Use of amomum villosum oil for the preparation of mosquito repellents

Abstract

The application discloses application of Amomum tsao-ko oil in preparation of mosquito repellents. It is found that Amomum tsao-ko oil and eucalyptus oil have repellent activity on mosquitoes, and in order to further improve the mosquito repellent activity and solve the defect that plant essential oils are easy to volatilize, the Amomum tsao-ko oil and eucalyptus oil are compounded in a certain proportion to achieve a synergistic effect, and the mosquito repellent activity is high.

Description

Technical Field

[0001] The invention belongs to the field of sanitary pest control, and particularly relates to the application of tsaoko oil and eucalyptus oil in combination for preparing mosquito repellent. Background Art

[0002] Tsaoko oil is extracted from the fruit of the tsaoko plant (Amomum tsaoko Crevost et Lemarie), a perennial herb in the ginger family. The whole plant is used to extract aromatic oil. Tsaoko is a major edible and medicinal herb in traditional Chinese medicine. Its fruit has medicinal properties, such as dehumidifying, strengthening the spleen, and removing phlegm and preventing malaria (Chinese Pharmacopoeia 2020. Part 1. 2020: 249-250).

[0003] Eucalyptus oil is extracted from the eucalyptus plant. Eucalyptus (Eucalyptus globules Labill), also known as eucalyptus, is a plant of the genus Eucalyptus in the Myrtaceae family. Its essential oil has antibacterial and analgesic properties and is often widely used as the main raw material for mosquito repellents.

[0004] Current research on the use of plant essential oils for mosquito repellents indicates that most plant essential oils have some repellent effect against mosquitoes, though this effectiveness varies considerably. Due to their high volatility and short-lasting effects, plant essential oils have been formulated into mosquito repellent formulations using nano-sustainable-release materials, thereby extending the long-lasting effects of these oils. While relatively few studies have examined the use of plant essential oils in mosquito repellent formulations, as plant-derived substances, their potential for development in mosquito repellent formulations is promising due to their low environmental impact, resistance to drug resistance, and safety for human health. Summary of the Invention

[0005] The present invention has discovered that tsaoko oil and its combination with eucalyptus oil have mosquito repellent activity. Based on this, the present invention first provides the use of tsaoko oil in preparing a mosquito repellent. It also provides the use of tsaoko oil and eucalyptus oil in combination in preparing a mosquito repellent. Optionally, the mosquito repellent is a mosquito repellent essential oil, mosquito repellent lotion, mosquito repellent coil, mosquito repellent patch, mosquito repellent ointment, or other mosquito repellent product.

[0006] The present invention also provides a corresponding mosquito repellent. The mosquito repellent is a mosquito repellent nanoemulsion, the active ingredients of which are tsaoko oil and eucalyptus oil, with the volume ratio of tsaoko oil to eucalyptus oil being 1-9:9-1. Alternatively, the volume ratio of tsaoko oil to eucalyptus oil is 3-7:7-3. Furthermore, optionally, the volume ratio of tsaoko oil to eucalyptus oil is 5:5.

[0007] In a specific embodiment, the mosquito repellent is made from the following raw materials in percentage by volume: 5% to 10% of a blend of tsaoko and eucalyptus oils, 2% to 5% of a synergist, 5% to 10% of a surfactant, 0% to 5% of a co-surfactant, and the balance being deionized water, with the total volume percentages of the raw materials totaling 100%. Optionally, the synergist is one or a mixture of two or more of vanillin, citral, cuminaldehyde, cinnamaldehyde, or citronellal; the surfactant is one or a mixture of two or more of Tween 20, Tween 80, Span 20, and Span 80; and the co-surfactant is one or a mixture of two or more of anhydrous ethanol, n-propanol, n-butanol, and isobutanol.

[0008] The present invention also provides a method for preparing the mosquito repellent, which comprises the following steps:

[0009] S1, mixing the compound essential oil of tsaoko oil and eucalyptus oil with a synergist to obtain oil phase A;

[0010] S2, deionized water, surfactant and co-surfactant are mixed to obtain aqueous phase B;

[0011] S3, adding oil phase A while stirring aqueous phase B, and mixing to form a crude emulsion;

[0012] S4, the crude emulsion is treated with ultrasound to obtain mosquito repellent nanoemulsion.

