Application of oxazole-containing sulfone derivative in resisting citrus huanglongbing

Abstract

The invention relates to the technical field of organic chemistry, in particular to an application of an oxazole-containing sulfone compound in the aspect of plant antibiosis, in particular to an application in promoting plants to resist citrus huanglongbing. The oxazole-containing sulfone compound provided by the invention has good bactericidal activity on two plant pathogenic bacteria, and a part of compounds also have good activity on citrus huanglongbing, so that the oxazole-containing sulfone compound has a good application prospect in the aspect of resisting citrus huanglongbing.

Description

Technical Field

[0001] The invention relates to the field of plant protection, and in particular to application of a sulfone compound containing oxazole in resisting citrus Huanglongbing disease. Background Art

[0002] Citrus Huanglongbing, also known as yellow tip disease, yellow wilt disease, and green fruit disease, is a systemic disease caused by infection with Candidatus Liberobacter and is one of the most devastating diseases in the citrus industry. Due to its wide range of biological activities, the oxazole ring is usually used as a main chain structure or a bridging chain to connect different reactive groups. Oxazole compounds have good antibacterial activity (Wang SL, Shi YJ, He HB, Li Y, Li Y and Dai H, Synthesis and bioactivity of novel pyrazole oxime derivatives containing oxazole ring. Chin. Chem. Lett. 2015, 26, 672-674), precisely because oxazole derivatives have a wide range of biological activities (Wang S, Song HY, Cai QF and Chen JX, Research progress of oxazole derivatives in the discovery of agricultural chemicals. J. Heterocycl. Chem. 2024, 61, 71-85). Sulfone compounds have various biological activities, especially antibacterial activity (Xu WM, Li SZ, He M, Yang S, Li XY and Li P, Synthesis and bioactivities of novel thioether / sulfone derivatives containing 1,2,3-thiadiazole and1,3,4-oxadiazole / thiadiazole moiety. Bioorg. Med. Chem. Lett. 2013, 23, 5821-5824). For example, in 2020, Wu Qiong et al. (Wu, Q.; Cai, H.; Yuan, T.; Li, SY; Gan, XH; Song, BA Novel vanillin derivatives containing a 1,3,4-thiadiazole moiety as potential antibacterialagents. Bioorg. Med. Chem. Lett. 2020, 30, 127113.) used the natural product vanillin as raw material and after nucleophilic substitution, imidization reduction, and thioetherification, they oxidized the thioether compound in ethanol solution with ammonium molybdate as a catalyst and hydrogen peroxide as an oxidant to synthesize a series of 1,3,4-thiadiazole sulfone derivatives containing vanillin.The antibacterial activity of the series of compounds was tested by turbidity method. The results showed that most of the target compounds had obvious antibacterial activity against Xanthomonas oryzae and Psoralea corylifolia, and the EC of compound 16a against the two pathogens was 2.34. 50 The values ​​were 3.14mg / L and 8.83mg / L, respectively, which were better than the control agent chlorothalonil (EC 50 67.64mg / L and 79.26mg / L respectively) and thiophanate-methyl (EC 50 87.03 mg / L and 108.99 mg / L respectively). Through the changes in physiological and biochemical indicators and bacterial morphology, it was found that compound 16a can reduce the production of extracellular polysaccharides of bacterial blight, destroy the cell membrane of bacterial blight, reduce the pathogenicity of bacterial blight and achieve antibacterial effect. In 2021, Mou et al. (Mou, HL; Shi, J.; Chen, JX; Hu, DY Synthesis, antibacterial activity and mechanism of new butenolides derivatives containing an amide moiety. Pestic. Biochem. Physiol. 2021, 178, 104913.) used fluoropyranone as the lead compound, designed and synthesized a series of new butenolide derivatives containing amide structure through multiple substitutions and ring closure reactions, and studied the antibacterial activity of the series of compounds. The results of in vitro antibacterial activity test showed that the series of compounds had certain activity against Xoo at a concentration of 50 mg / L, among which compound 4a had better antibacterial activity, and its EC 50It was 35.8 mg / L, which was better than the control drug chlorothalonil (73.5 mg / L). The results of the rice in vivo test showed that compound 4a showed good in vivo activity against rice bacterial leaf blight at 100 mg / L, with its therapeutic and protective activities of 40.9% and 48.9%, respectively, which were better than chlorothalonil (31.2% and 31.4%). The results of the mechanism study showed that compound 4a may enhance the disease resistance of rice by increasing the activity of defense enzymes. In addition, the genomic results showed that the protective activity of compound 4a against rice bacterial leaf blight may be closely related to oxidative phosphorylation and defense enzyme activity. In 2022, Yang et al. (Yang, LY; Liu, Q.; Liu, HW; Chen, D.; Li, HH; Chen, Z.; Xu, WM Synthesis and antimicrobial bioassays of 1,3,4-thiadiazole sulfone derivatives containing amide moiety: A study based on molecular dynamics (MD) simulations, MM / GBSA, and molecular docking [J]. J. Saudi Chem. Soc. 2022, 26, 101415.) designed and synthesized a series of 1,3,4-thiadiazole sulfone derivatives containing amide moiety by modifying carboxin, and studied their antibacterial activity. The results of in vitro antibacterial activity test showed that most compounds had good inhibitory activity against Xoo and Xac, among which compounds 6a and 6b had the best inhibitory activity against Xoo, with EC50 of 4.21 and 12.85 mg / L, respectively, significantly better than thiophanate-methyl (85.43 mg / L) and chlorothalonil (76.18 mg / L). The results of in vivo rice showed that the protective and therapeutic activities of compound 6a against rice bacterial blight at a concentration of 200 mg / L were 35.91 and 18.97%, respectively, lower than the control drugs thiophanate-methyl (56.87 and 34.12%) and chlorothalonil (56.90 and 37.03%). In 2023, Chen Jixiang et al. (Chen Jixiang, Luo Xin, Zhang Yong, Zou Yue, Liu Xing, Wang Sheng, Song Hongyi, Cai Qingfeng, Chen Yifang. A 1,2,4-triazolo[4,3-a]pyridine sulfone derivative, its preparation method and use. CN 116987076A) designed and synthesized a series of 1,2,4-triazolo[4,3-a]pyridine sulfone derivatives, and tested the compounds against citrus Huanglongbing. The test results show that most of the 1,2,4-triazolo[4,3-a]pyridine sulfone compounds have good anti-citrus Huanglongbing activity.Among them, the anti-citrus Huanglongbing activity of compounds A1, A2, A3, A6, A7, A8, A9, A10 and A15 was greater than 60%, and the activity of compounds A7 and A9 against citrus Huanglongbing fungi was the best, with anti-citrus Huanglongbing activities of 84.1% and 73.4%, respectively. It can be seen that the splicing of oxazole and sulfone structures plays an important role in the creation of antibacterial agents, and it also has good application prospects in the fight against citrus Huanglongbing.

