Sialylphenazine compounds and their application in influenza A virus detection

Abstract

The present invention discloses a sialic acid phenazine compound or a pharmaceutical salt thereof, the structure of which is shown below: wherein R is selected from one of the following groups, and n is a positive integer of 1 to 4; based on the difference in binding between different sialic acid oligosaccharides and human / avian influenza, the sialic acid phenazine compound of the present invention can be used as a probe for specifically distinguishing human influenza and avian influenza in influenza A virus.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of compounds for influenza virus detection, and in particular relates to a sialic acid phenazine compound and application thereof in influenza A virus detection. Background Art

[0002] Influenza is a respiratory disease characterized by seasonal outbreaks, with high morbidity, rapid transmission speed and wide range of transmission. Due to its high virus variability, wide host and diverse transmission routes, it has caused multiple pandemics worldwide, causing great trouble to human health and economic development. Existing influenza detection methods mainly include serological diagnosis after virus culture and separation, virus antigen detection and virus nucleic acid detection, etc., which have the disadvantages of high cost, long time consumption and low sensitivity, making it difficult to achieve rapid detection and risk assessment of viruses from different species and regions. Therefore, developing a rapid and sensitive detection method for influenza virus is an urgent requirement for responding to the current epidemiological analysis and prevention of influenza virus. Summary of the invention

[0003] The first object of the present invention is to provide a sialic acid phenazine compound.

[0004] The second object of the present invention is to provide an application of the sialic acid phenazine compound in the detection of influenza A virus.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of the present invention provides a sialic acid phenazine compound or a pharmaceutically acceptable salt thereof, the structure of which is shown below:

[0007]

[0008] Wherein, R is selected from one of the following groups, and n is a positive integer of 1 to 4;

[0009]

[0010] The structure of the sialic acid phenazine compound is selected from one of the following structures:

[0011]

[0012]

[0013] The second aspect of the present invention provides a use of the sialic acid phenazine compound or a pharmaceutically acceptable salt thereof in the detection of influenza A virus.

[0014] The influenza A virus is selected from H1N1, H7N9 or H3N2.

[0015] The third aspect of the present invention provides a use of the sialic acid phenazine compound or a pharmaceutically acceptable salt thereof in preparing an influenza A virus probe.

[0016] The influenza A virus is selected from H1N1, H7N9 or H3N2.

[0017] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0018] The inventors of the present invention have made extensive and in-depth research and covalently coupled sialic acid oligosaccharides with 9-phenyl-14-phenyl-9,14-dihydrodibenzo[a,c]phenazine compounds by using the efficient oxime reaction of amino and aldehyde groups to prepare a fluorescent probe. It has been found through experiments that a fluorescent compound formula I provided by the present invention exhibits two emission bands under a single excitation wavelength. Among them, compounds formula IIa and IIb can sensitively detect the presence of avian influenza viruses (H5N1, H7N9 and H10N8) through the fluorescence ratio of the dual emission bands, and compounds formula IIc and IId can sensitively detect the presence of human influenza viruses (H1N1 and H3N2) through the fluorescence ratio of the dual emission bands. In the presence of the virus, the sialic acid oligosaccharide part of the compound binds to the head region of HA, and the 9-phenyl-14-phenyl-9,14-dihydrodibenzo[a,c]phenazine part binds to the neck region of HA, resulting in a significant change in the fluorescence ratio of the dual emission bands of the compound. In addition, the compound can be used for the detection and source tracing analysis of different mutant viruses of the same subtype. Therefore, the sialic acid phenazine compound of the present invention can be used as a new type of fluorescent compound for the detection and source tracing of influenza viruses.

[0019] The sialic acid phenazine compound of the present invention has the characteristics of single excitation (365nm) and dual emission (blue: 480nm and red: 600nm). After interacting with the target influenza A virus, the ratio of blue to red light increases significantly (blue light increases, red light decreases), thereby realizing ratiometric fluorescence detection of influenza virus.

