Preparation of a methionine derivative and its salts and use thereof as an antibacterial agent

Abstract

The present invention relates to the technical field of chemical synthesis and applications, and particularly relates to methionine derivatives with the general formula (A) and their sulfonium salts. The preparation methods of such compounds are disclosed, as well as the inhibitory and bactericidal effects of the compounds on bacteria. The antibacterial and bactericidal properties of the compounds make them potentially useful in the research, development and application of antibacterial agents and antibacterial drugs. #imgabs0#

Description

Technical field

[0001] The present invention relates to the technical field of chemical synthesis and applications, and particularly relates to an organic synthesis and antibacterial use of a methionine derivative. Background art

[0002] While the living standards of humans are improving, the drug resistance of pathogenic bacteria such as bacteria, fungi, and molds is also increasing. The phenomenon of bacterial drug resistance poses a great threat to the physical and mental health of humans. The research and development of new antibacterial drugs have received extensive attention and emphasis. Pathogenic microorganisms are considered a major threat to human health, affecting multiple sectors such as food, animal husbandry, storage and packaging, and water pollution. Due to the increasing drug resistance of pathogenic bacteria, which is often caused by the long-term abuse or overuse of traditional antibacterial drugs, new methods and solutions are needed. Bacterial drug resistance has become a global public health crisis that urgently needs to be addressed. Among them, the research and development of new antibacterial drugs is the most effective means to treat various drug-resistant bacterial infections. Most researchers believe that cationic antibacterial agents can achieve antibacterial effects more effectively. The positively charged cationic groups adsorb negatively charged bacteria and aggregate on the cell wall, producing a chamber-blocking effect, resulting in the inhibition of bacterial growth and death; at the same time, by interacting with the substances and proteins in the microbial cell wall, the integrity of the microbial cell membrane is destroyed, the permeability of the membrane is changed, and then the internal structure and function of the cell are damaged, causing the lysis and death of the cell. For this reason, cationic antibacterial agents have been widely studied, such as quaternary ammonium salts, quaternary phosphonium salts, pyridinium salts, imidazolium salts, and alkylguanidine salts, etc. They have the advantages of rapid bactericidal action, stability and long efficacy. In recent years, sulfonium salt cationic antibacterial agents have received much attention in the research and development of antibacterial drugs. Sun Jing et al. reported a group of polyamino acid sulfonium polymers with selectivity and strong antibacterial ability (Adv Mater, 2021, 33, e2104402); Guan Dongliang et al. constructed sulfonium-modified vancomycin and explored the interaction of the compound with the bacterial cell membrane, providing a new strategy for combating drug-resistant bacterial infections and promoting the structural optimization and drug development of sulfonium derivatives (Angew Chem Int Ed Engl, 2019, 20, 6678). The research on sulfonium compounds as antibacterial agents has gradually expanded, and more functional sulfonium compounds will be gradually developed. Summary of the invention

[0003] The present invention uses methyl methionine hydrochloride as the main structure, forms sulfonium salt compounds by modifying the amino group with carbonamides of different lengths and linking different substituents to the sulfur atom; uses Gram-negative bacterium Escherichia coli and Gram-positive bacterium Staphylococcus aureus as test strains, and uses dodecyl dimethyl benzyl ammonium chloride (BAC), cetyl dimethyl benzyl ammonium chloride (16-BAC), and cetyl trimethyl ammonium chloride (CTAC) as controls to detect the minimum inhibitory concentration (MIC) and minimum bactericidal concentration of the sulfonium salt compounds against the strains; the MIC of the sulfonium compounds in the invention is stronger than that of the control substances BAC, 16-BAC, and CTAC, and the minimum bactericidal concentration (MBC) is better than or similar to that of the control substances BAC, 16-BAC, and CTAC.

[0004] The general formula A of the compounds of the present invention is as follows:

[0005]

[0006] In A, the amino acid chirality is in the L configuration and D configuration; n = 8, 10, 12, 14, 16; R = C2H5, C3H7, C4H9, CH2Ph, C3H6Ph.

