A natural mosquito repellent essential oil

Abstract

The application integrates representative citral, menthol, linalool, eucalyptol and camphor active substances in citronella oil, peppermint oil, chamomile oil, lavender oil and camphor oil to construct a multi-component and multi-pathway synergistic mosquito repellent system. The compound essential oil has broad-spectrum volatile components, good fragrance levels and stable and significant mosquito repellent effect.

Description

Technical Field

[0001] This application relates to the field of traditional Chinese medicine, and in particular to mosquito repellent essential oils. Background Technology

[0002] Mosquitoes are widely distributed in the natural environment and are important vectors for many infectious diseases such as dengue fever, malaria, and chikungunya. With climate change and accelerated urbanization, mosquito breeding grounds are expanding, and the risk of mosquito-borne diseases is on the rise. Therefore, developing safe and effective mosquito repellent products has significant public health implications and practical value.

[0003] Currently, mosquito repellent products mainly fall into two categories: chemically synthesized mosquito repellents and plant-based mosquito repellents. While chemically synthesized mosquito repellents are more effective, their main components are mostly artificially synthesized chemicals. Long-term or frequent use may irritate human skin and respiratory systems, and some components are difficult to degrade in the environment, posing certain safety and ecological risks. Therefore, natural, safe, and environmentally friendly mosquito repellent products are gradually becoming a research and application hotspot.

[0004] Natural plant essential oils are volatile substances obtained from aromatic plants through distillation, pressing, and other methods. They are rich in natural active ingredients such as terpenes, alcohols, aldehydes, and esters. Studies have shown that many plant essential oils have a certain repellent effect on mosquitoes, and their mechanism of action is mainly related to interfering with the mosquito's olfactory recognition system. Compared with chemically synthesized mosquito repellents, natural plant essential oils have advantages such as wide availability, relatively pleasant aroma, and good biodegradability, aligning with the trend of green and safe development.

[0005] However, existing essential oil mosquito repellent products still have certain shortcomings, such as a lack of scientific basis for compounding ratios and poor product stability and consistency, which restrict their practical application effectiveness. Therefore, it is necessary to develop a natural essential oil mosquito repellent product with natural plant essential oils as the main active ingredient, scientific compatibility, stable mosquito repellent effect, and high safety to overcome the shortcomings of existing technologies and meet the needs of the market and practical applications. Summary of the Invention

[0006] The purpose of this invention is to provide a safe and effective natural mosquito repellent essential oil.

[0007] The ingredients of this natural mosquito repellent essential oil are: lemongrass, peppermint, lavender, camphor oil, and chamomile.

[0008] The natural mosquito repellent essential oil is composed of the following herbal extracts: lemongrass essential oil, peppermint oil, lavender oil, camphor oil, and chamomile oil.

[0009] Composition and dosage of herbal extracts in natural mosquito repellent essential oil: lemongrass essential oil 0.5-5, peppermint essential oil 0.1-2, lavender oil 0.1-2, camphor oil 0.5-3, chamomile oil 0.5-5, in parts by weight.

[0010] Composition and dosage of herbal extracts in natural mosquito repellent essential oil: lemongrass essential oil 1.5, peppermint essential oil 0.5, lavender oil 1, camphor oil 1.5, chamomile oil 0.5, all in parts by weight.

[0011] Composition and dosage of herbal extracts in natural mosquito repellent essential oil: lemongrass essential oil 5, peppermint essential oil 2, lavender oil 2, camphor oil 3, chamomile oil 5, in parts by weight.

[0012] The GC-MS component analysis method of this invention: by comparing single essential oils and mosquito-repellent essential oils, the source and structural characteristics of mosquito-repellent active ingredients in compound essential oils are determined, providing a clear material basis for the mosquito-repellent formula of this invention.

[0013] This invention identifies the components of lemongrass oil, peppermint oil, chamomile oil, lavender oil, and camphor oil used in natural mosquito repellent essential oils using GC-MS.

[0014] 1. Test method: An Agilent 7890B-7000D gas chromatograph-triple quadrupole mass spectrometer was used.

