Florfenicol derivatives, preparation methods and applications in antibacterial drugs

Abstract

The present invention provides a florfenicol derivative, a preparation method thereof, and an application in antibacterial infection drugs, belonging to the field of florfenicol derivatives. The preparation method of the florfenicol derivative includes an esterification step and a condensation acylation step. The florfenicol derivative has a significantly enhanced antibacterial effect compared with florfenicol; its water solubility is significantly improved compared with florfenicol, and it is easy to be prepared into various dosage forms; after the florfenicol derivative enters an animal body, it can be effectively converted into florfenicol, is easy to absorb, and has a long duration of antibacterial concentration.

Description

Technical Field

[0001] The present invention relates to the field of florfenicol derivatives, and in particular to florfenicol derivatives, preparation methods and applications in antibacterial drugs. Background Art

[0002] Florfenicol, with the chemical name of 2,2-dichloro-N-[(1R,2S)-3-fluoro-1-hydroxy-1-(4-methylsulfonylphenyl)-2-propyl]acetamide, has the molecular formula of C 12 H 14 Cl2FNO4S. Florfenicol is a monofluoro derivative of synthetic thiamphenicol, presenting as a white or off-white crystalline powder. It is a broad-spectrum antibacterial drug for animals only, and was first marketed in Japan in 1990. In 1993, Norway approved this drug for treating furunculosis of salmon. In 1995, France, the UK, Austria, Mexico and Spain approved its use for treating bacterial diseases of the bovine respiratory system.

[0003] As an antibiotic for animals only, florfenicol has a broad antibacterial spectrum and is widely used in veterinary clinical practice to prevent and treat bacterial infectious diseases of animals such as fish, chickens, pigs and cattle. However, due to the overuse of antibacterial drugs, a series of problems such as the generation of a large amount of drug resistance and the reduction of antibiotic efficacy have occurred, posing a serious threat to the health of humans and animals. Therefore, how to avoid the generation of drug resistance while ensuring the antibacterial ability of florfenicol products is a major technical problem in the veterinary drug field. At the same time, the water solubility of florfenicol is not good, which is inconvenient for clinical use. Developing florfenicol products with excellent water solubility has always been a research hotspot in the veterinary drug field.

[0004] Furthermore, the applicant has found through research that after existing florfenicol products enter the animal body, the absorption rate is not ideal, the time for florfenicol in the animal's blood to reach the ideal concentration is relatively long, the onset of drug effect is slow, and the maintenance time of the antibacterial concentration is short.

[0005] Therefore, developing a florfenicol derivative that can avoid the generation of drug resistance while ensuring the antibacterial ability of florfenicol products; at the same time, improving the water solubility of florfenicol products, improving the absorption rate of animals to it, shortening the time for florfenicol in the animal's blood to reach the ideal concentration, increasing the onset speed of drug effect, and prolonging the maintenance time of the antibacterial concentration of florfenicol is of great significance. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides florfenicol derivatives, preparation methods and applications in antibacterial drugs to achieve the following invention purposes:

[0007] (1) While ensuring the antibacterial ability of florfenicol, avoiding the generation of drug resistance;

[0008] (2) Improve the water solubility of florfenicol products;

[0009] (3) Improve the absorption rate of animals to it, shorten the time for florfenicol in animal blood to reach the ideal concentration, thereby enhancing the onset speed of the drug effect, and prolong the maintenance time of the antibacterial concentration of florfenicol.

[0010] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0011] A florfenicol derivative, having the following structural formula:

[0012] (I)

[0013] Wherein, n is an integer ≥ 0, a is an integer ≥ 1, b is an integer ≥ 0, and c is an integer ≥ 0.

[0014] Preferably, the structural formula of the florfenicol derivative is one of the following: n = 1, a = 2, b = c = 0; n = 1, a = 3, b = c = 0; n = 1, a = 3, b = c = 1.