[0013] Tsaoko oil and eucalyptus oil are natural plant-derived active substances. The present invention compounds tsaoko oil and eucalyptus oil in a certain proportion to achieve a synergistic effect, and has high mosquito repellent activity. DETAILED DESCRIPTION

[0014] Unless otherwise specified, the scientific and technical terms used herein are understood according to the knowledge of ordinary technicians in the relevant fields.

[0015] The applicant's research found that tsaoko oil showed high mosquito repellent activity against Aedes albopictus at different concentrations, and it can be compounded with eucalyptus oil, which has been proven to have good mosquito repellent activity, to prepare a mosquito repellent nanoemulsion with better mosquito repellent effect.

[0016] In order to more clearly understand the present invention and the efficacy of the medicament of the present invention, the present invention is further described in detail below through specific examples completed according to the technical solutions of the present invention provided by the inventors. These are merely preferred embodiments of the present invention, but are not limited to these embodiments. The essential oils, reagents, etc. used in the following examples are all commercially available products.

[0017] Example 1: Comparison of mosquito repellent activity of various plant essential oils

[0018] A Y-shaped olfactometer was used to determine the repellent activity of plant essential oils against adult female Aedes albopictus mosquitoes. The system consisted of a Y-shaped tube, a drying tower, a vacuum pump, a water tower, a sample chamber, and odorless silicone tubing. Under conditions of room temperature (26±1°C), relative humidity (RH) (65±10%), and light intensity (140 Lux), ambient air was purified by activated carbon adsorption in the drying tower before entering the water tower for humidification. The air then entered the sample chamber, passed through the arms of the Y-shaped tube, and entered the main tube at a flow rate of 160 mL / min. Finally, the air was discharged through the silicone tubing. After the Y-shaped olfactometer was installed, a microinjector was used to dispense a predetermined amount of essential oil onto a filter paper strip. This was then placed in one sample chamber. A filter paper strip of the same size, without essential oil, was placed in the other chamber as a control. After 20 seconds, 20 female mosquitoes were released from the insect introduction port. The number of mosquitoes in each arm was recorded at 5, 10, 15, and 20 minutes. Each experiment was repeated three times. The formula for calculating the repellency (PR) is as follows:

[0019] PR(%)=(Nc-Nt) / (Nc+Nt)×100

[0020] Nc: number of mosquitoes in the control arm;

[0021] Nt: number of mosquitoes in the treatment group.

[0022] Table 1 Preliminary screening of mosquito repellent activity of 10 plant essential oils (5.0 μL)

[0023]

[0024] Note: The above data are the results of three parallel determinations (mean ± error); 20 female mosquitoes in each group.

[0025] Table 1 Preliminary screening of mosquito repellent activity of 10 plant essential oils (5.0 μL)

[0026]

[0027]

[0028] Note: The above data are the results of three parallel determinations (mean ± error); 20 female mosquitoes in each group.

[0029] Table 1 shows the preliminary results of the mosquito repellent activity of 10 plant essential oils. As can be seen from Table 1, most plant essential oils exhibited good repellent activity at a dose of 5.0 μL. Eucalyptus oil and Amomum villosum oil showed particularly strong repellent activity, with repellency rates exceeding 90% after five minutes. Clove and basil also exhibited strong repellent activity, reaching over 80% at the fifth minute, but repellency rates decreased slightly at other times.

[0030] Example 2: Screening of compounding ratios of tsaoko oil and eucalyptus oil

[0031] Based on the preliminary screening results for the repellent activity of plant essential oils, the two plant essential oils with relatively good repellent effects were tsaoko oil and eucalyptus oil. Therefore, these two essential oils were selected for compounding [V(tsaoko oil):V(eucalyptus oil)] in ratios of 1:9, 3:7, 5:5, 7:3, and 9:1. The repellent activity of the plant essential oils in different ratios was determined using a human skin protection test (conducted in mosquito cages according to the test method of GB / T 13917.9-2009).

