Design synthesis of 8-bromo-5-substituted-1, 3, 4, 5-tetrahydrothiapyran [4, 3-b] indole derivative and application of derivative in prevention and treatment of rice sheath blight disease

Abstract

The invention discloses an 8-bromine-5-substituted-1, 3, 4, 5-tetrahydrothiapyran [4, 3-b] indole derivative, and the 8-bromine-5-substituted-1, 3, 4, 5-tetrahydrothiapyran [4, 3-b] indole derivative is 8-bromine-5-(4-chlorophenethyl)-1, 3, 4, 5-tetrahydrothiapyran [4, 3-b] indole and / or 8-bromine-5-phenethyl-1, 3, 4, 5-tetrahydrothiapyran [4, 3-b] indole. The invention further discloses a preparation method of the 8-bromine-5-substituted-1, 3, 4, 5-tetrahydrothiapyran [4, 3-b] indole derivative. The 8-bromo-5-substituted-1, 3, 4, 5-tetrahydrothiapyran [4, 3-b] indole derivative provided by the invention has the effects of inhibiting rhizoctonia solani and promoting seed germination. The compound provided by the invention not only can be used for preventing and treating rice sheath blight disease through spraying treatment, but also can be used for preventing rice seeds from carrying bacteria in a seed soaking manner, so that the rice sheath blight disease is comprehensively prevented and controlled. Besides, rice seeds are soaked in a compound solution, germination of the rice seeds can be promoted, the root length, growth vigor and fresh weight indexes of the seeds are improved, and the compound has good application prospects and value in prevention and treatment of the rice sheath blight disease.

Description

Technical Field

[0001] The present invention belongs to the technical field of pesticides, and more specifically, relates to the design and synthesis of 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives and their application in the prevention and treatment of rice sheath blight. Background Art

[0002] The problem of pest resistance caused by the long-term use of pesticides is unavoidable, so researchers need to constantly explore new varieties of pesticides with new sites and mechanisms of action. In recent years, many researchers have been committed to developing new, efficient and environmentally friendly botanical fungicides. This is because on the one hand, many natural products have excellent biological activity, but on the other hand, the extraction of natural products is difficult and it is difficult to meet the needs of human life and production in terms of quantity and quality. Therefore, the artificial synthesis of natural products or further optimization of the structure of natural products has great research and practical value.

[0003] As the main food crop in my country, rice occupies a pivotal position in the country's grain production. Rice sheath blight is a worldwide disease caused by infection with Rhizoctonia solani. In the early stage of the disease, oval dark green water-soaked spots first appear on the leaf sheath near the water surface, and then gradually expand into a cloud-like pattern. The middle part is grayish white and turns grayish green when wet. There are two ways for the initial infection of rice sheath blight: one is seed infection and the other is field sclerotia. For seeds with rice sheath blight, we need to disinfect the seeds, but the current reagents that can inhibit rice sheath blight have the problem of affecting seed germination.

[0004] In addition, the current control agent for rice sheath blight is mainly Jinggangmycin, but the long-term and large-scale use of Jinggangmycin has caused some Rhizoctonia solani to develop moderate to high levels of drug resistance, which reduces the control effect of Jinggangmycin or even makes it ineffective. Therefore, it is of great significance to develop more drugs to control rice sheath blight. Summary of the invention

[0005] The present invention aims to provide a compound that can promote seed germination and inhibit Rhizoctonia solani, and utilize the compound to achieve the purpose of comprehensively preventing and controlling rice sheath blight.

[0006] The first object of the present invention is to provide an 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivative and its application in inhibiting Rhizoctonia solani.

[0007] The second object of the present invention is to provide the use of the above 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives in promoting seed germination.

[0008] The third object of the present invention is to provide a method for promoting seed germination.

[0009] The fourth object of the present invention is to provide a product for preventing and controlling rice sheath blight.

[0010] The fifth object of the present invention is to provide a method for preventing and controlling rice sheath blight

[0011] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0012] The present invention shows that 8-bromo-5-(4-chlorophenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole and 8-bromo-5-phenethyl-1,3,4,5-tetrahydrothiopyran[4,3-b]indole are greatly improved in water solubility and antibacterial activity compared with 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole, have good antibacterial activity against rice sheath blight pathogen, have broad-spectrum antibacterial activity, and are expected to be developed into a class of antibacterial agents with broad application prospects.

