Use of quinoline chalcone derivatives in the control of plant fungi

Abstract

This invention relates to the field of plant disease control technology, and discloses the use of quinoline chalcone derivatives in the control of plant fungi. In vitro bioactivity tests show that these derivatives exhibit varying degrees of inhibitory activity against a variety of plant fungi, including *Sclerotinia sclerotinia*, *Rhizoctonia solani*, *Botrytis cinerea*, *Fusarium graminearum*, *Fusarium verticillata*, and *Bacillus oryzae*. Compounds KL-T5 and KL-T6 show higher activity against *Botrytis cinerea* than the control drug difenoconazole. The compounds involved in this invention have a simple preparation process, use inexpensive and readily available raw materials, and exhibit excellent activity, making them promising candidates for development as novel agricultural antibacterial agents.

Description

Technical Field

[0001] This invention relates to the field of plant disease control technology, and in particular to the use of a quinoline chalcone derivative in the control of plant fungi. Background Technology

[0002] Fungal diseases seriously threaten crop growth and restrict agricultural development, and are a major cause of frequent plant diseases and crop yield reductions worldwide. Examples include wheat scab, tomato gray mold, rice blast, and Fusarium verticillatum. Currently, the control of plant diseases in agricultural production mainly relies on chemical fungicides with different fungicidal spectra. However, with the long-term and large-scale use of chemical pesticides, fungal resistance is constantly increasing, and problems such as environmental pollution and excessive pesticide residues are becoming increasingly prominent. Therefore, there is an urgent need to develop new pesticides that can effectively control plant diseases while possessing low toxicity and low residue characteristics.

[0003] Quinoline compounds have attracted considerable attention due to their diverse biological effects, including antimalarial, anticancer, and antibacterial activity. The quinoline core is a privileged framework in drug development, valued for its structural diversity, multi-target interactions, favorable pharmacokinetics, and suitability for designing hybrid compounds with antibacterial potential. Flavonols (1,3-diaryl-2-propen-1-one) are a class of α,β-unsaturated ketones and important intermediates in the biosynthesis of flavonoids. They possess broad biological activities, including antibacterial, antifungal, anti-inflammatory, and anticancer properties. Due to their simple structure, readily available synthesis, and extensive chemical modification capabilities, flavonols have become an important framework in drug development. Their conjugated double bonds and aromatic systems enable effective interactions with biological targets. Recent studies have highlighted the strong antibacterial potential of flavonol derivatives, positioning them as potential lead compounds for future antibacterial therapies, demonstrating the pharmacological richness and drug potential of the flavonoid framework in modern medicinal chemistry. Therefore, quinoline-containing chalcone derivatives show great promise, and there are currently no reports of their use in controlling agricultural pathogenic fungi. Summary of the Invention

[0004] To address the above shortcomings, this invention provides a novel application of quinoline chalcone derivatives in combating agricultural pathogenic fungi, enabling their use in controlling diseases caused by various agricultural pathogenic fungi such as *Sclerotinia sclerotinia*, *Rhizoctonia solani*, *Fusarium graminearum*, *Botrytis cinerea*, and *Bacillus thuringiensis*. The specific technical solution is as follows: Use of a quinoline chalcone derivative in the control of plant fungi, wherein the quinoline chalcone derivative is selected from any one of the following: , .

[0005] Preferably, the plant fungus is gray mold. Botrytis cinereaFusarium head blight of wheat Fusarium Graminearum Fusarium verticillata Verticillium Fusarium One or more of them.

[0006] Preferably, the plant fungus is gray mold. Botrytis cinerea .

[0007] Preferably, the plant fungus is *Gray Mold*, the causal agent of tomato rot. Botrytis cinerea .

[0008] The present invention also provides a pesticide composition, characterized in that the active ingredient is a quinoline chalcone derivative, selected from any one of the following: , .

[0009] Preferably, the pesticide composition is one of the following: granules, dry suspension, aqueous suspension, dispersible oil suspension, microcapsule suspension, wettable powder, emulsifiable concentrate, water emulsion, water-dispersible granules, or seed treatment agent.

[0010] Preferably, the pesticide composition further includes adjuvants selected from one or more of dispersants, wetting agents, fillers, emulsifiers, thickeners, dispersion media, disintegrants, preservatives, antifreeze agents, specific gravity regulators, defoamers, oil-phase wall materials, and aqueous-phase wall materials.

