Preparation method of efficient and stable mulberry root extract containing oxyresveratrol and application of mulberry root extract in relieving skin itching feeling

Abstract

The invention relates to a preparation method of an efficient and stable mulberry root extract containing oxyresveratrol and application of the mulberry root extract in relieving skin itching, and belongs to the technical field of cosmetics. The preparation method of the mulberry root extract containing oxyresveratrol comprises the following steps: drying and crushing mulberry roots and stems, adding the crushed mulberry roots and stems into an aqueous solution of a deep-eutectic solvent, carrying out ultrasonic extraction, collecting a product, centrifuging, and taking supernate, so as to obtain the mulberry root extract containing oxyresveratrol. According to the method, on the basis of a green solvent system composed of betaine and 1, 3-propylene glycol / ethyl lactate and in combination with mild ultrasonic conditions, oxyresveratrol is efficiently extracted from mulberry roots, so that the extraction rate is increased, and the risk of high-temperature oxidation is avoided. And the obtained extract not only can inhibit the itch receptor MRGPX1 for a long time, but also is suitable for sensitive skin due to removal of irritant components, has high efficiency and biocompatibility, breaks through environmental pollution and technical bottlenecks of a traditional method, and has a wide market application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of cosmetics, and particularly to a preparation method of a highly efficient and stable mulberry root extract containing oxyresveratrol and its application in relieving skin itching. Background Art

[0002] Oxyresveratrol is a natural derivative of resveratrol, which can be extracted from the bark and roots of mulberry. It has various biological activities and is a natural polyphenol compound with strong antioxidant, anti-inflammatory and tyrosinase inhibitory activities. It can show broad application potential in the fields of medicine, cosmetics and food through mechanisms such as scavenging free radicals, regulating inflammatory signaling pathways and blocking melanogenesis.

[0003] However, oxyresveratrol faces multiple challenges in practical applications: Firstly, the natural extraction of this component is difficult, mainly relying on limited sources such as Moraceae plants. The traditional extraction process is inefficient and costly; Secondly, its chemical properties are extremely unstable and are easily degraded by light, heat, oxygen and acid-base environments, resulting in the loss of activity; In addition, the problems of poor water solubility (almost insoluble in water) and low transdermal efficiency also severely limit the application effects of this component in cosmetics and pharmaceutical preparations. Conventional solutions such as spray drying embedding technology can partially improve stability, but have defects such as low encapsulation rate, insufficient loading rate and complex process, and polysaccharide wall materials are likely to cause poor skin feel.

[0004] In summary, there is an urgent need to develop a preparation method of oxyresveratrol with high extraction rate and high stability to meet the high market demand for oxyresveratrol. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a preparation method of a highly efficient and stable mulberry root extract containing oxyresveratrol and its application in relieving skin itching. In the present invention, an ultrasonic-assisted deep eutectic solvent method is adopted, based on a green solvent system composed of betaine and 1,3-propanediol / ethyl lactate, combined with mild ultrasonic conditions, to achieve the efficient extraction of oxyresveratrol from mulberry roots. This technology enhances the solubility and stability of the target component through the strong hydrogen bond action of the deep eutectic solvent. At the same time, the ultrasonic cavitation effect promotes the rupture of cell walls, improving the extraction rate and avoiding the risk of high-temperature oxidation. Moreover, the obtained extract can not only inhibit the itch receptor MRGPX1 for a long time, but also be suitable for sensitive skin due to the removal of irritating components, with both high efficiency and biocompatibility, breaking through the environmental pollution and technical bottlenecks of traditional methods.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a method for preparing a highly efficient and stable mulberry root extract containing oxyresveratrol, comprising the following steps:

[0008] Take the rhizome of mulberry tree, dry and crush it, then add it to an aqueous solution of a deep eutectic solvent for ultrasonic extraction. After the extraction is completed, collect the product and centrifuge it, and take the supernatant to obtain the mulberry root extract containing oxyresveratrol.

[0009] Among them, the aqueous solution of the deep eutectic solvent is composed of a hydrogen bond acceptor, a hydrogen bond donor and water; and the hydrogen bond acceptor includes at least one of betaine, choline chloride, glycine, L-proline; the hydrogen bond donor includes at least one of 1,3-propanediol, 1,2-propanediol, ethylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, oxalic acid, malic acid, lactic acid, ethyl lactate; preferably, the hydrogen bond acceptor is betaine, and the hydrogen bond donors are 1,3-propanediol and ethyl lactate.

