Illicium verum extract bacteriostatic agent for preventing and treating bacterial wilt and verticillium wilt

Abstract

The invention discloses an illicium verum extract bacteriostatic agent for preventing and treating bacterial wilt and verticillium wilt, and relates to the technical field of preparation of plant source bacteriostatic preparations, the illicium verum extract bacteriostatic agent comprises the following components by mass: 3 parts of illicium verum extract, 4 parts of acetone, 0.1 part of Tween 80, and water to a constant volume of 100 parts; wherein the mass ratio of illicium verum to fennel in the raw materials of the illicium verum extract is (1-2): (1-2), preferably 2: 1; the combination of illicium verum and fennel not only attacks the physical structure of pathogenic bacteria, but also interferes the metabolic pathway of pathogenic bacteria and reduces the drug resistance risk, the biological characteristics of pathogens of bacterial wilt and verticillium wilt are greatly different, anethole is more sensitive to bacterial membranes, shikimic acid has stronger inhibition on fungal metabolism, and the illicium verum and the shikimic acid are covered by different mechanisms to obtain a synergistic effect, so that the drug resistance is improved. The bacterial wilt and the verticillium wilt can be prevented and treated at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing plant-derived antibacterial agents, and particularly to an antibacterial agent extracted from star anise for preventing and controlling bacterial wilt and Verticillium wilt. Background Art

[0002] Potato bacterial wilt is a bacterial vascular disease caused by Pseudomonas solanacearum, also known as bacterial blight. It is a major disease in potato production second only to late blight. The pathogen can survive in the soil for 14 months to 6 years, has poor tolerance to dryness, and is prone to break out under high temperature and high humidity (25 - 35°C). The whole plant will wither and die within 4 - 6 days; Potato Verticillium wilt is a fungal soil-borne disease caused by Verticillium dahliae and Verticillium alboatrum, also known as early death disease. It is an important reason for yield reduction in the main potato production areas. The pathogen directly invades through the root wounds or epidermis, blocks the vascular bundles, and causes the plant to wither gradually within 12 - 15 days. Both bacterial wilt and Verticillium wilt are prone to occur in a high-humidity environment. The difference is that the temperature prone to bacterial wilt is 25 - 35°C, and the temperature prone to Verticillium wilt is 19 - 24°C. Both will have a significant impact on potato yield, resulting in a large reduction in potato production, and both are caused by microorganisms. Therefore, the best method is to carry out antibacterial and bactericidal treatments.

[0003] For example, in Chinese Patent with application number CN202010015449.0, an antibacterial agent for efficiently preventing and controlling cotton Verticillium wilt, its preparation method and application. The ratio of the provided artemisia argyi antibacterial agent composition is calculated by mass parts as follows: 1 part of artemisia argyi extract; 2 - 8 parts of acetone; 0.05 - 0.40 parts of tween 80 solution; add water to make up the total amount of the antibacterial agent. The present invention also provides a preparation method of the artemisia argyi antibacterial agent composition, and its preparation steps include two major parts: the preparation of artemisia argyi extract and the preparation of artemisia argyi antibacterial agent aqueous solution. The artemisia argyi antibacterial agent has a significant inhibitory effect on cotton Verticillium wilt pathogens. Applying the antibacterial agent to cotton plants inoculated with Verticillium wilt pathogens can effectively inhibit the infection of Verticillium wilt pathogens on cotton plants and reduce the disease index of cotton Verticillium wilt in the field. It provides a new way for the prevention and control of cotton Verticillium wilt.

[0004] However, in addition to the treatment of Verticillium wilt by the above-mentioned artemisia argyi antibacterial agent, there is no report on the antibacterial effect of artemisia argyi on Pseudomonas solanacearum of bacterial wilt, and it is also impossible to determine the significant treatment effect of artemisia argyi on Gram-negative bacilli. Therefore, a plant antibacterial agent that can have both treatment and prevention effects on Verticillium wilt and bacterial wilt is needed. Summary of the Invention

[0005] By providing an antibacterial agent of star anise extract for preventing and controlling bacterial wilt and Verticillium wilt in an embodiment of the present application, the problem in the prior art that the prevention and control of Verticillium wilt and bacterial wilt cannot be taken into account is solved, and the prevention and control of both bacterial wilt and Verticillium wilt are realized.

