An N-methyl diphenylpiperidine derivative, and a preparation method and application thereof

Abstract

The application belongs to the technical field of medicine and chemical industry, and particularly relates to N-methyl diphenylpiperidine derivatives, a preparation method and application thereof. The N-methyl diphenylpiperidine derivative shown in formula I has a bacterial quorum sensing regulation effect, has no influence on the growth of various sensitive bacteria and drug-resistant bacteria, and is not easy to induce drug resistance. Research shows that the N-methyl diphenylpiperidine derivative has a strong inhibitory effect on Pseudomonas aeruginosa biofilm; in combination with an antibacterial drug, the drug-resistant bacteria have a significantly improved sensitivity to antibiotics, and the drug efficacy is enhanced, so that the N-methyl diphenylpiperidine derivative can be used for preparing a drug for treating diseases caused by gram-negative bacteria. In addition, the preparation method of the compound is simple, raw materials are cheap and easy to obtain, and reaction conditions are mild, so that the compound has good economic efficiency and an industrial production prospect.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical and chemical technology, specifically relating to N-methylbiphenylpiperidine derivatives, their preparation methods, and applications. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] During bacterial growth, bacteria continuously produce chemical signaling molecules and secrete them into the surrounding environment. When the concentration of these signaling molecules reaches a certain threshold, they regulate / activate the expression of bacterial-related genes, such as bioluminescence, biofilm formation, and toxic gene expression, in order to adapt to environmental changes. This regulatory system is known as the bacterial quorum sensing (QS) signaling system.

[0004] In the 1970s, scientists discovered that natural or synthetic quorum sensing modulators (including agonists or inhibitors) could interfere with signal transduction systems and regulate the expression of harmful bacterial genes. Bacterial quorum sensing modulators do not interfere with the normal physiological functions of cells in the body; they only regulate the expression of harmful genes in pathogenic bacteria, rendering them incapable of causing disease. This is considered a new direction in the development of antibacterial drugs. Among them, bacterial quorum sensing inhibitors can be used in combination with antibiotics to increase the sensitivity of pathogenic bacteria to antibiotics and enhance drug efficacy.

[0005] Among them, *Pseudomonas aeruginosa*, a common opportunistic pathogen in clinical practice, causes serious infections in immunocompromised individuals. Its quorum sensing regulatory network is mainly composed of… las , rhl and pqs Composed of three functionally complementary subsystems, a complex network of hierarchical regulation is formed, jointly participating in key physiological processes such as bacterial virulence factor expression and biofilm formation. Therefore, the development of quorum sensing inhibitors targeting the Pseudomonas aeruginosa quorum sensing system holds great promise. Unlike traditional antibiotics, quorum sensing regulation reduces pathogenicity without inhibiting bacterial growth by suppressing the production of bacterial virulence factors, thus reducing the development of drug resistance and offering hope for the development of novel antibacterial drugs. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide an N-methylbiphenylpiperidine derivative, its preparation method, and its application. This invention provides an N-methylbiphenylpiperidine derivative capable of targeting and inhibiting *Pseudomonas aeruginosa*. pqs Quorum sensing systems can significantly reduce the biofilm formation capacity of bacteria without inhibiting their growth and can be used as antibacterial sensitizers.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: The first aspect of the present invention provides N-methylbiphenylpiperidine derivatives of Formula I, their racemic or optical isomers, pharmaceutically acceptable salts, solvates, or hydrates thereof, the chemical structure of which is shown below:

[0008] Formula I; Wherein, R is selected from aryl and aryl heterol; The aryl group is selected from one or more of phenyl, benzyl, phenethyl, naphthyl, anthracene, phenanthryl, indene, fluorenyl, and acenaphthene. The aromatic heterol group is selected from one or more of pyrroleyl, imidazolyl, oxazolyl, isoxazolyl, thiophenyl, thiazolyl, pyridyl, pyrazinyl, furanyl, pyridazinyl, morpholinyl, pyrazolyl, indolyl, pyrimidinyl, benzothiazolyl, benzofuranyl, benzimidazolyl, benzoxazolyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, purinyl, carbazolyl, phenothiazinyl, and phenothiazinyl. The above groups may be optionally mono- or poly-substituted by substituents selected from the following: alkyl, alkoxy, fluoroalkyl, halogen, nitro, hydroxy, and cyano.

[0009] In this invention, the R substitution site is ortho, meta, and / or para; the alkyl group in alkyl, alkoxy, and fluoroalkyl is a straight-chain or branched alkyl group with 1 to 12 C atoms; in fluoroalkyl, the number of hydrogen atoms substituted is one or more.

[0010] Furthermore, R is selected from one of methoxyphenyl, fluorophenyl, trifluoromethylphenyl, methylphenyl, chlorophenyl, hydroxyphenyl, biphenyl, and dimethoxyphenyl.

[0011] Furthermore, the chemical structure of Formula I is selected from any one of the following compounds D1 to D16: .

