BODIPY photodynamic antibacterial fluorescent probe with aromatic structure and preparation method of BODIPY photodynamic antibacterial fluorescent probe

Abstract

The invention belongs to the technical field of organic synthesis, and particularly discloses a BODIPY photodynamic antibacterial fluorescent probe with an aromatic structure and a preparation method thereof.The BODIPY photodynamic antibacterial fluorescent probe is characterized in that a BODIPY fluorescent dye and an aldehyde compound are subjected to a novenger condensation reaction, and aryl is introduced to the meso position of BODIPY, so that the two-photon absorption capacity and chemical stability of the compound are enhanced; the introduction of aromatic rings and iodine atoms to a certain extent can have a very good inhibition effect on the proliferation of bacteria, so that not only is the antibacterial effect provided, but also the wound healing can be promoted. Comparison experiments find that the antibacterial effect of the BODIPY with the optimized structure is obviously enhanced, and the BODIPY with non-iodinated aromatic rings introduced to the meso site shows the strongest antibacterial effect. The invention not only provides a design strategy for the development of novel near-infrared photosensitizers, but also has great application potential and research significance in the aspect of photodynamic diagnosis and treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, relates to the synthesis of BODIPY fluorescent probes, and specifically relates to an aromatic structure BODIPY photodynamic antibacterial fluorescent probe and a preparation method thereof. Background Art

[0002] Photodynamic therapy (PDT) is a micro-innovation mode that has emerged in recent years. It is a treatment method involving the dynamic interaction between light source, photosensitizer (Ps) and molecular oxygen. When photosensitizer is activated by light of a specific wavelength, the energy of photon absorbed by the photosensitizer is transferred from the stable ground state to the unstable singlet excited state. Then the singlet excited state photosensitizer undergoes intersystem crossing to generate the triplet excited state. The excited state photosensitizer can react with the surrounding macromolecules through energy transfer or electron transfer to generate reactive oxygen species (ROS). These reactive oxygen species can directly cause bacterial toxicity, thereby leading to bacterial damage and apoptosis. Due to its photophysical properties, such as high photostability, high fluorescence quantum yield, easy modification, and narrow absorption and emission spectrum peaks, boron dipyrrole (BODIPY) is considered to be one of the most versatile fluorophores and is widely used in detection and photodynamic therapy. When BODIPY is used in photodynamic therapy, its antibacterial property is one of the research points. Therefore, the development of a BODIPY fluorescent probe with good antibacterial effect will have an important driving significance for the application of BODIPY. Summary of the invention

[0003] In view of the shortcomings of the prior art, the object of the present invention is to provide an aromatic structure BODIPY photodynamic antibacterial fluorescent probe. The aromatic structure BODIPY photodynamic antibacterial fluorescent probe of the present invention has the advantages of large molar absorption coefficient, high sensitivity and photostability, easy structural modification, obvious antibacterial effect, etc. Another object of the present invention is to provide a method for preparing the fluorescent probe.

[0004] The present invention is achieved through the following technical solutions:

[0005] An aromatic BODIPY photodynamic antibacterial fluorescent probe, the structural formula of which is shown below:

[0006]

[0007] Wherein, R1 is thienyl or p-nitrophenyl, and R2 is H or I.

[0008] A further improvement of the present invention is:

[0009] A method for preparing an aromatic BODIPY photodynamic antibacterial fluorescent probe comprises the following steps:

[0010] Aromatic aldehydes are reacted with 2,4-dimethylpyrrole to produce R-BDP. The reaction equation is as follows:

[0011]

[0012] Wherein, R1 is thienyl or p-nitrophenyl.

[0013] Furthermore, the preparation method further comprises subjecting the compound R-BDP to an iodine reaction to generate R-BDP-II, and the reaction equation is as follows:

[0014]

[0015] Furthermore, the specific process of the cyclization reaction is as follows: after mixing the aromatic aldehyde and 2,4-dimethylpyrrole, dissolving them in freshly distilled dichloromethane at room temperature and heating to reflux, adding dichlorodicyanobenzoquinone and freshly distilled triethylamine TEA in sequence after cooling and stirring, slowly adding boron trifluoride ether BF3·Et2O to the mixed solution under ice bath conditions and continuing to stir, after the reaction is complete, column chromatography, vacuum distillation to remove the solvent, placing a strong acid solution in water to carry out aldehyde group deprotection reaction, drying and purification are carried out to obtain R-BDP.

[0016] Furthermore, the molar ratio of the aromatic aldehyde, 2,4-dimethylpyrrole, dichlorodicyanobenzoquinone, triethylamine and boron trifluoride ether is (0.3-2):(0.4-2.2):(1-4):(0.8-4.4):(1.2-4).

[0017] Furthermore, the specific process of the iodination reaction is: dissolving R-BDP and N-iodosuccinimide in CH2Cl2, and stirring at room temperature for 1h to 8h, and separating and purifying by a chromatographic silica gel column to obtain R-BDP-II.

