Preparation method of astragalus mongholicus nanoemulsion

Abstract

The invention relates to the technical field of traditional Chinese medicinal material processing, and discloses a preparation method of radix astragali nanoemulsion, which comprises the following steps: step 1, extracting radix astragali fat-soluble extract by supercritical extraction; 2, extracting the astragalus membranaceus subjected to supercritical extraction with water to obtain a water-soluble astragalus membranaceus extract; step 3, adding lecithin into the astragalus membranaceus fat-soluble extract, and heating to obtain a system I; 4, diluting the astragalus membranaceus water-soluble extract, heating, shearing by using a microtube jet high-shear mixer, and homogenizing by using a high-pressure microjet homogenizer to obtain a system II; and step 5, centrifuging the system II, taking supernate, adding water, shearing by using a micro-tube jet high-shear mixer, adding Tween 80, adding the system I while shearing, continuously shearing and uniformly mixing, and performing micro-emulsification by using a high-pressure micro-jet homogenizer to obtain the astragalus mongholicus nano-emulsion. According to the method, the extraction of full-functional components of the astragalus membranaceus can be realized, and the effective components of the astragalus membranaceus are fully utilized in a form of preparing the nano-emulsion.

Description

Technical Field

[0001] The invention relates to the technical field of Chinese medicinal material processing, and in particular to a method for preparing an astragalus nanoemulsion. Background Art

[0002] Astragalus is sweet and slightly warm. It has the effects of replenishing qi and strengthening the exterior, promoting diuresis and expelling toxins, draining pus, and healing sores and promoting tissue regeneration. It is a commonly used qi-replenishing medicine in clinical practice. Astragalus was first recorded in Shennong's Herbal Classic and was listed as a top-grade medicine. It is known as the "best qi-replenishing medicine". It has attracted much attention from experts and scholars at home and abroad due to its rich chemical components and powerful pharmacological effects. The main chemical components of Astragalus are polysaccharides, saponins, flavonoids, proteins, cellulose and trace elements. The content of polysaccharides in Astragalus is 48.8 mg / g, the content of total flavonoids in Astragalus is 47.4 mg / g, and the content of astragaloside saponins is relatively low, about 0.13-1.53 ​​mg / g. The flavonoid compounds isolated from Astragalus include flavonoids, isoflavones, isoflavanes and pteranodones. Among them, calycosin, 5-hydroxycalycosin and formononetin and their aglycones have significant effects in immune system regulation, anti-oxidation, anti-apoptosis and other aspects. One of the main active ingredients of astragaloside is astragaloside IV, which has the functions of regulating body metabolism and immune function. The price of astragaloside IV in astragalus extract is 5-10%, and the price is 1300-2600 yuan / kg, 30%-40% is more than 8000 yuan / kg, and more than 90% is as high as 160,000-300,000 yuan / kg. In the production process of astragalus, some scraps and waste are inevitably produced. Through extraction technology, the scraps and waste can be crushed and extracted to make effective raw materials for sale, which can increase the added value of the product and maximize the utilization rate of raw materials. At the same time, it can transform astragalus from a relatively low-gross-profit medicinal material into a high-gross-profit food raw material with medicinal and edible properties, thereby increasing the profits of the enterprise.

[0003] At present, the extraction methods of Astragalus include water extraction, alcohol precipitation, enzymatic method, ultrasound and other methods. In the process of extraction, the temperature is too high, which destroys some thermally unstable components and reduces the content and type of the extracted effective components, or the extraction agent (ethanol, methanol, methane, etc.) is added. The extract is applied to food, which does not comply with national laws and regulations, and there are potential safety hazards. The applicable industry scope is limited, which is not conducive to industrial production. Therefore, it is of great significance to develop a new extraction technology for the effective components of Astragalus and improve the bioavailability of Astragalus extract. Summary of the invention

[0004] The present invention aims to provide a method for preparing an astragalus nanoemulsion to improve the extraction effect and bioavailability of an astragalus extract.

