A method for preparing natural borneol for increasing the yield of dextrorotatory borneol

Abstract

The present application provides a method for preparing natural borneol for increasing the yield of d-borneol, the method comprising the step of stacking borneol camphor to sweat. The present application adopts a direct stacking sweating method that fits the local environment, does not require drying or boiling, does not require plastic film covering, and minimizes energy loss; does not use organic solvents to extract natural borneol, and uses a water vapor distillation method combined with ultrasound-assisted extraction, which is green and pollution-free; at the same time, the method of the present application can also effectively increase the yield of d-borneol.

Description

Field of the Invention

[0001] The present application belongs to the field of natural medicine and traditional Chinese medicine preparation. Specifically, the present application provides a method for preparing natural borneol for increasing the yield of dextrorotatory borneol. Background Art

[0002] Cinnamomum camphora (L.) Presl is one of the main raw materials for extracting natural borneol (dextrorotatory borneol). Fresh borneol leaves and branches are extracted by steam to obtain crude extracts, which are then refined to obtain natural borneol. Natural borneol has the effects of invigorating the mind, clearing away heat and relieving pain. It is mainly used to treat fever, coma, red eyes, mouth sores, sore throat, pus in the ear canal and other symptoms.

[0003] At present, ultrasound-assisted extraction technology is widely used for the extraction of volatile components of plants. Ultrasonic extraction uses the cavitation and diffusion effects of ultrasound to destroy cell walls and accelerate the dissolution of active ingredients. Compared with traditional extraction methods, polysaccharides, phenols, flavonoids and other substances extracted based on ultrasound have higher yields and more stable activities. Different extraction methods combined with ultrasonic extraction have become a research hotspot for the extraction of volatile components of plants. On the one hand, the combination of multiple methods can improve its extraction rate, and on the other hand, it can solve the problem of high energy consumption required by the single method to a certain extent. At present, most industrial production of natural borneol uses steam distillation to directly extract raw materials, and rarely pre-treats the raw materials. At present, the published patents related to natural borneol are mostly concentrated on the innovation of extraction and refining devices, the development of daily chemical products and clinical applications. There are very few Chinese patents on the pretreatment of borneol camphor. On the one hand, there is a patent (Chinese patent: CN110003983A) to dry and crush the raw materials of borneol camphor, and then use organic solvent impregnation combined with ultrasound to assist in the extraction of borneol essential oil. However, this patent has problems such as high cost and environmental pollution. On the other hand, the use of composite enzymes to enzymatically hydrolyze the crushed borneol camphor can also increase the yield of natural borneol (such as Chinese patent: CN108484362A), but there are problems such as high production cost, great influence by enzyme activity, and unstable yield. Therefore, it is particularly necessary to provide a low-cost, green and safe method for preparing natural borneol.

[0004] "Sweating" is a green and low-energy traditional processing method. It is to pile up fresh medicinal materials or heated medicinal materials after cleaning and sweating, so that the moisture contained in the medicinal materials will evaporate to the surface. This traditional processing method summarized by the people's long-term production and life was discussed as early as "Qianjin Yifang": "The medicine is not taken by drying in the shade or exploding. Although it has a name, it is not a real medicine." After modern application and development, it is often used for the processing of non-volatile Chinese medicinal materials such as Poria cocos, Sichuan Dipsacus asper, Atractylodes macrocephala, Rehmannia glutinosa, and volatile Chinese medicinal materials such as Patchouli, but there is no sweating research on borneol camphor. Studies have shown that the chemical composition of some Chinese medicinal materials will change to a certain extent during the "sweating" process. The ineffective components and effective components in the Chinese medicinal materials can be transformed into each other by affecting the precursor compounds, thereby increasing the content of active ingredients in the Chinese medicinal materials.

