Ester-based facaplysin derivative, preparation method and application of ester-based facaplysin derivative in antibacterial products

Abstract

The invention discloses a method for rapidly and efficiently preparing a series of novel ester group facaplysin derivatives by combining EDCI and HOBT to react with carboxyl facaplysin and directly carrying out ester exchange reaction on an active ester intermediate and alcohol without separation. The invention also discloses application of the derivatives in resisting methicillin-resistant staphylococcus aureus and escherichia coli. The preparation method comprises the following steps that EDCI and HOBT are combined to activate carboxyl facaplysin for reaction, an activated ester intermediate is generated, the activated ester intermediate and alcohol are directly subjected to esterification reaction without separation, and a series of ester-based facaplysin derivatives are obtained. According to the preparation method, ester-based Fascaplysin derivatives with different structures can be rapidly and efficiently constructed, and compared with a traditional method that ester-based carboline derivatives are firstly synthesized and then high-temperature intramolecular cyclization is performed, the time and the raw material cost are greatly saved, the synthesis efficiency is improved, the reaction process is observable and controllable, and the yield is stable. And the synthesized ester group facaplysin derivative has excellent antibacterial activity on methicillin-resistant staphylococcus aureus and escherichia coli.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical chemical synthesis technology, and particularly relates to an ester-based fascaplysin derivative, its preparation method, and its application in antibacterial products, specifically in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Background Technology

[0002] Fascaplysin is a natural alkaloid isolated from marine sponges, possessing significant antibacterial, antitumor, and anti-Alzheimer's disease bioactivities. However, the extraction of natural fascaplysin is difficult, resulting in low yields, high toxicity, and poor pharmacokinetics, leading to poor drug-like properties. Therefore, chemical modification of the fascaplysin structure is crucial for developing more promising drug candidates.

[0003] Currently, although more than ten synthetic methods for fascaplysin and its derivatives have been publicly reported (MarDrugs, 17 (2019) 496.), the synthetic methods for expanding the fascaplysin compound library are limited. Most synthetic strategies start with different raw materials, proceed through multiple reactions to obtain carboline derivative precursors, and then perform intramolecular cyclization to synthesize fascaplysin derivatives. However, this method is cumbersome, requires harsh reaction conditions, and has unstable yields, making it impossible to rapidly prepare a series of derivatives for bioactivity studies, thus limiting further applied research.

[0004] In existing technologies, there are reports of rapidly constructing structurally diverse carboline derivative precursors via the Suzuki coupling reaction without starting from initial raw materials. These precursors, through intramolecular cyclization, yield fascaplysin derivatives, significantly improving synthetic efficiency (ZL202210017211.0, A Fascaplysin Derivative and Its Preparation Method and Its Application in Anti-MRSA; European Journal of Medicinal Chemistry, 270 (2024) 116347.). These derivatives also exhibit good activity against both Gram-positive and Gram-negative bacteria. Another more convenient method is to directly modify the fascaplysin molecular backbone by introducing functional groups. However, to date, research on the direct derivatization of fascaplysin has been relatively limited.

[0005] In addition, there are reports of specific reactions occurring at the C(9) site in electrophilic aromatic substitution reactions (such as halogenation and sulfonation), thus preparing zwitterions of 9-bromo, 9-chlorofascaplysin, and 9-sulfonic acid fascaplysin. However, this method does not yield nitration products and cannot achieve alkylation or acylation via the classic Friedel-Crafts reaction, which greatly limits the possibility of introducing diverse substituents onto the aromatic ring. For the reaction of fascaplysin with nucleophiles, it was found that the D-ring structure of fascaplysin is unstable and ring-opening under alkaline conditions such as sodium hydroxide, ammonia, or organic amines, leading to structural destruction of fascaplysin. In the reaction with sodium methoxide / methanol, the addition of three molecules of methanol to the pyridinium ring occurs, generating a complex mixture of isomers. This indicates that fascaplysin derivatives are difficult to obtain via this reaction pathway. Organometallic reagents can cause structural destruction of fascaplysin due to addition reactions. These studies reveal that fascaplysin can be derivatized under specific conditions, but also highlight its inherent reactive limitations. These limitations severely hinder the acquisition of structurally diverse Fascaplysin derivatives, thus limiting in-depth exploration of its structure-activity relationship and the discovery of better drug candidates.