[0005] To achieve the above object, the present invention adopts the following technical scheme: a method for preparing astragalus nanoemulsion, characterized in that it comprises the following steps:

[0006] Step 1, preparation of fat-soluble extract of Astragalus: extracting fat-soluble extract of Astragalus by supercritical extraction technology;

[0007] Step 2, preparation of water-soluble extract of Astragalus: extracting the Astragalus after supercritical extraction with water, and concentrating it into an extract to obtain a water-soluble extract of Astragalus;

[0008] Step 3, adding lecithin to the fat-soluble extract of Astragalus membranaceus, and heating the mixture to obtain System I;

[0009] Step 4: dilute the water-soluble extract of Astragalus membranaceus with water, heat it, shear it with a microtube jet high shear mixer, and then homogenize it with a high-pressure microjet homogenizer to obtain System II;

[0010] Step 5: Centrifuge system II, take the supernatant and add water, shear it with a microtube jet high shear mixer, add Tween 80, add system I while high-speed shearing, continue shearing and mixing, and then use a high-pressure microfluidizer to micro-emulsify to obtain Astragalus nanoemulsion.

[0011] Preferably, as an improvement, in step one, when supercritical extraction technology is used to extract the fat-soluble extract of Astragalus, the moisture content of the Astragalus raw material is controlled at 6%, and the extraction conditions are: extraction pressure 20-40MPa, temperature 20-60°C, separation kettle 1 temperature 20-60°C, separation kettle 1 pressure 5-15Mpa, separation kettle 2 temperature 10-40°C, separation kettle 2 pressure 1-6Mpa, and extraction time is 0.5-5h.

[0012] Preferably, as an improvement, in step 2, the solid-liquid ratio during water extraction is 1:5-1:15, and the number of extractions is 1-3 times.

[0013] Preferably, as an improvement, in step three, the mass ratio of lecithin to the fat-soluble extract of Astragalus is 1:1-1:10, lecithin is added when the temperature rises to 40-60°C, and then the temperature continues to rise to 50-70°C.

[0014] Preferably, as an improvement, in step 4, the mass ratio of the Astragalus water extract to water is 1:5-1:10.

[0015] Preferably, as an improvement, in step 4, the heating temperature is 40-90°C.

[0016] Preferably, as an improvement, in step 4, the shearing time is 1-30 min, and the rotation speed is 5000-30000 rpm.

[0017] Preferably, as an improvement, in step 4, a diamond interaction chamber is used for homogenization 1-10 times, and the models of the diamond interaction chamber are H30Z, H10Z, F20Y, and F12Y; then centrifugation is performed, and the centrifugal speed is 1000-6000rpm and the centrifugal time is 5-30min.

[0018] Preferably, as an improvement, in step five, the centrifugal speed is 1000-6000rpm, and the centrifugal time is 5-30min; then the supernatant is taken and water is added to the supernatant, the mass ratio of supernatant to water is 1:1-8:1, and then high-speed shearing is used for pre-emulsification, the shearing time is 1-30min, and the speed is 5000-30000rpm; Tween 80 is added during the shearing process, and the mass ratio of Tween 80 to the supernatant is 1:5-1:20, and the pre-emulsified liquid is homogenized and emulsified with a high-pressure microfluidizer, and homogenized using a diamond interactive cavity combination of F20Y and F12Y, and the cycle is 1-10 times.

[0019] Preferably, as an improvement, an Astragalus nanoemulsion has an average particle size of 10-200 nm.

