Extraction method and application of elaeagnus angustifolia polyphenol

Abstract

The invention relates to the technical field of polyphenol extraction, and particularly discloses an elaeagnus angustifolia polyphenol extraction method and application thereof.According to the extraction method, through an ultrasonic extraction mode, the extraction temperature is determined to be 40 DEG C, the ethanol concentration is 80%, the ultrasonic extraction frequency is 4 times, the ultrasonic extraction time is 30 min, and the ethanol solid-liquid ratio is 1: 10 (g: mL). The volume fraction of ethanol, the material-liquid ratio, the extraction time, the extraction temperature and the extraction times during extraction are regulated and controlled, so that the extraction amount of the packaged polyphenol is optimal, a traditional extraction process is optimized, and waste of elaeagnus angustifolia resources is effectively avoided.

Description

Technical Field

[0001] This invention belongs to the field of polyphenol extraction technology, specifically relating to a method for extracting polyphenols from jujube and its application. Background Technology

[0002] The sand date (Elaeagnus sangustifolia L.) is a perennial deciduous tree belonging to the genus Elaeagnus in the family Elaeagnaceae. Xinjiang sand date is a fruit endemic to the Xinjiang Uygur Autonomous Region of China, also known as the "Oriental Ruby." The flesh of the sand date is rich in various nutrients, mainly including sugars, fats, proteins, and minerals. The nutritional composition of the sand date varies depending on its source and variety, but the main components of its flesh are carbohydrates and proteins. In addition to abundant fructose and glucose, the carbohydrates also include polysaccharides and fiber. Chen Kui et al. found that the fructose content is as high as over 20% of carbohydrates, protein is about 7%~10%, organic acids 3%, pectin 1.2%, and also contains small amounts of tannins and mucilage.

[0003] Polyphenols are named for their multiple phenolic structural units. They are phenolic hydroxyl compounds produced by plant secondary metabolism, and are diverse in type, complex in structure, and widely sourced.

[0004] In recent years, some new extraction methods based on solvent extraction have emerged, such as ultrasonic extraction, microwave extraction, and supercritical carbon dioxide extraction. Among them, ultrasonic extraction is widely used in industrial and scientific research due to its advantages such as high extraction rate of active ingredients from traditional Chinese medicine and short extraction time.

[0005] Currently, in practical applications of ultrasonic extraction, staff cannot accurately determine the specific ethanol volume fraction, material-to-liquid ratio, extraction time, extraction temperature, and number of extractions, which can lead to a certain waste of jujube resources during the extraction process. Summary of the Invention

[0006] The purpose of this invention is to provide a method for extracting polyphenols from jujube and its application, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for extracting polyphenols from jujube trees includes the following steps:

[0009] Includes the following steps:

[0010] S1. Raw material selection:

[0011] Select large-fruited jujubes from Xinjiang, dry them in an oven at 45℃, crush them, remove the pits, and grind the pulp to obtain large-fruited jujube pulp powder, which should be sealed and stored for later use.

[0012] S2. Raw material mixing:

[0013] Prepare an ethanol solution for extraction with an ethanol volume fraction of 80%. Then, mix the sealed and stored large-fruited jujube pulp powder with the 80% ethanol solution at a material-to-liquid ratio of 1:10 (g:mL). S3. Raw material extraction:

[0014] After mixing, the mixture was placed in an ultrasonic extraction device. The extraction temperature was set to 40℃ and the ultrasonic extraction time was 30 min. The mixture was extracted 4 times. After each ultrasonic extraction, it was allowed to stand for 10 min. After the first extraction, the mixture was separated into solid and liquid components. The extract was collected and the residue was retained. Then, the residue was extracted a second time according to the same material-liquid ratio, ethanol volume fraction, extraction temperature and extraction time. After the extraction, solid and liquid were separated again and the second extract was collected.

[0015] Following the same method, the residue was extracted a third and fourth time, and the third and fourth extracts were collected respectively. After all four extraction operations were completed, the collected extracts were combined to complete the preparation process of the jujube polyphenol of the present invention. After each extraction and standing, the supernatant was collected by using a Buchner funnel and a vacuum filtration device.