[0010] Among them, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(2-5); preferably, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(3-4).

[0011] Among them, the total mass concentration of the hydrogen bond acceptor and the hydrogen bond donor in the deep eutectic solvent is 70-95%; preferably, the total mass concentration of the hydrogen bond acceptor and the hydrogen bond donor in the deep eutectic solvent is 85-90%.

[0012] Among them, the temperature of the ultrasonic extraction is 40-60 °C; and / or, the power of the ultrasonic extraction is 150-250 W, and the time of the ultrasonic extraction is 20-50 min; preferably, the temperature, power and time of the ultrasonic extraction are 50 °C, 200 W and 30 min respectively.

[0013] Among them, the solid-liquid ratio of the ultrasonic extraction is 1 g:(10-30) mL; preferably, the solid-liquid ratio of the ultrasonic extraction is 1 g:(15-20) mL

[0014] In a second aspect, the present invention provides a mulberry root extract containing oxyresveratrol obtained by the method for preparing a mulberry root extract containing oxyresveratrol as described in the first aspect.

[0015] In a third aspect, the present invention provides the application of the mulberry root extract containing oxyresveratrol as described in the second aspect in the preparation of cosmetics.

[0016] As a preferred embodiment of the third aspect, the cosmetics include one or more of lotion, emulsion, cream, facial mask, essence, spray.

[0017] Fourthly, the present invention provides an emulsion, which comprises components in the following mass percentages: a thickener 0.05-0.3%, a humectant 0.5-1%, a pH regulator 0.01-0.3%, an emulsifier 0.5-5%, a preservative 0.5-3%, the mulberry root extract containing oxyresveratrol 1-10%, and the balance being water.

[0018] As a preferred embodiment of the fourth aspect, the emulsifier includes at least one of triglyceride caprylate / caprate, C14-22 alcohol, C12-20 alkyl glucoside, cetearyl glucoside, isononyl isononanoate, polydimethylsiloxane, PEG-40 hydrogenated castor oil, stearyl alcohol, sucrose stearate, hydroxystearic acid, polymethylsilsesquioxane, pentaerythritol distearate, sucrose stearate, polydimethylsiloxane; and / or, the preservative includes at least one of p-hydroxyacetophenone, polyhydric alcohol; and / or, the thickener includes at least one of polyacrylate crosslinked polymer-6, carbomer, carrageenan, gellan gum, xanthan gum, microcrystalline cellulose, cellulose gum, ethyl cellulose, tara gum, guar gum, acryloyldimethyltaurate / VP copolymer; and / or, the humectant includes at least one of glycerol, D-panthenol, vitamin B5, 1,3-butanediol, 1,2-hexanediol, 1,3-propanediol, sodium hyaluronate, tremella polysaccharide, trehalose, betaine, allantoin, low molecular weight sodium hyaluronate; and / or, the pH regulator includes at least one of arginine, disodium ethylenediaminetetraacetate, tromethamine, EDTA disodium.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1) The present invention adopts an ultrasonic-assisted deep eutectic solvent method, based on a green solvent system composed of betaine and 1,3-propanediol / ethyl lactate, combined with mild ultrasonic conditions, to achieve the efficient extraction of oxyresveratrol from mulberry roots. This technology enhances the solubility and stability of the target component through the strong hydrogen bond action of the deep eutectic solvent. At the same time, the ultrasonic cavitation effect promotes the rupture of cell walls, improving the extraction rate and avoiding the risk of high-temperature oxidation.

[0021] 2) The inventors of the present invention conducted a large number of screenings and optimizations on the types and ratios of hydrogen bond acceptors and hydrogen bond donors in the deep eutectic solvent based on this specific part of mulberry roots, and finally determined a deep eutectic solvent composed of betaine and 1,3-propanediol / ethyl lactate and water. Experiments have shown that when the molar ratio of hydrogen bond acceptor to hydrogen bond donor in the solvent is 1:(2-5), the content and stability of oxyresveratrol in the mulberry root extract are relatively high.