[0005] Natural borneol has antibacterial, antiviral, and antioxidant effects, and is widely used in the fields of medicine, daily chemicals, etc. However, the State Food and Drug Administration and relevant departments in Europe and the United States have clearly prohibited the addition of artificial synthetic borneol in medicine, food and other related products, so that the demand for the use of natural borneol will be greatly increased, and the market prospects are also very considerable. my country's natural borneol resources are in short supply, the domestic demand is large, and natural borneol still needs to be imported. It is particularly necessary to increase the output of natural borneol through a method. In view of the above problems, the present invention optimizes the various parameters of borneol camphor sweating, airing, ultrasound and water vapor extraction, and preferably obtains a natural borneol preparation method that is pollution-free and can increase the output of right-handed borneol. Summary of the invention

[0006] In order to solve the above problems, a simple, easy and low-cost method for preparing natural borneol for increasing the yield of dextrorotatory borneol is provided:

[0007] On the one hand, the present application provides a method for preparing natural borneol for increasing the yield of d-borneol, the method comprising the step of stacking borneol camphor to induce sweating.

[0008] Furthermore, the method comprises the following steps:

[0009] (1) Cleaning and selecting medicinal materials: remove impurities such as mud, sand, and insect eggs from fresh camphor;

[0010] (2) Sweating: Pile the cleaned camphor camphor to sweat, and control the temperature, humidity and time of sweating in the dark;

[0011] (3) Raw material pretreatment: wash the borneol camphor after sweating with water, dry it in the shade and then crush it;

[0012] (4) Ultrasound: Add the crushed borneol camphor to the solvent and perform ultrasound.

[0013] (5) Extraction: The borneol camphor after ultrasonic treatment is transferred to an extraction device for steam distillation extraction to obtain a crude extract of natural borneol.

[0014] Furthermore, the method further comprises: (6) detection: dissolving the crude extract in an organic solvent and determining the content of d-borneol in the crude extract by GC-MS.

[0015] Furthermore, the conditions for stacking and sweating are humidity 40%-90%, temperature 5°C-30°C, and time 1d-8d; the borneol camphor is stacked in a dark place, and the stacked and sweated borneol camphor is turned inside out every 18-24 hours to allow the borneol camphor to sweat fully.

[0016] Furthermore, the conditions for the stacking and sweating are 60% humidity, 15° C., and 6 days;

[0017] Furthermore, in step (3), the borneol camphor is rinsed with water for 1-3 times after sweating, until there is no obvious impurities such as mud and sand visible to the naked eye on the branches and leaves of the borneol camphor; the washed borneol camphor is dried in the shade on a drying platform with a drying thickness of 1-3 cm, and the drying environment is controlled to make the drying temperature 5-15°C, the drying humidity 50-80%, and the drying time 4-8h; the borneol camphor branches and leaves are crushed, and the particle size of the crushed borneol camphor is less than 20 mesh.

[0018] Furthermore, in step (4), the crushed borneol camphor is added to deionized water and ultrasonicated; the ultrasonic conditions are: solid-liquid ratio 1:10-40, ultrasonic time 15-60min, ultrasonic temperature 10-25°C, and the container containing the material is in a closed state during the ultrasonication.

[0019] Furthermore, in step (5), the extraction is carried out at a constant temperature for 1-6 hours.

[0020] Furthermore, the crude natural borneol extract obtained in step (5) is dried over anhydrous Na2SO4, sealed, and stored at 2-6°C.

[0021] Furthermore, in step (6), the crude extract of natural borneol obtained in step (5) is dissolved in ethyl acetate, and the content of natural borneol in the crude extract is determined by GC-MS;

[0022] Furthermore, step (6) includes preparation of test sample and reference sample solutions and GC-MS detection;

[0023] Furthermore, the method for preparing the test sample and reference sample solutions is:

[0024] Test solution: Take an appropriate amount of crude extract, place in a volumetric flask, prepare a 0.1-10 mg / mL concentration solution, filter through a 0.22 μm filter membrane, and store in a refrigerator at 4°C for later use;

[0025] Reference substance solution: Weigh an appropriate amount of borneol reference substance into a 10 mL volumetric flask, add ethyl acetate solution to prepare a reference substance mother solution with a concentration of 1-10 mg / mL, and add ethyl acetate to dilute it 2-120 times.

