Extracting plant effective components in hypergravity field environment and insect-proof microspheres prepared by the same

Abstract

The present application belongs to the field of tobacco storage and insect prevention, and particularly relates to a preparation method of insect prevention microsphere film by extracting plant effective components in a super gravity field environment. Tobacco is extremely vulnerable to the damage of tobacco storage pests during storage and aging, and it is very important to develop safe and effective insect prevention products. Plants with insecticidal and insect prevention effects are screened, effective components in the plants are extracted by distillation, distillation residues are extracted in a super gravity field environment, and the extracted effective components are used as insect prevention agents. Cyclodextrin microspheres are used as drug release agents, polyvinyl alcohol is used as the main film forming raw material, water is used as the solvent, and film forming plasticizers and toughening agents are added to prepare polyvinyl alcohol drug-loaded microsphere film. The raw material of the present application is easy to obtain, biodegradable, and can reduce environmental pollution, improve the stability of plant effective components, prolong the action time of the drug, and improve the utilization rate of the drug.

Description

Technical Field

[0001] This invention belongs to the field of insect control technology, specifically relating to an effective plant component extracted in a hypergravity environment and an insect-repellent microsphere membrane prepared therefrom. Background Technology

[0002] Tobacco leaves are highly susceptible to pests during storage and aging. In my country, there are over 30 species of tobacco storage pests, including the tobacco beetle, tobacco mealybug, red flour beetle, and large flour beetle, causing significant damage. Currently, many tobacco warehouses of China Tobacco Corporation still rely on chemical control methods. Chemical control in tobacco warehouses primarily involves fumigation, but the pesticides used can easily cause poisoning, spontaneous combustion, and potential explosions. While widely adopted green control technologies such as nitrogen-filled insecticides have limitations, including rudimentary technical parameters, large workloads, and difficulties in humidity control, biological and physical control technologies are mostly still in the experimental stage. Therefore, developing safe and effective pest control technologies and products is crucial.

[0003] Plants possess insecticidal and insect-repellent properties, and extracting these plant components yields extracts with excellent insecticidal and insect-repellent effects. Various methods exist for extracting active plant components, including solvent extraction, ultrasound-assisted extraction, and microwave-assisted extraction. Hypergravity technology is a technique that enhances molecular mixing and mass transfer processes; hypergravity extraction involves extracting active components from plants in a hypergravity field. The hypergravity factor is the ratio of acceleration to gravitational acceleration; the higher the value, the more pronounced the hypergravity phenomenon. Hypergravity extraction methods are rarely reported.

[0004] The preparation of insect-repellent microsphere membranes requires the initial formation of microspheres followed by membrane formation, and the resulting microsphere membrane must successfully load the drug component. Cyclodextrins possess internal hydrophobic cavities and hydrophilic external surfaces, enabling them to form reversible inclusion complexes with various hydrophobic molecules, allowing for the slow release of the guest drug without altering its physical, chemical, and biological properties. Natural polymers are widely available, inexpensive, and have short degradation times, making them suitable as effective drug delivery systems and membrane-forming matrices. Polyvinyl alcohol exhibits good film-forming properties, high tensile strength, and excellent flexibility, and can be blended with other polymers to prepare high-performance composite materials.

[0005] This invention uses cyclodextrin and polyvinyl alcohol as base materials. First, plants with insecticidal and insect-repellent effects are distilled, and then the residue is extracted using a hypergravity environment. The extracted active ingredients are used as drug carriers to prepare a tobacco insect-repellent microsphere membrane system. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a simple, low-cost, and environmentally friendly method for extracting plant active ingredients in a supergravity field environment, as well as an insect-repellent microsphere membrane prepared therefrom.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for extracting effective components from plants in a hypergravity environment involves screening plants with insecticidal and insect-repellent effects, adding water for steam distillation (preferably for 2-10 hours) to obtain a distillate; extracting the plant residue with methanol or ethanol solution at room temperature and pressure in a hypergravity environment with a hypergravity factor of 2-2000 (preferably for 30-180 minutes), collecting the filtrate and concentrating it to obtain a concentrate.

[0009] The distilled extract and / or concentrate are the plant's active ingredients.

