A broad-spectrum bactericide containing natural plant extracts

Abstract

This invention relates to a broad-spectrum fungicide containing natural plant extracts, belonging to the field of pesticide fungicide technology. It comprises the following raw materials in parts by weight: 20-30 parts of plant extract complex nanocrystals, 4-6 parts of nanocrystal stabilizer, 15-25 parts of cosolvent, and 50-60 parts of deionized water. This broad-spectrum fungicide containing natural plant extracts exhibits good broad-spectrum fungicidal activity, significant and stable fungicidal effect, and is safe to use.

Description

Technical Field

[0001] This invention relates to the field of pesticide fungicide technology, and in particular to a broad-spectrum fungicide containing natural plant extracts. Background Technology

[0002] In agricultural production, crop diseases have always been a significant factor affecting yield and quality. While traditional chemical fungicides have good bactericidal effects, long-term use can easily lead to drug resistance in pathogens, and also pollute the environment and agricultural products, endangering human health. It is under these circumstances that broad-spectrum fungicides containing natural plant extracts have emerged, attracting widespread attention within the industry.

[0003] The bactericidal active ingredients in natural plant extracts (such as berberine and emodin) generally suffer from poor water solubility, low photothermal stability, and insufficient transmembrane permeation efficiency. This results in existing fungicides containing natural plant extracts having a narrow spectrum of activity and unstable bactericidal effects, making it difficult to meet the needs of agricultural production for the control of various diseases. Furthermore, existing broad-spectrum fungicides containing natural plant extracts often employ simple extraction methods during preparation, leading to low extraction rates of active ingredients and instability of the active components, thus affecting the effectiveness and shelf life of the fungicides.

[0004] To address the aforementioned issues, Chinese invention patent CN100577014C discloses a plant-derived agricultural fungicide and its preparation method. This fungicide is made from raw materials such as the traditional Chinese medicinal herbs Asarum, Curcuma longa, and Sophora flavescens. Its main active ingredients are Asarum volatile oil, curcumin, curcuminone, and matrine. After extraction, the raw materials are combined with various adjuvants to prepare various formulations, including emulsifiable concentrates, microemulsions, water-in-oil emulsions, and soluble liquids. This fungicide exhibits broad-spectrum inhibitory effects against a variety of plant pathogens. This plant-derived agricultural fungicide possesses advantages such as high efficiency, low toxicity, and low susceptibility to pathogen resistance. Field trials have shown that its control effect on American ginseng leaf spot disease is superior to 70% mancozeb, making it an ideal environmentally friendly pesticide. However, its broad-spectrum fungicidal activity and efficacy still require further improvement.

[0005] It is evident that developing a broad-spectrum fungicide containing natural plant extracts with good bactericidal properties, significant and stable bactericidal effects, and safe use meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the agricultural fungicide field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a broad-spectrum bactericide containing natural plant extracts that has good bactericidal properties, significant and stable bactericidal effect, and is safe to use.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is a broad-spectrum bactericide containing natural plant extracts, comprising the following raw materials in parts by weight: 20-30 parts of plant extract complex nanocrystals, 4-6 parts of nanocrystal stabilizer, 15-25 parts of cosolvent, and 50-60 parts of deionized water.

[0008] Preferably, the co-solvent is ethanol.

[0009] Preferably, the nanocrystalline stabilizer is a mixture of chitosan, other plant polysaccharides, and lecithin in a mass ratio of (1-2):(1-2):(0.5-1).

[0010] Preferably, the degree of deacetylation of the chitosan is ≥90%, and the weight-average molecular weight is 10-20 kDa.

[0011] Preferably, the other plant polysaccharides are at least one of ginkgo leaf polysaccharide, seaweed polysaccharide, laver polysaccharide, and Ganoderma lucidum polysaccharide.

[0012] Preferably, the preparation method of the plant extract complex nanocrystals includes the following steps:

[0013] Step S1, Extraction of plant extract complex: Mix the plant raw materials to obtain a mixture, add citrate buffer (pH=4.5) and complex enzyme, enzymatically hydrolyze for 2-4 hours, centrifuge for 15-25 minutes, and collect the supernatant; extract the precipitate with ethanol; combine the supernatant and the centrifuged solution obtained after ethanol extraction, filter through 0.25μm microfiltration, and concentrate under reduced pressure to a relative density of 1.15 at 25℃ to obtain crude extract concentrate;

[0014] Step S2, Preparation of plant extract complex nanocrystals: The crude extract concentrate prepared in step S1 is uniformly dispersed in a mixed solvent, lecithin is added, and the mixture is sonicated for 13-18 minutes to obtain an oil phase; chitosan solution and trehalose solution are mixed, and nitrogen gas is purged for 8-12 minutes to remove dissolved oxygen, resulting in an aqueous phase; under constant temperature of 25℃ and mechanical stirring, the oil phase is added dropwise to the aqueous phase at a rate of 2 mL / min, and stirring is continued for 25-35 minutes after the addition is complete to form a primary nanocrystal suspension; the primary suspension is circulated 5-8 times using a high-pressure homogenizer at 100-130 MPa, and then filtered through a 0.22 μm filter membrane to obtain a nanocrystal suspension;

[0015] Step S3, Surface modification: The ethanol solution of trimethoxysilane was slowly added dropwise to the nanocrystal suspension at 48-52℃ under nitrogen protection, while maintaining the pH at 8.0-8.5 with ammonia. After the addition was complete, the reaction continued for 1-2 hours. After centrifugation, the nanocrystals of the plant extract complex were obtained by freeze drying.

