Application of a 1,3,4-oxadiazole sulfone compound in resisting citrus huanglongbing

Abstract

Application of a 1,3,4-oxadiazole sulfone compound of the present invention in plant antibacterial, especially in promoting plant resistance to Huanglongbing of citrus. The general structural formula of the compound is shown as I, wherein n is 1, 2 or 3; X is CO or S(O) 2 ; R is methyl, ethyl or propyl; R 1 is benzene, toluene, phenyl ether, nitrobenzene, (trifluoromethyl)benzene, fluorobenzene, chlorobenzene, bromobenzene, 2,7-dichloroquinoline, 7-chloro-1-cyclopropyl-6-fluoro-1,8-naphthyridin-4(1H)-one, 2,3-dihydrobenzo[b][1,4]dioxin, 2-chloroquinoline or 4-difluoromethyl-1-methylpyrazole.

Description

Technical Field

[0001] The present invention belongs to the field of plant protection, and particularly relates to the application of a 1,3,4-oxadiazole sulfone compound in the control of citrus huanglongbing. Background Art

[0002] 1,3,4-oxadiazole sulfone compounds are a class of compounds with a wide range of biological activities (i.e., the compounds described in CN102079730). In terms of agricultural biological activities, they have activities such as insecticidal, antibacterial, antifungal, and antiviral against plants. In terms of antibacterial activity, compounds containing the 1,3,4-oxadiazole sulfone structure are a class of structures that have been studied more. For example, in 2012, Xu Weiming et al. (J. Agric. Food Chem. 2012, 60(4), 1036-1041) reported the antibacterial activity of a series of phenyl-substituted 1,3,4-oxadiazole sulfone compounds against Ralstonia solanacearum. At 500 mg / L, they had varying degrees of control effects on tobacco bacterial wilt; in 2013, Li Pei et al. (Chem. Bio. Drug Des. 2013, 82(5), 546-556) reported a series of sulfone compounds containing the 1,3,4-oxadiazole structure, and these compounds had a high inhibitory effect on the growth of Ralstonia solanacearum in tomatoes and tobacco; in 2014, Li Pei et al. (Bioorg. Med. Chem. Lett. 2014, 24(7), 677-1680) reported a series of 2,5-substituted-1,3,4-oxadiazole / thiadiazole sulfone derivatives. This series of compounds had good antibacterial activity against Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola at a concentration of 100 mg / L. In vivo antibacterial activity tests under greenhouse conditions showed that the control effects of compounds 2-(methylsulfonyl)-5-(4-fluorobenzyl)-1,3,4-oxadiazole and 2-(methylsulfonyl)-5-(2,4-dichlorobenzyl)-1,3,4-oxadiazole on rice bacterial blight at a concentration of 100 mg / L were 43.5% and 42.4% respectively, both better than the control agents bismerthiazol (25.5%) and thiodiazole copper (37.5%); in 2015, Li Shi et al. (Molecules, 2015, 20(7), 11660-11675) reported that a series of sulfone derivatives containing the 1,3,4-oxadiazole moiety had varying degrees of antibacterial activity against Xanthomonas oryzae pv. oryzae. The therapeutic activity of compound 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole against rice bacterial blight at 200 mg / L was 38.17%, better than the control agents bismerthiazol (30.21%) and thiodiazole copper (29.51%); in 2016, Wang Peiyi et al. (Bioorg. Med. Chem. Lett. 2016, 26(4), 1214-1217) reported a series of sulfone-based 1,3,4-oxadiazole pyridinium salt compounds. These compounds had good inhibitory activity against Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Xanthomonas citri subsp. citri. Some compounds had an EC 50The values are from 1.01 to 36.89 mg / L, which are superior to the control agents bismerthiazol and thiodiazole copper; in 2016, Wu Wenneng et al. (J. Heterocyclic Chem. 2016, 53(6), 2042 - 2048) reported the antibacterial activities of a series of novel oxa(thia)diazole sulfone compounds containing 6 - morpholino - substituted purines against Xanthomonas oryzae pv. oryzae and Ralstonia solanacearum. The structure showed that some compounds had good inhibitory activities against Xanthomonas oryzae pv. oryzae at 100 mg / L, which were superior to the control agents bismerthiazol and thiodiazole copper, and had moderate inhibitory activities against Ralstonia solanacearum, comparable