Quinolinone compound, preparation method and application of quinolinone compound in prevention and treatment of plant diseases

Abstract

The invention belongs to the technical field of medicinal chemistry, and particularly relates to quinolinone compounds, a preparation method and application of the quinolinone compounds in prevention and treatment of plant diseases. Compared with the prior art, the quinolinone compound is synthesized and applied to plant disease control, and the technical problem that the bacterial disease treatment effect of a chemical bactericide is reduced due to the fact that the resistance of original bacteria to the bactericide is enhanced in the plant bacterial disease treatment process is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of pharmaceutical chemistry, and specifically relates to a quinolinone compound, a preparation method and application thereof in preventing and controlling plant diseases. Background Art

[0002] Quinolinone compounds have multiple pharmacological effects such as antibacterial, anticancer, anti-tuberculosis, antimalarial, anti-HIV and antibacterial, and they play an important role in the development of new drugs. In recent years, important work has been carried out in the synthesis of new quinolinone derivatives with enhanced activity and their use in the treatment of different bacterial diseases. Quinolinone drugs have the characteristics of high bioavailability, relatively low toxicity and good pharmacokinetics, which have led to the success of clinical trials of quinolinone drugs.

[0003] Plant bacterial diseases are the most difficult to prevent and control during the growth of crops, causing large-scale damage to crops and huge economic losses. Due to the widespread and continuous use of chemical fungicides, plant pathogenic bacteria have become more resistant to fungicides, seriously threatening human health and environmental safety. Therefore, research and development of new pesticides that are efficient, low-toxic, and low-residue and can effectively control plant diseases has become one of the primary goals of current pesticide creation.

[0004] In summary, in order to solve the problem that the resistance of primary bacteria to fungicides is enhanced during the treatment of plant bacterial diseases, resulting in a decrease in the therapeutic effect of chemical fungicides on bacterial diseases, this scheme proposes a quinolinone compound, a preparation method and its application in preventing and controlling plant diseases. Summary of the invention

[0005] The purpose of the present invention is to provide a quinolinone compound, a preparation method and application thereof in preventing and controlling plant diseases, mainly to solve the technical problem that the resistance of primary bacteria to fungicides is enhanced during the treatment of plant bacterial diseases, resulting in a decrease in the therapeutic effect of chemical fungicides on bacterial diseases.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A quinolinone compound, wherein the structural formula of the quinolinone compound is any one of the following:

[0008]

[0009] The present invention also provides a method for preparing quinolinone compounds, comprising the following steps:

[0010] S1: suspend reactant a in anhydrous methanol, then slowly add anhydrous methanol solution of sodium borohydride, and stir to mix and react;

[0011] S2: After the reaction mixture is mixed, p-toluenesulfonic acid monohydrate is added as a catalyst, the reaction is heated, vacuum concentrated, extracted, dried, and purified to obtain a quinolinone compound.

[0012] Preferably, the molar ratio of the reactant a to sodium borohydride is 0.23-0.25:1.

[0013] Preferably, the reactant a is any one of difloxacin hydrochloride, fleroxacin, oxolinic acid, flumequine, moxifloxacin hydrochloride and sparfloxacin.

[0014] The present invention also provides application of the above-mentioned quinolinone compound in preventing and controlling plant bacterial diseases.

[0015] Preferably, the plant bacterial diseases include one or more of rice bacterial blight, citrus canker and bacterial wilt.

[0016] Preferably, the quinolinone compound is compound Ma or Mj.

[0017] The present invention also provides a medicament for preventing and treating bacterial diseases of agricultural plants, wherein the medicament contains the above-mentioned quinolinone compounds; the weight percentage of the quinolinone compounds in the medicament is 1-99%.

[0018] Preferably, the agent further contains an adjuvant or an agriculturally acceptable carrier.

[0019] Preferably, the dosage form of the medicament is a suspension, a wettable powder, a water dispersible granule or an emulsifiable concentrate.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The quinolinone compounds of the present invention have good control effects on plant bacterial diseases, especially showing excellent inhibitory effects on rice bacterial blight, citrus canker and bacterial wilt (see bioassay experiments), and have great application value in treating plant pathogenic bacteria.

