Novel macrolide derivative and synthetic method thereof

Abstract

The invention relates to a novel macrolide derivative, which is characterized in that the novel macrolide derivative belongs to the technical field of drug design and synthesis, the compound provided by the invention takes tilmicosin as a mother nucleus, a 9-position carbonyl group which is easy to generate internal ketalation under an acidic condition is used for modification, a hydrazide group and the 9-position carbonyl group are used for nucleophilic addition, and the novel macrolide derivative is obtained. The acylhydrazone group with excellent antibacterial activity is generated, so that compared with tilmicosin, a novel medicine which is wider in antibacterial spectrum, more stable under an acidic condition and higher in bioavailability is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of drug design and synthesis, and specifically relates to a novel macrolide antibiotic derivative and a synthesis method thereof. Background Art

[0002] Macrolide antibiotics can be divided into 14-, 15-, and 16-membered macrolides according to the number of carbon atoms in the ring. It is a type of macrolide produced by streptomycin that contains a weak base group outside the macrocyclic ring or a type of derivative modified from it. This type of antibiotic not only has the characteristics of a broad antibacterial spectrum, but also has been found through long-term clinical trials and production applications to have few allergies and side effects of β-lactam, aminoglycoside and polypeptide antibiotics. Macrolide antibiotics can inhibit bacterial protein synthesis to varying degrees. They act at the entrance of the central peptide release channel of bacterial peptidyl transferase and bind to the V domain of the 23S rRNA of the 50S subunit of the ribosome, blocking the peptide release channel and thus blocking the translocation of peptidyl tRNA, inhibiting bacterial protein synthesis at the ribosome level.

[0003] Although the currently available tilmicosin has good antibacterial effect, it is prone to dehydration cyclization under acidic conditions to generate hemiketal derivatives, which reduces the antibacterial effect. Summary of the invention

[0004] The present invention selects the macrolide drug tilmicosin with excellent antibacterial activity, and aims to make the candidate compound inhibit bacterial protein synthesis by binding to RNA, thereby achieving the antibacterial purpose.

[0005] The technical solution specifically adopted in the present invention is: A novel macrolide derivative, characterized in that the chemical formula of the derivative is: .

[0006] Wherein, the R is one of the following structural formulas: .

[0007] The present invention changes the 9-position carbonyl group which is easy to undergo hemiketalization into a hydrazide group with excellent antibacterial activity, so as to achieve the purpose of being stable in acidic conditions and having a better antibacterial effect.

[0008] The compound of the present invention uses tilmicosin as a parent core, is modified around the 9-position carbonyl group that is prone to undergo ketalization under acidic conditions, and uses a hydrazide group to perform nucleophilic addition with the 9-position carbonyl group to generate an acylhydrazone group with excellent antibacterial activity, thereby obtaining a new drug that has a broader antibacterial spectrum than tilmicosin, is more stable under acidic conditions, and has higher bioavailability.

[0009] Finally, ultraviolet-visible absorption spectroscopy, in vitro antibacterial experiments and other experiments also verified that it has a killing effect on bacteria. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the UV-visible spectrum of compound 2; Figure 2 This is the UV-visible spectrum of compound 3. DETAILED DESCRIPTION

[0011] Example 1

[0012] 1. Synthesis (1) Weigh tilmicosin (1.0 g, 0.001 mol) and isoniazid (0.24 g, 0.0015 mol, 1.5 eq) and dissolve them in 15 mL of methanol. Add 1 mL of glacial acetic acid and heat under reflux for 36 h. After the reaction is completed, spin dry the solvent, add water and adjust the pH to 10 with NaOH solution. At this time, a solid precipitates. Extract with ethyl acetate three times, combine the organic phases, wash with saturated brine, dry the organic phase with anhydrous magnesium sulfate, and remove the organic layer solvent in vacuo to obtain a yellow amorphous solid.