[0020] The principle and advantage of this scheme are: in actual application, in this technical scheme, in conventional astragalus extraction, water extraction can only extract water-soluble components. If fat-soluble components are to be extracted, organic solvents such as ethanol must be used, which will cause organic matter residues and affect product quality. The method of combining supercritical extraction with water extraction is adopted to realize the extraction of all effective components of water-soluble components and fat-soluble components of astragalus. Entrainment agents are not used in the extraction process, and there is no organic residue. Under the action of ultra-high pressure, some intermolecular forces will weaken or break, so that some macromolecular substances will become substances with smaller molecular weight after breaking bonds. At the same time, cavitation effect is produced, so that some cells are broken, and the effective components in the cells are freed, thereby improving the extraction rate of effective components. Then, NanoGenizer 30K high-pressure microfluidizer technology was used, with the extract of Astragalus membranaceus water extract as the aqueous phase and the fat-soluble extract of Astragalus membranaceus as the oil phase. Emulsifiers such as lecithin and Tween 80 were added. The mixture was first pre-emulsified by a microtube jet high-shear mixer, and then nano-emulsified by a NanoGenizer 30K high-pressure microfluidizer. This resulted in an emulsion containing all the effective ingredients of Astragalus membranaceus, with an average particle size between 10 and 200 nm.

[0021] Nanoemulsion technology is a new type of drug preparation technology, which belongs to a type of nanotechnology. This small size effect directly solves many problems that traditional technologies cannot solve. Nanoemulsion, also known as ultrafine emulsion, is a stable, transparent, low-viscosity dispersion system formed by water, oil, surfactants and co-surfactants in appropriate proportions. Nanoemulsions can be divided into three types: oil-in-water nanoemulsions (O / W), water-in-oil nanoemulsions (W / O) and bicontinuous nanoemulsions. The droplet size is generally below 100nm. Compared with ordinary emulsions, nanoemulsions are transparent or almost transparent dispersion systems with good fluidity. Ordinary emulsion particles are larger, the dispersed phase particles are larger, and they are easy to settle and separate. The molecules mainly rely on van der Waals forces, while nanoemulsion particles are smaller and have ultra-low interfacial tension. The particles rely on their own charges to interact with each other, and the force between charges is stronger than van der Waals forces. Conventional emulsion is a thermodynamically unstable system. Its preparation requires external energy such as stirring, homogenization, ultrasonic grinding, and colloid milling. If it is left for too long, the hydrogen bond effect will be greatly weakened, and then the molecules will polymerize and eventually split into oil and water. However, nanoemulsion is a thermodynamically stable system that can be generated by itself without any external intervention. It can solubilize a large amount of water- and oil-insoluble substances in a specific area while maintaining the stability of its properties.

[0022] However, most of the nanoemulsion processes are prepared by the emulsification of high-speed emulsifiers. The equipment investment and the process requirements for the emulsification process are high. In addition, the market price of the surfactant itself is not low. The surfactant content in the actual nanoemulsion stock solution can account for between 18% and 36%. These costs add up to a high market price for drugs, which has caused certain difficulties in promotion. In addition, the nanoscale microemulsion system has the characteristics of porosity, large specific surface area, and weak light scattering. Therefore, it has many uses in the chemical industry, such as cosmetics, biomedicine, cleaning, oil extraction, solubilization, nanomaterial preparation templates, drug encapsulation and delivery, detoxification, etc. Nanoemulsion also has the characteristics of being able to be made into a gel-shaped rheological material, as well as the function of encapsulating drugs, so that it can encapsulate lipophilic active ingredients, and the research heat in the medical field is also rising.

[0023] At present, nanoemulsion technology is rarely used in Chinese herbal medicine extracts, and only a few reports have been made on its application in monomeric effective ingredients extracted from Chinese herbal medicines. The main reason is that the chemical composition of Chinese herbal medicine extracts is complex, and nanoemulsions may have physical or chemical stability problems during long-term storage, such as particle aggregation, phase separation or component degradation. In the process of preparing nanoemulsions in this technical solution, the selection of surfactants is one of the difficulties and key points of this technical solution. It requires both high interfacial adsorption rate and good interfacial activity to reduce the degree of aggregation and stabilize the nanoemulsion; at the same time, it is also necessary to consider whether it has biological toxicity and does not affect the biological effects and biocompatibility of the nanoemulsion. The surfactants used in this technical solution are phospholipids and Tween 80. Phospholipids are considered to be a natural and safe emulsifier. Its molecules have hydrophobic fatty acid chains and hydrophilic phosphate groups. This amphiphilicity enables it to effectively reduce interfacial tension at the oil-water interface, promote oil-water mixing, form a stable emulsified system, and prevent droplet aggregation and stratification. At the same time, phospholipids are an important component of cell membranes, have good biodegradability and biocompatibility, are harmless to the human body, and can be metabolized normally by the human body. Tween 80 is compatible with various types of oils and surfactants, and can play a synergistic effect with phospholipids, effectively reducing the surface tension of the oil-water interface, allowing oil droplets to disperse in water to form a stable emulsion. The combined use of the two emulsifiers can effectively improve the stability of the emulsion and avoid stratification caused by instability of the emulsion system.