[0022] 2) The method for preparing quinolinone compounds in this scheme has high yield and simple synthesis route. Quinolinone compounds are easy to synthesize, simple in structure, green and efficient, etc. They have application value in preventing and controlling agricultural bacterial pathogens and are worthy of further research and development. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The preparation method of the quinolinone compounds of the present invention is shown in Chemical Formula 1:

[0025]

[0026] 1. Compound Synthesis Examples

[0027] Example 1

[0028] Synthesis method of compound Ma

[0029] S1: suspend 31.3 mmol of difloxacin hydrochloride in 450 mL of anhydrous methanol, then slowly add 127 mmol of anhydrous methanol solution of sodium borohydride, wherein the volume of anhydrous methanol is 50 mL, and stir to mix and react;

[0030] S2: After the reaction mixture is mixed, p-toluenesulfonic acid monohydrate is added to the reaction mixture in step S1 as a catalyst, heated at 65 degrees Celsius for 1 hour, then concentrated in vacuo, extracted three times with ethyl acetate and water, dried over anhydrous Na2SO4 and concentrated to obtain the product, and petroleum ether and ethyl acetate in a volume ratio of 1:2 are used as eluents, and the product is purified by silica gel column to obtain the target product Ma.

[0031] Ma: yield: 70%; yellow oil;

[0032] 1 H NMR(400MHz, CDCl3) δ7.46(d,J=13.6Hz,1H),7.18(ddt,J=8.3,5.6,2.8Hz,2H),7.13–7.03(m,2H),5.83(d,J=7.2Hz,1H ),3.75(dd,J=7.5,6.2Hz,2H),2.96(dd,J=6.0,3.9Hz,4H),2.69(dd,J=7.5,6.2Hz,2H),2.45–2.38(m,4H),2.23(s,3H). 13C NMR (101MHz, CDCl3) δ190.87 (d, J = 1.8Hz), 160.16 (d, J = 246.0Hz), 149.27 (d, J = 79.3Hz), 147.28, 145.83 (d, J = 10.0Hz), 141.80 (d, J = 3.0Hz), 127.24 (d,J=8.4Hz),116.54,116.31,113.61,113.39,112.96(d,J=6.0Hz),103.2 3(d,J=2.1Hz),54.38,51.21–48.45(m),45.72,37.62(d,J=1.3Hz).MS-ESI m / z:358.1694[M+H] + .

[0033] Embodiment 2:

[0034] Synthesis method of compound Mc

[0035] The synthesis method of compound Mc is different from that of Example 1 in that difloxacin hydrochloride in Example 1 is replaced by fleroxacin.

[0036] Mc: Yield: 60%; yellow oil;

[0037] 1 H NMR(400MHz, CD2Cl2)δ7.36(dd,J=12.4,1.9Hz,1H),4.73(td,J=4.8,1.4Hz,1H),4.61(td,J=4.8,1.3Hz,1H) ,3.79–3.58(m,4H),3.33(ddd,J=5.9,3.9,1.8Hz,4H),2.67–2.59(m,2H),2.51(t,J=4.9Hz,4H),2.34(s,3H). 13 C NMR (101MHz, CD2Cl2) δ191.49 (dd, J=3.7, 2.0Hz), 150.13 (dd, J=241.4, 6.0Hz), 146.20 (dd, J=242.3, 5.9Hz), 138.44 (dd, J=8.6, 1.8Hz), 134.73 ( dd,J=14.1,12.1Hz),116.14(dd,J=6.8,3.1Hz),109.07,83.37(dd,J=168.4,3.4Hz),55.44,54.15(d,J=9.4Hz),50.80–49.96(m),46.19,36.00.

[0038] MS-ESI m / z:328.1603[M+H]+ .

[0039] Embodiment 3:

[0040] Synthesis method of compound Me

[0041] The synthesis method of compound Me is different from that of Example 1 in that difloxacin hydrochloride in Example 1 is replaced by oxolinic acid.

