Preparation method and application of piperine analogue with antibacterial activity

Abstract

The invention relates to the field of chemical synthesis, and particularly provides a preparation method and application of a piperine analogue with antibacterial activity. The invention relates to a compound as shown in a formula I, and a stereoisomer or pharmaceutically acceptable salt or ester thereof, and the piperine analogue has an antibacterial effect, has the advantages of mild reaction, high process safety and the like, and has a wide application prospect in biochemical preparations, food industries and agriculture.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis and relates to a preparation method of a piperine analogue with antibacterial property and application thereof. Background Art

[0002] Natural products have become an inexhaustible source of active lead compound discovery due to the diversity and novelty of their chemical structures and biological activities. In recent years, studies on their derivatives have been carried out based on the structural characteristics of natural products. However, these derivatives are slightly inferior in activity performance and also have certain toxicity, which undoubtedly sets up many obstacles for the widespread application of these derivatives. Based on the structural characteristics of natural products, their analogs are designed, which have the advantages of reducing toxicity, increasing activity and yield. In the future, the core research direction in this field will be to develop analogs with specific groups so that they can act more accurately on specific targets, while improving the effect and reducing toxicity.

[0003] Piperine is the main extract of pepper, which has antibacterial, antioxidant, neuroprotective, anticonvulsant and anticancer effects, but its activity still cannot meet the needs of production and application. Based on the structural characteristics of piperine, designing and synthesizing piperine analogs is an important way to obtain more active compounds. However, due to the complexity of the compound structure, there is a delicate balance in the compound synthesis process, and specific target products can only be completed under specific conditions. There are few reports on piperine analogs in the prior art. Based on the structural characteristics of piperine and the basis of previous research, the present invention uses 4-hydroxy-3-methoxycinnamaldehyde and 1-acetylpyrrolidine to design and synthesize 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one with strong antibacterial properties through a simple synthesis method. Summary of the invention

[0004] The purpose of the present invention is to provide a piperine analogue and a preparation method and application thereof, wherein the piperine analogue has a chemical structural formula as shown in Formula I. The piperine analogue has an antibacterial effect, and its preparation process has the advantages of mild reaction, high process safety, high yield, etc., and has broad application prospects in the medical field, food industry and agriculture.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: The first aspect of the present invention provides a compound of formula I, or a pharmaceutically acceptable salt or ester thereof: .

[0006] The second aspect of the present invention provides a method for preparing a piperine analog. In a specific embodiment, the present invention technicians mix 4-hydroxy-3-methoxycinnamaldehyde of the structure shown in formula II and 1-acetylpyrrolidine of the structure shown in formula III in a molar ratio of 1:0.77, dissolve in ethanol, stir evenly, and then slowly drop 1.0 mmol / L sodium hydroxide solution. After reacting for 8 hours, adjust the pH value to 6-7 with 10% v / v hydrochloric acid solution, extract with ethyl acetate, dry over anhydrous magnesium sulfate, rotary evaporate, and separate and purify by silica gel column chromatography to obtain the piperine analog, 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one, whose chemical structure is shown in formula I. The specific synthesis route is shown as follows, and the yield of the main product reaches 50.2%: .

[0007] The technicians of the present invention also conducted a research experiment on the minimum inhibitory concentration of the piperine analogue prepared by the above preparation method on the test bacteria, and found that the piperine analogue had different degrees of inhibitory effect on Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa.

[0008] The third aspect of the present invention provides the use of the compound of formula I, or a pharmaceutically acceptable salt or ester thereof, in the preparation of an antibacterial agent for Escherichia coli, Staphylococcus aureus, Bacillus subtilis, or Pseudomonas aeruginosa.

[0009] The fourth aspect of the present invention provides a composition comprising as an active ingredient a compound of formula I, or a pharmaceutically acceptable salt or ester thereof, and one or more excipients.

[0010] Beneficial effects of the present invention: (1) The present invention successfully synthesized a piperine analogue with a completely new structure, 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one, enriching the types of piperine analogues. This unique structure gives it antibacterial properties, providing a new choice in the field of antibacterial compounds.

[0011] (2) The piperine analogs provided by the present invention can be used to develop new antibacterial agents in the field of biochemistry; they can be used as natural antibacterial agents in the food industry to extend the shelf life of food; in agriculture, they can be used to develop biological pesticides to effectively prevent and control bacterial diseases of crops, providing new technical means and development directions for multiple industries.