[0024] In addition, the technical solution optimizes the formation process of nanoemulsion, adopts high-pressure micro-jet technology, and the NanoGenizer 30K high-pressure micro-jet homogenizer is equipped with a cooling circulation system. The material passes through the special diamond micro-channels (Y-type and Z-type) of the interactive cavity with a hydraulic pressure of less than 200Mpa, forming a strong shear, impact and cavitation effect of the supersonic jet, emulsifying and dispersing the particles in the liquid at the nano level. At the same time, in order to ensure the stability of the dispersion, we need to cool the material, connect cooling water at the heat exchange jacket, and the material passes through the internal pipeline. The cooling water physically cools it outside. This process can avoid the degradation of the effective ingredients in the material due to high temperature. The astragalus nanoemulsion formed by this technology has undergone an accelerated stability test. After the emulsion is centrifuged (4000rpm / min, 5h), there is no stratification, demulsification and other phenomena, and the system is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron micrograph of the raw medicinal material of Astragalus membranaceus in the examples of the present invention (control group and supercritical treatment group).

[0026] Figure 2 The scanning electron microscope image of the raw medicinal material powder of Astragalus membranaceus in the examples of the present invention (control group and supercritical treatment group).

[0027] Figure 3 Graph showing particle size of Astragalus nanoemulsion in the examples of the present invention (control group and treatment group).

[0028] Figure 4 The results of the stability test of the Astragalus nanoemulsion in the examples of the present invention are shown.

[0029] Figure 5 Flow chart of the experimental treatment of Astragalus nanoemulsion in the embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following is further described in detail through specific implementations, but the implementation of the present invention is not limited thereto. Unless otherwise specified, the technical means used in the following implementations are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents, etc. used can all be obtained from commercial channels.

[0031] Example 1

[0032] A method for preparing an astragalus nanoemulsion comprises the following steps:

[0033] Step 1, preparation of fat-soluble extract of Astragalus membranaceus, controlling the moisture content of sliced ​​Astragalus membranaceus raw medicinal material to 6%, loading into an extraction tank, and extracting under supercritical technology; extraction conditions: extraction pressure 35MPa, temperature 50°C, separation kettle 1 temperature 50°C, separation kettle 1 pressure 15Mpa, separation kettle 2 temperature 35°C, separation kettle 2 pressure 5.7Mpa, extraction time 3h, then collecting the separated material to obtain fat-soluble extract I of Astragalus membranaceus;

[0034] Step 2, preparation of water-soluble extract of Astragalus membranaceus, taking out the Astragalus membranaceus extracted by supercritical extraction from the extraction kettle, adding 10 times of water, boiling and extracting twice, centrifuging to remove residue, combining the two clear liquids and concentrating under reduced pressure to obtain a water-soluble extract of Astragalus membranaceus with a water content of 40-70%;

[0035] Step 3: After heating the fat-soluble extract of Astragalus to 55° C., lecithin is added thereto and heated and stirred until the temperature reaches 70° C. to obtain system I; the mass ratio of lecithin to the fat-soluble extract of Astragalus is 4:5;

[0036] Step 4: Add water to the Astragalus membranaceus water extract to dilute it, heat it to 70°C, shear it with a microtube jet high shear mixer for 5 minutes to mix it, and then homogenize it with a NanoGenizer 30K high-pressure microfluidizer, first cycle it with an F20Y diamond interactive dissolution chamber for 5 times, and then cycle it with an F12Y diamond interactive dissolution chamber for 5 times; then centrifuge it, the centrifugation parameters are: 4000rpm / min, 10min, remove the supernatant and add water, the mass ratio of supernatant to water is 1:7, and obtain system II;