[0015] GC conditions: Agilent HP-5MS UI column; temperature program: 50℃ for 3 min, increase to 70℃ at 10℃ / min, hold for 1 min, increase to 200℃ at 3℃ / min, hold for 5 min; carrier gas: helium; injector heater: 260℃; injection volume: 4 μL; splitless.

[0016] MS conditions: EI source; bombardment voltage 70 eV, ion source temperature 230℃, quadrupole temperature 150℃, scan quality range 50.00-500.00 amu, solvent delay 7.00 min.

[0017] One of the thin-layer detection methods of the present invention: 1. Preparation of reference solution: Take citral reference standard and add methanol to prepare a solution containing 2 mg of citral per 1 mL, which is used as the reference solution.

[0018] 2. Preparation of test solution: Dissolve 10 μL of natural mosquito repellent essential oil in 1 mL of methanol to prepare the test solution.

[0019] 3. Take appropriate amounts of the above test solution and reference solution, and spot them separately on silica gel GF. 250On the thin-layer plate, toluene-ethyl acetate (19:1) was used as the developing solvent. After development and drying, the plates were examined under ultraviolet light (254nm).

[0020] The results showed that the test sample and the reference sample of mosquito repellent essential oil showed the same spots at the corresponding spot positions on the chromatogram.

[0021] The second thin-layer detection method of the present invention: 1. Preparation of reference solution: Take linalool and linalool acetate reference standards, add methanol to prepare a solution containing 2 mg of each per 1 mL, as the reference solution.

[0022] 2. Preparation of test solution: Dissolve 10 μL of natural mosquito repellent essential oil in 1 mL of methanol to prepare the test solution.

[0023] 3. Take appropriate amounts of the above test solution and reference solution, and spot them separately on silica gel GF. 250 On the thin-layer plate, toluene-ethyl acetate (19:1) was used as the developing solvent. After development and drying, the plate was examined under a UV lamp (254nm). Then, it was sprayed with 5% vanillin-sulfuric acid solution and placed on a thin-layer heating plate at 105℃ until the spots were clearly visible.

[0024] The results showed that the mosquito repellent essential oil test sample and the linalool reference standard showed the same blue spots at the corresponding spot positions in the chromatogram; the mosquito repellent essential oil test sample and the linalyl acetate reference standard showed the same spots at the corresponding spot positions in the chromatogram.

[0025] Effects of the invention: The invention has the effects of strong repellency and wide range, long-lasting blocking and larval inhibition, low irritation and harmonious synergistic effect. Odor characteristics: The overall odor is rich in layers, mainly spicy and cool, with the heavyness of wood and the softness of flowers.

[0026] Synergistic effects of the present invention: The compound essential oil of the present invention, through optimization, achieves complementary and synergistic effects of active substances on the basis of the effects of single components, producing unexpected synergistic effects and endowing the compound essential oil with comprehensive advantages such as rapid volatilization, strong repellency, and long-lasting fragrance. The effective protection time of the present invention is 3.3 hours, and the repellency rate is 62.5% after 5 hours of application.

[0027] This invention integrates representative active substances such as citral, menthol, linalool, eucalyptol, and camphor from lemongrass oil, peppermint oil, chamomile oil, lavender oil, and camphor oil to construct a multi-component, multi-pathway synergistic mosquito repellent system. This compound essential oil possesses broad-spectrum volatile components, a pleasant aroma profile, and a stable and significant mosquito-repellent effect.

[0028] This invention identified the components of lemongrass essential oil, peppermint oil, chamomile oil, lavender oil, and camphor oil used in the formula using GC-MS. By comparing the compositional consistency between the single essential oil and the compound essential oil, the source and structural characteristics of the mosquito-repellent active ingredients in the compound essential oil can be determined, providing a clear material basis for the mosquito-repellent formula of this invention.

[0029] Comparison of the components of five single essential oils (lemongrass oil, peppermint oil, chamomile oil, lavender oil, and camphor oil) with the GC-MS spectra of compound essential oils revealed that the main components in the compound, including 1,8-cineole, linalool, menthol, menthone, terpineol, linalyl acetate, α-pinene, β-pinene, sapinene, limonene, β-citral, and trans-citral, can all be traced back to the five single essential oils.