[0003] At present, there are no research reports on the application of a sulfone compound containing oxazole in the prevention of citrus Huanglongbing disease at home and abroad. Summary of the invention

[0004] The purpose of the present invention is to overcome the above disadvantages and provide an application of sulfone derivatives containing oxazole in promoting plant resistance to citrus Huanglongbing.

[0005] An application of a sulfone derivative containing oxazole in preventing citrus Huanglongbing disease, wherein the general structural formula of the compound is shown in FIG:

[0006]

[0007] Among them, R 1 The 4th position of is a hydrogen atom, a fluorine atom or a chlorine atom; R 2 is methyl, ethyl, isopropyl, chlorobutyl, methylcyclopropyl, m-trifluoromethylbenzyl, 4-fluorobenzyl or 4-chlorobenzyl.

[0008] Furthermore, the above-mentioned application of sulfone derivatives containing oxazole in the prevention of citrus Huanglongbing disease, the specific compounds are as follows:

[0009] F1: 5-(4-fluorophenyl)-2-(methylsulfonyl)oxazole

[0010]

[0011] F2: 2-(Methylsulfonyl)-5-phenoxybenzoic acid

[0012]

[0013] F3: 5-(4-chlorophenyl)-2-(methylsulfonyl)oxazole

[0014] F4: 2-(Ethylsulfonyl)-5-(4-fluorophenyl)oxazole

[0015] F5: 2-(Ethylsulfonyl)-5-phenoxybenzoic acid

[0016]

[0017] F6: 5-(4-chlorophenyl)-2-(ethylsulfonyl)oxazole

[0018] F7: 5-(4-Fluorophenyl)-2-(isopropylsulfonyl)oxazole

[0019] F8: 2-(Isopropylsulfonyl)-5-phenoxybenzoic acid

[0020]

[0021] F9: 5-(4-chlorophenyl)-2-(isopropylsulfonyl)oxazole

[0022] F10: 2-((Cyclopropylmethyl)sulfonyl)-5-(4-fluorophenyl)oxazole

[0023] F11: 2-((3-chloropropyl)sulfonyl)-5-phenoxybenzoic acid

[0024]

