Preparation method and application of plant-derived mosquito-preventing and insect-repelling hydrogel type solid mosquito repellent

Abstract

The invention belongs to the technical field of mosquito control, and particularly relates to a preparation method and application of a plant-derived mosquito-preventing and insect-repelling hydrogel type solid mosquito repellent. Nerolidol, limonene and vanillin are mixed according to the volume ratio of 5: 5: 2 to serve as effective components, the hydrogel type solid mosquito repellent is prepared, and the defect that essential oil is short in mosquito repellent action time is overcome. The effective mosquito repelling time is longer than 25 days. Meanwhile, the slow-release mosquito repellent can achieve the effects of environmental protection and efficient mosquito repelling while reducing the chemical pesticide resistance of deet.

Description

Technical Field

[0001] This invention relates to the field of mosquito control technology, and in particular to a method for preparing and applying a plant-derived hydrogel-type solid mosquito repellent. Background Technology

[0002] Mosquitoes are among the most widespread insects globally and are key vectors for many infectious diseases, such as dengue fever and chikungunya, making them a primary target for global public health control. Commonly used ingredients in commercial mosquito repellent formulations include DEET, N,N-diethylphenylacetamide (DEPA), dimethyl phthalate (DMP), N,N-diethylbenzamide (DEBA), and permethrin. These repellents are synthetic chemicals that are non-biodegradable, and long-term, large-scale use may impact the environment and ecosystems. In recent years, driven by environmental, safety, and health concerns, there has been increasing attention to the resistance, side effects, toxicity to non-target organisms, and ecological problems associated with synthetic repellents and insecticides. Therefore, natural, non-toxic mosquito repellent ingredients have become an important area of ​​research and development.

[0003] Plant essential oils contain a variety of chemical components. Some plant essential oils have been verified to have insecticidal and insect-repellent effects, and are widely studied due to their advantages such as low toxicity to humans and animals and no environmental pollution. For example, patent CN117530899A discloses that lavender extract, soybean extract, and lemon balm extract plant essential oils have natural mosquito-repellent effects. Patent CN111903678A discloses that geranium oil, citronella oil, and peppermint oil have a strong repellent effect on Aedes albopictus mosquitoes.

[0004] However, plant essential oils are less commonly used because they are volatile, have a short duration of effect, and are less effective than chemical mosquito repellents. Summary of the Invention

[0005] This invention aims to develop a plant-derived hydrogel-type solid mosquito repellent composition. By screening essential oil combinations with strong mosquito-repellent effects and optimizing the time-release process, a plant-derived hydrogel-type solid mosquito repellent composition is finally prepared to achieve an environmentally friendly, highly effective, and long-lasting mosquito-repellent effect.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a plant-derived hydrogel-type solid mosquito repellent, characterized in that it comprises nerolidol, limonene, and vanillin; wherein the volume ratio of nerolidol, limonene, and vanillin is 2~4:5~10~5~10.

[0008] Furthermore, the plant-derived mosquito repellent hydrogel solid mosquito repellent is characterized in that the volume ratio of nerolidol, limonene and vanillin is 2:5:5.

[0009] Furthermore, the plant-derived mosquito repellent hydrogel-type solid mosquito repellent is characterized by further comprising an emulsifier, tartrazine, and carrageenan.

[0010] Furthermore, the plant-derived hydrogel-type solid mosquito repellent is characterized by:

[0011] The total mass percentage of nerolidol, eugenol and vanillin is 5-10%, the mass percentage of emulsifier is 3-5%, the mass percentage of tartrazine is 0.2-1%, the mass percentage of carrageenan is 1-1.5%, and the balance is purified water.

[0012] Furthermore, the plant-derived hydrogel-type solid mosquito repellent is characterized in that: the mass percentage of the mixture of nerolidol, limonene and vanillin is 5%, the mass percentage of the emulsifier is 3%, the mass percentage of lemon yellow is 0.2%, and the remainder is purified water.

[0013] Furthermore, the plant-derived mosquito repellent hydrogel-type solid mosquito repellent is characterized in that the emulsifier is Tween 80.

[0014] Secondly, the present invention provides a method for preparing a plant-derived hydrogel-type solid mosquito repellent as described above, characterized by comprising the following steps:

[0015] S1: Prepare a formulation by mixing nerolidol, eugenol, vanillin, and emulsifier;

[0016] S2: Prepare carrageenan with pure water, heat the carrageenan aqueous solution, and stir until completely dissolved to obtain a carrageenan solution;

[0017] S3: When the carrageenan cools to 30~40℃, add the preparation from S1 and lemon yellow, stir, pour into a round mold, and cool to room temperature to obtain a plant-derived hydrogel-type solid mosquito repellent.

[0018] Thirdly, the present invention provides the application of the plant-derived mosquito repellent hydrogel-type solid mosquito repellent in the preparation of mosquito repellent products.