[0012] (3) The preparation method provided by the present invention uses 4-hydroxy-3-methoxycinnamaldehyde of the structure shown in formula II and 1-acetylpyrrolidine of the structure shown in formula III as raw materials, without a catalyst, and the solvent is a common solvent, so the raw materials are easily available.

[0013] (4) The preparation method provided by the present invention has mild and precisely controllable conditions, low energy consumption, high feasibility, and high process safety.

[0014] (5) The preparation method provided by the present invention has a main product yield of 50.2%, which is relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention provides a schematic diagram of the synthesis route of piperine analogs. DETAILED DESCRIPTION

[0016] The following is a further description of the concept of the present invention and the technical effects produced in conjunction with specific embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. The methods are conventional methods unless otherwise specified. The materials can be obtained from public commercial channels unless otherwise specified.

[0017] Example 1 Preparation of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one

[0018] 1.07 g (6.0 mmol) 4-hydroxy-3-methoxycinnamaldehyde, 0.52 g (4.6 mmol) 1-acetylpyrrolidine, and 20 mL ethanol were added to a 50 mL three-necked flask. After stirring evenly, 15 mL sodium hydroxide solution (1.0 mmol / mL) was slowly added dropwise. The mixture was reacted at room temperature for 8 hours. The pH value was adjusted to 6-7 with 10% v / v hydrochloric acid solution. The mixture was extracted with ethyl acetate, dried over anhydrous magnesium sulfate, evaporated, and purified by column chromatography. The yield was 50.2% (synthetic route is shown in the following example). Figure 1 as shown).

[0019] Example 2 Preparation of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one

[0020] 1.07 g (6.0 mmol) 4-hydroxy-3-methoxycinnamaldehyde, 0.52 g (4.6 mmol) 1-acetylpyrrolidine, and 20 mL ethanol were added to a 50 mL three-necked flask, stirred, reacted at room temperature for 8 hours, and the pH value was adjusted to 6-7 with 10% hydrochloric acid solution. Extracted with ethyl acetate, dried over anhydrous magnesium sulfate, rotary evaporated, and purified by column chromatography, with a yield of 1.2%, failed.

[0021] Example 3 Preparation of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one

[0022] 1.07 g (6.0 mmol) 4-hydroxy-3-methoxycinnamaldehyde, 0.52 g (4.6 mmol) 1-acetylpyrrolidine, and 20 mL ethanol were added to a 50 mL three-necked flask, stirred, and 20 mL sodium hydroxide solution (1.0 mmol / mL) was slowly added dropwise. The mixture was reacted at room temperature for 8 hours, and the pH value was adjusted to 6-7 with 10% hydrochloric acid solution. The mixture was extracted with ethyl acetate, dried over anhydrous magnesium sulfate, rotary evaporated, and purified by column chromatography with a yield of 31.8%.

[0023] Example 4 Preparation of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one

[0024] 1.07 g (6.0 mmol) 4-hydroxy-3-methoxycinnamaldehyde, 0.52 g (4.6 mmol) 1-acetylpyrrolidine, and 20 mL ethanol were added to a 50 mL three-necked flask, stirred, and 15 mL sodium hydroxide solution (1.0 mmol / mL) was slowly added dropwise, and reacted at room temperature for 8 hours. Extracted with ethyl acetate, dried over anhydrous magnesium sulfate, rotary evaporated, and purified by column chromatography, with a yield of 12.5%, failed.

[0025] Example 5 Preparation of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one

[0026] 1.07 g (6.0 mmol) 4-hydroxy-3-methoxycinnamaldehyde, 0.52 g (4.6 mmol) 1-acetylpyrrolidine, and 20 mL ethanol were added to a 50 mL three-necked flask, stirred, and 15 mL sodium hydroxide solution (1.0 mmol / mL) was slowly added dropwise. The mixture was reacted at room temperature for 8 hours, and the pH value was adjusted to 6-7 with 10% hydrochloric acid solution. The mixture was extracted with ethyl acetate, dried over anhydrous magnesium sulfate, and evaporated with a yield of 37.8%.

[0027] Example 6 Preparation of piperine

[0028] The white pepper was crushed and passed through a 40-mesh sieve to obtain pepper powder, and 80% V / V edible alcohol was added to obtain a mixed solution, and the mixed solution was heated to 60° C. and then kept heated at a constant temperature for 60 min, and subjected to leaching treatment to obtain a piperine extract, wherein the solid-liquid ratio of the pepper powder to 80% V / V edible alcohol was 0.04 g / mL; The piperine extract was concentrated and dried to prepare a 2 mg / mL piperine crude extract, which was loaded onto a column using HPD22 resin at a flow rate of 1.5 mL / min, and eluted with 90% V / V ethanol at a flow rate of 2.0 mg / mL to obtain a crude piperine product; The crude piperine was concentrated and dried, and 100% V / V edible alcohol was used as solvent to prepare a 200 mg / mL piperine extract. The piperine extract was crystallized at 4°C for 24 h, then recrystallized twice, the crystals were collected, and vacuum freeze-dried to obtain high-purity piperine.