[0025] F12: 5-(4-chlorophenyl)-2-((3-chloropropyl)sulfonyl)oxazole

[0026] F13: 5-(4-Fluorophenyl)-2-((3-(trifluoromethyl)benzyl)sulfonyl)oxazole

[0027] F14: 5-phenyl-2-((3-(trifluoromethyl)benzyl)sulfonyl)oxazole

[0028] F15: 5-(4-Chlorophenyl)-2-((3-(trifluoromethyl)benzyl)sulfonyl)oxazole

[0029] F16: 2-((4-fluorobenzyl)sulfonyl)-5-(4-fluorophenyl)oxazole

[0030] F17: 2-((4-Fluorobenzyl)sulfonyl)-5-phenoxybenzoic acid

[0031] F18: 5-(4-chlorophenyl)-2-((4-fluorobenzyl)sulfonyl)oxazole

[0032] F19: 2-((4-chlorobenzyl)sulfonyl)-5-(4-fluorophenyl)oxazole

[0033] F20: 2-((4-chlorobenzyl)sulfonyl)-5-phenoxybenzoic acid

[0034] F21: 2-((4-chlorobenzyl)sulfonyl)-5-(4-chlorophenyl)oxazole

[0035]

[0036] Beneficial effects:

[0037] The sulfone derivative containing oxazole of the present invention has therapeutic activity on citrus infected with Huanglongbing through anti-citrus Huanglongbing activity test and anti-citrus Huanglongbing in vivo activity test, and can be used as a potential antibacterial agent. DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments, and any improvement or substitution based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0039] Example 1: Anti-citrus Huanglongbing Activity Test

[0040] (1) Sample processing

[0041] Drug preparation: weigh 1 mg of the drug in a 1.5 mL centrifuge tube, add 100 μL of dimethyl sulfoxide to dissolve, transfer to a 15 mL centrifuge tube, and finally add 4.9 mL of 0.1% Tween 80 to prepare a 200 mg / L drug solution. Select branches with similar growth from the collected diseased branches and put them into a 50 mL centrifuge tube. Select one branch for each sample, add 10 mL of deionized water for cultivation, and evenly spray the nutrient solution until the leaves are wet. One hour later, the right half of the branch leaves are evenly coated with the prepared agent with a brush, and the left half of the leaves are coated with the same treatment solvent without the drug as a control (CK), and placed in a constant temperature incubator for cultivation (24 ° C, 95% RH, 12 h light, 12 h dark); after 3 days of cultivation, take out the treated branches, pick three leaves from each branch, collect the left and right halves of the leaves, wrap them with tin foil and label them, and store them at -80 ° C after quick freezing with liquid nitrogen.

[0042] (2) Relative quantitative analysis of citrus Huanglongbing pathogen

[0043] Grind the treated leaves into powder in liquid nitrogen, put 50-100 mg into a sterilized 1.5 mL centrifuge tube, add 800 μL of rut-mate, shake thoroughly, let stand for 5 minutes, and centrifuge for 5 minutes (12000 rpm, 4°C). Pipette 500 μL of supernatant into a 1.5 mL centrifuge tube (RNase-free), add 500 μL of trizol and mix thoroughly, let stand for 5 minutes, add 200 μL of chloroform, shake vigorously, let stand for 5 minutes, and centrifuge for 15 minutes (12000 rpm, 4°C); Pipette 500 μL of supernatant into a new centrifuge tube, add 500 μL of isopropanol, mix thoroughly by turning upside down, place on ice for 15 minutes, and centrifuge for 10 minutes (12000 rpm, 4°C); discard the supernatant, add 800 μL Wash with 75% ethanol and centrifuge for 10 min (12000 rpm, 4°C); pour off the ethanol, centrifuge for 1 min (12000 rpm, 4°C), absorb the residual water in the centrifuge tube, place at room temperature for 10 min, add 10 μL sterilized and enzyme-free water to dissolve RNA; determine the RNA concentration, use it as a template, reverse transcribe it into cDNA using reverse transcriptase (program: 30°C 10 min; 42°C 60 min; 70°C 15 min; 4°C forever), and then perform PCR amplification (95°C 2 min; 95°C 20 s, 57°C 30 s, 70°C 30 s, 40 cycles), and obtain the gene expression level by calculating the 2∧-△△Cq value.

[0044] Table 1. Determination of therapeutic activity of a sulfone derivative containing oxazole against Huanglongbing

[0045]

[0046]

[0047] Note: a Penicillin; b Streptomycin; Values ​​are mean ± standard deviation.

[0048] The results shown in Table 1 show that some compounds have good therapeutic activity against citrus Huanglongbing, among which compounds F2 and F18 have therapeutic activities of 66.9% and 82.4%, respectively.