[0006] An embodiment of the present application provides an antibacterial agent of star anise extract for preventing and controlling bacterial wilt and Verticillium wilt. The ratio of the antibacterial agent of star anise extract is calculated by mass as follows: 3 parts of star anise extract, 4 parts of acetone, 0.1 part of Tween 80, and made up to 100 parts with water; Among them, the mass ratio of star anise to fennel in the raw material of the star anise extract is (1 - 2):(1 - 2).

[0007] Furthermore, the preparation steps of the star anise extract are as follows: S1. Take dry star anise and fennel, crush them respectively with a high-speed crusher, pass through a 40-mesh sieve, remove the fibrous part, and retain the uniform powder crude product; S2. Mix the two crude products with ethanol according to a solid-liquid ratio of 1:8, soak them cold for 24 hours, and stir once every 6 hours; and perform ultrasonic treatment with an ultrasonic instrument. The power of the ultrasonic instrument is 300 W, the temperature is 30 °C, and the extraction time is 40 min; filter the filtrate, collect the filtrate, and re-soak and ultrasonically extract the filter residue at a solid-liquid ratio of 1:4, and combine the two filtrates; S3. Concentrate the combined filtrate to an extract, and vacuum dry to obtain the star anise extract.

[0008] Furthermore, the preparation method of the antibacterial agent of star anise extract is: mix the formulated amount of star anise extract and acetone under ultrasonic conditions. The ultrasonic conditions are 240 W, the temperature is 25 °C, and the time is 30 min; then add Tween 80 and water, and stir evenly to obtain.

[0009] Furthermore, the mass ratio of star anise to fennel in the raw material of the star anise extract is preferably 2:1.

[0010] Furthermore, in step S1, the crude product powder is also pretreated by hydroxyl activation and then subjected to an esterification reaction.

[0011] Furthermore, the hydroxyl activation pretreatment is specifically: mix the fennel powder with 5% NaOH solution according to a solid-liquid ratio of 1:10, react at 60 °C for 2 hours; filter, wash with water until neutral, and dry to obtain hydroxylated anethole.

[0012] Furthermore, the esterification reaction is specifically: mix hydroxylated anethole and shikimic acid according to a molar ratio of 1:1.2, add 1% w / w concentrated sulfuric acid and toluene, reflux and react at 80 °C for 6 hours. After the reaction is completed, cool to room temperature, neutralize with saturated NaHCO3 solution, perform liquid-liquid extraction, and collect the organic phase; remove toluene by vacuum distillation to obtain the conjugate ester crude product.

[0013] Further, 10% of anethole based on the total content is added to the crude conjugate ester product.

[0014] Further, star anise is cured in the conjugate ester.

[0015] Further, the curing process is specifically as follows: the conjugate ester and anethole are mixed at a mass ratio of 9:1, dissolved in an acetone-water mixed solvent, and magnetically stirred until completely dissolved to form a homogeneous solution. Deionized water is slowly added dropwise to the solution at a rate of 1 mL / min until the water content reaches 40%; ultrasonic homogenization treatment is carried out; The pH of the solution is adjusted to 5.5 - 6.0 with citric acid-phosphate buffer solution, and it is left standing at 4°C for 12 h. The solution is placed in a rotary evaporator and concentrated under reduced pressure to 10% of the original volume. Freeze-drying is carried out to obtain the cured conjugate ester and anethole mixture.

[0016] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: First, star anise contains shikimic acid, which is a key intermediate in the aromatic amino acid synthesis pathway. By competitively inhibiting the shikimate kinase of pathogenic bacteria, it blocks the synthesis of their essential amino acids, inhibits growth, and has an inhibitory effect on both bacteria and fungi that rely on this pathway; it activates the systemic acquired resistance of potatoes, upregulates the expression of defense genes, and enhances the immunity of plants to pathogenic bacteria; fennel contains anethole, which is a fat-soluble compound that can penetrate the cell membranes of bacteria and fungi, causing the rupture of the membrane structure and the leakage of contents, and can also interfere with the energy metabolism-related enzyme (ATPase) of pathogenic bacteria, blocking its energy supply; ultimately leading to the death of pathogenic bacteria, having broad-spectrum properties and being effective against both Gram-negative bacteria and fungi.

