Application of carbazole ring-containing natural product as agricultural bactericide in plant diseases
By using carbazole ring natural products as agricultural fungicides, the problem of reduced pesticide efficacy caused by plant pathogen resistance has been solved, achieving highly efficient control of plant diseases, especially significant effects on diseases such as rice bacterial blight.
Patent Information
- Application Number
- CN202511238685.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-01
- Publication Date
- 2026-03-17
AI Technical Summary
Existing pesticides are becoming less effective due to increased resistance in pathogens, making them less effective at controlling plant pathogens, especially bacterial diseases. This presents a challenge for the development of new pesticides.
Using carbazole ring-containing natural products as agricultural fungicides, we develop antibacterial drugs with novel structures and unique mechanisms of action, including carbazole ring alkaloids and their derivatives, for use in preparing various formulations such as emulsifiable concentrates and powders, for the prevention and control of plant diseases.
It significantly improves the inhibitory effect on plant pathogens. The EC50 value of the carbazole ring compound is better than that of the traditional agent thiabendazole copper, showing highly efficient and low-toxicity biological activity. In particular, it has a significant effect on diseases such as rice bacterial blight.
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Figure CN121673216A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of agricultural antibacterial agents, specifically to the application of carbazole ring-containing natural products in bacterial diseases of plants. Background Technology
[0002] Globally, antibiotic resistance in plant pathogens has caused enormous losses to the agricultural economy and has become an extremely serious challenge in modern agricultural production. Its severity is not only reflected in its impact on agricultural production but also involves multiple aspects such as the ecological environment. Furthermore, the control of bacterial diseases is more difficult, and the effectiveness of traditional pesticides has decreased due to increased pathogen resistance, posing challenges to the development of novel pesticides. Therefore, antibiotic resistance in plant pathogens has become a key scientific issue restricting pesticide development, urgently requiring the development of antimicrobial agents with novel structures, unique mechanisms of action, and high efficiency and low toxicity to replace traditional fungicides.
[0003] Natural products play a crucial role in the development of new pesticides. For example, commercially available plant-derived pesticides such as acanthoside, rotenone, and pyrethroids not only possess diverse chemical structures and broad biological activities, but also exhibit high selectivity, low toxicity, and easy degradation. Among these, carbazole-containing alkaloids are widely found in plants, particularly those belonging to the Rutaceae, Strychnine, and Leguminosae families. Carbazole-containing alkaloids possess broad biological activities and can effectively inhibit the growth and reproduction of plant pathogens. Currently, some carbazole-containing alkaloid compounds have been proven to have significant antibacterial activity against various plant pathogens, with diverse mechanisms of action, including disrupting the integrity of pathogen cell membranes and inhibiting their metabolic processes. Therefore, we screened a series of carbazole-containing alkaloids to investigate their activity against plant pathogens. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides a class of carbazole ring-containing natural products for use as agricultural fungicides in plant diseases, the structural formula of which is shown in formula (1): R1 is selected from: H, any substituted or unsubstituted methyl, any substituted or unsubstituted ethyl, any substituted or unsubstituted amino, any substituted or unsubstituted 5,11-dimethyl-6 H -pyrido[4,3-b], 5,11-dihydroindolo[3,2-b], substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, wherein the alkyl is a C1-C6 straight-chain or branched alkyl, the aryl is phenyl or naphthyl, and the heteroaryl is a 5-6 membered heterocyclic group containing nitrogen, oxygen or sulfur; R2 is selected from: H, any substituted or unsubstituted methyl group, any substituted or unsubstituted ethyl group, any substituted or unsubstituted acetone group; R3 is selected from: H, halogen, substituted or unsubstituted hydroxyl group, substituted or unsubstituted amino group, substituted or unsubstituted hydroxymethyl group, substituted or unsubstituted aldehyde group.
[0005] The preferred structure of the compound of this invention is as follows: The carbazole ring-containing natural products described in this invention are preferably elliptic rose alkaloids.
[0006] The plant disease is preferably rice bacterial blight pathogen.
[0007] A composition comprising a carbazole ring or its stereoisomer, its salt or its solvate as described in any one of the preceding claims.
[0008] The dosage form of the above composition is selected from: emulsifiable concentrate, powder, wettable powder, granules, aqueous solution, suspension concentrate, ultra-low volume spray, soluble powder, microcapsule, fumigant, water emulsion or water-dispersible granules.
[0009] Application of the above composition in the prevention and control of agricultural pests and diseases.
