH3),1.37(t,J=7.1Hz,3H,CH3).ESI-MS(m / z):calcd for C 31 H 29 N2+ :429.2325,found429.2316.

[0047] After identification, the structural formula of compound I1 is: (E)-2-(2-(9-ethyl-9H-carbazole-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodine salt.

[0048] Example 2

[0049] Preparation of (E)-2-(2-(9-ethyl-6-nitro-9H-carbazole-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodine salt (I2)

[0050] Referring to the synthesis method of (I1) in Example 1, 9-ethyl-6-nitro-9H-carbazole-3-carbaldehyde was used instead of 9-ethyl-9H-carbazole-3-carbaldehyde in the method to finally obtain red solid I2 with a yield of 68%. 1 H NMR (400MHz, DMSO) δ9.26(d,J=2.3Hz,1H,ArH),9.15(d,J=1.6Hz,1H,ArH),8.61(m,1H,ArH),8. 43(dd,J=9.1,2.3Hz,1H,ArH),8.40-8.35(m,1H,ArH),8.23-8.14(m,3H,3ArH),7.94(dd,J=9.0, 7.3Hz,2H,2ArH),7.86(d,J=8.7Hz,1H,ArH),7.80-7.73(m,2H,2CH=CH),7.66(m,1H,ArH),4.62( q,J=7.3Hz,2H,CH2),3.95(s,3H,CH3),2.42(s,6H,2CH3),1.91(s,3H,CH3).ESI-MS(m / z):calcd for C 31 H 28 N3O2 + :474.2176,found474.2166.

[0051] Example 3

[0052] Preparation of (E)-2-(2-(6-amino-9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodine salt (I3)

[0053] Referring to the synthesis method of (I1) in Example 1, 9-ethyl-6-amino-9H-carbazole-3-carboxaldehyde was used instead of 9-ethyl-9H-carbazole-3-carboxaldehyde to obtain purple solid I3 with a yield of 61%.1 H NMR (400MHz, DMSO) δ8.44(d,J=1.7Hz,1H,ArH),8.18(d,J=8.4Hz,1H,ArH),8.07-8.00(m,2H,2ArH),7.95 (d,J=8.5Hz,1H,ArH),7.88(m,1H,ArH),7.79(d,J=8.5Hz,1H,ArH),7.64-7.58(m,1H,ArH),7.54(d,J=8. 6Hz,1H,ArH),7.49(m,1H,CH=CH),7.40-7.31(m,3H,3ArH),6.87(m,1H,CH=CH),4.94(s,2H,NH2),4.36(q ,J=6.8Hz,2H,CH2),3.96(s,3H,CH3),1.67(s,6H,2CH3),1.30(t,J=7.0Hz,3H,CH3).ESI-MS(m / z):calcd for C 31 H 30 N3 + :444.2434, found 444.2427.

[0054] Example 4

[0055] Preparation of (E)-2-(2-(6-bromo-9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodine salt (I4)

[0056] Referring to the synthesis method of (I1) in Example 1, 6-bromo-9-ethyl-9H-carbazole-3-carboxaldehyde was used instead of 9-ethyl-9H-carbazole-3-carboxaldehyde to obtain a dark red solid (I4) with a yield of 61%. 1H NMR (400MHz, DMSO) δ8.91-8.83(m,1H,ArH),8.35(dd,J=8.4,3.2Hz,1H,ArH),8.30(d,J=7.6Hz ,1H,ArH),8.19-8.10(m,3H,3ArH),7.84(ddd,J=8.9,4.5,2.2Hz,2H,2ArH),7.73(d,J=8.3Hz, 2H,2ArH),7.72(m,2H,2ArH),7.60-7.55(m,1H,CH=),7.36(m,1H,CH=),4.54(q,J=7.1Hz,2H,C H2),4.04(s,3H,CH3),1.92-1.86(m,6H,2CH3),1.37(t,J=7.1Hz,3H,CH3).ESI-MS(m / z):calcd for C 31 H 28 BrN2 + :507.1430, found 507.1421.

[0057] Example 5

[0058] Preparation of (E)-1,1,3-trimethyl-2-(2-(9-methyl-6-nitro-9H-carbazol-3-yl)vinyl)-1H-benzo[e]indole-3-iodine salt (I5)

[0059] Referring to the synthesis method of (I1) in Example 1, 9-methyl-6-nitro-9H-carbazole-3-carbaldehyde was used instead of 9-ethyl-9H-carbazole-3-carbaldehyde to obtain red solid I5 with a yield of 69%. 1 H NMR(400MHz,DMSO)δ9.06(d,J=2.3Hz,1H,ArH),8.95(d,J=1.6Hz,1H,ArH),8.52(m,1H,ArH),8.36-8.15(m,2H,ArH),8.10-8.04(m,3H, 3ArH),7.90(m,2H,2ArH),7.82(d,J=8.7Hz,1H,ArH),7.79-7.71(m,2H,2CH=CH),7.56(m,1H,ArH),3.99(s,3H,CH3),2.09(s,6H,2CH3).