[0042] Me: Yield: 65%; yellow oil;

[0043] 1 H NMR (400MHz, CH2Cl2) δ7.31(d,J=1.7Hz,1H),6.25(d,J=1.8Hz,1H),5.90(d,J=1.9H z,2H),3.49–3.36(m,4H),2.61(td,J=7.2,1.7Hz,2H),1.17(td,J=7.1,1.8Hz,3H). 13 CNMR(101MHz,CH2Cl2)δ191.75,154.69,150.28,140.04,113.55,106.13,101.55,93.73,48.96,46.47,37.76,10.95.MS-ESI m / z:461.1635[2M+Na] + .

[0044] Embodiment 4:

[0045] Synthesis method of compound Mf

[0046] The synthesis method of compound Mf is different from that of Example 1 in that difloxacin hydrochloride in Example 1 is replaced by flumequine.

[0047] Mf: Yield: 65%; yellow oil;

[0048] 1 H NMR (400MHz, CD2Cl2) δ7.36–7.29(m,1H),6.84(ddt,J=8.5,3.3,1.1Hz,1H),3.58–3.42(m,2H),3.25(ddd,J=12.2,7.1,5.3Hz ,1H),2.87–2.53(m,4H),1.99(dddd,J=13.3,11.8,5.4,4.3Hz,1H),1.84(ddt,J=13.4,5.7,4.0Hz,1H),1.17(d,J=6.6Hz,3H). 13CNMR(101MHz,CD2Cl2)δ193.17(d,J=2.2Hz),154.37(d,J=236.5Hz),145.51,125.95(d,J=6.2Hz),122.15 ,119.28(d,J=5.8Hz),110.48,52.92,47.60,37.97(d,J=1.5Hz),27.50,22.98(d,J=1.5Hz),17.09.MS-ESI m / z:461.1968[2M+Na] + .

[0049] Embodiment 5:

[0050] Synthesis method of compound Mh

[0051] The synthesis method of compound Mh is different from that of Example 1 in that difloxacin hydrochloride in Example 1 is replaced by moxifloxacin hydrochloride.

[0052] Mh: Yield: 45%; yellow oil;

[0053] 1 H NMR (600MHz, CDCl3) δ6.71–6.66(m,1H),3.36–3.26(m,2H),3.11–3.04(m,1H),2.98(dt,J=13.2,5.4Hz,1H),2.87( d,J=1.2Hz,3H),2.82(ddd,J=10.2,7.8,2.3Hz,1H),2.78–2.72(m,2H),2.42(dt,J=12.4,3.9Hz,1H),2.32(tt,J=6. 9,3.7Hz,1H),2.06(ddd,J=12.9,10.5,2.7Hz,1H),1.94(ddd,J=16.7,11.4,5.1Hz,1H),1.82(ddd,J=17.0,5.5,4. 1Hz,1H),1.62(tt,J=8.2,4.2Hz,1H),1.15–1.01(m,2H),0.97–0.84(m,1H),0.68–0.59(m,1H),0.18–-0.02(m,4H). 13C NMR (151MHz, CDCl3) δ192.62 (d, J = 2.4Hz), 148.99 (d, J = 239.3Hz), 144.65, 140.45 (d, J = 6.5Hz), 138.61, 113.87 (d, J = 7.1Hz), 109.88, 6 0.03,58.37,56.69(d,J=2.1Hz),52.77(d,J=7.3Hz),50.01,45.11,38.19,36.81(d,J=2.1Hz),36.09,23.67,22.33,9.44,9.20.MS-ESI m / z:461.1968[2M+Na] + .

[0054] Example 6

[0055] Synthesis method of compound Mj

[0056] The synthesis method of compound Mj is different from that of Example 1 in that difloxacin hydrochloride in Example 1 is replaced by sparfloxacin.

