Uses of medical compounds with amidine skeletons in combating plant pathogenic bacteria

Abstract

This invention belongs to the field of medicinal chemistry and discloses the use of a class of medicinal compounds with anamidinic skeletons in the prevention and control of plant bacterial diseases caused by *Xanthomonas oryzae* ACCC 11602 (the pathogen of rice bacterial blight), *Xanthomonas axonopodis* pv. Citri (the pathogen of citrus canker), and *Pectobacterium atroseptica* ACCC 19901 (the pathogen of potato black shank). These compounds are readily available, low in cost, and have a broad fungicidal spectrum, making them worthy of further research and development.

Description

Technical Field

[0001] This invention belongs to the field of medicinal chemistry and discloses the use of medicinal compounds with an amidine skeleton in the prevention and treatment of bacterial diseases in plants. Background Technology

[0002] Currently, plant pathogenic bacteria infections occur worldwide, with diseases caused by pathogens such as rice bacterial blight, citrus canker, and potato black shank being particularly severe. These pathogens cause significant damage to food crops, leading to a substantial decline in the quality and yield of agricultural products. Consequently, the income of agricultural workers is also reduced. Therefore, there is an urgent need to actively explore fungicides with a broad spectrum of activity and novel targets to combat plant pathogenic bacterial infections.

[0003] Compounds with an amidine skeleton are key structural units of bioactive molecules commonly used in agriculture and the chemical industry. Meanwhile, amidine, as an important nitrogen-containing group, also has wide applications in medicine. The compound described in this invention exhibits significant antibacterial activity against rice bacterial blight pathogens, citrus canker pathogens, and potato black shank pathogens, demonstrating the potential and advantage of repurposing existing drugs. It can be further developed into a novel agricultural chemical fungicide. Summary of the Invention

[0004] The purpose of this invention is to provide the use of medical compounds with an amidon skeleton in their agricultural antibacterial applications for the prevention and control of plant diseases caused by rice bacterial blight pathogens, citrus canker pathogens, and potato black shank pathogens.

[0005] To achieve the above objectives, the present invention provides the following technical method:

[0006] This invention provides a medicinal compound with an amidine skeleton that exhibits inhibitory effects against *Xanthomonas oryzae* ACCC 11602 (the pathogen causing bacterial blight of rice), *Xanthomonas axonopodis* pv. Citri (the pathogen causing citrus canker), and *Pectobacterium atroseptica* ACCC 19901 (the pathogen causing black shank of potato), and has the following advantages:

[0007] 1) The medical compounds with an amidine skeleton involved in this invention exhibit excellent antibacterial activity against agricultural pathogens, especially against the pathogen of citrus canker. Among them, compound 8 has an MIC of 0.78 μg / mL against the pathogen of citrus canker.

[0008] 2) Medical compounds with anamidinium skeletons exhibit high activity, broad spectrum, and readily available raw materials against plant pathogenic bacteria, and have the potential to be further developed into novel agricultural antibacterial agents. Detailed Implementation

[0009] To better understand the present invention, the following specific embodiments further illustrate the above-described content of the present invention. However, this should not be construed as a limitation of the present invention. Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods.

[0010] Example 1: Compounds 1-8 were commercially available, with the following CAS numbers and purities: (1) Chlorpheniramine hydrochloride, CAS: 25875-51-8, purity: 98%; (2) Polyhexamethylene biguanide, CAS: 27083-27-8, purity: 98%; (3) Chlorhexidine acetate, CAS: 206986-79-0, purity: 98%; (4) Imidazole benzoyl dipropionate, CAS: 55750-06-6, Purity: 95%; (5) Diacetamide triazine, CAS: 908-54-3, Purity: 99%; (6) Triazine, CAS: 536-71-0, Purity: 99%; (7) Pentamidine, CAS: 100-33-4, Purity: 98%; (8) Phenformin hydrochloride, CAS: 834-28-6, Purity: 97%.