[0011] This invention synthesized a series of quinoline-containing chalcone derivatives and tested their activity against plant pathogenic fungi. In vitro activity results showed that these compounds exhibited certain inhibitory activity against agricultural bacteria such as *Fusarium graminearum*, with superior inhibitory effects against *Botrytis cinerea*. Compounds KL-T5 and KL-T6 were significantly superior to the control drug, difenoconazole. Compounds KL-T5 and KL-T6 hold promise for development into novel antifungal drugs against plant pathogenic fungi, particularly *Botrytis cinerea*. This could fill the gap in the market for fungicides and address the current shortage of innovative agricultural drugs.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention discovers that quinoline chalcone derivatives exhibit excellent inhibitory effects against agricultural pathogenic fungi, particularly showing significant inhibitory effects against gray mold, demonstrating excellent in vitro activity.

[0013] 2. The quinoline chalcone derivatives of the present invention have simple structures, are easy to synthesize, and have readily available raw materials, and have the potential to be further developed into novel agricultural fungicides. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 The synthetic route diagrams for the quinoline chalcone derivatives KL-T5 and KL-T6 of this invention are shown. Detailed Implementation

[0016] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in the present invention are commercially available or can be prepared by existing methods.

[0017] Example 1: Synthesis of Quinoline Chalcone Derivatives Synthesis of Intermediate 1: In a round-bottom flask, aniline (1 mmol) and acetic anhydride (1.2 mmol) were dissolved in acetic acid and stirred at 120°C for 2 h. The reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was complete, the reaction solution was poured into ice water, extracted three times with EA, washed once with saturated NaHCO3, and washed once with saturated brine. The organic phase was concentrated to give a white solid intermediate 1 in approximately 85% yield.

[0018] Synthesis of Intermediate 2: Phosphorus oxychloride (24.0 mL, 260 mmol) was added dropwise to DMF (7.20 mL, 93.0 mmol) cooled in an ice bath at 0 °C and stirred for 30 min at 0 °C to form a deep red solution. Acetanilide (Intermediate 1) (5.0 g, 37.0 mmol) was added to the pre-prepared Vilsmeier reagent, and the mixture was stirred at 0 °C for 30 min, followed by heating to 75 °C and maintaining this temperature for 16 h. After cooling the reaction mixture, it was poured into 250 mL of ice water, and the resulting suspension was stirred at 0–5 °C for 30 min. The precipitated solid was collected by filtration, washed with water, and recrystallized from ethyl acetate to give a pale yellow solid, 2-chloro-3-quinoline carbaldehyde, in approximately 80% yield.

[0019] Synthesis of Intermediate 3: In a round-bottom flask, morpholine (1.2 mmol) and potassium carbonate (K₂CO₃, 4.0 mmol) were dissolved in DMF (10 mL). 2-Chloroquinoline-3-carboxaldehyde (Intermediate 2) (1.0 mmol) was added to the mixture with stirring, and the reaction was heated to 80–90 °C and maintained for 6 hours. The reaction progress was monitored by thin-layer chromatography (TLC) using ethyl acetate:n-hexane (8:2) as the mobile phase. After the reaction was complete, the reaction mixture was cooled and poured into ice water. The precipitated solid was collected by filtration, washed thoroughly with water, dried, and recrystallized from ethyl acetate to give compound 3 as a yellow solid.

[0020] Synthesis of KL-T5: To a stirred solution of solid compound 3 (2 mmol), 2',6'-dichloroacetophenone (2 mmol), and ethanol (10 mL), 10% sodium hydroxide aqueous solution (1 mL) was added dropwise. The mixture was stirred for an appropriate time until the reaction was complete. After the reaction was complete (monitored by thin-layer chromatography), the reaction solution was cooled and poured into ice water. The precipitated product was filtered and recrystallized from ethanol. (Reference for synthetic method:) Doi.org / 10.1016 / j.bioorg.2025.109389 ) Synthesis of KL-T6: To a stirred solution of solid compound 3 (2 mmol), 4-nitroacetophenone (2 mmol), and ethanol (10 mL), 10% sodium hydroxide aqueous solution (1 mL) was added dropwise. The mixture was stirred for an appropriate time until the reaction was complete. After the reaction was complete (monitored by thin-layer chromatography), the reaction solution was cooled and poured into ice water. The precipitated product was filtered and recrystallized from ethanol. (Reference for synthetic method:) Doi.org / 10.1016 / j.bioorg.2025.109389 ) The structural characterization parameters of quinoline chalcone derivatives KL-T5 and KL-T6 are shown in Table 1: Table 1. Structural characterization parameters of quinoline chalcone derivatives KL-T5 and KL-T6 Example 2: Determination and Results of Antibacterial Activity of Quinoline Chalcone Derivatives Against Pathogenic Fungi 1. Test reagents: Quinoline chalcone derivatives KL-T5 and KL-T6.