[0022] 3) In the present invention, it is further verified by experiments that the obtained mulberry root extract can not only inhibit the itch receptor MRGPX1 for a long time, but also be applicable to sensitive skin due to the removal of irritating components, with both high efficiency and biocompatibility. It breaks through the environmental pollution and technical bottlenecks of traditional methods and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a mechanism diagram of resveratrol oxide blocking the transmission of itching signals by binding to the itch receptor MRGPRX1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0025] Other materials, reagents, etc. used in the examples can be obtained from commercial sources without special instructions.

[0026] Example 1 Preparation method of mulberry root extract containing resveratrol oxide

[0027] (1) Prepare the eutectic solvent:

[0028] Mix betaine, 1,3-propanediol, and ethyl lactate in a molar ratio of 1:3:1 to form a mixed solution. Take 90 g of the mixed solution and uniformly mix it with 10 g of deionized water to obtain the eutectic solvent; the molar ratio of hydrogen bond acceptor to hydrogen bond donor of this eutectic solvent is 1:4, and the total mass concentration is 90%.

[0029] (2) Preparation of mulberry root extract:

[0030] Collect the rhizomes of mulberry trees, clean them, put them in a constant temperature oven at 50 °C to dry to constant weight, grind and crush them, pass through an 80-mesh sieve, take 1 g after filtration and add it to the eutectic solvent prepared in step (1), with a solid-liquid ratio of 1 g:20 mL. Use ultrasonic extraction method, with an ultrasonic temperature of 50 °C, a power of 200 W, and an extraction time of 30 min. Collect the product and centrifuge it, and take the supernatant to obtain the mulberry root extract containing resveratrol oxide, and name the extract as Example 1.

[0031] Example 2 Preparation method of mulberry root extract containing resveratrol oxide

[0032] (1) Prepare the eutectic solvent:

[0033] Mix betaine, 1,3-propanediol, and ethyl lactate in a molar ratio of 1:2.5:0.5 to form a mixed solution. Take 85 g of the mixed solution and uniformly mix it with 15 g of deionized water to obtain the eutectic solvent; the molar ratio of hydrogen bond acceptor to hydrogen bond donor of this eutectic solvent is 1:3, and the total mass concentration is 85%.

[0034] (2) Preparation of mulberry root extract:

[0035] Collect the rhizomes of mulberry trees, clean them, put them in a constant temperature oven at 50 °C and dry to a constant weight, grind and crush them, sieve them through an 80-mesh sieve, take 1 g after filtration and add it to the eutectic solvent prepared in step (1), and the solid-liquid ratio is 1 g: 15 mL. Use ultrasonic extraction method, ultrasonic temperature 45 °C, power 220 W, extraction time 40 min, collect the product by centrifugation, and take the supernatant to obtain the mulberry root extract containing oxyresveratrol, and name the extract as Example 2.

[0036] Preparation method of mulberry root extract containing oxyresveratrol in Example 3

[0037] (1) Preparation of eutectic solvent:

[0038] Mix betaine, 1,3-propanediol, and ethyl lactate in a molar ratio of 1:4:1 to form a mixed solution, take 95 g of the mixed solution and mix it evenly with 5 g of deionized water to obtain a eutectic solvent; then the molar ratio of hydrogen bond acceptor to hydrogen bond donor of this eutectic solvent is 1:5, and the total mass concentration is 95%.

[0039] (2) Preparation of mulberry root extract:

[0040] Collect the rhizomes of mulberry trees, clean them, put them in a constant temperature oven at 50 °C and dry to a constant weight, grind and crush them, sieve them through an 80-mesh sieve, take 1 g after filtration and add it to the eutectic solvent prepared in step (1), and the solid-liquid ratio is 1 g: 30 mL. Use ultrasonic extraction method, ultrasonic temperature 60 °C, power 150 W, extraction time 50 min, collect the product by centrifugation, and take the supernatant to obtain the mulberry root extract containing oxyresveratrol, and name the extract as Example 3.

[0041] Preparation method of mulberry root extract containing oxyresveratrol in Example 4

[0042] (1) Preparation of eutectic solvent:

[0043] Mix betaine, 1,3-propanediol, and ethyl lactate in a molar ratio of 1:1.5:0.5 to form a mixed solution, take 80 g of the mixed solution and mix it evenly with 20 g of deionized water to obtain a eutectic solvent; then the molar ratio of hydrogen bond acceptor to hydrogen bond donor of this eutectic solvent is 1:2, and the total mass concentration is 80%.