[0012] The second aspect of the present invention provides a method for preparing the N-methylbiphenylpiperidine derivatives, racemates or optical isomers thereof, pharmaceutically acceptable salts thereof, solvates or hydrates thereof, as described in the first aspect, the method comprising the following steps: reacting the intermediate shown in Formula 4 with a phenethylamine derivative via an amide condensation reaction to obtain the product; the chemical structure of Formula 4 is shown below:

[0013] The phenethylamine derivatives include 3-methoxyphenethylamine, 4-methoxyphenethylamine, 3-fluorophenethylamine, 4-fluorophenethylamine, 4-methylphenethylamine, 4-chlorophenethylamine, o-fluorophenethylamine, 3-chlorophenethylamine, 2-(4-trifluoromethylphenyl)ethylamine, 3-(trifluoromethyl)phenethylamine, o-methoxyphenethylamine, 3-methylphenethylamine, 3-hydroxyphenethylamine, 3,4-dimethoxyphenethylamine, 2-(4-biphenyl)ethylamine, and 2,3-dimethoxyphenethylamine.

[0014] Furthermore, the synthetic route for preparing the intermediate shown in Formula 4 is as follows: .

[0015] A third aspect of the invention provides a pharmaceutical composition comprising an N-methylbiphenylpiperidine derivative of Formula I as described in the first aspect, its racemic or optical isomer, its pharmaceutically acceptable salt, solvate or hydrate, and optionally one or more pharmaceutically acceptable carriers and excipients.

[0016] Furthermore, the pharmaceutical composition also contains at least one antibiotic.

[0017] Furthermore, the antibiotic is selected from at least one of tetracycline, amoxicillin, cefixime, vancomycin, norfloxacin, tobramycin, clarithromycin, and ciprofloxacin.

[0018] The fourth aspect of the invention provides the use of N-methylbiphenylpiperidine derivatives of Formula I as described in the first aspect, their racemic or optical isomers, pharmaceutically acceptable salts, solvates or hydrates thereof, in the preparation of medicaments as bacterial quorum sensing modifiers.

[0019] When N-methylbiphenylpiperidine derivatives are used as bacterial quorum sensing inhibitors, they can inhibit the QS system of Gram-negative bacteria, thereby inhibiting bacterial biofilm formation and reducing the expression of bacterial virulence factors. Therefore, the bacterial quorum sensing inhibitors described in this invention can be used not only as bacteriostatic agents, bacteriostatic drugs, or antibacterial drugs for therapeutic purposes, but also as chemical preparations for scientific research on the inhibition of bacterial biofilms.

[0020] Furthermore, the bacteria are Gram-negative or Gram-positive bacteria; preferably Gram-negative bacteria.

[0021] Furthermore, the Gram-negative bacteria are selected from Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus, Shigella, Brucella, Haemophilus influenzae, Parainfluenza bacteria, Moraxella catarrhalis, Acinetobacter spp., Yersinia spp., Pasteurella spp., Shigella spp., Bordetella pertussis, Bordetella parapertussis, Parahemolyticus, Legionella pneumophila, or Vibrio cholerae.

[0022] The fifth aspect of the invention provides the use of N-methylbiphenylpiperidine derivatives of Formula I as described in the first aspect, their racemic or optical isomers, pharmaceutically acceptable salts, solvates or hydrates thereof, in the preparation of medicaments for the prevention and / or treatment of diseases caused by bacterial infections.

[0023] Furthermore, the bacteria are Gram-negative or Gram-positive bacteria; in one specific embodiment of the present invention, the bacteria are Gram-negative bacteria.

[0024] Furthermore, the Gram-negative bacteria are selected from one or more of the following: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus, Shigella, Brucella, Haemophilus influenzae, Parainfluenza bacteria, Moraxella catarrhalis, Acinetobacter spp., Yersinia spp., Pasteurella spp., Shigella spp., Bordetella pertussis, Bordetella parapertussis, Parahaemolyticus, Legionella pneumophila, and Vibrio cholerae.

[0025] Furthermore, the diseases caused by bacterial infection include endocarditis, peritonitis, gastroenteritis, cholecystitis, cystitis, diarrhea, empyema, or sepsis.

[0026] The sixth aspect of the present invention provides the use of N-methylbiphenylpiperidine derivatives of Formula I as described in the first aspect, their racemic or optical isomers, pharmaceutically acceptable salts, solvates or hydrates thereof, in the preparation of antimicrobial sensitizers.

[0027] Furthermore, the antibacterial sensitizer is used to enhance the sensitivity of bacteria to antibiotics; the antibiotic is selected from at least one of tetracycline, amoxicillin, cefixime, vancomycin, norfloxacin, tobramycin, clarithromycin, and ciprofloxacin.

[0028] Furthermore, the bacteria are Gram-negative or Gram-positive bacteria; in one specific embodiment of the present invention, the bacteria are Gram-negative bacteria.

[0029] Furthermore, the Gram-negative bacteria are selected from one or more of the following: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus, Shigella, Brucella, Haemophilus influenzae, Parainfluenza bacteria, Moraxella catarrhalis, Acinetobacter spp., Yersinia spp., Pasteurella spp., Shigella spp., Bordetella pertussis, Bordetella parapertussis, Parahaemolyticus, Legionella pneumophila, and Vibrio cholerae.