[0017] Second, first through base hydrolysis: the methoxy group of anethole is converted into a hydroxyl group, and then an esterification reaction is carried out with shikimic acid under acid catalysis to synthesize anethole-shikimic acid conjugate ester. Then, extraction with ethanol is carried out, which can greatly improve the total yield. Through chemical modification and process optimization, the efficient integration of anethole and shikimic acid not only improves their synergistic effect but also increases the yield; the molecular structure of the conjugate ester retains the hydrophobic group of anethole and the polar group of shikimic acid, which can directly destroy the integrity of the cell membrane or cell wall of pathogenic bacteria; and the conjugate structure reduces the molecular free energy and lowers the degradation rate; the conjugate has a moderate polarity, is easily extracted efficiently by methanol aqueous solution, and is more easily penetrated through the cell barrier of pathogenic bacteria.

[0018] Third, the conjugate ester achieves synergistic antibacterial effects by destroying the cell membrane of pathogenic bacteria and inhibiting the metabolic pathway. Free anethole independently exerts an antibacterial effect and at the same time prolongs the active life of the conjugate ester as an antioxidant.

[0019] Fourthly, dissolve lipophilic anethole with acetone, adjust the polarity with water to induce subsequent self-assembly, increase the temperature to enhance molecular movement, promote initial mixing, achieve molecular-level dispersion of anethole and conjugated ester, and lay the foundation for self-assembly; the increase in water content reduces the solvent polarity, forcing hydrophobic anethole and conjugated ester to aggregate through hydrophobic interaction, and ultrasound produces cavitation effect to break the steric hindrance between molecules, accelerate self-assembly, and form an anethole-conjugated ester complex; under nearly neutral conditions after pH regulation, the ester group is partially protonated and forms hydrogen bonds with the hydroxyl group of anethole; low-temperature static placement slows down molecular movement, promotes the orderly arrangement of hydrogen bonds, constructs a stable intermolecular hydrogen bond network, and reduces antioxidant migration. Description of the Drawings

[0020] Figure 1 It is a comparison chart of the cure rate of Verticillium wilt in Example 1; Figure 2 It is a comparison chart of the cure rate of bacterial wilt in Example 1; Figure 3 It is a comparison chart of the cure rate of Verticillium wilt in Example 2; Figure 4 It is a comparison chart of the cure rate of bacterial wilt in Example 2. Detailed Implementation Modes

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs; the terms used in the description of this invention herein are only for the purpose of describing specific implementation modes and are not intended to limit this invention; the term "and / or" used herein includes any and all combinations of one or more of the related listed items, and star anise and Chinese star anise mentioned herein both refer to the dried mature fruits of Illicium verum Hook.f. of the Magnoliaceae family; fennel refers to the dried mature fruits of Foeniculum vulgare Mill. of the Umbelliferae family.

[0022] Example 1: The present application provides an antibacterial agent of star anise extract for preventing and treating bacterial wilt and Verticillium wilt. The ratio of the antibacterial agent of star anise extract is calculated by mass as follows: 3 parts of star anise extract, 4 parts of acetone, 0.1 part of Tween 80, and made up to 100 parts with water; The preparation steps of the star anise extract are as follows: S1. Take dried star anise and fennel, respectively crush them with a high-speed crusher (5000 r / min), pass through a 40-mesh sieve, remove the fibrous part, and retain the uniform powder crude product; S2. Mix all the crude powder with ethanol (60%-80%) at a material-liquid ratio of 1:8, soak it cold for 24 hours, and stir it every 6 hours; and perform ultrasonic treatment using an ultrasonic instrument. The power of the ultrasonic instrument is 300 W, the temperature is 30 °C, and the extraction time is 40 min; filter the filtrate, collect the filtrate, and re-soak and ultrasonically extract the filter residue at a material-liquid ratio of 1:4, and combine the two filtrates; S3. Concentrate the combined filtrate to an extract, and vacuum dry it (40 °C, 48 h) to obtain the star anise extract.

[0023] The preparation method of the bacteriostatic agent is as follows: Mix the formulated amount of star anise extract and acetone under ultrasonic conditions. The ultrasonic conditions are 240 W, the temperature is 25 °C, and the time is 30 min; then add Tween 80 and water, and stir evenly to obtain it.