[0044] (2) Preparation of mulberry root extract:

[0045] Collect the rhizomes of mulberry trees, wash them clean, place them in a constant temperature oven at 50 °C and dry to a constant weight, grind and pulverize them, sieve them through an 80-mesh sieve, take 1 g after filtration and add it to the eutectic solvent prepared in step (1), with a solid-liquid ratio of 1 g: 10 mL. Use ultrasonic extraction method, with an ultrasonic temperature of 40 °C, a power of 250 W, and an extraction time of 20 min. Centrifuge the collected product and take the supernatant to obtain the mulberry root extract containing oxyresveratrol, and name the extract as Example 4.

[0046] Comparative Example 1

[0047] Compared with the preparation method of Example 1, only the choice of hydrogen bond acceptor is different, that is, choline chloride is used instead of betaine, and the remaining steps are exactly the same as those of Example 1.

[0048] Comparative Example 2

[0049] Compared with the preparation method of Example 1, only the choice of hydrogen bond donor is different, that is, 1,3-propanediol is not added, and an equal amount of ethyl lactate is used to make up the missing amount, and the remaining steps are exactly the same as those of Example 1.

[0050] Comparative Example 3

[0051] Compared with the preparation method of Example 1, only the choice of hydrogen bond donor is different, ethyl lactate is not added, and an equal amount of 1,3-propanediol is used to make up the missing amount, and the remaining steps are exactly the same as those of Example 1.

[0052] Comparative Example 4

[0053] Compared with the preparation method of Example 1, only the choice of hydrogen bond donor is different, and butanediol is used instead of 1,3-propanediol and ethyl lactate, and the remaining steps are exactly the same as those of Example 1.

[0054] Comparative Example 5

[0055] Compared with the preparation method of Example 1, only the molar ratio of hydrogen bond acceptor and hydrogen bond donor is different. Betaine, 1,3-propanediol, and ethyl lactate are mixed in a molar mass ratio of 1:0.75:0.25 (i.e., the molar ratio of hydrogen bond acceptor and hydrogen bond donor is 1:1), and the remaining steps are exactly the same as those of Example 1.

[0056] Comparative Example 6

[0057] Compared with the preparation method of Example 1, only the molar ratio of hydrogen bond acceptor and hydrogen bond donor is different. Betaine, 1,3-propanediol, and ethyl lactate are mixed in a molar mass ratio of 1:4.5:1.5 (i.e., the molar ratio of hydrogen bond acceptor and hydrogen bond donor is 1:6), and the remaining steps are exactly the same as those of Example 1.

[0058] Comparative Example 7

[0059] Compared with the preparation method of Example 1, only the material-liquid ratio, ultrasonic temperature, power, and extraction time in the preparation method of mulberry root extract are different. The material-liquid ratio in this comparative example is 1 g:5 mL, the ultrasonic temperature is 30 °C, the power is 100 W, and the extraction time is 10 min. The remaining steps are exactly the same as those in Example 1.

[0060] Comparative Example 8

[0061] Compared with the preparation method of Example 1, only the material-liquid ratio, ultrasonic temperature, power, and extraction time in the preparation method of mulberry root extract are different. The material-liquid ratio in this comparative example is 1 g:40 mL, the ultrasonic temperature is 70 °C, the power is 300 W, and the extraction time is 60 min. The remaining steps are exactly the same as those in Example 1.

[0062] Comparative Example 9

[0063] Collect the rhizomes of mulberry trees, clean them, put them in a constant temperature oven at 50 °C and dry to constant weight, grind and crush them, pass through an 80-mesh sieve, filter, take 1 g and add it to an aqueous solution with 75% mass percentage of ethanol, and the material-liquid ratio is 1 g:20 mL; use ultrasonic extraction method, the ultrasonic temperature is 50 °C, the power is 200 W, the extraction time is 30 min, collect the product by centrifugation, and take the supernatant to obtain it.

[0064] Comparative Example 10

[0065] Compared with the preparation method of Example 1, only the extraction part is different, that is, the branches of mulberry trees are used to replace the rhizomes, and the remaining steps are exactly the same as those in Example 1.