[0016] Preferably, the plant raw materials in step S1 include the following components by weight: 8-10 parts Coptis chinensis, 6-8 parts Phellodendron chinense, 2-4 parts Rheum palmatum, 1-3 parts Scutellaria baicalensis, 3-5 parts Lonicera japonica, 1-2 parts Mentha haplocalyx, 4-6 parts Sophora flavescens, 3-5 parts Ginkgo biloba, 2-4 parts Rosemary, 1-3 parts Garlic, 2-4 parts Pine needles, 2-4 parts Eucommia ulmoides, and 1-3 parts Artemisia annua.

[0017] Preferably, the mass ratio of the mixture, citrate buffer, and complex enzyme in step S1 is 1:9:(0.03-0.05).

[0018] Preferably, the complex enzyme in step S1 is a mixture of cellulase EC 3.2.1.4 and pectinase EC 3.2.1.15 in a mass ratio of (1-2):1.

[0019] Preferably, the mass ratio of the precipitate to ethanol in step S1 is 1:(6-10).

[0020] Preferably, the ethanol extraction in step S1 is a heating reflux extraction, extracted twice, each time for 1-2 hours, and the two extracts are combined.

[0021] Preferably, the mixed solvent in step S2 is a mixture of ethyl acetate and ethanol in a volume ratio of 3:1.

[0022] Preferably, the mass ratio of the crude extract concentrate, mixed solvent, and lecithin in step S2 is (25-30):100:0.5.

[0023] Preferably, the method for preparing the chitosan solution in step S2 includes the following steps: dissolving chitosan in an aqueous acetic acid solution, stirring magnetically until completely dissolved, and then adjusting the pH to 5.5±0.1 with a 1 mol / L NaOH solution.

[0024] Preferably, the ratio of chitosan to acetic acid aqueous solution is (1-2) g / 100 mL; and the volume percentage concentration of acetic acid aqueous solution is 0.5%.

[0025] Preferably, the ratio of trehalose to water in the trehalose solution in step S2 is (4-5) g / 50 mL.

[0026] Preferably, the mass ratio of chitosan to trehalose in the aqueous phase in step S2 is 0.3:1.

[0027] Preferably, the volume ratio of the aqueous phase to the oil phase in step S2 is 5:1.

[0028] Preferably, in step S3, the volume ratio of trimethoxysilane to ethanol in the trimethoxysilane ethanol solution is 1:(8-10).

[0029] Preferably, the mass ratio of the trimethoxysilane ethanol solution to the nanocrystalline suspension in step S3 is (0.4-0.6):100.

[0030] Another objective of this invention is to provide a method for preparing the broad-spectrum bactericide containing natural plant extracts, comprising the following steps: mixing each raw material evenly according to the weight proportions, sterilizing, and obtaining the broad-spectrum bactericide containing natural plant extracts.

[0031] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0032] (1) The preparation method of the broad-spectrum bactericide containing natural plant extracts disclosed in this invention is simple and easy to implement, convenient to operate and control, has high preparation efficiency and finished product qualification rate, low dependence on equipment, easy to large-scale industrial production, and has high promotion and application value.

[0033] (2) The broad-spectrum bactericide containing natural plant extracts disclosed in this invention comprises the following raw materials in parts by weight: 20-30 parts of plant extract complex nanocrystals, 4-6 parts of nanocrystal stabilizer, 15-25 parts of cosolvent, and 50-60 parts of deionized water. Through the synergistic effect between the raw materials, the resulting bactericide product exhibits broad-spectrum bactericidal activity, significant and stable bactericidal effect, and is safe to use.

[0034] (3) The broad-spectrum bactericide containing natural plant extracts disclosed in this invention comprises the following components by weight: 8-10 parts Coptis chinensis, 6-8 parts Phellodendron chinense, 2-4 parts Rheum palmatum, 1-3 parts Scutellaria baicalensis, 3-5 parts Lonicera japonica, 1-2 parts Mentha haplocalyx, 4-6 parts Sophora flavescens, 3-5 parts Ginkgo biloba, 2-4 parts Rosemary, 1-3 parts Garlic, 2-4 parts Pine needles, 2-4 parts Eucommia ulmoides, and 1-3 parts Artemisia annua. Through the rational selection of the types and amounts of each plant ingredient, they can effectively exert a synergistic effect, and under their combined action, the bactericidal effect and bactericidal stability can be improved, thereby enhancing the broad-spectrum bactericidal activity.

[0035] (4) The broad-spectrum bactericide containing natural plant extracts disclosed in this invention introduces bactericidal active ingredients in the form of plant extract complex nanocrystals. By combining the characteristics of nanomaterials with the biocompatibility of organic components, it has high specific surface area and strong adsorption, targeted action and continuous release, and multiple bactericidal mechanisms working together to effectively improve the broad spectrum and bactericidal effect, resulting in better bactericidal stability. It shows significant advantages in terms of efficiency, safety, stability and application, and provides a new direction for solving the problems of drug resistance, toxicity and environmental problems of traditional bactericides.