[0026] Furthermore, the GC-MS detection chromatographic conditions are as follows: the chromatographic column is Agilent J&W HP-5MS (30m×0.25μm, 0.25mm), the carrier gas is high-purity helium, the chromatographic column flow rate is 0.7-1.5mL / min, and the injection volume is 0.5-6μL; the injection port temperature is 220-250°C, and the split ratio is 10-40:1; the column box starting temperature is 50-90°C, maintained for 1-6min, increased to 220-250°C at 8-20°C / min, and maintained for 6-12min; mass spectrometry conditions: injection port temperature is 220-250°C, ion source temperature is 200-280°C; solvent delay is 3-4min, mass spectrometry scanning range is m / z 30-450, and electron energy is 70eV; the GC-MS injection volume is 0.5-6μL, and the content of dextrorotatory borneol in the test solution and the reference solution is determined according to the external standard method.

[0027] On the other hand, the present application provides the application of the above method in preparing natural borneol.

[0028] In another aspect, the present application provides natural borneol prepared using the above method.

[0029] During the sweating process: on the one hand, suitable stacking temperature, stacking humidity and stacking time will cause changes in the activities of various biological enzymes such as oxidoreductase and hydrolase and the dominant bacterial flora, thereby promoting the increase in the content of natural borneol; on the other hand, changes in the above factors will cause changes in the cell wall structure, which will help the extraction of natural borneol.

[0030] During the ultrasonic process: Ultrasonic extraction uses the cavitation and diffusion effects of ultrasound to destroy the cell walls of Camphor and accelerate the dissolution of active ingredients; the mechanical forces such as friction and shear generated during the crushing process destroy the cell walls of Camphor and accelerate the extraction of volatile components.

[0031] The borneol camphor raw materials used in the present application are preferably 1-6 year old fresh borneol camphor branches and leaves.

[0032] The advantages of the present invention are:

[0033] Borneol camphor is mainly produced in Hunan, Jiangxi and other places, and the main extraction time is from October to January of the following year. The present invention comprehensively investigates the temperature and humidity during the period of concentrated extraction of natural borneol in Huaihua City, Hunan Province and Ji'an City, Jiangxi Province, designs process parameters that fit the local environment, and preferably obtains a method for preparing borneol camphor that significantly increases the content of natural borneol by combining ultrasound with steam distillation. The present invention adopts a direct stacking sweating method that fits the local environment, without the need for drying or steaming, and without the need for plastic film covering, to minimize energy loss; the present invention does not use organic solvents to extract natural borneol, and the steam distillation method is combined with ultrasound-assisted extraction, which is green and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Detailed process flow diagram of the method of this application. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention.

[0036] Example 1

[0037] A method for preparing natural borneol for increasing the output of d-borneol, the specific preparation method of which is as follows:

[0038] The fresh borneol camphor branches and leaves are shaken off the surface mud and impurities, and after being piled up and sweated under the conditions of 15°C and relative humidity of 60% for 6 days, they are washed until there is no obvious mud and other impurities visible to the naked eye on the borneol camphor branches and leaves; the washed borneol camphor is dried in the shade on a drying platform with a drying thickness of 1 cm, and the drying environment is controlled to make the drying temperature of 15°C, the drying humidity of 65%, and the drying time of 8 hours. The shade-dried borneol camphor branches and leaves are crushed, deionized water is added according to the solid-liquid ratio of 1:16, and the ultrasonic time is 45 minutes under the conditions of temperature of 25°C, frequency of 40KHz, and power of 360W, and the steam distillation method is heated to reflux for 3 hours, and the yield of the borneol camphor crude extract is 3.29%.