[0016] Preferred applications of jujube polyphenols include the preparation of pharmaceuticals that enhance immunity, as well as those that have diuretic, antipyretic, cholesterol-lowering, colitis-protective, lipid-lowering, and wound-healing properties.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention optimizes the traditional extraction process and effectively avoids the waste of jujube resources by controlling the ethanol volume fraction, material-liquid ratio, extraction time, extraction temperature, and number of extractions during the ultrasonic extraction of jujube polyphenols. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the effect of the material-to-liquid ratio on the concentration of the total polyphenol extract according to the present invention.

[0020] Figure 2 This is a schematic diagram illustrating the effect of the ethanol solution concentration on the total polyphenol extract concentration according to the present invention.

[0021] Figure 3 This is a schematic diagram illustrating the effect of ultrasonic extraction time on the concentration of the total polyphenol extraction solution according to the present invention;

[0022] Figure 4 This is a schematic diagram illustrating the effect of the number of ultrasonic extractions on the concentration of the total polyphenol extract according to the present invention.

[0023] Figure 5 This is a schematic diagram of the standard curve of polyphenols using gallic acid as a standard in this invention;

[0024] Figure 6 This is a schematic diagram illustrating the effect of extraction time and number of extractions of Xinjiang large-fruited jujube pulp on polyphenol concentration according to the present invention.

[0025] Figure 7 Contour plot showing the effect of extraction time and number of extractions of Xinjiang large-fruited jujube pulp on polyphenol concentration according to the present invention;

[0026] Figure 8 This figure shows the effect of ultrasonic extraction time and ethanol concentration on the polyphenol concentration in the extract of the Xinjiang large-fruited jujube pulp according to the present invention.

[0027] Figure 9 Contour plot showing the effect of ultrasonic extraction time and ethanol concentration on polyphenol concentration in the extract of the Xinjiang large-fruited jujube pulp according to the present invention.

[0028] Figure 10 This figure shows the effect of the number of ultrasonic extractions and ethanol concentration on the polyphenol concentration in the extract of the Xinjiang large-fruited jujube pulp according to the present invention.

[0029] Figure 11 This is a contour plot showing the effect of the number of ultrasonic extractions and ethanol concentration on the polyphenol concentration in the extract of the Xinjiang large-fruited jujube pulp according to the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1:

[0032] Please see Figures 1 to 11 As shown, a method for extracting polyphenols from jujube trees specifically includes the following steps:

[0033] Select large-fruited jujubes from Xinjiang, dry them in an oven at 45℃, crush them, remove the pits, and pulverize the pulp to obtain large-fruited jujube pulp powder. Store the powder in a sealed container for later use. Prepare an ethanol solution for extraction with an ethanol volume fraction of 80%. Then, mix the sealed large-fruited jujube pulp powder with the 80% ethanol solution at a material-to-liquid ratio of 1:10 (g:mL). After mixing, place the mixture in an ultrasonic extraction device, set the extraction temperature to 40℃, and the ultrasonic extraction time to 30 minutes. Extract for a total of 4 times. After each ultrasonic extraction, let it stand for 10 minutes. After the first extraction, perform solid-liquid separation on the mixture, collect the extract, and retain the residue. Then, perform a second extraction on the residue using the same material-to-liquid ratio, ethanol volume fraction, extraction temperature, and extraction time. After the extraction, perform solid-liquid separation again and collect the second extract.

[0034] Following the same method, the residue was extracted a third and fourth time, and the third and fourth extracts were collected respectively. After all four extraction operations were completed, the collected extracts were combined to complete the preparation process of the jujube polyphenol of the present invention. After each extraction and standing, the supernatant was collected by using a Buchner funnel and a vacuum filtration device.

[0035] Experimental verification:

[0036] Select large-fruited jujubes from Xinjiang, dry them in an oven at 45℃, crush them, remove the pits, and grind the pulp to obtain large-fruited jujube pulp powder, which should be sealed and stored for later use.

[0037] The total polyphenol extraction rate was used as the evaluation index to determine the effects of four factors on the total polyphenol extraction rate: different material-liquid ratio, solvent concentration, ultrasonic time, and extraction times.