[0036] (5) The broad-spectrum bactericide containing natural plant extracts disclosed in this invention, through the reasonable selection of process parameters in the preparation method of plant extract complex nanocrystals, makes the prepared nanocrystals have higher bactericidal activity, better stability and rain washability, and significant control effect on pests and diseases. Detailed Implementation

[0037] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0038] Example 1

[0039] A broad-spectrum bactericide containing natural plant extracts comprises the following raw materials in parts by weight: 20 parts of plant extract complex nanocrystals, 4 parts of nanocrystal stabilizer, 15 parts of cosolvent, and 50 parts of deionized water.

[0040] The cosolvent is ethanol; the nanocrystalline stabilizer is a mixture of chitosan, other plant polysaccharides, and lecithin in a mass ratio of 1:1:0.5; the degree of deacetylation of the chitosan is ≥90%, and the weight-average molecular weight is 10 kDa; the other plant polysaccharides are ginkgo leaf polysaccharides.

[0041] The preparation method of the plant extract complex nanocrystals includes the following steps:

[0042] Step S1, Extraction of plant extract complex: Mix the plant raw materials to obtain a mixture, add citrate buffer (pH=4.5) and complex enzyme, enzymatically hydrolyze for 2 hours, centrifuge for 15 minutes, and collect the supernatant; extract the precipitate with ethanol; combine the supernatant and the centrifuged solution obtained after ethanol extraction, filter through 0.25μm microfiltration, and concentrate under reduced pressure to a relative density of 1.15 at 25℃ to obtain crude extract concentrate;

[0043] Step S2, Preparation of plant extract complex nanocrystals: The crude extract concentrate prepared in step S1 is uniformly dispersed in a mixed solvent, lecithin is added, and the mixture is sonicated for 13 minutes to obtain an oil phase; chitosan solution and trehalose solution are mixed, and nitrogen gas is purged for 8 minutes to remove dissolved oxygen to obtain an aqueous phase; under constant temperature of 25℃ and mechanical stirring, the oil phase is added dropwise to the aqueous phase at a rate of 2 mL / min, and stirring is continued for 25 minutes after the addition is completed to form a primary nanocrystal suspension; the primary suspension is circulated 5 times under high pressure homogenizer at 100 MPa, and filtered through a 0.22 μm filter membrane to obtain a nanocrystal suspension;

[0044] Step S3, Surface modification: The ethanol solution of trimethoxysilane was slowly added dropwise to the nanocrystal suspension at 48°C under nitrogen protection, while maintaining the pH at 8.0 with ammonia. After the addition was complete, the reaction continued for 1 hour. After centrifugation, the nanocrystals of the plant extract complex were obtained by freeze drying.

[0045] The plant raw materials mentioned in step S1 include the following components by weight: 8 parts Coptis chinensis, 6 parts Phellodendron chinense, 2 parts Rheum palmatum, 1 part Scutellaria baicalensis, 3 parts Lonicera japonica, 1 part Mentha haplocalyx, 4 parts Sophora flavescens, 3 parts Ginkgo biloba, 2 parts Rosemary, 1 part Garlic, 2 parts Pine needles, 2 parts Eucommia ulmoides, and 1 part Artemisia annua; the mass ratio of the mixture, citrate buffer, and compound enzyme in step S1 is 1:9:0.03; the compound enzyme in step S1 is a mixture of cellulase EC 3.2.1.4 and pectinase EC 3.2.1.15 in a mass ratio of 1:1; the mass ratio of the precipitate and ethanol in step S1 is 1:6; the ethanol extraction in step S1 is a heating reflux extraction, extracted twice, 1 hour each time, and the two extracts are combined.

[0046] The mixed solvent in step S2 is a mixture of ethyl acetate and ethanol in a volume ratio of 3:1; the mass ratio of the crude extract concentrate, mixed solvent, and lecithin in step S2 is 25:100:0.5; the preparation method of the chitosan solution in step S2 includes the following steps: dissolving chitosan in an aqueous acetic acid solution, stirring magnetically until completely dissolved, and then adjusting the pH to 5.5±0.1 with a 1 mol / L NaOH solution; the mass ratio of chitosan to the aqueous acetic acid solution is 1 g / 100 mL; The volume percentage concentration of the acetic acid aqueous solution is 0.5%; the ratio of trehalose to water in the trehalose solution in step S2 is 4 g / 50 mL; the mass ratio of chitosan to trehalose in the aqueous phase in step S2 is 0.3:1; the volume ratio of the aqueous phase to the oil phase in step S2 is 5:1; the volume ratio of trimethoxysilane to ethanol in the trimethoxysilane ethanol solution in step S3 is 1:8; the mass ratio of the trimethoxysilane ethanol solution to the nanocrystalline suspension in step S3 is 0.4:100.

[0047] A method for preparing a broad-spectrum bactericide containing natural plant extracts includes the following steps: mixing each raw material evenly according to the weight parts, sterilizing, and obtaining a broad-spectrum bactericide containing natural plant extracts.

[0048] Example 2

[0049] A broad-spectrum bactericide containing natural plant extracts comprises the following raw materials in parts by weight: 23 parts plant extract complex nanocrystals, 4.5 parts nanocrystal stabilizer, 17 parts cosolvent, and 53 parts deionized water.

[0050] The cosolvent is ethanol; the nanocrystalline stabilizer is a mixture of chitosan, other plant polysaccharides, and lecithin in a mass ratio of 1.2:1.3:0.6; the degree of deacetylation of the chitosan is ≥90%, and the weight-average molecular weight is 13kDa; the other plant polysaccharides are seaweed polysaccharides.