[0019] This invention, through screening the components of walnut leaf essential oil, discovered that the binary mixture of nerolidol and limonene has a synergistic mosquito-repellent effect, with an insect-repellent efficacy close to that of pyrethroids at the same content. Based on this, a hydrogel-type solid mosquito repellent was developed, using a mixture of nerolidol, limonene, and vanillin in a volume ratio of 5:5:2 as the active ingredient. This overcomes the short-lasting effect of essential oils, providing effective mosquito repellency for more than 25 days. Simultaneously, this slow-release mosquito repellent reduces the chemical pesticide resistance of DEET while achieving an environmentally friendly and highly effective mosquito-repellent effect. Attached Figure Description

[0020] Figure 1 The "Y"-shaped olfactory device is used for mosquito repellent experiments. 1 is the air inlet, 2 is the air outlet, 3 is the odorless silicone tube, 4 is the activated carbon device, and 5 is the water container.

[0021] Figure 2 This is a real photo of a hydrogel-type solid mosquito repellent.

[0022] Figure 3 This is a schematic diagram illustrating the effect of a hydrogel-type solid slow-release mosquito repellent. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Reagents not specifically described in detail herein are all conventional reagents and are commercially available; methods not specifically described in detail are all conventional experimental methods and can be learned from the prior art.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor do they substantially limit the technical features thereafter. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] To better understand the invention and not to limit its scope, all figures indicating amounts, percentages, and other numerical values ​​used in this application should, in all cases, be understood to be modified by the word "approximately." Therefore, unless specifically stated otherwise, the numerical parameters listed in the specification and appended claims are approximate values ​​and may vary depending on the desired properties being sought. Each numerical parameter should at least be considered as obtained based on reported significant figures and through conventional rounding methods.

[0026] This invention provides a plant-derived hydrogel-type solid mosquito repellent, the components of which include nerolidol, limonene and vanillin; the volume ratio of nerolidol, limonene and vanillin is 2~4:5~10~5~10.

[0027] In some embodiments, the volume ratio of nerolidol, limonene, and vanillin in the plant-derived mosquito repellent hydrogel solid mosquito repellent is 2:5:5.

[0028] In some embodiments, the ingredients of plant-derived hydrogel-type solid mosquito repellents in China also include emulsifiers, tartrazine, and carrageenan.

[0029] In some embodiments, the total mass percentage of nerolidol, eugenol and vanillin in the plant-derived mosquito repellent hydrogel solid mosquito repellent is 5-10%, the mass percentage of emulsifier is 3-5%, the mass percentage of tartrazine is 0.2-1%, the mass percentage of carrageenan is 1-1.5%, and the balance is purified water.

[0030] In some embodiments, the mass percentage of the mixture of nerolidol, limonene and vanillin in the plant-derived mosquito repellent hydrogel solid mosquito repellent is 5%, the mass percentage of the emulsifier is 3%, the mass percentage of tartrazine is 0.2%, and the balance is purified water.

[0031] In some embodiments, the emulsifier in the plant-derived mosquito repellent hydrogel type solid mosquito repellent is Tween 80.

[0032] Based on the same inventive concept, the present invention also provides a method for preparing a plant-derived hydrogel-type solid mosquito repellent, comprising the following steps:

[0033] S1: Prepare a formulation by mixing nerolidol, eugenol, vanillin, and emulsifier;

[0034] S2: Prepare carrageenan with pure water, heat the carrageenan aqueous solution, and stir until completely dissolved to obtain a carrageenan solution;

[0035] S3: When the carrageenan cools to 30~40℃, add the preparation from S1 and lemon yellow, stir, pour into a round mold, and cool to room temperature to obtain a plant-derived hydrogel-type solid mosquito repellent.

[0036] Based on the same inventive concept, the present invention also provides the application of a plant-derived hydrogel-type solid mosquito repellent in the preparation of mosquito repellent products.

[0037] Example 1: Repellent activity of volatile monomeric compounds from walnut leaves against Aedes albopictus mosquitoes.

[0038] Twenty-four monomeric compounds were tested for mosquito repellency, with insecticide polyester serving as a control. The mosquito repellency rate of each compound was tested at a reagent dosage of 0.2 wt% (wt: percentage of solute mass to total solution mass) for 5-20 minutes. The testing method employed a Y-shaped olfactory probe. Tests were conducted in an empty room with conditions identical to those for raising Aedes albopictus mosquitoes. An odorless silicone tube was used to connect the air outlet to an activated carbon air filter, water, and the Y-shaped tube in sequence (e.g.,...). Figure 1 (As shown). All instruments need to be cleaned and dried before assembly. Before the formal test, the instrument needs to be run for 5 minutes to check the connection and sealing of the device. After confirming there are no leaks, the test can begin. During the test, a certain number of female mosquitoes are sucked up using a mosquito aspirator and transferred into a "Y"-shaped tube. A certain amount of the test compound sample solution is drawn onto filter paper using a pipette and placed at the gas inlet on one side of the "Y"-shaped tube. Filter paper with the same amount of diluent is placed at the gas inlet on the other side as a control. The gas flow rate is set to 45 mL / min. Then the air inlet switch is opened to conduct the test. The number of mosquitoes in the two branches of the tube is recorded at different times according to the test requirements. Each group is repeated 4 times, with a repetition interval of half an hour, and the positions of the control group and the experimental group at both ends of the "Y"-shaped tube need to be swapped. The repellency rate is calculated according to the following formula.