[0013] The present invention provides an 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivative, wherein the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivative has a structure as shown in formula (I) or formula (II);

[0014]

[0015] Specifically, the preparation method of the 8-bromo-5-(4-chlorophenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is:

[0016] 1. Dissolve 0.5-1.5mmol 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole in 8-12mL N,N-dimethylformamide (DMF), add 1-3mmol NaH under ice bath and react for 20-40min, then add 1-2mmol 1-(2-bromoethyl)-4-chlorobenzene, remove the ice bath and react at room temperature for 2-3h;

[0017] 2. After the reaction is completed, water is added to quench the reaction, and the mixture is extracted with ethyl acetate for 2-4 times. The organic phases are combined, washed with saturated NaCl for 2-4 times, dried, filtered, concentrated, and purified by column chromatography to obtain the product.

[0018] Specifically, the preparation method of the 8-bromo-5-phenethyl-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is:

[0019] 1. Dissolve 0.5-1.5mmol 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole in 8-12mL N,N-dimethylformamide (DMF), add 1-3mmol NaH under ice bath and react for 20-40min, then add 1-2mmol (2-bromoethyl)benzene, remove the ice bath and react at room temperature for 2-3h;

[0020] 2. After the reaction is completed, water is added to quench the reaction, and the mixture is extracted with ethyl acetate for 2-4 times. The organic phases are combined, washed with saturated NaCl for 2-4 times, dried, filtered, concentrated, and purified by column chromatography to obtain the product.

[0021] As an optional embodiment, the stationary phase of the column chromatography purification is 200-300 mesh silica gel powder; the eluent is petroleum ether-ethyl acetate, with a volume ratio of petroleum ether:ethyl acetate=50:1.

[0022] The present invention has found that 8-bromo-5-(4-chlorophenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole and 8-bromo-5-phenethyl-1,3,4,5-tetrahydrothiopyran[4,3-b]indole both have the effect of inhibiting Rhizoctonia solani and promoting seed germination, and can promote the rice root length, growth vitality index and single grain fresh weight of rice seeds. Therefore, the following application scheme is claimed:

[0023] Application of the above 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives in inhibiting Rhizoctonia solani.

[0024] Application of the above 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives in the preparation of products for inhibiting Rhizoctonia solani.

[0025] Application of the above-mentioned 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives in preventing and controlling plant diseases caused by Rhizoctonia solani.

[0026] Application of the above 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives in the preparation of products for preventing and controlling plant diseases caused by Rhizoctonia solani.

[0027] Specifically, the plant diseases caused by Rhizoctonia solani include rice sheath blight.

[0028] Application of the above 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives in promoting seed germination.

[0029] Application of the above 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives in the preparation of products for promoting seed germination.

[0030] The invention provides a method for promoting seed germination, comprising soaking the seeds in a solution of the above-mentioned 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives.

[0031] Specifically, the seeds are rice seeds.

[0032] The invention provides a product for preventing and controlling rice sheath blight, which contains the above-mentioned 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives.

[0033] As an optional embodiment, the product further contains at least one of DMSO, isopropanol, ethyl acetate and N,N-dimethylformamide.

[0034] As an optional embodiment, the product further contains an emulsifier, and the emulsifier includes at least one of sodium dodecylbenzene sulfonate, sorbitan oleate polyether, EO / PO block polyether, and Tween-80.

[0035] The present invention provides a method for preventing and controlling rice sheath blight, which comprises using the above 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives or the above products to treat rice plants.

[0036] As an optional embodiment, in the method for preventing and controlling rice sheath blight, the rice plants may be treated by spraying or soaking.

[0037] The present invention has the following beneficial effects:

[0038] The present invention has found that 8-bromo-5-(4-chlorophenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole and 8-bromo-5-phenethyl-1,3,4,5-tetrahydrothiopyran[4,3-b]indole have the effects of inhibiting Rhizoctonia solani and promoting seed germination, and can promote the rice root length, growth vitality index and single grain fresh weight of rice seeds. The compounds of the present invention can not only prevent and control rice sheath blight by spraying treatment, but also prevent rice seeds from carrying Rhizoctonia solani by soaking seeds, thereby achieving comprehensive prevention and control of rice sheath blight. In addition, soaking rice seeds in the 8-bromo-5-(4-chlorophenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole or 8-bromo-5-phenethyl-1,3,4,5-tetrahydrothiopyran[4,3-b]indole compound of the present invention can promote their germination, improve the root length, growth vitality and fresh weight index of the seeds, and has a good application prospect and value in preventing and controlling rice sheath blight. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The synthetic route of compounds a-1 to a-11.