[0066] Effect experiment

[0067] 1) Detect the content and stability of oxyresveratrol in examples and comparative examples by high performance liquid chromatography

[0068] Detection of oxyresveratrol content: Precisely measure 1 mL of the prepared mulberry root extract, dilute it in 9 mL of methanol, filter through a 0.22 μm filter membrane, and then use high performance liquid chromatography to determine the oxyresveratrol content in the extract. Use a standard product of oxyresveratrol (purchased from Yuanye Bio, product number B21467) to prepare standard solutions with gradient concentrations, draw a standard curve, and calculate the oxyresveratrol content M0 in the sample according to the standard curve formula. The chromatographic column used is a C18 column (100 mm × 2.1 mm, 3 μM), the mobile phase is 60% methanol, the flow rate is 0.5 mL / min, and the sample injection volume is 10 μL.

[0069] Stability test: Measure 5 mL of the mulberry root extracts prepared in the examples and comparative examples respectively into 10 mL transparent sealed PE bottles, and place them at temperatures of 4°C, 25°C, and 50°C respectively, with 15W light illumination. Then, detect the mass M1 of resveratrol oxide on the 7th day. The detection method is the same as M0. Subsequently, calculate the retention rate of resveratrol oxide. The retention rate of resveratrol oxide = M1 / M0 × 100%.

[0070] The results are shown in Table 1:

[0071] Table 1 Results of resveratrol oxide content and stability test

[0072]

[0073] It can be seen from the results in Table 1 that: 1) By comparing the results of the examples with those of Comparative Examples 1-4 and 9, it can be seen that the preparation method of this application is significantly better than the alcohol extraction method, and the components in the deep eutectic solvent have a greater impact on the extraction efficiency and stability of resveratrol oxide. The deep eutectic solvent composed of betaine, 1,3-propanediol, and ethyl lactate makes the content and stability of resveratrol oxide in the prepared mulberry root extract relatively high, producing unexpected technical effects; 2) By comparing the results of the examples with those of Comparative Examples 5-6, it can be learned that the molar ratio of hydrogen bond acceptor to hydrogen bond donor also affects the extraction efficiency and stability of resveratrol oxide. The experiments of this application prove that the molar ratio of hydrogen bond acceptor to hydrogen bond donor has better experimental effects within the range of 1:2-5; 3) By comparing the results of the examples with those of Comparative Examples 7-8, it can be learned that the solid-liquid ratio in the preparation process, as well as the temperature, power, and extraction time of ultrasonic waves, will all have a certain impact on the extraction efficiency and stability of resveratrol oxide; 4) By comparing the results of the examples with those of Comparative Example 10, it shows that both mulberry roots and mulberry branches are commonly used sources for extracting resveratrol oxide in this field. The inventor previously screened and optimized the types and ratios of hydrogen bond acceptors and hydrogen bond donors in the deep eutectic solvent based on this specific part of mulberry roots. Finally, a deep eutectic solvent composed of betaine and 1,3-propanediol / ethyl lactate and water was determined. Moreover, the content and stability of resveratrol oxide in the mulberry branch extract prepared with the solvent in this application are quite different from those in the mulberry root extract, indicating that even for different parts of the same plant, due to the different compositions of different parts, the deep eutectic solvent is not universal. The experiments of this invention prove that the deep eutectic solvent composed of betaine and 1,3-propanediol / ethyl lactate and water is only applicable to efficiently extract resveratrol oxide from mulberry roots.

[0074] Application examples

[0075] An emulsion is provided, and the components (mass percentage) of the emulsion are shown in Table 2; among them, the mulberry root extracts containing resveratrol used in Application Examples 1-4 are respectively the mulberry root extracts containing resveratrol prepared in Examples 1-4, and the mulberry root extracts containing resveratrol used in Application Examples 5-6 are the mulberry root extracts containing resveratrol prepared in Example 1; the mulberry root extracts containing resveratrol used in Comparative Application Examples 1-9 are respectively the mulberry root extracts containing resveratrol prepared in Comparative Examples 1-9; in addition, a blank application example is set, and the only difference between the blank application example and Application Example 1 is that the mulberry root extract containing resveratrol is not added.