[0015] A method for preparing a florfenicol derivative, comprising: an esterification step and a condensation acylation step;

[0016] The method of the esterification step is that florfenicol is contacted with an acid anhydride and subjected to an esterification reaction to obtain compound II;

[0017] The method of the condensation acylation step is that the compound II is contacted with a primary amine compound III and subjected to a condensation acylation reaction to obtain compound I, that is, a florfenicol derivative;

[0018] The compound I has the following structural formula:

[0019] (I)

[0020] Wherein, n is an integer ≥ 0, a is an integer ≥ 1, b is an integer ≥ 0, and c is an integer ≥ 0;

[0021] The compound II has the following structural formula:

[0022] (Ⅱ)

[0023] Wherein, n is an integer ≥ 0;

[0024] Preferably, n = 1 in the compound II.

[0025] The primary amine compound III has the following structural formula:

[0026] (III)

[0027] Among them, a is an integer ≥ 1, b is an integer ≥ 0, and c is an integer ≥ 0

[0028] Preferably, the primary amine compound III is one of the following: a = 2, b = c = 0; a = 3, b = c = 0; a = 3, b = c = 1.

[0029] Furthermore, the method of the esterification step is to dissolve a predetermined amount of florfenicol and an acid anhydride in a solvent, add a first catalyst, and under certain temperature conditions, after the esterification reaction for a period of time, concentrate under reduced pressure and crystallize to obtain compound II;

[0030] In the esterification step, the molar ratio of florfenicol to the acid anhydride is 1:1 - 1.5, the reaction temperature is 40 - 90 °C, and the reaction time is 2 - 6 h;

[0031] Preferably, in the esterification step, the reaction temperature is 50 - 75 °C and the reaction time is 3 - 5 h.

[0032] In the esterification step, the first catalyst is 4 - dimethylaminopyridine, and the weight ratio of the first catalyst to florfenicol is 0.01 - 0.1:1; preferably 0.02 - 0.06:1.

[0033] The method of condensation acylation is to dissolve a predetermined amount of compound II and compound III in a solvent, add a second catalyst, and under certain temperature conditions, stir and react for a certain time to obtain a reaction solution; extract the reaction solution with an extraction solvent to obtain an organic phase; then wash the organic phase with a saturated sodium chloride solution, separate the organic phase, and the organic phase is dried, concentrated, and crystallized to obtain compound I;

[0034] In the condensation acylation step, the molar ratio of compound II to compound III is 1:1 - 1.5, the reaction temperature is 0 - 35 °C, and the stirring reaction time is 4 - 8 h;

[0035] Preferably, in the condensation acylation step, the reaction temperature is 5 - 30 °C.

[0036] In the condensation esterification step, the second catalyst is at least one of the following: 1 - hydroxybenzotriazole, 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride, triethylamine; the molar ratio of the second catalyst to compound II is 0.5 - 1.5:1;

[0037] In the condensation acylation step, the extraction solvent is at least one of the following: ethyl acetate, toluene, methyl tert - butyl ether, petroleum ether, n - hexane, dichloromethane.

[0038] Further, in the esterification step and the condensation acylation step, the solvent is one of the following: dichloromethane, toluene, ethyl acetate, acetone, cyclohexanone, tetrahydrofuran, N,N-dimethylformamide.

[0039] Preferably, in the esterification step, the solvent is one of the following: acetone, toluene, tetrahydrofuran.

[0040] Preferably, in the condensation acylation step, the solvent is N,N-dimethylformamide.

[0041] Further, in the esterification step and the condensation acylation step, the crystallization solvent used for crystallization is at least one of the following: methanol, ethanol, isopropanol, acetone, water.

[0042] Use of the florfenicol derivative in antibacterial infection drugs.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] (1) The florfenicol derivative of the present invention has a long half-life of absorption in animals, and the antibacterial effect is significantly enhanced compared with florfenicol.

[0045] (2) The florfenicol derivative of the present invention has significantly improved water solubility compared with florfenicol and is easy to be prepared into various dosage forms.