[0010] The methanol or ethanol solution refers to pure methanol or ethanol, or a 20-80% methanol / ethanol aqueous solution.

[0011] Specifically, the plant may be selected from one or more of the following: Artemisia argyi, camphor tree, mint, Sichuan pepper, Ailanthus altissima, oleander, and wolfsbane, with camphor tree, mint, and Artemisia argyi being preferred.

[0012] This invention provides plant active ingredients extracted using the above method. In use, the plant active ingredients can be diluted by dissolving them in an organic solvent, including one or more of methanol, acetone, and ethanol (preferably ethanol).

[0013] The present invention also provides the application of the above-mentioned plant active ingredients as insect repellents or in the preparation of insect repellent microspheres.

[0014] The present invention also provides an insect-repellent microsphere film, which uses the plant active ingredients as insect repellent agents, cyclodextrin microspheres as drug-carrying and sustained-release agents, polyvinyl alcohol as the main film-forming material, water as a solvent, and adds film-forming plasticizers and toughening agents. After being dispersed evenly, the film is sprayed or coated and then air-dried to obtain the final product.

[0015] Alternatively, using the plant active ingredients as insecticides and cyclodextrin microspheres as drug-loaded sustained-release agents, the cyclodextrin microspheres are impregnated and loaded with the plant active ingredients to obtain cyclodextrin-loaded microspheres; then, using polyvinyl alcohol as the main film-forming material and water as the solvent, film-forming plasticizers and toughening agents are added, dispersed evenly, and then sprayed or coated to form a film, which is then air-dried to obtain the final product.

[0016] Alternatively, cyclodextrin microspheres can be used as drug-carrying sustained-release agents, polyvinyl alcohol as the main film-forming material, water as the solvent, and film-forming plasticizers and toughening agents can be added. After being dispersed evenly, the film can be sprayed or coated, air-dried, and then the plant active ingredients can be sprayed onto the film to obtain the final product.

[0017] This invention also provides an insect-repellent microsphere membrane, which uses epichlorohydrin as a crosslinking agent. Plant active ingredients and cyclodextrin are dissolved in an alkaline solution and crosslinked at room temperature to form an aqueous phase. The aqueous phase is added dropwise to the oil phase, and the mixture is stirred to obtain an oil-water emulsion. The emulsion is reacted at a constant temperature for a certain period of time (preferably 60-80℃ for 4-8 hours), allowed to stand, the oil phase is poured off, centrifuged, washed, and dried to obtain cyclodextrin-loaded microspheres. Then, polyvinyl alcohol is used as the main film-forming material, water is used as the solvent, and film-forming plasticizers and toughening agents are added. After being dispersed evenly, the film is sprayed or coated to form a film and then air-dried to obtain the final product.

[0018] Specifically, in the aforementioned insect-repellent microsphere membrane, the film-forming plasticizer can be a bio-polysaccharide, and the toughening agent can be glycerol. The bio-polysaccharide can be one or more of sodium alginate, chitosan, starch, cellulose, etc. The mass ratio of polyvinyl alcohol to the film-forming plasticizer bio-polysaccharide and the toughening agent glycerol can be 1:0.2-0.6:2. A membrane solution is prepared by adding polyvinyl alcohol, the film-forming plasticizer, and the toughening agent to water. The amount of cyclodextrin microspheres or cyclodextrin-loaded microspheres added can be 10-30% of the mass of the membrane solution.

[0019] Furthermore, the cyclodextrin microspheres are prepared by reverse emulsion polymerization, specifically by the following method: using epichlorohydrin as a crosslinking agent, cyclodextrin is dissolved in alkaline solution and crosslinked at room temperature to form an aqueous phase. The aqueous phase is added dropwise to the oil phase, and the mixture is stirred at high speed to obtain an oil-water emulsion. The mixture is reacted at a constant temperature for a certain time, allowed to stand, the oil phase is poured off, centrifuged, washed, and dried to obtain the final product.

[0020] The oil phase can be an oil solution containing surfactants such as Tween or Span, and the oil solution can be one of white oil, silicone oil, kerosene, etc. Furthermore, the alkali can be one of sodium hydroxide, potassium hydroxide, etc.