[0007] The compounds of the above general formula may be:

[0008] S-butyl-N-decanoyl-D-methyl methionine chloride (A1),

[0009] S-butyl-N-dodecanoyl-D-methyl methionine chloride (A2),

[0010] S-butyl-N-tetradecanoyl-D-methyl methionine chloride (A3),

[0011] S-butyl-N-hexadecanoyl-D-methyl methionine chloride (A4),

[0012] S-butyl-N-octadecanoyl-D-methyl methionine chloride (A5),

[0013] S-(3-phenyl-propyl)-N-decanoyl-D-methyl methionine chloride (A6),

[0014] S-(3-phenyl-propyl)-N-dodecanoyl-D-methyl methionine chloride (A7),

[0015] S-(3-phenyl-propyl)-N-tetradecanoyl-D-methyl methionine chloride (A8),

[0016] S-(3-phenyl-propyl)-N-hexadecanoyl-D-methyl methionine chloride (A9),

[0017] Methyl S-(3-phenylpropyl)-N-octadecanoyl-D-methioninate chloride (A10).

[0018] The preparation methods of compounds A1 - A10 are shown in Scheme 1.

[0019] Scheme 1

[0020]

[0021] Synthesis method of compounds with general formula A: Under argon protection, dissolve methionine methyl ester hydrochloride (1 eq) and acyl chlorides with different chain lengths (1.5 eq) in DMF (5 mL) solution, add triethylamine (1.5 eq), slowly dropwise add acyl chloride at 0 °C and react for 30 min, stir at room temperature for 4 h, quench with water, extract with dichloromethane (20 mL × 2), retain the dichloromethane layer, dry successively with saturated brine (20 mL) and anhydrous sodium sulfate, evaporate the solvent under reduced pressure to obtain the crude product, separate by column chromatography on silica gel, elute with a mixed system of petroleum ether and ethyl acetate to obtain the intermediate product X for standby. Dissolve the intermediate product X (1 eq) and n-butyl iodide or 1-iodo-3-phenylpropane (1.5 eq) in dry acetonitrile (5 mL) solution, add silver tetrafluoroborate (1.2 eq), stir magnetically in an oil bath at 70 °C for 24 h, and then cool to room temperature. Filter to remove the precipitate, exchange with 50 mg of strongly basic chloride ion exchange resin for 2 h, evaporate the solvent under reduced pressure to obtain the crude product, separate by column chromatography on silica gel, elute with a mixed system of methanol and dichloromethane to obtain product A.

[0022] The antibacterial activity results of sulfonium salt cationic antibacterial agents show that A1, A2, A3, A4, A5, A6, A7, A8, A9, A10 have antibacterial activity against Staphylococcus aureus and Escherichia coli. The results of their MIC and MBC are shown in Table 1.

[0023] Table 1 MIC and MBC results of compounds A - A10 against Staphylococcus aureus and Escherichia coli

[0024] Description of the Drawings

[0025] Figure 1 It is the mass spectrum of compound A1 in Example 1 of the present invention;

[0026] Figure 2 It is the 1H NMR spectrum of compound A1 in Example 1 of the present invention;

[0027] Figure 3 It is the 13C NMR spectrum of compound A1 in Example 1 of the present invention;

[0028] Figure 4Mass spectrum of compound A6 in Example 6 of the present invention;

[0029] Figure 5 1H NMR spectrum of compound A6 in Example 6 of the present invention;

[0030] Figure 6 13C NMR spectrum of compound A6 in Example 6 of the present invention; Detailed implementation mode

[0031] The synthesis, structural characterization and antibacterial experiment of the methionine derivative antibacterial agent of the present invention will be described below through specific examples.