[0038] Effect of solid-liquid ratio on total polyphenol extraction rate

[0039] Accurately weigh 5.0 g of finely powdered jujube pulp into a 150 mL Erlenmeyer flask. At a constant temperature of 40℃, set the ethanol concentration for extraction to 75%, and perform ultrasonic extraction at liquid-to-solid ratios of 5:1, 10:1, 15:1, 20:1, 25:1, and 30:1, respectively. Perform ultrasonic extraction twice for a total of 20 min. After each ultrasonic extraction, allow the mixture to stand for 10 min, then filter the supernatant using a Buchner funnel and vacuum filtration device. Transfer the supernatant to a 250 mL volumetric flask, combine the multiple polyphenol extracts, and dilute to volume with 75% ethanol solution. Transfer the diluted solution to an EP tube for later use and analysis.

[0040] Effect of solvent concentration on total polyphenol extraction rate

[0041] Accurately weigh 5.0 g of finely powdered jujube pulp into a 150 mL Erlenmeyer flask. At a constant temperature of 40℃, set the extraction solid-liquid ratio to 1:10, and add ethanol of different concentrations (95%, 85%, 75%, 65%, 55%, and 45%) for ultrasonic extraction twice, for a total of 20 min. After each ultrasonic extraction, allow the mixture to stand for 10 min, then filter the supernatant using a Buchner funnel and vacuum filtration device. Transfer the supernatant to a 250 mL volumetric flask, combine the multiple polyphenol extracts, and dilute to volume with 75% ethanol solution. Transfer the solution to an EP tube for later use and analysis.

[0042] Effect of ultrasonic extraction time on total polyphenol extraction rate

[0043] Accurately weigh 5.0 g of finely powdered Elaeagnus angustifolia pulp into a 150 mL Erlenmeyer flask. Extract with 75% ethanol solution at a constant temperature of 40℃ and a solid-liquid ratio of 1:10. The extraction was performed twice, with total extraction times of 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min. After each ultrasonic extraction, allow the mixture to stand for 10 min. Using a Buchner funnel and vacuum filtration device, filter the supernatant and transfer it to a 250 mL volumetric flask. Combine the multiple polyphenol extracts, dilute to volume with 75% ethanol solution, and transfer to an EP tube for later analysis.

[0044] Effect of extraction times on total polyphenol extraction rate

[0045] Accurately weigh 5.0 g of finely powdered jujube pulp into a 150 mL Erlenmeyer flask. Under constant temperature of 40℃ and a solid-liquid ratio of 1:10, add 75% ethanol solution and perform ultrasonic extraction for 20 min each time, setting the extraction frequency to 1, 2, 3, 4, and 5 times. After each ultrasonic extraction, allow to stand for 10 min, then filter the supernatant using a Buchner funnel and vacuum filtration device. Transfer the supernatant to a 250 mL volumetric flask, combine the multiple polyphenol extracts, and dilute to volume with 75% ethanol solution. Transfer the solution to an EP tube for later use and analysis.

[0046] Plotting the standard curve for polyphenols;

[0047] Dissolve 50 mg of gallic acid, dried to constant weight, in distilled water, dilute to volume in a 25 mL volumetric flask, and store in a brown bottle to obtain the standard solution (2 mg / mL). Prepare gallic acid solutions with concentrations of 0.02 mg / mL, 0.04 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.12 mg / mL, 0.14 mg / mL, 0.18 mg / mL, and 0.2 mg / mL based on the standard solution.

[0048] Accurately pipette 10 μL of gallic acid solution into a 96-well cell culture plate, add 30 μL of Folin-Ciocalteu reagent, shake to mix, and react for 6 min. Add 40 μL of 7.5% Na₂CO₃ solution, mix thoroughly, and then add 170 μL of distilled water. Incubate at 37°C in the dark for 30 min, and measure the absorbance at 765 nm. Construct a standard curve with concentration on the x-axis and absorbance on the y-axis, and perform three parallel experiments.

[0049] ELISA reader for measuring total polyphenol content

[0050] 10 μL of each of the jujube extract solutions prepared using the single-factor method was injected into the wells of an ELISA plate. 30 μL of Folin-Ciocalteu reagent was added to each well, and the mixture was shaken and reacted for 6 min. Then, 40 μL of 7.5% Na₂CO₃ solution was added, and the mixture was thoroughly mixed. Finally, 170 μL of distilled water was added. The plate was incubated at 37°C in the dark for 30 min, and the absorbance was measured at 765 nm. The experiment was repeated three times, and the polyphenol extract content and extraction rate were calculated using the average of the three results.