[0010] The agricultural pests and diseases mentioned are plant pathogenic diseases.
[0011] The bacterial diseases mentioned are any one of the following: rice bacterial blight fungus, citrus canker fungus, kiwifruit canker fungus, and tobacco bacterial wilt fungus; the fungal diseases mentioned are any one of the following: wheat scab, pepper wilt, rice sheath blight, and cucumber gray mold.
[0012] The beneficial effects achieved by this invention compared to existing technologies include: evaluating the in vitro antibacterial activity of elliptic rose alkaloids and their carbazole derivatives using turbidimetric analysis. Different concentrations of the compound were compared with... Xo Co-culture of bacterial cultures was performed, and the optical density (OD) value was measured to calculate the inhibition rate and EC50. 50 The results showed that the EC value of elliptic rosehip alkaloids was... 50 The value was 0.71 ± 0.12 μg / mL, significantly better than the control agent thiabendazole copper (TC). The isolated antibacterial activity of some carbazole ring-containing agents was significantly superior to the commercial control agent thiabendazole copper (TC) (EC). 50 >80.38 ± 1.36 mg / L), with an efficacy increase of up to 113 times.
[0013] Natural products containing carbazole rings exhibited certain in vitro inhibitory activity against plant pathogenic fungi (such as *Fusarium graminearum*, *Rhizoctonia solani*, and *Fusarium wilt*). At a concentration of 25 μg / mL, the inhibition rates of elliptic roseine against *Fusarium graminearum*, *Rhizoctonia solani*, and *Fusarium wilt* were 26.12%, 29.56%, and 19.89%, respectively; while the inhibition rates of C3 against *Fusarium graminearum* and *Rhizoctonia solani* were 19.78% and 23.85%, respectively.
[0014] A series of bioactivity tests showed that the carbazole-containing natural product protected by this invention exhibits excellent bioactivity against plant pathogenic bacteria. In a rice model, its protective and curative effects reached 52.75% and 47.26%, respectively. This compound possesses good drug-like properties and low toxicity, making it a potentially highly effective active compound against plant pathogenic viruses, bacteria, and fungi, with significant research value and application prospects. Attached Figure Description
[0015] Figure 1 Comparison of the in vivo antibacterial activity of elliptic rose alkaloid and TC against Xoo at a concentration of 200 μg / mL. Detailed Implementation
[0016] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0017] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0018] 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. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0019] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.
[0020] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0021] Example 1 Bioactivity tests of carbazole ring-containing natural products against plant pathogenic bacteria: The effects of the natural products elliptic roseine and carbazole derivatives on three plant pathogens (rice bacterial blight fungus) were evaluated using turbidimetric methods. Xo Citrus canker pathogens Xac ] and kiwifruit bacterial canker pathogen [ Ps. The in vitro antibacterial activity of ])
[0022] Experimental steps: 1. Prepare NB liquid culture medium (mass-volume ratio): glucose (10 g / L), yeast extract (1 g / L), beef extract (3 g / L), peptone (5 g / L), bring to volume with distilled water, adjust pH to 7.1-7.2, and sterilize. 2. Place the bacterial culture ( Xoo, Xac, Psa Inoculate into 50 mL of culture medium and incubate in a constant temperature shaker at 28℃ and 180 rpm; 3. Under aseptic conditions, a mixture of 1‰ Tween solution and drug solution was added to sterile NB medium to make final concentrations of 50 µg / mL and 25 µg / mL, respectively, with dimethyl sulfoxide (DMSO) as a blank control. 4. Add 40 µL of bacterial suspension (OD) to each tube of culture medium. 595 (nm = 0.6-0.8), continue incubation in a constant temperature shaker until the OD of the control group is reached. 595 The nm value reaches approximately 0.6; 5. Transfer 200 µL of each experimental group solution to a 96-well plate and measure the OD. 595 nm value; The final corrected data (T or C; T for drug-containing samples, C for samples containing an equal volume of DMSO solvent) were obtained by subtracting the background turbidity of the pathogen-free culture medium. The inhibition rate (I) was calculated using the following formula: I(%) = (C−T) / C×100 Table 1. Effects of elliptic roseine and twelve carbazole derivatives at different concentrations on the effects of different concentrations of these compounds on the health of the in vitro environment. Xo , Xac, Ps. inhibition rate
[0023] d TC; Thiamethoxam The in vitro antibacterial activity of elliptic roseine and its carbazole derivatives was evaluated using turbidimetric analysis. Different concentrations of the compounds were compared with... Xo Co-culture of bacterial cultures was performed, and the optical density (OD) value was measured to calculate the inhibition rate and EC50. 50 Value. The results showed that the EC value of elliptic rose alkaloids... 50 The value was 0.71 ± 0.12 μg / mL, significantly better than the control agent thiabendazole copper. Experimental results for some target compounds are shown in Table 1.