[0046] (3) The florfenicol derivative of the present invention is obtained by modifying the structure of florfenicol. After the drug molecule enters the animal body, the florfenicol derivative can be well converted into florfenicol and is easy to absorb; 2 hours after intravenous injection, the concentration of florfenicol in the animal blood can exceed 18 μg / mL, the drug effect takes effect quickly, and the drug effect time is long; moreover, within the time period of 0.5 - 22 hours after the drug molecule enters the animal body, the blood drug concentration of florfenicol can be maintained higher than the minimum inhibitory concentration (i.e., MIC 3 μg / mL).

[0047] (4) Compared with florfenicol, the florfenicol derivative of the present invention has a higher peak blood drug concentration of the converted florfenicol in the body and can maintain the blood drug concentration of florfenicol higher than the minimum inhibitory concentration (MIC value greater than 3 μg / mL) for a longer time (more than 20 hours).

[0048] (5) The preparation method of the florfenicol derivative of the present invention has easily available raw materials, mild reaction conditions, and simple process, and can meet the requirements of large-scale industrial production. Description of the Drawings

[0049] Figure 1 It is the reaction formula for preparing the florfenicol derivative of the present invention;

[0050] In the figure: Compound I is a florfenicol derivative; Compound IV is florfenicol.

[0051] Figure 2 It is the 1H NMR spectrum of Compound I-1 in Example 1.

[0052] Figure 3 It is the 13C NMR spectrum of Compound I-1 in Example 1.

[0053] Figure 4 It is the 1H NMR spectrum of Compound I-2 in Example 2.

[0054] Figure 5 It is the 13C NMR spectrum of Compound I-2 in Example 2.

[0055] Figure 6 It is the 1H NMR spectrum of Compound I-3 in Example 3.

[0056] Figure 7 It is the 13C NMR spectrum of Compound I-3 in Example 3.

[0057] Figure 8 It is the curve graph showing the changes in the concentrations of the florfenicol derivative and florfenicol in the plasma of the test pigs over time after administering Compound I-1 of Example 1 at a predetermined dose in Application Test Example 1.

[0058] Figure 9 It is the curve graph showing the changes in the concentrations of the florfenicol derivative and florfenicol in the plasma of the test pigs over time after administering Compound I-2 of Example 2 at a predetermined dose in Application Test Example 1.

[0059] Figure 10 It is the curve graph showing the changes in the concentrations of the florfenicol derivative and florfenicol in the plasma of the test pigs over time after administering Compound I-3 of Example 3 at a predetermined dose in Application Test Example 1.

[0060] Figure 11 It is the curve graph showing the changes in the concentration of florfenicol in the plasma of each test pig over time after administering the florfenicol reference substance and Compound I-1, Compound I-2, and Compound I-3 at a predetermined dose in Application Test Example 1. Detailed implementation manners

[0061] For a clearer understanding of the technical features, objectives, and effects of the present invention, the technical solutions in the embodiments of the present invention will now be representatively described in combination with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0062] Example 1

[0063] This example provides a florfenicol derivative, which is prepared by the following preparation method:

[0064] 1. Esterification step

[0065] 50 g of florfenicol and 14 g of succinic anhydride are added to 300 mL of acetone, stirred and dissolved, 1 g of 4-dimethylaminopyridine is added, heated to 50 °C, and stirred and reacted for 5 h; at a temperature of 45 °C and a vacuum of 0.07 MPa, it is concentrated under reduced pressure until the mass does not change to obtain a concentrate; the concentrate is added to a 50% ethanol aqueous solution, heated to 65 °C, stirred and dissolved, cooled to 10 °C, and stirred and crystallized at 50 rpm for 8 h, the solid is filtered out, and vacuum dried at 50 °C for 8 hours to obtain 58.5 g of a white solid (i.e., compound II-1).

[0066] In the said compound II-1, n = 1.