[0051] Response surface methodology Box-Behnken design experiment optimization

[0052] Accurately weigh 3.0g of finely powdered jujube pulp into a 150mL Erlenmeyer flask. Under constant temperature of 40℃ and a liquid-to-solid ratio of 15:1, the experimental levels of the other three independent variables were coded as -1, 0, and 1, respectively (see Table 3). A total of 15 experimental points were designed for the experiment. After each ultrasonic extraction, the mixture was allowed to stand for 10min. The supernatant was filtered using a Buchner funnel and a vacuum filtration device and transferred to a 250mL volumetric flask. The polyphenol extracts were combined and diluted to volume with 75% ethanol solution. The solution was then transferred to an EP tube for later use and analysis.

[0053] 10 μL of the jujube extract solution from the above response surface methodology optimization experiment was injected into each well of an ELISA plate. 30 μL of Folin-Ciocalteu reagent was added, and the mixture was shaken and reacted for 6 min. Then, 40 μL of 7.5% Na₂CO₃ solution was added, and the mixture was thoroughly mixed. Finally, 170 μL of distilled water was added. The plate was incubated at 37℃ in the dark for 30 min, and the absorbance was measured at 765 nm. The experiment was repeated three times, and the polyphenol extract content and extraction rate were calculated using the average of the three results.

[0054] Table 3. Factors and levels in the Box-Benhnken experimental design

[0055]

[0056] Table 4. Response surface methodology for the concentration of polyphenol extract from Xinjiang large-fruited jujube fruit.

[0057]

[0058] Table 4 (Continued) - Response Surface Methodology for Polyphenol Extract Concentration of Xinjiang Large-Fruited Jujube Fruit

[0059]

[0060] Single-factor extraction analysis of polyphenols from Xinjiang large-fruited jujube:

[0061] Effect of solid-liquid ratio on the concentration of total polyphenol extract

[0062] Depend on Figure 1 It can be seen that as the solid-liquid ratio increases, the content increases from 0.67 mg / g to 1.79 mg / g. When the solid-liquid ratio is greater than 1:10, the concentration of the extract increases slowly to 1.97 mg / g with further increases in the solid-liquid ratio, and then slowly decreases. This may be because when the solid-liquid ratio is 1:10, the polyphenolic components in the jujube have been completely extracted, and further increases in the amount of extraction solvent will not increase the concentration accordingly. Therefore, a solid-liquid ratio of around 1:10 is more reasonable.

[0063] The effect of ethanol solution concentration on the concentration of total polyphenol extract;

[0064] like Figure 2 As shown, when ethanol solution is used as the extraction solvent, the polyphenol content increases from 1.35 mg / g to 1.76 mg / g, and the volume fraction of ethanol solution is 75%.

[0065] When ethanol is used as the extraction solvent, the maximum extraction volume reaches 75%. Therefore, polyphenols are extracted more efficiently in an ethanol solution with a concentration of approximately 75%.

[0066] Effect of ultrasonic extraction time on the concentration of total polyphenol extract

[0067] Depend on Figure 3 It was observed that with increasing ultrasonic extraction time, the concentration of polyphenols in the extract of *Juglans regia* (a type of jujube) increased from 1.67 mg / g to 1.85 mg / g. After extraction exceeding 30 minutes, the concentration decreased to 1.81 mg / g, then rose to 1.83 mg / g. This may be because polyphenolic compounds are easily oxidized and further polymerized in air, leading to a decrease in content. Therefore, we placed the extracted sample in a refrigerator immediately to prevent oxidation at room temperature, which would affect the extraction time. Furthermore, as ultrasonic extraction time increases, the ultrasonic instrument temperature continues to rise, potentially accelerating the degradation of phenolic compounds. Simultaneously, the energy provided by ultrasound may also degrade unstable phenolic compounds, resulting in a decrease in content. Therefore, extraction times exceeding 30 minutes are not advisable. Considering the experimental results and other factors, it can be preliminarily inferred that the ideal extraction time for the total polyphenol extract is approximately 30 minutes.