[0024] Table 2. In vitro anti-inflammatory effects of rosehip alkaloids and several carbazole derivatives. Xo Active EC 50 value
[0025] TC: Thiamethoxam EC 50 Median effective concentration (MEC) is an important indicator for evaluating the sensitivity of plant pathogens to compounds, and it is also a crucial parameter for setting the compound concentration when studying the mechanism of action of target compounds. In concentration gradient experiments, six appropriate concentrations were set using the two-fold dilution method. Finally, the inhibition rate of the agent against the plant pathogen and the agent concentration were converted into logarithmic values, and the toxicity curve was obtained through regression analysis using SPSS software to calculate the EC50. 50 As shown in Table 2, C3, C4, and C8 exhibit excellent in vitro antibacterial activity against *Rhizoctonia solani*, with C3 EC... 50 =5.33 ± 0.51 mg / L; C4 EC 50 =7.31 ± 0.23 mg / L; C5 EC 50 =6.55 ± 0.21 mg / L.
[0026] The results showed that the EC of elliptic rose alkaloids 50 The value was 0.71 ± 0.12 μg / mL, significantly better than the control agent thiabendazole copper (TC). The isolated antibacterial activity of some carbazole ring-containing agents was significantly superior to the commercial control agent thiabendazole copper (TC) (EC). 50 >80.38 ±1.36 mg / L), with an efficacy increase of up to 113 times.
[0027] Example 2 Bioactivity tests of carbazole ring-containing natural products against plant pathogenic fungi: The mycelial growth rate method, also known as the toxic medium method, is one of the routine methods for determining the toxicity of fungicides. The main principle is to mix the test agent with a culture medium and measure the toxicity of the agent by the rate at which colonies grow on the toxic medium. This example uses *Fusarium graminearum* of wheat, *Rhizoctonia solani* of rice, and *Fusarium wilt* of pepper as test subjects, with DMSO as a blank control. The specific procedures are as follows: 1) Weigh an appropriate amount of drug according to the test concentration, dissolve it with DMSO (the amount should not exceed 1% of the final toxic medium), then add 0.1% Tween 20 solution to make up to 10 mL, pour it into 90 mL of melted PDA medium, mix well, and then pour it into 9 petri dishes for later use; 2) Sterilize the punch (with an inner diameter of 5 mm) by flame, and after it cools, punch holes in the hyphae near the edge of the pre-activated strain, and use an inoculation needle to place the hyphae facet to the center of the toxic medium. After treatment, place them uniformly at 25℃ for incubation; 3) After the colony diameter of the control group grows to 5.5-6.6 cm, use the cross-cross method to determine the colony diameter of the control group and each drug treatment group; 4) Calculate the inhibition rate (%) using the following formula: Inhibition rate % = (CT) / (C-0.5)×100. Where, C is the colony diameter of the control group, T is the colony diameter of the drug treatment group, and 0.5 cm is the diameter of the inoculated mycelium.
[0028] Table 3. Inhibitory activity of carbazole ring-containing natural products against plant pathogenic fungi (25 μg / mL)
[0029] Table 3 shows that the carbazole-containing natural products exhibited certain in vitro inhibitory activity against plant pathogenic fungi (such as *Fusarium graminearum*, *Rhizoctonia solani*, and *Fusarium wilt*). At a concentration of 25 μg / mL, the inhibition rates of elliptic roseine against *Fusarium graminearum*, *Rhizoctonia solani*, and *Fusarium wilt* were 26.12%, 29.56%, and 19.89%, respectively; while the inhibition rates of C3 against *Fusarium graminearum* and *Rhizoctonia solani* were 19.78% and 23.85%, respectively.