[0030] The beneficial effects of this invention are: The N-methylbiphenylpiperidine derivatives provided by this invention significantly reduce the expression of virulence factors such as biofilms by inhibiting the quorum sensing system of *Pseudomonas aeruginosa* without affecting normal bacterial growth, thereby effectively reducing the pathogenicity of the bacteria. They can be used alone or in combination with antibiotics to enhance anti-infective effects, and are particularly suitable for the prevention and treatment of infectious diseases caused by drug-resistant Gram-negative bacteria. Furthermore, the preparation method of the compounds of this invention is simple, the raw materials are inexpensive and readily available, and the reaction conditions are mild, demonstrating good economic viability and prospects for industrial production. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 The results of investigating the inhibitory activity of compounds D1-D16 on biofilm formation of Pseudomonas aeruginosa PAO1 are shown in the figure. Figure 2 The diagram shows the synergistic antibacterial effects of compounds D1 and D14 with the antibacterial agents tobramycin (TOB) or clarithromycin (CLA); among them, Figure 2 A shows the synergistic antibacterial effect of compound D1 and TOB. Figure 2 B represents the synergistic antibacterial effect of compound D14 and TOB. Figure 2 C represents the synergistic antibacterial effect of compound D1 and CLA. Figure 2 D represents the synergistic antibacterial effect of compound D14 and CLA. Figure 2 E represents the synergistic antibacterial effect of compound D1 and CIP. Figure 2 F is a graph showing the synergistic antibacterial effect of compound D14 and CIP; Figure 3 The figure shows the results of investigating the inhibitory activity of compound D1 against GFP reporter strains; where, Figure 3 A represents PAO1- pqsA - gfp Figure showing the results of the inhibitory activity assessment; Figure 3 B represents PAO1- rhlA - gfp Figure showing the results of the inhibitory activity assessment; Figure 3 C represents the PAO1- lasB - gfp Figure showing the results of the inhibitory activity assessment; Figure 3 D represents the reaction of PAO1- gfp The results of the investigation of inhibitory activity are shown in the figure. Detailed Implementation

[0033] The present invention will be further illustrated below with specific intermediates and embodiments. However, it should be understood that these intermediates and embodiments are only used for more detailed and specific illustration, and should not be construed as limiting the present invention in any way.

[0034] The various phrases and terms used in this invention have their general meanings known to those skilled in the art, but where there are special definitions herein, the meanings defined herein shall prevail.

[0035] As used herein, the term "halogen" has the general meaning known in the art and generally includes F, Cl, Br, I, and may also include their isotopic forms, preferably F and Cl in this invention.

[0036] As used herein, the terms “racemate” and “optical isomer” have their general meanings as known in the art.

[0037] According to the present invention, suitable pharmaceutically acceptable salts or hydrates of compounds of general formula I or their stereoisomers thereof are included, but not limited to, salts of compounds of general formula I with inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, hydrobromic acid, and nitric acid, as well as salts with various organic acids such as maleic acid, malic acid, fumaric acid, succinic acid, tartaric acid, citric acid, acetic acid, lactic acid, methanesulfonic acid, p-toluenesulfonic acid, palmitic acid, etc. Some compounds of the present invention may crystallize or recrystallize with water or various organic solvents, in which case various solvates may be formed. The present invention includes those stoichiometric solvates, including hydrates, and also includes compounds containing a variable amount of water formed during preparation by low-pressure sublimation drying.

[0038] According to the present invention, stereoisomers of the compounds of Formula I refer to compounds that may exist in the form of optical isomers or cross-isomers. The present invention includes all forms of their existence, particularly pure isomers. Different isomeric forms can be isolated or separated from other isomers by various conventional means, or a certain isomer can be obtained by various conventional synthetic methods or stereospecific or asymmetric synthetic methods. Since the compounds of Formula I are for pharmaceutical purposes, it is understood that they are preferably provided in pure form, for example, at least 60% purity, more preferably 75%, better 85%, and most preferably at least 98% purity (% refers to weight percentage). Methods for preparing impure compounds can be used for more pure forms in pharmaceutical compositions. These less pure products contain at least 1%, more preferably 5%, and better preferably at least 10% of the compound as represented by general Formula I or a pharmaceutically acceptable derivative thereof.

[0039] According to the present invention, the above-mentioned compound of general formula I can be prepared by the following typical exemplary method, the method comprising the following steps: 1) Ethyl piperidine-4-carboxylate was dissolved in dichloromethane, and potassium carbonate and tetrabutylammonium iodide were added at room temperature. The mixture was stirred, and benzyl bromodimethyl ester diluted with acetonitrile was added. A nucleophilic substitution reaction was carried out at room temperature. After the reaction was completed, the mixture was filtered, and the filtrate was concentrated and separated by silica gel column chromatography to obtain the intermediate shown in Formula 2.

[0040]

[0041] 2) The intermediate shown in Formula 2 was dissolved in a mixed solution of dioxane and water, and the temperature was gradually raised from room temperature to 70-90°C. Tetraphenylphosphine palladium, potassium carbonate, and 3-chloro-4-isooxypropylphenylboronic acid were added, and a coupling reaction was carried out under nitrogen protection. The reaction was monitored by TLC. After the reaction was completed, the mixture was cooled to room temperature, filtered, and purified by silica gel column chromatography to obtain the intermediate shown in Formula 3.