[0006] In summary, there is an urgent need in this field to develop a novel, efficient, and universally applicable synthetic method to overcome the shortcomings of existing technologies and to directly introduce diverse functional groups into the Fascaplysin molecular skeleton, thereby providing a solid chemical foundation for the development of next-generation Fascaplysin-like bioactive molecules. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an ester-based fascaplysin derivative, its preparation method, and its application in antibacterial products, specifically its application against MRSA and Escherichia coli. The preparation method of this invention utilizes the combined use of EDCI and HOBT to activate the carboxyl group of fascaplysin through esterification, rapidly and efficiently constructing various ester-based fascaplysin derivatives, significantly improving synthesis efficiency compared to traditional methods.

[0008] The present invention is solved by the following technical solution.

[0009] An ester-based fascaplysin derivative having the following general formula:

[0010] ,

[0011] Wherein, -R is one of methyl, ethyl, propyl, butyl, or pentyl.

[0012] In a preferred embodiment, the propyl group is n-propyl, the butyl group is n-butyl, and the pentyl group is n-pentyl.

[0013] The preparation method of the ester-based fascaplysin derivative of this application includes the following steps: using EDCI and HOBT in combination as activators or additives, esterifying carboxyl-based Fascaplysin with an alcohol to generate an ester-based Fascaplysin derivative; wherein the alcohol is one of methanol, ethanol, propanol, butanol, and pentanol.

[0014] In a preferred embodiment, the molar amount of EDCI is 1.2-1.7 times the molar amount of carboxyl Fascaplysin; the molar amount of HOBT is 1.2-1.7 times the molar amount of carboxyl Fascaplysin.

[0015] In a preferred embodiment, the molar amount of the alcohol is 4-6 times the molar amount of the carboxyl group Fascaplysin.

[0016] In a preferred embodiment, the esterification reaction is carried out in an organic solvent containing an organic amine, preferably a DMF solution.

[0017] In a preferred embodiment, the organic amine is one of triethylamine, tributylamine, ethylenediamine, diethylenetriamine, and pyridine, preferably triethylamine; the molar amount of the organic amine is 1.8-2.2 times the molar amount of carboxyl Fascaplysin.

[0018] In a preferred embodiment, the esterification reaction is carried out at a temperature of 25-50 °C for 3-8 h.

[0019] This application also relates to the application of the ester-based fascaplysin derivative in antibacterial products, specifically: the application of the ester-based fascaplysin derivative in the preparation of products resistant to methicillin-resistant Staphylococcus aureus or Escherichia coli.

[0020] Compared with existing technologies, the present invention has the following advantages: it provides an ester-based Fascaplysin derivative and its preparation method, as well as the application of such derivatives in the fight against MRSA and Escherichia coli. The preparation method of the present invention utilizes the combined use of EDCI and HOBT to activate the carboxyl group of Fascaplysin through esterification, rapidly and efficiently constructing various ester-based Fascaplysin derivatives, significantly improving the synthesis efficiency compared to traditional methods.

[0021] Furthermore, even when using triethylamine organic base, the D ring of Fascaplysin is not destroyed in this invention, and the Fascaplysin derivative is obtained efficiently. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the synthesis of the ester-based Fascaplysin derivative in this invention.

[0023] Figure 2 The image shows the proton NMR spectrum of compound 1, the product of Example 1.

[0024] Figure 3 This is the mass spectrometry characterization of compound 2, the product from Example 2.

[0025] Figure 4 The image shows the proton NMR spectrum of compound 3, the product of Example 3.

[0026] Figure 5 This is the mass spectrometry characterization of product compound 4 from Example 4.

[0027] Figure 6 This is the mass spectrometry characterization of compound 5, the product from Example 5. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0029] In the following embodiments, the same or similar reference numerals denote the same or similar originals or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] An ester-based fascaplysin derivative of this application has the following general formula:

[0031] ,

[0032] Wherein, -R is one of methyl, ethyl, propyl, butyl, and pentyl. Preferably, the propyl is n-propyl, the butyl is n-butyl, and the pentyl is n-pentyl.