[0020] Based on the difference in binding between different sialic acid oligosaccharides and human / avian influenza, the sialic acid phenazine compounds of the present invention can be used as probes for specifically distinguishing between human influenza and avian influenza in influenza A viruses. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the fluorescence spectrum change curve of compounds IIa1 and IIc1 at different human influenza virus H3N2 concentrations, where Figure 1 a in the figure is a schematic diagram of the fluorescence spectrum change curve of IIa1, where Figure 1 Figure b is a schematic diagram of the fluorescence spectrum change curve of IIc1.

[0022] Figure 2Schematic diagram of the fluorescence spectrum change curve of compounds IIa1 and IIc1 at different avian influenza virus H10N8 concentrations, where Figure 2 a in the figure is a schematic diagram of the fluorescence spectrum change curve of IIa1, where Figure 2 Figure b is a schematic diagram of the fluorescence spectrum change curve of IIc1.

[0023] Figure 3 Schematic diagram of the fluorescence spectrum change curve of compounds IIa1 and IIc1 at different avian influenza virus H7N9 concentrations, where Figure 3 a in the figure is a schematic diagram of the fluorescence spectrum change curve of IIa1, where Figure 3 Figure b is a schematic diagram of the fluorescence spectrum change curve of IIc1.

[0024] Figure 4 Fluorescence changes of compounds IIa1 and IIc1 at different concentrations of human and avian influenza viruses (I 480 / I 600 ) Column diagram, where I 480 is the fluorescence value at 480 nm, I 600 is the fluorescence value at 600nm. Figure 4 a and Figure 4 b in the figure are respectively Ia1 and IIc1 in the presence of different human and avian influenza viruses 480 / I 600 Schematic diagram of the column.

[0025] Figure 5 Schematic diagram of confocal fluorescence microscopy showing the response of compound IIa1 to different human and avian influenza viruses.

[0026] Figure 6 Schematic diagram of the selectivity of compound IIc1 against different human and avian influenza viruses. DETAILED DESCRIPTION

[0027] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0028] Example 1

[0029] The synthetic routes of the compounds shown in formula IIa1 and IIc1 are as follows

[0030]

[0031] 1) Preparation of compound IIIb:

[0032] Compound IIIa (1.50 g, 3.33 mmol), 1,4-dibromobutane (0.86 g, 4.00 mmol) and potassium carbonate (2.30 g, 16.65 mmol) were added to 150 mL of acetonitrile and stirred under argon protection for 12 h. The solvent was removed by rotary evaporation, and the crude product was separated by silica gel column (eluent ratio PE / EA was 20:1 to 2:1, v / v) to obtain yellow solid compound IIIb (1.40 g, yield 71.8%). For the synthesis of compound IIIa, see H. Zhou, J. Mei, Y.-A. Chen, C.-L. Chen, W. Chen, Z. Zhang, J. Su, P.-T. Chou, H. Tian. Small, 2016, 12 (47), 6542–6546.

[0033] 1 H NMR (400MHz, CDCl3) δ8.70(d,J=7.5Hz,2H),8.15(d,J=6.9Hz,1H),8.09(d,J=7.5Hz,1H),7.72–7.46(m,6H),7.29(br s,2H),7.10–6.91(m,6H),6.79(t,J=6.0Hz1H),6.58(d,J=7.4Hz,2H),3.80(t,J=5.9Hz ,2H),3.41(t,J=6.6Hz,2H),1.96(dt,J=12.6,6.1Hz,2H),1.81(dt,J=12.0,6.0Hz,2H); 13 C NMR (151MHz, CDCl3) δ154.5,148.5,145.8,143.5,141.7,138.5,136.7,130.1,129.6,129.6,129.3128.8,127.6,127.0,126.7,126. 3,126.2,125.7,125.6,124.7,124.5,124.4,123.0,122.9,121.3,120.6,116.1,114.8,70.0,33.5,29.4,27.9; HRMS(EI)m / z:[M+H] + calcd.for C 36 H 29 BrN2O 584.1463, found 584.1450.

[0034] 2) Preparation of compound IIIc:

[0035] Compound IIIb (305.3 mg, 0.52 mmol), N-hydroxyphthalimide (127.2 mg, 0.78 mmol) and 1,8-diazabicycloundec-7-ene (158.3 mg, 1.04 mmol) were added to 20 mL of anhydrous N,N-dimethylformamide, reacted at 50 °C for 12 h under Ar gas protection, and the solvent was removed by rotary evaporation. The crude product was washed with water and extracted with dichloromethane. The organic phases were combined, dried by rotary evaporation, and directly subjected to the next step of reaction.

