RU2785140C1 - APPLICATION OF 1-{1-METHYLPYRROLO[1,2-a]QINOXALINE-5(4H)-YL}ETHAN-1-ONE AS ANTIBACTERIAL AGENT AGAINST GRAM-POSITIVE MICROORGANISMS - Google Patents

Abstract

FIELD: antibacterial agents.

SUBSTANCE: invention relates to the use of 1-{1-methylpyrrolo[1,2-a]quinoxalin-5(4H)-yl}ethan-1-one of formula 1 as an antibacterial agent against Gram-positive microorganisms.

EFFECT: antibacterial effect against gram-positive microorganisms.

1 cl, 1 tbl, 3 ex

Description

The invention relates to the field of organic chemistry - new biologically active compounds - substituted pyrrolo[1,2- a ]quinoxaline, namely 1-{1-methylpyrrolo[1,2- a ]quinoxalin-5(4H)-yl}ethan- 1-onu 1 formulas:

compound 1 has antibacterial activity, which suggests its use in medicine as a potential drug with antibacterial properties.

The structural analogue of the claimed compound is 4-{[(2,6-dimethylphenyl)amino]acetyl}-3,4-dihydroquinoxalin-2(1H)-one2 having antibacterial activity [Arch. Pharm. Res. 2011, 34, 1605-1614; doi: 10.1007/s12272-011-1004-4] formulas:

The comparison standard was phenyl salicylate 3 of the formula:

which is widely used in medical practice, and is analogous in action [Mashkovsky M.D. Medicines. - 16th ed., revised, corrected. and additional - M.: New wave, 2012. - p. 950].

The objective of the invention is to search for substances with a pronounced antibacterial effect in the series of substituted pyrrolo[1,2- a ]quinoxalines.

The task is achieved by obtaining 1-{1-methylpyrrolo[1,2- a ]quinoxalin-5(4H)-yl}ethan-1-one, which has antibacterial activity.

The claimed compound 1 is synthesized by a three-stage method, which includes the acylation of N-[(5-methylfuran-2-yl)methyl]-2-nitroaniline 4, the processing of N-(5-methylfuran-2-yl)methyl]-N-(2- nitrophenyl)acetamide 5 with a mixture of glacial acetic and concentrated hydrochloric acids at room temperature and treatment of the resulting N-(2,5-dioxohexyl)-N-(2-nitrophenyl)acetamide 6 with carbonyl iron powder in glacial acetic acid at boiling, followed by isolation of the target product by known methods according to the scheme:

Example 1. Preparation of compound 1. Step 1. To a solution of 1.16 g (5 mmol) N-[(5-methylfuran-2-yl)methyl]-2-nitroaniline 4 and 1.39 ml (10 mmol) triethylamine (TEA) in dry acetonitrile (10 ml), 0.71 ml (10 mmol) of acetyl chloride are added dropwise. The reaction mixture was refluxed for 2 h. Then the reaction mixture was poured into an aqueous solution of NaOH (0.1 M, 100 ml). The product is extracted with ethyl acetate (3×30 ml). The combined organic fractions are washed with saturated NaCl solution (3×20 ml), dried over anhydrous Na ₂ SO ₄ . The solvent is evaporated to dryness under reduced pressure. The residue was purified by column chromatography on silica gel using petroleum ether/ethyl acetate (20:1 to 10:1 gradient) as eluent, the purified product 5 was recrystallized from petroleum ether/ethyl acetate. Yield 83%. T _pl =85-86°C. Stage 2. To a solution of 0.822 g (3 mmol) of N-[(5-methylfuran-2-yl)methyl]-N-(2-nitrophenyl)acetamide 5 in 16 ml of glacial acetic acid is added concentrated hydrochloric acid (12 M, 3.2 ml). The reaction mixture was stirred at room temperature for 22 hours Then the reaction mixture was poured into H ₂ O (50 ml) and neutralized to pH~7 with NaHCO ₃ . The product is extracted with ethyl acetate (3×30 ml). The combined organic fractions are washed with saturated NaCl solution (3×20 ml), dried over anhydrous Na ₂ SO ₄ . The solvent is evaporated to dryness under reduced pressure. The residue was purified by silica gel column chromatography using petroleum ether/ethyl acetate (20:1 to 4:1 gradient) as eluent, the purified product 6 was recrystallized from petroleum ether/ethyl acetate. Yield 81%. T _pl =101-102°C. Stage 3. To a solution of 0.438 g (1.5 mmol) of N-(2,5-dioxohexyl)-N-(2-nitrophenyl)acetamide 6 in glacial acetic acid (6 ml) was added 1.26 g (22.5 mmol) of carbonyl iron. The reaction mixture is refluxed for 3 minutes. Then the reaction mixture was poured into H ₂ O (100 ml) and neutralized to pH~7 with NaHCO ₃ . Unreacted iron is filtered off and washed with hot ethyl acetate (3×5 ml). The aqueous layer is extracted with ethyl acetate (3×40 ml). The combined organic fractions are washed with saturated NaCl solution (3×20 ml), dried over anhydrous Na ₂ SO ₄ . The solvent is evaporated to dryness under reduced pressure. The residue was purified by silica gel column chromatography using petroleum ether/ethyl acetate (gradient 20:1 to 15:1) as eluent. Product 1 is recrystallized from petroleum ether/ethyl acetate. Yield 36%. T _pl =143 - 144°C. Found, %: C 74.32, H 6.27, N 12.37. C ₁₄ H ₁₄ N ₂ O. Calculated, %: C 74.31, H 6.24, N 12.33. IR spectrum, (CaF ₂ ), ν _max , cm ^-1 : 1646, 1523, 1493, 1404, 1323, 1250, 1133, 1124, 1031. ¹ H NMR spectrum, (400 MHz, DMSO-d ₆ ), δ, ppm: 7.69-7.67 (m, 1H), 7.60-7.53 (m, 1H), 7.37-7.33 (m, 1H), 7.26-7.22 (m, 1H), 5.93 (s, 2H), 4.71 ( s, 2H), 2.52 (s, 3H), 2.16 (s, 3H). ^13C NMR spectrum (100 MHz, DMSO- _d6 ), δ, ppm: 167.5, 130.9, 130.7, 127.1, 126.0, 125.9, 125.5, 123.6, 113.0, 109.4, 103.2, 40.6, 21.3, 14.3. HRMS (ESI ⁺ ) m/z: [M+H] ⁺ calculated for C ₁₄ H ₁₅ N ₂ O ⁺ 227.1179, found 227.1183. The resulting compound 1 is a white crystalline substance, soluble in chloroform, toluene, acetone, ethyl acetate, ethanol.