[0011] Example 2: A medicinal compound with an amidine skeleton, the structural formula of which is as follows:

[0012]

[0013] Example 3: Determination of the antibacterial activity of medical compounds with an amidine skeleton against plant pathogenic bacteria

[0014] The bacterial strains used in this experiment were cryopreserved in the laboratory at -80℃ with 30% glycerol. The cryopreserved strains were removed and streaked onto NB solid medium for agricultural bacteria (beef extract: 3g, peptone: 5g, yeast extract: 1g, sucrose: 10g, agar: 15g, distilled water: 1L, pH 7.0; sterilized at 121℃ for 20min), and incubated at 28℃ until single colonies appeared. Single colonies from the solid medium were then transferred to NB liquid medium for agricultural bacteria (beef extract: 3g, peptone: 5g, yeast extract: 1g, sucrose: 10g, distilled water: 1L; sterilized at 121℃ for 20min) and incubated at 28℃ with shaking at 180 rpm until the logarithmic growth phase. The strains in the logarithmic growth phase were then diluted with the appropriate liquid medium to approximately 10... 6 CFU / mL is prepared for use. Dissolve the compounds separately in DMSO, add them to the liquid culture medium, mix thoroughly, and prepare a drug-containing liquid culture medium with a concentration of 200 μg / mL. Take 50 μL of the drug-containing culture medium and the same volume of approximately 10... 6CFU / mL bacterial culture was added to the wells of a 96-well plate, resulting in a final drug concentration of 100 μg / mL. A control of 100 μL of bacterial culture containing an equal amount of DMSO was used. The 96-well plates were incubated at 28°C for 24–48 h until bacterial growth was observed in the control group. The OD value (OD) of the bacterial culture in each well was then measured using a microplate reader. 600 In addition, the OD values ​​of 100 μL of liquid culture medium and a 100 μg / mL drug concentration were measured to correct for the OD values ​​caused by the culture medium and the drug itself. The formulas for calculating the corrected OD value and inhibition rate are as follows:

[0015] Corrected OD value = OD value of bacterial culture medium - OD value of sterile culture medium;

[0016] Inhibition rate = (OD value of bacterial suspension in control medium after correction - OD value of bacterial suspension in drug-containing medium after correction) / OD value of bacterial suspension in control medium after correction × 100%. All experiments were conducted in triplicate, and the inhibition rates of the compounds were measured and are shown in Table 1.

[0017] Table 1. Antibacterial activity of medicinal compounds with an amidine skeleton at 100 μg / mL

[0018]

[0019] Note: " / " indicates that the compound is inactive against this bacterial strain.

[0020] As shown in Table 1, the medical compounds with an amidine skeleton involved in this invention all exhibited certain antibacterial activity against the tested strains. Among them, compounds 2, 7, and 8 showed an inhibition rate of 100% against the three tested strains at 100 μg / mL.

[0021] Example 4: Determination of the minimum inhibitory concentration (MIC) of medical compounds with an amidine skeleton

[0022] The drug-containing liquid culture medium was diluted in 96-well plates using a two-fold dilution method to obtain a series of 50 μL drug-containing media of various concentrations. The inhibition rates corresponding to these concentrations were then determined according to the same experimental method described in Example 2. The lowest concentration with an inhibition rate greater than 90% was defined as the MIC. The obtained activity data are shown in Table 2.

[0023] Table 2. MIC values ​​of compounds

[0024]

[0025]

[0026] Note: " / " indicates that the MIC value of the compound is greater than 100 μg / mL.

[0027] As shown in Table 2, some medicinal compounds with an amidine skeletons exhibited good antibacterial activity against the tested strains. Among them, compound 8 showed the strongest inhibitory effect, with the lowest MIC value against the citrus canker pathogen reaching 0.78 μg / mL.

[0028] In summary, the medical compounds with an amidine skeleton described in this invention all exhibit certain inhibitory effects on plant pathogenic bacteria, and the antibacterial activity of some compounds is higher than that of the commercially available positive control drug thiabendazole copper, which has value for further research and development.

Claims

1. The application of chlorhexidine acetate in the treatment of plant pathogenic bacteria, wherein the molecular structure of chlorhexidine acetate is characterized as follows: Its characteristics are, The use of chlorhexidine acetate in the prevention and control of rice bacterial blight, citrus canker, and potato black shank.

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