Gelatinization method and application of plant essential oil

Abstract

According to the gel of the plant essential oil and the preparation method of the gel, the plant essential oil is used as a matrix and an active component, a small amount of sodium hydroxide is directly used as a gelator, and other gel materials do not need to be added, so that the plant essential oil forms a rapid and stable gel state. Different from common grease, most components in the essential oil cannot be subjected to saponification reaction, so that gelation of the plant essential oil is not based on saponification reaction. The preparation method of the plant essential oil gel is simple, convenient and efficient, and easy for expanded production; and the obtained essential oil is improved in gel stability and convenient to store, transport and apply.

Description

Technical Field

[0001] The invention relates to the technical field of medicines, and in particular to an essential oil gel and a preparation method thereof. Background Art

[0002] Essential oils, also known as volatile oils or aromatic oils, are volatile oily liquids found in leaves, roots, barks, flowers and fruits of plants. They can be extracted by steam distillation, pressing and other methods. They come from a wide range of sources, including Lamiaceae, Myrtaceae, Lauraceae and others. Most essential oils are transparent and colorless, but some are light yellow, light green, amber or dark brown.

[0003] Essential oils are lipophilic, water-resistant, highly permeable, and highly volatile. They have a special aroma and contain a variety of bioactive ingredients, including antibacterial, antioxidant, and antiviral properties. These properties make them widely used in many fields such as food industry, health care, and cosmetics. However, pure essential oils are easily oxidized under light or high temperature, have poor stability, and are highly irritating to the skin, which seriously hinders their clinical application. The existing technology enhances the stability of essential oils through cyclodextrin and its derivative inclusion, starch inclusion, solidification using adsorbents (such as calcium silicate and barium silicate of metal silicates), and nanoformulation technology. However, the inclusion or adsorption effect depends on the molecular size or physical and chemical properties of the essential oil. Among them, nanoformulation technology also has problems such as expensive carrier materials, low oil loading, and potential accumulation in the body. It is urgent to develop a simple and efficient essential oil solidification technology to facilitate its storage and use.

[0004] The main components of plant essential oils are alkenes, phenols and alcohols. For example, the main components of peppermint oil are limonene, menthone, isomenthone, caryophyllene, menthol, etc. In order to utilize essential oils in the prior art, essential oils can be prepared into essential oil soap products, which are obtained by subjecting a strong base such as potassium hydroxide to a saponification reaction with oils and fats to obtain a saponification product, and further adding plant essential oils to the saponification product to mix to obtain the product, wherein the plant essential oils are used as active ingredients therein and do not participate in the saponification and solidification of the product. In particular, unlike ordinary oils and fats, since most of the components in the essential oils cannot undergo a saponification reaction, the essential oils cannot be solidified by a saponification reaction. For example, potassium hydroxide is often used as a reagent to measure the acid value of plant essential oils, and the above experiment is obviously based on the fact that plant essential oils will not be solidified by potassium hydroxide.

[0005] Oleogel consists of an oil phase and an oleogelator, and gelation is achieved by binding liquid oil through a three-dimensional network structure constructed by the gelator. At present, commonly used gelators for preparing oleogels include monoglycerides, phytochemical components (such as sterols and oryzanol), fatty acids and fatty alcohols, biowaxes, celluloses, and proteins. However, there are few types of gelators that need to be developed urgently, and there are also some problems and shortcomings in existing gelators: for example, proteins are basically water-soluble and can rarely be used directly to produce oleogels. They must be prepared by an emulsion template method, and the process is relatively complicated. In addition, the oil phase is often limited to edible vegetable oils, such as soybean oil, sunflower oil, etc., and the range of choices for the oil phase needs to be expanded, such as essential oils.

[0006] Sodium hydroxide, also known as caustic soda, caustic soda, caustic soda or solid alkali, is a strong base. It is a white solid that is very soluble in water and releases a lot of heat when dissolved. It can also be dissolved in alcohols and some organic solvents.