[0040] Figure 2 It is the structural formula of the bromide which can be selected in the synthesis route of compounds a-1 to a-11.

[0041] Figure 3 are the structural formulas of compounds a-1 to a-11.

[0042] Figure 4 These are the results of in vitro protection experiments of compounds a-10 and a-7 against rice sheath blight.

[0043] Figure 5 These are the results of in vitro treatment experiments of compounds a-10 and a-7 against rice sheath blight.

[0044] Figure 6 These are the results of the in vivo protection experiment of compounds a-10 and a-7 against rice sheath blight.

[0045] Figure 7 These are the results of in vivo treatment experiments of compounds a-10 and a-7 against rice sheath blight.

[0046] Figure 8 The results show the effect of compound a-10 on the germination rate of rice seeds (different letters indicate significant differences at the P=0.05 level).

[0047] Fig. 9 The results show the effect of compound a-7 on the germination rate of rice seeds (different letters indicate significant differences at the P=0.05 level).

[0048] Fig.10The results of the effect of compound a-10 on the germination index of rice seeds on the fifth day (Figure a is the average root length measurement result of rice seeds; Figure b is the growth vitality index analysis result of rice seeds; Figure c is the average single-grain fresh weight measurement result of rice seeds; different letters indicate significant differences at the P=0.05 level).

[0049] Fig.11 The results of the effect of compound a-7 on the germination index of rice seeds on the fifth day (Figure a is the average root length measurement result of rice seeds; Figure b is the growth vitality index analysis result of rice seeds; Figure c is the average single-grain fresh weight measurement result of rice seeds; different letters indicate significant differences at the P=0.05 level).

[0050] Fig.12 This is the germination status of rice seeds on the fifth day after being treated with different compounds.

[0051] Fig.13 The germination rates of rice seeds on the fifth day after treatment with different compounds (different letters indicate significant differences at the P=0.05 level).

[0052] Fig.14 The average root length of rice seeds on the fifth day under the treatments of different compounds (different letters indicate significant differences at the P=0.05 level).

[0053] Fig.15 is the growth activity index of rice seeds under different compound treatments on the fifth day (different letters indicate significant differences at the P=0.05 level).

[0054] Fig.16 The average single-grain fresh weight of rice seeds on the fifth day under the treatments of different compounds (different letters indicate significant differences at the P=0.05 level). DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0056] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0057] PDA culture medium was purchased from Haibo Biotechnology with the product number HB0233.

[0058] Example 1 Preparation of 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole and its derivatives

[0059] 1. Preparation method

[0060] The synthetic routes of compounds (a-1 to a-11) are as follows Figure 1 As shown, the bromine (R-Br) is selected from 1-bromo-4-chlorobutyl, 1-bromopentane, 4-bromobutyronitrile, 1-bromo-4-methoxybutane, 1,4-dibromobutane, 1,6-dibromohexane, (2-bromoethyl)benzene, 1-(2-bromoethyl)-4-methoxybenzene, 1-(2-bromoethyl)-4-methylbenzene, 1-(2-bromoethyl)-4-chlorobenzene or (2-bromoethyl)cyclohexane, and the structural formulas are as follows: Figure 2 As shown in Figures a to k of , the specific steps are as follows:

[0061] 1. Add bismuth nitrate pentahydrate (0.97 g, 2 mmol) to a methanol solution (50 mL) containing phenylhydrazine hydrochloride (1.45 g, 10 mmol) and tetrahydrothiopyran-4-one (1 g, 10 mmol), and heat under reflux for 3 h.

[0062] 2. After the reaction was completed, the reaction solution was cooled and washed with water and then with anhydrous MgSO 4 The product was dried, filtered, concentrated under reduced pressure, and purified by column chromatography (the stationary phase was 200-300 mesh silica gel powder; the eluent was petroleum ether-ethyl acetate, petroleum ether:ethyl acetate = 10:1 volume ratio) to obtain the compound 8-bromo-1,3,4,5-tetrahydrothiopyran [4,3-b] indole, with the structural formula shown below Figure 3 As shown in Figure 1, it is denoted as a.

[0063] 3. Dissolve 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole (267 mg, 1 mmol) in 10 mL of N,N-dimethylformamide (DMF) and add 48 mg of NaH (2 mmol) under ice bath.

[0064] 4. Continue to react in an ice bath for 30 min, then add 1.5 mmol of bromide, remove the ice bath, and react at room temperature for 2.5 h.