[0039] Example 2

[0040] The fresh borneol camphor branches and leaves are shaken off the surface mud and impurities, and after being piled up and sweated at 15°C and a relative humidity of 60% for 6 days, they are washed until there is no obvious mud and other impurities visible to the naked eye on the borneol camphor branches and leaves; the washed borneol camphor is dried in the shade on a drying platform with a drying thickness of 1 cm, and the drying environment is controlled to make the drying temperature 15°C, the drying humidity 65%, and the drying time 8 hours. The shade-dried borneol camphor branches and leaves are crushed, and deionized water is added according to a solid-liquid ratio of 1:10. The ultrasonic time is 45 minutes under the conditions of temperature 25°C, frequency 40KHz, and power 360W, and the steam distillation method is heated to reflux for 1.5 hours, and the yield of the borneol camphor crude extract is 3.19%.

[0041] Example 3

[0042] The fresh borneol camphor branches and leaves are shaken off the surface mud and impurities, and after being piled up and sweated under the conditions of 15°C and relative humidity of 60% for 6 days, they are washed until there is no obvious mud and other impurities visible to the naked eye on the borneol camphor branches and leaves; the washed borneol camphor is dried in the shade on a drying platform with a drying thickness of 1 cm, and the drying environment is controlled to make the drying temperature 15°C, the drying humidity 65%, and the drying time 8 hours. The shade-dried borneol camphor branches and leaves are crushed, deionized water is added according to the solid-liquid ratio of 1:16, and no ultrasound is used. The steam distillation method is heated to reflux for 1.5 hours, and the yield of the borneol camphor crude extract is 2.13%.

[0043] Example 4

[0044] The fresh borneol camphor branches and leaves are shaken off the surface sand and impurities, and washed after being piled up and sweated under 10 ℃, relative humidity 43% and 2d conditions. The washed borneol camphor is dried in the shade on the airing platform, and the airing thickness is 1cm. The airing environment is controlled to make the airing temperature 15 ℃, the airing humidity 65%, and the airing time 8h. The borneol camphor branches and leaves after being dried in the shade are crushed, and the crushed medicinal materials are added with deionized water according to the solid-liquid ratio of 1:16. The ultrasonic time is 45min under the conditions of temperature 25 ℃, frequency 40KHz, and power 360W, and the steam distillation method is heated to reflux for 2h, and the borneol camphor crude extract is collected. The crude extract is sealed after being dried with anhydrous Na2SO4 and stored at 4 ℃ for standby use. Take 25mg crude extract, place it in a 25mg / mL volumetric flask, dissolve it to the scale with ethyl acetate, and pass through a 0.22μm filter membrane to obtain.

[0045] The prepared test sample was injected into the headspace bottle for sampling and analysis. The specific method of GC-MS is as follows:

[0046] The chromatographic column was Agilent J&W HP-5MS (30m×0.25μm, 0.25mm), the carrier gas was high-purity helium, the column flow rate was 1mL / min, the injection volume was 1μL; the injection port temperature was 250℃, the split ratio was 20:1; the column box initial temperature was 60℃, maintained for 1min, increased to 250℃ at 10℃ / min, maintained for 6min; the injection port temperature was 250℃, the ion source temperature was 230℃; the solvent delay was 3.5min, the mass spectrometry scanning range was m / z 40-400, and the electron energy was 70eV. The content of d-borneol in the crude extract was determined by the external standard method to be 0.47mg·mL-1.

[0047] Example 5

[0048] The fresh borneol camphor branches and leaves were shaken off the surface sand and impurities, and washed after being piled up and sweated under the conditions of 10°C, 82% relative humidity and 6d. The washed borneol camphor was dried in the shade on the airing platform, and the airing thickness was 1cm. The airing environment was controlled to make the airing temperature 15°C, the airing humidity 65%, and the airing time 8h. The borneol camphor branches and leaves after being dried in the shade were crushed, and the crushed medicinal materials were added with deionized water according to a solid-liquid ratio of 1:16. The ultrasonic time was 45min under the conditions of temperature 25°C, frequency 40KHz, and power 360W, and the steam distillation method was heated to reflux for 2h to collect the borneol camphor crude extract. The crude extract was sealed after drying with anhydrous Na2SO4 and stored at 4°C for standby use.