[0068] The effect of the number of ultrasonic extractions on the concentration of total polyphenol extract;

[0069] Depend on Figure 4 It can be seen that with the increase of ultrasonic extraction times, the concentration of polyphenols in the extract of Xinjiang large-fruited jujube slowly increased from 0.18 mg / g to 0.99 mg / g. When the number of extractions exceeded 3 times, the concentration of the extract increased more rapidly. Therefore, the ideal number of extractions for the total polyphenol extract is around 5 times.

[0070] Standard curve of polyphenol extract

[0071] The design employed gallic acid solution to plot polyphenol standard curves. Three parallel experiments were conducted with gallic acid solutions of 0.02 mg / mL, 0.04 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.12 mg / mL, 0.14 mg / mL, 0.18 mg / mL, and 0.2 mg / mL. The resulting standard curves for polyphenol extracts in the 0.02 mg / mL–0.2 mg / mL range showed a good fit (R² = 0.9900), indicating a good fit to the concentration changes of multiple extracts within this range. The equation is y = 2.2658x + 0.0134, which allows for the accurate calculation of extract concentrations in both the single-factor group and the response surface methodology optimization group.

[0072] Response surface optimization

[0073] The following table was created based on the response surface methodology (RSM) optimization experiment. A 3D image of the RSM optimization experiment was then plotted using the data in the table, and the image was analyzed.

[0074] Table 5. Analysis of Variance Table

[0075]

[0076] A p-value < 0.05 indicates that the model terms are significant. In this case, A, C, A2, B2, and C2 are important model terms.

[0077] Table 6. Response surface methodology results for the concentration of polyphenol extract from Xinjiang Jujube fruit.

[0078]

[0079]

[0080] The effects of ultrasonic extraction time and number of ultrasonic extractions;

[0081] from Figure 7 The contour map shown reveals a clear interaction between ultrasonic extraction time and the number of ultrasonic extraction cycles in optimizing the polyphenol extraction process of Xinjiang large-fruited jujube. According to... Figure 6 The response surface shown indicates that the polyphenol content in the crude extract of jujube pulp reaches its maximum value within a specific range of ultrasonic extraction time and number of extractions. This maximum value occurs within the range of ultrasonic extraction time (24.69-36.02 min) and number of extractions (3.99-4.56).

[0082] according to Figure 9 The contour map shown clearly demonstrates a significant interaction between ultrasonic extraction time and ethanol concentration in optimizing the polyphenol extraction process of Xinjiang large-fruited jujube. Therefore, predicting the polyphenol content in the crude extract of jujube pulp lays the foundation for further research on its bioactivity. Figure 8 The response surface shown indicates that the polyphenol content extracted from the crude extract of *Elaeagnus angustifolia* pulp reaches its maximum value under specific ultrasonic extraction times and ethanol concentrations. This maximum value occurs within a certain range: ultrasonic extraction time 24.29-36.42 min, and ethanol concentration 78.60-84.46%. Furthermore, based on the density of the contour plots showing the effects of ultrasonic extraction time and ethanol concentration on polyphenol concentration in the extract, it can be inferred that for *Elaeagnus angustifolia* pulp, ultrasonic extraction time and ethanol concentration have a highly significant impact on the polyphenol extraction rate.

[0083] The effects of ultrasonic extraction times and ethanol concentration;

[0084] from Figure 11 The contour plot shown reveals a clear interaction between the number of ultrasonic extractions and the ethanol concentration. According to... Figure 10 The response surface shown leads to the conclusion that, under certain extraction times and material amounts, the polyphenol content in the extract obtained from the crude extract of Elaeagnus angustifolia pulp exhibits a maximum value. This maximum value occurs within the range of 3.51-4.66 ultrasonic extraction cycles and 78.94-84.46% ethanol concentration. Furthermore, based on the density of the contour plots showing the effects of ultrasonic extraction cycles and ethanol concentration on the polyphenol concentration in the extract, it is evident that the number of ultrasonic extraction cycles and ethanol concentration have a significant impact on the polyphenol content in the extract.

[0085] In summary, this invention investigated four factors (ultrasonic extraction time, number of ultrasonic extractions, ethanol concentration of the extract, and solid-liquid ratio) affecting the concentration of polyphenols in the extract of Xinjiang large-fruited jujube through single-factor experimental design. The optimal conditions for each factor were preliminarily obtained, and the results are as follows: when the ultrasonic extraction time was 30 min, the total polyphenol content was 1.85 mg / g; when the number of ultrasonic extractions was 5, the total polyphenol content was 4.94 mg / g; when the ethanol concentration was 75%, the total polyphenol concentration was 1.76 mg / g; and when the liquid-to-solid ratio was 10:1, the total polyphenol content was 1.91 mg / g.