to the commercial fungicide thiodiazole copper; in 2017, Su Shihu et al. (Molecules, 2017, 22(1), 64 - 81) reported a series of phenol - substituted 5 - sulfonyl - 1,3,4 - oxadiazole compounds, and some of these compounds had good antibacterial activities against Xanthomonas oryzae pv. oryzae and Ralstonia solanacearum; in 2017, Zheng Yutao et al. (Chin. Chem. Lett. 2017, 28(2), 253 - 256) reported a series of 2 - (sulfide / sulfone) - 5 - pyrazolyl - 1,3,4 - oxadiazole compounds. The determination results showed that at a concentration of 200 mg / L, some compounds had good antibacterial activities against Xanthomonas oryzae pv. oryzae, which were superior to the control agents bismerthiazol and thiodiazole copper; in 2018, Li Pei et al. (J. Agric. Food Chem. 2018, 66(12), 3093 - 3100) reported a series of 1,3,4 - oxadiazole sulfone compounds containing two sulfone groups. These compounds had excellent inhibitory activities against Xanthomonas oryzae pv. oryzae and Xanthomonas citri subsp. citri at a concentration of 200 mg / L. Meanwhile, the therapeutic and survival - protecting activities of 2 - ((4 - chlorophenyl)sulfonyl)methyl) - 5 - (methylsulfonyl) - 1,3,4 - oxadiazole against Xanthomonas oryzae pv. oryzae were 45.05% and 51.77% respectively, both superior to the control agents bismerthiazol (37.80% and 43.31%) and thiodiazole copper (39.89% and 44.70%); in 2020, Xiang Jie et al. (Pestic. Biochem. Phys. 2020, 170, 104695) reported a series of sulfone compounds containing isothiazole carboxamide. These compounds had good inhibitory activities against Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola at a concentration of 50 mg / L. Meanwhile, the therapeutic and protective activities of the compound 3,4 - dichloro - N - ((5 - (ethylsulfonyl) - 1,3,4 - oxadiazol - 2 - yl)methyl)isothiazole - 5 - carboxamide against Xanthomonas oryzae pv. oryzae were 41.06% and 43.99% respectively, superior to the control agents bismerthiazol (29.03% and 28.00%) and thiodiazole copper (13.41% and 15.19%); in 2020, Chen Jixiang et al. (Pest Manag. Sci.In 2020, (76(9), 3188 - 3198) reported a series of novel sulfone compounds containing 1,3,4 - oxadiazole groups. These compounds showed excellent in vitro antibacterial activity against Xanthomonas oryzae pv. oryzae at a concentration of 50 mg / L. Meanwhile, the therapeutic and protective activities of compound 2-(1-(4 - chlorophenoxy)ethyl)-5-(methylsulfonyl)-1,3,4 - oxadiazole against Xanthomonas oryzae pv. oryzae at this concentration were 46.7% and 56.4% respectively, superior to those of bismerthiazol (37.6% and 38.4%) and thiodiazole copper (28.5% and 32.5%); In 2021, Wang Shaobo et al. (J. Agric. Food Chem. 2021, 69(40), 11804 - 11815) reported cinnamic acid derivatives containing 1,3,4 - oxadiazole moieties. These compounds showed excellent inhibitory activity against Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola at a concentration of 50 mg / L. Meanwhile, the results of in vivo pot experiments showed that at a concentration of 200 mg / L, the therapeutic and protective activities of compound (E)-2-(ethylsulfonyl)-5-(4-(trifluoromethyl)styryl)-1,3,4 - oxadiazole against Xanthomonas oryzae pv. oryzae were 33.3% and 30.5% respectively, comparable to those of the control drug thiodiazole copper (32.9% and 32.0%), and superior to those of the control drug bismerthiazol (26.6% and 19.7%); In 2023, Wang Fang et al. (Arab. J. Chem. 2023, 16(2), 104479) reported a series of 1,3,4 - oxadiazole sulfone compounds with nitrogen - containing heterocyclic structures. These compounds showed excellent antibacterial activity against Xanthomonas oryzae pv. oryzae at a concentration of 100 mg / L. Meanwhile, the therapeutic and protective activities of the compounds against Xanthomonas oryzae pv. oryzae were 53.63% and 50.00% respectively, superior to those of bismerthiazol (38.18% and 39.09%) and thiodiazole copper (37.27% and 39.54%). Thus, it can be seen that 1,3,4 - oxadiazole sulfone compounds play an important role in the creation of antibacterial agents and are one of the important directions for the creation of new antibacterial agents.