[0067] 2. Condensation acylation step

[0068] 46 g of compound II-1 and 9 g of compound III-1 (2-dimethylaminoethylamine) are dissolved in 300 mL of N,N-dimethylformamide, 15 g of 1-hydroxybenzotriazole, 10.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 10 g of triethylamine are added, and stirred at 100 rpm for 8 h at a temperature of 5 °C. After the reaction is completed, 300 mL of purified water is added; the reaction solution is extracted 3 times with 150 mL of dichloromethane each time, and the organic phases are combined; then the organic phase is washed once with 100 mL of saturated sodium chloride solution, the organic phase is separated, and the organic phase is dried over anhydrous sodium sulfate until the water content is between 1-2 wt%, and concentrated until the mass does not change; then it is added to a 50% acetone solution, heated to 55 °C and stirred to dissolve, cooled to 5 °C, and stirred and crystallized at 50 rpm for 8 h, the solid is filtered out, and vacuum dried at 50 °C for 8 hours to obtain 49.8 g of a white solid compound I-1.

[0069] In the structure of the said compound I-1, n = 1, a = 2, b = c = 0. The specific structural formula is as follows:

[0070] .

[0071] The nuclear magnetic resonance hydrogen spectrum and carbon spectrum detection results of the said compound I-1 are as follows:

[0072] 11H NMR (600 Hz, CDCl3) δ 7.96 (s, 1H), 7.85 - 7.86 (d, J = 6 Hz, 2H), 7.59 - 7.60 (d, J = 6 Hz, 2H), 7.28 (t, J = 6 Hz, 1H), 5.89 (s, 1H), 5.17 (d, J = 6 Hz, 1H), 4.68 - 4.47 (m, 2H), 4.34 (m, 1H), 3.63 (t, J = 6 Hz, 2H), 3.06 (s, 3H), 2.96 (t, 2H), 2.71 - 2.73 (t, J = 12 Hz, 2H), 2.49 - 2.51 (t, J = 6 Hz, 2H), 2.23 (s, 6H).

[0073] 13 13C NMR (600 Hz, CDCl3) δ 177.4 (1C), 164.5(1C), 162.6(1C), 147.4 (1C), 139.9 (1C), 127.5 (2C), 127.1 (2C), 81.9 (1C), 70.1 (1C), 66.2 (1C), 56.2 (1C), 55.1 (1C), 45.4 (2C), 44.5 (1C), 36.6 (1C), 31.5 (1C), 29.7 (1C).

[0074] This example also provides a florfenicol derivative, namely the aforementioned compound I-1.

[0075] Example 2

[0076] A florfenicol derivative is prepared by the following preparation method:

[0077] 1. Esterification step

[0078] Dissolve 50 g of florfenicol and 18 g of succinic anhydride in 300 mL of tetrahydrofuran. With stirring, add 2 g of 4-dimethylaminopyridine, heat to 66 °C, and keep the temperature for reflux reaction for 4 h; under the conditions of a temperature of 50 °C and a vacuum degree of 0.075, concentrate under reduced pressure until the mass does not change to obtain a concentrate; add the concentrate to a 50% methanol aqueous solution, heat to 60 °C, stir to dissolve, cool to 5 °C, stir and crystallize at 80 rpm for 6 h, filter out the solid, and dry in vacuum at 50 °C for 8 hours to obtain 59.6 g of a white solid (i.e., compound II-1).

[0079] In the said compound II-1, n = 1.

[0080] 2. Condensation acylation step

[0081] Dissolve 46 g of Compound II-1 and 10.2 g of Compound III-2 (3-dimethylaminopropylamine) in 300 mL of N,N-dimethylformamide. Add 13.5 g of 1-hydroxybenzotriazole, 11.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 12.5 g of triethylamine. Stir at 150 rpm for 6 h at 20 °C. After the reaction is complete, add 300 mL of purified water, and extract the reaction solution with ethyl acetate three times, 150 mL each time. Combine the organic phases. Then wash the organic phase once with 80 mL of saturated sodium chloride solution, separate the organic phase, dry the organic phase over anhydrous sodium sulfate until the water content is between 1 - 2 wt%, and concentrate until the mass remains unchanged. Then add it to a 50% aqueous isopropyl alcohol solution, heat to 65 °C, stir to dissolve, cool to 0 °C, stir and crystallize at 80 rpm for 6 h, filter out the solid, and dry it under vacuum at 50 °C for 8 h to obtain 51.5 g of an off-white solid, which is Compound I-2.