[0032] Example 1

[0033] S-butyl-N-decanoyl-D-methionine methyl chloride (A1),

[0034] Using the synthesis method of general formula A compound, reacting methionine methyl ester hydrochloride (0.7 g, 3.5 mmol) with decanoyl chloride, and reacting the obtained intermediate with n-iodoalkane to obtain product A1 (0.445 g, 1.2 mmol, yield 70%), which is a white solid particulate; R f = 0.28 (methanol-dichloromethane 1:20); 1 1H NMR (600 MHz, CDCl3) δ: 6.91 (dd, 1H, NH), 4.68 - 4.59 (m, 1H), 3.77 (d, 3H, OCH3), 3.58 - 3.22 (m, 5H, 2CH2NH), 2.92 (d, 3H, SCH3), 2.92 (d, 3H), 2.44 - 2.33 (m, 1H, NHCHCH2), 2.35 - 2.24 (m, 3H), 1.84 - 1.71 (m, 2H, SCH2CH2), 1.63 - 1.58 (m, 2H, CH2), 1.52 (dt, 2H, CH2), 1.37 - 1.15 (m, 14H, 7CH2), 1.00 (t, 3H, CH3), 0.87 (t, 3H, CH3); 13 13C NMR (600 MHz, CDCl3) δ: 174.72, 171.04, 52.91, 50.65, 41.65, 38.82, 35.97, 31.88, 29.38, 26.24, 25.90, 25.49, 22.67, 22.32, 21.56, 13.70; HR-MS (ESI) m / z: Calcd for C 20 H 40 NO3S + {[M-Cl-]+}: 374.2723, found: 374.2646; The mass spectrum of A1 is as attachedFigure 1 As shown, the 1H NMR spectrum is as attached Figure 2 As shown, the carbon spectrum is as attached Figure 3 as shown

[0035] Example 2

[0036] S-butyl-N-dodecanoyl-D-methionine methyl ester chloride (A2),

[0037] Using the synthesis method of the general formula A compound, methionine methyl ester hydrochloride (0.723 g, 3.62 mmol) was reacted with dodecanoyl chloride, and the resulting intermediate was reacted with n-iodoalkane to obtain product A2 (0.484 g, 1.2 mmol, yield 70%), which was a yellow oil; R f = 0.27 (methanol-dichloromethane 1:20); HR-MS (ESI) m / z: Calcd for C 22 H 44 NO3S + {[M-Cl-]+} 402.3134, found: 402.3036

[0038] Example 3

[0039] S-butyl-N-tetradecanoyl-D-methionine methyl ester chloride (A3),

[0040] Using the synthesis method of the general formula A compound, methionine methyl ester hydrochloride (0.60 g, 3.0 mmol) was reacted with tetradecanoyl chloride, and the resulting intermediate was reacted with n-iodoalkane to obtain product A3 (0.426 g, 0.9 mmol, yield 76%), which was a yellow oil; R f = 0.27 (methanol-dichloromethane 1:20); HR-MS (ESI) m / z: Calcd for C 24 H 48 NO3S + {[M-Cl - +} 430.3509, found: 430.3349

[0041] Example 4

[0042] S-butyl-N-hexadecanoyl-D-methionine methyl ester chloride (A4)

[0043] Using the synthesis method of the general formula A compound, methionine methyl ester hydrochloride (0.250 g, 1.25 mmol) was reacted with hexadecanoyl chloride, and the resulting intermediate was reacted with n-iodoalkane to obtain product A4 (0.200 g, 0.43 mmol, yield 87%), which was a yellow oil; R f ​= 0.27 (methanol-dichloromethane 1:20); HR-MS (ESI) m / z: Calcd for C 26 H 52 NO3S + {[M-Cl - +} 458.3758, found: 458.3662.

[0044] Example 5

[0045] S-butyl-N-octadecanoyl-D-methionine methyl ester chloride (A5)

[0046] Using the synthetic method of the general formula A compound, methionine methyl ester hydrochloride (0.30 g, 1.5 mmol) was reacted with octadecanoyl chloride, and the resulting intermediate was reacted with n-iodoalkane to obtain product A5 (0.220 g, 0.45 mmol, yield 79%), which was a yellow oil; R f = 0.27 (methanol-dichloromethane 1:20); HR-MS (ESI) m / z: Calcd for C 28 H 56 NO3S + {[M-Cl - +} 486.4070, found: 486.3975.