[0039] Percentage repellency (PR%) = (CT) / (C + T) × 100%

[0040] If a test compound's mosquito-repellent rate falls below 50% within 5 minutes during the test, subsequent tests are discontinued. The results are shown in Table 1. Among the 24 volatile monomeric compounds from walnut leaves, most showed mosquito-repellent effects within 5 minutes. For example, (-)-pyrethroid D, caryophyllene, and eucalyptol exhibited repellency rates exceeding 85% within 5 minutes, but these rates gradually decreased over time. Limonene, (E)-β-farnesene, (+)-α-terpineol, and nerolidol showed the best repellent activity against Aedes albopictus, achieving a repellency rate exceeding 90% within 20 minutes at a 0.1 wt% reagent dosage. In contrast, pyrethroids, used as a positive control, achieved a 100% repellency rate within 20 minutes at the same dosage.

[0041] Table 1. Screening of repellent activity of volatile monomeric compounds from walnut leaves against Aedes albopictus.

[0042]

[0043] Note: Data represent mean ± standard error, 3 replicates, 25 female mosquitoes tested in each replicate. "―" indicates that the mosquito repellency rate of the compound is less than 50% within 5 minutes and the data was not tested.

[0044] Example 2: Synergistic effect of two volatile oil monomer compounds from walnut leaves as mosquito repellents

[0045] The mosquito repellent test results showed that limonene, (E)-β-farnesene, (+)-α-terpineol, and nerolidol were the most effective against Aedes albopictus. Nerolidol and limonene were chosen for testing due to their low price. Because nerolidol and limonene have significantly different functional groups and molecular structures, both were studied individually and in combination (volume ratio 1:1), and their mosquito repellency rates at different time points were measured. The reagent dosage was 0.1% by mass, with pyrethroid as a control. The results are shown in Table 2.

[0046] The results showed that the binary mixture of nerolidol and limonene had the best mosquito-repellent effect. At a concentration of 0.1% by mass, the repellency rate against Aedes albopictus was 66.69% within 30 minutes, significantly higher than that of nerolidol and limonene alone at the same concentration, but weaker than that of the control group pyrethroid (which had a repellency rate higher than 82.66% within 30 minutes), indicating a certain synergistic effect between nerolidol and eugenol.

[0047] Table 2 Synergistic effects of mosquito repellent monomeric compounds

[0048]

[0049] Note: Data represent mean ± standard error, with 3 replicates. Each replicate tested 25 female mosquitoes. Different letters after the data in the same column indicate significant differences (P<0.05).

[0050] Example 3: The delayed-effect synergistic effect of vanillin on mosquito-repellent monomeric compounds

[0051] This study used vanillin as a synergist and nerolidol and limonene as the active insect repellent components to investigate the mosquito-repellent effect of vanillin combined with the monomeric compounds nerolidol and limonene. Table 3 shows that vanillin itself has no repellent activity against Aedes albopictus. Within 20 minutes of application, vanillin did not significantly increase the mosquito-repellent activity of the compound. However, at 60 minutes, vanillin significantly increased the mosquito-repellent activity of the compound, and the mosquito-repellent rate at 60 minutes when used in combination with the synergist nerolidol and limonene was comparable to that of pyrethroids, indicating that vanillin can increase the mosquito repellency rate by extending the application time.

[0052] Table 3. Synergistic effect of vanillin on the mosquito-repellent effects of nerolidol and limonene

[0053]

[0054] Note: Data represent mean ± standard error, with 3 replicates. Each replicate tested 25 female mosquitoes. Different letters after the data in the same column indicate significant differences (P<0.05).

[0055] Example 4: Preparation and efficacy evaluation of hydrogel-type solid sustained-release mosquito repellent.