[0065] 5. After the reaction was completed by TLC monitoring, water was added to quench the reaction, and the mixture was extracted three times with ethyl acetate and the organic phases were combined.

[0066] 7. Wash 3 times with saturated NaCl and anhydrous MgSO 4 Dry, filter, concentrate, and purify by column chromatography (the stationary phase is 200-300 mesh silica gel powder; the eluent is petroleum ether-ethyl acetate, petroleum ether:ethyl acetate = 50:1 volume ratio) to obtain compounds (a-1 to a-11) prepared from the corresponding bromides.

[0067] 2. Preparation of products

[0068] (1) When the bromide is 1-bromo-4-chlorobutyl, 8-bromo-5-(4-chlorobutyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 The a-graph of , denoted as a-1.

[0069] (2) When 1-bromopentane is selected as the bromide, 8-bromo-5-pentyl-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 Figure b of , denoted as a-2.

[0070] (3) When 4-bromobutyronitrile is selected as the bromide, 4-(8-bromo-3,4-dihydrothiopyrano[4,3-b]indol-5(1H)-yl)butyronitrile is prepared, and the structural formula is as follows Figure 3 Figure c of , denoted as a-3.

[0071] (4) When 1-bromo-4-methoxybutane is selected as the bromide, 8-bromo-5-(4-methoxybutyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in Figure d, it is marked as a-4.

[0072] (5) When 1,4-dibromobutane is selected as the bromide, 8-bromo-5-(4-bromobutyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in Figure e, it is marked as a-5.

[0073] (6) When 1,6-dibromohexane is selected as the bromide, 8-bromo-5-(4-bromopentyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in Figure f, it is recorded as a-6.

[0074] (7) When (2-bromoethyl)benzene is selected as the bromide, 8-bromo-5-phenylethyl-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in Figure g, it is recorded as a-7.

[0075] (8) When 1-(2-bromoethyl)-4-methoxybenzene is selected as the bromide, 8-bromo-5-(4-methoxyphenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in Figure h, it is marked as a-8.

[0076] (9) When the bromide is 1-(2-bromoethyl)-4-methylbenzene, 8-bromo-5-(4-methylphenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in the i figure, it is recorded as a-9.

[0077] (10) When 1-(2-bromoethyl)-4-chlorobenzene is selected as the bromide, 8-bromo-5-(4-chlorophenethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in Figure j, it is denoted as a-10.

[0078] (11) When (2-bromoethyl)cyclohexane is selected as the bromide, 8-bromo-5-(2-cyclohexylethyl)-1,3,4,5-tetrahydrothiopyran[4,3-b]indole is prepared, and the structural formula is as follows Figure 3 As shown in the k figure, it is denoted as a-11.

[0079] Example 2 Preparation of 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole emulsifiable concentrate

[0080] 1. Solvent screening

[0081] Different solvents were used to dissolve 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole and a suitable solvent for 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole was sought. The experimental results showed that 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole was easily soluble in methanol, ethanol, acetone, ethyl acetate, ether, chloroform and toluene, but poorly soluble in water and petroleum ether.

[0082] 2. Confirmation of preparation method

[0083] Through the screening of solvents, the determination of melting point and acidity and alkalinity, the amount of raw materials for the preparation of 15% 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole emulsifiable concentrate was finally determined as shown in Table 1:

[0084] Table 1 Amount of raw materials used in the preparation of 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole

[0085] Raw material name Dosage(g) 8-Bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole 0.394 Isopropyl alcohol 0.8 Ethyl acetate 0.5 N,N-Dimethylformamide 0.2 Sodium dodecylbenzenesulfonate 0.125 Sorbitan oleate polyether HLB 10 0.125 Sorbitan oleate polyether HLB 11 0.125 EO / PO block polyether HLB 15 0.25

[0086] According to the order of the raw materials in Table 1 from top to bottom, the raw materials were mixed and shaken to obtain a stable 15% 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole emulsifiable concentrate with a total volume of about 2.5 mL.

[0087] According to different dosage requirements, the ratio of each raw material in Table 1 can be enlarged or reduced to prepare different volumes of bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole emulsifiable concentrate.

[0088] Example 3 Field control effect of 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole emulsifiable concentrate

[0089] 1. Experimental Methods

[0090] The rice sheath blight disease field was selected as the experimental field and divided into 6 plots, each corresponding to 6 treatments. The plot area was 20m 2 , repeated 4 times. The specific schemes of the 6 treatments are shown in Table 2. The rice plants at the tillering stage were treated according to the dosage in Table 2, and the foliar spray method was used to apply the pesticides, and the incidence of rice sheath blight was observed. Five points were sampled at the diagonal of each plot, 5 rice plants were sampled at each point, and 25 plants were sampled in each plot. The degree of damage symptoms on rice sheaths and leaves was graded, and the total number of plants, the number of diseased plants, and the disease level were recorded in units of plants.

