Application of a quinoline compound in preventing and treating ralstonia solanacearum

Abstract

The application discloses application of a quinoline compound in preventing and treating Ralstonia solanacearum, and belongs to the technical field of plant bacterial wilt prevention and treatment; the quinoline compound is 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl) quinolin-4(1H)-one; it is found for the first time that 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl) quinolin-4(1H)-one has strong inhibitory activity on Ralstonia solanacearum; experiments show that the MIC of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl) quinolin-4(1H)-one on Ralstonia solanacearum is 5 mu g / mL at 24 h, which is equivalent to that of thiazolidine ketone, and the compound can be used for preventing and treating plant bacterial wilt and provides a new candidate compound for development of a bactericide for Ralstonia solanacearum.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of preventing and treating plant bacterial wilt, and particularly relates to an application of a quinoline compound in preventing and treating Ralstonia solanacearum. BACKGROUND

[0002] R. solanacearum is a soil-borne bacterial pathogen that widely harms solanaceous plants such as tomato, eggplant, pepper, potato, and other plants, and is one of the main pathogenic bacteria of plant bacterial wilt. Ralstonia solanacearum bacterial wilt R. solanacearum can be transmitted through irrigation water, agricultural tools, diseased residues, and soil carrying bacteria, invades plant roots, and rapidly spreads through the vascular system, leading to vascular blockage, causing leaf wilting and plant death. R. solanacearum has strong adaptability and infectivity and rapidly spreads in high-temperature and high-humidity environments, causing great harm to agricultural production.

[0003] Traditional methods for preventing and treating R. solanacearum include using disease-resistant varieties, agricultural measures (such as crop rotation and soil disinfection), and chemical fungicides. However, due to the wide host range and increasing drug resistance of the pathogenic bacteria, the existing chemical fungicides have limited effect. Since quinoline compounds (such as quinine) have been used to treat malaria, quinoline compounds have also been used in the agricultural field to prevent and treat diseases such as rice blast and gray mold, but have not been used to prevent and treat R. solanacearum. SUMMARY

[0004] The first object of the present application is to provide an application of a quinoline compound in preventing and treating R. solanacearum, and the second object is to provide a fungicide for preventing and treating R. solanacearum.

[0005] The first object of the present application is achieved by the application of a quinoline compound in preventing and treating R. solanacearum, wherein the quinoline compound is 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one, and the chemical structural formula is as follows:

[0006] ;

[0007] The MIC of the quinoline compound for R. solanacearum is 5 μg / mL at 24 h.

[0008] The second object of the present application is achieved by the fungicide for preventing and treating R. solanacearum, which uses the 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one as the main active ingredient or one of the active ingredients.

[0009] ​The 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one in the application is from Shanghai Taoshu Biological Technology Co., Ltd., and the 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one is found to have strong inhibitory activity on Ralstonia solanacearum for the first time; tests show that the MIC of the 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one on Ralstonia solanacearum is 5 μg / mL at 24 h, which is equivalent to the MIC (5 μg / mL) of the thiazolidine ketone on Ralstonia solanacearum, and the 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one has strong inhibitory activity on Ralstonia solanacearum, and can be used for plant bacterial wilt prevention and treatment, and provides a new candidate compound for Ralstonia solanacearum fungicide development. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 The chemical structural formula of the 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one in the application is shown in the following figure:

[0011] Figure 2 The calculation results of the antibacterial activity determination of the 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one on Ralstonia solanacearum in the test example are shown in the following table:

[0012] Figure 3 The calculation results of the antibacterial activity determination of the thiazolidine ketone on Ralstonia solanacearum in the test example are shown in the following table: DETAILED DESCRIPTION

[0013] The application will be described in more detail below in combination with test examples and examples, however, the application is not limited thereto, and any transformation or improvement based on the application should be covered within the protection scope of the application.

[0014] The application of the quinoline compound in the prevention and treatment of Ralstonia solanacearum, the quinoline compound is 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one, and the chemical structural formula is as follows: ;

[0015] The MIC of the quinoline compound on Ralstonia solanacearum is 5 μg / mL at 24 h.

[0016] The bactericide for preventing and treating Ralstonia solanacearum is mainly active ingredient or one of active ingredients of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one.

[0017] Further, the effective concentration of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one in the bactericide is ≥ 5 μg / mL.