[0013] (2) Weigh tilmicosin (1.0 g, 0.001 mol) and nicotinic acid hydrazide (0.24 g, 0.0015 mol, 1.5 eq) and dissolve them in 15 mL of methanol. Add 1 mL of glacial acetic acid and heat under reflux for 36 h. After the reaction is completed, spin dry the solvent, add water and adjust the pH to 10 with NaOH solution. At this time, a solid precipitates. Extract with ethyl acetate three times, combine the organic phases, wash with saturated brine, dry the organic phase with anhydrous magnesium sulfate, and remove the organic layer solvent in vacuo to obtain a yellow amorphous solid.

[0014] (3) Weigh tilmicosin (1.0 g, 0.001 mol) and 3-hydroxy-2-naphthoic acid hydrazine (0.34 g, 0.0015 mol, 1.5 eq) and dissolve them in 15 mL of methanol. Add 1 mL of glacial acetic acid and heat under reflux for 36 h. After the reaction is completed, spin dry the solvent, add water and adjust the pH to 10 with NaOH solution. At this time, a solid precipitates. Extract with ethyl acetate three times, combine the organic phases, wash with saturated brine, dry the organic phase with anhydrous magnesium sulfate, and remove the organic layer solvent in vacuo to obtain a yellow amorphous solid.

[0015] (4) Tilmicosin (1.0 g, 0.001 mol) and aminourea (0.13 g, 0.0015 mol, 1.5 eq) were weighed and dissolved in 15 mL of methanol. 1 mL of glacial acetic acid was added and heated to reflux for 36 h. After the reaction was completed, the solvent was dried, water was added and the pH was adjusted to 10 with NaOH solution. At this time, a solid was precipitated. It was extracted three times with ethyl acetate, the organic phases were combined, washed with saturated brine, and the organic phase was dried with anhydrous magnesium sulfate. The organic layer solvent was removed in vacuo to obtain a white amorphous solid.

[0016] Example 2: In vitro antibacterial experiment The minimum inhibitory concentration (MIC, μg / mL) is defined as the lowest concentration (highest dilution) of each compound that completely inhibits bacterial growth after 18-24h of incubation at 37°C using the standard two-fold serial dilution method in a 96-well microplate according to the CLSI method. Tilmicosin, tylosin, and erythromycin were used as control drugs. The bacterial suspension was adjusted to a concentration of 1×10 5 CFU. First, the compound was dissolved in DMSO to prepare the stock solution, and then the test compound and control drug were diluted in broth to obtain the required concentration. These dilutions were inoculated with bacterial solution at 37°C and incubated at 37°C for 16-24 hours. The absorbance was detected with an ELISA reader, and the experiment was repeated three times to prevent errors. The in vitro antibacterial results are shown in the table: .

[0017] Compounds 2 and 3 with the best in vitro antibacterial effects were screened out for UV-visible spectroscopy experiments.

[0018] 3. UV-Visible Spectroscopy UV-visible spectroscopy was used to study the spectral characteristics of the structural changes of the drug and ctDNA complex, and the UV-visible absorption of the drug was detected in the presence and absence of ctDNA. The drug was prepared into a drug solution of a certain concentration using Tris-HCl solution and dimethyl sulfoxide, and UV-visible absorption was performed. ctDNA (50μL-400μL) was added, and each time ctDNA was added, it was incubated at 37°C in a water bath for 5 minutes, and then taken out and left to stand for one minute before testing.

[0019] Based on the molecular docking results, compound 2 and compound 3 mainly interact with DNA in an embedded manner, and the UV-visible absorption spectrum is used to verify the action mode of compound 2 and compound 3 with DNA. When the drug small molecule is embedded in the DNA structure, its π* orbital can couple with the π orbital of the DNA base pair, thereby reducing the π→π* transition energy level and the maximum absorption wavelength of the UV-visible absorption spectrum will be red-shifted. On the other hand, the coupled π orbital part will be filled with electrons, thereby reducing the transition probability and producing a hypochromic effect. As shown in the figure, as the concentration of ctDNA increases, the maximum absorption peak of the drug small molecule gradually decreases. According to The calculated color reduction rates of compound 2 and compound 3 are 13.06% and 10.01%, respectively.

Claims

1. A novel macrolide derivative, characterized in that: The chemical formula of the derivative is: 。 2. The novel macrolide derivative according to claim 1, characterized in that: The R is one of the following structural formulas: 。

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