A willowleaf vegetable extract, its extraction method and application

Abstract

This invention discloses a willowherb extract, its extraction method, and its applications, belonging to the field of plant extraction technology. By adjusting the extraction process, this application achieves thorough extraction of willowherb, ensuring the complete extraction of its active ingredients and effectively guaranteeing the extract yield. The extract obtained using the extraction method described in this application contains various whitening active ingredients, which can effectively alleviate oxidative stress and inflammatory responses, thereby reducing pigment deposition and achieving a whitening effect.

Description

Technical Field

[0001] This invention belongs to the field of plant extraction technology, specifically relating to a willowherb extract, its extraction method, and its application. Background Technology

[0002] Willowleaf herb, also known as water lily, water orchid, and vegetable spirit, is the dried whole herb of the willow leaf plant (Salix viminalis), belonging to the genus Salix viminalis in the family Onagraceae. Willowleaf herb is a perennial herb with over 200 species worldwide. It is mainly found in sandy riverbeds, sunny and damp areas along ditches and lakes, and in thickets at altitudes of 1000–4000 meters, and is widely distributed in Sichuan, Guizhou, Yunnan, Jilin, Liaoning, Jiangsu, Zhejiang, and other regions.

[0003] Willowleaf lettuce has been widely used in traditional Chinese medicine, for conditions such as prostate, urinary tract, bladder, gastrointestinal diseases or inflammation, and epilepsy. The flowers, roots, and the whole plant (including roots) can all be used medicinally. The whole plant, bitter, bland, and cold in nature, has the effects of clearing heat and detoxifying, promoting diuresis and stopping diarrhea, aiding digestion and regulating qi, and promoting blood circulation and bone healing. It is mainly used for fractures, bruises, boils, carbuncles, and external bleeding. The flowers, bitter, slightly sweet, and cool in nature, have the effects of clearing heat and relieving pain, regulating menstruation and astringing leukorrhea. They are used for toothache, acute conjunctivitis, pharyngitis, irregular menstruation, and excessive leukorrhea. The roots, bitter and neutral in nature, have the effects of regulating qi and eliminating stagnation, promoting blood circulation and relieving pain, and detoxifying and reducing swelling. They are used for amenorrhea, stomach pain, and food stagnation. Currently, willowleaf lettuce is mainly used for hemostasis, menstrual disorders, prostate inflammation, and sleep problems. In addition, its young leaves are often used as food and feed.

[0004] Skin whitening mechanisms primarily involve several pathways, including direct whitening by reducing melanin content and antioxidant effects, with inhibiting melanin formation being the most common. Melanin is a large molecule ubiquitous in the human body, particularly in the eyes, skin, and pigmented tissues; its density determines tissue color. Melanin protects the skin from UV rays and free radical damage, but it also contributes to skin aging and pigmentation, leading to excessive melanin production and problems such as dullness and age spots. Skin aging results from complex interactions between the epidermis, dermis, subcutaneous fat, and extracellular substrates, causing pigmentation, wrinkle formation, cramps, and other oxidative stress-induced activities. Furthermore, skin aging leads to decreased hormone secretion, reducing skin cell activity and function. Tyrosinase is an essential enzyme in melanin production. Therefore, compounds with high antioxidant activity are expected to inhibit pigmentation by affecting the biosynthesis of melanin and tyrosinase, thereby promoting whitening and delaying aging.

[0005] Currently, the whitening products on the market are mainly classified into chemical, biological, and natural plant-based types. Among them, natural plant-based whitening agents are derived from natural plants, have good safety, and are abundant, readily available, and low in cost, thus becoming one of the main research directions in recent years. However, there are no reports of using willowherb extract in cosmetics. Summary of the Invention

[0006] In view of the above-mentioned prior art, the present invention provides a willowherb extract, its extraction method and application, to solve the technical problem of low extraction rate of effective components of willowherb, and to develop new uses for willowherb extract.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is to provide a method for extracting willowherb extract, comprising the following steps:

[0008] S1: Take fresh willow leaves, mix them with acetic acid solution at a ratio of 1g:5-10mL, grind them into a pulp to obtain a slurry;

[0009] S2: Mix the slurry with sodium chloride solution and ultrasonically vibrate for 10-20 minutes to obtain the mixture;

[0010] S3: Add methanol-hydrochloric acid mixed solution to the mixture, heat and reflux at 45-100℃ for 30-60 min, then filter and collect the filtrate;

[0011] S4: Add organic extractant to the filtrate, let stand for 30-45 minutes, centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain crude product;

[0012] S5: The crude product was purified using an XDA-5 macroporous resin column as the purification column and an ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0013] The beneficial effects of the above-mentioned technical solution of the present invention are as follows: When extracting willow leaves, the present invention first mixes and grinds them with acetic acid. Acetic acid can not only lower the pH value of the willow leaf cell system, causing the cell wall to dissociate and promoting the release and extraction of effective components, but also improve the stability of effective components such as polyphenols and reduce their sensitivity and the possibility of loss of activity.

[0014] After obtaining the slurry, a sodium chloride solution was added. The sodium chloride solution regulates the osmotic pressure of the willowherb cells, causing water molecules to flow out of the cells, leading to cell contraction and the release of intracellular components, thereby increasing the extraction rate of active ingredients. Additionally, sodium chloride increases the solubility of components such as quercetin, maximizing the dissolution of active ingredients in the extraction solvent. After adding the sodium chloride solution, ultrasound was performed. The rupture of microbubbles and the shock wave effect generated by ultrasound affect the cell wall structure, causing cell wall rupture and facilitating the release of target components. Ultrasound also increases the mass transfer rate of substances in the liquid phase, enhancing convection and diffusion, allowing the target components to be rapidly released from the plant tissue into the solvent.

[0015] After treatment with acetic acid and sodium chloride solution, the cell walls of *Salix viminalis* are essentially completely destroyed. Adding a methanol-hydrochloric acid mixture at this point allows the hydrochloric acid to alter the pH of the solution, thereby changing the ionic form or molecular structure of the active ingredients. This helps improve the solubility of the active ingredients, making them more readily soluble in the solvent. It can also convert some unstable compounds into stable forms, thus ensuring the content of the active ingredients. Furthermore, hydrochloric acid can further disrupt cell tissue, facilitating the release of active ingredients from within the cells. Methanol, as a solvent, effectively dissolves the active ingredients in *Salix viminalis*. Combined with the previous treatment, all the active ingredients in *Salix viminalis* are dissolved in methanol. Subsequent purification yields cosmetic-grade *Salix viminalis* extract.

[0016] Based on the above technical solution, the present invention can be further improved as follows.

[0017] Furthermore, the volume concentration of the acetic acid solution is 5-10%.

[0018] Furthermore, the concentration of the sodium chloride solution is 0.1–0.5 wt%, and the volume ratio of the slurry to the sodium chloride solution is 1:1–3.

[0019] Furthermore, the power of the ultrasonic oscillation is 200–300W, and the frequency is 25–40kHz.

[0020] Furthermore, the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixed solution is 3 to 5:1.

[0021] Furthermore, the volume ratio of the mixture to the methanol-hydrochloric acid mixed solution is 1:1 to 3.

[0022] Furthermore, the organic extractant is ethyl acetate, and the filtrate is mixed with ethyl acetate in equal volume.

[0023] Furthermore, the XDA-5 macroporous resin column uses XDA-5 macroporous resin as the packing material and has a size of 65*100mm; the volume fraction of the ethanol solution used for elution is 70%.

[0024] The present invention also discloses a willowherb extract obtained by the above extraction method.

