A thioether-containing pleuromutilin derivative, and a preparation method and use thereof

Abstract

The application relates to a thioether-containing pleuromutilin derivative, a preparation method and application thereof; the structural formula is shown in formula H; through antibacterial activity test on the thioether-containing pleuromutilin derivative, it is proved that the thioether-containing pleuromutilin derivative has good antibacterial activity on rice bacterial leaf blight, rice bacterial disease and citrus canker bacteria. The thioether-containing pleuromutilin derivative can be applied to preparation of a rice bacterial disease prevention and control agent, and the preparation method is simple, and the production cost is low.

Description

Technical Field

[0001] This application relates to the field of pesticide technology, specifically to a thioether-containing truncated pleurotin derivative, its preparation method, and its uses. Background Technology

[0002] Plant diseases are one of the major biological stressors threatening global food security, with diseases caused by pathogenic bacteria being particularly challenging. Unlike fungal diseases, bacterial pathogens reside within the vascular bundles or tissues of plants, and their spread primarily occurs through rain splash, irrigation water, insects, and agricultural operations. Once an outbreak occurs, it spreads rapidly, with rice bacterial blight being particularly severe. Rice bacterial blight is caused by pathogenic species of the genus Xanthomonas. Xanthomonas oryzae pv. Oryzae This disease is a devastating bacterial disease. Listed as a Class A crop disease in my country, it primarily attacks the vascular system of rice, causing leaf withering and loss of function, severely hindering photosynthesis and affecting grain filling. Affected fields typically experience yield reductions of 10%-30%, but in severe cases, losses can exceed 50%, or even total crop failure. Statistics show that this disease causes billions of dollars in rice losses annually in Asia, directly threatening the food security of hundreds of millions of people. Rice bacterial blight also occurs in Asia, Africa, Australia, and the Americas, but in China it is mainly concentrated in rice-growing areas such as East China, Central China, and South China. Currently, with warmer weather, its range and risk of spread are expanding. Currently, the main control method for bacterial diseases relies on chemical methods, heavily depending on traditional agents such as antibiotics and copper-based fungicides. However, long-term and widespread use has led to increasingly serious problems: First, as mentioned earlier, conventional broad-spectrum fungicides are ineffective against bacteria. The overuse of agricultural antibiotics (such as streptomycin sulfate, which has been banned) has led to a sharp increase in antibiotic resistance in pathogens, significantly reducing their efficacy. Secondly, residues of chemical pesticides in the environment pollute soil and water sources, kill beneficial organisms and natural enemies such as bees and dragonflies, and disrupt the ecological balance of farmland. Pesticides entering water bodies through runoff can also harm aquatic ecosystems. Furthermore, pesticide residues in rice directly affect consumer health. Excessive or inappropriate use of pesticides can lead to pesticide contamination in rice products, raising public concerns about food safety. Therefore, facing multiple challenges such as prominent pesticide resistance, poor environmental compatibility, and high residues, developing new, highly efficient, low-risk, and safe agricultural fungicides is an important research direction in the field of pesticide creation.