[0051] The preparation method of the plant extract complex nanocrystals includes the following steps:

[0052] Step S1, Extraction of plant extract complex: Mix the plant raw materials to obtain a mixture, add citrate buffer (pH=4.5) and complex enzyme, enzymatically hydrolyze for 2.5 hours, centrifuge for 17 minutes, and collect the supernatant; extract the precipitate with ethanol; combine the supernatant and the centrifuged solutions obtained after ethanol extraction, filter through 0.25 μm microfiltration, and concentrate under reduced pressure to a relative density of 1.15 at 25℃ to obtain a crude extract concentrate;

[0053] Step S2, Preparation of plant extract complex nanocrystals: The crude extract concentrate prepared in step S1 was uniformly dispersed in a mixed solvent, lecithin was added, and the mixture was sonicated for 14 minutes to obtain an oil phase; chitosan solution and trehalose solution were mixed, and nitrogen gas was purged for 9 minutes to remove dissolved oxygen to obtain an aqueous phase; under constant temperature of 25℃ and mechanical stirring, the oil phase was added dropwise to the aqueous phase at a rate of 2 mL / min, and stirring was continued for 27 minutes after the addition was completed to form a primary nanocrystal suspension; the primary suspension was circulated 6 times under high pressure homogenizer at 110 MPa, and filtered through a 0.22 μm filter membrane to obtain a nanocrystal suspension;

[0054] Step S3, Surface modification: The ethanol solution of trimethoxysilane was slowly added dropwise to the nanocrystal suspension at 49°C under nitrogen protection, while maintaining the pH at 8.1 with ammonia. After the addition was complete, the reaction continued for 1.2 hours. After centrifugation, the nanocrystals of the plant extract complex were obtained by freeze drying.

[0055] The plant materials mentioned in step S1 include the following components by weight: 8.5 parts Coptis chinensis, 6.5 parts Phellodendron chinense, 2.5 parts Rheum palmatum, 1.5 parts Scutellaria baicalensis, 3.5 parts Lonicera japonica, 1.2 parts Mentha haplocalyx, 4.5 parts Sophora flavescens, 3.5 parts Ginkgo biloba, 2.5 parts Rosemary, 1.5 parts Garlic, 2.5 parts Pine needles, 2.5 parts Eucommia ulmoides, and 1.5 parts Artemisia annua; the mass ratio of the mixture, citrate buffer, and compound enzyme in step S1 is 1:9:0.035; the compound enzyme in step S1 is cellulase EC. 3.2.1.4 and pectinase EC 3.2.1.15 are mixed at a mass ratio of 1.3:1; the mass ratio of the precipitate and ethanol in step S1 is 1:7; the ethanol extraction in step S1 is a heating reflux extraction, extracted twice, each time for 1.2 hours, and the two extracts are combined; the mixed solvent in step S2 is a mixture of ethyl acetate and ethanol at a volume ratio of 3:1; the mass ratio of the crude extract concentrate, mixed solvent, and lecithin in step S2 is 27:100:0.5.

[0056] The preparation method of the chitosan solution in step S2 includes the following steps: dissolving chitosan in an aqueous acetic acid solution, stirring magnetically until completely dissolved, and then adjusting the pH to 5.5±0.1 with 1 mol / L NaOH solution; the molar ratio of chitosan to aqueous acetic acid solution is 1.3 g / 100 mL; the volume percentage concentration of the aqueous acetic acid solution is 0.5%; the molar ratio of trehalose to water in the trehalose solution in step S2 is 4.3 g / 50 mL; the mass ratio of chitosan to trehalose in the aqueous phase in step S2 is 0.3:1; the volume ratio of the aqueous phase to the oil phase in step S2 is 5:1; the volume ratio of trimethoxysilane to ethanol in the trimethoxysilane ethanol solution in step S3 is 1:8.5; the mass ratio of the trimethoxysilane ethanol solution to the nanocrystalline suspension in step S3 is 0.45:100.

[0057] A method for preparing a broad-spectrum bactericide containing natural plant extracts includes the following steps: mixing each raw material evenly according to the weight parts, sterilizing, and obtaining a broad-spectrum bactericide containing natural plant extracts.

[0058] Example 3

[0059] A broad-spectrum bactericide containing natural plant extracts comprises the following raw materials in parts by weight: 25 parts of plant extract complex nanocrystals, 5 parts of nanocrystal stabilizer, 20 parts of cosolvent, and 55 parts of deionized water.

[0060] The cosolvent is ethanol; the nanocrystalline stabilizer is a mixture of chitosan, other plant polysaccharides, and lecithin in a mass ratio of 1.5:1.5:0.8; the chitosan has a degree of deacetylation ≥90% and a weight-average molecular weight of 15 kDa; the other plant polysaccharides are laver polysaccharides.