[0057] Mj: Yield: 47%; yellow oil;

[0058] 1 H NMR (400MHz, CDCl3) δ6.27(s,2H),3.47(t,J=6.5Hz,2H),3.31–3.23(m,2H),2.99(dqd,J=9.3,6.2,2.6Hz,2H),2.86(t d,J=6.6,3.0Hz,1H),2.78–2.67(m,2H),2.49(t,J=6.5Hz,2H),1.22(s,1H),1.04(d,J=6.4Hz,6H),0.77–0.63(m,4H). 13 C NMR (101MHz, CDCl3) δ195.20–194.99 (m), 137.72 (dd, J = 20.4, 5.5Hz), 137.21 ( dd,J=12.7,1.6Hz),136.67(dd,J=8.1,2.2Hz),135.43(dd,J=22.7,5.6Hz),13 4.88(dd,J=13.6,9.9Hz),101.99(t,J=2.8Hz),57.31(t,J=4.0Hz),50.02(d,J =193.3Hz),38.83,35.52(d,J=9.1Hz),29.42,19.12,8.96(d,J=7.0Hz).MS-ESI m / z:351.1958[M+H] + .

[0059] II. Bioassay Example: Activity Determination of Quinolinone Compounds against Agricultural Pathogenic Bacteria and Its Results

[0060] 1. Test agents: quinolone derivatives Ma~Mj.

[0061] 2. Test bacteria: Xanthomonas oryzae ACCC 11602, the pathogen of rice bacterial blight, Xanthomonas axonopodis pv.Citri, the pathogen of citrus canker, and Pseudomonas sollamacearum, the pathogen of bacterial wilt, were provided by Gansu Academy of Agricultural Sciences.

[0062] 3. Antimicrobial activity test:

[0063] The strain used in this experiment was frozen at -80℃ in the laboratory with 30% glycerol.

[0064] (1) Take out the frozen strains and streak them on NB solid medium (beef extract: 3 g, peptone: 5 g, yeast powder: 1 g, sucrose: 10 g, agar: 15 g, distilled water: 1 L, pH 7.0; sterilized at 121°C for 20 min), and culture at a constant temperature of 28°C until a single colony grows;

[0065] (2) Pick a single colony from the solid culture medium and place it in NB liquid culture medium (beef extract: 3 g, peptone: 5 g, yeast powder: 1 g, sucrose: 10 g, distilled water: 1 L; sterilized at 121°C for 20 min) and culture on a constant temperature shaker at 28°C and 180 rpm until it reaches the logarithmic growth phase;

[0066] (3) Dilute the strain in the logarithmic growth phase to about 10 6 CFU / mL for future use;

[0067] (4) Dissolve the test compound in an appropriate amount of DMSO to prepare a 20,000 μg / mL solution, add it to the liquid culture medium, mix well, and prepare a drug-containing liquid culture medium with a concentration of 200 μg / mL;

[0068] (5) Take 50 μL of drug-containing culture medium and 50 μL of about 10 6 CFU / mL of bacterial culture was added to the wells of a 96-well plate so that the final compound concentration was 100 μg / mL; 100 μL of the above diluted bacterial solution containing an equal amount of DMSO was used as a control;

[0069] (6) The 96-well plate was incubated in a 28°C constant temperature incubator for 24-48 h until the bacterial solution of the control group grew out, and the OD value (OD600 ), and also measure the OD values ​​of 100 μL of liquid culture medium and a drug at a concentration of 100 μg / mL, and correct the OD values ​​caused by the culture medium and the drug itself.

[0070] The calculation formulas for corrected OD value and inhibition rate are as follows:

[0071] Corrected OD value = OD value of bacterial culture medium - OD value of sterile culture;

[0072] Inhibition rate = (corrected control culture medium bacterial solution OD value - corrected drug-containing culture medium OD value) / corrected control culture medium bacterial solution OD value × 100%

[0073] All experiments were repeated three times, and the inhibition rates of the compounds were shown in Table 1.

[0074] Table 1 Inhibition rate of quinolinone compounds on plant pathogenic bacteria at 100 μg / mL (%)

[0075]

[0076] It can be seen from the test results in Table 1 that the quinolinone compounds involved in the present invention show certain antibacterial activity against rice bacterial blight, citrus canker and bacterial wilt, among which some compounds show high activity, especially compound Ma shows excellent high activity against all three pathogens.