[0007] The prior art "A mugwort essential oil gel sustained-release system prepared by low-temperature 3D printing" (Qian Xiaoming et al., CN111529561A) discloses a mugwort essential oil gel sustained-release system prepared by low-temperature 3D printing. The preparation process of the system includes the process of printing the mixed solution obtained by mixing the emulsified mugwort essential oil with a polyvinyl alcohol solution by low-temperature 3D printing and cyclically freezing and thawing to prepare a gel sustained-release system. The loss caused by volatilization of mugwort essential oil during the preparation process can be avoided, and its activity can be maintained to the greatest extent.

[0008] The prior art "Transparent essential oil gel and its preparation method" (Ni Yingying et al., CN108113904A) discloses a transparent essential oil gel and its preparation method, wherein the essential oil gel contains the following raw material components in weight percentage: 5-20% essential oil, 5-80% oil, 0.5-5% emulsifier, 1-30% polyol, and 3% water. The essential oil gel prepared by the invention uses the emulsifier sodium subtilisin, which can emulsify the highly polar oil of essential oil very well and form a stable gel, which can be easily applied to aqueous products without the need to add additional solubilizers, and can also increase the soft skin feel of the product.

[0009] The above-mentioned process for preparing essential oil gel is complicated, uses a large number of auxiliary materials, and the essential oil is used as an active ingredient therein, but does not reflect the suggestion that the essential oil can be gelled.

[0010] The prior art "A ligustrazine hydrochloride mint essential oil gel and its preparation method" (Wang Wenping et al., CN118415972A) discloses a ligustrazine hydrochloride mint essential oil gel and its preparation method, using ligustrazine hydrochloride as a gelling agent, and mint essential oil or a solvent system mainly based on mint essential oil as a dispersion medium. However, the above patent only reflects that ligustrazine hydrochloride can gel mint essential oil, and does not reflect the ability to gel other essential oils. Moreover, the amount of ligustrazine hydrochloride used to gel mint essential oil is required to reach 4% (w / w) or more, and the amount of gelling agent used is relatively large.

[0011] It can be seen that we need to screen out a gelling agent that can widely gel essential oils and has better performance and less usage. The essential oil gel of the present invention, in which sodium hydroxide is used as a new essential oil gelling factor, and a system based on essential oils is used as a dispersion medium, a penetration-promoting component and / or an active ingredient, has a simple and efficient process, a low cost, and the resulting gel has stable properties and a wide range of uses. Summary of the invention

[0012] The purpose of the present invention is to provide a high-drug-loaded and stable essential oil gel. The present invention directly uses sodium hydroxide as a gel factor to form a stable gel system with essential oil or a mixed system of essential oil and anhydrous sodium hydroxide ethanol solution.

[0013] The inventors of the present application unexpectedly discovered during the screening of gellable essential oils that a variety of essential oils can be gelled using strong alkalis such as sodium hydroxide and potassium hydroxide in an anhydrous environment. The strong alkali can be added directly as a powder, or dissolved in an anhydrous organic solvent and then directly and evenly dispersed in a variety of essential oils, which then precipitate into gel as the solubility decreases.

[0014] Furthermore, the present application preferably selects the preparation method of the plant essential oil gel, especially selecting technical parameters such as the type of plant essential oil, the type of strong base, the amount of strong base, whether to use anhydrous organic solvent and the amount of anhydrous organic solvent, so as to prepare a more stable gel.

[0015] Without limitation, the inventors believe that the formation of the gel may be related to the physical or chemical interaction between the strong base and some components in the plant essential oil, but it is obviously different from the saponification reaction because the saponification reaction usually requires a higher temperature (e.g. 80°C). If the temperature is low, a longer reaction time (e.g. several weeks to several months) is required, while the technical solution of the present application will form a gel immediately after uniform dispersion.

[0016] Specifically, the present invention provides the following technical solutions: A plant essential oil gel, characterized in that the gel is composed of: 1) plant essential oil, and; 2) a strong base or an anhydrous organic solvent solution of a strong base; The plant essential oil is the matrix and active ingredient, and the strong base is used as the gel factor, the content of the strong base is not less than 1.2% by weight, and the strong base is sodium hydroxide and potassium hydroxide. Preferably, the strong base is sodium hydroxide.