[0036] The crude product was dissolved in 20 mL of acetonitrile, and hydrazine hydrate (52.1 mg, 1.04 mmol) was added and stirred at room temperature overnight. Water was added to quench the excess hydrazine hydrate, and the mixture was extracted with dichloromethane. The organic phases were combined after washing with water, and the solvent was removed by rotary evaporation. The crude product was separated by silica gel column (eluent ratio CH2Cl2 / CH3OH was 20:1 to 10:1, v / v) to obtain yellow solid compound IIIc (206.7 mg, yield was 73.9%).

[0037] 1 H NMR(400MHz,DMSO-d6)δ8.97–8.83(m,2H),8.05–7.93(m,2H),7.89–7.78(m,2 H),7.72–7.59(m,3H),7.54(dd,J=11.4,4.2Hz,1H),7.41–7.32(m,2H),7.16–7 .06(m,4H),6.96(d,J=7.9Hz,2H),6.88–6.79(m,1H),6.72–6.62(m,2H),3.77 (t,J=6.4Hz,2H),3.27(t,J=6.9Hz,2H),1.65–1.53(m,2H),1.52–1.44(m,2H); 13 C NMR (151MHz, CDCl3) δ147.7,144.8,138.1,129.9,129.5,128.7,127.3,126.9,126. 5,125.3,124.6,123.0,121.0,116.8,70.4,67.1,30.5,27.7; HRMS(ESI)m / z:[M+H] + calcd.forC 36 H 32 N3O2538.2495, found 538.2490.

[0038] 3) Preparation of compound IIa1:

[0039] Compound IIIc (32.2 mg, 0.06 mmol) and sialic acid oligosaccharide (Neu5Acα2-3Galβ1-4Glc, 26.2 mg, 0.04 mmol) were dissolved in 12 mL MeCN / H2O (2:1, v / v), and acetic acid (0.2 mL, 0.3 mmol) and aniline (0.1 mL, 0.1 mmol) were added and stirred overnight. The solvent was removed by rotary evaporation, and the crude product was separated by C18 column (eluent ratio H2O / MeOH was 4:1, v / v) to obtain yellow solid compound IIa1 (33 mg, yield was 72.0%).

[0040] HRMS(ESI)m / z:[M+K] + calcd.for C 59 H 68 KN4O 20 1190.4064,found 1190.4082.HPLC:t R =5.80min, time is 10min, flow rate is 1.0mL min -1 , the mobile phase was 90% methanol and 10% water with a purity of 97.1%.

[0041] 4) Preparation of compound IIc1:

[0042] Compound IIIc (31.8 mg, 0.06 mmol) and sialic acid oligosaccharide (Neu5Acα2-6Galβ1-4Glc, 26.0 mg, 0.04 mmol) were dissolved in 12 mL MeCN / H2O (2:1, v / v), and acetic acid (0.2 mL, 0.3 mmol) and aniline (0.1 mL, 0.1 mmol) were added and stirred overnight. The solvent was removed by rotary evaporation, and the crude product was separated by C18 column (eluent ratio H2O / MeOH was 4:1, v / v) to obtain yellow solid compound IIa1 (29 mg, yield was 63.0%).

[0043] HRMS(ESI)m / z:[M+K] + calcd.for C 59 H 68 KN4O 20 1190.4064,found 1190.4037.HPLC:t R =5.87min, time is 10min, flow rate is 1.0mL min -1 , the mobile phase was 90% methanol and 10% water with a purity of 96.8%.

[0044] Example 2

[0045] The synthetic routes of the compounds shown in formula IIa2 and IIc2 are as follows

[0046]

[0047] 1) Preparation of compound IIId:

[0048] Compound IIIa (1.25 g, 2.77 mmol), 1,10-dibromodecane (1.01 g, 3.36 mmol) and potassium carbonate (1.91 g, 13.82 mmol) were added to 100 mL of acetonitrile and stirred under argon protection for 6 h. The solvent was removed by rotary evaporation, and the crude product was separated by silica gel column (eluent ratio PE / EA was 20:1 to 2:1, v / v) to obtain yellow solid compound IIId (964.6 mg, yield 52.0%).