[0029] Experiment 1 Minimum inhibitory concentration determination experiment

[0030] Add 6 samples of different mass concentrations to LB medium and shake well. The 6 samples are prepared by Examples 1-6. Each sample is prepared into a medium with a final concentration of 25.60, 12.80, 6.40, 3.20, 1.60, 0.80, 0.40, 0.20, 0.10, 0.05, and 0.025 mg / mL. Take 0.20 mL of 10 6 ~10 7 cfu / mL bacterial solution (Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa) was cultured in the culture medium at 37 °C for 24 h. The LB culture medium without sample solution was used as the blank control, and the lowest concentration of the sample solution without bacterial growth was used as the minimum inhibitory concentration (MIC).

[0031] The specific results of the experiment are shown in Table 1. In addition, the result of the blank control is 0, which indicates no contamination.

[0032] Table 1 Minimum inhibitory concentration of different groups against the test bacteria (mg / mL)

[0033] Note: Different letters indicate significant differences among different groups ( p >0.05) From Table 1, we can see that: (1) Compared with Examples 2 and 4, Example 1 shows that the key step in the preparation of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one is to add 1.0 mmol / L sodium hydroxide solution and 10% hydrochloric acid solution to adjust the pH value to 6-7. Indeed, any of these two steps cannot synthesize 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one.

[0034] (2) In comparison between Experimental Example 1 and Examples 3 and 5, the minimum inhibitory concentration of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one prepared by the method of the present invention was significantly reduced. Changing the amount of sodium hydroxide added and omitting the column chromatography separation step were not conducive to the antibacterial activity of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one.

[0035] (3) Comparing Experimental Example 1 with Example 6, the minimum inhibitory concentration of 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one prepared by the method of the present invention is significantly reduced, indicating that 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one has a better antibacterial effect.

[0036] The sample prepared in Experimental Example 1 was subjected to nuclear magnetic resonance and mass spectrometry analysis, and the results were as follows: 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one had the following nuclear magnetic hydrogen spectrum characteristics: 1H NMR (300 MHz, CDCl3) δ:9.15 (s, 1H), 7.36 (d, J = 3.0 Hz, 1H),7.11-6.99 (m, J = 6.0 Hz, 1H), 6.71-6.79 (m, J =12.0 Hz, 1H), 5.42 (d, 1H), 3.83 (s, 3H), 3.28 (s, 2H), 1.81 (s,2H).

[0037] 5-(4-Hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one has the following high resolution mass spectrometry characteristics: HRMS [M+H] + : The theoretical value is 273.1365, and the measured value is 273.1366.

[0038] Although the present invention has been described in detail above by means of general description, specific implementation methods and experiments, the present invention is not limited to the above embodiments, and some modifications or improvements can be made on the basis of the present invention, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A compound of formula I, or a pharmaceutically acceptable salt or ester thereof: 。 2. A piperine analogue with antibacterial properties, characterized in that The piperine analog is a compound shown in formula I. The preparation method of the piperine analog is as follows: 4-hydroxy-3-methoxycinnamaldehyde shown in formula II and 1-acetylpyrrolidine shown in formula III are mixed in a molar ratio of 1:0.77 and dissolved in ethanol, stirred evenly, and then 1.0 mmol / L sodium hydroxide solution is slowly added dropwise. After reacting for 8 hours, the pH value is adjusted to 6-7 with a 10% v / v hydrochloric acid solution, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, rotary evaporated, and separated and purified by silica gel column chromatography to obtain the piperine analog 5-(4-hydroxy-3-methoxy)phenyl-1-pyrrolidinyl-2,4-pentadien-1-one, the specific chemical structure of which is shown in formula I: 。 3. Use of the compound of formula I according to claim 1, or a pharmaceutically acceptable salt or ester thereof, in the preparation of an antibacterial agent for Escherichia coli, Staphylococcus aureus, Bacillus subtilis, or Pseudomonas aeruginosa.

4. A pharmaceutical composition comprising as an active ingredient a compound of formula I according to claim 1, or a pharmaceutically acceptable salt or ester thereof, and one or more excipients.

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