[0021] 2. Test strains: Fusarium graminearum, Botrytis cinerea, Bacillus oryzae, and Fusarium verticillata were all provided by the Gansu Academy of Agricultural Sciences.

[0022] 3. Antibacterial activity test: Test Method: Antibacterial activity was determined using potato dextrose agar (PDA) medium. The preparation method is as follows: Wash and peel potatoes, weigh 200 g, cut into small pieces, and boil until tender (20-30 minutes, until the potato pieces can be pierced with a glass rod). Filter through eight layers of gauze, heat, add 15 g of agar, continue heating and stirring until dissolved, then add glucose, stir well, cool slightly, and add water to 1000 mL. Dispense into Erlenmeyer flasks, stopper and seal, and sterilize at 115℃ for 2 h. Dissolve the test reagents separately in DMSO, add to the medium, mix well, and ensure the compound concentration in the medium is 50 μg / mL. Use an equal concentration of DMSO as a blank control and the marketed drug difenoconazole as a positive control. Pour into plates, cool, inoculate separately, and incubate at 23℃. The inhibition rate of each compound is determined when the mycelium in the blank control completely covers the culture dish. All experiments were conducted in triplicate or in three replicates. The inhibition rate was calculated using the following formula: Antibacterial rate = 100% Table 2. Inhibition rate (%) of quinoline chalcone derivatives against plant pathogenic fungi at 50 μg / mL As shown in Table 2, the quinoline chalcone derivatives prepared in this invention all exhibited varying degrees of inhibitory activity against plant pathogenic fungi. Therefore, further activity tests were conducted on these compounds, and the EC50 values ​​were calculated using SPSS software. 50 The test data for the half-maximal effective concentration (WMC) are shown in Table 3.

[0023] Table 3. EC50 of quinoline chalcone derivatives against plant pathogenic fungi 50 Value (μg / mL) Note: "-" indicates that the antibacterial activity of the compound was not determined.

[0024] As shown in Table 3, the quinoline chalcone derivatives prepared in this invention exhibit excellent inhibitory activity against Botrytis cinerea. The inhibitory activities of compounds KL-T5 and KL-T6 against Botrytis cinerea are 0.280 μg / mL and 0.056 μg / mL, respectively, which are significantly better than the positive control drug difenoconazole.

[0025] As shown in Tables 2 and 3, the quinoline chalcone derivatives prepared in this invention all exhibited varying degrees of in vitro inhibitory activity against plant pathogenic fungi, especially showing excellent inhibitory activity against *Botrytis cinerea*. The inhibitory activity of compounds KL-T5 and KL-T6 against *Botrytis cinerea* was EC 100%. 50The values ​​were 0.280 μg / mL and 0.056 μg / mL, respectively, significantly better than the positive control drug difenoconazole. Therefore, quinoline chalcone derivatives have further research value and are expected to be developed into a novel antifungal drug against plant pathogens, especially against gray mold.

[0026] Example 3: Preparation of 30% KL-T5 Compound Suspension The formulation composition and weight fraction of each raw material are as follows: 30% compound KL-T5, 1.5% alkyl sulfonate ammonium salt condensate (wetting and dispersing agent), 6% polycarboxylate DSC-2006 (wetting and dispersing agent), 4% EO / PO block polyether, 2% ethylene glycol (antifreeze agent), 0.3% xanthan gum (thickener), 0.12% magnesium aluminum silicate (thickener), 0.5% organosilicon (defoamer), and water to 100%.

[0027] Preparation method: The above raw materials are subjected to high-speed shearing in proportion, and then ground in a sand mill for 2-3 hours to obtain 30% compound KL-T5 suspension.

[0028] Example 4: Preparation of 40% KL-T6 Compound Suspension The formulation composition and weight fraction of each raw material are as follows: 40% compound KL-T6, 4% polycarboxylate DSC-2006 (wetting and dispersing agent), 2.7% modified polyacrylate copolymer, 2% sodium dodecyl sulfate, 2% ethylene glycol (antifreeze agent), 0.2% xanthan gum (thickener), 0.2% magnesium aluminum silicate (thickener), 0.5% organosilicon (defoamer), and water to 100%.

[0029] Preparation method: The above raw materials are subjected to high-speed shearing in proportion, and then ground in a sand mill for 2-3 hours to obtain 40% compound KL-T6 suspension.

[0030] Example 5: Preparation of 50% KL-T6 water-dispersible granules The formulation composition and weight fraction of each raw material are as follows: 50% compound KL-T6, 2.6% alkyl naphthalene sulfonate formaldehyde condensate (wetting and dispersing agent), 4% diisopropyl naphthalene sulfonate (wetting and dispersing agent), 1.8% lignin sulfonate (wetting and dispersing agent), 1% corn starch (binder), and kaolin (filler) to make up to 100%.