[0030] Among them: lemongrass oil: provides β-citral and trans-citral, which are the main sources of citral components in the compound; peppermint oil: provides typical peppermint compounds such as menthol, menthone, and limonene; chamomile oil: provides linalool, some citral compounds, and angelic acid esters, which enhance the softness and complexity of the aroma; lavender oil: provides linalool, linalyl acetate, borneol, and some 1,8-cineole, contributing a stable floral base; camphor oil: provides highly volatile monoterpenes and oxygenated monoterpenes such as 1,8-cineole, camphor, 4-terpene alcohol, terpineol, α / β-pinene, and sapindus, which are important sources of eucalyptol, pinene, and terpineol components in the compound.

[0031] The above comparison shows that each major peak in the compound essential oil of the present invention can be traced back to the corresponding single essential oil, indicating that the composition of the mosquito repellent essential oil of the present invention has a clear material basis and is reproducible.

[0032] This invention simulates the interaction between seven main components of mosquito repellent essential oil (citral, menthol, 1,8-cineole, linalool, linalyl acetate, camphor, and α-bisabolol) and the insect olfactory co-receptor Orco using molecular docking technology. The docking results show that all seven compounds can bind to the Orco protein with high affinity.

[0033] Experimental examples of the present invention: Test method: Test subjects: The tested insect was the Aedes albopictus mosquito, female adults who had not yet fed on blood 4–7 days after emergence. Test conditions: Temperature 26.1℃, relative humidity 68%.

[0034] 1. Mosquito repellency duration test: Refer to GB / T13917.9-2024 Repellent Evaluation Standard 1.1 Attack Power Test: 300 test insects were placed in a mosquito cage. The tester's hand had a 40mm x 40mm exposed skin area on the back of their hand, with the rest completely covered. The tester then placed their hand inside the cage to observe the insects' landing. When an insect landed on the exposed surface and made a biting motion, the tester immediately shook their arm to scare it away, recording this as one instance of an insect landing. Testers and insects with more than 30 instances of insect landing within 2 minutes were considered to have passed the attack power test. Only testers and insects with passed the attack power test could proceed to the repellency test.

[0035] 1.2 Repellency Test: Select 4 or more test subjects with qualified aggression ability (half male and half female, and they should not drink alcohol, tea, or coffee before or during the test, nor use products containing fragrances). Mark a 50mm × 50mm area in the center of the skin on the back of each of their hands. Apply 1.5μL / cm to each hand. 2 The repellent was evenly applied to the marked area, exposing 40mm x 40mm of skin, while the rest was covered. The other hand served as a blank control. Two hours after application, the hand was placed inside a mosquito cage with acceptable attack power for 2 minutes to observe whether any mosquitoes came to land and feed. This was repeated every hour thereafter. If any mosquito came to feed within 2 minutes, the repellent was considered ineffective, and the protection time (in hours) was recorded. Each test began with an attack power test using the control hand. If the attack power was acceptable, the test continued; if the attack power was unacceptable, a suitable test insect was used, and the test was repeated.

[0036] 2.3 Calculation The effective protective times of the tested formulations in four or more subjects are summed, and the average (rounded to one decimal place) is taken as the protective time (H) of the formulation. The protective time H is calculated according to the following formula: H=(∑h_t) / N In the formula: H-Effective protection time: Ht - Individual effective protection time: N - Number of individuals in the experiment.

[0037] Avoidance rate test Based on the results of Experiment 1, 5 hours after applying mosquito repellent essential oil, the backs of the test subjects' hands were divided into a treatment group (applied mosquito repellent essential oil group) and a control group (untreated), and the number of mosquitoes landing in the two groups within 2 minutes was compared.

[0038] Calculation formula: Avoidance rate (%) = [(Number of exposures in the control group - Number of exposures in the treatment group) / Number of exposures in the control group] × 100.