[0049] 1 H NMR (400MHz, CDCl3) δ8.71(d,J=8.0Hz,2H),8.15(d,J=7.7Hz,1H),8.09(d,J=7.9Hz,1 H),7.73–7.46(m,6H),7.34–7.26(m,2H),7.12–6.99(m,4H),6.92(dd,J=15.8,5.5Hz,2 H),6.80(t,J=7.0Hz,1H),6.60(d,J=8.5Hz,2H),3.78(t,J=6.4Hz,2H),3.39(t,J=6.9H z,2H),1.83(dt,J=14.2,7.1Hz,2H),1.66(dt,J=14.4,7.2Hz,2H),1.40–1.23(m,12H); 13 C NMR (151MHz, CDCl3) δ159.0,158.7,149.2,149.1,136.3,135.5,134.1,133.2,131.8,131.7,129.5,128.8,128.1,126.7,126.6,126. 4,124.7,124.6,123.7,122.7,120.9,119.6,119.5,70.5,34.7,31.6,29.3,29.0,27.7,26.9,25.3,22.7; HRMS(EI)m / z:[M]calcd.for C 42 H 41 BrN2O 668.2402, found 668.2399.

[0050] 2) Preparation of compound IIIe:

[0051] Compound IIId (788.2 mg, 1.18 mmol), N-hydroxyphthalimide (88.7 mg, 1.77 mmol) and 1,8-diazabicycloundec-7-ene (359.3 mg, 2.36 mmol) were added to 30 mL of anhydrous N,N-dimethylformamide and reacted at 50°C for 12 h under Ar gas protection. The solvent was removed by rotary evaporation, the crude product was washed with water and extracted with dichloromethane, the organic phases were combined, and the reaction was directly carried out in the next step after being dried by rotary evaporation.

[0052] The crude product was dissolved in 20 mL of acetonitrile, and hydrazine hydrate (118.0 mg, 2.36 mmol) was added and stirred at room temperature overnight. Water was added to quench the excess hydrazine hydrate, and the mixture was extracted with dichloromethane. The organic phases were combined after washing with water, and the solvent was removed by rotary evaporation. The crude product was separated by silica gel column (eluent ratio CH2Cl2 / CH3OH was 20:1 to 10:1, v / v) to obtain yellow solid compound IIIc (375.4 mg, yield 51.2%).

[0053] 1 H NMR (400MHz, CDCl3) δ8.71(d,J=7.7Hz,2H),8.15(d,J=7.6Hz,1H),8.09(d,J=7.4Hz,1H),7.74–7.41(m,6H),7.29(br s,2H),7.09–6.98(m,4H),6.98–6.87(m,2H),6.84–6.76(m,1H),6.60(d,J=7.9Hz,2H),3.77(t, J=6.6Hz,2H),3.39(t,J=7.4Hz,2H),1.87–1.81(m,2H),1.69–1.62(m,2H),1.42–1.26(m,12H); 13 C NMR (151MHz, CDCl3) δ146.1,146.1,140.9,135.2,131.2,131.1,130.5,130.2,129.8,129.2,128.6,128.5,127.3,126.6,12 6.5,125.5,124.8,122.8,120.6,119.5,119.5,115.0,72.8,69.6,29.9,28.3,26.0,25.3,25.1,24.3; HRMS(ESI)m / z:[M+H] + calcd.for C 42 H 44 N3O2622.3437, found622.3434.

[0054] 3) Preparation of compound IIa2:

[0055] Compound IIIe (37.0 mg, 0.06 mmol) and sialic acid oligosaccharide (Neu5Acα2-3Galβ1-4Glc, 26.0 mg, 0.04 mmol) were dissolved in 12 mL MeCN / H2O (2:1, v / v), and acetic acid (0.2 mL, 0.3 mmol) and aniline (0.1 mL, 0.1 mmol) were added and stirred overnight. The solvent was removed by rotary evaporation, and the crude product was separated by C18 column (eluent ratio H2O / MeOH was 4:1, v / v) to obtain yellow solid compound IIa1 (30.2 mg, yield was 61.2%).