[0049] Take 25 mg of the crude extract, place it in a 25 mg / mL volumetric flask, dissolve it to the scale with ethyl acetate, and filter it through a 0.22 μm filter membrane to obtain the product.

[0050] The prepared test sample was injected into the headspace bottle for sampling and analysis. The specific method of GC-MS is as follows:

[0051] The chromatographic column was Agilent J&W HP-5MS (30m×0.25μm, 0.25mm), the carrier gas was high-purity helium, the column flow rate was 1mL / min, the injection volume was 1μL; the injection port temperature was 250℃, the split ratio was 20:1; the column box initial temperature was 60℃, maintained for 1min, increased to 250℃ at 10℃ / min, maintained for 6min; the injection port temperature was 250℃, the ion source temperature was 230℃; the solvent delay was 3.5min, the mass spectrometry scanning range was m / z 40-400, and the electron energy was 70eV. The content of d-borneol in the crude extract was determined by the external standard method to be 0.58mg·mL-1.

[0052] Example 6

[0053] The fresh borneol camphor branches and leaves are shaken off the surface silt and impurities, and washed after being piled up and sweated under the conditions of 15°C, 60% relative humidity and 6d. The washed borneol camphor is dried in the shade on the airing platform, and the airing thickness is 1cm. The airing environment is controlled to make the airing temperature 15°C, the airing humidity 65%, and the airing time 8h. The borneol camphor branches and leaves after being dried in the shade are crushed, and the crushed medicinal materials are added with deionized water according to a solid-liquid ratio of 1:16. The ultrasonic time is 45min under the conditions of temperature 25°C, frequency 40KHz, and power 360W, and the steam distillation method is heated to reflux for 2h to collect the borneol camphor crude extract. The crude extract is sealed after drying with anhydrous Na2SO4 and stored at 4°C for standby use.

[0054] Take 25 mg of the crude extract, place it in a 25 mg / mL volumetric flask, dissolve it to the scale with ethyl acetate, and filter it through a 0.22 μm filter membrane to obtain the product.

[0055] The prepared test sample was injected into the headspace bottle for sampling and analysis. The specific method of GC-MS is as follows:

[0056] The chromatographic column was Agilent J&W HP-5MS (30m×0.25μm, 0.25mm), the carrier gas was high-purity helium, the column flow rate was 1mL / min, the injection volume was 1μL; the injection port temperature was 250℃, the split ratio was 20:1; the column box initial temperature was 60℃, maintained for 1min, increased to 250℃ at 10℃ / min, maintained for 6min; the injection port temperature was 250℃, the ion source temperature was 230℃; the solvent delay was 3.5min, the mass spectrometry scanning range was m / z 40-400, and the electron energy was 70eV. The content of d-borneol in the crude extract was determined by the external standard method to be 0.61mg·mL-1.

[0057] Example 7

[0058] The fresh borneol camphor branches and leaves are shaken off the surface silt and impurities, and washed after being piled up and sweated under the conditions of 20°C, 82% relative humidity and 4d. The washed borneol camphor is dried in the shade on the airing platform, and the airing thickness is 1cm. The airing environment is controlled to make the airing temperature 15°C, the airing humidity 65%, and the airing time 8h. The borneol camphor branches and leaves after being dried in the shade are crushed, and the crushed medicinal materials are added with deionized water according to a solid-liquid ratio of 1:16. The ultrasonic time is 45min under the conditions of temperature 25°C, frequency 40KHz, and power 360W, and the steam distillation method is heated to reflux for 2h to collect the borneol camphor crude extract. The crude extract is sealed after drying with anhydrous Na2SO4 and stored at 4°C for standby use.