[0025] Willowherb is rich in rutin, apigenin, quercetin, and other components, which can be effectively extracted using the extraction process described in this application. Apigenin, a natural plant flavonoid, has antioxidant properties, effectively scavenging free radicals, reducing oxidative stress, and inhibiting excessive melanin production. It also possesses anti-inflammatory properties, reducing the damage of inflammation to the skin and helping to soothe and alleviate pigmentation caused by sun exposure and environmental pollution, thus achieving a skin whitening effect. Rutin also has antioxidant and anti-inflammatory properties; it can reduce melanocyte activity and inhibit excessive melanin production, thereby helping to alleviate mild pigmentation problems. In addition to its antioxidant and anti-inflammatory effects, quercetin effectively inhibits tyrosinase activity. By inhibiting tyrosinase, quercetin can reduce melanin synthesis, thus helping to lighten age spots and brighten skin tone.

[0026] The willowherb extract extracted in this application contains a variety of active components with anti-inflammatory and antioxidant effects, which can effectively alleviate pigmentation caused by oxidative stress and inflammation, thereby producing a good whitening effect.

[0027] This invention also discloses the application of the above-mentioned willowherb extract in the preparation of cosmetics. The prepared cosmetics have excellent whitening effects and can be used as whitening cosmetics.

[0028] The beneficial effects of this invention are:

[0029] 1. By adjusting the extraction process, this application can fully extract the active ingredients from willow leaves, thus ensuring the yield of the extract.

[0030] 2. The extract obtained by the extraction method in this application contains a variety of whitening active ingredients, which can effectively relieve oxidative stress and inflammatory response, thereby reducing pigment deposition and achieving a whitening effect. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0032] Example 1

[0033] An extract of *Salix viminalis* is obtained through the following process:

[0034] S1: Take fresh willow leaf leaves, mix them with an 8% acetic acid solution at a ratio of 1g:8mL, and then beat them to obtain a pulp.

[0035] S2: Mix the slurry with a 0.3wt% sodium chloride solution at a volume ratio of 1:2, and ultrasonically vibrate for 15 minutes to obtain the mixture; the ultrasonic power is 250W and the frequency is 30KHz.

[0036] S3: Add a methanol-hydrochloric acid mixture to the mixture, heat under reflux at 60°C for 45 min, then filter and collect the filtrate; the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixture is 4:1, and the volume ratio of the mixture to the methanol-hydrochloric acid mixture is 1:2.

[0037] S4: Add an equal volume of ethyl acetate to the filtrate, shake for 2 minutes, let stand for 40 minutes, then centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain the crude product;

[0038] S5: The crude product was purified using an XDA-5 macroporous resin column as the purification column and a 70% (v / v) ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0039] Example 2

[0040] An extract of *Salix viminalis* is obtained through the following process:

[0041] S1: Take fresh willow leaf leaves, mix them with a 5% acetic acid solution at a ratio of 1g:5mL, and then beat them to obtain a pulp.

[0042] S2: Mix the slurry with a 0.1wt% sodium chloride solution at a volume ratio of 1:1, and ultrasonically vibrate for 20 minutes to obtain the mixture; the ultrasonic vibration power is 200W and the frequency is 25KHz.

[0043] S3: Add a methanol-hydrochloric acid mixture to the mixture, heat under reflux at 45°C for 60 min, then filter and collect the filtrate; the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixture is 3:1, and the volume ratio of the mixture to the methanol-hydrochloric acid mixture is 1:1.

[0044] S4: Add an equal volume of ethyl acetate to the filtrate, shake for 2 minutes, let stand for 30 minutes, then centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain the crude product;

[0045] S5: The crude product was purified using an XDA-5 macroporous resin column as the purification column and a 70% (v / v) ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0046] Example 3

[0047] An extract of *Salix viminalis* is obtained through the following process:

[0048] S1: Take fresh willow leaf leaves, mix them with a 10% acetic acid solution at a ratio of 1g:10mL, and then pulp them to obtain a pulp.

[0049] S2: Mix the slurry with a 0.5wt% sodium chloride solution at a volume ratio of 1:3, and ultrasonically vibrate for 10 minutes to obtain the mixture; the ultrasonic vibration power is 300W and the frequency is 40KHz.