[0018] Furthermore, the molar ratio of the R-BDP to N-iodosuccinimide is 1:1-4.

[0019] A further improvement of the present invention is:

[0020] The above aromatic structure BODIPY photodynamic antibacterial fluorescent probe is used in the preparation of detection and photodynamic therapy drugs.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Fluoroboron dipyrrole (BODIPY) is considered to be an ideal photosensitive dye due to its high molar extinction coefficient, bright fluorescence, excellent photostability and good biocompatibility. The present invention adopts fluoroboron pyrrole fluorescent dye and aldehyde compound to undergo Knoevenagel condensation reaction, and introduces aromatic groups (such as thiophene, nitrobenzene) at the meso position of BODIPY to enhance the two-photon absorption ability and chemical stability of the compound; by introducing iodine atoms, the singlet-triplet energy gap of the molecule is significantly reduced, and the possibility of non-radiative transition is increased, so that it has good singlet oxygen molecule generation ability and strong light conversion efficiency. To a certain extent, the introduction of aromatic rings and iodine atoms can have a good inhibitory effect on the proliferation of bacteria, not only providing antibacterial effects, but also promoting wound healing. Through comparative experiments, it is found that the antibacterial effect of BODIPY after structural optimization is significantly enhanced, and BODIPY with aromatic rings not iodinated at the meso position exhibits the strongest antibacterial effect. This is of great significance for the research and development of BODIPY-based photodynamic antibacterial fluorescent molecular probes, and has great application potential in photodynamic diagnosis and therapy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the H NMR spectrum of CHS-BDP obtained in Example 1 of the present invention;

[0024] Figure 2 This is the H NMR spectrum of CHS-BDP-II obtained in Example 2 of the present invention;

[0025] Figure 3 This is the H NMR spectrum of CHNO-BDP obtained in Example 3 of the present invention;

[0026] Figure 4 This is the H NMR spectrum of CHNO-BDP-II obtained in Example 4 of the present invention;

[0027] Figure 5 The antibacterial performance of BODIPY modified with different substituents obtained in Example 5 of the present invention against Staphylococcus aureus under in vitro illumination conditions. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific embodiments.

[0029] Example 1: Synthesis of Thienyl BODIPY Fluorescent Probe CHS-BDP

[0030]

[0031] Weigh 254 mg (2.0 mmol) of thiophene-2-carboxaldehyde, inject 418 mg (4.4 mmol) of colorless 2,4-dimethylpyrrole liquid, dissolve in 200 mL of freshly distilled dichloromethane and stir, wait for 10 min, heat and reflux for 1 h, add 454 mg (2 mmol) of 2,3-dimethyl-5,6-dicyanobenzoquinone and 1.2 mL of freshly distilled triethylamine solution after cooling, stir for 1.5 h, slowly add 1 mL of boron trifluoride ether BF3·Et2O to the mixed solution under ice bath conditions and continue stirring for 1 h. After TLC tracking until the raw material reacts completely, column chromatography, vacuum distillation to remove the solvent, place in a strongly acidic solution and add water to carry out aldehyde group deprotection reaction, dry and purify to obtain thiophene-containing BODIPY (CHS-BDP). The compound is detected by nuclear magnetic resonance 1 The target product was confirmed by H NMR spectrum.

[0032] Example 2: Synthesis of iodinated thienyl BODIPY fluorescent probe CHS-BDP-II

[0033]

[0034] Thiophene-containing CHS-BDP was prepared according to the method of Example 1;

[0035] CHS-BDP (330 mg, 1 mmol) and N-iodosuccinimide (450 mg, 2 mmol) were dissolved in dichloromethane (60 mL) and stirred at room temperature for 5 h. CHS-BDP-II (349 mg, 65%) was obtained by silica gel column chromatography (gradient elution: dichloromethane: n-hexane = 1:1). The compound was purified by NMR. 1 The target product was confirmed by HNMR spectrum.

[0036] Example 3: Synthesis of BODIPY fluorescent probe CHNO-BDP containing nitrobenzene

[0037]

[0038] Weigh 332 mg (2.0 mmol) of 4-nitrobenzaldehyde, inject 418 mg (4.4 mmol) of colorless 2,4-dimethylpyrrole liquid, dissolve in 200 mL of freshly distilled dichloromethane and stir, wait for 10 min, heat and reflux for 1 h, add 454 mg (2 mmol) of 2,3-dimethyl-5,6-dicyanobenzoquinone and 1.1 mL of freshly distilled triethylamine solution after cooling, stir for 1.5 h, slowly add 1 mL of boron trifluoride ether BF3·Et2O to the mixed solution under ice bath conditions and continue stirring for 1 h. After TLC tracking until the raw material reacts completely, column chromatography, vacuum distillation to remove the solvent, place in a strong acidic solution and add water to carry out aldehyde deprotection reaction, dry and purify to obtain BODIPY (CHNO-BDP) containing nitrobenzene. The compound is detected by nuclear magnetic resonance 1 The target product was confirmed by H NMR spectrum.