[0049] Test Example 2: In vivo activity test against citrus Huanglongbing

[0050] Real-time fluorescence quantitative PCR method was used. Real-time fluorescence quantitative PCR method was used. Compound E was weighed and prepared into a concentration of 200 mg / L. Under greenhouse conditions, three branches with similar growth were selected, and the right half of the leaves of the branches were evenly coated with the prepared agent with a brush on the first and fifth days, respectively. At the same time, the left half of the leaves were coated with the same treatment solvent without the drug as the control group (CK). Finally, on the 10th day, the left and right halves of the leaves were collected, wrapped with tin foil and labeled, quickly frozen in liquid nitrogen, and then transferred to a -80℃ refrigerator for storage. Total citrus RNA was extracted using Trizol reagent, and the RNA concentration and quality were determined using ScanDrοp2 Ultra micro protein and nucleic acid analyzer. The RNA was used as a template and reverse transcribed into cDNA using reverse transcriptase (program: 30°C 10 min; 42°C 60 min; 70°C 15 min; 4°C forever). Primers (CL-as-forward: 5'-TCGAGCGCGTATGCAATACG-37, CL As-reverse: 57-GCGTTATCCCGTAGAAAAAGGTA-37, Action-forward: 5'GGTATTGCCGACCGTATGAG-3', Action-reverse: 5'-TGGAAGGTGCTGAGGGATG-3') were used for PCR amplification (95°C 2 min; 95°C 20 s, 57°C 30 s, 70°C 30 s, 40 cycles), and finally the in vivo activity of the compounds against citrus Huanglongbing was calculated (as shown in Table 2).

[0051] Table 2. Determination of the therapeutic activity of compound F18 against Huanglongbing

[0052]

[0053] The results shown in Table 2 indicate that at concentrations of 200 mg / L and 500 mg / L, compound F18 had a certain therapeutic activity against citrus Huanglongbing 10 days after treatment of susceptible citrus leaves.

Claims

1. Application of sulfone derivatives containing oxazole in the prevention of citrus Huanglongbing disease.

2. The use of a sulfone derivative containing oxazole in the prevention of citrus Huanglongbing according to claim 1, wherein the general structural formula of the compound is as shown in 1: in, R 1 The 4th position of is a hydrogen atom, a fluorine atom or a chlorine atom; R 2 is methyl, ethyl, isopropyl, chlorobutyl, methylcyclopropyl, m-trifluoromethylbenzyl, 4-fluorobenzyl or 4-chlorobenzyl.

3. The use of a sulfone derivative containing oxazole in preventing citrus Huanglongbing as claimed in claim 2, characterized in that: The sulfone derivatives containing oxazole include but are not limited to: F1: 5-(4-fluorophenyl)-2-(methylsulfonyl)oxazole F2: 2-(Methylsulfonyl)-5-phenoxybenzoic acid F3: 5-(4-chlorophenyl)-2-(methylsulfonyl)oxazole F4: 2-(Ethylsulfonyl)-5-(4-fluorophenyl)oxazole F5: 2-(Ethylsulfonyl)-5-phenoxybenzoic acid F6: 5-(4-chlorophenyl)-2-(ethylsulfonyl)oxazole F7: 5-(4-Fluorophenyl)-2-(isopropylsulfonyl)oxazole F8: 2-(Isopropylsulfonyl)-5-phenoxybenzoic acid F9: 5-(4-chlorophenyl)-2-(isopropylsulfonyl)oxazole F10: 2-((Cyclopropylmethyl)sulfonyl)-5-(4-fluorophenyl)oxazole F11: 2-((3-chloropropyl)sulfonyl)-5-phenoxybenzoic acid F12: 5-(4-chlorophenyl)-2-((3-chloropropyl)sulfonyl)oxazole F13: 5-(4-Fluorophenyl)-2-((3-(trifluoromethyl)benzyl)sulfonyl)oxazole F14: 5-phenyl-2-((3-(trifluoromethyl)benzyl)sulfonyl)oxazole F15: 5-(4-Chlorophenyl)-2-((3-(trifluoromethyl)benzyl)sulfonyl)oxazole F16: 2-((4-fluorobenzyl)sulfonyl)-5-(4-fluorophenyl)oxazole F17: 2-((4-Fluorobenzyl)sulfonyl)-5-phenoxybenzoic acid F18: 5-(4-chlorophenyl)-2-((4-fluorobenzyl)sulfonyl)oxazole F19: 2-((4-chlorobenzyl)sulfonyl)-5-(4-fluorophenyl)oxazole F20: 2-((4-chlorobenzyl)sulfonyl)-5-phenoxybenzoic acid F21: 2-((4-chlorobenzyl)sulfonyl)-5-(4-chlorophenyl)oxazole

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