Quaternized β-carboline compound, pharmaceutical composition and antibacterial use thereof

Abstract

The present invention relates to the field of antimicrobial agents, and in particular to quaternized β-carboline compounds, pharmaceutical compositions thereof, and antimicrobial uses. The present invention provides a quaternized β-carboline compound, the MIC value of which against MRSA is 0.25 to 1 μg / mL, which is stronger than the clinical first-line drug vancomycin, and can be used to treat infectious diseases caused by MRSA such as bacteremia, pneumonia, myocarditis, wound infection, bone and joint infection, etc., and can provide more options for solving the increasingly serious problem of MRSA resistance.

Description

Technical Field

[0001] The present invention relates to the field of antimicrobial agents, and in particular to a quaternized β-carboline compound, a pharmaceutical composition thereof and antimicrobial use thereof. Background Art

[0002] Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important pathogens in nosocomial and community infections worldwide. It has the characteristics of high morbidity, high mortality, and difficult treatment. It can cause bacteremia, pneumonia, myocarditis, wound infection, bone and joint infection, etc., which seriously threatens human health. At present, general antibiotics such as cefazolin and cefuroxime are usually used for treatment in clinical practice. When the effect is not good, antibacterial drugs with higher sensitivity such as vancomycin and linezolid are selected. However, with the increasing severity of MRSA resistance, the emergence of resistant strains such as new drugs on the market such as daptomycin, and the continuous decline in the number of newly approved related drugs, it is urgent to discover new anti-MRSA drugs for clinical treatment.

[0003] Studies have found that the combination of single-target drugs or multi-target drugs can effectively overcome the occurrence and development of bacterial resistance. Compared with the combination of single-target drugs, multi-target drugs have better therapeutic effects, lower risk of drug interactions and toxic side effects, and more predictable pharmacokinetic properties, and have gradually become the mainstream choice for antibacterial drug research and development. Of the 27 antibacterial drugs approved by the US FDA in the past 20 years, 14 have multi-target mechanisms of action.

[0004] β-Carboline has anti-MRSA activity and can act on multiple intracellular targets such as DNA and DNA gyrase. CN105481855B discloses a β-carboline compound: a 2-aryl-3,4-dihydro-β-carboline salt compound, which is used to prepare a plant antibacterial agent. CN111393438B discloses a 6-substituted-β-carboline base compound and derivatives, as well as their use in pesticide fungicides. However, the β-carboline compounds reported in the above literature are mostly used for agricultural antibacterial.

[0005] Quaternary ammonium salt compounds have the amphiphilic and positively charged properties of traditional antimicrobial peptides, can act on bacterial cell membranes, are not prone to drug resistance, and can also solve the defects of traditional antimicrobial peptides such as high production costs and easy inactivation by proteases. Natural products have always been an important source for the discovery of antimicrobial drugs due to their diversity of chemical structures and targets. In the past four decades, natural products and their derivatives account for about half of the antimicrobial drugs approved worldwide. If the advantages of natural product β-carboline and quaternary ammonium salts are integrated, and new quaternized β-carboline compounds with multi-target action mechanisms are designed through molecular hybridization strategies, it will be of great significance for the development and clinical treatment of anti-MRSA drugs. In previous studies, the inventors synthesized a quaternized β-carboline dimer compound with high anti-MRSA activity, but there is still a gap compared with vancomycin, and it needs to be further improved to improve the anti-MRSA activity. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a quaternized β-carboline compound, which has stronger anti-MRSA activity than the clinical first-line drug vancomycin, and can be used to treat infectious diseases caused by MRSA such as bacteremia, pneumonia, myocarditis, wound infection, bone and joint infection, etc., and can provide more options for solving the increasingly serious problem of MRSA resistance.

[0007] The first aspect of the present invention provides a quaternized β-carboline compound, the general structural formula of which is shown in Formula I:

[0008] Wherein n is a positive integer greater than or equal to 9.

[0009] In some embodiments, n is a positive integer from 9 to 20. For example, n can be 9, 10, 11, 12, 13, 15, 15, 16, 17, 18, 19, 20, etc.

[0010] The second aspect of the present invention provides a method for preparing the quaternized β-carboline compound, which is prepared by the following reaction route:

[0011]

[0012] In some embodiments, the preparation method comprises the following steps:

[0013] (i) dissolving tryptamine in a glacial acetic acid / methanol solution, adding an acetaldehyde aqueous solution, and heating to react to obtain compound 2;

[0014] (ii) Compound 2 is mixed with palladium on carbon and added into xylene, and heated to react to obtain Compound 3;

[0015] (iii) dissolving compound 3 in anhydrous N,N-dimethylformamide, adding sodium hydride in an ice bath and stirring, and then adding dibromo long-chain alkyl to react to obtain compound 4;

[0016] (iv) Compound 4 is dissolved in acetonitrile, methyl iodide is added, and the mixture is heated and stirred to react to obtain Compound 5, which is the quaternized β-carboline compound.