[0021] Furthermore, the cyclodextrin can be one of α, β, or γ-cyclodextrin, with β or γ-cyclodextrin being preferred.

[0022] Furthermore, the preparation of the drug-loaded microspheres can be achieved by impregnating and loading cyclodextrin microspheres in a plant extract solution; alternatively, the plant extract, cyclodextrin, and crosslinking agent can be prepared into an aqueous phase in an alkaline solution, and the drug-loaded microspheres can be obtained by reverse emulsion polymerization.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention extracts active plant components under a hypergravity environment and uses these components as insect repellents to prepare drug-loaded insecticidal microspheres. The insecticidal microspheres of this invention improve the stability of the active plant components, prolong the drug's action time, and utilize readily available raw materials. The drug loaded in the membrane is gradually released as the membrane degrades, reducing environmental pollution and improving drug utilization. Attached Figure Description

[0025] Figure 1 The FTIR images are of the β-cyclodextrin microspheres and β-cyclodextrin prepared in Example 1.

[0026] Figure 2 Optical microscope image (left) and SEM image (right) of the β-cyclodextrin microspheres prepared in Example 3;

[0027] Figure 3 The optical microscope (left) and SEM (right) images of the drug-loaded β-cyclodextrin microspheres / polyvinyl alcohol membrane prepared in Example 2 are shown. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0029] In the following embodiments, unless otherwise specified, all raw materials used are common commercially available products that can be directly purchased or can be prepared using conventional methods in the art.

[0030] Room temperature refers to 25±5℃.

[0031] Unless otherwise specified, methanol or ethanol refers to volume percentage.

[0032] This invention provides a method for preparing drug-loaded microsphere membranes, wherein the cyclodextrin microspheres are prepared using reverse emulsion polymerization.

[0033] Example 1:

[0034] A method for preparing insect-repellent microspheres by extracting plant active ingredients in a hypergravity environment includes the following steps:

[0035] Preferably, 5g of β-cyclodextrin and 3g of NaOH are dissolved in 10g of deionized water, and 6.5 mL of epichlorohydrin is added. The cross-linking reaction is carried out at room temperature for 2 hours to form an aqueous phase.

[0036] Span80:Tween80 = 70:30 (mass ratio, 1.6g). Add Span80 and preheat in a 55℃ water bath for 15min. Add Tween80 and stir at 1000r / min for 25min. Then add 60g of kerosene and continue stirring for 15min to form the oil phase.

[0037] The aqueous phase was slowly added dropwise to the oil phase, and the mixture was stirred for 10 minutes using a high-speed mixer to obtain an oil-water emulsion. The mixture was then stirred magnetically at 600 rpm and reacted at a constant temperature of 65°C for 6 hours. After the reaction was complete, the mixture was allowed to stand for 10 minutes, after which clear stratification occurred. The oil phase was then poured off, and the mixture was centrifuged at 9000 rpm for 5 minutes. The product was first neutralized to neutral with 0.5M dilute hydrochloric acid, then washed sequentially with acetone, anhydrous ethanol, and deionized water, and finally air-dried at room temperature to obtain β-cyclodextrin microspheres synthesized by reverse emulsion polymerization.

[0038] First, 100g of camphor tree leaves were steam-distilled with excess water for 2 hours, followed by standing for 2 hours to obtain an oily distillate. Then, the camphor tree leaf residue after distillation was placed in 500mL of 60% ethanol aqueous solvent and extracted at room temperature and pressure for 60 minutes under a hypergravity environment with a hypergravity factor of 12. The filtrate was collected and concentrated into a paste. The concentrated paste and the distillate are the plant's effective components.

[0039] 0.5g of plant active ingredient was dissolved in 50mL of 20% methanol solution for dilution. 1g of β-cyclodextrin microspheres were directly soaked at room temperature for 24h to load the drug onto the obtained plant active ingredient, thus obtaining β-cyclodextrin drug-loaded microspheres.