[0017] The gel does not contain water and does not need to be added with other polymer gel materials.

[0018] Furthermore, the plant essential oil is one or more of angelica essential oil, cyperus rotundus essential oil, bupleurum essential oil, peppermint essential oil, Asian mint essential oil, cinnamon oil, eucalyptus oil, sweet orange essential oil, clove leaf essential oil, tea tree essential oil, and lavender essential oil.

[0019] Furthermore, in order to reduce the interference of anhydrous organic solvents on the properties of plant essential oils, the anhydrous organic solvent solution is preferably a saturated solution of a strong base in an anhydrous organic solvent; wherein the anhydrous organic solvent is selected from one or more of anhydrous ethanol, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-diethylacetamide. Preferably, the organic solvent is anhydrous ethanol.

[0020] Furthermore, the gel does not flow down when inverted in a container, or the storage modulus G' of the system is higher than the loss modulus G'' in rheological testing.

[0021] Further, the strong base content is 1.2-5.9% by weight. Preferably, the strong base content is 1.5-3.8%. Most preferably, the strong base content is 1.5%.

[0022] A method for preparing the gel of plant essential oil is characterized by adopting a powder dispersion method or a solution mixing method; the powder dispersion method is to directly add a certain amount of sodium hydroxide powder into the plant essential oil, ultrasonically mix it and then place it to obtain the gel; the solution dispersion method is to dissolve sodium hydroxide in an anhydrous organic solvent, then fully mix it with the plant essential oil and place it to obtain the gel.

[0023] Furthermore, in the powder dispersion method, the strong base content is 1.5-5.9% by weight.

[0024] Furthermore, in the solution mixing method, the strong base content is 1.2-5.9% by weight.

[0025] Furthermore, in order to reduce the interference of the anhydrous organic solvent on the properties of the plant essential oil in the solution mixing method, the anhydrous organic solvent solution is preferably a saturated solution of a strong base in an anhydrous organic solvent; the anhydrous organic solvent is selected from one or more of anhydrous ethanol, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-diethylacetamide. Preferably, the organic solvent is anhydrous ethanol.

[0026] More specifically, the present invention provides an essential oil gel, which is characterized by being composed of sodium hydroxide and a system mainly composed of essential oils, wherein sodium hydroxide serves as a gelling factor, and is prepared by a powder dispersion method or a solution mixing method. In the solution mixing method, sodium hydroxide is fully dissolved in an anhydrous ethanol solution and then uniformly dispersed in the essential oil system to precipitate into a gel.

[0027] The content of sodium hydroxide in the essential oil gel will affect the formation of the essential oil gel. When the sodium hydroxide content is low, a stable gel state cannot be formed. Preferably, the content of sodium hydroxide is greater than or equal to 1.2% by weight of the gel, and the resulting gel has excellent properties.

[0028] More preferably, the content of sodium hydroxide in the powder dispersion method is greater than or equal to 1.5%, and the content of sodium hydroxide in the solvent mixing method is greater than or equal to 1.2%, based on the weight of the gel.

[0029] The essential oil-based system is an organic solvent, essential oil and sodium hydroxide or a mixed system of essential oil and sodium hydroxide, wherein the organic solvent can dissolve the sodium hydroxide well, so that the sodium hydroxide is more evenly dispersed in the essential oil gel.

[0030] Preferably, the organic solvent is one of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-diethylacetamide, and its proportion in the solvent system does not exceed 22% w / w.

[0031] More preferably, the organic solvent is anhydrous ethanol.

[0032] Preferably, auxiliary means such as one or more of ultrasound, high-speed shearing, vortexing, stirring, etc. are used to uniformly mix the strong base in the plant essential oil.

[0033] Preferably, the auxiliary means is ultrasound.

[0034] The essential oil gel preparation method provided by the invention is simple and convenient, and has good reproducibility.