[0017] The carbon chain length of the dibrominated long-chain alkyl group is greater than or equal to C9, such as C9, C12, and C20; the dibrominated long-chain alkyl group is 1,9-dibromononane, 1,10-dibromodecane, 1,11-dibromonoundecane, 1,12-dibromodecane, and the like.

[0018] The third aspect of the present invention provides the use of the quaternized β-carboline compound for preparing an anti-MRSA (methicillin-resistant Staphylococcus aureus) drug.

[0019] The fourth aspect of the present invention provides an anti-MRSA pharmaceutical composition comprising the quaternized β-carboline compound and pharmaceutical excipients.

[0020] In some embodiments, the pharmaceutical composition can be used to treat infectious diseases caused by MRSA, such as bacteremia, pneumonia, myocarditis, wound infection, bone and joint infection, etc.

[0021] Compared with the prior art, the beneficial effects of the present invention include at least:

[0022] The quaternized β-carboline compound of the present invention has a novel structure, and compared with the existing β-carboline compounds or quaternized β-carboline compounds, the anti-MRSA activity is greatly improved, the MIC value is 0.25-1 μg / mL, which is stronger than the clinical first-line drug vancomycin, and is effective against both MRSA standard strains and clinical isolates. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and beneficial effects of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described in the following embodiments of the present invention are only exemplary descriptions of the specific embodiments of the present invention, and are intended to be used to explain the present invention, but do not constitute a limitation of the present invention.

[0024] The endpoints of ranges and any values ​​disclosed herein are not limited to the exact range or value, and these ranges or values ​​should be understood to include approximations to these ranges.

[0025] Example 1 Preparation of quaternized β-carboline compounds

[0026] Typical quaternized β-carboline compounds are prepared using the following reaction route:

[0027]

[0028] The specific steps are as follows:

[0029] (i) 30 mmol of tryptamine was dissolved in 25 mL of glacial acetic acid / methanol (10:1), and then 30 mmol of acetaldehyde aqueous solution was added. The reaction system was stirred at 80°C for 1 hour and then cooled to room temperature. The pH value was adjusted to 9-10 with ammonia water under ice bath stirring. After filtering and washing, the target compound 2 was obtained as a white solid with a yield of 97%.

[0030] (ii) 10 mmol of compound 2 and 186 mg of palladium on carbon (10%) were added to 50 mL of xylene, and then heated at 140° C. until compound 2 was completely converted. After filtration, concentration and silica gel column chromatography (petroleum ether / ethyl acetate system gradient elution), compound 3 was obtained as a white solid with a yield of 93%.

[0031] (iii) 1 mmol of compound 3 was dissolved in 5 mL of anhydrous N,N-dimethylformamide, and then 3 mmol of sodium hydride (60%) was added under ice bath, and 0.5 mmol of 1,9-dibromononane or 1,12-dibromododecane was added after stirring under ice bath for 30 min. After the reaction was completed by thin layer chromatography (TLC), the reaction was quenched with 1 mL of water, extracted with dichloromethane, dried over anhydrous sodium sulfate, and chromatographed on a silica gel column (gradient elution with petroleum ether / ethyl acetate system) to obtain a white solid, namely compound 4a (yield 84%) or 4b (yield 87%).

[0032] (iv) 1 mmol of compound 4a or 4b was dissolved in 15 mL of acetonitrile, and then 2.2 mmol of iodomethane was added. The mixture was heated and stirred at 70°C. After the reaction was completed by TLC, the temperature of the reaction solution was lowered to room temperature while stirring, and the target compound 5a or 5b was obtained by filtration.

[0033] Compound 5a: 9,9'-(1,9-nonane)bis(1,2-dimethyl-β-carboline-2-iodine salt), a light yellow solid, a melting point of 285-286°C, and a yield of 82%; 1 H NMR(CD3OD)δ:8.75(d,J=8.0Hz,2H),8.71(d,J=4.0Hz,2H),8.51(d,J=8.0Hz,2H),7.99(d,J=12.0Hz,2H),7.84(t,J=8.0H z,2H),7.48(t,J=8.0Hz,2H),4.72(t,J=8.0Hz,4H),4.41(s,6H),3.19(s,6H),1.77(t,J=8.0Hz,4H),1.39-1.21(m,10H); 13C NMR(CD3OD)δ:145.24,141.94,135.75,134.62,132.92,132.29,123.75,122. 33,119.25,115.69,112.08,46.39,45.56,30.72,29.33,29.11,26.46,16.96.