[0061] The preparation method of the plant extract complex nanocrystals includes the following steps:

[0062] Step S1: Extraction of plant extract complex: Mix the plant raw materials to obtain a mixture, add citrate buffer (pH=4.5) and complex enzyme, enzymatically hydrolyze for 3 hours, centrifuge for 20 minutes, and collect the supernatant; extract the precipitate with ethanol; combine the supernatant and the centrifuged solutions obtained after ethanol extraction, filter through 0.25 μm microfiltration, and concentrate under reduced pressure to a relative density of 1.15 at 25℃ to obtain crude extract concentrate;

[0063] Step S2, Preparation of plant extract complex nanocrystals: The crude extract concentrate prepared in step S1 is uniformly dispersed in a mixed solvent, lecithin is added, and the mixture is sonicated for 15 minutes to obtain an oil phase; chitosan solution and trehalose solution are mixed, and nitrogen gas is purged for 10 minutes to remove dissolved oxygen to obtain an aqueous phase; under constant temperature of 25℃ and mechanical stirring, the oil phase is added dropwise to the aqueous phase at a rate of 2 mL / min, and stirring is continued for 30 minutes after the addition is completed to form a primary nanocrystal suspension; the primary suspension is circulated 7 times using a high-pressure homogenizer at 115 MPa, and filtered through a 0.22 μm filter membrane to obtain a nanocrystal suspension;

[0064] Step S3, Surface modification: The ethanol solution of trimethoxysilane was slowly added dropwise to the nanocrystal suspension at 50°C under nitrogen protection, while maintaining the pH at 8.3 with ammonia. After the addition was complete, the reaction continued for 1.5 hours. After centrifugation, the nanocrystals of the plant extract complex were obtained by freeze drying.

[0065] The plant materials mentioned in step S1 include the following components by weight: 9 parts Coptis chinensis, 7 parts Phellodendron chinense, 3 parts Rheum palmatum, 2 parts Scutellaria baicalensis, 4 parts Lonicera japonica, 1.5 parts Mentha haplocalyx, 5 parts Sophora flavescens, 4 parts Ginkgo biloba, 3 parts Rosemary, 2 parts Garlic, 3 parts Pine needles, 3 parts Eucommia ulmoides, and 2 parts Artemisia annua; the mass ratio of the mixture, citrate buffer, and compound enzyme in step S1 is 1:9:0.04; the compound enzyme in step S1 is cellulase EC 3.2.1.4 and pectinase EC. 3.2.1.15 is prepared by mixing in a mass ratio of 1.5:1; the mass ratio of the precipitate and ethanol in step S1 is 1:8; the ethanol extraction in step S1 is a heating reflux extraction, extracted twice, each time for 1.5 hours, and the two extracts are combined; the mixed solvent in step S2 is a mixture of ethyl acetate and ethanol in a volume ratio of 3:1; the mass ratio of the crude extract concentrate, mixed solvent, and lecithin in step S2 is 28:100:0.5.

[0066] The preparation method of the chitosan solution in step S2 includes the following steps: dissolving chitosan in an aqueous acetic acid solution, stirring magnetically until completely dissolved, and then adjusting the pH to 5.5±0.1 with 1 mol / L NaOH solution; the molar ratio of chitosan to aqueous acetic acid solution is 1.5 g / 100 mL; the volume percentage concentration of the aqueous acetic acid solution is 0.5%; the molar ratio of trehalose to water in the trehalose solution in step S2 is 4.5 g / 50 mL; the mass ratio of chitosan to trehalose in the aqueous phase in step S2 is 0.3:1; the volume ratio of the aqueous phase to the oil phase in step S2 is 5:1; the volume ratio of trimethoxysilane to ethanol in the trimethoxysilane ethanol solution in step S3 is 1:9; the mass ratio of the trimethoxysilane ethanol solution to the nanocrystalline suspension in step S3 is 0.5:100.

[0067] A method for preparing a broad-spectrum bactericide containing natural plant extracts includes the following steps: mixing each raw material evenly according to the weight parts, sterilizing, and obtaining a broad-spectrum bactericide containing natural plant extracts.

[0068] Example 4

[0069] A broad-spectrum bactericide containing natural plant extracts comprises the following raw materials in parts by weight: 28 parts of plant extract complex nanocrystals, 5.5 parts of nanocrystal stabilizer, 23 parts of cosolvent, and 58 parts of deionized water.

[0070] The cosolvent is ethanol; the nanocrystalline stabilizer is a mixture of chitosan, other plant polysaccharides, and lecithin in a mass ratio of 1.8:1.8:0.9; the degree of deacetylation of the chitosan is ≥90%, and the weight-average molecular weight is 18kDa; the other plant polysaccharides are a mixture of ginkgo leaf polysaccharide, seaweed polysaccharide, laver polysaccharide, and Ganoderma lucidum polysaccharide in a mass ratio of 1:2:2:1.

[0071] The preparation method of the plant extract complex nanocrystals includes the following steps:

[0072] Step S1, Extraction of plant extract complex: The plant raw materials were mixed to obtain a mixture, and citrate buffer (pH=4.5) and a complex enzyme were added. The mixture was enzymatically hydrolyzed for 3.5 hours, centrifuged for 23 minutes, and the supernatant was collected. The precipitate was extracted with ethanol. The supernatant and the liquid obtained after centrifugation after ethanol extraction were combined, filtered through a 0.25 μm filter, and concentrated under reduced pressure to a relative density of 1.15 at 25°C to obtain a crude extract concentrate.