[0042]

[0043] 3) Dissolve the intermediate shown in Formula 3 in a mixed solution of tetrahydrofuran and water, add excess potassium hydroxide, gradually raise the temperature from room temperature to 60~80 ℃, reflux overnight, monitor the reaction by TLC, after the reaction is complete, add 1.5~2.5 M hydrochloric acid solution to adjust the pH of the system to weakly acidic, observe the formation of a white precipitate after standing, filter, collect the white precipitate, and obtain the intermediate shown in Formula 4.

[0044]

[0045] (4) The intermediate shown in Formula 4 was dissolved in dichloromethane, and 1-hydroxybenzotriazole, benzotriazole-N,N,N',N'-tetramethylurea hexafluorophosphate and N,N-diisopropylethylamine were added sequentially at room temperature. The mixture was stirred, and then different substituted alkyl side chains (different phenylethylamine derivatives) were added. An amide condensation reaction occurred at room temperature overnight. The reaction was monitored by TLC. After the reaction was completed, a small amount of water was added for washing. The mixture was extracted with ethyl acetate, the organic phase was concentrated, and the mixture was purified by silica gel column chromatography to obtain the compound shown in Formula I.

[0046]

[0047] Formula I This invention also relates to pharmaceutical compositions comprising at least one compound of formula I and at least one pharmaceutically acceptable carrier or excipient. A compound of formula I or a pharmaceutically acceptable salt thereof may be used alone or together with a pharmaceutically acceptable carrier or excipient in the form of a pharmaceutical composition. When used in the form of a pharmaceutical composition, an effective dose of the compound of formula I of this invention or a pharmaceutically acceptable salt or hydrate thereof, along with one or more pharmaceutically acceptable carriers or diluents, is typically combined to form a suitable administration or dosage form. This procedure includes mixing, granulating, compressing, or dissolving the components in a suitable manner.

[0048] The pharmaceutical composition of the present invention can be administered in any of the following ways: orally, by spray inhalation, rectal administration, nasal administration, vaginal administration, local administration, parenteral administration such as subcutaneous, intravenous, intramuscular, intraperitoneal, intrathecal, intraventricular, intrasternal, or intracranial injection or infusion, or by means of an external reservoir, wherein oral, intramuscular, intraperitoneal, or intravenous administration is preferred.

[0049] The pharmaceutical carriers contained in the pharmaceutical compositions of the present invention include, but are not limited to: ion exchangers, alumina, aluminum stearate, lecithin, serum proteins such as human serum albumin, buffering substances such as phosphates, glycerol, sorbic acid, potassium sorbate, a mixture of partial glycerides of saturated vegetable fatty acids, water, salts or electrolytes such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinylpyrrolidone, cellulose substances, polyethylene glycol, carboxymethyl cellulose, polyacrylate, beeswax, lanolin, etc. The carrier content in the pharmaceutical composition can be from 1% to 98% by weight, typically approximately 80% by weight. For convenience, local anesthetics, preservatives, buffers, etc., can be directly dissolved in the carrier.

[0050] Oral dosage forms such as tablets and capsules may contain excipients such as binders, like syrups, gum arabic, sorbitol, astragalus gum, or polyvinylpyrrolidone; fillers such as lactose, sucrose, corn starch, calcium phosphate, sorbitol, glycine; lubricants such as magnesium stearate, talc, polyethylene glycol, silica; disintegrants such as potato starch; or acceptable humectants such as sodium lauryl sulfate. Tablets may be coated using pharmaceutically known methods.

[0051] The pharmaceutical compositions of the present invention in oral liquid form can be formulated as suspensions, solutions, emulsions, syrups, or elixirs of water and oil, or as dry products to be replenished with water or other suitable media before use. Such liquid formulations may contain conventional additives such as suspending agents, sorbitol, cellulose methyl ether, glucose syrup, gels, hydroxyethyl cellulose, carboxymethyl cellulose, aluminum stearate gel, hydrogenated edible oils, emulsifiers such as lecithin, sorbitan monooleate, gum arabic; or non-aqueous carriers (possibly containing edible oils such as almond oil), fats such as glycerin, ethylene glycol, or ethanol; preservatives such as methylparaben or propylparaben, sorbic acid. Flavoring or coloring agents may be added if desired. Suppositories may contain conventional suppository bases such as cocoa butter or other glycerides. For parenteral administration, liquid dosage forms are typically made from the compound and at least one sterile or sterile carrier. Water is the preferred carrier. Depending on the chosen carrier and drug concentration, the compound can be either soluble in the carrier or prepared as a suspension. When preparing an injectable solution, the compound is first dissolved in water, filtered, sterilized, and then packaged into sealed bottles or ampoules. For topical application to the skin, the compounds of this invention can be formulated as suitable ointments, lotions, or creams, wherein the active ingredient is suspended or dissolved in one or more carriers. Carriers that can be used in ointment formulations include, but are not limited to: mineral oil, liquid petrolatum, white petrolatum, propylene glycol, polyethylene oxide, polypropylene oxide, emulsified wax, and water; carriers that can be used in lotions and creams include, but are not limited to: mineral oil, sorbitan monostearate, Tween 60, hexadecyl ester wax, hexadecene aromatic alcohol, 2-octyldodecyl alcohol, benzyl alcohol, and water. Depending on the route of administration, the composition may contain 0.1% by weight, or more preferably 10-60% by weight of the active ingredient. However, when the composition is in unit dosage form, each unit preferably contains 50-500 mg of the active ingredient. Depending on the route of administration and frequency of administration, the appropriate therapeutic dose for adults may be 100-3000 mg per day.