[0035] In summary, the inventors have found through unexpected research that essential oil gel can be prepared by adopting appropriate preparation methods and preferred preparation parameters without adding other gelling factors, and the gel preparation can be formed by itself. No auxiliary materials and special equipment are required in the process of preparing the gel, which saves costs and facilitates large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The appearance pictures (upper row) and micrographs (lower row, magnification 400 times) of Example 1 (A), Example 2 (B), Example 3 (C) and Comparative Example 7 (a) are shown.

[0037] Figure 2: Infrared images of angelica essential oil (a) and angelica essential oil gel (b) in the examples.

[0038] Figure 3 The following are the rheological test results of the angelica essential oil gel in the examples.

[0039] Figure 4 This is the appearance of the essential oil gel in Example 4-17.

[0040] Figure 5 This is the appearance of the essential oil gel in Comparative Examples 1-6.

[0041] Figure 6 Graph showing the physical stability of angelica essential oil (a) and angelica essential oil gel (b) in the examples.

[0042] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. DETAILED DESCRIPTION

[0043] Experiment 1: Sodium hydroxide dispersion method and experiment on whether the gel can contain water.

[0044] Example 1: 6 mg (1.2%) of sodium hydroxide was added to 114 mg of anhydrous ethanol to completely dissolve it; the above solution was mixed with 400 mg of angelica essential oil (anhydrous ethanol: angelica essential oil = 1:3.5, w / w) under ultrasonic conditions (40W, 5 min), and allowed to stand for 5 min to obtain an essential oil gel (see attached Figure 1 -A).

[0045] Example 2: 6 mg of sodium hydroxide (1.5%) was added to 400 mg of angelica essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 1 -B).

[0046] Example 3: 7 mg (1.3%) of sodium hydroxide was added to 133 mg of anhydrous ethanol to completely dissolve it; the above solution was mixed with 400 mg of lavender essential oil (anhydrous ethanol: angelica essential oil = 1:3.0, w / w) under ultrasonic conditions (40W, 5 min) to obtain an essential oil gel (see attached Figure 1 -C).

[0047] Comparative Example 1: 6 mg (1.2%) of sodium hydroxide was added to 114 mg of 95% ethanol to completely dissolve it; the above solution was mixed with 400 mg of angelica essential oil (95% ethanol: angelica essential oil = 1:3.5, w / w) under ultrasonic conditions (40W, 5min) and left for 5min. The resulting mixed system failed to form a gel (see attached Figure 5-1 ).

[0048] The above experimental results show that in anhydrous environment, sodium hydroxide can gel the plant essential oil, and its dispersion method can adopt powder dispersion method or solution mixing method. However, when there is water in the system, gel cannot be formed, such as using 95% ethanol in the comparative example, and essential oil gel cannot be formed.

[0049] Experiment 2: Alkali type selection experiment.

[0050] Examples 1-3: See above.

[0051] Example 4: Take 6 mg of potassium hydroxide (1.5%) and add 400 mg of angelica essential oil. The above solution is fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-1 ).

[0052] Comparative Example 2: 25 mg (5.9%) of berberine hydrochloride was added to 400 mg of angelica essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min). The resulting mixed system failed to form a gel (see attached Figure 5-2 ).

[0053] Comparative Example 3: 25 mg (5.9%) of bamipine hydrochloride was added to 400 mg of angelica essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min). The resulting mixed system failed to form a gel (see attached Figure 5-3 ).

[0054] Comparative Example 4: 25 mg (5.9%) of calcium hydroxide was added to 400 mg of angelica essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min). The resulting mixed system failed to form a gel (see attached Figure 5-4 ).

[0055] Comparative Example 5: 25 mg of sodium carbonate (5.9%) was added to 400 mg of angelica essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min). The resulting mixed system failed to form a gel (see attached Figure 5-5 ).

[0056] Comparative Example 6: 25 mg of sodium bicarbonate (5.9%) was added to 400 mg of angelica essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min). The resulting mixed system failed to form a gel (see attached Figure 5-6 ).