[0059] Take 25 mg of the crude extract, place it in a 25 mg / mL volumetric flask, dissolve it to the scale with ethyl acetate, and filter it through a 0.22 μm filter membrane to obtain the product.

[0060] The prepared test sample was injected into the headspace bottle for sampling and analysis. The specific method of GC-MS is as follows:

[0061] The chromatographic column was Agilent J&W HP-5MS (30m×0.25μm, 0.25mm), the carrier gas was high-purity helium, the column flow rate was 1mL / min, the injection volume was 1μL; the injection port temperature was 250℃, the split ratio was 20:1; the column box initial temperature was 60℃, maintained for 1min, increased to 250℃ at 10℃ / min, and maintained for 6min; the injection port temperature was 250℃, the ion source temperature was 230℃; the solvent delay was 3.5min, the mass spectrometry scanning range was m / z 40-400, and the electron energy was 70eV. The content of d-borneol in the crude extract was determined by the external standard method to be 0.54mg·mL-1.

[0062] Example 8

[0063] The fresh borneol camphor branches and leaves were shaken off the surface sand and impurities, and the washed borneol camphor was dried in the shade on the airing platform, the airing thickness was 1cm, the airing environment was controlled, the airing temperature was 15°C, the airing humidity was 65%, and the airing time was 8h. The borneol camphor branches and leaves after being dried in the shade were crushed as a non-sweating control group. The crushed medicinal material was added with deionized water according to a solid-liquid ratio of 1:16, and the ultrasonic time was 45min under the conditions of temperature 25°C, frequency 40KHz, and power 360W, and the steam distillation method was heated to reflux for 2h to collect the borneol camphor crude extract. The crude extract was sealed after drying with anhydrous Na2SO4 and stored at 4°C for standby use.

[0064] Take 25 mg of the crude extract, place it in a 25 mg / mL volumetric flask, dissolve it to the scale with ethyl acetate, and filter it through a 0.22 μm filter membrane to obtain the product.

[0065] The prepared test sample was injected into the headspace bottle for sampling and analysis. The specific method of GC-MS is as follows:

[0066] The chromatographic column was Agilent J&W HP-5MS (30m×0.25μm, 0.25mm), the carrier gas was high-purity helium, the column flow rate was 1mL / min, the injection volume was 1μL; the injection port temperature was 250℃, the split ratio was 20:1; the column box initial temperature was 60℃, maintained for 1min, increased to 250℃ at 10℃ / min, maintained for 6min; the injection port temperature was 250℃, the ion source temperature was 230℃; the solvent delay was 3.5min, the mass spectrometry scanning range was m / z 40-400, and the electron energy was 70eV. The content of d-borneol in the crude extract was determined by the external standard method to be 0.48mg·mL-1.

[0067] Results of GC-MS Methodology Investigation in Examples 4-8

[0068] Standard curve drawing: Accurately pipette each gradient concentration solution under item 2.4 and inject 1 μL. Use concentration (mg / mL) as the horizontal coordinate (x) and peak area as the vertical coordinate (y) to draw the standard curve of d-borneol and obtain the regression equation and its linear range. The standard curve of d-borneol is Y=1.4*106X-8.8*104 (R2=0.9992), indicating that d-borneol has a good linear range of 0.055-2.00 mg / mL;

[0069] Precision experiment: Accurately pipette 1 μL of the mother solution of the reference substance and inject it six times in a row. Determine the peak area of ​​d-borneol and camphor and calculate the RSD value. The measured d-borneol RSD = 1.53 (%), indicating that the instrument has good precision;

[0070] Stability test: Take the crude extract test solution, inject 1 μL at 2, 4, 6, 8, 10, and 12 hours, and measure the peak area of ​​d-borneol. The measured d-borneol RSD is 2.07 (%), indicating that the test solution has good stability within 12 hours;