[0040] 1g of polyvinyl alcohol, 0.3g of sodium alginate, and 2g of glycerol were added sequentially to 30mL of deionized water and heated at 96℃ for 2 hours with stirring to prepare a membrane solution. β-cyclodextrin-loaded microspheres, accounting for 15% of the membrane solution mass, were uniformly dispersed in 30g of the membrane solution using ultrasound. The solution was then coated onto a polyethylene membrane using a scraping method and allowed to air dry naturally to obtain a polyvinyl alcohol insect-repellent loaded microsphere membrane.

[0041] Figure 1 FTIR spectra of the β-cyclodextrin microspheres and β-cyclodextrin prepared in Example 1 are shown. The two lines in the figure represent the FTIR test curves of the β-cyclodextrin microspheres and β-cyclodextrin, respectively, and the two lines are located at 3417 cm⁻¹. -1 and 3399cm -1 The presence of -OH absorption peaks at various locations indicates that the β-cyclodextrin polymer microspheres still possess the characteristic functional group -OH of the β-cyclodextrin molecule. However, the β-cyclodextrin polymer microspheres exhibit an absorption peak at 3417 cm⁻¹. -1 The decrease in peak area at 2926 cm⁻¹ proves that β-cyclodextrin reacted with the cross-linking agent. -1 and 2922cm -1 The peak at 800-1300 cm⁻¹ corresponds to the stretching vibration of methylene (-CH₂). The absorption peak of the β-cyclodextrin polymer microspheres is broader than that of β-cyclodextrin, indicating that a cross-linking reaction occurred between the β-cyclodextrin molecules and the cross-linking agent, leading to an increase in methylene content. -1The peak at this location is a characteristic absorption peak for ether bonds. The β-cyclodextrin polymer microspheres exhibit a relatively wide absorption peak area at this location, further demonstrating that a cross-linking reaction occurred between β-cyclodextrin and the cross-linking agent.

[0042] Example 2:

[0043] A method for preparing insect-repellent microspheres by extracting plant active ingredients in a hypergravity environment includes the following steps:

[0044] First, 150g of peppermint stems and leaves were steam-distilled with excess water for 3 hours, followed by static separation for 2 hours to obtain an oily distillate. Then, the peppermint stem and leaf residue after distillation was placed in 500 mL of ethanol solvent and extracted at room temperature and pressure for 40 minutes under a hypergravity environment with a hypergravity factor of 280. The filtrate was collected and concentrated into a paste. The concentrated paste and the distillate are the plant's active ingredients.

[0045] Take 0.1g of plant active ingredients, 5g of β-cyclodextrin, and 3g of KOH, add them to 10 mL of water, then add 6.5 mL of epichlorohydrin, and perform a cross-linking reaction at room temperature for 1.5 h to form an aqueous phase.

[0046] Span60:Tween60 = 76:27 (mass ratio, 1.6g). Add Span60 and preheat in a 55℃ water bath for 15min. Add Tween60 and stir at 2000r / min for 15min. Then add 60g of silicone oil and continue stirring for 15min to form the oil phase.

[0047] The aqueous phase was slowly added dropwise to the oil phase, and the mixture was stirred for 10 minutes using a high-speed mixer to obtain an oil-water emulsion. The mixture was then stirred magnetically at 800 rpm and reacted at a constant temperature of 70°C for 6 hours. After the reaction was complete, the mixture was allowed to stand for 10 minutes, after which clear stratification occurred. The oil phase was then poured off, and the mixture was centrifuged at 9000 rpm for 5 minutes. The product was first neutralized to neutral with 0.5M dilute hydrochloric acid, then washed sequentially with acetone, anhydrous ethanol, and deionized water, and finally air-dried at room temperature to obtain β-cyclodextrin-loaded microspheres formed by reverse emulsion polymerization.

[0048] 1g of polyvinyl alcohol, 0.3g of chitosan, and 2g of glycerol were added to 30mL of deionized water and heated at 96℃ for 2h with stirring to prepare a membrane solution. β-cyclodextrin drug-loaded microspheres, accounting for 25% of the membrane solution mass, were uniformly dispersed in 30g of the membrane solution using ultrasound. The membrane was then formed by spraying and air-dried to obtain a polyvinyl alcohol insect-repellent drug-loaded microsphere membrane. Example 3:

[0049] A method for preparing insect-repellent microspheres by extracting plant active ingredients in a hypergravity environment includes the following steps:

[0050] Take 5g of γ-cyclodextrin and 3g of NaOH, dissolve them in 10mL of deionized water, then add 6.5mL of epichlorohydrin, and crosslink at room temperature for 2.5h to form an aqueous phase.