[0056] 4.1 Preparation of hydrogel-type solid slow-release mosquito repellent

[0057] Prepare carrageenan, tartrazine, purified water, a beaker, an emulsifier (Tween 80), and monomer compounds (nerolidol, limonene, and vanillin). First, prepare a 1.5% carrageenan solution with purified water, stirring thoroughly with a glass rod. Then, heat the carrageenan-containing aqueous solution in a microwave oven or on a metal stand, stirring constantly until the carrageenan is completely dissolved. In another beaker, prepare a formulation by mixing 0.1% of the monomer compounds and 3% of the emulsifier according to the specified mass ratio. Weigh out 0.2% of the tartrazine pigment according to the specified mass ratio. When the carrageenan temperature drops to 30-40 degrees Celsius, add the prepared formulation and pigment. Continue stirring with a glass rod for 2 minutes to evenly disperse the monomer compounds in the hydrogel. Immediately pour the mixture into a prepared circular mold and allow it to cool to room temperature. The process is complete when the temperature has cooled to room temperature.

[0058] Based on the experimental results of Example 3, the mosquito repellent combination of vanillin + nerolidol + limonene with the best mosquito repellent effect was selected to prepare mosquito repellent 1: vanillin and nerolidol were mixed at a volume ratio of 1:5, and the entire mixture accounted for 0.1% of the total mass; mosquito repellent 2: vanillin and limonene were mixed at a volume ratio of 1:5, and the entire mixture accounted for 0.1% of the total mass.

[0059] Mosquito Repellent 3: Vanillin, nerolidol, and limonene are mixed in a volume ratio of 2:5:5, with the entire mixture comprising 0.1% of the total mass. The finished product's effect is as follows... Figure 2 As shown.

[0060] 4.2 Evaluation of the efficacy of hydrogel-type solid sustained-release mosquito repellent

[0061] The mosquito repellents 1, 2, and 3 prepared in section 4.1 were left exposed for different periods (5 days, 15 days, 25 days, and 35 days). Three 5×5×5mm hydrogel blocks were then cut from different locations on each hydrogel repellent, ensuring that the cuts were made at the same location for each repellent. The testing method was the same as in Example 1, except that in this example, the hydrogel blocks were placed at the gas inlet on one side of the "Y"-shaped tube. The repellency rate was calculated using the following formula:

[0062] Percentage repellency (PR%) = (CT) / (C + T) × 100%

[0063] In the above formula, C represents the number of mosquitoes in the control branch and T represents the number of mosquitoes in the treatment branch.

[0064] The results showed that mosquito repellent 3 was the most effective, and the prepared hydrogel-type solid mosquito repellent was placed in an open container at room temperature.

[0065] The repellency rate against Aedes albopictus was greater than 98% after 5, 15, and 25 days, but the repellency activity was only 35.33% after 35 days (see results). Figure 3 After 35 days, the contents of the mosquito repellent sample gradually dried and shrank, and the characteristic odor of the essential oil faded.

[0066] Table 4 Evaluation of the mosquito-repellent effect of hydrogel-type solid slow-release mosquito repellents

[0067]

[0068] Note: The control group consisted of gel blocks without added compounds.

[0069] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A plant-derived hydrogel-type solid mosquito repellent, characterized in that: It includes nerolidol, limonene, and vanillin; the volume ratio of nerolidol, limonene, and vanillin is 2~4:5~10:5~10.

2. The plant-derived mosquito repellent hydrogel-type solid mosquito repellent according to claim 1, characterized in that: The volume ratio of nerolidol, limonene, and vanillin is 2:5:

5.

3. The plant-derived mosquito repellent hydrogel-type solid mosquito repellent according to claim 1, characterized in that: It also includes emulsifiers, tartrazine, and carrageenan.

4. The plant-derived mosquito repellent hydrogel-type solid mosquito repellent according to claim 3, characterized in that: The total mass percentage of nerolidol, eugenol and vanillin is 5-10%, the mass percentage of emulsifier is 3-5%, the mass percentage of tartrazine is 0.2-1%, the mass percentage of carrageenan is 1-1.5%, and the balance is purified water.

5. The plant-derived mosquito repellent hydrogel-type solid mosquito repellent according to claim 4, characterized in that: The mass percentage of the mixture of nerolidol, limonene and vanillin is 5%, the mass percentage of the emulsifier is 3%, the mass percentage of the pigment is 0.2%, and the remainder is purified water.

6. The plant-derived mosquito repellent hydrogel-type solid mosquito repellent according to claim 5, characterized in that, The emulsifier mentioned is Tween 80.

7. A method for preparing a plant-derived mosquito repellent hydrogel-type solid mosquito repellent as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Prepare a formulation by mixing nerolidol, eugenol, vanillin, and emulsifier; S2: Prepare carrageenan with pure water, heat the carrageenan aqueous solution, and stir until completely dissolved to obtain a carrageenan solution; S3: When the carrageenan cools to 30~40 ℃, add the preparation in S1 and lemon yellow, stir, pour into a round mold, and cool to room temperature to obtain a plant-derived mosquito repellent hydrogel solid mosquito repellent.

8. The use of the plant-derived mosquito repellent hydrogel solid mosquito repellent according to claim 1 in the preparation of mosquito repellent products.

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