[0071] Repeatability experiment: Take 6 portions of crude extract of S2 and prepare them into 6 portions of test solution respectively. Inject 1 μL, determine the peak area of ​​d-borneol, and measure the RSD of d-borneol = 1.98 (%), indicating that the method has good repeatability. Sample addition recovery experiment: Take 9 portions of crude extracts of the same batch with known content, each 50 mg, and prepare them into 6 portions of test solution respectively, and add reference substances according to 80%, 100%, and 120% of the d-borneol content. Inject 1 μL, determine the d-borneol content, and calculate the recovery rate and RSD value. The average recovery rate of d-borneol was measured to be 100.4%, RSD = 2.19 (%), indicating that the recovery rate of this method is good. The results are shown in Table 1:

[0072] Table 1 Dextrorotatory Borneol sample recovery experimental results

[0073]

[0074] The growth rate of d-borneol in Examples 4-8 is shown in Table 2:

[0075] Table 2 Preferred borneol growth rate (Examples 4-7 are "sweating" groups, Example 8 is "non-sweating" group)

[0076]

[0077] The method provided by the present invention significantly increases the content of natural borneol in borneol camphor. Compared with fresh sample shade drying, stacking and sweating can significantly increase the output of natural borneol, alleviate the current situation of shortage of natural borneol resources to a certain extent, and reduce the utilization rate of synthetic borneol in medicine and daily chemical products. The preparation method provided by the present invention is green and environmentally friendly, and increases the output of right-handed borneol by optimizing sweating, airing, ultrasound and steam distillation extraction conditions, without the need to use chemical reagents to induce borneol camphor.

[0078] The above content is only a further description of the present invention in combination with specific embodiments. It should be noted that for ordinary technicians in this technical field, they are not limited to the specific implementation content of the present invention. Without departing from the concept of the present invention, several deductions or substitutions can be made, and these deductions or substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing natural borneol for increasing the yield of d-borneol, characterized in that: The method for preparing natural borneol comprises the following steps: (1) selecting medicinal materials: removing impurities such as mud, sand, and insect eggs from fresh camphor; (2) stacking and sweating: stacking and sweating the cleaned camphor for 6 days at a humidity of 60% and a temperature of 15°C; (3) raw material pretreatment: washing the camphor after the stacking and sweating with water, drying in the shade, and then crushing; (4) ultrasonication: adding the crushed camphor to a solvent for ultrasonication; (5) extraction: transferring the ultrasonicated camphor to an extraction device for steam distillation extraction to obtain a crude natural borneol extract.

2. The method for preparing natural borneol according to claim 1, wherein the method further comprises: (6) Detection: The crude extract was dissolved in an organic solvent and the content of d-borneol in the crude extract was determined by GC-MS.

3. The method for preparing natural borneol according to claim 1, wherein in step (3), the borneol camphor leaves after sweating are rinsed with water for 1-3 times until there is no obvious impurities such as mud and sand visible to the naked eye on the branches and leaves of the borneol camphor; the washed borneol camphor is dried in the shade on a spreading platform with a spreading thickness of 1-3 cm, and the spreading environment is controlled to make the spreading temperature 5-15°C, the spreading humidity 50-80%, and the spreading time 4-8h; the borneol camphor leaves after drying in the shade are crushed, and the particle size of the crushed borneol camphor is less than 20 mesh.

4. The method for preparing natural borneol according to claim 1, wherein in step (4), the crushed borneol camphor is added to deionized water and ultrasonicated; the ultrasonic conditions are: solid-liquid ratio 1:10-40, ultrasonic time 15-60min, ultrasonic temperature 10-25°C, and the container containing the material is in a closed state during the ultrasonication.

5. The method for preparing natural borneol according to claim 1, wherein in step (5), the constant temperature extraction is performed for 1-6 hours; the obtained crude natural borneol extract is dried over anhydrous Na2SO4, sealed, and stored at 2-6°C.

6. Use of the method for preparing natural borneol according to any one of claims 1 to 5 in preparing natural borneol.

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