[0077] Two control groups were set up, and the compounds used were chloranil and thiophanate-methyl, respectively. The drug-containing liquid culture medium of the compounds in Examples 1-6 and the compounds in the control group was diluted by two-fold dilution in a 96-well plate to obtain a series of drug-containing culture medium with concentrations of 50, 25, 12.5, 6.25, and 3.12 μg / mL. The corresponding inhibition rates at different concentrations were determined according to the same test method as above. All experiments were repeated three times to determine the MIC of the compounds. 90 The values ​​(the lowest drug concentration that inhibits 90% bacterial growth) are shown in Table 2.

[0078] Table 2 MIC of quinolone derivatives Ma~Mj against plant pathogenic bacteria in vitro 90 (μg / mL)

[0079]

[0080] From the activity test results in Table 2, it can be seen that the quinolinone compounds Ma to Mj prepared by the present invention exhibit different degrees of inhibitory activity against three plant pathogenic bacteria, among which Ma, Me, Mh and Mj have the best activity, and the MIC of 1.377 for Xanthomonas oryzae is 1.237. 90 The value is 6.25~50μg / mL, and the MIC of citrus canker bacteria 90The value is 3.12~50μg / mL, and the MIC of 90 The value is between 1.56 and 100 μg / mL, which is significantly better than the control drugs thiocarbazole and thiophanate-methyl. The raw materials of this type of derivatives are easy to obtain and synthesize, and the antibacterial activity is significantly higher than that of the control drugs thiocarbazole and thiophanate-methyl. This shows that these compounds have the value of further development and are expected to be developed into new agricultural antibacterial agents.

[0081] 3. Pesticide Formulation Preparation Example

[0082] Dosage Form Preparation Example 1: 40% Compound Ma Suspension

[0083] Table 3.1 Preparation components of 40% compound Ma suspension

[0084]

[0085]

[0086] The preparation method is as follows: weigh a wetting agent, a surfactant, a dispersant, an antifreeze agent, a preservative, a defoaming agent, and deionized water according to a ratio, add them into a beaker and mix them evenly, then add the active ingredient into the beaker, and then transfer it to a sand mill, add zirconium oxide beads into the sand mill, grind for 2-3 hours, add thickener xanthan gum and magnesium aluminum silicate and continue grinding for 0.5 hours, control the particle size D95 to be below 5 microns, filter to remove the zirconium oxide beads, and the product can be obtained.

[0087] Dosage Form Preparation Example 2: 20% Compound Ma Dry Suspension

[0088] Table 3.2 Components for preparation of 20% compound Ma dry suspension

[0089] Components content(%) Remark Compound Ma 20 Active ingredients Alkylphenol formaldehyde resin polyoxyethylene ether 5 Wetting Agents Lignin sulfonate 6 Dispersants Glyceryl fatty acid ester polyoxyethylene ether 4 Dispersants Sodium sulfate 2 Disintegrants Polyethylene glycol 2 Binder Dimethicone 0.5 Defoaming agent Kaolin Make up 100 filler

[0090] The preparation method of the dry suspension is as follows: the pesticide active ingredient, wetting agent, dispersant, binder, disintegrant, defoamer, filler and water are mixed, and a slurry is prepared after being evenly mixed by a high-speed shearing machine. The prepared slurry is filtered with a filter gauze. After filtering, the slurry is pumped into a centrifugal spray dryer for drying and granulation, the spray pressure is controlled at 4.5MPa, the inlet air temperature is controlled at 120-150°C, and the outlet air temperature is controlled at 50-75°C. The moisture content of the obtained dry suspension meets the standard requirements. Finally, the dry suspension is sieved by a sieving machine to obtain a sample.

[0091] Dosage Form Preparation Example 3: 60% Compound Ma Wettable Powder

[0092] Table 3.3 Preparation components of 60% compound Ma wettable powder

[0093] Components content(%) Remark Compound Ma 60 Active ingredients Pull open powder BX 6 Wetting Agents Sodium lignin sulfonate 5 First dispersant Polycarboxylates 5 Second dispersant Kaolin Make up 100 filler

[0094] The preparation method is as follows: compound Mb-2, a wetting agent, a dispersant and a filler are weighed according to a ratio, added into a food processor and mixed evenly, and then put into a jet mill to grind.