[0037] Step 5, the system II is heated to 70 ° C, and then sheared with a microtube jet high shear mixer, Tween 80 is slowly added during the shearing process (the mass ratio of Tween 80 to the supernatant is 1:20), and then the above system I is continued to be added during the shearing process, the shearing time is 5 minutes, and finally directly micro-emulsified with a high-pressure microfluidizer, cyclically emulsified 5 times with an F20Y diamond interactive cavity, and then cyclically emulsified 5 times with an F12Y diamond interactive cavity to obtain an Astragalus nanoemulsion.

[0038] Example 2

[0039] The difference between this embodiment and embodiment 1 is that: in this embodiment, in step 1, the extraction conditions are: extraction pressure 20MPa, temperature 60°C, separation kettle 1 temperature 20°C, separation kettle 1 pressure 15Mpa, separation kettle 2 temperature 10°C, separation kettle 2 pressure 6Mpa, and extraction time 5h. In step 3, the mass ratio of lecithin to fat-soluble extract of astragalus is 1:1; in step 5, the mass ratio of Tween 80 to supernatant is 1:5.

[0040] Example 3

[0041] The difference between this embodiment and embodiment 1 is that: in this embodiment, in step 1, the extraction conditions are: extraction pressure 40MPa, temperature 20°C, separation kettle 1 temperature 60°C, separation kettle 1 pressure 5Mpa, separation kettle 2 temperature 40°C, separation kettle 2 pressure 6Mpa, and extraction time 0.5h. In step 3, the mass ratio of lecithin to fat-soluble extract of astragalus is 1:10; in step 5, the mass ratio of Tween 80 to supernatant is 1:10.

[0042] Experimental Example 1 Scanning electron microscope

[0043] The original Astragalus membranaceus (block and powder) without supercritical treatment (control group) and after supercritical treatment (treatment group) were subjected to scanning electron microscopy at 300, 500, 1000, and 2000 times. The results are as follows Figure 1-2 As shown in the figure: The original medicinal materials of Astragalus (block, powder) without supercritical treatment (control group) and after supercritical treatment (treatment group) were subjected to scanning electron microscopy at 300, 500, 1000, and 2000 times. The results showed that the surface of the control group samples was flatter, tighter, smoother, more uniform, without impurities, regular in shape, dense in cross section, with fewer tiny holes and smaller gaps. The treatment group showed irregular shapes and shapes of different sizes, loose structure, rough surface, holes, and a loose porous structure has been formed, the pores and tube diameters have become larger, and the passages have become wider. After supercritical treatment, under the action of ultra-high pressure, some intermolecular forces will be weakened or broken, so that some macromolecular substances will become substances with smaller molecular weight after breaking bonds, making their gaps larger, which is conducive to improving the extraction rate of effective ingredients.

[0044] Experimental Example 2 Supercritical Extraction of Astragalus

[0045] The moisture content of the sliced ​​Astragalus raw medicinal material is controlled at 6%, and the material is loaded into an extraction tank and extracted under supercritical technology; the extraction conditions are: extraction pressure 35MPa, temperature 50°C, separation kettle 1 temperature 50°C, separation kettle 1 pressure 15Mpa, separation kettle 2 temperature 35°C, separation kettle 2 pressure 5.7Mpa, extraction time 3h, and then the isolate is collected to obtain the Astragalus fat-soluble extract.

[0046] The fat-soluble extracts of Astragalus were collected, and the total flavonoids and total saponins in the original medicinal materials of Astragalus, the original medicinal materials after supercritical extraction of Astragalus, and the fat-soluble extracts of Astragalus were tested. The test results are shown in Table 1.