[0024] The technical solutions in the embodiments of the present application at least have the following technical effects or advantages: Star anise contains shikimic acid, which is a key intermediate in the aromatic amino acid synthesis pathway. By competitively inhibiting the shikimate kinase of pathogenic bacteria, it blocks the synthesis of essential amino acids, inhibits growth, and has an inhibitory effect on both bacteria and fungi that rely on this pathway; activates the systemic acquired resistance of potatoes, up-regulates the expression of defense genes, and enhances the immunity of plants to pathogenic bacteria; Fennel contains anethole, which is a lipophilic compound that can penetrate the cell membranes of bacteria and fungi, causing the rupture of the membrane structure and the leakage of contents, and can also interfere with the energy metabolism-related enzyme (ATPase) of pathogenic bacteria, blocking its energy supply; ultimately leading to the death of pathogenic bacteria, having broad-spectrum properties, and being effective against both Gram-negative bacteria (Ralstonia solanacearum) and fungi (Verticillium dahliae); Using the combination of star anise and fennel not only attacks the physical structure of pathogenic bacteria but also interferes with their metabolic pathways, reducing the risk of drug resistance. The biological characteristics of the pathogens of bacterial wilt (bacteria) and verticillium wilt (fungi) are very different. Anethole is more sensitive to bacterial membranes, while shikimic acid has a stronger inhibitory effect on fungal metabolism. Cover the two with different mechanisms to obtain a synergistic effect; perform FIC determination. In the bacteriostatic effect on Pseudomonas solanacearum, the synergistic effect is the strongest when the ratio of star anise to fennel is 2:1, and the FIC is 0.33. In the bacteriostatic effect on Verticillium dahliae, the synergistic effect is the strongest when the ratio of star anise to fennel is 2:1, and the FIC is 0.38; the ratios of star anise and fennel are all raw material ratios rather than product ratios.

[0025] The active ingredients can also jointly activate the plant endogenous disease resistance signaling pathway, enhancing the systemic defense ability of potatoes against various pathogens; The antibacterial effect was detected through field detection. The cure rate was calculated by counting the number of diseased plants before and after using the antibacterial agent. The antibacterial agent was sprayed on the leaves and irrigated at the roots, and the concentrations of the antibacterial agents used were the same. Different ratios of star anise extracts were used to detect the treatment effect. The results are as follows Figure 1 , Figure 2 .

[0026] Example 2: In the above example, star anise was used to treat potato bacterial wilt and Verticillium wilt. To improve the extraction efficiency of the two, further improvements were made on the basis of Example 1.

[0027] In step S1, the fennel powder was pretreated by hydroxy activation and then subjected to an esterification reaction; Specifically: The fennel powder was mixed with 5% NaOH solution at a solid-liquid ratio of 1:10 and reacted at 60 °C for 2 hours; filtered, washed with water until neutral, and dried to obtain hydroxylated anethole; then the hydroxylated anethole was mixed with shikimic acid in a molar ratio of 1:1.2, 1% w / w sulfuric acid and toluene (solid-liquid ratio 1:8) were added, and the mixture was refluxed at 80 °C for 6 hours. After the reaction, it was cooled to room temperature, neutralized with saturated NaHCO3 solution, separated by liquid-liquid extraction, and the organic phase was collected; toluene was removed by vacuum distillation to obtain the crude conjugate ester.

[0028] The technical solutions in the embodiments of the present application have at least the following technical effects or advantages: First, through base hydrolysis: the methoxy group (-OCH3) of anethole was converted into a hydroxyl group (-OH), and then an esterification reaction was carried out with shikimic acid under acid catalysis to synthesize anethole-shikimic acid conjugate ester. Then, ethanol extraction was carried out, which could greatly improve the total yield. Through chemical modification and process optimization, anethole and shikimic acid were efficiently integrated, not only improving their synergistic effect but also increasing the yield; the molecular structure of the conjugate ester retained the hydrophobic group of anethole and the polar group of shikimic acid, which could directly destroy the integrity of the cell membrane or cell wall of the pathogen; and the conjugated structure reduced the molecular free energy and decreased the degradation rate; the polarity of the conjugate was moderate, which was easily extracted by a mixed solvent (ethanol-water) and was more likely to penetrate the cell barrier of the pathogen; The conjugate ester inserts into the bacterial membrane through the lipophilic benzene ring, and at the same time the polar carboxylic acid ester group interferes with fungal metabolism and takes effect without decomposition; some conjugate esters slowly decompose in plants, continuously releasing anethole and shikimic acid, further enhancing the antibacterial persistence.