[0050] S3: Add a methanol-hydrochloric acid mixture to the mixture, heat under reflux at 100°C for 30 min, then filter and collect the filtrate; the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixture is 5:1, and the volume ratio of the mixture to the methanol-hydrochloric acid mixture is 1:3.

[0051] S4: Add an equal volume of ethyl acetate to the filtrate, shake for 2 minutes, let stand for 45 minutes, then centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain the crude product;

[0052] S5: The crude product was purified using an XDA-5 macroporous resin column as the purification column and a 70% (v / v) ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0053] Comparative Example 1

[0054] An extract of *Salix viminalis* is obtained through the following process:

[0055] S1: Take fresh willow leaf leaves, mix them with a 0.3wt% sodium chloride solution at a material-to-liquid ratio of 1g:8mL, and then beat them to obtain a pulp.

[0056] S2: Ultrasonic oscillation of the slurry for 15 minutes yields a mixture; the ultrasonic oscillation power is 250W and the frequency is 30KHz.

[0057] S3: Add a methanol-hydrochloric acid mixture to the mixture, heat under reflux at 60°C for 45 min, then filter and collect the filtrate; the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixture is 4:1, and the volume ratio of the mixture to the methanol-hydrochloric acid mixture is 1:2.

[0058] S4: Add an equal volume of ethyl acetate to the filtrate, shake for 2 minutes, let stand for 40 minutes, then centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain the crude product;

[0059] S5: The crude product was purified using an XDA-5 macroporous resin column as the purification column and a 70% (v / v) ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0060] Comparative Example 2

[0061] An extract of *Salix viminalis* is obtained through the following process:

[0062] S1: Take fresh willow leaf leaves, mix them with an 8% acetic acid solution at a ratio of 1g:8mL, and then beat them to obtain a pulp.

[0063] S2: Add a methanol-hydrochloric acid mixture to the slurry, heat and reflux at 60°C for 45 min, then filter and collect the filtrate; the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixture is 4:1, and the volume ratio of slurry to methanol-hydrochloric acid mixture is 1:2.

[0064] S3: Add an equal volume of ethyl acetate to the filtrate, shake for 2 minutes, let stand for 40 minutes, then centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain the crude product;

[0065] S4: The crude product was purified using an XDA-5 macroporous resin column as the purification column and a 70% (v / v) ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0066] Comparative Example 3

[0067] An extract of *Salix viminalis* is obtained through the following process:

[0068] S1: Take fresh willow leaf leaves, mix them with an 8% acetic acid solution at a ratio of 1g:8mL, and then beat them to obtain a pulp.

[0069] S2: Mix the slurry with a 0.3wt% sodium chloride solution at a volume ratio of 1:2, and ultrasonically vibrate for 15 minutes to obtain the mixture; the ultrasonic power is 250W and the frequency is 30KHz.

[0070] S3: Add methanol solution to the mixture, heat under reflux at 60°C for 45 min, then filter and collect the filtrate; the volume fraction of methanol solution is 75%, and the volume ratio of mixture to methanol solution is 1:2;

[0071] S4: Add an equal volume of ethyl acetate to the filtrate, shake for 2 minutes, let stand for 40 minutes, then centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain the crude product;

[0072] S5: The crude product was purified using an XDA-5 macroporous resin column as the purification column and a 70% (v / v) ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0073] Comparative Example 4

[0074] An extract of *Salix viminalis* is obtained through the following process:

[0075] S1: Take fresh willow leaf leaves, mix them with water at a ratio of 1g:8mL, and then beat them to obtain a pulp.

[0076] S2: Add a methanol-hydrochloric acid mixture to the slurry, heat and reflux at 60°C for 45 min, then filter and collect the filtrate; the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixture is 4:1, and the volume ratio of slurry to methanol-hydrochloric acid mixture is 1:2.

[0077] S3: Add an equal volume of ethyl acetate to the filtrate, shake for 2 minutes, let stand for 40 minutes, then centrifuge, collect the upper organic layer, and concentrate until the volume no longer changes to obtain the crude product;

[0078] S4: The crude product was purified using an XDA-5 macroporous resin column as the purification column and a 70% (v / v) ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product.