[0073] Step S2, Preparation of plant extract complex nanocrystals: The crude extract concentrate prepared in step S1 was uniformly dispersed in a mixed solvent, lecithin was added, and the mixture was sonicated for 17 minutes to obtain an oil phase; chitosan solution and trehalose solution were mixed, and nitrogen gas was purged for 11 minutes to remove dissolved oxygen to obtain an aqueous phase; under constant temperature of 25℃ and mechanical stirring, the oil phase was added dropwise to the aqueous phase at a rate of 2 mL / min, and stirring was continued for 33 minutes after the addition was completed to form a primary nanocrystal suspension; the primary suspension was circulated 7 times under high pressure homogenizer at 125 MPa, and filtered through a 0.22 μm filter membrane to obtain a nanocrystal suspension;

[0074] Step S3, Surface modification: The ethanol solution of trimethoxysilane was slowly added dropwise to the nanocrystal suspension at 51°C under nitrogen protection, while maintaining the pH at 8.4 with ammonia. After the addition was complete, the reaction continued for 1.9 hours. After centrifugation, the nanocrystals of the plant extract complex were obtained by freeze drying.

[0075] The plant materials mentioned in step S1 include the following components by weight: Coptis chinensis 9.5 parts, Phellodendron chinense 7.5 parts, Rheum palmatum 3.5 parts, Scutellaria baicalensis 2.5 parts, Lonicera japonica 4.5 parts, Mentha haplocalyx 1.9 parts, Sophora flavescens 5.5 parts, Ginkgo biloba 4.5 parts, Rosemary 3.5 parts, Garlic 2.5 parts, Pine needles 3.5 parts, Eucommia ulmoides 3.5 parts, and Artemisia annua 2.5 parts; the mass ratio of the mixture, citrate buffer, and compound enzyme in step S1 is 1:9:0.045; the compound enzyme in step S1 is cellulase EC. 3.2.1.4 and pectinase EC 3.2.1.15 are mixed at a mass ratio of 1.9:1; the mass ratio of the precipitate and ethanol in step S1 is 1:9.5; the ethanol extraction in step S1 is a heating reflux extraction, extracted twice, each time for 1.9 hours, and the two extracts are combined; the mixed solvent in step S2 is ethyl acetate and ethanol mixed at a volume ratio of 3:1; the mass ratio of the crude extract concentrate, mixed solvent, and lecithin in step S2 is 29:100:0.5.

[0076] The preparation method of the chitosan solution in step S2 includes the following steps: dissolving chitosan in an aqueous acetic acid solution, stirring magnetically until completely dissolved, and then adjusting the pH to 5.5±0.1 with 1 mol / L NaOH solution; the molar ratio of chitosan to aqueous acetic acid solution is 1.9 g / 100 mL; the volume percentage concentration of the aqueous acetic acid solution is 0.5%; the molar ratio of trehalose to water in the trehalose solution in step S2 is 4.8 g / 50 mL; the mass ratio of chitosan to trehalose in the aqueous phase in step S2 is 0.3:1; the volume ratio of the aqueous phase to the oil phase in step S2 is 5:1; the volume ratio of trimethoxysilane to ethanol in the trimethoxysilane ethanol solution in step S3 is 1:9.5; the mass ratio of the trimethoxysilane ethanol solution to the nanocrystalline suspension in step S3 is 0.55:100.

[0077] A method for preparing a broad-spectrum bactericide containing natural plant extracts includes the following steps: mixing each raw material evenly according to the weight parts, sterilizing, and obtaining a broad-spectrum bactericide containing natural plant extracts.

[0078] Example 5

[0079] A broad-spectrum bactericide containing natural plant extracts comprises the following raw materials in parts by weight: 30 parts of plant extract complex nanocrystals, 6 parts of nanocrystal stabilizer, 25 parts of cosolvent, and 60 parts of deionized water.

[0080] The cosolvent is ethanol; the nanocrystalline stabilizer is a mixture of chitosan, other plant polysaccharides, and lecithin in a mass ratio of 2:2:1; the degree of deacetylation of the chitosan is ≥90%, and the weight-average molecular weight is 20kDa; the other plant polysaccharides are Ganoderma lucidum polysaccharides.

[0081] The preparation method of the plant extract complex nanocrystals includes the following steps:

[0082] Step S1, Extraction of plant extract complex: Mix the plant raw materials to obtain a mixture, add citrate buffer (pH=4.5) and complex enzyme, enzymatically hydrolyze for 4 hours, centrifuge for 25 minutes, and collect the supernatant; extract the precipitate with ethanol; combine the supernatant and the liquid obtained by centrifugation after ethanol extraction, filter through 0.25μm microfiltration, and concentrate under reduced pressure to a relative density of 1.15 at 25℃ to obtain crude extract concentrate;

[0083] Step S2, Preparation of plant extract complex nanocrystals: The crude extract concentrate prepared in step S1 is uniformly dispersed in a mixed solvent, lecithin is added, and the mixture is sonicated for 18 minutes to obtain an oil phase; chitosan solution and trehalose solution are mixed, and nitrogen gas is purged for 12 minutes to remove dissolved oxygen to obtain an aqueous phase; under constant temperature of 25℃ and mechanical stirring, the oil phase is added dropwise to the aqueous phase at a rate of 2 mL / min, and stirring is continued for 35 minutes after the addition is completed to form a primary nanocrystal suspension; the primary suspension is circulated 8 times under high pressure homogenizer at 130 MPa, and filtered through a 0.22 μm filter membrane to obtain a nanocrystal suspension;

[0084] Step S3, Surface modification: The ethanol solution of trimethoxysilane was slowly added dropwise to the nanocrystal suspension at 52°C under nitrogen protection, while maintaining the pH at 8.5 with ammonia. After the addition was complete, the reaction continued for 2 hours. After centrifugation, the nanocrystals of the plant extract complex were obtained by freeze drying.