[0060] Example 6

[0061] Preparation of (E)-2-(2-(6-(diphenylamino)-9-ethyl-9H-carbazol-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodine salt (I6)

[0062] Referring to the synthesis method of (I1) in Example 1, 9-ethyl-9H-carbazole-3-carboxaldehyde was replaced by 6-(diphenylamino)-9-ethyl-9H-carbazole-3-carboxaldehyde to obtain a dark red solid (I6) with a yield of 60%. 1 H NMR (400MHz, DMSO) δ8.75(m,1H,ArH),8.71(d,J=1.5Hz,1H,ArH),8.06(d,J=2.0Hz,1H,ArH) ,7.93-8.01(m,2H,2ArH),7.75(m,2H,2ArH),7.69(m,2H,2ArH),7.36(d,J=1.2Hz,1H,ArH), 7.30(d,J=2.2Hz,2H,2ArH),7.22-7.28(m,6H,6ArH),7.09(m,1H,CH=),6.95-7.01(m,5H,4A rH,CH=),4.46(q,J=6.7Hz,2H,CH2),3.92(s,3H,CH3),2.07(s,6H,2CH3),1.43(s,3H,CH3).

[0063] Performance Test Example 1

[0064] Ultraviolet fluorescence spectrum detection of the compounds of the present invention

[0065] The compound I of the present invention was dissolved in water / DMSO solutions of different ratios, and the concentration of the test solution was 20 μM. It was found that it had an obvious ultraviolet absorption peak at 450-550 nm, and the maximum ultraviolet absorption value was at 500 nm. The fluorescence emission spectrum data was tested using a fluorescence spectrometer, and the results showed that the maximum emission wavelength of the compound I1 of the present invention was between 575-625 nm (such as Figure 2 shown).

[0066] Performance Test Example 2

[0067] Test for the ability of the compounds of the present invention to generate active oxygen

[0068] Fluorescence spectroscopy was used to detect the ability of the compound of the present invention to generate active oxygen, using 2,7-dichlorodihydrofluorescein (DCFH) as an active oxygen scavenger. The specific method was to mix the compound of the present invention and a solution of the scavenger DCFH, and then irradiate with laser for a certain period of time. The compound of the present invention was detected at 520nm (100mW / cm 2 )After irradiation with laser, the change of DCFH fluorescence intensity was detected.

[0069] The results show that Figure 3 to Figure 8), the fluorescence intensity of the compounds I1 to I6 of the present invention at about 525 nm increases with the increase of illumination time, indicating that the compounds of the present invention can effectively generate reactive oxygen species after illumination and have the potential for photodynamic therapy.

[0070] Performance Test Example 3

[0071] Test for the ability of the compounds of the present invention to generate superoxide anions

[0072] Fluorescence spectroscopy was used to detect the ability of the compound of the present invention to generate superoxide anions, and dihydroethidium (DHE) was used as a superoxide anion scavenger. The specific method was to mix the compound of the present invention and a solution of the scavenger DHE, and then irradiate with laser for a certain period of time. The compound of the present invention was detected at 520nm (100mW / cm 2 )After irradiation with laser, the change of DHE fluorescence intensity was detected.

[0073] The results show that Figure 3 to Figure 7 ), the maximum fluorescence intensity of compounds I1~I5 increases with the increase of illumination time, indicating that the compounds of the present invention can effectively generate a large amount of superoxide anions after illumination and can play a role in type I photodynamic therapy.

[0074] Performance Test Example 4

[0075] In vitro photodynamic antitumor experiment of the compound of the present invention

[0076] The compounds of the present invention were evaluated for light and dark toxicity by the in vitro toxicity test using the methyl tetrazolium blue colorimetric method (MTT) to study the effect of in vitro photodynamic therapy. First, the dark toxicity was verified by taking human lung cancer cells A549, human liver cancer cells HepG2, human colon cancer cells HT29, human cervical cancer cells Hela and mouse breast cancer cells 4T1 in a good exponential growth phase, digesting and preparing 1×10 4 ~2×10 4 / mL cell suspension, spread on a 96-well plate and keep constant temperature, incubate in the dark for 24 hours, then add the compound of the present invention (10μM), continue to culture for 24 hours, add MTT for 4 hours, discard the supernatant, add a certain amount of DMSO, detect the absorbance at 570nm and calculate the cell survival rate. The photodynamic cell experiment method is basically the same as the above method, add the compound of the present invention and incubate for 1-4 hours, and then observe the absorbance at 520nm (180mW / cm 2 ) after irradiation for 10 minutes, and then cultured for 24 hours. In addition, the 96-well plate with seeded cells was placed in a transparent hypoxic box, and nitrogen protection was used after administration to test the photodynamic activity of the compound of the present invention under hypoxic conditions. Finally, MTT was added to the 96-well plate and reacted in an incubator for 4 hours. The absorbance of each well was measured at a wavelength of 450nm using an enzyme-linked immunosorbent assay, and the cell proliferation inhibition rate was calculated.