[0033] The preparation method of an ester-based fascaplysin derivative according to this application includes the following steps: using EDCI and HOBT in combination as activators or additives, esterifying carboxyl-based fascaplysin with an alcohol to generate an ester-based fascaplysin derivative; wherein the alcohol is one of methanol, ethanol, propanol, butanol, and pentanol; the esterification reaction is carried out in an organic solvent with added organic amine, preferably a DMF solution; wherein the organic amine is one of triethylamine, tributylamine, ethylenediamine, diethylenetriamine, and pyridine, preferably triethylamine.

[0034] The following are specific examples.

[0035] Example 1: Carboxylated Fascaplysin (0.5 mmol), EDCI (0.75 mmol), and HOBT (0.75 mmol) were dissolved in DMF (5 mL), and methanol (2.5 mmol) was added. The mixture was then reacted with Et3N (1.0 mmol) at 30 °C for 4 h. After the reaction was complete, the reaction solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography to obtain the target product, designated as compound 1, with a yield of 50%.

[0036] Example 2: Carboxylated Fascaplysin (0.5 mmol), EDCI (0.85 mmol), and HOBT (0.80 mmol) were dissolved in DMF (5 mL), and ethanol (2.5 mmol) and ethylenediamine (1.0 mmol) were added. The mixture was reacted at 30 °C for 4 h. After the reaction was complete, the reaction solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography to obtain the target product, designated as compound 2, with a yield of 53%.

[0037] Example 3: Carboxylated Fascaplysin (0.5 mmol), EDCI (0.6 mmol), and HOBT (0.6 mmol) were dissolved in DMF (5 mL), and n-propanol (2 mmol) and pyridine (0.9 mmol) were added. The mixture was reacted at 30 °C for 4 h. After the reaction was complete, the reaction solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography to obtain the target product, designated as compound 3, with a yield of 45%.

[0038] Example 4: Carboxylated Fascaplysin (0.5 mmol), EDCI (0.8 mmol), and HOBT (0.85 mmol) were dissolved in DMF (5 mL), and n-butanol (2.5 mmol) and Et3N (1.0 mmol) were added. The mixture was reacted at 30 °C for 4 h. After the reaction was complete, the reaction solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography to obtain the target product, designated as compound 4, with a yield of 55%.

[0039] Example 5: Carboxylated Fascaplysin (0.5 mmol), EDCI (0.75 mmol), and HOBT (0.75 mmol) were dissolved in DMF (5 mL), and n-butanol (3 mmol) and Et3N (1.1 mmol) were added. The mixture was reacted at 30 °C for 4 h. After the reaction was complete, the reaction solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography to obtain the target product, designated as compound 5, with a yield of 52%.

[0040] In Examples 1 to 5 above, the esterification reaction temperature was 25-50 ℃, preferably 40 ℃, and the reaction time was 3-8 h, preferably 6 h. All reactions were completed under inert gas protection by heating and stirring.

[0041] In this application, EDCI: 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide; HOBT: 1-hydroxybenzotriazole; and other raw materials were all commercially available.

[0042] To investigate the bioactivity of the synthesized ester-based Fascaplysin derivatives, antibacterial activity tests were conducted on compounds 1 to 5 against methicillin-resistant Staphylococcus aureus (MRSA ATCC43300) and Escherichia coli (E. coli ATCC25922). The procedures are as follows.

[0043] To conduct minimum inhibitory concentration (MIC) experiments, all compounds were dissolved in DMSO and serially diluted twofold. The highest concentration of the compound added to the 96-well plate was 200 μg / ml. The control group was an equal volume of DMSO. Each concentration was tested in triplicate. After all the compounds were accurately added to the wells, a suspension of methicillin-resistant Staphylococcus aureus (MRSA ATCC43300) and Escherichia coli (E. coli ATCC25922) at a mid-logarithmic concentration of 1×10⁵ CFU / ml was added to the 96-well plate. After the bacterial suspension was added, the 96-well plate was incubated at 37 ℃ for 24 h.

[0044] The results of the minimum inhibitory concentration (MIC) test showed that among the ester-based Fascaplysin derivatives, compound 5 had the best MIC value of 0.195 μg / ml. Compared with the original carboxyl-based Fascaplysin, the newly synthesized ester-based Fascaplysin derivatives showed enhanced antibacterial activity. See Table 1 below for the MIC data of ester-based Fascaplysin derivatives against methicillin-resistant Staphylococcus aureus and Escherichia coli.