[0052] It must be recognized that the optimal dosage and interval for a compound of formula I are determined by the severity of the disease or symptoms, the nature of the compound, and conditions such as the form, route and site of administration, and the specific mammal being treated. This optimal dosage can be determined by the clinician.

[0053] This invention provides a general and / or specific description of the materials and methods used in the experiments. While many of the materials and methods used to achieve the objectives of this invention are well known in the art, they are still described in as much detail as possible herein. It will be apparent to those skilled in the art that, unless otherwise stated, the materials and methods used in this invention are well known in the art.

[0054] The present invention will be further described in detail below with reference to specific embodiments.

[0055] Example 1: Synthesis of Intermediate 2

[0056] Ethyl piperidine-4-carboxylate (1.00 g, 6.4 mmol) was dissolved in 15 mL of dichloromethane. Potassium carbonate (1.76 g, 12.7 mmol) and tetrabutylammonium iodide (0.23 g, 0.6 mmol) were added at room temperature, and the mixture was stirred for 15 min. Then, benzyl bromide diluted with acetonitrile (1.74 g, 10.2 mmol) was added, and the mixture was stirred at room temperature for 1 h. After the reaction was complete, the mixture was filtered, and the filtrate was concentrated and separated by silica gel column chromatography (volume ratio, ethyl acetate:petroleum ether = 1:3) to obtain intermediate 2.

[0057] Example 2 Synthesis of Intermediate 3

[0058] Intermediate 2 (2.46 g, 7.6 mmol) was dissolved in 30 mL of a dioxane:water mixture (10:1 v / v), and the temperature was gradually increased from room temperature to 80 °C. Tetraphenylphosphine palladium (0.40 g, 0.5 mmol), potassium carbonate (4.83 g, 34.9 mmol), and 3-chloro-4-isooxypropylphenylboronic acid (1.93 g, 15.8 mmol) were added. The reaction was carried out under nitrogen protection for 24 h, and the reaction was monitored by TLC. After the reaction was completed, the mixture was cooled to room temperature, filtered, and purified by silica gel column chromatography (dichloromethane:methanol = 30:1 v / v) to obtain intermediate 3.

[0059] Example 3 Synthesis of Intermediate 4

[0060] Intermediate 3 (2.24 g, 6.3 mmol) was dissolved in 15 mL of a tetrahydrofuran:water mixture (volume ratio 1:1), and excess potassium hydroxide (15.00 g, 267.3 mmol) was added. The mixture was gradually heated from room temperature to 70 °C and refluxed overnight. The reaction was monitored by TLC. After the reaction was completed, 2 M hydrochloric acid solution was added to adjust the pH of the system to weakly acidic. After standing, a white precipitate was observed to form. The precipitate was filtered and collected, which was intermediate 4.

[0061] Example 4 Synthesis of Compound D1

[0062] Intermediate 4 (0.5 mmol) was dissolved in 15 mL of dichloromethane. At room temperature, 1-hydroxybenzotriazole (0.6 mmol), benzotriazole-N,N,N',N'-tetramethylurea hexafluorophosphate (0.6 mmol), and N,N-diisopropylethylamine (2.2 mmol) were added sequentially. The mixture was stirred for 30 min, and then different phenethylamine derivatives (0.7 mmol) were added. The reaction was allowed to proceed overnight at room temperature, and the reaction was monitored by TLC. After the reaction was complete, the mixture was washed with a small amount of water, extracted with ethyl acetate, and the organic phase was concentrated. The organic phase was then purified by silica gel column chromatography (dichloromethane:methanol = 15:1, v / v) to obtain the target compounds D1–D16. The structural confirmation information of the compounds is shown in Table 1.

[0063] The preparation process of compounds D1 to D16 is the same as that of D1, only requiring the corresponding replacement of the raw materials.

[0064] Table 1. Structural confirmation information for compounds D1-D16

[0065] Example 5: Effects of derivatives D1-D16 on biofilm formation in Pseudomonas aeruginosa PAO1 This embodiment measures the effect of target compounds (D1~D16) on Pseudomonas aeruginosa (…). Pseudomonas aeruginosa , P. aeruginosa The effect of PAO1 on biofilm formation was investigated to characterize the QS inhibitory effect of the compounds of this invention. The bacterial strains used were obtained from the China General Microbiological Culture Collection Center (CGMCC).