[0085] The plant materials mentioned in step S1 include the following components by weight: 10 parts Coptis chinensis, 8 parts Phellodendron chinense, 4 parts Rheum palmatum, 3 parts Scutellaria baicalensis, 5 parts Lonicera japonica, 2 parts Mentha haplocalyx, 6 parts Sophora flavescens, 5 parts Ginkgo biloba leaves, 4 parts Rosemary, 3 parts Garlic, 4 parts Pine needles, 4 parts Eucommia ulmoides, and 3 parts Artemisia annua; the mass ratio of the mixture, citrate buffer, and compound enzyme in step S1 is 1:9:0.05; the compound enzyme in step S1 is cellulase EC 3.2.1.4 and pectinase EC. 3.2.1.15 is prepared by mixing at a mass ratio of 2:1; the mass ratio of the precipitate and ethanol in step S1 is 1:10; the ethanol extraction in step S1 is a heating reflux extraction, extracted twice, 2 hours each time, and the two extracts are combined; the mixed solvent in step S2 is a mixture of ethyl acetate and ethanol at a volume ratio of 3:1; the mass ratio of the crude extract concentrate, mixed solvent, and lecithin in step S2 is 30:100:0.5.

[0086] The preparation method of the chitosan solution in step S2 includes the following steps: dissolving chitosan in an aqueous acetic acid solution, stirring magnetically until completely dissolved, and then adjusting the pH to 5.5±0.1 with 1 mol / L NaOH solution; the molar ratio of chitosan to aqueous acetic acid solution is 2 g / 100 mL; the volume percentage concentration of the aqueous acetic acid solution is 0.5%; the molar ratio of trehalose to water in the trehalose solution in step S2 is 5 g / 50 mL; the mass ratio of chitosan to trehalose in the aqueous phase in step S2 is 0.3:1; the volume ratio of the aqueous phase to the oil phase in step S2 is 5:1; the volume ratio of trimethoxysilane to ethanol in the trimethoxysilane ethanol solution in step S3 is 1:10; the mass ratio of the trimethoxysilane ethanol solution to the nanocrystalline suspension in step S3 is 0.6:100.

[0087] A method for preparing a broad-spectrum bactericide containing natural plant extracts includes the following steps: mixing each raw material evenly according to the weight parts, sterilizing, and obtaining a broad-spectrum bactericide containing natural plant extracts.

[0088] Comparative Example 1

[0089] A broad-spectrum bactericide containing natural plant extracts and its preparation method are basically the same as those in Example 1, except that an equal amount of crude extract concentrate is used instead of plant extract complex nanocrystals.

[0090] Comparative Example 2

[0091] A broad-spectrum bactericide containing natural plant extracts and its preparation method are basically the same as those in Example 1, except that step S3 and surface modification are omitted, the nanocrystalline suspension is directly centrifuged and then freeze-dried, and no pine needles and artemisia are added.

[0092] To further illustrate the beneficial technical effects of the broad-spectrum fungicides containing natural plant extracts involved in the various embodiments of the present invention, relevant performance tests were conducted on the broad-spectrum fungicides containing natural plant extracts involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1, and the test methods are as follows:

[0093] (1) Inhibition zone test: Referring to GB / T 38483-2020 Determination of antibacterial activity of secondary metabolites of microbial antibiotics by inhibition zone method, the diameter of the inhibition zone against cucumber wilt fungus, tomato early blight fungus and rice blast fungus was determined by the Oxford cup method.

[0094] (2) Field trial: The trial was conducted at a cucumber planting base. The experimental plots were selected from cucumber fields with flat terrain, uniform fertility, and the same planted varieties. The plots were randomly divided into Example 1-5 and Comparative Example 1-2 groups, with each plot area being 30m². 2 Apply the pesticide evenly to cucumber plants using a backpack sprayer at a dosage of 200g / mu on a windless, sunny morning between 9 and 11 a.m. Investigate the initial disease population of cucumbers before application and reassess the disease index 15 days after application to calculate the relative control effect.

[0095] (3) Rain erosion resistance: The test was conducted using an artificial rainfall simulation device with a simulated rainfall intensity of 10 mm / h and a duration of 30 minutes. Before the rainfall, the nanocrystalline fungicide was evenly sprayed onto the surface of cucumber leaves. After the fungicide dried naturally, simulated rainfall was conducted. After the rainfall, leaf samples were collected, and the residual fungicide on the leaf surface was eluted using a suitable solvent (such as a mixed solution of ethanol and water at a volume ratio of 1:1). The content of active ingredients in the eluent was then determined by HPLC, and the leaf surface residue rate was calculated to reflect the fungicide's resistance to rain erosion.

[0096] Table 1. Performance test results of broad-spectrum bactericides containing natural plant extracts

[0097]

[0098] As can be seen from Table 1, the broad-spectrum bactericide containing natural plant extracts involved in the embodiments of the present invention has better bactericidal effect, better control effect on pests and diseases, and better resistance to rain washout than the comparative product; the combined use of plant extract complex nanocrystals, surface modification, pine needles and artemisia annua is beneficial to improving the above properties.