[0030] Example 3 Natural products containing carbazole ring In vivo testing: The active compound, thiabendazole copper (TC), was used as a positive control. The therapeutic and protective effects of the rice variety 'Fengyou Xiangzhan' were evaluated after approximately 8 weeks of culture. Therapeutic performance was assessed using sterile scissors dipped in... Xo The bacterial solution scratched rice leaves. One day after infection, the leaves were evenly sprayed with 200 μg / mL of elliptical rosehip alkaloid solution, with a solution without the drug serving as a negative control. All treated plants were cultured in a constant temperature (28℃) and constant humidity (90%RH) incubator for 14 days, after which the disease index was measured. The protective effect was assessed after inoculation. XoBefore applying the bacterial solution, spray with the same concentration of pesticide. Obtain relevant disease indices 14 days later. Calculate the corresponding control effect (I) using the formula: I (%) = (C − T) / C × 100 (C and T represent the disease index of the negative control and the drug treatment, respectively) In in vivo rice tests, elliptic roseine showed good protective and curative effects against rice bacterial blight. At a dose of 200 μg / mL, the protective effect reached 52.75%, and the curative effect was 47.26%, which were nearly twice that of thiabendazole copper (protective rate 28.55%, curative rate 26.47%).
[0031] Table 4. In vivo antibacterial activity of rosehip alkaloid against rice bacterial blight pathogen at a concentration of 200 μg / mL.
[0032] Each treatment was repeated three times. a. Negative control; TC: control agent thiabendazole copper.
[0033] In vivo experiments were conducted using rice as a model to evaluate the agricultural application potential of ellipsoidal roseine. At a dose of 200 μg / mL, ellipsoidal roseine showed a preventive effect of 52.75% and a therapeutic effect of 47.26%, both superior to the control agent thiabendazole copper.
[0034] In summary, a series of bioactivity tests showed that the carbazole-containing natural product protected by this invention exhibits excellent bioactivity against plant pathogenic bacteria. In a rice model, its protective and curative effects reached 52.75% and 47.26%, respectively. This compound possesses good drug-like properties and low toxicity, making it a potentially highly effective active compound against plant pathogenic viruses, bacteria, and fungi, with significant research value and application prospects.
Claims
1. A class of natural products containing a carbazole ring characterized by: As the application of the agricultural fungicide in plant diseases, the structural formula is shown as formula (1): wherein R1is selected from the group consisting of: H, optionally substituted or unsubstituted methyl, optionally substituted or unsubstituted ethyl, optionally substituted or unsubstituted amino, optionally substituted or unsubstituted 5,11-dimethyl-6 H - pyrido[4,3-b], optionally substituted or unsubstituted 5,11-dihydroindolo[3,2-b], optionally substituted or unsubstituted alkyl, optionally substituted or unsubstituted aryl, optionally substituted or unsubstituted heteroaryl, wherein the alkyl is a C1-C6straight chain or branched alkyl, the aryl is a phenyl or naphthyl group, and the heteroaryl is a 5-6 membered heterocyclic group containing nitrogen, oxygen or sulfur; R2 is selected from H, optionally substituted or unsubstituted methyl, optionally substituted or unsubstituted ethyl, and optionally substituted or unsubstituted propionyl; R3 is selected from H, halogen, optionally substituted or unsubstituted hydroxyl, optionally substituted or unsubstituted amino, optionally substituted or unsubstituted hydroxymethyl, and optionally substituted or unsubstituted aldehyde.
2. The carbazole ring-containing natural product according to claim 1, characterized by: It has the following structure: 。 3. The carbazole ring-containing natural product according to claim 2, characterized by: The natural product containing the carbazole ring is the application of elliptic rosewood base in plant diseases.
4. The carbazole ring-containing natural product according to claim 3, characterized by: The plant disease is Xanthomonas oryzae.
5. A composition characterized in that, The composition contains the carbazole ring-containing compound or its stereoisomer, or its salt or its solvate according to any one of claims 1-4.
6. The dosage form of the composition according to claim 5 is selected from emulsifiable concentrate, powder, wettable powder, granule, aqueous agent, suspension, ultra-low volume spray, soluble powder, microcapsule, smoke agent, emulsion in water, or water dispersible granule.
7. The application of the composition according to claim 5 in preventing and treating agricultural pests and diseases.
8. Use according to claim 7, characterized in that: The agricultural pests and diseases are plant pathogenic diseases.
9. Use according to claim 8, characterized in that: The bacterial disease is any one of Xanthomonas oryzae, Xanthomonas axonopodis pv. citri, Xanthomonas axonopodis pv. persea, Pseudomonas syringae pv. tabaci, etc.; the fungal disease is any one of Gibberella zeae, Fusarium oxysporum f. sp. cubense, Rhizoctonia solani, Botrytis cinerea, etc.