[0003] Pleuromutilin is a fungus derived from the genus Pleurotus in the class Basidiomycetes (such as...). Pleurotus mutilus and P. passeckerianusThe diterpenoid antibacterial compound isolated from [the group] was first discovered to have inhibitory activity against Staphylococcus aureus in 1951. In 1966, its core structure was identified as a unique 5-6-8 tricyclic skeleton with functional groups such as glycolate, carbonyl, secondary hydroxyl, and vinyl groups attached. Subsequently, its absolute configuration was resolved by X-ray single-crystal diffraction, determining the stereochemistry of the eight chiral carbons on the parent core. 4R, 5R, 6S, 9S, 10R, 11S, 12S, 14RThanks to its unique mechanism of action, good antibacterial activity, and low tendency to induce drug resistance, truncated pleuromedullary compounds have become one of the important lead compounds in antibacterial drug development. Several commercially available drugs have been successfully developed based on truncated pleuromedullary compounds, such as tiamulin and valnemulin for treating livestock and poultry diseases caused by Gram-positive bacteria, mycoplasma, and spirochetes, and retapamulin and lefamulin for treating Staphylococcus aureus. However, research on truncated pleuromedullary compounds and their derivatives has mainly focused on veterinary and pharmaceutical fields, with relatively few reports on their application in the pesticide field. The thioether structure plays a key role in optimizing the bioactivity of lead compounds, and its value mainly stems from the unique physicochemical properties of the sulfur atom. First, sulfur atoms possess lone pairs of electrons and polarizable 3d empty orbitals, enabling unique coordination or polar interactions with metal ions (such as Mg²⁺ and Zn²⁺) or specific amino acid residues (such as histidine and cysteine) in pathogen target proteins, thereby enhancing the binding affinity between the molecule and the target. Second, compared to their corresponding oxyethers, thioether structures typically impart superior lipophilicity (increased LogP values), significantly promoting the dual penetration of the agent into both the plant epidermis and bacterial cell membranes. This facilitates the transport and accumulation of active ingredients within the plant and bacteria, ultimately resulting in enhanced efficacy. In terms of pharmacokinetics, CS bonds generally exhibit higher metabolic stability in vivo compared to CO bonds, effectively slowing down the degradation rate of the molecule and thus prolonging its duration of action. This characteristic is crucial for controlling systemic diseases (such as vascular diseases). Introducing a thioether structure significantly enhances the systemic conductivity of the molecule, enabling it to be transported atopically or basally from the application site to the entire plant, achieving effective treatment against pathogens that have invaded vascular tissues. Furthermore, the thioether group may participate in complex bioactivation processes. For example, it can be oxidized at its action site by specific enzymes, sequentially generating more reactive metabolites such as sulfoxides or sulfones. This multi-step, multi-morphological mechanism of action can create multi-target interference against pathogens, not only enhancing the fungicidal spectrum but also effectively reducing the risk of resistance development, providing a strategic advantage for the sustainable design of novel fungicides. In summary, introducing a thioether structure into the core of truncated pleurotin, particularly modifying the C14 position with a thioether, is a highly promising innovative strategy. This design is expected to combine the unique mechanism of action of truncated pleurotin with the numerous advantages of the thioether group, creating novel agricultural fungicides with excellent permeability, systemic properties, environmental stability, and low risk of cross-resistance, providing a completely new solution for bacterial diseases such as rice bacterial blight.In 2023, our team applied for "a truncated pleurotin suspension and its preparation method" and "a truncated pleurotin wettable powder and its preparation method". In 2025, we applied for "a preparation method and use of an ester-containing truncated pleurotin derivative". The formulation has a high efficacy in controlling various agricultural diseases such as rice bacterial blight. Field trials for pesticide registration have been carried out in Hunan, Guizhou, Guangxi Zhuang Autonomous Region, Hainan, Jiangsu, Zhejiang and Anhui provinces to control rice bacterial blight, rice bacterial leaf streak and citrus canker. Experimental results showed that in the control of rice bacterial blight and rice bacterial leaf streak, the average control efficacy of 20% truncated pleurotin suspension at 300 g / ha (63.40%) was superior to or equivalent to that of the control agent 20% thiamethoxam suspension. In the control of citrus canker, 20% chloroacetyl truncated pleurotin (chloramphenicol) suspension at a dilution of 500 times showed the best control efficacy, followed by 20% chloramphenicol suspension at a dilution of 750 times and 20% chloramphenicol suspension at a dilution of 1000 times. The control efficacy of 20% thiamethoxam suspension at a dilution of 1000 times and 25% oligosaccharide ethoxysulfate microemulsion at a dilution of 500 times was relatively low, at 63.05% and 58.65% respectively, significantly lower than that of 20% chloramphenicol suspension at various concentrations. Therefore, structural modification of truncated pleurotin has broad prospects for application in agricultural antibacterial applications. We used truncated pleurotin as a lead derivatization design in order to screen for novel truncated pleurotin derivatives with higher activity. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for preparing and applying thioether-containing truncated pleurotin derivatives, by introducing a thioether structure into the C14 side chain as a flexible chain for splicing to synthesize thioether-containing truncated pleurotin derivatives.