[0099] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A broad-spectrum bactericide containing natural plant extracts, characterized in that, The product comprises the following raw materials in parts by weight: 20-30 parts of plant extract complex nanocrystals, 4-6 parts of nanocrystal stabilizer, 15-25 parts of cosolvent, and 50-60 parts of deionized water; wherein the nanocrystal stabilizer is a mixture of chitosan, other plant polysaccharides, and lecithin in a mass ratio of (1-2):(1-2):(0.5-1); The preparation method of the plant extract complex nanocrystals includes the following steps: Step S1, Extraction of plant extract complex: The plant raw materials are mixed to obtain a mixture, citrate buffer solution with pH=4.5 and a complex enzyme are added, and the mixture is enzymatically hydrolyzed for 2-4 hours. After centrifugation for 15-25 minutes, the supernatant is collected. The precipitate is extracted with ethanol. The supernatant and the liquid obtained after centrifugation after ethanol extraction are combined, filtered through a 0.25μm microfiltration, and concentrated under reduced pressure to a relative density of 1.15 at 25℃ to obtain a crude extract concentrate. The plant raw materials include the following components in parts by weight: Coptis chinensis 8-10 parts, Phellodendron chinense 6-8 parts, Rheum palmatum 2-4 parts, Scutellaria baicalensis 1-3 parts, Lonicera japonica 3-5 parts, Mentha haplocalyx 1-2 parts, Sophora flavescens 4-6 parts, Ginkgo biloba 3-5 parts, Rosemary 2-4 parts, Garlic 1-3 parts, Pine needles 2-4 parts, Eucommia ulmoides 2-4 parts, Artemisia annua 1-3 parts. Step S2, Preparation of plant extract complex nanocrystals: The crude extract concentrate prepared in step S1 is uniformly dispersed in a mixed solvent, lecithin is added, and the mixture is sonicated for 13-18 minutes to obtain an oil phase; chitosan solution and trehalose solution are mixed, and nitrogen gas is purged for 8-12 minutes to remove dissolved oxygen, resulting in an aqueous phase; under constant temperature of 25℃ and mechanical stirring, the oil phase is added dropwise to the aqueous phase at a rate of 2 mL / min, and stirring is continued for 25-35 minutes after the addition is complete to form a primary nanocrystal suspension; the primary suspension is circulated 5-8 times using a high-pressure homogenizer at 100-130 MPa, and then filtered through a 0.22 μm filter membrane to obtain a nanocrystal suspension; Step S3, Surface modification: The ethanol solution of trimethoxysilane was slowly added dropwise to the nanocrystal suspension at 48-52℃ under nitrogen protection, while maintaining the pH at 8.0-8.5 with ammonia. After the addition was complete, the reaction continued for 1-2 hours. After centrifugation, the nanocrystals of the plant extract complex were obtained by freeze drying.

2. The broad-spectrum bactericide containing natural plant extracts according to claim 1, characterized in that, The co-solvent is ethanol.

3. The broad-spectrum bactericide containing natural plant extracts according to claim 1, characterized in that, The degree of deacetylation of the chitosan is ≥90%, and the weight-average molecular weight is 10-20 kDa; the other plant polysaccharides are at least one of ginkgo leaf polysaccharide, seaweed polysaccharide, laver polysaccharide, and Ganoderma lucidum polysaccharide.

4. The broad-spectrum bactericide containing natural plant extracts according to claim 1, characterized in that, The mass ratio of the mixture, citrate buffer, and complex enzyme in step S1 is 1:9:(0.03-0.05); the complex enzyme in step S1 is cellulase EC. 3.2.1.4 Pectinase EC 3.2.1.15 is mixed at a mass ratio of (1-2):

1.

5. The broad-spectrum bactericide containing natural plant extracts according to claim 1, characterized in that, The mass ratio of precipitate to ethanol in step S1 is 1:(6-10); the ethanol extraction in step S1 is reflux extraction, extracted twice, each time for 1-2 hours, and the two extracts are combined; the mixed solvent in step S2 is ethyl acetate and ethanol mixed in a volume ratio of 3:1; the mass ratio of crude extract concentrate, mixed solvent, and lecithin in step S2 is (25-30):100:0.

5.

6. The broad-spectrum bactericide containing natural plant extracts according to claim 1, characterized in that, The preparation method of the chitosan solution in step S2 includes the following steps: dissolving chitosan in an aqueous acetic acid solution, stirring magnetically until completely dissolved, and then adjusting the pH to 5.5±0.1 with a 1mol / L NaOH solution; the molar ratio of chitosan to aqueous acetic acid solution is (1-2) g / 100mL; the volume percentage concentration of the aqueous acetic acid solution is 0.5%; the molar ratio of trehalose to water in the trehalose solution in step S2 is (4-5) g / 50mL; the mass ratio of chitosan to trehalose in the aqueous phase in step S2 is 0.3:1; and the volume ratio of the aqueous phase to the oil phase in step S2 is 5:

1.

7. The broad-spectrum bactericide containing natural plant extracts according to claim 1, characterized in that, In step S3, the volume ratio of trimethoxysilane to ethanol in the trimethoxysilane ethanol solution is 1:(8-10); the mass ratio of the trimethoxysilane ethanol solution to the nanocrystalline suspension in step S3 is (0.4-0.6):

100.

8. A method for preparing a broad-spectrum bactericide containing natural plant extracts according to any one of claims 1-7, characterized in that, The process includes the following steps: mixing the raw materials evenly according to their weight proportions, sterilizing them, and obtaining a broad-spectrum bactericide containing natural plant extracts.

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