[0047] Example 6

[0048] S-(3-phenyl-propyl)-N-decanoyl-D-methionine methyl ester chloride (A6)

[0049] Using the synthetic method of the general formula A compound, methionine methyl ester hydrochloride (0.830 g, 4.16 mmol) was reacted with decanoyl chloride, and the resulting intermediate was reacted with 1-iodo-3-phenylpropane to obtain product A6 (0.700 g, 2.8 mmol, yield 89%), which was a yellow oil; Rf = 0.27 (methanol-dichloromethane 1:20); 1H NMR (600 MHz, CDCl3) δ: 7.30 - 7.16 (m, 5H, C6H5), 6.98 (d, 1H, NH), 4.59 (m, 1H), 3.73 (d, 3H, OCH3), 3.57 - 3.12 (m, 2H, SCH2), 2.86 (d, 3H, SCH3), 2.81 (d, 2H), 2.38 - 2.16 (m, 1H, NHCHCH2), 2.16 - 2.05 (m, 1H), 1.59 (ddd, 1H), 1.46 - 1.06 (m, 11H), 0.87 (d, 3H, CH3); 13 ​​13C NMR (600 MHz, CDCl3) δ: 174.74, 171.00, 139.07, 129.61 - 127.93, 126.86, 52.93, 50.60, 41.29, 38.97, 35.98, 33.99, 31.89, 30.48 - 28.39, 27.30 - 24.49, 23.46 - 20.68, 14.12; HR-MS (ESI) m / z: Calcd for C 25 H 42 NO3S + {[M-Cl-]+}: 436.2880, found: 436.3070; The mass spectrum of A6 is as attached Figure 4 as shown, and the 1H NMR spectrum is as attached Figure 5 as shown, and the 13C NMR spectrum is as attached Figure 6 as shown.

[0050] Example 7

[0051] S-(3-Phenyl-propyl)-N-dodecanoyl-D-methionine methyl chloride (A7)

[0052] Using the synthetic method of the general formula A compound, methionine methyl ester hydrochloride (0.687 g, 3.44 mmol) was reacted with dodecanoyl chloride, and the resulting intermediate was reacted with 1-iodo-3-phenylpropane to obtain product A7 (0.600 g, 2.4 mmol, yield 92%), which is a yellow oil; R f = 0.27 (methanol - dichloromethane 1:20); HR-MS (ESI) m / z: Calcd for C 27 H 46 NO3S + {[M-Cl - +} 464.3263, found: 464.3193.

[0053] Example 8

[0054] S-(3-Phenyl-propyl)-N-tetradecanoyl-D-methionine methyl chloride (A8)

[0055] Using the synthetic method of the general formula A compound, methionine methyl ester hydrochloride (0.465 g, 2.33 mmol) was reacted with tetradecanoyl chloride, and the resulting intermediate was reacted with 1-iodo-3-phenylpropane to obtain product A8 (0.398 g, 1.6 mmol, yield 90%), which is a yellow oil; R f = 0.27 (methanol - dichloromethane 1:20); HR-MS (ESI) m / z: Calcd.for C 29 H​50 NO3S + {[M-Cl - +}492.3614, found: 492.3506.

[0056] Example 9

[0057] S-(3-Phenyl-propyl)-N-hexadecanoyl-D-methionine methyl chloride (A9)

[0058] Using the synthetic method of the general formula A compound, methionine methyl ester hydrochloride (0.880 g, 4.41 mmol) was reacted with hexadecanoyl chloride, and the resulting intermediate was reacted with 1-iodo-3-phenylpropane to obtain product A9 (0.652 g, 1.25 mmol, yield 78%), which was a yellow oil; R f f = 0.27 (methanol-dichloromethane 1:20); HR-MS (ESI) m / z: Calcd forC 31 H 54 NO3S + {[M-Cl - +}520.3906, found: 520.3819.

[0059] Example 10

[0060] S-(3-Phenyl-propyl)-N-octadecanoyl-D-methionine methyl chloride (A10)

[0061] Using the synthetic method of the general formula A compound, methionine methyl ester hydrochloride (0.808 g, 4.05 mmol) was reacted with octadecanoyl chloride, and the resulting intermediate was reacted with 1-iodo-3-phenylpropane to obtain product A10 (0.530 g, 1.0 mmol, yield 69%), which was a yellow oil; Rf = 0.27 (methanol-dichloromethane 1:20); HR-MS (ESI) m / z: Calcd.forC 33 H 58 NO3S + {[M-Cl - +}548.4276, found: 548.4132.