[0018] Further, the dosage form of the bactericide is aqueous agent, emulsion in water, wettable powder, soluble powder, soluble granule, suspension agent, tablet or effervescent granule.

[0019] Further, the solvent of the aqueous agent or emulsion in water is a fatty alcohol aqueous solution with a mass percentage concentration ≤ 5%.

[0020] Further, the fatty alcohol is methanol, ethanol or propanol.

[0021] The 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one in the application is derived from a drug-like diversity compound library containing 50,000 compounds developed by Shanghai Taoshu Biological Technology Co., Ltd., with a Library ID of F418-0239, a relative molecular mass of 434.47, and a chemical structural formula as Figure 1 .

[0022] The present application carries out the following tests on 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one and thiabendazole.

[0023] Test Example 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one and thiabendazole were detected for their bacteriostatic activity against Ralstonia solanacearum.

[0024] 1. Preparation of test drug solution

[0025] 1-1. Test solution for test group I: Weigh 1.0~3.0 mg of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinoline-4(1H)-one (hereinafter referred to as technical grade) and dissolve it in DMSO. Dilute with water to prepare test solutions with different technical grade concentrations. The technical grade concentrations in each test solution are 10 μg / mL, 30 μg / mL, 50 μg / mL, 100 μg / mL, 300 μg / mL, 500 μg / mL, 1000 μg / mL, and 1500 μg / mL, respectively. The content of DMSO in each test solution is 0.4% (mass fraction).

[0026] 1-2. Test solutions for Group II: Weigh 1.0~3.0 mg of thiabendazole copper (hereinafter referred to as positive control) and dissolve it in DMSO. Dilute with water to prepare test solutions with different positive control concentrations. The positive control concentrations in each test solution are 10 μg / mL, 30 μg / mL, 50 μg / mL, 100 μg / mL, 300 μg / mL, 500 μg / mL, 1000 μg / mL, and 1500 μg / mL, respectively. The content of DMSO in each test solution is 0.4% (mass fraction).

[0027] 2. Preparation of test bacterial suspension

[0028] 2-1. Pick a single colony of Ralstonia solanacearum cultured on NA solid medium and inoculate it into NB liquid medium. Incubate in a constant temperature shaker at 30℃ and 200rpm until the logarithmic growth phase to obtain Ralstonia solanacearum stock solution.

[0029] Formula for NA solid culture medium: 5g peptone, 3g beef extract, 5g sodium chloride, 15g agar, 1L distilled water, pH 7.0;

[0030] The formula for NB liquid culture medium is: 5g peptone, 3g beef extract, 5g sodium chloride, and 1L distilled water.

[0031] 2-2. Dilute the Ralstonia solanacearum stock solution with NB liquid medium to an OD = 0.1 (the Ralstonia solanacearum concentration is approximately 1.5 × 10⁻⁶). 8 The test bacterial solution was obtained by (CFU / mL).

[0032] 3. Test methods

[0033] 3-1. Experimental Group I: Multiple 99 μL test bacterial suspensions were placed in well plates, and 1 μL of the test drug solution of Experimental Group I with different concentrations of the original drug was added to each group. The plates were incubated at 30℃ and 200 rpm for 24 h using a microplate reader to measure the OD. 600The OD values were measured to observe the bacteriostatic effect. At this time, the final concentrations of the positive drug in each well of the plate were 0.1 μg / mL, 0.3 μg / mL, 0.5 μg / mL, 1 μg / mL, 3 μg / mL, 5 μg / mL, 10 μg / mL, and 15 μg / mL, respectively.

[0034] In the test group II, 99 μL of the test bacterial solution was taken and placed in the well plate, 1 μL of the test drug solution of the test group II was added to each group, and the well plate was cultured at 30°C and 200 rpm on a constant temperature shaker for 24 hours. The OD 600 values were measured to observe the bacteriostatic effect. At this time, the final concentrations of the positive drug in each well of the plate were 0.1 μg / mL, 0.3 μg / mL, 0.5 μg / mL, 1 μg / mL, 3 μg / mL, 5 μg / mL, 10 μg / mL, and 15 μg / mL, respectively.

[0035] The minimum concentration at which no Ralstonia solanacearum was observed in the test groups I and II was the minimum inhibitory concentration (MIC) for Ralstonia solanacearum.