[0051] Span40:Tween40 = 82:7 (mass ratio, 1.6g). Add Span40 and preheat in a 60℃ water bath for 15min. Add Tween40 and stir at 1500r / min for 20min. Then add 60g of white oil and continue stirring for 20min to form the oil phase.

[0052] The aqueous phase was slowly added dropwise to the oil phase, and the mixture was stirred for 10 minutes using a high-speed mixer to obtain an oil-water emulsion. The mixture was then stirred magnetically at 1000 rpm and reacted at a constant temperature of 70°C for 6 hours. After the reaction was complete, the mixture was allowed to stand for 10 minutes, after which clear stratification occurred. The oil phase was then poured off, and the mixture was centrifuged at 9000 rpm for 5 minutes. The product was first neutralized to neutral with 0.5M dilute hydrochloric acid, then washed sequentially with acetone, anhydrous ethanol, and deionized water, and finally air-dried at room temperature to obtain γ-cyclodextrin microspheres formed by reverse emulsion polymerization.

[0053] First, 200g of Artemisia argyi stems and leaves were steam-distilled with excess water for 3 hours, followed by static separation for 2 hours to obtain an oily distillate. Then, the distilled Artemisia argyi stem and leaf residue was placed in 600mL of 60% methanol aqueous solution and extracted at room temperature and pressure for 30 minutes under a hypergravity environment with a hypergravity factor of 1000. The filtrate was collected and concentrated to a paste. The concentrated paste and the distillate are the plant's active ingredients.

[0054] 1g of polyvinyl alcohol, 0.5g of starch, and 2g of glycerol were added to 30mL of deionized water and heated at 96℃ for 2 hours with stirring to prepare a membrane solution. γ-cyclodextrin microspheres (20% by weight of the membrane solution) were uniformly dispersed in 30g of the membrane solution using ultrasound. The solution was then sprayed onto the membrane to form a film, which was then air-dried to obtain a polyvinyl alcohol microsphere membrane. Plant active ingredients were then sprayed onto the polyvinyl alcohol microsphere membrane to form a polyvinyl alcohol insect-repellent and pesticide-loaded microsphere membrane.

[0055] Figure 2 Optical microscope image (left) and SEM image (right) of the β-cyclodextrin microspheres prepared in Example 3 are shown. Figure 3 Optical microscope (left) and SEM (right) images of the drug-loaded β-cyclodextrin microspheres / polyvinyl alcohol membrane prepared in Example 2 are shown. The images show that the prepared β-cyclodextrin microspheres exhibit good sphericity. Similarly, the cyclodextrin microspheres loaded onto the polyvinyl alcohol composite membrane maintain a good spherical shape. However, the product after natural air drying shows adhesion between the microspheres due to moisture loss, resulting in irregular protrusions on the surface of the microspheres.

[0056] Insect repellency test

[0057] Using 500g of camphor tree leaves as raw material, steam distillation was first performed for 6 hours with excess water, followed by static separation for 2 hours to obtain an oily distillate. The residue from the distillation was then placed in 1500mL of 20% ethanol and extracted for 40 minutes under a gravitational environment of 1000. The filtrate was collected and concentrated to a paste. The concentrated paste was combined with the distillate to obtain the plant's active ingredients. 100μL of the extract was placed in a glass petri dish, and 10 adult red flour beetles were introduced. All beetles died after 30 minutes.

[0058] 0.5g of the plant active ingredient was dissolved in 50mL of 20% methanol solution for dilution. 2mL of the diluted plant active ingredient was sprayed onto 30g of polyvinyl alcohol microspheres prepared in Example 3 to form a polyvinyl alcohol insect-repellent drug-loaded microsphere membrane. The polyvinyl alcohol insect-repellent drug-loaded microsphere membrane was placed in a glass petri dish as the sole food source, and 10 adult red flour beetles were introduced. The number of dead insects was checked after 24h, 48h, and 72h, and the mortality rate was calculated. The results showed that all adult insects were dead by the time of the 24h check.