[0005] Another object of the present invention is to provide intermediate compounds for preparing the above-mentioned compounds or their stereoisomers and methods thereof.

[0006] Another object of the present invention is to provide a compound containing the above-mentioned compound or its stereoisomer.

[0007] Another object of the present invention is to provide the use of the above-mentioned compound or its stereoisomer, or the composition thereof.

[0008] Another object of the present invention is to provide a method for controlling agricultural pests and diseases using the above-mentioned compound or its stereoisomers, or the composition thereof.

[0009] To achieve the above objectives, this application provides the following technical solution: A thioether-containing truncated pleurotin derivative or its stereoisomer, with the following general structural formula: ; In the formula: R is selected from hydrogen, alkyl or alkylene groups that are substituted or unsubstituted, alkenyl groups that are substituted or unsubstituted, aromatic groups that are substituted or unsubstituted, heteroaromatic groups that are substituted or unsubstituted, alkoxy groups that are substituted or unsubstituted, and ester groups that are substituted or unsubstituted.

[0010] The substitution refers to substitution by mercapto, halogen, methoxy, or 4-chlorophenyl mercapto.

[0011] Preferably, R is selected from methyl, ethyl, phenyl, , , , , , , , , , .

[0012] More preferably, the compounds are selected from the following specific compounds: Compound H1 ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propylcyclopentane[8]-5-yl-2-(2-((5-mercapto-1,3,4-thiadiazol-2-yl)thio)acetoxy)acetate; Compound H2: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((4-bromophenyl)thio)acetoxy)acetate; Compound H3: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldodecyl-4,9a-propylcyclopentane[8]-5-yl-2-(2-(p-tolylthio)acetoxy)acetate; Compound H4: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((4-fluorophenyl)thio)acetoxy)acetate; Compound H5: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((4-chlorophenyl)thio)acetoxy)acetate; Compound H6: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-(methylthio)acetoxy)acetate; Compound H7: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-(ethio)acetoxy)acetate; Compound H9: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((3,5-dimethylphenyl)thio)acetoxy)acetate; Compound H10: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((2,4-dimethylphenyl)thio)acetoxy)acetate; Compound H11: 2-((( 3aR,4R,5R, 7S,8S,9R,9aS,1 2R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propane[8]-5-yl)oxy)-2-oxyethylbenzoate; Compound H12: (3aR,4R,5R,7S,8S,9R,9aS,12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((3-chlorophenyl)thio)acetoxy)acetate; Compound H13: (3aR,4R,5R,7S,8S,9R,9aS,12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((3-methoxyphenyl)thio)acetoxy)acetate. This application also provides a thioether-containing truncated pleurotin derivative or its stereoisomer, comprising the following steps: (1) Using chlorpyrifos ester and substituted thiol compounds as raw materials, solvent and acid-binding agent were added, and the reaction was carried out at room temperature. After the reaction was completed, solid impurities were removed by filtration, solvent was removed by rotary evaporation, and thioether-containing truncated pleurotin derivatives were obtained by column chromatography.

[0013] ; (2) Using a mercapto-containing compound and ethyl bromoacetate as raw materials and acetonitrile as solvent, a substitution reaction was carried out under reflux at 80°C. After 12 hours of reaction, the intermediate was obtained by filtration, rotary drying, hydrolysis and acidification, and drying. Second step: The intermediate and truncated pleurotin were used as raw materials. In the presence of 4-dimethylaminopyridine (DMAP) and N,N'-dicyclohexylcarbodiimide (DCC) as ester condensing agents and dichloromethane as solvent, a reverse esterification reaction was carried out at room temperature. The H series compounds were obtained after 24 hours.