[0029] The formation of the conjugate ester was confirmed by detecting the characteristic peak of the ester bond (1740 cm -1 C=O stretching vibration) by FT-IR, and then the yield was calculated by HPLC. The results are shown in Table 1; in Example 1, the star anise raw material was calculated at 1:1; ; Table 1 Then, the antibacterial effect of the star anise extract bacteriostatic agent prepared in Example 2 was detected. The raw material ratio of star anise: fennel of 2:1 in Example 1 was selected as the control group. The results are as Figure 3 、 Figure 4 ; Example 3: In Example 2, the conjugated ester was obtained through an esterification reaction. However, exposing it to various environments would cause the hydrolysis of the conjugated ester. Therefore, an antioxidant component was added for further improvement based on Example 2.

[0030] Based on the conjugated ester, 10% of anethole was added to the total content of the star anise extract.

[0031] The technical solutions in the embodiments of the present application at least have the following technical effects or advantages: The conjugated ester achieves synergistic antibacterial effects by destroying the cell membranes of pathogenic bacteria and inhibiting metabolic pathways. Free anethole independently exerts an antibacterial effect and, at the same time, prolongs the active life of the conjugated ester as an antioxidant.

[0032] Through the benzene ring structure of anethole, hydrogen atoms can be provided to neutralize free radicals and block the oxidation chain reaction; anethole can bind to transition metal ions and inhibit their ability to catalyze lipid peroxidation reactions; by inhibiting the activity of oxidation-related enzymes, the generation of reactive oxygen species can be reduced; The ester bond of the conjugated ester is susceptible to hydrolysis or oxidative degradation due to factors such as light, heat, and oxygen. Adding free anethole can form an "antioxidant barrier". Free anethole preferentially reacts with oxygen free radicals to reduce the oxidative exposure of the conjugated ester; The benzene ring structures of anethole and the conjugated ester together form an intermolecular π-π stacking, enhancing the structural rigidity and reducing the hydrolysis rate.

[0033] A stability test was carried out on the conjugated ester with and without anethole added. The results are shown in Table 2; ; Table 2 Example 4: In Example 3, the stability of the conjugated ester was increased by adding anethole, thereby increasing the medicinal persistence. To exert the antioxidant effect of anethole, further improvement was made based on Example 3.

[0034] When the conjugated ester and anethole were mixed, hydrogen bond connection treatment was also carried out. Specifically: Mix the conjugate ester and anethole in a mass ratio of 9:1, dissolve them in a mixed solvent of acetone - water (80:20) (feed liquid ratio 1:15), and stir magnetically (50 °C, 2 h) until completely dissolved to form a homogeneous solution. Slowly add deionized water to the solution (rate 1 mL / min) until the water content reaches 40% (v / v); perform ultrasonic homogenization treatment (power 400 W, 30 min). Adjust the pH of the solution to 5.5 - 6.0 (citric acid - phosphate buffer) to protonate the ester group (-COO-) of the conjugate ester, and let it stand at low temperature (4 °C, 12 h) to stabilize the hydrogen bond network. Place the solution in a rotary evaporator (40 °C, 0.1 MPa) to concentrate it under reduced pressure to 10% of the original volume. Freeze - dry (-50 °C, 48 h) to obtain the conjugate ester - anethole mixture.

[0035] The technical solutions in the embodiments of the present application at least have the following technical effects or advantages: Dissolve the lipophilic anethole with acetone, adjust the polarity with water to induce subsequent self - assembly, increase the temperature to enhance molecular movement and promote initial mixing, achieving molecular - level dispersion of anethole and conjugate ester, laying a foundation for self - assembly; increasing the water content reduces the solvent polarity, forcing the hydrophobic anethole and conjugate ester to aggregate through hydrophobic interactions. Ultrasonic cavitation effect breaks the steric hindrance between molecules, accelerating self - assembly to form an anethole - conjugate ester complex; under near - neutral conditions after pH regulation, the ester group is partially protonated (-COOH) and forms hydrogen bonds with the hydroxyl group (-OH) of anethole; standing at low temperature slows down molecular movement, promotes the ordered arrangement of hydrogen bonds, constructs a stable intermolecular hydrogen bond network, and reduces antioxidant migration. The benzene ring of anethole wraps the conjugate ester through π - π stacking, reducing the oxidation exposure sites, achieving adsorption through molecular self - assembly, reducing costs and process complexity. The synergistic protection of hydrogen bonds and hydrophobic interactions further reduces the oxidation degradation rate of the conjugate ester, avoiding the use of synthetic carriers, and conforming to the principles of green chemistry. Perform stability tests on anethole and conjugate ester treated by hydrogen bond connection, and the results are shown in Table 3; ; Table 3 The above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An antibacterial agent of star anise extract for preventing and controlling bacterial wilt and Verticillium wilt, characterized in that, The formulation ratio of the star anise extract bacteriostatic agent is as follows by mass: 3 parts of star anise extract, 4 parts of acetone, 0.1 part of Tween 80, and made up to 100 parts with water; Among them, the mass ratio of star anise to fennel in the raw material of star anise extract is (1 - 2):(1 - 2).