[0059] The embodiments described above are merely preferred embodiments of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for extracting effective components from plants in a hypergravity field environment, characterized in that, Plants with insecticidal and insect-repellent properties were screened, and water was added for steam distillation to obtain a distillate. The plant residue was extracted with methanol or ethanol solution at room temperature and pressure under a hypergravity environment with a hypergravity factor of 2 to 2000. The filtrate was collected and concentrated to obtain a concentrated solution. The distilled extract and / or concentrate are the plant's active ingredients.

2. The method for extracting effective components from plants in a hypergravity field environment as described in claim 1, characterized in that, The plant is selected from one or more of the following: Artemisia argyi, camphor tree, mint, Sichuan pepper, Ailanthus altissima, oleander, and wolfsbane.

3. The plant active ingredients obtained by extracting using the method described in claim 1 or 2.

4. The use of the plant active ingredient as an insect repellent or in the preparation of insect-repellent microspheres according to claim 3.

5. An insect-repellent microsphere membrane, characterized in that, Using the plant active ingredient described in claim 3 as an insecticide, cyclodextrin microspheres as a drug-carrying and slow-release agent, polyvinyl alcohol as the main film-forming material, water as a solvent, and film-forming plasticizers and toughening agents added, after being dispersed evenly, the film is sprayed or coated and then air-dried to obtain the product. Alternatively, using the plant active ingredient as described in claim 3 as an insecticide and cyclodextrin microspheres as a drug-carrying and slow-release agent, the cyclodextrin microspheres are immersed in the plant active ingredient for impregnation and loading. Then, using polyvinyl alcohol as the main film-forming material and water as the solvent, film-forming plasticizers and toughening agents are added and dispersed evenly. The film is then sprayed or coated and air-dried to obtain the final product. Alternatively, cyclodextrin microspheres can be used as drug-carrying sustained-release agents, polyvinyl alcohol as the main film-forming material, water as the solvent, and film-forming plasticizers and toughening agents can be added. After being dispersed evenly, the film can be sprayed or coated, air-dried, and then the plant active ingredients described in claim 3 can be sprayed onto the film to obtain the final product.

6. An insect-repellent microsphere membrane, characterized in that, Using epichlorohydrin as a crosslinking agent, the plant active ingredients and cyclodextrin described in claim 3 are dissolved in an alkaline solution and crosslinked at room temperature to form an aqueous phase. The aqueous phase is then added dropwise to the oil phase, and the mixture is stirred to obtain an oil-water emulsion. The mixture is reacted at a constant temperature for a certain period of time, allowed to stand, the oil phase is poured off, centrifuged, washed, and dried to obtain drug-loaded microspheres. Then, using polyvinyl alcohol as the main film-forming material and water as the solvent, film-forming plasticizers and toughening agents are added and dispersed evenly. The mixture is then sprayed or coated to form a film, and air-dried to obtain the final product.

7. The insect-repellent microsphere membrane as described in claim 5 or 6, characterized in that, The film-forming plasticizer is a bio-polysaccharide, the toughening agent is glycerol, and the bio-polysaccharide is one or more of sodium alginate, chitosan, starch, and cellulose.

8. The insect-repellent microsphere membrane as described in claim 5, characterized in that, The cyclodextrin microspheres were prepared by the following method: using epichlorohydrin as a crosslinking agent, cyclodextrin was dissolved in alkaline solution and crosslinked at room temperature to form an aqueous phase. The aqueous phase was added dropwise to the oil phase and stirred to obtain an oil-water emulsion. The mixture was reacted at a constant temperature for a certain time, allowed to stand, the oil phase was poured off, centrifuged, washed, and dried to obtain the product. The oil phase is an oil solution containing surfactants Tween and Span, and the oil solution is one of white oil, silicone oil, and kerosene.

9. The insect-repellent microsphere membrane as described in claim 6, characterized in that, The cyclodextrin is one of α, β, or γ-cyclodextrin.

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