[0014] ; In the formula, X represents S.

[0015] This application also provides a composition comprising the aforementioned thioether-containing truncated pleurotin derivatives or their stereoisomers and agricultural chemical adjuvants; the dosage form of the composition is an emulsifiable concentrate wettable powder, a water-dispersible granule, a suspension concentrate, an emulsion, a microcapsule suspension, a soluble powder, an ultra-low volume liquid, a granule, or a fumigant.

[0016] This application also provides the use of the aforementioned thioether-containing truncated pleurotin derivatives or their stereoisomers, or the aforementioned compositions, in the preparation of agents for the prevention and control of plant diseases and pests; wherein the plant diseases and pests are bacterial plant diseases; wherein the bacterial plant diseases are selected from rice bacterial leaf blight, rice bacterial leaf streak, or citrus canker.

[0017] This application also provides a method for controlling agricultural pests and diseases, the method comprising applying an effective amount of the thioether-containing truncated pleurotin derivative or its stereoisomer, or the composition thereof, to a target pest or its habitat; wherein the agricultural pest or disease is a bacterial plant disease; and wherein the bacterial plant disease is rice bacterial leaf blight, rice bacterial leaf streak, or citrus canker.

[0018] This application also provides a method for protecting plants from agricultural pests and diseases, comprising the method steps of contacting the plant with the thioether-containing truncated pleurotin derivative or its stereoisomer, or the composition thereof.

[0019] Beneficial effects: In vitro and in vivo activity experiments have demonstrated that the thioether-containing truncated pleurotin derivatives of this invention exhibit excellent inhibition and bactericidal rates against rice bacterial leaf streak pathogen, rice bacterial blight pathogen, and citrus canker pathogen, effectively improving the control efficacy against rice bacterial leaf streak disease, rice bacterial blight disease, and citrus canker disease.

[0020] The derivatives of this invention have simple and novel structures, high yields, and short synthetic routes. Attached Figure Description

[0021] Figure 1 It is at 50μ The therapeutic activities of H7, pleurotin, thiamethoxam zinc and thiamethoxam copper against rice bacterial blight at g / mL; Figure 2 It is at 50 μ The protective activities of H7, truncated pleurotin, thiamethoxam zinc and thiamethoxam copper against rice bacterial blight at g / mL; Figure 3 It is at 50 μ The therapeutic activities of H7, chlorpyrifos, pleurotin, thiamethoxam zinc and thiamethoxam copper against bacterial leaf streak in rice at g / mL; Example Various exemplary embodiments of this application are now described in detail. This detailed description should not be considered as a limitation of this application, but rather as a more detailed description of certain aspects, features, and embodiments of this application. It should be understood that the terminology used in this application is merely for describing particular embodiments and is not intended to limit this application. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art described herein. Although only preferred methods and materials are described in this application, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this application. All raw materials and solvents used in the examples are commercially available products of the corresponding purity.

[0022] Example 1 Compound H1H1 ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propylcyclopentane[8]-5-yl-2-(2-((5-mercapto-1,3,4-thiadiazol-2-yl)thio)acetoxy)acetate: Chloramphenicol (1.00 g, 2.20 mmol) and 2,5-dimercapto-1,3,4-thiadiazole (0.495 g, 3.30 mmol) were dissolved in acetonitrile with stirring. Potassium carbonate (0.455 g, 3.30 mmol) was slowly added dropwise. The reaction was carried out at room temperature with dichloromethane (v):ethyl acetate (v) = 5:1 as the developing solvent. The reaction was developed with an iodine jar. After the reaction was complete, the reaction solution was filtered to remove potassium carbonate, and acetonitrile was removed by rotary evaporation. The compound H1 was separated by column chromatography (eluent: ethyl acetate (v): petroleum ether (v) = 5:1).