[0091] Level 0: The whole plant is disease-free;

[0092] Level 1: The disease occurs on the fourth leaf and all leaf sheaths and leaves below it (the flag leaf is the first leaf);

[0093] Level 3: The disease occurs on the third leaf and the leaf sheaths and leaves below it;

[0094] Level 5: The disease occurs on the second leaf and the leaf sheaths and leaves below it;

[0095] Level 7: The flag leaf and the leaf sheaths and leaves below it are diseased;

[0096] Level 9: The whole plant is diseased and dies prematurely.

[0097] Calculation method of drug efficacy:

[0098]

[0099] Table 2 Specific schemes for different treatments

[0100]

[0101]

[0102] 2. Experimental Results

[0103] The effects of different treatments on the prevention and control of rice sheath blight in the field are shown in Table 3. The results show that 8-bromo-1,3,4,5-tetrahydrothiopyran[4,3-b]indole has the effect of preventing and controlling rice sheath blight.

[0104] Table 3 Effects of different treatments on the control of rice sheath blight in the field

[0105]

[0106] Example 4 Antibacterial Activity Experiment

[0107] The antibacterial activity of the synthesized compounds a-1 to a-11 was evaluated by mycelial growth rate method, and EC 50 calculate.

[0108] 1. Experimental Methods

[0109] A total of 11 compounds a-1 to a-11 were prepared in Example 1 as test compounds, and 1 mL of DMSO was used as solvent to prepare a concentration of 10 4 mg / L of different test compound stock solutions.

[0110] Set up treatment and control groups:

[0111] Treatment group: PDA agar medium was prepared according to the instructions, and different concentrations of the test compound stock solution were added to the unsolidified medium to prepare culture media containing different concentrations of the test compound with a concentration gradient of 50 mg / L, 25 mg / L, 12.5 mg / L, 6.25 mg / L, 3.12 mg / L, and 1.56 mg / L.

[0112] Control group: PDA agar medium was prepared according to the instructions, and the same amount of DMSO solution and corresponding concentration of wells containing DMSO as those of the treatment group were added to the unsolidified medium, and the prepared medium was used as the blank control group and the positive control group.

[0113] A 6 mm diameter Rhizoctonia solani cake was placed in the center of the culture medium of the treatment group and the control group and incubated at 28±2°C for several days. When the fungal hyphae in the blank control completely covered the culture dish, the hyphae diameter of each group was measured. The above test was repeated three times.

[0114] The formula for calculating the inhibition rate (%) of the drug on fungi is:

[0115]

[0116] Wherein, I is the inhibition rate (%), D is the diameter of the fungal cake (6 mm), C and T are the average colony diameters of mycelium in the blank control group and the treatment group, respectively.

[0117] According to the inhibition rate data, the linear fitting was performed using GraphPad Prism 8.0 software to further determine the half inhibition concentration (EC 50 ).

[0118] 2. Experimental Results

[0119] The inhibitory effects of different compounds on rice sheath blight are shown in Table 4. The results show that among the 11 target compounds synthesized, compounds a-7 and a-10 have better activities, and their EC 50 The values ​​were 7.135 and 5.227, respectively, which were comparable to the parent compound (a) EC 50 The values ​​are relatively close.

[0120] Table 4 Inhibitory effects of different compounds on rice sheath blight

[0121]

[0122]

[0123] Example 5 Leaf inoculation experiment

[0124] 1. Experimental Methods

[0125] Use 1mL DMSO as solvent to prepare mother solutions of compound a-10, compound a-7 and compound a. The mother solution concentration is 10 4 mg / L. Dissolve jinggangmycin in 1 mL DMSO and adjust the concentration with water to prepare jinggangmycin solutions of different concentrations.

[0126] Set up treatment and control groups:

[0127] Treatment group: The mother solution was diluted with 0.1% Tween 80 aqueous solution to prepare compound a-10 solution and compound a-7 solution with concentrations of 50 mg / L, 100 mg / L and 200 mg / L, respectively, and used as the treatment group solution;

[0128] Blank control group: 0.1% Tween aqueous solution (containing the same amount of DMSO) as the treated group;

[0129] Validamycin A positive control group: Validamycin A solutions with concentrations of 50 mg / L, 100 mg / L and 200 mg / L respectively;

[0130] Parent compound (a) positive control group: the mother solution was diluted with 0.1% Tween 80 aqueous solution to obtain parent compound solutions with concentrations of 50 mg / L, 100 mg / L and 200 mg / L, respectively.