[0086] Gallic acid was used as a standard in this experiment to plot a polyphenol standard curve for gallic acid solution. Three parallel experiments were conducted with gallic acid solutions of 0.02 mg / mL, 0.04 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.12 mg / mL, 0.14 mg / mL, 0.18 mg / mL, and 0.2 mg / mL to obtain the polyphenol extract standard curve in the range of 0.02 mg / mL to 0.2 mg / mL. The goodness of fit R² = 0.9900 indicates that it can fit the concentration changes of multiple extracts in the range of 0.02 mg / mL to 0.2 mg / mL well.

[0087] Orthogonal experiments using response surface methodology (RSM) were conducted on the single-factor results to find the optimal process conditions. The results of the orthogonal experiments using RSM can intuitively reflect the degree of influence of the interaction on the response value through the steepness of the surface and the density of the contour lines. When the contour lines approach an ellipse, it indicates that the interaction between the two factors is stronger; while dense contour lines mean that the influence is more significant.

[0088] Therefore, a design-export method was used, and three parallel experiments were conducted on the designed scheme. After further processing the experimental results, the optimal extraction conditions were obtained as follows: ethanol volume fraction of 80%, solid-liquid ratio of 1:10 (g:mL), extraction time of 30 min, extraction temperature of 40℃, and extraction times of 4. Under these optimal conditions, the polyphenol content extracted from the pulp of Xinjiang large-fruited jujube was 3.00 mg / g. The total polyphenol concentration obtained under the above optimal conditions is consistent with the literature reports, indicating that the experimental method is reasonable and the operation is appropriate.

[0089] The experimental results show that Elaeagnus angustifolia is rich in polyphenolic compounds, which have a variety of pharmacological activities, including antioxidant, antibacterial, and anti-inflammatory effects. Due to its rich polyphenolic content, extraction under optimal process conditions yields a high-concentration Elaeagnus angustifolia polyphenol extract, which can be further investigated to provide more theoretical basis for its development and utilization.

[0090] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for extracting polyphenols from Elaeagnus angustifolia L., characterized by, The method comprises the following steps: S1. Raw material selection: Xinjiang big fruit Elaeagnus angustifolia L. is selected, dried in an oven at 45℃, broken and cored, and the fruit pulp is crushed to obtain big fruit Elaeagnus angustifolia L. pulp powder, which is stored in a sealed state for later use; S2. Raw material mixing: An ethanol solution for extraction is prepared according to an ethanol volume fraction of 80%, and then the big fruit Elaeagnus angustifolia L. pulp powder stored in a sealed state is mixed with the 80% ethanol solution according to a solid-liquid ratio of 1:10 (g:mL); S3. Raw material extraction: After the mixing is completed, the mixed system is placed in an ultrasonic extraction device, the extraction temperature is set to 40℃, the ultrasonic extraction time is set to 30 min, and the extraction is performed for a total of 4 times. After each ultrasonic extraction is completed, the system is allowed to stand for 10 min. After the first extraction is completed, the mixed system is subjected to solid-liquid separation, the extraction liquid is collected, and the residue is retained. Subsequently, the residue is subjected to a second extraction according to the same solid-liquid ratio, ethanol volume fraction, extraction temperature, and extraction time. After the second extraction is completed, the system is again subjected to solid-liquid separation, and the second extraction liquid is collected. In the same way, the residue is subjected to a third and a fourth extraction, and the third and fourth extraction liquids are collected. After the four extraction operations are completed, the four extraction liquids collected are combined, and the preparation process of the Elaeagnus angustifolia L. polyphenol is completed. After each extraction is allowed to stand, a Buchner funnel and a suction filtration device are used to perform suction filtration, and the supernatant is collected.

2. The application of the Elaeagnus angustifolia L. polyphenol extracted by the Elaeagnus angustifolia L. polyphenol extraction method according to claim 1 in the preparation of medicines for enhancing immunity, diuresis, antipyretic, lowering cholesterol, protecting against colitis, reducing blood lipids, and promoting wound healing.

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