Example 2. To characterize the antibacterial activity, standard parameters were used: the minimum inhibitory concentration (MIC), which was determined by the modified method of two-fold serial dilutions (MUK 4.2.1390-04 Determination of the sensitivity of microorganisms to antibacterial drugs) and the minimum bactericidal concentration (MBC) [Medical laboratory technologies : Guidelines for clinical laboratory diagnostics, p / r Kaprischenko, 2013, Vol. 2, p. 407]. Tests were performed using cultures of model microorganisms Escherichia coli MC4100 and Staphylococcus epidermidis ATCC29887 on Luria-Bertani nutrient medium in 96-well polystyrene plates. The final concentration of microorganisms in the wells was 5*10 ⁵ CFU/ml. Cultivation was carried out at 37°C without stirring. Determination of the MIC and seeding for the determination of MBC was carried out after 24 hours. At the first stage, the test compound was dissolved in dimethyl sulfoxide (DMSO), further dilutions were made in methanol. As the initial concentrations in the tests, we used concentrations that, when added to the Luria-Bertani nutrient medium, did not form a precipitate (from 0.2 to 4 mg/mL).

Example 3. Acute toxicity (LD ₅₀ , mg/ml) of compound 1 was determined by the method of G.N. Pershin [Pershin G.N. Methods of experimental chemotherapy // M., S. 100, 1971, 109-117]. Compound 1 was administered intraperitoneally to white mice weighing 16-18 g as a suspension in 2% starch mucus, and the behavior and death of the animals were observed for 10 days. For test compound 1, the LD ₅₀ is >500 mg/kg.

According to the classification of drug toxicity, compound 1 belongs to the IV class of low-toxic drugs [Izmerov N.F., Sanotsky I.V., Sidorov K.K. Parameters of toxicometry of industrial poisons at a single exposure: a Handbook. M., 1977, p. 196]. The test results are presented in the table:

As can be seen from the table, the claimed compound 1 exceeds the reference drug (Phenyl salicylate) in antibacterial activity by 5 times in relation to St. epidermidis. Thus, 1-{1-methylpyrrolo[1,2- a ]quinoxalin-5(4H)-yl}ethan-1-one 1 exhibits higher activity compared to the reference standard against gram-positive microorganisms, which makes it possible to use it to create new drugs, purposeful action.

Claims (3)

Application of 1-{1-methylpyrrolo[1,2- a ]quinoxalin-5(4 H )-yl}ethan-1-one:

as an antibacterial agent against gram-positive microorganisms.