[0095] Dosage Form Preparation Example 4: 50% Compound Me Water Dispersible Granules

[0096] Table 3.4 Preparation components of 50% compound Me water dispersible granules

[0097] Components content(%) Remark Compound Me 50 Active ingredients Sodium Lauryl Sulfate 4 Wetting Agents Alkylphenol polyoxyethylene ether formaldehyde condensate 2 Dispersants Sodium lignin sulfonate 3 Dispersants Corn starch 2 Disintegrants Polyvinyl alcohol 2 Binder diatomite Make up 100 filler

[0098] The preparation method is as follows: the active ingredient, wetting agent, dispersant, disintegrant, binder and filler are weighed according to the ratio, added into a food processor and mixed evenly, then put into a jet mill for grinding, mixed again with the food processor, added with an appropriate amount of water, and extruded into granules with a granulator to obtain the product.

[0099] Dosage Form Preparation Example 5: 30% Compound Mh Wettable Powder

[0100] Table 3.5 Preparation components of 30% compound Mh wettable powder

[0101] Components content(%) Remark Compound Mh 3 Active ingredients Sodium polycarboxylate 5.2 Wetting Agents Sodium lignin sulfonate 3 First dispersant Benzyl sulfonate formaldehyde condensate 4 Second dispersant Kaolin Make up 100 filler

[0102] The preparation method is as follows: the active ingredient, wetting agent, dispersant and filler are weighed according to the proportion, added into a food processor and mixed evenly, and then put into a jet mill to grind.

[0103] Dosage Form Preparation Example 6: 30% Compound Mj Wettable Powder

[0104] Table 3.6 Components for preparation of 30% compound Mj wettable powder

[0105] Components content(%) Remark Compound Mj 30 Active ingredients Sodium alkyl sulfate 3.6 Wetting Agents Sodium naphthalenesulfonic acid formaldehyde condensate 3 First dispersant Nonionic hydroxylated polyethylene oxide block copolymer 2 Second dispersant diatomite Make up 100 filler

[0106] The preparation process is the same as that of Example 5

[0107] Dosage Form Preparation Example 7: 30% Compound Mc emulsifiable concentrate

[0108] Table 3.7 Components for preparing 30% compound Mc emulsifiable concentrate

[0109]

[0110]

[0111] The preparation method is: weigh the active ingredient, emulsifier and solvent according to the ratio, add them into a container and mix them evenly to obtain a sample. Dosage Form Preparation Example 8: 70% Compound Mf Wettable Powder

[0112] Table 3.8 Components for preparation of 70% compound Mf wettable powder

[0113] Components content(%) Remark Compound Mf 70 Active ingredients Sodium alkyl sulfate 5 Wetting Agents Sodium naphthalenesulfonic acid formaldehyde condensate 1 First dispersant Sodium lignin sulfonate 3 Second dispersant Kaolin Make up 100 filler

[0114] The preparation process is the same as that of Example 5.

[0115] IV. Experiment on the efficacy of drugs for preventing and treating citrus canker:

[0116] Test agents: 40% compound Ma suspension, 20% compound Ma dry suspension, 50% compound Me water dispersible granules, 30% compound Mh wettable powder, 30% compound MC emulsifiable concentrate, 70% compound MF wettable powder;

[0117] Control agent: 20% thiophanate-methyl suspension, registration certificate PD20086024, Zhejiang Longwan Chemical Co., Ltd., commercially available.

[0118] Blank control: clean water

[0119] Test site and citrus varieties: The test site is located in Xiaopingyang, Laibin City, Guangxi, with average soil fertility and a flat terrain. The test variety is Wogan, which is 2 years old and growing well.

[0120] Experimental design and methods: A field efficacy test on Wogan canker was conducted in the Wogan fields in Xiaopingyang, Nanning, Laibin, Guangxi.

[0121] Apply the pesticide during the spring shoot period, focusing on the leaves, and spray evenly on the front and back. A total of 7 treatment plots were set up in the experiment, and each treatment plot was arranged in random blocks. 15 Wogan trees were hung in the plot, and repeated 4 times. Use an Easy Spray Sprayer (capacity 16 kg) for spraying. The dosage of each agent is shown in Table 2-1. A total of 3 sprays were sprayed on March 15, August 25, and September 4, 2024. The days during the application of the pesticide were mostly cloudy or overcast. The blank control group did not receive drug prevention and treatment of ulcer disease.