[0036] 3-2, Negative control group: 99 μL of the test bacterial solution was taken and placed in the well plate, 1 μL of water containing 0.4% (mass fraction) DMSO was added, and the well plate was cultured at 30°C and 200 rpm on a constant temperature shaker for 24 hours. The OD 600 values were measured.

[0037] 3-3, Blank control group: 99 μL of NB liquid medium was taken and placed in the well plate, 1 μL of water containing 0.4% (mass fraction) DMSO was added, and the OD 600 values were measured.

[0038] 3-4, The entire test was set in triplicate, and the average of the OD 600 values was calculated according to the following formula to calculate the corrected inhibition rate:

[0039] Corrected inhibition rate % = [(OD 600 of the negative control group - OD 600 of the test group) / (OD 600 of the negative control group - OD 600 of the blank control group)] x 100.

[0040] 4, Test results

[0041] The bacteriostatic activities of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one and thiabendazole on Ralstonia solanacearum were shown in Tables 1 and Figure 2 , 2 and Figure 3As shown; the OD of the negative control group was measured. 600 The value was 0.533±0.001, and the OD value of the blank control group was... 600 The value was 0.300±0.002; combined with the OD values ​​of experimental groups I and II in Tables 1 and 2. 600 The corrected inhibition rate (%) corresponding to the concentration of the test drug solution in each experimental group is obtained from the value and the formula for calculating the corrected inhibition rate in Tables 1 and 2.

[0042] Table 1. Antibacterial activity of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinoline-4(1H)-one against Ralstonia solanacearum

[0043]

[0044] Table 2. Results of the antibacterial activity of thiamethoxam against Ralstonia solanacearum.

[0045]

[0046] Combination Figure 3 The MIC of thiamethoxam against Ralstonia solanacearum at 24 h was determined to be 5 μg / mL; Figure 2 The MIC of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinoline-4(1H)-one against Ralstonia solanacearum after 24 h was determined to be 5 μg / mL. This indicates that 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinoline-4(1H)-one exhibits inhibitory activity against Ralstonia solanacearum comparable to that of thiamethoxam, demonstrating strong inhibitory activity against Ralstonia solanacearum and thus suitable for the control of bacterial wilt in plants.

[0047] Example 1: Preparation of a fungicide aqueous solution for controlling Ralstonia solanacearum

[0048] The bactericidal aqueous solution contains 20 μg / mL of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinoline-4(1H)-one in a 4% (mass fraction) methanol aqueous solution. Other components are prepared using conventional methods.

[0049] Example 2: Preparation of a bactericidal aqueous emulsion for controlling Ralstonia solanacearum

[0050] The bactericidal emulsion contains 30 μg / mL of 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinoline-4(1H)-one in a 3% (mass fraction) aqueous ethanol solution. Other components are prepared using conventional methods.

[0051] Example 3 Preparation of bactericidal wettable powder for preventing and treating Ralstonia solanacearum

[0052] The bactericidal wettable powder is prepared according to the conventional method, with the effective concentration of 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one being 40 μg / mL.

[0053] The soluble powder, soluble granules, suspension, tablets and effervescent granules according to the present application are prepared according to the conventional method, with 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one as the active ingredient (effective concentration ≥ 5 μg / mL).

[0054] In addition, the MIC of 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one for Ralstonia solanacearum is 5 μg / mL according to the test example 1, and the bactericidal agent can achieve high-efficiency inhibition (close to 100%) of Ralstonia solanacearum when the effective concentration of 1-ethyl-6-fluoro-7-morpholinyl-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinolin-4(1H)-one in the bactericidal agent is ≥ 5 μg / mL; a large amount of active ingredient is usually selected in the production of the bactericidal agent product, and the bactericidal agent can be applied after being diluted to the appropriate concentration, which is convenient for storage and transportation.

Claims

1. The application of a quinoline compound in the control of Ralstonia solanacearum, characterized in that, The quinoline compound is 1-ethyl-6-fluoro-7-morpholino-3-(3-(p-tolyl)-1,2,4-oxadiazol-5-yl)quinoline-4(1H)-one, and its chemical structural formula is as follows: ； The quinoline compound had a MIC of 5 μg / mL against Ralstonia solanacearum at 24 h.

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