[0003] Currently, there is no research report on the anti - citrus huanglongbing activity of 1,3,4 - oxadiazole sulfone compounds at home and abroad. Summary of the Invention

[0004] The purpose of the present invention is to provide an application of 1,3,4 - oxadiazole sulfone compounds in plant antibacterial, especially in promoting plant resistance to citrus huanglongbing, by overcoming the above - mentioned drawbacks.

[0005] An application of a 1,3,4 - oxadiazole sulfone compound of the present invention in anti - citrus huanglongbing, wherein the general structural formula of the compound is as shown in I:

[0006]

[0007] Among them, n is 1, 2 or 3; X is CO or S(O) 2 ; R is methyl, ethyl or propyl; R 1 is benzene, toluene, phenyl ether, nitrobenzene, (trifluoromethyl)benzene, fluorobenzene, chlorobenzene, bromobenzene, 2,7-dichloroquinoline, 7-chloro-1-cyclopropyl-6-fluoro-1,8-naphthyridin-4(1H)-one, 2,3-dihydrobenzo[b][1,4]dioxin, 2-chloroquinoline or 4-difluoromethyl-1-methylpyrazole.

[0008] Preferably, R is methyl or ethyl; R 1 is (trifluoromethyl)benzene, benzene, 7-chloro-1-cyclopropyl-6-fluoro-1,8-naphthyridin-4(1H)-one or 2,3-dihydrobenzo[b][1,4]dioxin.

[0009] The above 1,3,4-oxadiazole sulfone compound for use in controlling citrus huanglongbing, preferably the following specific compounds:

[0010] (A) N-((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-2-(trifluoromethyl)benzenesulfonamide

[0011]

[0012] (B) N-((5-(ethylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-4-(trifluoromethyl)benzenesulfonamide

[0013]

[0014] (C) N-((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)naphthalene-2-sulfonamide

[0015]

[0016] (D) N-((5-(ethylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-4-(trifluoromethyl)benzamide

[0017]

[0018] (E) 7-chloro-1-cyclopropyl-6-fluoro-N-((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide

[0019]

[0020] (F) 7-Chloro-1-cyclopropyl-6-fluoro-N-(2-(5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)ethyl)-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide

[0021]

[0022] (G) N-(2-(5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)ethyl)-2,3-dihydrobenzo[b][1,4]dioxine-5-carboxamide

[0023]

[0024] Compared with the prior art, the present invention has obvious beneficial effects. From the above technical solutions, it can be seen that the 1,3,4-oxadiazole sulfone compounds of the present invention have therapeutic activity against citrus infected with huanglongbing through anti-citrus huanglongbing activity tests and anti-citrus huanglongbing in vivo activity tests, and can be used as potential antibacterial agents. Detailed implementation manners

[0025] Test Example 1: Anti-citrus huanglongbing activity test

[0026] Real-time fluorescence quantitative PCR method was used. Real-time fluorescence quantitative PCR method was used. Penicillin and streptomycin, commonly used antibiotics in the market, were used as positive controls. Seven compounds, A, B, C, D, E, F and G, were weighed and prepared into 200 mg / L and 100 mg / L, and diseased branches with similar growth were selected and placed in a 50 mL centrifuge tube containing 10 mL deionized water. Three branches were selected for each sample, and three groups were made in parallel. Then, the quick-acting rooting liquid was evenly sprayed on the citrus leaves to be tested. After 2 hours, there were no water droplets on the citrus leaves, and the right half of the branch leaves was evenly coated with the prepared agent with a brush. At the same time, the left half of the leaf was coated with the same treatment solvent without medicine as the control group (CK), and placed in an intelligent artificial climate box for cultivation (24°C, 95% RH, 12h light, 12h dark). After 3 days of cultivation, the treated branches were removed, three leaves were picked from each branch, the left and right halves of the leaves were collected, wrapped in tin foil and labeled, quickly frozen in liquid nitrogen, and then transferred to a -80°C refrigerator for storage. Total citrus RNA was extracted using Trizol reagent, and the RNA concentration and quality were determined using ScanDrop2 Ultra micro protein and nucleic acid analyzer. The RNA was used as a template and reverse transcribed into cDNA using reverse transcriptase (program: 30℃10min; 42℃60min; 70℃15min; 4℃forever). Primers (CLas-forward: 5′-TCGAGCGCGTATGCAATA CG-3′, CLas-reverse: 5′-GCGTTATCCCGTAGAAAAAGGTA-3′, Action-forward: 5′GGTATTGCCGACCGTATGAG-3′, Action-reverse: 5′-TGGAAGGTGCTGAG GGATG-3′) were used for PCR amplification (95℃2min; 95℃20s, 57℃30s, 70℃30s, 40 cycles), and finally the therapeutic activity of the corresponding compounds against citrus Huanglongbing was calculated (as shown in Table 1).