[0131] Specific methods of therapeutic experiment on detached rice leaves:

[0132] Healthy and uniformly growing rice leaves were selected as the infection objects of rice sheath blight pathogen. The rice leaves were cut and cleaned with sterile water, and then placed in a culture dish for standby use (the culture dish was kept moist to prevent the rice leaves from withering). The mycelial cake of Rhizoctonia solani was placed in the center of the rice leaves to form the primary infection spots. After 24 hours of inoculation, the treatment group solution and the control group solution were sprayed on the spots of each rice leaf, and the leaves were placed in a constant temperature and humidity incubator for culture. The spot area was recorded by taking photos 12 hours after the application of the drug to observe the therapeutic effect of the compound.

[0133] Specific methods of rice detached leaf protection experiment:

[0134] Healthy and uniformly growing rice leaves were selected as the infection targets of rice sheath blight pathogens. The rice leaves were cut and cleaned with sterile water, and then placed in a culture dish for use (the culture dish was kept moist to prevent the rice leaves from withering). The surface of the detached rice leaves was sprayed with the treatment group solution and the control group solution in advance, and the leaves were dried at room temperature. Subsequently, the mycelial cakes of Rhizoctonia solani were inoculated, and the lesion area was observed and recorded after culturing in a constant temperature and humidity incubator for 36 hours.

[0135] Three parallel treatments were set up in each experiment, and the diseased area of ​​leaves was measured using Image-Pro Plus 6.0 software.

[0136]

[0137] 2. Experimental Results

[0138] The results of the in vitro protection experiment and the therapeutic experiment of compounds a-10 and a-7 against rice sheath blight are shown in Figure 4 , Figure 5 As shown in Table 5, the results show that compound a-10 and compound a-7 were subjected to leaf inoculation experiments, and the parent compound and Jinggangmycin were used as positive control agents. It was found that the in vitro treatment effects on rice at different concentrations were not significantly different from those of the parent compound, and the protective effect was better than that of the parent compound. At 200 μg / mL, the in vitro protective effect of compound a-10 (94.93%) was better than that of the parent compound (93.58%). At 100 μg / mL, the in vitro protective effects of compound a-10 (92.57%) and compound a-7 (88.85%) were better than those of the parent compound (82.09%).

[0139] Table 5 In vitro protective and therapeutic effects of target compounds on rice

[0140]

[0141]

[0142] Example 6 Potted Plant Experiment

[0143] 1. Experimental Methods

[0144] Well-growing rice plants were selected as test materials, and solutions of the treatment group and the control group were prepared according to the method of Example 5.

[0145] Specific methods of rice pot therapeutic experiment:

[0146] Slightly scratch the rice leaf sheath with a sterile syringe needle, take the mycelium balls of Rhizoctonia solani and inoculate them into the leaf sheath of the rice plant, wrap the infected part with tin foil, and culture it in a constant temperature incubator for 36 hours. Then, spray the rice plants with the solutions of the treatment group and the control group, observe the results and take pictures after drying for 24 hours.

[0147] Specific methods of rice potted protective experiment:

[0148] First, the rice plants were sprayed with the solutions of the treatment group and the control group, and the rice leaf sheaths were slightly scratched with a sterile syringe needle. The mycelial balls of Rhizoctonia solani were inoculated into the leaf sheaths of the rice plants. After 60 hours of infection, the plants were directly observed and photographed.

[0149] The rice pot experiment was repeated three times, and Image-Pro Plus 6.0 software was used to measure the vertical center length of the lesions on the stems of rice plants to represent the degree of infection of rice sheath blight pathogen, and the average value was taken for multiple groups.

[0150]

[0151] 2. Experimental Results

[0152] The results of the in vivo protection experiment and treatment experiment of compounds a-10 and a-7 against rice sheath blight are shown in Figure 6 , Figure 7 As shown in Table 6, the results showed that when compounds a-10 and a-7 were subjected to potted plant experiments, and the parent compound and jinggangmycin were used as control agents, it was found that their in vitro protective and therapeutic effects on rice at different concentrations were not significantly different from those of the control agents. Even at 200 μg / mL, the in vivo protective effect (81.76%) and in vivo therapeutic effect (78.97%) of compound a-10 were better than the in vivo protective effect (80.47%) and in vivo therapeutic effect (78.97%) of the control agent parent compound and the in vivo protective effect (78.76%) and in vivo therapeutic effect (75.32%) of the control agent jinggangmycin.