[0034] Compound 5b: 9,9'-(1,12-dodecane)bis(1,2-dimethyl-β-carboline-2-iodide), a light yellow solid, melting point 288-290°C, yield 78%; 1 H NMR(DMSO-d6)δ:8.75(d,J=8.0Hz,2H),8.71(d,J=4.0Hz,2H),8.51(d,J=8.0Hz,2H),7.99(d,J=8.0Hz,2H),7.85(t,J=8.0 Hz,2H),7.48(t,J=4.0Hz,2H),4.73(t,J=8.0Hz,4H),4.41(s,6H),3.19(s,6H),1.78(t,J=8.0Hz,4H),1.33-1.18(m,16H); 13 C NMR(DMSO-d6)δ:145.25,141.95,135.75,134.62,132.92,132.28,123.74,122.33 ,119.25,115.69,112.09,46.37,45.57,30.73,29.42,29.39,29.18,26.50,16.92.

[0035] Example 2 Antibacterial Activity Test of Quaternized β-Carboline Compounds

[0036] The minimum inhibitory concentration (MIC) of the test compounds was determined by the two-fold dilution method to evaluate the antibacterial activity of the compounds. Dimethyl sulfoxide (DMSO) was used to prepare 50 mmol of the test compound (5a, 5b) stock solution. The test strains selected were Staphylococcus aureus standard strain (ATCC 29213), MRSA standard strains (ATCC 43300 and ATCC33591, CGMCC1.12409) and MRSA clinical isolates (M-13, M-14, M-16, M-19, M-20). The compounds and bacterial suspension were diluted with Mueller-Hinton broth liquid culture medium. The final concentration of the compound in the 96-well plate was 0.125-128 μg / mL, and the final concentration of the bacterial suspension was 1×10 5CFU / mL, observe the bacterial growth after culturing at 37°C for 14 hours, and the value corresponding to the wells with no sterile growth and complete clarity under naked eye observation is the MIC value of the compound against bacteria. Vancomycin was used as a positive control, and phosphate buffer containing the corresponding DMSO concentration was used as a negative control.

[0037] The results of three parallel experiments were averaged, and the antibacterial activity is shown in Table 1. The antibacterial activity test results show that the quaternized β-carboline compounds of Example 1 have strong antibacterial activity, with MIC values ​​of 0.25 to 1 μg / mL, which is stronger than the clinical first-line drug vancomycin (1 to 2 μg / mL), and have the use of drugs for treating diseases related to MRSA infection.

[0038] Table 1. Antibacterial activity of the tested compounds

[0039]

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and do not constitute a limitation on the content of the present invention. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A quaternized β-carboline compound, characterized in that Its general structural formula is shown in Formula I, Wherein n is a positive integer from 9 to 12.

2. The method for preparing a quaternized β-carboline compound according to claim 1, characterized in that: Prepared by the following reaction route:

3. The preparation method according to claim 2, characterized in that: The preparation method comprises the following steps: (i) dissolving tryptamine in a glacial acetic acid / methanol solution, adding an acetaldehyde aqueous solution, and heating to react to obtain compound 2; (ii) Compound 2 is mixed with palladium on carbon and added into xylene, and heated to react to obtain Compound 3; (iii) dissolving compound 3 in anhydrous N,N-dimethylformamide, adding sodium hydride in an ice bath and stirring, and then adding dibromo long-chain alkyl to react to obtain compound 4; (iv) Compound 4 is dissolved in acetonitrile, iodomethane is added, and the mixture is heated and stirred to react to obtain Compound 5, which is the quaternized β-carboline compound.

4. Use of the quaternized β-carboline compound according to claim 1 for preparing an anti-MRSA drug.

5. An anti-MRSA pharmaceutical composition, characterized in that: The pharmaceutical composition comprises the quaternized β-carboline compound according to claim 1 and pharmaceutical excipients.

6. A pharmaceutical composition against MRSA as claimed in claim 5, characterized in that: The anti-MRSA pharmaceutical composition is used for treating infectious diseases caused by MRSA.

7. An anti-MRSA pharmaceutical composition according to claim 6, characterized in that: The infectious disease is bacteremia, pneumonia, myocarditis, wound infection or bone and joint infection.

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