[0032] Table 2 shows the mosquito repellent activity of different ratios of tsaoko oil and eucalyptus oil. As can be seen from Table 2, at a dose of 24.0 μL, the effective protection duration of a 5:5 tsaoko oil:eucalyptus oil combination significantly outperformed the protection duration of either oil alone, reaching 82.5 minutes. Therefore, a 5:5 ratio is the preferred choice for this essential oil combination.

[0033] Table 2 Mosquito repellent activity of different ratios of tsaoko oil and eucalyptus oil (test method according to GB / T 13917.9-2009 was carried out in a mosquito cage, 24.0 μL)

[0034]

[0035]

[0036] Note: A represents V (tsaoko oil): V (eucalyptus oil); the sample size is 2 males and 2 females; the effective protection time is the average of four repetitions.

[0037] Example 3: Preparation of mosquito repellent nanoemulsion containing compound plant essential oil

[0038] The mosquito repellent nanoemulsion of this embodiment is formulated as follows: 9.6% tsaoko oil + 9.6% eucalyptus oil + 0.8% vanillin (synergist) + 5% Span 80 + 2.5% n-propanol + 72.5% distilled water. The preparation method is as follows:

[0039] S1, the essential oils of tsaoko oil and eucalyptus oil are mixed with vanillic aldehyde and thoroughly stirred. This system is used as oil phase A.

[0040] S2, deionized water, surfactant, and co-surfactant were measured and placed in a conical flask. The mixture was magnetically stirred at 600 rpm at room temperature for 15 min. This system was aqueous phase B.

[0041] S3, slowly adding the oil phase A while stirring the aqueous phase B, and homogenizing using a high-speed shearing machine at 10,000 rpm for a certain period of time to form a coarse emulsion;

[0042] S4. The crude emulsion is placed in a centrifuge tube and disrupted using an ultrasonic cell disruptor to obtain a milky white mosquito repellent nanoemulsion. The entire process is performed in an ice bath. The operating parameters of the ultrasonic cell disruptor are as follows: operating time: 4 seconds, rest time: 2 seconds.

[0043] Example 4: Determination of the repellent effect of plant essential oil mosquito repellent nanoemulsion on Aedes albopictus

[0044] 1. Materials and Methods

[0045] 1.1 Test materials

[0046] 1.1.1 Test insects

[0047] Aedes albopictus, cultured in the sanitary pest breeding room of the Pollution-Free Pesticide Research and Service Center of Northwest Agriculture and Forestry University.

[0048] 1.1.2 Test agents

[0049] 20% tsaoko oil and eucalyptus oil mosquito repellent nanoemulsion prepared in Example 3; 20% tsaoko oil and eucalyptus oil alcohol solution [V (tsaoko oil): V (eucalyptus oil) = 5:5]; Longliqi mosquito repellent; Frog Prince mosquito repellent.

[0050] The substance and formula of the 20% amomum villosum oil and eucalyptus oil alcohol solution are specifically: 10% amomum villosum oil + 10% eucalyptus oil + 80% ethanol.

[0051] 1.2 Bioassay Method (Human Skin Protection Test)

[0052] The test is carried out in accordance with the test method specified in GB / T 13917.9-2009, the national standard of the People's Republic of China.

[0053] 1.2.1 Attack power test

[0054] 300 test insects were placed in a mosquito cage. The tester exposed a 40mm x 40mm skin area on the back of their hand, with the rest of their body tightly covered. The tester placed their arm in the mosquito cage for 2 minutes. Observe for any mosquitoes that landed. Shake their arm to dislodge them before their mouthparts penetrated their skin. This was counted as one landing insect. If more than 30 test insects landed on the tester and the test insects, their aggression was considered acceptable, and this person and the mosquito cage were eligible for repellency testing.