[0153] The above results indicate that compounds a-10 and a-7 have the potential to be developed into a plant protection agent for preventing the pandemic of rice sheath blight before the disease occurs in rice plants.

[0154] Table 6 In vivo protective and therapeutic effects of target compounds on rice sheath blight

[0155]

[0156] Example 7 Safety evaluation of target compound on rice seeds

[0157] 1. Experimental Methods

[0158] Conducting safety assessment experiments is helpful to understand the toxicity of the compound and regulate its use. According to the national industry standard "Guidelines for the Safety Evaluation of Pesticides on Crops", there are many contents in the safety evaluation of drugs on crops. Here, the main thing is to conduct a safety evaluation of pre-germination treatment of rice seeds, mainly including germination experiments and germination conditions of rice seeds. The seed soaking method is used to determine the germination effect of compounds a-10, a-7 and parent compound a on rice seeds. The preparation method of compound a-10, a-7 and parent compound a solution refers to Example 5, and the specific method is as follows:

[0159] After cleaning and disinfecting the rice seeds, soak them in clean water for three hours, remove the shrunken seeds floating on the water surface, and air-dry all the seeds for later use. Prepare solutions of compounds a-10 and a-7 of different concentrations (2.5, 5, 10, 25, 50, 100 mg / L) for soaking seeds, add 0.1% Tween 80 aqueous solution (containing an equal amount of DMSO) to the blank group, soak the seeds for 8 hours, select 50 seeds, wash them, and transfer them to a culture dish with filter paper prepared in advance, and record the germination rate of seeds under different treatments at 72h, 96h, and 120h, as well as the single seed fresh weight and growth vitality index on the fifth day.

[0160] Growth vitality index (%) = root length on day N × germination rate on day N × 100

[0161] Germination rate (%) = (number of germinated seeds / total number of test seeds) × 100

[0162] 2. Experimental Results

[0163] The effects of compounds a-10 and a-7 on the germination rate of rice seeds are shown in Figure 8 , Fig. 9 As shown in Table 7, the results show that the germination rate of rice seeds in the blank group reached 93% on the fifth day. When the concentration was increased to 100 mg / L, there was no significant difference between the treatment group and the blank group of the two compounds in each time period, indicating that the target compound had no effect on the germination of rice seeds.

[0164] Table 7 Average germination rate of rice seeds treated with different drug concentrations on different days (%)

[0165]

[0166] The effects of compounds a-10 and a-7 on rice seed germination indicators on the fifth day were as follows: Fig.10 , Fig.11As shown in Table 8, the results showed that compared with the blank control group, the 10-25 mg / L compound a-10 treatment can significantly increase the root length and growth vitality index of rice seeds. The 10-25 mg / L compound a-7 treatment can significantly increase the root length of rice seeds, among which the 25 mg / L compound a-7 treatment can also significantly increase the growth vitality index of seeds. The 10 mg / L compound a-7 treatment can significantly increase the single-grain fresh weight of seeds. In addition, the seed germination rate of 25 mg / L compound a-10 treatment was 96%, and the seed germination rate of 25 mg / L compound a-7 treatment was 97%, both higher than the 93% germination rate of the blank control treatment.

[0167] The above results fully demonstrate that compounds a-7 and a-10 can improve the germination rate, root length, single-grain fresh weight and growth vitality index of rice seeds. Compounds a-7 and a-10 not only have no toxic effect on the germination of rice, but have a promoting effect. They are potential seed treatment agents with good development prospects.

[0168] Table 8 Measurement results of germination indexes of rice seeds under different drug concentrations on the fifth day

[0169]

[0170] Example 8 Toxicity Study of Different Compounds on Rice Seeds

[0171] 1. Experimental Methods

[0172] The method for preparing solutions of compounds a, a-1, a-2, a-3, a-4, a-5, a-6, a-7, a-8, a-9, a-10, and a-11 can be referred to Example 5.

[0173] After cleaning and disinfecting the rice seeds, soak them in clean water for three hours, remove the shrunken seeds floating on the water surface, and air-dry all the seeds for later use. Prepare solutions of compounds a, a-1, a-2, a-3, a-4, a-5, a-6, a-7, a-8, a-9, a-10, and a-11 with a concentration of 10 mg / L for soaking the seeds respectively, add 0.1% Tween 80 aqueous solution (containing an equal amount of DMSO) to the blank control group, soak the seeds for 8 hours, select 50 seeds, wash them, and transfer them to a culture dish with filter paper prepared in advance, and record the germination rate, root length, single seed fresh weight, and growth vitality index of the seeds under different treatments on the fifth day.