[0079] Experimental Example 1: Extraction Yield

[0080] The yield of willowherb extract was calculated using the following formula, and the results are shown in Table 1.

[0081]

[0082] Table 1. Yield of Willowleaf Extract

[0083] Yield (%) Example 1 10.24 Example 2 9.60 Example 3 10.67 Comparative Example 1 7.36 Comparative Example 2 7.80 Comparative Example 3 8.28 Comparative Example 4 5.94

[0084] As can be seen from Table 1, the extraction yield using the extraction process described in this application is above 9.6%, while the extraction yields of the comparative examples all decreased. This is because:

[0085] Compared with Example 1, Comparative Example 1 did not undergo acetic acidification treatment, so the cell walls of the willowherb could not be effectively broken, and the stability of the active ingredients could not be guaranteed, resulting in a decrease in the yield of the final extract.

[0086] Compared with Example 1, Comparative Example 2 was not treated with sodium chloride, so the osmotic pressure of the willowherb cells could not be adjusted during the extraction process, making it difficult to fully release the effective components inside the cells, resulting in a decrease in the yield of the final extract.

[0087] Compared with Example 1, Comparative Example 3 only added methanol during heating and reflux, but lacked hydrochloric acid. As a result, the cell walls of the willowherb could not be further damaged, which led to the incomplete release of the internal active ingredients and thus a decrease in the yield of the extract.

[0088] Compared with Example 1, Comparative Example 4 used only a mixed solution of methanol and hydrochloric acid to extract willow leaves. The cell walls were difficult to break down, and the effective components inside the cells were difficult to release, resulting in a low yield of extract.

[0089] Experimental Example 2: Inhibition rate of extract on tyrosinase

[0090] 1. Solution preparation

[0091] Preparation of phosphate buffered saline (PBS): Accurately weigh 71.6 g of disodium hydrogen phosphate and 31.2 g of sodium dihydrogen phosphate, dissolve them thoroughly in deionized water, transfer them to 1000 mL volumetric flasks and dilute to volume to prepare a 0.2 mol / L solution. Mix them thoroughly in a 51:49 ratio and adjust the pH to 6.8.

[0092] Preparation of tyrosine solution: Accurately weigh 0.01g of tyrosinase into a 100mL volumetric flask, and dilute to volume with PBS solution.

[0093] Preparation of dopamine solution: Accurately weigh a certain amount of dopamine, first add a small amount of 0.1 mol / L hydrochloric acid to pre-dissolve it, and after complete dissolution, use PBS solution to prepare a 1.5 g / L dopamine solution, and store it at 4°C in the dark.

[0094] Preparation of sample solutions: The extracts obtained in the examples and comparative examples were prepared into 0.4 g / L sample solutions using PBS solution.

[0095] 2. Measurement Method

[0096] Add the PBS solution, sample solution, and tyrosinase solution to each test tube according to the reaction composition in Table 2, mix well, and react in a constant temperature water bath at 37°C for 10 min. Immediately add 1 mL of dopamine solution to each tube, mix well, and return to the water bath for another 5 min. Immediately measure A after 5 min of reaction. λ＝475 A was measured respectively C1 A C2 A T1 and A T2 Three parallel groups were tested. The inhibition rate of the extract against tyrosinase was calculated using the following formula:

[0097] Inhibition rate = [1-(A T1 -A T2 / A C1 -A C2 )]*100%

[0098] Wherein, C1 is the blank group, C2 is used for blank zeroing, T1 is the sample group, and T2 is used for sample zeroing.

[0099] Table 2 Composition of the reaction solution

[0100] reaction group PBS / mL test stock solution / mL Tyrosinase / mL C1 13 2 C2 15 T1 11 2 2 T2 13 2

[0101] The inhibition rate of the extract against tyrosinase is shown in Table 3.