[0023] Example 2 Compound H2: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R )-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((4-bromophenyl)thio)acetoxy)acetate: Step 1: Using p-bromothiophenol (2.00 g, 10.58 mmol) and ethyl bromoacetate (2.30 g, 13.75 mmol) as raw materials, and acetonitrile as solvent, a substitution reaction was carried out under reflux at 80 °C. The developing solvent was ethyl acetate (v): petroleum ether (v) = 5:1. After the reaction, potassium carbonate was removed by filtration, acetonitrile was evaporated to dryness, ethanol was added to dissolve the mixture, and the mixture was hydrolyzed with sodium hydroxide aqueous solution, acidified with dilute hydrochloric acid, and dried to obtain the intermediate 2-((4-bromophenyl)thio)acetic acid. Step 2: Using the intermediate 2-((4-bromophenyl)thio)acetic acid (2.00 g, 8.09 mmol) and truncated pleurotin (2.36 g, 6.23 mmol) as raw materials, a substitution reaction was carried out in the presence of 4-dimethylaminopyridine (DMAP) (0.076 g, 0.623 mmol) and N,N'-dicyclohexylcarbodiimide (DCC) (1.35 g, 6.54 mmol). Using 1 mmol) as the esterification agent and dichloromethane as the solvent, a reverse esterification reaction was carried out at room temperature. The developing solvent was dichloromethane (v): ethyl acetate (v) = 5:1. The reaction was performed using an iodine tank for color development. After the reaction was completed, water and dichloromethane were added to the reaction solution for extraction. Dichloromethane was removed by rotary evaporation. The compound H2 was obtained by column chromatography (eluent: ethyl acetate (v): petroleum ether (v) = 5:1).

[0024] Example 3 Compound H3: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldodecylhydro-4,9a-propylcyclopentane-5-yl-2-(2-(p-tolylthio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of p-tolylthiophenol.

[0025] Example 2 Compound H4: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane-5-yl-2-(2-((4-fluorophenyl)thio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of p-fluorothiophenol.

[0026] Example 5 Compound H5: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((4-chlorophenyl)thio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of p-chlorothiophenol.

[0027] Example 6 Compound H6: (3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane-5-yl-2-(2-(methylthio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of bromomethane.

[0028] Example 7 Compound H7: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane-5-yl-2-(2-(ethio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of bromoethane.

[0029] Example 8 Compound H9: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane-5-yl-2-(2-((3,5-dimethylphenyl)thio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of 3,5-dimethylthiophenol.

[0030] Example 9 Compound H10: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane-5-yl-2-(2-((2,4-dimethylphenyl)thio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of 2,4-dimethylthiophenol.

[0031] Example 10 Compound H11: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl 2-(2-((2-chlorophenyl)thio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of 2-chlorothiophenol.

[0032] Example 11 Compound H12: ( 3aR,4R,5The preparation method of R, 7S,8S,9R,9aS,12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((3-chlorophenyl)thio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of 3-chlorothiophenol.

[0033] Example 12 Compound H13: ( 3aR,4R,5R, 7S,8S,9R,9aS,12R The preparation method of 8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanecyclopentane[8]-5-yl-2-(2-((3-methoxyphenyl)thio)acetoxy)acetate is as described in Example 2, except that p-bromothiophenol is replaced with an equimolar amount of 3-methoxythiophenol.

[0034] The physicochemical properties of the thioether-containing truncated pleurotin derivatives prepared in Examples 1-12 are shown in Table 1, and their nuclear magnetic resonance (NMR) spectra are also shown. 1 HNMR and carbon spectroscopy 13 The C NMR data are shown in Table 2.