[0066] 1. Experimental Methods Resuscitate P. aeruginosa PAO1, subculture it into LB broth, and incubate it in a 37 °C incubator for 20 h. Dilute the subcultured PAO1 to OD using ABTGC medium. 620= 0.05. Add an appropriate amount of the above bacterial suspension and the stock solution of the test compound to a 96-well plate, dilute twofold to 128 μg / mL, resulting in 100 μL per well. Perform three replicates for each sample. Three types of controls were set up simultaneously: ① Dimethyl sulfoxide (DMSO) negative control group: DMSO solvent was serially diluted and mixed with the diluted bacterial suspension, 100 μL per well, three replicates. The entire process was synchronized with the test samples to characterize the normal biofilm formation level of the strain without drug interference; ② Azithromycin (AZM) positive control group: Azithromycin was serially diluted twofold as the test derivative, with the same bacterial suspension system, parallel setup, and experimental operation. This served as a positive reference for biofilm inhibition activity, verifying the reliability of the detection system; ③ Blank control group: Contained only ABTGC medium and DMSO, without the test strain. The entire staining and detection process was completed simultaneously to subtract the system's background absorbance. The wells were sealed with 200 μL of broth to prevent edge effects. Incubate at 37 °C for 24 h. Afterward, discard the liquid in the wells, being careful not to let it touch the sides and bottom to avoid damaging the biofilm and affecting the experimental results. Wash twice with 150 μL of PBS buffer, then add 100 μL of anhydrous methanol and retain for 30 min to fix the biofilm. Discard the methanol and dry in a 30 °C oven. Add 100 μL of 0.1% crystal violet solution and retain for 15 min to stain the biofilm. Discard the stain and wash the 96-well plate repeatedly with PBS until the washing water is colorless. Dry the 96-well plate again. Finally, add 100 μL of 33% glacial acetic acid solution to the 96-well plate, shake for 5-10 min, and after the biofilm is completely dissolved, measure the OD. 570 The biofilm formation inhibition rate was 1-(Abs) sample -Abs blank ) / (Abs negative -Abs blank ) × 100%.

[0067] 2. Experimental Results Depend on Figure 1 Among compounds D1–D16, compounds D1 and D14 exhibited excellent biofilm inhibition capabilities, with inhibition rates of 74.09 ± 5.32% and 79.77 ± 3.15% against *Pseudomonas aeruginosa* PAO1 at 128 µg / mL, respectively, both significantly different from the DMSO negative control group (P<0.001). From a structure-activity relationship perspective, electron-donating methoxy substitutions at the ortho and para positions of the benzene ring (D1, D14) showed the best activity, while electron-withdrawing halogens, trifluoromethyl groups, and multiple substituents all reduced activity, and overall, ortho-substitution was superior to para-substitution. These results indicate that N-methylbiphenylpiperidine derivatives have a strong inhibitory effect on *Pseudomonas aeruginosa* PAO1 biofilm.

[0068] Example 6 Synergistic antibacterial effect of derivatives D1 and D14 with antibacterial agents 1. Experimental Methods Resuscitate Pseudomonas aeruginosa PAO1 and streak it onto solid nutrient agar medium. Incubate the medium at 37°C for 20 h. Add 6-8 mL of physiological saline to a turbidity test tube. Use an inoculation loop to transfer healthy subculture colonies into the turbidity test tube and mix to a final volume of 1.5 × 10⁻⁶. 8 CFU / mL. Take 2 mL of bacterial suspension and add 18 mL of physiological saline to obtain bacterial solution. Take a sterile 96-well plate and add 187.5 µL of LB liquid medium to column 2, and 95 µL of liquid medium to columns 3-6. Add 10 µL of antibiotic stock solution to column 2, and 5 µL of antibiotic stock solution to columns 3-6. Add 2.5 µL of the test compound to column 2 until the compound concentration reaches 32 μg / mL. Mix the medium and compound in column 2, and add 100 µL to the next column, mixing well. Repeat this mixing process until column 5, discarding any excess 100 µL. At this point, each column has a volume of 100 µL. The drug concentration decreases by a factor of 128-16 μg / mL from columns 2-5. The antibiotics used are tobramycin, clarithromycin, and ciprofloxacin (final concentrations of 1 / 4 MIC, 1 / 8 MIC, 1 / 16 MIC, 1 / 32 MIC, and 1 / 64 MIC). Add 5 µL of bacterial culture to columns 2-6. A negative control is set up in each group (90 μL of LB liquid medium and 5 µL of DMSO solvent). 5 μL of diluted bacterial solution (total volume 100 μL per well) was used to seal the wells with 200 μL of LB medium to prevent edge effects and serve as a blank control. Three replicates were set up for each sample. The 96-well plate was incubated at 37 ℃ for 20 h. After incubation, the plate was shaken for 30 s in a microplate reader, and the optical density (OD600) was read. The bacterial mortality rate was calculated as 1-(Abs) sample -Abs blank ) / (Abs negative -Abs blank ) × 100%.

[0069] 2. Experimental Results Depend on Figure 2 It is known that different concentrations of compounds D1 and D14, when used in combination with sub-inhibitory concentrations of clarithromycin, are more effective at inhibiting bacterial activity than the same concentration of antibiotics used alone.