[0122] Investigation method: Observe and record the occurrence of leaf canker on the 5th and 10th days after each spraying, investigate the prevention effect 10 days after the last spraying, and record relevant data. Use the diagonal sampling method, investigate 5 points at fixed points, investigate 1 citrus tree at each point, sample each tree at 5 points in the east, south, west, north, and center, investigate 1 branch at each point, investigate 12 new leaves on each branch, and record the number of diseased leaves at each level.

[0123] The grade of Wogan canker is divided according to the number of lesions on a single leaf. The grading standards are as follows:

[0124] Level 0: no disease;

[0125] Level 1: 1-5 lesions on each leaf;

[0126] Level 3: 6-10 lesions on each leaf;

[0127] Level 5: 11-15 lesions on each leaf;

[0128] Level 7: 16-20 lesions on each leaf;

[0129] Level 9: There are more than 21 lesions on each leaf.

[0130] The disease index and relative efficacy were calculated according to the following formulas:

[0131] Disease index (%) = [∑ (number of diseased leaves at each level × representative value at each level) / (total number of leaves surveyed × highest representative value)] × 100.

[0132] Relative control effect (%) = (disease index of blank control area after application - disease index of treated area after application) / disease index of blank control area after application × 100.

[0133] Table 4 Results of field efficacy test on the control of citrus canker

[0134] Test drug Dilution multiple Disease index (%) Relative efficacy (%) 40% Compound Ma Suspension 1200 2.30 85.10 50% Compound Me Water Dispersible Granules 1500 4.22 72.60 30% Compound Mh wettable powder 900 4.54 70.56 30% Compound Mj Suspension 900 2.96 80.77 30% Compound Mc WP 900 5.01 67.50 70% Compound Mf Water Dispersible Granules 1200 5.32 65.45 20% Thiophanate-copper suspension 600 5.62 63.53 blank / 15.41 /

[0135] In summary, it can be seen that the relative protective effects of 40% compound Ma suspension and 30% compound Mj suspension are better, both above 80%.

[0136] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A quinolinone compound, characterized in that: The structural formula of the quinolinone compound is any one of the following:

2. A method for preparing a quinolinone compound as claimed in claim 1, characterized in that: The steps include: S1: suspend reactant a in anhydrous methanol, then slowly add anhydrous methanol solution of sodium borohydride, and stir to mix and react; S2: After the reaction mixture is mixed, p-toluenesulfonic acid monohydrate is added as a catalyst, the reaction is heated, vacuum concentrated, extracted, dried, and purified to obtain a quinolinone compound.

3. The method for preparing quinolinone compounds according to claim 2, characterized in that: The molar ratio of the reactant a to sodium borohydride is 0.23-0.25:

1.

4. The method for preparing quinolinone compounds according to claim 2, characterized in that: The reactant a is any one of difloxacin hydrochloride, fleroxacin, oxolinic acid, flumequine, moxifloxacin hydrochloride and sparfloxacin.

5. Use of the quinolinone compound as claimed in claim 1 in the prevention and treatment of plant bacterial diseases.

6. The use of a quinolinone compound in the prevention and treatment of plant bacterial diseases according to claim 5, characterized in that: The plant bacterial diseases include one or more of rice bacterial blight, citrus canker and bacterial wilt.

7. The use of a quinolinone compound in the prevention and treatment of plant bacterial diseases according to claim 5, characterized in that: The quinolinone compound is compound Ma or Mj.

8. A medicament for preventing and treating bacterial diseases of agricultural plants, characterized in that: The medicament contains the quinolinone compound as claimed in claim 1; the weight percentage of the quinolinone compound in the medicament is 1% to 99%.

9. The agent for preventing and controlling bacterial diseases of agricultural plants according to claim 8, characterized in that: The medicament contains an adjuvant or an agriculturally acceptable carrier.

10. The agent for preventing and controlling bacterial diseases of agricultural plants according to claim 8, characterized in that: The dosage form of the medicament is suspension, wettable powder, water dispersible granule or emulsifiable concentrate.

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