[0035] Table 1. Physicochemical properties of thioether-containing truncated pleurotin derivatives prepared in Examples 1-12

[0036] Table 2. Nuclear magnetic resonance (NMR) data of the thioether-containing truncated pleurotin derivatives prepared in Examples 1-12.

[0037] Activity test example 1 In vitro antibacterial activity test: (1) Test method The in vitro bioactivity of the target compound against *Bacillus streak*, *Bacillus oryzae*, and *Bacillus canker* of rice was determined using the turbidimetric method. Eight corresponding concentration gradients were set up for EC5 analysis. 50 The value was determined and repeated three times. The specific procedure was as follows: Preparation of nutrient agar (NA) medium: Add 3 g beef extract, 5 g peptone, 1 g yeast powder, and 10 g glucose to a measuring cup, bring the volume to 1000 mL with deionized water, stir to dissolve, adjust the pH to 7.0-7.2 with 5% NaOH solution, add 16 g agar, sterilize at 121 ℃ for 20 min, and store at room temperature for later use.

[0038] Preparation of nutrient broth (NB): Add 3 g of beef extract, 5 g of peptone, 1 g of yeast powder, and 10 g of glucose to a measuring cup. Make up to 1000 mL with deionized water, stir to dissolve, adjust the pH to 7.0-7.2 with 5% NaOH solution, sterilize at 121 ℃ for 20 min, and store at room temperature for later use.

[0039] Bacterial activation: Seal sterile culture dishes containing NA medium inoculated by a streak plate and invert them in a 28°C incubator for growth. Add single colonies from the NA medium to NB medium and incubate with shaking at 28°C and 180 rpm until the logarithmic growth phase (0.6-0.8) for later use.

[0040] Preparation of the reagent: Weigh 1.0 mg of the target compound and add 1000 ml of water. μ Dissolve L of DMSO, and then add different volumes of the solution to centrifuge tubes containing 4 mL of Tween 20 (0.1%) water. Add 1 mL of the prepared reagent to each of the three sterilized 4 mL NB medium test tubes. Perform three replicates for each concentration. Take 50 μL of each solution. μ The bacterial culture of L was added to a test tube and cultured in a constant temperature shaker (28 ℃, 180 rpm) for 24–48 h until the logarithmic growth phase. The absorbance (OD) was then measured. 595 The formula for calculating its inhibition rate is as follows: Correcting OD 595 Value = OD of bacterial culture medium 595 - Sterile culture medium OD 595 The effect of the compound on the determination by turbidimetric method Xoo The in vitro bioactivity of these compounds, as shown in Table 3, indicates their activity against the EC50 of *Bacillus thuringiensis*, the causal agent of rice bacterial blight. 50 All values ​​showed excellent antibacterial activity. Among them, compounds H6 and H7 showed particularly high EC50 values. 50 The values ​​are 0.14 and 0.29 respectively. μ The concentrations of g / mL were significantly better than those of the control agent, thiabendazole copper (126.43 g / mL). μ g / mL) and thiamethoxam zinc (45.13 g / mL) μ g / mL) and the lead compound truncated pleurotin (1.33 g / mL) μ g / mL) and chlorpyrifos (0.24 g / mL) μ g / mL).

[0041] Table 3 shows the compounds in the examples. Xoo In vitro bioactivity

[0042] The effect of the compound on the determination by turbidimetric method Xoc The in vitro biological activity of the target compounds, as shown in Table 4, indicates that, except for H9 and H13, the other compounds in this series exhibit excellent antibacterial activity against *Bacillus streakae*, the pathogen causing rice leaf streak. Among them, compounds H2 and H7 show particularly high EC50 values. 50 The values ​​are 0.10 and 0.76 respectively. μ g / mL, all of which were superior to the control agent thiabendazole copper (99.32 g / mL). μ g / mL) and thiamethoxam zinc (37.21 g / mL) μ g / mL) and with the lead compound truncated pleurotin (0.42 g / mL) μ g / mL), chlorpyrifos (0.64 g / mL), chlorpyrifos ester (0.64 g / mL) μ It exhibits comparable in vitro activity (g / mL).