[0070] in, Figure 2 A indicates that, at a TOB concentration of 1 / 4 MIC, the combination with compound D1 at 128 μg / mL resulted in an inhibition rate of 82.94%. Figure 2B indicates that, at a TOB concentration of 1 / 4 MIC, the combination with compound D14 at 128 μg / mL resulted in an inhibition rate of 54.61%. Figure 2 C indicates that, at a CLA concentration of 1 / 4 MIC, combination with compound D1 at 128 μg / mL can achieve an inhibition rate of 90.17%. Figure 2 D indicates that, at a CLA concentration of 1 / 4 MIC, the combination with compound D14 at 128 μg / mL resulted in an inhibition rate of 86.88%. Figure 2 E indicates that, at a CIP concentration of 1 / 64 MIC, combination with compound D1 at 128 μg / mL can achieve an inhibition rate of 79.97%. Figure 2 F indicates that, at a CLA concentration of 1 / 64 MIC, combination with compound D14 at 128 μg / mL resulted in an inhibition rate of 62.03%.

[0071] Example 7: Derivative D1 on GFP reporter strain PAO1- lasB-gfp , PAO1- rhlA-gfp , PAO1- pqsA- gfp and PAO1- gfp Inhibitory activity This embodiment measures the effect of target compound D1 on the GFP reporter strain PAO1- lasB-gfp PAO1- rhlA-gfp PAO1- pqsA-gfp and PAO1- gfp Inhibitory activity was assessed to characterize the targeting of the compounds of this invention to quorum sensing systems. The fluorescent reporter strain used in the experiment was provided by Professor Chen Weimin's research group at Jinan University.

[0072] 1. Experimental Methods A two-fold serial dilution method was used in 96-well black transparent plates. The test compounds were serially diluted with ABTGC medium to achieve a concentration twice the preset value. After dilution, the mixture was thoroughly shaken to mix. Subsequently, an equal volume of overnight incubation solution was added to each well, followed by dilution to OD. 600 The bacterial culture solution was prepared at a concentration of 0.05 μL, and 200 μL of liquid culture medium was added to the outer wells of the 96-well plate for sealing. The 96-well plate was placed in a multimode microplate detection system, with the temperature set at 37 °C, excitation wavelength at 485 nm, and emission wavelength at 528 nm. Fluorescence intensity and OD600 were measured every 15 min for 10 consecutive hours. The effect of the compound on the three QS pathways was determined by calculating the ratio of fluorescence intensity to absorbance.

[0073] 2. Experimental Results Depend on Figure 3 It can be seen that among them Figure 3Results A showed that as the concentration of compound D1 increased, PAO1... -pqsA-gfp The fluorescence intensity showed a significant concentration-dependent decrease; Figure 3 Results B showed that as the concentration of compound D1 increased, PAO1- rhlA- gfp The fluorescence intensity did not show a significant concentration-dependent decrease; Figure 3 Results C showed that as the concentration of compound D1 increased, PAO1... -lasB-gfp The fluorescence intensity did not show a significant concentration-dependent decrease; Figure 3 Results D showed that as the concentration of compound D1 increased, PAO1... -gfp The fluorescence intensity did not show a significant concentration-dependent decrease.

[0074] The results showed that compound D1 could inhibit PAO1- in a concentration-dependent manner. pqsA - gfp Fluorescent expression indicates that the compound can target quorum sensing. pqs Instead of acting directly on green fluorescent protein, this experimental result more directly demonstrates the targeting of the newly synthesized compound D1 to the quorum sensing system, indicating that the newly synthesized compound D1 can be effectively used as a quorum sensing inhibitor for the treatment of bacterial infections.

[0075] Therefore, the N-methylbiphenylpiperidine derivatives of the present invention can effectively reduce the toxicity and drug resistance of Gram-negative bacteria, and can thus be used to prepare drugs for treating diseases caused by Gram-negative bacteria.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The N-methylbiphenylpiperidine derivatives of Formula I, their racemates or optical isomers, their pharmaceutically acceptable salts, solvates or hydrates, characterized in that, The chemical structure of Formula I is shown below: Formula I; Wherein, R is selected from aryl and aryl heterol; The aryl group is selected from one or more of phenyl, benzyl, phenethyl, naphthyl, anthracene, phenanthryl, indene, fluorenyl, and acenaphthene. The aromatic heterol group is selected from one or more of pyrroleyl, imidazolyl, oxazolyl, isoxazolyl, thiophenyl, thiazolyl, pyridyl, pyrazinyl, furanyl, pyridazinyl, morpholinyl, pyrazolyl, indolyl, pyrimidinyl, benzothiazolyl, benzofuranyl, benzimidazolyl, benzoxazolyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, purinyl, carbazolyl, phenothiazinyl, and phenothiazinyl. The above groups may be optionally mono- or poly-substituted by substituents selected from the following: alkyl, alkoxy, fluoroalkyl, halogen, nitro, hydroxy, and cyano.