[0039] Test results: The effective protection time of the present invention is 3.3 hours, and the repellency rate is 62.5% after 5 hours of application.

[0040] The tested formulations were: lemongrass essential oil 1.5, peppermint essential oil 0.5, lavender oil 1, camphor oil 1.5, and chamomile oil 0.5, in parts by weight.

[0041] 1. Results of mosquito repellent duration test Table 1 Results of mosquito repellency duration test

[0042] 2. Avoidance rate test results Table 2 Avoidance Rate Test Results

[0043] 1. Strong evasion and wide range: The citral in lemongrass (comprising 60%-80% of the essential oil's composition) binds tightly to mosquito pheromone receptors, blocking their recognition of lactic acid and ammonia in human sweat, thus preventing mosquitoes from finding their host. After volatilization, it forms a thin film on the skin, masking human odor and achieving an immediate repellency rate of 85%-90% against Aedes and Culex mosquitoes. It is particularly effective against Aedes aegypti, which transmits dengue fever and Zika virus; laboratory data show that a 2% concentration can reduce mosquito bites.

[0044] Menthol (comprising 50%-70% of the essential oil) and menthone in peppermint stimulate the chemoreceptors on mosquito antennae, inhibiting their ability to track carbon dioxide and body temperature. At high concentrations (≥3%), they can temporarily paralyze the mosquito's flight muscles. When blended with other essential oils, it can accelerate evaporation (by approximately 20%-30%) and expand the scent coverage, making it suitable for space diffusion.

[0045] 2. Long-lasting blocking and larval inhibition Linalool (comprising 30%-50% of the essential oil) in lavender can specifically block mosquitoes' memory association with their host's scent, especially effective against female mosquitoes during their egg-laying period (more active biters). Due to its moderate volatility, it can slow down the evaporation rate of other essential oils, extending the mosquito-repelling effect of blended products by 1-2 hours (e.g., when blended with lemongrass, the effect lasts from 4 hours to 5-6 hours). The linalyl acetate it contains can also alleviate histamine release after mosquito bites, reducing redness and itching, and improving the user experience.

[0046] Camphor (comprising 80%-90% of the essential oil's composition) and eucalyptol in camphor oil have strong odors that can directly irritate the respiratory system of mosquitoes, creating an "odor-free zone." This makes it particularly effective in enclosed spaces (such as wardrobes and cars), where a 2% concentration can achieve a mosquito avoidance rate of over 90%. Camphor evaporates very slowly (approximately 0.05 mg / h), leaving a lingering odor for 6-8 hours. Camphor oil also has contact-killing effects on mosquito eggs and larvae; laboratory data shows that a 3% camphor oil solution can inhibit 70% of mosquito egg hatching.

[0047] 3. Low irritation and synergistic effect Chamomile's gentle fruity and herbal scent can neutralize body odor and reduce the urge to bite insects, making it especially suitable for blending with strong-smelling essential oils such as lemongrass and camphor oil. Its anti-inflammatory components (alpha-bisabolol) can enhance tolerance to other essential oils and reduce irritation. When blended with lavender, it can indirectly prolong the oil's residence time by strengthening the skin barrier.

[0048] 4. Aroma characteristics: The overall aroma is rich and layered, mainly spicy and cool, with a combination of woody richness and floral softness. Top notes: The citrus scent of lemongrass intertwines with the soft floral notes of chamomile and lavender, resembling honey-soaked lemon; the impact of camphor and the coolness of mint are highly volatile, initially refreshing and invigorating.

[0049] Middle notes: A blend of herbal and woody notes including lavender, camphor oil, and lemongrass.