[0043] Table 4 shows the compound pairs in the examples. Xoc In vitro bioactivity

[0044] The turbidimetric assay was used to determine the effect of the compound on citrus canker pathogen ( ). Xac The in vitro bioactivity of compounds H7, H9, H11, and H14 was shown in Table 5. 50 The values ​​were 0.52, 0.05, 0.04, and 0.05, respectively. μ The concentrations of g / mL were significantly better than those of the control agent, thiazolium zinc (69.85 g / mL). μ (g / mL) and thiamethoxam (112.19 g / mL) μ g / mL) and the lead compound truncated pleurotin (0.89 g / mL) μ g / mL) and chlorpyrifos (0.75 g / mL) μ g / mL).

[0045] Table 5 shows the compound pairs in the examples. Xac In vitro bioactivity

[0046] Experimental Example 2: In vivo pot experiment on bacterial leaf streak of rice caused by highly active compound H7 The highly active target compound H7 was tested using the pressure osmosis method at 50 and 25 °C. μ The therapeutic effect of a concentration of g / mL on bacterial leaf streak in rice. A syringe with the needle removed was used to treat rice in the logarithmic growth phase. Xoc The bacteria permeated to approximately 1 / 3–1 / 2 of the leaf tip. Each treatment involved at least 10 leaves, repeated 3 times, with a water control included. The test compound and control agents, thiamethoxam zinc and thiamethoxam copper, were dissolved in DMSO and diluted to 50 and 25% with 60 mL of an aqueous solution containing 0.2% Tween-80, respectively. μg / mL. Spray the solution evenly onto the surface of rice leaves until droplets run off. Measure the length of leaf lesions 24 h after application and 14 days after inoculation, and calculate the protective activity of each treatment accordingly.

[0047] Experimental Example 3: In vivo pot experiment on bacterial leaf blight of rice using highly active compound H7 The leaf-cutting method was used to determine the concentration of compound H7 at 50%. μ The therapeutic and protective activities against rice bacterial blight were investigated at g / mL. Protective activity: Thiazole zinc, thiabendazole copper, pleurotin, and chlorpyrifos were used as control agents. Each agent was dissolved in DMSO and prepared into 50 g / mL solutions using 60 mL of 0.2% Tween-80 solution. μ Spray the pesticide at a concentration of g / mL evenly onto the rice leaves until droplets fall. One day later, apply a pesticide containing logarithmic growth factor. Xoo Cut off 2-3 cm of the tip of the rice leaves with scissors after applying the bacterial solution. A control group containing only water and no pesticide was also included. Each treatment had at least 10 leaves, with three replicates. Fourteen days after application, the length of lesions on the rice leaves was recorded, and the protective activity was calculated based on the lesion length. For therapeutic activity: first apply a solution containing the logarithmic growth factor... Xoo Using scissors, cut off 2-3 cm of the rice leaf tips. One day later, apply a 50% concentration of the bacterial solution. μ The agent was sprayed evenly onto the rice leaves at a concentration of g / mL until droplets fell. A control group (water) without the agent was also included. Each treatment consisted of at least 10 leaves, with three replicates. Fourteen days after application, the length of lesions on the rice leaves was recorded, and the protective activity was calculated based on the lesion length.

[0048] Table 6 shows the values ​​at 50 and 25. μ The therapeutic activity of H7 against bacterial leaf streak in rice at g / mL

[0049] at 25 and 50 μ The therapeutic activity of H7 against bacterial leaf streak in rice at g / mL is shown in Table 6 and Figure 1 As shown: at 50 μ At a concentration of 200 g / mL, H7 showed a therapeutic activity of 72.68% against bacterial leaf streak in rice, which was superior to the control agent 200 g / mL. μ g / mL thiamethoxam zinc (66.25%) and thiamethoxam copper (69.01%). Reduce the test concentration to 25 g / mL. μ At g / mL, H7 still had 59.19% therapeutic activity, which was superior to the therapeutic activity of the control drugs thiazide zinc (36.76%) and thiabendazole copper (41.73%).