[0056] HRMS(ESI)m / z:[M+H] + calcd.for C 65 H 81 N4O 20 1237.5444,found 1237.5449.HPLC:t R =6.94min, time is 10min, flow rate is 1.0mL min -1 , the mobile phase was 90% methanol and 10% water with a purity of 96.2%.

[0057] 4) Preparation of compound IIc2:

[0058] Compound IIIe (37.3 mg, 0.06 mmol) and sialic acid oligosaccharide (Neu5Acα2-6Galβ1-4Glc, 26.2 mg, 0.04 mmol) were dissolved in 12 mL MeCN / H2O (2:1, v / v), acetic acid (0.2 mL, 0.3 mmol) and aniline (0.1 mL, 0.1 mmol) were added and stirred overnight. The solvent was removed by rotary evaporation, and the crude product was separated by C18 column (eluent ratio H2O / MeOH was 4:1, v / v) to obtain yellow solid compound IIa1 (28.0 mg, yield was 57.1%).

[0059] HRMS(ESI)m / z:[M+H] + calcd.for C 65 H 81 N4O 20 1237.5444,found 1237.5423.HPLC:t R =7.32min, time is 10min, flow rate is 1.0mL min -1 , the mobile phase was 90% methanol and 10% water with a purity of 98.2%.

[0060] Example 3

[0061] Application of compounds IIa1 and IIc1 prepared in Example 1 in the detection of influenza A virus

[0062] 1 mL PBS buffer (0.01 M, pH 7.40) and 1 μL compound (IIa1 or IIc1, concentration 10 mM) were added to a 1 cm×1 cm×4 cm cuvette to obtain a 10 μM solution. Virus particles (20.48 HAU, 50 μL -1 ), including human influenza virus H3N2, avian influenza virus H7N9 and avian influenza virus H10N8, were fully shaken and allowed to stand for 2 minutes, and the fluorescence spectrum was recorded by a fluorescence spectrometer under 355nm excitation, such as Figure 1 , Figure 2 and Figure 3 As shown, Figure 1 Schematic diagram of the fluorescence spectrum change curve of compounds IIa1 and IIc1 at different human influenza virus H3N2 concentrations, where Figure 1 a in the figure is a schematic diagram of the fluorescence spectrum change curve of IIa1, where Figure 1 Figure b is a schematic diagram of the fluorescence spectrum change curve of IIc1. Figure 2 Schematic diagram of the fluorescence spectrum change curve of compounds IIa1 and IIc1 at different avian influenza virus H10N8 concentrations, where Figure 2 a in the figure is a schematic diagram of the fluorescence spectrum change curve of IIa1, where Figure 2 Figure b is a schematic diagram of the fluorescence spectrum change curve of IIc1. Figure 3 Schematic diagram of the fluorescence spectrum change curve of compounds IIa1 and IIc1 at different avian influenza virus H7N9 concentrations, where Figure 3 a in the figure is a schematic diagram of the fluorescence spectrum change curve of IIa1, where Figure 3 Figure b is a schematic diagram of the fluorescence spectrum change curve of IIc1.

[0063] from Figure 1 , Figure 2 and Figure 3It can be seen that with the increase in virus concentration titer, the red fluorescence of compound IIa1 at 600nm slightly decreased in the presence of avian influenza virus H7N9 and H10N8, while the blue fluorescence at 480nm increased significantly; in the presence of human influenza virus H3N2, the red and blue fluorescence did not change significantly. In the presence of human influenza virus H3N2, the red fluorescence of compound IIc1 at 600nm slightly decreased, while the blue fluorescence at 480nm increased significantly; due to the mutation of the surface hemagglutinin HA of avian influenza virus H7N9, which increased the recognition of α2-6 sialic acid, compound IIc1 also showed a fluorescent response to avian influenza virus H7N9; in the presence of avian influenza H10N8, the red and blue fluorescence did not change significantly. The ratio of blue to red light increased significantly, indicating that human influenza and avian influenza viruses can be distinguished by the ratio of blue to red light.