[0050] Base notes: Camphor oil's long-lasting resinous and earthy scent, similar to the richness of myrrh or frankincense; lavender's long-lasting woody musk base, similar to a blend of fir and amber, with a warm and lingering fragrance; chamomile's gentle beeswax and vanilla notes, blending together for a long finish. Attached Figure Description

[0051] Figure 1 Peppermint oil component; Figure 2 Lemongrass essential oil components; Figure 3 Lavender oil is a key ingredient. Figure 4 Chamomile oil is a key ingredient. Figure 5 Camphor oil component; Figure 6 Mosquito repellent essential oil ingredients; Figure 7 Chromatogram of citral thin-layer chromatography for identification; Figure 8 Chromatograms for the thin-layer identification of linalool and linalool acetate; Figure 9 Molecular docking of mosquito repellent essential oils; Detailed Implementation Example 1: Composition and dosage of herbal extracts in mosquito repellent essential oil: lemongrass essential oil 1.5, peppermint essential oil 0.5, lavender oil 1, camphor oil 1.5, chamomile oil 0.5, in grams.

[0052] Example 2: Composition and dosage of medicinal extracts in mosquito repellent essential oil: lemongrass essential oil 5g, peppermint essential oil 2g, lavender oil 2g, camphor oil 3g, chamomile oil 5g, in grams.

[0053] Example 3: One of the detection methods of the present invention This invention performed GC-MS component identification on lemongrass essential oil, peppermint oil, chamomile oil, lavender oil, and camphor oil used in the formulation of Example 1. By comparing the compositional consistency between the single essential oils and the compound essential oil of Example 1, the source and structural characteristics of the mosquito-repellent active ingredients in the compound essential oil were determined, providing a clear material basis for the mosquito-repellent formulation of this invention.

[0054] 1. Test method: An Agilent 7890B-7000D gas chromatograph-triple quadrupole mass spectrometer was used.

[0055] GC conditions: Agilent HP-5MS UI column; temperature program: 50℃ for 3 min, increase to 70℃ at 10℃ / min, hold for 1 min, increase to 200℃ at 3℃ / min, hold for 5 min; carrier gas: helium; injector heater: 260℃; injection volume: 4 μL; splitless.

[0056] MS conditions: EI source; bombardment voltage 70 eV, ion source temperature 230℃, quadrupole temperature 150℃, scan mass range 50.00-500.00 amu, solvent delay 7.00 min. Compound characterization was performed using the National Institute of Standards and Technology (NIST) standard spectral library.

[0057] Figure 1 Peppermint oil components Figure 2 Lemongrass essential oil components Figure 3 Lavender oil components, Figure 4 Chamomile oil components Figure 5 Camphor oil components Figure 6 It contains mosquito repellent essential oil ingredients.

[0058] Example 4: The second detection method of the present invention 1. Preparation of reference solution: Take citral reference standard and add methanol to prepare a solution containing 2 mg of citral per 1 mL, which is used as the reference solution.

[0059] 2. Preparation of test solution: Take 10 μL of the natural mosquito repellent essential oil from Example 1 and dissolve it in 1 mL of methanol to prepare the test solution.

[0060] 3. Take the above test solution and reference solution and spot them separately on silica gel GF. 250 On the thin-layer plate, toluene-ethyl acetate (19:1) was used as the developing solvent. After development and drying, the plates were examined under ultraviolet light (254nm).

[0061] Figure 7 This is a thin-layer chromatogram for the identification of citral. Figure 7 In the sample, 1. citral reference standard, 2. 5 μL of mosquito repellent essential oil test sample, 3. citral reference standard, and 4. 10 μL of mosquito repellent essential oil test sample.

[0062] The results showed that the test sample and the reference sample of mosquito repellent essential oil showed the same spots at the corresponding spot positions on the chromatogram.

[0063] Example 5: The third detection method of the present invention 1. Preparation of reference solution: Take linalool and linalool acetate reference standards, add methanol to prepare a solution containing 2 mg of each per 1 mL, as the reference solution.

[0064] 2. Preparation of test solution: Take 10 μL of the natural mosquito repellent essential oil from Example 1 and dissolve it in 1 mL of methanol to prepare the test solution.

[0065] 3. Take the above test solution and reference solution and spot them separately on silica gel GF. 250 On the thin-layer plate, toluene-ethyl acetate (19:1) was used as the developing solvent. After development and drying, the plate was examined under a UV lamp (254nm). Then, it was sprayed with 5% vanillin-sulfuric acid solution and placed on a thin-layer heating plate at 105℃ until the spots were clearly visible.