[0050] Table 7 at 50μ Protective activity of H7 against rice bacterial blight at g / mL

[0051] In 50 μ The protective activity of H7 against rice bacterial blight at g / mL is shown in Table 7 and Figure 2 As shown: at 50 μ At a concentration of g / mL, H7 showed a protective activity of 78.12% against rice bacterial blight, which was superior to that at 200 g / mL. μ The control agents were thiabendazole copper (69.07%) and thiamethoxam zinc (70.70%) at a concentration of g / mL.

[0052] Table 8 at 50 μ The therapeutic activity of g / mL H7 against rice bacterial blight

[0053] Test at 50 μ The therapeutic activity of H7 against rice bacterial blight at g / mL is shown in Table 8. Figure 3 As shown: at a concentration of 50 μ At g / mL, H7 showed excellent therapeutic activity against bacterial blight of rice, with a therapeutic activity of 73.16%. Its therapeutic activity was weaker than that of pleurotin (85.32%) and chlorpyrifos (88.05%), but significantly better than that of the control agents thiamethoxam zinc (31.14%) and thiamethoxam copper (20.76%).

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A thioether-containing truncated pleurotin derivative, characterized in that, The general structural formula is as shown in formula H: ； In the formula: R is selected from methyl, ethyl, phenyl, , , , , , , , , , .

2. The method for preparing a thioether-containing truncated pleurotin derivative according to claim 1, characterized in that... Including step a or b: Step a: ； or Step b: ； In the formula, X represents S; The reaction conditions for step a are as follows: using chloroacetyl truncated pleurotin and substituted thiol compounds as raw materials, adding solvent and acid-binding agent, reacting at room temperature, filtering to remove solid impurities after the reaction, removing solvent by rotary evaporation, and separating by column chromatography to obtain thioether-containing truncated pleurotin derivatives; Step b consists of two steps: First step: using thiol-containing compounds and ethyl bromoacetate as raw materials, acetonitrile as solvent, reflux at 80℃ to undergo a substitution reaction, after reacting for 12 hours, filtering, rotary drying, hydrolysis acidification, and drying to obtain an intermediate; Second step: using the intermediate and truncated pleurotin as raw materials, in the presence of 4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide as ester condensing agents, and dichloromethane as solvent, a reverse esterification reaction is carried out at room temperature, and H-series compounds are obtained after 24 hours.

3. A composition, characterized in that... The composition is composed of a thioether-containing truncated pleurotin derivative as described in claim 1 and an agricultural chemical adjuvant; the dosage form of the composition is selected from emulsifiable concentrates, wettable powders, water-dispersible granules, suspension concentrates, water-in-oil emulsions, microcapsule suspensions, soluble powders, ultra-low volume liquids, granules, or fumigants.

4. The use of a thioether-containing truncated pleurotin derivative as described in claim 1, or the composition as described in claim 3, in the preparation of an agent for controlling plant diseases and pests; wherein the plant diseases and pests are bacterial plant diseases; wherein the bacterial plant diseases are rice bacterial leaf blight, rice bacterial leaf streak, or citrus canker.

5. A method for preventing and controlling agricultural pests and diseases, characterized in that, The method includes applying an effective amount of a thioether-containing truncated pleurotin derivative of claim 1, or the composition of claim 3, to a target pest or its habitat; the agricultural pest is a bacterial plant disease; the bacterial plant disease is rice bacterial leaf blight, rice bacterial leaf streak, or citrus canker.

6. A method for protecting plants from agricultural pests and diseases, comprising the step of contacting the plant with a thioether-containing truncated pleurotin derivative as described in claim 1, or the composition as described in claim 3.

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