[0027] Table 1. Anti-citrus Huanglongbing activity

[0028]

[0029]

[0030] Note: a Penicillin; b Streptomycin; values ​​are mean ± standard deviation.

[0031] The results shown in Table 1 indicate that compounds A, B, C, D, E, F and G have good therapeutic activity against citrus Huanglongbing at 200 mg / L, which are better than the control drug. A, B, C, E and G still have certain therapeutic activity against citrus Huanglongbing at 100 mg / L.

[0032] Test Example 2: In vivo Activity Test against Huanglongbing of Citrus

[0033] The real-time fluorescence quantitative PCR method was adopted. Weigh compound E and prepare it into a concentration of 200 mg / L. Under greenhouse conditions, select three branches with similar growth vigor. On the right half of the leaves of the branches, evenly apply the prepared medicament with a brush on the 1st day and the 5th day respectively. At the same time, apply the same treatment solvent without medicine on the left half of the leaves as the control group (CK). Finally, on the 10th day, collect the left and right half leaves respectively, wrap them with tin foil and label them, quickly freeze them in liquid nitrogen, and then transfer them to a -80°C refrigerator for storage. Use Trizol reagent to extract the total citrus RNA, and use the ScanDrop2 Ultra micro protein and nucleic acid analyzer to measure the RNA concentration and quality. Using it as a template, reverse transcribe it into cDNA using reverse transcriptase (procedure: 30°C for 10 min; 42°C for 60 min; 70°C for 15 min; 4°C forever), and then perform PCR amplification using primers (CL-as-forward: 5′-TCGAGCGCGTATGCAATACG-3′, CLas-reverse: 5′-GCGTTATCCC GTAGAAAAAGGTA-3′, Action-forward: 5′GGTATTGCCGACCGTATGAG-3′, Action-reverse: 5′-TGGAAGGTGCTGAGGGATG-3′) (95°C for 2 min; 95°C for 20 s, 57°C for 30 s, 70°C for 30 s, 40 cycles), and finally calculate the in vivo activity of the compound against Huanglongbing of citrus (as shown in Table 2).

[0034] Table 2. In vivo Activity Test against Huanglongbing of Citrus

[0035]

[0036]

[0037] The results shown in Table 2 indicate that at a concentration of 200 mg / L, after treating the diseased citrus leaves with compound E for 10 days, it has a certain therapeutic activity against Huanglongbing of citrus.

[0038] As mentioned above, it is only a preferred embodiment of the present invention, and there is no any form of limitation to the present invention. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. Use of a 1,3,4-oxadiazole sulfone compound in the control of citrus huanglongbing, characterized in that, the compound is one of the following: (A) N -((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-2-(trifluoromethyl)benzenesulfonamide （ ）； (B) N -((5-(ethylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-4-(trifluoromethyl)benzenesulfonamide ； (C) N -((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)naphthalene-2-sulfonamide ； (D) N -((5-(ethylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-4-(trifluoromethyl)benzamide ； (E) 7-chloro-1-cyclopropyl-6-fluoro-N-((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide ； (F) 7-chloro-1-cyclopropyl-6-fluoro-N-(2-(5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)ethyl)-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide ； (G) N- (2-(5-(Methylsulfonyl)-1,3,4-oxadiazol-2-yl)ethyl)-2,3-dihydrobenzo[b][1,4]dioxine-5-carboxamide 。 2. Use of a 1,3,4-oxadiazole sulfone compound according to claim 1 in the control of citrus huanglongbing, characterized in that, the concentration of the compound is 200 mg / L.

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