[0066] Figure 8 This is a thin-layer chromatogram for the identification of linalool and linalool acetate. Figure 8 In the test: 1. Citral reference standard, 2. Linalool reference standard, 3. 5 μL of mosquito repellent essential oil sample, 4. Linaloyl acetate reference standard, 5. 10 μL of mosquito repellent essential oil sample.

[0067] The results showed that the mosquito repellent essential oil test sample and the linalool reference standard showed the same blue spots at the corresponding spot positions in the chromatogram; the mosquito repellent essential oil test sample and the linalyl acetate reference standard showed the same spots at the corresponding spot positions in the chromatogram.

[0068] Example 6: The third detection method of the present invention Methods of molecular docking technology We obtained the crystal structure of the key target protein Orco from the PDB database and employed a systematic molecular docking strategy for structure optimization. Using the Sulflex-Dock-Define SFXC File module in Sybyl-X2.0 software, we preprocessed the protein structure, removing irrelevant ligands such as water of crystallization, adding polar hydrogen atoms, and assigning a Gasteiger-Marsili charge distribution. We then performed 1000 iterations of energy minimization optimization using a Tripos force field to achieve a stable conformation. The Surflex-Docking module was used for molecular docking, calculating the interaction between the ligand molecules and the protein. The optimized small molecules were then individually docked with the protein's active pocket. An empirical scoring function was used to evaluate the binding force between each ligand molecule and the target protein; a higher Total Score indicates a stronger binding between the protein and the small molecule.

[0069] 5. Analysis of docking results Using molecular docking technology, the interaction between seven main components of mosquito repellent essential oil (citral, menthol, 1,8-cineole, linalool, linalyl acetate, camphor, and α-bisabolol) and the insect olfactory co-receptor Orco was simulated. The docking results showed that all seven compounds bound to the Orco protein quite strongly.

[0070] Table 3 Molecular docking results

Claims

1. A mosquito repellent essential oil, characterized in that... It is composed of the following ingredients: lemongrass essential oil 0.5-5, peppermint essential oil 0.1-2, lavender oil 0.1-2, camphor oil 0.5-3, and chamomile oil 0.5-5, in parts by weight.

2. A mosquito repellent essential oil, characterized in that... It is composed of the following ingredients: lemongrass essential oil 1.5, peppermint essential oil 0.5, lavender oil 1, camphor oil 1.5, chamomile oil 0.5, in parts by weight.

3. A mosquito repellent essential oil according to claim 1 or 2, characterized in that: GC-MS analysis was performed on the natural mosquito repellent essential oil and the lemongrass essential oil, peppermint oil, chamomile oil, lavender oil and camphor oil used in it; An Agilent 7890B-7000D gas chromatograph-triple quadrupole mass spectrometer was used. GC conditions: Agilent HP-5MS UI column; temperature program: 50℃ for 3 min, ramp to 70℃ at 10℃ / min, hold for 1 min, ramp to 200℃ at 3℃ / min, hold for 5 min; helium as carrier gas; injector heater 260℃; injection volume 4 μL; splitless. MS conditions: EI source; bombardment voltage 70 eV, ion source temperature 230℃, quadrupole temperature 150℃, scan quality range 50.00-500.00 amu, solvent delay 7.00 min.

4. A mosquito repellent essential oil according to claim 1 or 2, characterized in that: Thin-layer liquid chromatography analysis of natural mosquito repellent essential oils: Preparation of reference solution: Take citral reference standard and add methanol to prepare a solution containing 2 mg per 1 mL, which is used as the reference solution; Preparation of test solution: Dissolve 10 μL of natural mosquito repellent essential oil in 1 mL of methanol to prepare the test solution; Take appropriate amounts of the above test solution and reference solution, and spot them separately on silica gel GF. 250 On the thin-layer plate, toluene-ethyl acetate 19:1 was used as the developing solvent. After development and drying, the plate was examined under a UV lamp at 254 nm. The test sample and the reference sample of mosquito repellent essential oil showed the same spots at the corresponding spot positions in the chromatogram.

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