[0102] Table 3. Inhibition rate of *Salix viminalis* extract on tyrosinase

[0103] Inhibition rate (%) Example 1 78.25 Example 2 76.56 Example 3 80.00 Comparative Example 1 67.24 Comparative Example 2 70.31 Comparative Example 3 72.44 Comparative Example 4 59.30

[0104] As can be seen from Table 3, the extract obtained by the extraction process in this application has a high inhibition rate against tyrosinase, which can significantly inhibit the production of melanin, thereby producing a good whitening effect.

[0105] The extraction process in the comparative example could not completely extract the active ingredients from the willowherb, resulting in a lower content of active ingredients. Consequently, the inhibition rate of tyrosinase was lower than that in the example, leading to a poorer whitening effect.

[0106] Experiment Example 3: Skin Whitening Effect

[0107] Seventy healthy subjects (35 men and 35 women) were recruited and divided into seven groups. Opaque tape with a 2cm diameter perforation was applied to the arms of each subject, and the affected area was then irradiated with ultraviolet light at a dose 1.5 times the minimum erythema dose to induce skin darkening. Following ultraviolet irradiation, extracts obtained from the examples and comparative studies were applied to the irradiated areas. Skin color was measured using a colorimeter (commercially available) two months later.

[0108] The effect of each extract is determined by establishing an "L" value, which represents skin lightness and darkness. In this invention, the "L" value is calibrated using a standard plate, and measurements are repeated multiple times in one area to uniformly measure the pigment deposition. The skin color difference (ΔL) between the start and end of extract application is calculated using the following formula:

[0109] ΔL = Brightness L two months after the experiment - Brightness L at the beginning of the experiment

[0110] The results are shown in Table 4.

[0111] Table 4. Whitening effect of willowherb extract

[0112] Whitening effect (ΔL) Example 1 2.95 Example 2 2.74 Example 3 3.02 Comparative Example 1 2.13 Comparative Example 2 2.18 Comparative Example 3 2.35 Comparative Example 4 1.55

[0113] As can be seen from Table 4, the extract obtained in the examples has excellent whitening effect and can effectively reduce melanin deposition. Although the extract obtained in the comparative examples also has a certain whitening effect, its whitening effect is significantly reduced compared to the extract in the examples due to the lower content of active ingredients.

[0114] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A method for extracting an extract from *Salix viminalis*, characterized in that, Includes the following steps: S1: Take fresh willow leaves, mix them with acetic acid solution at a material-to-liquid ratio of 1g:5~10mL, and grind them into a pulp to obtain a slurry; the volume concentration of the acetic acid solution is 5~10%; S2: Mix the slurry with a sodium chloride solution and ultrasonically vibrate for 10-20 minutes to obtain a mixture; the concentration of the sodium chloride solution is 0.1-0.5 wt%, and the volume ratio of the slurry to the sodium chloride solution is 1:1-3; S3: Add a methanol-hydrochloric acid mixture to the mixture, heat under reflux at 45~100℃ for 30~60 min, then filter and collect the filtrate; the volume ratio of methanol to hydrochloric acid in the methanol-hydrochloric acid mixture is 3~5:1; S4: Add an organic extractant to the filtrate, let it stand for 30-45 minutes, centrifuge, collect the upper organic layer, and concentrate it until the volume no longer changes to obtain the crude product; the organic extractant is ethyl acetate, and the filtrate is mixed with ethyl acetate in equal volume; S5: The crude product was purified using an XDA-5 macroporous resin column as the purification column and an ethanol solution as the eluent. The eluent was collected, concentrated, and dried to obtain the final product. The volume fraction of the ethanol solution was 70%.

2. The extraction method according to claim 1, characterized in that: The ultrasonic oscillation has a power of 200~300W and a frequency of 25~40KHz.

3. The extraction method according to claim 1, characterized in that: The volume ratio of the mixture to the methanol-hydrochloric acid mixed solution is 1:1~3.

4. The extract of *Salix viminalis* obtained by the extraction method according to any one of claims 1 to 3.

5. The application of the willowherb extract according to claim 4 in the preparation of cosmetics, wherein the cosmetics are whitening cosmetics.

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