2. The star anise extract bacteriostatic agent for preventing and treating bacterial wilt and verticillium wilt according to claim 1, characterized in that, The preparation steps of star anise extract are as follows: S1. Take dried star anise and fennel, crush them respectively with a high-speed crusher, pass through a 40-mesh sieve, remove the fibrous part, and retain the uniform powder crude product; S2. Mix the two crude products with ethanol at a solid-liquid ratio of 1:8, soak them cold for 24 hours, and stir once every 6 hours; and perform ultrasonic treatment with an ultrasonic instrument. The power of the ultrasonic instrument is 300W, the temperature is 30°C, and the extraction time is 40 min; filter the filtrate, collect the filtrate, and re-soak and ultrasonically extract the filter residue at a solid-liquid ratio of 1:4, and combine the two filtrates; S3. Concentrate the combined filtrate to an extract, and vacuum dry it to obtain star anise extract.

3. An antibacterial agent of star anise extract for preventing and treating bacterial wilt and Verticillium wilt as described in claim 1, characterized in that, The preparation method of the star anise extract bacteriostatic agent is: mix the formulated amount of star anise extract and acetone under ultrasonic conditions. The ultrasonic conditions are 240W, the temperature is 25°C, and the time is 30 min; then add Tween 80 and water, and stir evenly to obtain it.

4. The star anise extract bacteriostatic agent for preventing and treating bacterial wilt and Verticillium wilt according to claim 1, characterized in that, The mass ratio of star anise to fennel in the raw material of star anise extract is preferably 2:

1.

5. An antibacterial agent of star anise extract for preventing and treating bacterial wilt and Verticillium wilt as described in claim 1, characterized in that, In step S1, the crude product powder is also pretreated by hydroxyl activation and then subjected to an esterification reaction.

6. The anise extract bacteriostatic agent for preventing and treating bacterial wilt and Verticillium wilt according to claim 5, characterized in that, The specific hydroxyl activation pretreatment is: mix fennel powder with 5% NaOH solution at a solid-liquid ratio of 1:10, react at 60°C for 2 hours; filter, wash with water until neutral, and dry to obtain hydroxylated anethole.

7. An antibacterial agent of star anise extract for preventing and treating bacterial wilt and Verticillium wilt according to claim 6, characterized in that, The specific esterification reaction is: mix hydroxylated anethole and shikimic acid in a molar ratio of 1:1.2, add 1% w / w concentrated sulfuric acid and toluene, reflux at 80°C for 6 hours. After the reaction is completed, cool to room temperature, neutralize with saturated NaHCO3 solution, separate and extract, and collect the organic phase; remove toluene by vacuum distillation to obtain the crude conjugate ester product.

8. An antibacterial agent of star anise extract for preventing and controlling bacterial wilt and Verticillium wilt, as described in claim 7, characterized in that, 10% of anethole based on the total content is added to the crude conjugate ester product.

9. An antibacterial agent of star anise extract for preventing and controlling bacterial wilt and Verticillium wilt as claimed in claim 8, characterized in that, Illicium religiosum is subjected to solidification treatment in the conjugate ester.

10. An antibacterial agent of star anise extract for preventing and treating bacterial wilt and Verticillium wilt as described in claim 9, characterized in that, The specific solidification process is: mix the conjugate ester and anethole in a mass ratio of 9:1, dissolve them in an acetone-water mixed solvent, and magnetically stir until completely dissolved to form a homogeneous solution. Slowly add deionized water to the solution at a rate of 1 mL / min until the water content reaches 40%; perform ultrasonic homogenization treatment; Adjust the pH of the solution to 5.5 - 6.0 with citric acid-phosphate buffer solution, stand at 4°C for 12 h, place the solution in a rotary evaporator and concentrate it under reduced pressure to 10% of the original volume. Freeze-dry to obtain the solidified conjugate ester and anethole mixture.

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