[0047] Table 1 Astragalus efficacy ingredients

[0048] Astragalus membranaceus after supercritical treatment Astragalus water soluble extract Astragalus fat-soluble extract Total flavonoids (%) 0.412 0.286 13.4 Total saponins (%) 0.274 0.167 9.73

[0049] Table 2 Yield of Astragalus Extract

[0050] Astragalus membranaceus after supercritical treatment Astragalus water soluble extract Astragalus fat-soluble extract Weight(g) 1000 330 20 Yield (%) 100 33.0 2

[0051] According to the test results, after supercritical extraction, the total flavonoids and total saponins of Astragalus are basically extracted. The fat-soluble extract of Astragalus is used as the oil phase, an emulsifier is added, and nano-level emulsification is performed through the NanoGenizer 30K high-pressure microfluidizer equipment to obtain an emulsion containing all the effective ingredients of Astragalus. The average particle size is between 10 and 200 nm, thereby achieving full utilization of the effective ingredients of Astragalus.

[0052] Experimental Example 3 Preparation and Stability Test of Astragalus Nanoemulsion

[0053] Experimental design:

[0054] ① Mother solution group: 10% Astragalus membranaceus water extract was diluted 7 times to obtain the mother solution ( Figure 4 Left).

[0055] ② Optimized formula group: After the Astragalus water extract was diluted 7 times, homogenized and centrifuged, the formula group was obtained according to the following mass percentage ratio: supernatant 58% + 19% water + 3% Tween + 10% Astragalus fat-soluble extract + 8% phospholipids + 2% glycerol.

[0056] ③Nanoemulsion treatment group:

[0057] Step 1: Preparation of oil phase

[0058] Weigh 10 g of the fat-soluble extract of Astragalus membranaceus and heat it to 55° C. in a beaker with magnetic stirring, then add 8 g of phospholipids to the fat-soluble extract of Astragalus membranaceus and continue to stir magnetically until it is uniform.

[0059] Step 2: Preparation of Astragalus Nanoemulsion

[0060] The water extract of Astragalus membranaceus was diluted 7 times, homogenized with a diamond interactive chamber (F20Y, F12Y), centrifuged, and the precipitate was discarded. 58 g of the extract was added with 19 g of water, 3 g of Tween, and 2 g of glycerol, heated to mix, and slowly added with the above to prepare the oil solution. After shearing for 5 minutes, a microemulsification test was carried out using a microfluidizer (model F20Y and F12Y diamond interactive chamber), and the test was repeated five times.

[0061] The experimental processing steps are as follows Figure 5 shown.

[0062] Experimental methods:

[0063] Detection method of mother liquor and astragalus nanoemulsion particle size: Take 100 μL of the mother liquor and the prepared astragalus nanoemulsion, dilute 100 times, and show a bright fluorescent feeling. Take an appropriate amount of sample and use the Nicomp series nanoparticle size analyzer. This series of instruments uses the dynamic light scattering (DLS) principle to measure the particle size distribution of nanoparticles.

[0064] Experimental results:

[0065] The particle size test results of Astragalus nanoemulsion are as follows Figure 3 As shown ( Figure 3 The left is the mother solution control group. Figure 3 The right is the Astragalus nanoemulsion treatment group): The results show that the particle size of the sample mother liquid is 1077.2nm. The particle size distribution diagram shows that there are particles of different sizes in the sample, ranging from 100nm to 10000nm. The distribution has a wide particle size range and lacks an obvious central trend, which indicates that the particle size distribution of the sample is uneven.

[0066] After emulsification treatment, the particle size is 57.0nm. The particle size analysis results show that the particle size distribution range of the sample is narrow, and most of the particles are concentrated between 20nm and 100nm, showing a single peak mode with an obvious peak value, indicating that the size distribution of particles in the sample is very consistent, indicating that the particle size distribution is highly uniform.

[0067] The stability test results of Astragalus nanoemulsion are as follows Figure 4 As shown ( Figure 4 The left is the mother liquor, Figure 4 Astragalus nanoemulsion, Figure 4 The right side shows the Tyndall effect of Astragalus nanoemulsion after dilution 100 times): The results show that the sample has good fluidity, no wall adhesion during shaking, and no precipitation, stratification or other demulsification phenomena after centrifugation (4000rpm / min, 5h). Figure 4 After adding water to dilute 100 times, it shows the Tyndall effect under parallel light (such as Figure 4 As shown on the right, the emulsion system is stable and can be used as the final formula for mass production.