[0064] The same concentration of human / avian influenza virus, specifically H1N1, H3N2, H5N1, H7N9 and H10N8, was added to the solution of compound IIa1 or IIc1 with a concentration of 10 μM, and the mixture was allowed to stand for 2 minutes after being fully shaken. The fluorescence spectrum was recorded by a fluorescence spectrometer under excitation at 355 nm. The ratio of the fluorescence intensity values ​​at 480 nm and 600 nm (I 480 / I 600 ) draws a bar chart, such as Figure 4 As shown, Figure 4 Fluorescence changes of compounds IIa1 and IIc1 at different concentrations of human and avian influenza viruses (I 480 / I 600 ) Column diagram, where I 480 is the fluorescence value at 480 nm, I 600 is the fluorescence value at 600nm. Figure 4 a and Figure 4 b in the figure are respectively Ia1 and IIc1 in the presence of different human and avian influenza viruses 480 / I 600 Schematic diagram of columns. Compound IIa1 can specifically bind to avian influenza surface hemagglutinin due to its α2-3 sialic acid residues, i.e., avian influenza viruses H5N1 and H10N8 are significantly higher than human influenza H1N1 and H3N2. Compound IIc1 can bind to human influenza surface hemagglutinin due to its α2-6 sialic acid residues, i.e., avian influenza viruses H5N1 and H10N8 are significantly lower than human influenza H1N1 and H3N2. The higher the column, the more obvious the response.

[0065] from Figure 4 It can be seen that compound IIa1 can be expressed by the fluorescence ratio of the dual emission bands (I 480 / I 600) can sensitively detect the presence of avian influenza viruses (H5N1 and H10N8), and compound IIc1 can sensitively detect the presence of human influenza viruses (H1N1 and H3N2) through the fluorescence ratio of the dual emission bands. Since the hemagglutinin HA on the surface of the avian influenza virus H7N9 has a mutation that increases the recognition of α2-6 sialic acid, compounds IIa1 and IIc1 can be used to detect the avian influenza virus H7N9.

[0066] Add the same concentration of human / avian influenza virus, specifically H3N2 and H10N8, to the 10 μM compound IIa1, shake thoroughly and let stand for 2 minutes, then use a pipette to take a small amount and drop it on a glass slide. After the solvent evaporates completely, cover the slide with a cover glass and take a picture using a confocal microscope. The results are shown in Figure 2. Figure 5 As shown, Figure 5 The confocal fluorescence microscopy diagram of compound IIa1's response to different human and avian influenza viruses. In the presence of human influenza virus H3N2, both red and blue light are weak. In the presence of avian influenza virus H10N8, the blue fluorescence of IIa1 is significantly enhanced, while the red fluorescence remains unchanged; the enhanced blue fluorescence indicates that compound IIa1 responds significantly to avian influenza virus H10N8 and has no response to human influenza H3N2, indicating that it can be used to distinguish between avian influenza virus H10N8 and human influenza H3N2.

[0067] Human / avian influenza viruses and proteins, specifically H1N1, H3N2, H7N9, H10N8, H5N1, AdC68 (monkey adenovirus), AdChu7 (human adenovirus), human serum albumin (HSA), bovine serum albumin (BSA), pepsin (PEP), lysozyme (500 μM) and immunoglobulin G (IgG) were added to compound IIc1 at a concentration of 10 μM, and the mixture was allowed to stand for 2 minutes after being fully shaken. The fluorescence spectrum was recorded by a fluorescence spectrometer under excitation at 355 nm, and the fluorescence intensity value ratio (I 480 / I 600 ) draws a bar chart, such as Figure 6 As shown, Figure 6 The results show that compound IIc1 has selectivity against different human and avian influenza viruses. 480 / I 600 The value is significantly higher than that of other proteins, indicating that other proteins have no interference with the detection system.

[0068] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A sialic acid phenazine compound or a pharmaceutically acceptable salt thereof, characterized in that: The structure is as follows: Wherein, R is selected from one of the following groups, and n is a positive integer of 1 to 4; 2. The sialic acid phenazine compound or a pharmaceutically acceptable salt thereof according to claim 1, characterized in that: The structure of the sialic acid phenazine compound is selected from one of the following structures:

3. Use of the sialic acid phenazine compound or a pharmaceutically acceptable salt thereof according to claim 1 or 2 in preparing an influenza A virus probe; in, The influenza A virus is selected from H1N1, H7N9 or H3N2.

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