2. The N-methylbiphenylpiperidine derivative of formula I as described in claim 1, its racemate or optical isomer, its pharmaceutically acceptable salt, solvate or hydrate, characterized in that, R is selected from one of methoxyphenyl, fluorophenyl, trifluoromethylphenyl, methylphenyl, chlorophenyl, hydroxyphenyl, biphenyl, and dimethoxyphenyl.

3. The N-methylbiphenylpiperidine derivative of formula I as described in claim 1, its racemate or optical isomer, its pharmaceutically acceptable salt, solvate or hydrate, characterized in that, The chemical structure of Formula I is selected from any one of the following compounds D1 to D16: 。 4. A method for preparing the N-methylbiphenylpiperidine derivative of Formula I as described in any one of claims 1 to 3, its racemic or optical isomer, its pharmaceutically acceptable salt, solvate, or hydrate, characterized in that, The preparation method includes the following steps: reacting the intermediate shown in Formula 4 with a phenylethylamine derivative via an amide condensation reaction to obtain the product; the chemical structure of Formula 4 is shown below: The phenethylamine derivatives include 3-methoxyphenethylamine, 4-methoxyphenethylamine, 3-fluorophenethylamine, 4-fluorophenethylamine, 4-methylphenethylamine, 4-chlorophenethylamine, o-fluorophenethylamine, 3-chlorophenethylamine, 2-(4-trifluoromethylphenyl)ethylamine, 3-(trifluoromethyl)phenethylamine, o-methoxyphenethylamine, 3-methylphenethylamine, 3-hydroxyphenethylamine, 3,4-dimethoxyphenethylamine, 2-(4-biphenyl)ethylamine, or 2,3-dimethoxyphenethylamine.

5. The preparation method according to claim 4, characterized in that, The synthetic route for preparing the intermediate shown in Equation 4 is as follows: 。 6. A pharmaceutical composition, characterized in that, It comprises an N-methylbiphenylpiperidine derivative of Formula I as described in any one of claims 1 to 3, its racemic or optical isomer, its pharmaceutically acceptable salt, solvate or hydrate, and optionally one or more pharmaceutically acceptable carriers and excipients.

7. The pharmaceutical composition according to claim 6, characterized in that, The pharmaceutical composition also contains at least one antibiotic; Preferably, the antibiotic is selected from at least one of tetracycline, amoxicillin, cefixime, vancomycin, norfloxacin, tobramycin, clarithromycin, and ciprofloxacin.

8. The use of the N-methylbiphenylpiperidine derivative of Formula I as described in any one of claims 1 to 3, its racemic or optical isomer, its pharmaceutically acceptable salt, solvate or hydrate, in the preparation of a medicament as a bacterial quorum sensing modulator; Preferably, the bacteria are Gram-negative or Gram-positive bacteria; more preferably, they are Gram-negative bacteria. More preferably, the Gram-negative bacteria are selected from Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus, Shigella, Brucella, Haemophilus influenzae, Parainfluenza bacteria, Moraxella catarrhalis, Acinetobacter spp., Yersinia spp., Pasteurella spp., Shigella spp., Bordetella pertussis, Bordetella parapertussis, Parahemolyticus, Legionella pneumophila, or Vibrio cholerae.

9. The use of the N-methylbiphenylpiperidine derivative of Formula I as described in any one of claims 1 to 3, its racemic or optical isomer, its pharmaceutically acceptable salt, solvate or hydrate, in the preparation of medicaments for the prevention and / or treatment of diseases caused by bacterial infections; Preferably, the bacteria are Gram-negative or Gram-positive bacteria; more preferably, they are Gram-negative bacteria. More preferably, the Gram-negative bacteria are selected from one or more of the following: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus, Shigella, Brucella, Haemophilus influenzae, Parainfluenza bacteria, Moraxella catarrhalis, Acinetobacter spp., Yersinia spp., Pasteurella spp., Shigella spp., Bordetella pertussis, Bordetella parapertussis, Bacillus parahaemolyticus, Legionella pneumophila, and Vibrio cholerae. Preferably, the diseases caused by bacterial infection include endocarditis, peritonitis, gastroenteritis, cholecystitis, cystitis, diarrhea, empyema, or sepsis.

10. The use of the N-methylbiphenylpiperidine derivatives of Formula I as described in any one of claims 1 to 3, their racemic or optical isomers, their pharmaceutically acceptable salts, solvates or hydrates in the preparation of antibacterial sensitizers; Preferably, the antibacterial sensitizer is used to enhance the sensitivity of bacteria to antibiotics; the antibiotic is selected from at least one of tetracycline, amoxicillin, cefixime, vancomycin, norfloxacin, tobramycin, clarithromycin, and ciprofloxacin; Preferably, the bacteria are Gram-negative or Gram-positive bacteria; more preferably, they are Gram-negative bacteria. More preferably, the Gram-negative bacteria are selected from one or more of the following: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus, Shigella, Brucella, Haemophilus influenzae, Parainfluenza bacteria, Moraxella catarrhalis, Acinetobacter spp., Yersinia spp., Pasteurella spp., Shigella spp., Bordetella pertussis, Bordetella parapertussis, Parahaemolyticus, Legionella pneumophila, and Vibrio cholerae.

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