[0068] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing an astragalus nanoemulsion, characterized in that: The steps include: Step 1, preparation of fat-soluble extract of Astragalus: extracting fat-soluble extract of Astragalus by supercritical extraction technology; Step 2, preparation of water-soluble extract of Astragalus: extracting the Astragalus after supercritical extraction with water, and concentrating it into an extract to obtain a water-soluble extract of Astragalus; Step 3, adding lecithin to the fat-soluble extract of Astragalus membranaceus, and heating the mixture to obtain System I; Step 4: dilute the water-soluble extract of Astragalus membranaceus with water, heat it, shear it with a microtube jet high shear mixer, and then homogenize it with a high-pressure microjet homogenizer to obtain System II; Step 5: Centrifuge system II, take the supernatant and add water, shear it with a microtube jet high shear mixer, add Tween 80, add system I while high-speed shearing, continue shearing and mixing, and then use a high-pressure microfluidizer to micro-emulsify to obtain Astragalus nanoemulsion.

2. The method for preparing an astragalus nanoemulsion according to claim 1, characterized in that: In step 1, when supercritical extraction technology is used to extract the fat-soluble extract of Astragalus, the moisture content of the Astragalus raw material is controlled at 6%, and the extraction conditions are: extraction pressure 20-40MPa, temperature 20-60°C, separation kettle 1 temperature 20-60°C, separation kettle 1 pressure 5-15Mpa, separation kettle 2 temperature 10-40°C, separation kettle 2 pressure 1-6Mpa, and extraction time is 0.5-5h.

3. The method for preparing an astragalus nanoemulsion according to claim 2, characterized in that: In step 2, the solid-liquid ratio during water extraction is 1:5-1:15, and the number of extractions is 1-3 times.

4. The method for preparing an astragalus nanoemulsion according to claim 3, characterized in that: In step three, the mass ratio of lecithin to the fat-soluble extract of Astragalus is 1:1-1:10, lecithin is added when the temperature rises to 40-60°C, and then the temperature continues to rise to 50-70°C.

5. The method for preparing an astragalus nanoemulsion according to claim 4, characterized in that: In step 4, the mass ratio of the astragalus water extract to water is 1:5-1:

10.

6. The method for preparing an astragalus nanoemulsion according to claim 5, characterized in that: In step 4, the heating temperature is 40-90°C.

7. The method for preparing an astragalus nanoemulsion according to claim 6, characterized in that: In step 4, the shearing time is 1-30 min, and the rotation speed is 5000-30000 rpm.

8. The method for preparing an Astragalus nanoemulsion according to claim 7, characterized in that: In step 4, a diamond interaction chamber is used for homogenization 1-10 times, and the model of the diamond interaction chamber is H30Z, H10Z, F20Y or F12Y; then centrifugation is performed, and the centrifugal speed is 1000-6000rpm, and the centrifugal time is 5-30min.

9. The method for preparing an Astragalus nanoemulsion according to claim 9, characterized in that: In step five, the centrifugal speed is 1000-6000rpm, and the centrifugal time is 5-30min; then the supernatant is taken and water is added to the supernatant, the mass ratio of the supernatant to water is 1:1-8:1, and then high-speed shearing is performed, the shearing time is 1-30min, and the speed is 5000-30000rpm; Tween 80 is added during the shearing process, and the mass ratio of Tween 80 to the supernatant is 1:5-1:20, and the high-pressure microfluidizer is used for homogenization and emulsification, and the diamond interactive cavity combination using F20Y and F12Y is used for homogenization, and the cycle is 1-10 times.

10. The Astragalus nanoemulsion prepared by the method for preparing an Astragalus nanoemulsion according to any one of claims 1 to 9, characterized in that: The average particle size is 10-200nm.

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