[0062] Minimum inhibitory concentration MIC test

[0063] Compounds A1 - A10, BAC, 16 - BAC, and CTAC were dissolved in DMSO to prepare compound solutions. The bacteria were cultured to the logarithmic growth phase, and OD 600 was measured to be 0.1, and the bacterial suspension was diluted to a concentration of 1×10​​​7 CFU.mL -1 , Add 200 μL of the bacterial suspension to each well of a 96-well plate, and add 1 μL of A1 - A10, BAC, 16 - BAC, and CTAC to the 96-well plate respectively, so that the final concentration of the compound is 25 μmol·L -1 , 12.5 μmol·L -1 , 6.25 μmol·L -1 , 3.125 μmol·L -1 , 1.5625 μmol·L -1 , 0.781215 μmol·L -1 , 0.3906 μmol·L -1 . Additionally, set up wells containing only the culture medium and wells containing only the bacterial solution (1 μL of DMSO is added to the wells) as controls, with 3 parallel sub-wells, and place them in an incubator at 37 °C for 24 h. Place the 96-well plate in a microplate reader, measure the absorbance at a wavelength of 600 nm, and calculate the MIC of each compound.

[0064] Example 5

[0065] Minimum bactericidal concentration MBC test

[0066] Cultivate the bacteria until the logarithmic growth phase, measure OD 600 = 0.1, dilute the bacterial suspension to a concentration of 1×10 7 CFU·mL -1 , Add 200 μL of the bacterial suspension to each well of a 96-well plate, and add 1 μL of A1 - A10, BAC, 16 - BAC, and CTAC to the 96-well plate respectively, so that the final concentration of the compound is greater than or equal to the MIC value, and treat for 24 h. Sequentially aspirate 50 μL of the mixture and drop it onto an LB agar plate, incubate at 37 °C for 24 h, observe the colony state, and take the compound concentration with less than 5 single colonies counted on the agar plate as the minimum bactericidal concentration.

Claims

1. Compounds of general formula (A): wherein the amino acid chirality is in the L-configuration or D-configuration; n = 8, 10, 12, 14, 16; R = C2H5, C3H7, C4H9, CH2Ph, C3H6Ph.

2. A compound of the general formula (A) according to claim 1, characterized in that They are derivatives of methionine.

3. A compound of the general formula (A) according to claim 1, characterized in that They contain a sulfonium cation group.

4. A compound of general formula (A) according to claim 1, characterized in that They contain a straight-chain alkyl group with 9, 11, 13, 15, or 17 carbons.

5. The compound of general formula (A) according to claim 1, wherein it is any of the following compounds: S-butyl-N-decanoyl-D-methionine methyl ester chloride (A1), S-butyl-N-dodecanoyl-D-methionine methyl ester chloride (A2), S-butyl-N-tetradecanoyl-D-methionine methyl ester chloride (A3), S-butyl-N-hexadecanoyl-D-methionine methyl ester chloride (A4), S-butyl-N-octadecanoyl-D-methionine methyl ester chloride (A5), S-(3-phenyl-propyl)-N-decanoyl-D-methionine methyl ester chloride (A6), S-(3-phenyl-propyl)-N-dodecanoyl-D-methionine methyl ester chloride (A7), S-(3-phenyl-propyl)-N-tetradecanoyl-D-methionine methyl ester chloride (A8), S-(3-phenyl-propyl)-N-hexadecanoyl-D-methionine methyl ester chloride (A9), S-(3-phenyl-propyl)-N-octadecanoyl-D-methionine methyl ester chloride (A10).

6. A pharmaceutical composition containing the compound of general formula (A) according to claim 1.

7. Use of the compound of general formula (A) according to claim 1 for antibacterial and bactericidal purposes.

8. For the use according to claim 7, the compound of general formula (A) has antibacterial and bactericidal effects on the Gram-negative bacterium Escherichia coli and the Gram-positive bacterium Staphylococcus aureus.

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