[0045] serial number Compound structural formula MRSAATCC43300 E. coliATCC25922 1c 0.39μg / ml 12.5μg / ml 2c 0.39μg / ml 12.5μg / ml 3c 0.39μg / ml 6.25μg / ml 4c 0.39μg / ml 6.25μg / ml 5c 0.195μg / ml 6.25μg / ml Comparative Example 6.25μg / ml >200μg / ml Vancomycin 0.39μg / ml -- Colistin -- 1.56 μg / ml

[0046] Table 1

[0047] It can be seen that the preparation method of ester-based Fascaplysin derivatives provided by this invention is efficient and controllable, and the products have significant antibacterial activity against MRSA ATCC43300 and E. coli ATCC25922, providing important candidate compounds for the development of novel antibacterial products.

[0048] This application also relates to the application of the ester-based fascaplysin derivative in antibacterial products, specifically: the application of the ester-based fascaplysin derivative in the preparation of products resistant to methicillin-resistant Staphylococcus aureus or Escherichia coli, the products of which may be pharmaceuticals, solutions, sprays, coatings, etc.

[0049] As described above, this invention discloses a method for rapidly and efficiently preparing a series of novel ester-based fascaplysin derivatives by reacting carboxyl-based fascaplysin with a combination of EDCI and HOBT, without separating the active ester intermediate, and directly subjecting it to transesterification with an alcohol. The invention also describes the application of these derivatives in combating methicillin-resistant Staphylococcus aureus (MRSA ATCC43300) and Escherichia coli (E. coli BNCC25922). The preparation method includes the following steps: activating the carboxyl-based fascaplysin with a combination of EDCI and HOBT to generate an activated ester intermediate, which is then directly esterified with an alcohol without separation to obtain a series of ester-based fascaplysin derivatives. This invention's method can rapidly and efficiently construct ester-based fascaplysin derivatives with different structures. Compared with traditional methods that first synthesize ester-based carboxyl-based fascaplysin derivatives and then perform intramolecular cyclization at high temperature, it significantly saves time and raw material costs, improves synthesis efficiency, and allows for observable and controllable reaction processes with stable yields. The synthesized ester-based fascaplysin derivatives exhibited excellent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA ATCC43300) and Escherichia coli (E. coli BNCC25922).

[0050] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection of this invention is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. An ester-based fascaplysin derivative, characterized in that, The derivative has the following general formula: Wherein, -R is one of methyl, ethyl, propyl, butyl, or pentyl.

2. The ester-based fascaplysin derivative according to claim 1, characterized in that, The propyl group is n-propyl, the butyl group is n-butyl, and the pentyl group is n-pentyl.

3. The method for preparing the ester-based fascaplysin derivative according to claim 1, characterized in that, Includes the following steps: Using EDCI and HOBT as activators or additives, carboxyl Fascaplysin is esterified with alcohol to generate ester-based Fascaplysin derivatives. The alcohol is one of methanol, ethanol, propanol, butanol, and pentanol.

4. The method for preparing the ester-based fascaplysin derivative according to claim 3, characterized in that, The molar amount of EDCI is 1.2-1.7 times the molar amount of carboxyl Fascaplysin; the molar amount of HOBT is 1.2-1.7 times the molar amount of carboxyl Fascaplysin.

5. The method for preparing the ester-based fascaplysin derivative according to claim 3, characterized in that, The molar amount of the alcohol is 4-6 times the molar amount of the carboxyl group Fascaplysin.

6. The method for preparing the ester-based fascaplysin derivative according to claim 3, characterized in that, The esterification reaction is carried out in an organic solvent with added organic amines.

7. The method for preparing the ester-based fascaplysin derivative according to claim 6, characterized in that, The organic amine is one of triethylamine, tributylamine, ethylenediamine, diethylenetriamine, and pyridine; The molar amount of the organic amine is 1.8-2.2 times the molar amount of carboxyl Fascaplysin.

8. The method for preparing the ester-based fascaplysin derivative according to claim 6, characterized in that, The organic solvent is DMF.

9. The method for preparing the ester-based fascaplysin derivative according to any one of claims 3 to 8, characterized in that, The esterification reaction is carried out at a temperature of 25-50 °C for 3-8 h.

10. The application of the ester-based fascaplysin derivative of claim 1 in antibacterial products, characterized in that, The application of this ester-based fascaplysin derivative in the preparation of products resistant to methicillin-resistant Staphylococcus aureus or Escherichia coli.

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