[0031] Preparation method: The above raw materials are subjected to air jet milling, granulation, drying and sieving to obtain 50% KL-T6 water-dispersible granules.

[0032] Example 6: Preparation of 60% KL-T5 wettable powder The formulation composition and weight fraction of each raw material are as follows: 60% compound KL-T5, 6.7% alkyl naphthalene sulfonate formaldehyde condensate, 3% lignin sulfonate (wetting and dispersing agent), 2% alkyl naphthalene sulfonate (wetting and dispersing agent), 5% silica (filler), and kaolin (filler) to make up to 100%.

[0033] Preparation method: The above raw materials are prepared by air jet pulverization and sieving in proportion to obtain 60% compound KL-T5 wettable powder.

[0034] Example 7: Preparation of 1% Compound KL-T6 Granules The formulation composition and weight fraction of each raw material are as follows: 1% compound KL-T6, 2.6% alkyl naphthalene sulfonate formaldehyde condensate (wetting and dispersing agent), 1.8% lignin sulfonate (wetting and dispersing agent), 20% urea, 4% potassium dihydrogen phosphate, 4% potassium chloride, 1% zinc sulfate, 2% sodium carboxymethyl cellulose (binder), and kaolin to make up to 100%.

[0035] Preparation method: Weigh compound KL-T6, carrier, fertilizer, macro-elements, micro-elements and wetting and dispersing agent, mix them evenly, add binder to knead and granulate, place in 60℃ oven to dry for 8 min, then cool and sieve to obtain 1% compound KL-T6 granules.

[0036] Example 8: Efficacy test of a pesticide for controlling tomato gray mold (1) Test reagents: 30% compound KL-T5 suspension (Example 3); 40% compound KL-T6 suspension (Example 4); 40% difenoconazole suspension (Shaanxi Biaozheng Crop Science Co., Ltd., PD20160699) (2) Experimental design and methods: There were 6 treatments, 3 replicates, and a total of 18 plots. The plots were randomly arranged in a block design and the plot area was 30 m². 2 The dosage is 60 kg of water per acre. The foliar spraying method is used. The first application is carried out before the occurrence of tomato gray mold (March 23). The application is repeated every 7 days for a total of 2 applications. A backpack electric sprayer is used to spray evenly. Plastic film is used to isolate each plot during the application.

[0037] (3) Survey methods The disease incidence was investigated 14 days after the second spraying. Five points were randomly selected from each plot for sampling, and two plants were selected from each point. All leaves of each plant were investigated, and the control effect was calculated based on the disease index according to the tomato gray mold disease grading standard.

[0038] Disease severity is graded according to the following standards (based on leaves): Grade 0: No lesions; Grade 1: 3 lesions on a single leaf; Grade 3: 4-6 lesions on a single leaf; Grade 5: 7-10 lesions on a single leaf; Grade 7: 11-20 lesions on a single leaf, some of which are densely clustered; Grade 9: Dense lesions on a single leaf occupy more than 1 / 4 of the leaf area.

[0039] (4) Calculation method The experimental results are shown in Table 4 below: Table 4 shows the results of field efficacy trials, indicating that the 30% KL-T5 suspension and the 40% KL-T6 suspension achieved 84.19% and 91.7% foliar control efficacy against tomato gray mold, respectively, significantly higher than that of the 40% difenoconazole suspension. These findings not only lead to the development of new agents for the control of tomato gray mold but also have significant practical implications for the chemical control of this disease.

[0040] These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. The use of a quinoline chalcone derivative in the control of plant fungi, characterized in that, The quinoline chalcone derivatives mentioned above are selected from any one of the following: 、 。 2. The use according to claim 1, characterized in that, The plant fungus mentioned is one or more of the following: gray mold, wheat scab, and verticillium.

3. The use according to claim 2, characterized in that, The plant fungus mentioned is *Gray Mold*, the pathogen of tomato rot.

4. A pesticide composition, characterized in that, The active ingredient is a quinoline chalcone derivative, selected from any of the following: 、 。 5. The pesticide composition according to claim 5, characterized in that, The pesticide composition is one of the following: granules, dry suspension, water suspension, dispersible oil suspension, microcapsule suspension, wettable powder, emulsifiable concentrate, water emulsion, water-dispersible granules, or seed treatment agent.

6. The pesticide composition according to claim 5 or 6, characterized in that, The pesticide composition further includes adjuvants selected from one or more of the following: dispersants, wetting agents, fillers, emulsifiers, thickeners, dispersion media, disintegrants, preservatives, antifreeze agents, specific gravity regulators, defoamers, oil-phase wall materials, and aqueous-phase wall materials.

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