[0057] The above experimental results show that sodium hydroxide and potassium hydroxide as strong bases can meet the requirements for gelling plant essential oils, while weak bases such as calcium hydroxide, sodium carbonate, sodium bicarbonate or other gelling factors such as berberine hydrochloride and bamipine hydrochloride cannot gelate plant essential oils.

[0058] Experiment 3: Experiment on the dosage of sodium hydroxide and the selection of essential oil types.

[0059] Examples 1-3: See above.

[0060] Example 5: 7 mg of sodium hydroxide (1.7%) was added to 400 mg of lavender essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-2 ).

[0061] Example 6: Take 25 mg of sodium hydroxide (5.9%) and add 400 mg of Bupleurum essential oil, and mix the above solution thoroughly under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-3 ).

[0062] Example 7: 9 mg of sodium hydroxide (2.2%) was added to 400 mg of Cyperus rotundus essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-4 ).

[0063] Example 8: 17 mg (4.1%) of sodium hydroxide was added to 400 mg of Asian mint essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-5 ).

[0064] Example 9: Take 10 mg of sodium hydroxide (2.4%) and add 400 mg of cinnamon oil. Mix the solution thoroughly under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-6 ).

[0065] Example 10: Take 10 mg of sodium hydroxide (2.4%) and add 400 mg of clove leaf essential oil. The above solution is fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4 -7).

[0066] Example 11: 15 mg of sodium hydroxide (3.6%) was added to 400 mg of eucalyptus oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4 -8).

[0067] Example 12: 10 mg of sodium hydroxide (2.4%) was added to 400 mg of tea tree essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4 -9).

[0068] Example 13: 16 mg of sodium hydroxide (3.8%) was added to 400 mg of sweet orange essential oil, and the above solution was fully mixed under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-1 0).

[0069] Comparative Example 7: 5.5 mg (1.1%) of sodium hydroxide was added to 104.5 mg of anhydrous ethanol to completely dissolve it; the above solution was mixed with 400 mg of angelica essential oil (anhydrous ethanol: angelica essential oil = 1:3.8, w / w) under ultrasonic conditions (40W, 5 min), and the resulting mixed system failed to form a gel (see attached Figure 1 -a).

[0070] The experimental results show that when the sodium hydroxide content is less than 1.2%, sodium hydroxide cannot gel the plant essential oil, but when the content is greater than or equal to 1.2%, it can form a plant essential oil gel. At the same time, angelica essential oil, cyperus rotundus essential oil, bupleurum essential oil, peppermint essential oil, Asian mint essential oil, cinnamon oil, eucalyptus oil, sweet orange essential oil, clove leaf essential oil, tea tree essential oil, and lavender essential oil can all be used as plant essential oils.

[0071] Experiment 4: Organic solvent type selection experiment.

[0072] Examples 1 and 3: See above.

[0073] Example 14: 6 mg (1.2%) of sodium hydroxide was added to 114 mg of dimethyl sulfoxide to completely dissolve it; the above solution was mixed with 400 mg of angelica essential oil (dimethyl sulfoxide: angelica essential oil = 1:3.5, w / w) under ultrasonic conditions (40W, 5 min) to obtain an essential oil gel (see attached Figure 4-1 1).

[0074] Example 15: 6 mg (1.2%) of sodium hydroxide was added to 114 mg of N-methylpyrrolidone to completely dissolve it; the above solution was mixed with 400 mg of angelica essential oil (N-methylpyrrolidone: angelica essential oil = 1:3.5, w / w) under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-1 2).

[0075] Example 16: 6 mg (1.2%) of sodium hydroxide was added to 114 mg of N,N-dimethylformamide to completely dissolve it; the above solution was mixed with 400 mg of angelica essential oil (N,N-dimethylformamide: angelica essential oil = 1:3.5, w / w) under ultrasonic conditions (40W, 5 min) to obtain an essential oil gel (see attached Figure 4-1 3).