[0082] In the structure of the said Compound I-2, n = 1, a = 3, b = c = 0. The specific structural formula is as follows:

[0083] 。

[0084] The detection results of the nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the said Compound I-2 are as follows:

[0085] 1 H NMR (600 Hz, CDCl3) δ7.98 (s, 1H), 7.87 - 7.88 (d, J = 6 Hz, 2H), 7.61 - 7.63 (d, J = 12 Hz, 2H), 7.45 - 7.47 (d, J = 12 Hz, 1H), 5.93 (s, 1H), 5.16 (d, J = 6 Hz, 1H), 4.45 - 4.68 (m, 2H), 4.35(m, 1H), 3.52 - 3.55 (t, J = 6 Hz, 12 Hz, 2H), 3.04 (s, 3H), 2.94 - 2.98 (t, J = 12 Hz, 2H), 2.70 - 2.72 (t, J = 6 Hz, 2H), 2.28 - 2.30 (t, J = 6 Hz, 2H), 2.18 (s, 6H), 1.71 - 1.74 (m, 2H).

[0086] 1313C NMR (600 Hz, CDCl3) δ 177.3 (1C), 164.5 (1C), 162.6 (1C), 147.8 (1C), 139.7 (1C), 127.4 (2C), 127.1 (2C), 81.7 (1C), 69.8 (1C), 66.2 (1C), 57.0 (1C), 55.2 (1C), 45.3 (2C), 44.5 (1C), 37.1 (1C), 31.4 (1C), 28.5 (1C), 25.6 (1C).

[0087] This example also provides a florfenicol derivative, namely the aforementioned compound I-2.

[0088] Example 3

[0089] A florfenicol derivative is prepared by the following preparation method:

[0090] 1. Esterification step

[0091] Dissolve 50 g of florfenicol and 16 g of succinic anhydride in 300 mL of toluene. Under stirring conditions, add 3 g of 4-dimethylaminopyridine, and then heat to 75 °C and keep the temperature for reaction for 3 h. Under the conditions of a temperature of 40 °C and a vacuum of 0.08 MPa, concentrate under reduced pressure until the mass does not change to obtain a concentrate. Add the concentrate to a solution of 50% isopropanol, heat to 65 °C and stir to dissolve, then cool to 5 °C and stir at 100 rpm for crystallization for 4 h. Filter out the solid matter and dry until the mass does not change to obtain 60.3 g of a white solid, compound II-1;

[0092] In the said compound II-1, n = 1.

[0093] 2. Condensation acylation step

[0094] Dissolve 46 g of compound II-1 and 15.2 g of compound III-3 (3-diethylaminopropylamine) in 300 mL of N,N-dimethylformamide. Add 13.5 g of 1-hydroxybenzotriazole, 10 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 15 g of triethylamine. Under the temperature condition of 30 °C, stir at 200 rpm for 4 h. After the reaction is completed, obtain a reaction solution. Add 300 mL of purified water, and extract the reaction solution with ethyl acetate 3 times, 200 mL each time. Combine the organic phases. Then wash the organic phase with 80 mL of saturated sodium chloride solution once, separate the organic phase, and dry the organic phase with anhydrous sodium sulfate until the water content is between 1 - 2 wt%, and concentrate under reduced pressure until the mass does not change. Then add it to a 50% aqueous isopropanol solution, stir at 100 rpm for crystallization at 25 °C for 4 h, filter out the solid matter, and dry at 50 °C for 8 h to obtain 51.7 g of compound I-3.