[0055] 1.2.2 Repellency test

[0056] Select four or more testers with acceptable aggression resistance (half male and half female, and refraining from alcohol, tea, or coffee, or using products containing fragrances, before and during the test). Mark a 50 mm x 50 mm skin area on the back of each hand. Apply the repellent to be tested evenly to one hand at a dose of 1.5 μL / cm², exposing an area of ​​40 mm x 40 mm, while keeping the remainder tightly covered. The other hand serves as a blank control. Two hours after applying the repellent, place the hand in a mosquito cage with acceptable aggression resistance for two minutes and observe for mosquitoes landing and feeding. Tests are then repeated every hour. If even one mosquito feeds, the repellent is deemed ineffective. The effective protection duration (hours) of the repellent is recorded. Each time, a control test is performed on the control hand. Test insects with acceptable aggression resistance may continue the test; test insects with unacceptable aggression resistance must be replaced with qualified test insects.

[0057] 1.2.3 Calculation

[0058] The effective protection time of the drug for 4 or more subjects was added up, and the average (retaining one decimal place) was taken as the effective protection time (h) of the drug.

[0059] 1.2.4 Evaluation

[0060] The efficacy of the repellent was evaluated based on the effective protection time (h) of the test personnel.

[0061] The efficacy results are divided into two levels, A and B. Products that do not meet the B level standard are considered unqualified products.

[0062] Class A: effective protection time ≥ 6h; Class B: effective protection time ≥ 4h

[0063] 2 Results and Analysis

[0064] The human protection test method was used to systematically determine the effective protection time of the compound essential oil nanoemulsion on the human body. The results are shown in Table 3.

[0065] Table 3 Effective protection time of plant essential oil nano mosquito repellent ointment

[0066]

[0067]

[0068] As shown in Table 3, the 20% compound essential oil nanoemulsion has a good mosquito repellent effect, with an effective protection time of 240 minutes, which meets the national Class B standard for repellents. Compared with commercially available mosquito repellents, its effective protection time is longer.

[0069] In human skin protection tests, the compounded essential oil nanoemulsion not only demonstrated rapid effectiveness but also a longer-lasting effect than alcohol solutions of compounded essential oils. Furthermore, it is environmentally friendly and safe for human health, providing a sustained-release effect and extending the duration of mosquito repellency. Therefore, it is highly suitable for household pest and mosquito control and holds great potential for widespread application and promotion.

[0070] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to fall within the scope of protection claimed herein.

Claims

1. Application of tsaoko oil and eucalyptus oil in combination for preparing mosquito repellent, wherein the volume ratio of the tsaoko oil to the eucalyptus oil is 5:

5.

2. The use according to claim 1, characterized in that The mosquito repellent is mosquito repellent essential oil, mosquito repellent lotion, mosquito repellent coil, mosquito repellent patch or mosquito repellent ointment.

3. A mosquito repellent, characterized in that: The mosquito repellent is a mosquito repellent nanoemulsion, the active ingredients of the mosquito repellent nanoemulsion are tsaoko oil and eucalyptus oil, and the volume ratio of the tsaoko oil to the eucalyptus oil is 5:

5.

4. The mosquito repellent according to claim 3, characterized in that The mosquito repellent is prepared from the following raw materials in the following volume percentages: 5% to 10% of compound essential oil of tsaoko oil and eucalyptus oil, 2% to 5% of synergist, 5% to 10% of surfactant, 0% to 5% of co-surfactant, and the balance being deionized water, and the sum of the volume percentages of the raw materials is 100%.

5. The mosquito repellent according to claim 4, characterized in that The synergist is one or a mixture of two or more of vanillin, citral, cuminaldehyde, cinnamaldehyde or citronellal; the surfactant is one or a mixture of two or more of Tween20, Tween80, Span20 and Span80; and the cosurfactant is one or a mixture of two or more of anhydrous ethanol, n-propanol, n-butanol and isobutanol.

6. The method for preparing the mosquito repellent according to claim 4, characterized in that: The preparation method comprises the following steps: S1, mixing the compound essential oil of tsaoko oil and eucalyptus oil with a synergist to obtain oil phase A; S2, deionized water, surfactant and co-surfactant are mixed to obtain aqueous phase B; S3, adding oil phase A while stirring aqueous phase B, and mixing to form a crude emulsion; S4, the crude emulsion is treated with ultrasound to obtain mosquito repellent nanoemulsion.

Images