[0076] Example 17: 6 mg (1.2%) of sodium hydroxide was added with 114 mg of N, N-diethylacetamide to completely dissolve it; the above solution was mixed with 400 mg of angelica essential oil (N, N-diethylacetamide: angelica essential oil = 1:3.5, w / w) under ultrasonic conditions (40W, 5 min) to obtain essential oil gel (see attached Figure 4-1 4).

[0077] The above results show that when the anhydrous organic solvent of the present invention is anhydrous ethanol, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, or N,N-diethylacetamide, sodium hydroxide can be fully dispersed in the plant essential oil to effectively form an essential oil gel.

[0078] Example 18: Infrared images of angelica essential oil (a) and angelica essential oil gel (b): Take the angelica essential oil gel and add an appropriate amount of KBr to grind and press the angelica essential oil into a tablet. Apply the angelica essential oil evenly on the KBr tablet and measure the infrared spectrum of 4000-400 cm-1 using a Fourier transform infrared spectrometer. -1 Infrared absorption in the range, the results are shown in Figure 2 . Figure 2 The results showed that the infrared spectra of the two were almost identical and the main characteristic peaks had no obvious changes, indicating that no chemical changes occurred after gelation, that is, saponification reaction could not occur.

[0079] Example 19: Characterization of the properties of angelica essential oil gel: The angelica essential oil gel obtained in Example 1 was added to a rheometer for testing. The results are shown in Figure 3 The gel parameters are: the ratio of storage modulus G' to loss modulus G'' is 4.

[0080] Example 20: Stability of Angelica essential oil gel: Take 1g of Angelica essential oil gel and Angelica essential oil obtained in Example 1, place at room temperature, and measure their weight loss rates at 12h, 24h, 36h, 48h, and 60h. Figure 6 , indicating that the essential oil made into gel can effectively reduce the volatilization loss of angelica essential oil.

Claims

1. A gel of plant essential oil, characterized in that: The gel is composed of: 1) plant essential oil, and; 2) strong alkali or anhydrous organic solvent solution of strong alkali; wherein the plant essential oil is the matrix and active ingredient, the strong alkali is used as a gelling factor, the content of the strong alkali is not less than 1.2% by weight, and the strong alkali is sodium hydroxide and potassium hydroxide; the gel does not contain water and does not need to add other polymer gel materials.

2. The gel of plant essential oil according to claim 1, characterized in that: The plant essential oil is one or more of angelica essential oil, cyperus rotundus essential oil, bupleurum essential oil, peppermint essential oil, Asian mint essential oil, cinnamon oil, eucalyptus oil, sweet orange essential oil, clove leaf essential oil, tea tree essential oil, and lavender essential oil.

3. The gel of plant essential oil according to claim 1, characterized in that: The anhydrous organic solvent solution is a saturated solution of a strong base in an anhydrous organic solvent; the anhydrous organic solvent is one or more selected from anhydrous ethanol, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-diethylacetamide.

4. The gel of plant essential oil according to claim 1, characterized in that: The gel does not flow down when inverted in a container, or the storage modulus G' of the system is higher than the loss modulus G'' in rheological testing.

5. The gel of plant essential oil according to claim 1, characterized in that: The strong base content is 1.2-5.9% by weight.

6. A method for preparing a gel of plant essential oil according to claim 1, characterized in that: The preparation method is a powder dispersion method or a solution mixing method; the powder dispersion method is to directly add a certain amount of sodium hydroxide powder into the plant essential oil, ultrasonically mix it and then leave it to obtain the product; the solution dispersion method is to dissolve the sodium hydroxide in an anhydrous organic solvent, then fully mix it with the plant essential oil and leave it to obtain the product.

7. The method for preparing the gel of plant essential oil according to claim 6, characterized in that: The content of the strong base in the powder dispersion method is 1.5-5.9% by weight.

8. The method for preparing the gel of plant essential oil according to claim 6, characterized in that: In the solution mixing method, the strong base content is 1.2-5.9% by weight.

9. The method for preparing the gel of plant essential oil according to claim 6, characterized in that: The anhydrous organic solvent in the solution mixing method is one or more selected from anhydrous ethanol, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-diethylacetamide.

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