[0095] In the structure of the compound I-3, n = 1, a = 3, b = c = 1. The specific structural formula is as follows:

[0096] .

[0097] The detection results of the 1H NMR and 13C NMR spectra of the compound I-3 are as follows:

[0098] 1 H NMR (600 Hz, CDCl3) δ 7.99 (s, 1H), 7.88 - 7.89 (d, J = 6 Hz, 2H), 7.60 - 7.62 (d, J = 12 Hz, 2H), 7.27 (d, J = 6 Hz, 1H), 5.87 (s, 1H), 5.17 (d, J = 6 Hz, 1H), 4.47 - 4.67 (m, 2H), 4.35 (m, 1H), 3.51 - 3.54 (t, J = 6 Hz, 12 Hz, 2H), 3.04 (s, 3H), 2.96 (t, 2H), 2.69 (t, 2H), 2.48 - 2.51 (m, 4H), 2.43 - 2.45 (t, J = 6 Hz, 2H), 1.69 - 1.74 (m, J = 6 Hz, 2H), 0.98 - 1.00 (t, J = 6 Hz, 6H).

[0099] 13 C NMR (600 Hz, CDCl3) δ 177.3 (1C), 164.4 (1C), 162.6 (1C), 147.4 (1C), 139.9 (1C), 127.5 (2C), 127.0 (2C), 81.8 (1C), 69.9 (1C), 66.2 (1C), 55.1 (1C), 50.3 (1C), 46.6 (2C), 44.5 (1C), 37.4 (1C), 31.5 (1C), 28.2 (1C), 25.1 (1C), 11.5 (2C).

[0100] This example also provides a florfenicol derivative, namely the aforementioned compound I-3.

[0101] Application Test Example 1

[0102] Animal in vivo absorption tests were respectively conducted on the florfenicol derivatives of Examples 1 - 3. Specifically, the florfenicol derivatives prepared in Examples 1 - 3 (i.e., compound I-1, compound I-2, compound I-3) were dissolved with water for injection, and formulated into florfenicol derivative injection solutions with a concentration of 500 mg / mL for standby. At the same time, a commercially available florfenicol injection solution with a concentration of 100 mg / mL was taken as a control.

[0103] Select healthy experimental pigs weighing 15 - 18 kg and intravenously inject them at a dose of 15 mg / kg body weight (both the florfenicol derivative injection and the commercially available florfenicol injection are administered at this dose). Within 30 h after administration, collect the blood of each experimental pig at regular intervals, separate the plasma, and measure the concentrations of the florfenicol derivative and florfenicol in the plasma.

[0104] The specific test results are shown in the appendix of the specification Figures 8 - 11 . Through the test results in the appendix of the specification Figures 8 - 10 It can be seen that after intravenous injection, the florfenicol derivative of the present invention can be rapidly converted into florfenicol in the animal body, and the concentration of florfenicol in the plasma increases rapidly; and it can maintain the blood drug concentration of florfenicol higher than the MIC value (greater than 3 μg / mL) within 0.5 - 22 hours after administration.

[0105] Through the test results in the appendix of the specification Figure 11 It can be seen that compared with florfenicol, the florfenicol derivative of the present invention has a higher peak blood drug concentration when converted into florfenicol in the body, and can maintain the blood drug concentration of florfenicol higher than the minimum inhibitory concentration (MIC value greater than 3 μg / mL) for a longer time (greater than 20 hours).

[0106] Unless otherwise specified, the percentages used in the present invention are all mass percentages.

[0107] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Florfenicol derivative, characterized in that, It has the following structural formula: （I） The structural formula of the florfenicol derivative is one of the following: n = 1, a = 2, b = c = 0; n = 1, a = 3, b = c = 0; n = 1, a = 3, b = c = 1.

2. Use of florfenicol derivatives, characterized in that, Use of the florfenicol derivative according to claim 1 in antibacterial infection drugs.

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