[0174] 2. Experimental Results

[0175] The germination status, germination rate, average root length, growth activity index and average single grain fresh weight of rice seeds on the fifth day under different compound treatments were as follows: Fig.12 , Fig.13 , Fig.14 , Fig.15 and Fig.16 The specific data are shown in Table 9. The results show that:

[0176] From the perspective of seed germination rate, the germination rate of rice seeds treated with parent compound a and compounds a-1, a-3, a-4, a-5, a-6, a-8, a-9, and a-11 was significantly lower than that of the blank control. The germination rate of rice seeds treated with compounds a-2, a-7, and a-10 was not significantly different from that of the blank control.

[0177] From the perspective of seed root length, the root length of rice seeds treated with parent compound a and compounds a-1, a-3, a-5, and a-6 was significantly lower than that of the blank control. The root length of rice seeds treated with compounds a-2, a-4, a-8, a-9, and a-11 was not significantly different from that of the blank control, while the root length of rice seeds treated with compounds a-7 and a-10 was significantly higher than that of the blank control.

[0178] From the perspective of seed growth vigor index, the growth vigor index of rice seeds treated with parent compound a and compounds a-1, a-3, a-4, a-5, a-6, a-8, and a-9 was significantly lower than that of the blank control, while the growth vigor index of seeds treated with a-2, a-7, and a-11 was not significantly different from that of the blank control, and the growth vigor index of seeds treated with a-10 was significantly better than that of the blank control.

[0179] From the perspective of single-grain fresh weight of seeds, the single-grain fresh weight of rice seeds treated with parent compound a and compounds a-1, a-3, a-4, a-5, a-6, and a-9 was significantly lower than that of the blank control treatment, there was no significant difference between the a-2 and a-11 treatments and the blank control treatment, while the single-grain fresh weight of seeds treated with compounds a-7, a-8, and a-10 was significantly higher than that of the blank control treatment.

[0180] The above results show that:

[0181] (1) Compounds a-2, a-7, and a-10 have no toxic effects on rice seeds, and a-7 and a-10 have a promoting effect on the germination of rice seeds, and can significantly increase the root length, growth vitality index, and single-grain fresh weight of seeds. At the same time, compounds a-7 and a-10 also have good antibacterial activity, so they can be used as lead compounds for green innovative pesticides.

[0182] Compounds a-1, a-3, a-4, a-5, a-6, a-8, a-9, a-11 and the parent compound a all have certain toxic effects on rice seeds, among which the parent compound a has the most serious toxic effect on rice seeds.

[0183] (2) When modifying the structure of a compound, not all substituents can simultaneously meet the requirements of high activity and low toxicity. Compared with the parent compound a, compounds a-7 and a-10 still have good antibacterial activity under low toxicity conditions. This may be related to the electron cloud density on their 5-position substituents, which can serve as a theoretical support point for subsequent mechanism research.

[0184] Table 9 Measurement results of germination indexes of rice seeds under different compound solution treatments

[0185]

[0186] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivative, characterized in that: The 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivative has a structure as shown in formula (I) or formula (II); 2. Use of the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives according to claim 1 in inhibiting Rhizoctonia solani.

3. Use of the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,,3-b]indole derivatives according to claim 1 in the preparation of products for inhibiting Rhizoctonia solani.

4. Use of the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives according to claim 1 in preventing and controlling plant diseases caused by Rhizoctonia solani.

5. Use of the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives according to claim 1 in the preparation of products for preventing and controlling plant diseases caused by Rhizoctonia solani.

6. Use of the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,,3-b]indole derivatives according to claim 1 in promoting seed germination.

7. Use of the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives according to claim 1 in the preparation of products for promoting seed germination.

8. A method for promoting seed germination, characterized in that: The seeds are soaked in a solution of the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives according to claim 1.

9. A product for preventing and controlling rice sheath blight, characterized in that: Contains the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivative according to claim 1.

10. A method for preventing and controlling rice sheath blight, characterized in that: The rice plants are treated with the 8-bromo-5-substituted-1,3,4,5-tetrahydrothiopyran[4,3-b]indole derivatives according to claim 1 or the product according to claim 9.

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