[0039] Example 4: Synthesis of iodinated nitrobenzene-containing BODIPY fluorescent probe CHNO-BDP-II

[0040]

[0041] According to the method of Example 3, CHNO-BDP containing nitrobenzene was prepared;

[0042] Dissolve CHNO-BDP (341 mg, 1 mmol) and N-iodosuccinimide (495 mg, 2.2 mmol) in dichloromethane (60 mL) and stir at room temperature for 5 h. Obtain CHNO-BDP-II (296 mg, 68%) by silica gel column chromatography (gradient elution: dichloromethane: n-hexane = 1:1). The compound was purified by NMR. 1 The target product was confirmed by HNMR spectrum.

[0043] Example 5: Synthesis of BODIPY fluorescent probe MBDP without aromatic group substitution and its iodide MBDP-II

[0044]

[0045] Acetyl chloride and 2,4-dimethylpyrrole were used as raw materials, and the methods of Example 1 and Example 2 were used to synthesize the BODIPY fluorescent probe MBDP without aromatic group substitution and its iodide MBDP-II in sequence.

[0046] Example 6: Anti-Staphylococcus aureus activity experiment of the BODIPY fluorescent probe prepared in Examples 1 to 5 under in vitro illumination conditions:

[0047] Staphylococcus aureus (S. aureus) was cultured in LB broth for 16 h. The incubated bacterial solution was centrifuged at 6000 rpm for 15 minutes to remove the supernatant. The bacterial precipitate was washed three times with PBS and then redispersed in 4 mL of PBS solution. The BODIPY sample (prepared in Examples 1 to 5) with a concentration of 1 mg / mL was prepared to treat the bacteria (10 8 CFU / mL). 8 The bacterial solution with a concentration of 100 CFU / mL was incubated with different BODIPY samples with a concentration of 1 mg / mL, and cultured at 150 rpm for 16 h. A 100 mW fluorescent lamp (λ = 545 nm) with a filter was used to irradiate the light source for 1 h at a distance of 5 cm. Then, samples were taken to test the ultraviolet absorption value of the bacteria at 600 nm, and the bacterial growth curve was drawn. The inhibition rate was calculated at the 12-h time point based on the bacterial growth. Figure 5 The results showed that BODIPY containing aromatic rings without iodine had the best antibacterial effect under the irradiation of 100mW fluorescent lamp (λ=545nm).

[0048] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. An aromatic BODIPY photodynamic antibacterial fluorescent probe, characterized in that: The structural formula is as follows: Wherein, R1 is thienyl or p-nitrophenyl, and R2 is H or I.

2. The method for preparing an aromatic BODIPY photodynamic antibacterial fluorescent probe according to claim 1, characterized in that: The following steps are involved: Aromatic aldehydes are reacted with 2,4-dimethylpyrrole to produce R-BDP. The reaction equation is as follows: Wherein, R1 is thienyl or p-nitrophenyl.

3. The method for preparing an aromatic BODIPY photodynamic antibacterial fluorescent probe according to claim 2, characterized in that: The preparation method further comprises subjecting the compound R-BDP to an iodine reaction to generate R-BDP-II, and the reaction equation is as follows:

4. The method for preparing an aromatic BODIPY photodynamic antibacterial fluorescent probe according to claim 2, characterized in that: The specific process is as follows: after the aromatic aldehyde and 2,4-dimethylpyrrole are mixed, they are dissolved in freshly distilled dichloromethane at room temperature and heated to reflux, and after cooling, dichlorodicyanobenzoquinone and freshly distilled triethylamine TEA are added in sequence and stirred, and the mixed solution is slowly added dropwise with boron trifluoride ether BF3·Et2O under ice bath conditions and continued to be stirred. After the reaction is complete, column chromatography is performed, and the solvent is removed by vacuum distillation, and then water is added to the strongly acidic solution to carry out the deprotection reaction of the aldehyde group, and then drying and purification are carried out to finally obtain R-BDP.

5. The method for preparing an aromatic BODIPY photodynamic antibacterial fluorescent probe according to claim 4, characterized in that: The molar ratio of the aromatic aldehyde, 2,4-dimethylpyrrole, dichlorodicyanobenzoquinone, triethylamine and boron trifluoride ether is (0.3-2):(0.4-2.2):(1-4):(0.8-4.4):(1.2-4).

6. The method for preparing an aromatic BODIPY photodynamic antibacterial fluorescent probe according to claim 3, characterized in that: The specific process is: dissolving R-BDP and N-iodosuccinimide in CH2Cl2, stirring at room temperature for 1 h to 8 h, and separating and purifying by a chromatographic silica gel column to obtain R-BDP-II.

7. The method for preparing a BODIPY photodynamic antibacterial fluorescent probe containing an aromatic structure according to claim 6, characterized in that: The molar ratio of the R-BDP to N-iodosuccinimide is 1:1-4.

8. Use of the aromatic structure BODIPY photodynamic antibacterial fluorescent probe as claimed in claim 1 in the preparation of detection and photodynamic therapy drugs.

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