[0077] The compounds of the present invention were subjected to a series of tumor cell anti-proliferation activity tests. The experimental results show (Table 2 and Table 3) that under normoxic and hypoxic conditions, compounds I1, I2, I3, I4, I5 and I6 of the present invention have certain inhibitory activity on the proliferation of HepG2, A549, HT29, Hela and 4T1 tumor cells, and the inhibitory activity on the above tumor cells is significantly enhanced after illumination, exerting a significant chemical / photodynamic therapeutic effect on tumor cells; in addition, the compounds of the present invention have oxygen-independent photodynamic therapy properties, can be used for the treatment of solid tumors under hypoxia, provide a new method for clinical tumor treatment, and have broad application prospects.

[0078] Table 2 Inhibition rate of some compounds of the present invention on tumor cells under normoxic conditions % (10 μM)

[0079]

[0080] ND: Not tested.

[0081] Table 3 Inhibition rate of some compounds of the present invention on tumor cells under hypoxic conditions (10 μM)

[0082]

[0083] ND: Not tested.

[0084] Performance Test Example 5

[0085] In vitro photodynamic antibacterial experiment of the compounds of the present invention

[0086] The antibacterial activity of Staphylococcus aureus (S.aureus) and methicillin-resistant Staphylococcus aureus (MRSA) was evaluated by broth microdilution method (turbidimetry). Nutrient broth medium (LB) was used to prepare a two-fold diluted drug suspension. In a 96-well plate, 100 μL of the diluted bacterial suspension and 100 μL of the compound solution of the present invention (10 μM) were added to each well, and the final control volume per well in the 96-well plate was 200 μL. After illumination, the plate was incubated at 37°C for 16 hours. The bacterial survival rate was indicated by observing the turbidity and comparing it with the control, measuring its absorbance at 450nm, and the ratio between it and the blank group.

[0087] Table 4 Effect of some compounds of the present invention on bacterial survival rate (10 μM)

[0088]

[0089] ND: Not tested.

[0090] As shown in Table 4 above, the compounds of the present invention have different degrees of antibacterial activity against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus at a concentration of 10 μM, and the bacterial survival rate of the compounds of the present invention is significantly reduced under light conditions, showing a strong photodynamic antibacterial effect.

Claims

1. A benzindolium salt having a structure shown in general formula I: in, R1 is one of H and C1-C6 alkyl, and R2 is one of halogen, hydroxyl, nitro, amino, dimethylamino and diphenylamino.

2. The benzindolium salt according to claim 1, characterized in that In the general formula I, R1 is selected from methyl or ethyl; R2 is selected from bromine, nitro, amino or diphenylamino.

3. The benzindolium salt according to claim 2, characterized in that: The benzindolium salt is (E)-2-(2-(9-ethyl-6-nitro-9H-carbazole-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide, (E)-2-(2-(6-amino-9-ethyl-9H-carbazole-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide, (E)-2-(2-(6-amino-9-ethyl-9H-carbazole-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide, )vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide, (E)-1,1,3-trimethyl-2-(2-(9-methyl-6-nitro-9H-carbazole-3-yl)vinyl)-1H-benzo[e]indole-3-iodide, (E)-2-(2-(6-(diphenylamino)-9-ethyl-9H-carbazole-3-yl)vinyl)-1,1,3-trimethyl-1H-benzo[e]indole-3-iodide.

4. The method for preparing the benzindolium salt according to any one of claims 1 to 3, characterized in that: The preparation method of the benzindolium salt comprises the following steps: dissolving compound 1 and compound 2 in anhydrous acetonitrile or anhydrous ethanol, adding piperidine or pyridine as a catalyst, and obtaining the benzindolium salt after the condensation reaction is completed; The structural formula of the compound 1 is: The structural formula of the compound 2 is: Among them, R1 is one of H and C1-C6 alkyl, and R2 is one of halogen, hydroxyl, nitro, amino, dimethylamino and diphenylamino.

5. The method for preparing the benzindolium salt according to claim 4, characterized in that: The condensation reaction is refluxed at 80° C. for 0.5 to 12 hours.

6. The method for preparing the benzindolium salt according to claim 5, characterized in that: After the condensation reaction is completed, the benzindolium salt is purified by column chromatography or recrystallization.

7. The method for preparing the benzindolium salt according to claim 6, characterized in that: The column chromatography uses a petroleum ether / dichloromethane mixture with a volume ratio of 1:2 as an eluent to purify the benzindolium salt.

8. Use of the benzindolium salt according to any one of claims 1 to 3 in the preparation of a drug having a photodynamic therapy effect.

9. Use of the benzindolium salt according to any one of claims 1 to 3 in the preparation of drugs for resisting Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

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