[0076] Table 2 Component composition of the emulsion (mass percentage)

[0077]

[0078] This application example provides a preparation method of an emulsion, and the preparation method includes the following steps:

[0079] (1) Mix a humectant, a thickener, and a part of the pH regulator (EDTA-disodium) with water and stir. After heating to 85 °C, homogenize at a rotation speed of 1300 rpm for 4 min. After the homogenization is completed, keep it warm for standby to obtain a prefabricated Phase A;

[0080] (2) Mix the emulsifiers, heat to 75 °C, and then homogenize at a rotation speed of 1300 rpm for 4 min. After the homogenization is completed, keep it warm for standby to obtain a prefabricated Phase B;

[0081] (3) Mix the preservatives, heat to 60 °C to melt, and obtain a prefabricated Phase C;

[0082] (4) Heat the prefabricated Phase A to 80 °C, add the prefabricated Phase B at a rotation speed of 300 rpm, stir and mix. Then cool down to 60 °C, add the prefabricated Phase C at a rotation speed of 300 rpm and stir and mix. Subsequently, cool down to below 45 °C, add the mulberry root extract containing resveratrol and continue to stir for 8 min. Finally, add the remaining pH regulator (arginine) to adjust the pH to 5.5 - 7.0, then stop stirring, discharge, and obtain the emulsion.

[0083] 2. Effects of Application Examples 1-6 and Comparative Application Examples 1-9 on the mouse itching model

[0084] Experimental animals: 128 SPF-grade ICR mice, 5 - 6 weeks old, weighing 20 - 25 g, with half males and half females, provided by the Guangdong Provincial Experimental Animal Center, randomly divided into 16 groups, with 8 mice in each group.

[0085] Experimental method: After 1 week of adaptive feeding, cut the hair on the backs of all mice with scissors, and then wash it clean with depilatory cream.

[0086] Expose the skin to form an area of approximately 2 cm × 2 cm. After 24 h, apply the emulsions prepared in Application Examples 1 - 6, Comparative Application Examples 1 - 9, and Blank Application Example, 0.2 g each, to the surface of the nude skin of mice once a day for 7 consecutive days. 30 min after the last application, inject 0.01 mL / g of the pruritogenic peptide BAM8 - 22 solution (prepared with 0.01% BAM8 - 22 solution in physiological saline) subcutaneously at the center of the depilated area on the back of all mice, and immediately observe and record the scratching times of the mice within 10 min (counting one scratching when the mouse scratches continuously until a short pause occurs).

[0087] The pruritogenic peptide BAM8 - 22 is an agonist of the itch receptor MRGPRX1. By binding to and activating the itch receptor, it triggers the transmission of itch signals, resulting in the generation of itching sensations. However, in actual operation, the inventor found that resveratrol oxide can competitively bind to the active pocket of the itch receptor MRGPRX1 (see Appendix Figure 1 ), thereby inhibiting the itch signal induced by the pruritogenic peptide BAM8 - 22 and achieving the effect of reducing itching sensations.

[0088] The results are shown in Table 3 as follows:

[0089] Table 3

[0090]

[0091]

[0092] The results in Table 3 show that the average scratching times in Application Examples 1 - 6 are lower than those in Comparative Application Examples 1 - 9, indicating that the average scratching times of mice are positively correlated with the content of resveratrol oxide in the mulberry root extract. It also indirectly verifies that resveratrol oxide can inhibit the itch signal induced by the pruritogenic peptide BAM8 - 22 and can achieve the effect of reducing itching sensations.

[0093] 3. Human skin patch test.

[0094] Recruit 30 volunteers, 15 males and 15 females, aged 20 - 50 years. Using the closed patch test method, place an equal amount (0.020 mL - 0.025 mL) of the test samples (emulsions prepared in Application Examples 1 - 6, Comparative Application Examples 1 - 9, and Blank Application Example) in a specific patch tester, apply it to the arms of the volunteers with a low - sensitization tape, gently press to make it evenly adhere to the skin, and leave it for 24 h; the blank control group is distilled water, and the blank application example is to use an emulsion without mulberry root extract. After 24 h, remove the patch tester, and observe the skin reactions at 0.5 h, 24 h, and 48 h and record the results. The adverse reaction grades of the skin are shown in Table 4 below.

[0095] Table 4

[0096]

[0097] After testing, the emulsions provided by Application Examples 1-6 and Comparative Application Examples 1-9 of the present invention were all negative reactions after human patch testing, and they are safe and non-irritating to human skin.

[0098] 4. Human efficacy test of the composition for soothing skin itching

[0099] Experimental method: According to the "Technical Specifications for Cosmetics Safety" (2015), 96 Asian adult testers aged 18-60 who consciously have itchy and sensitive skin were selected and randomly divided into 16 groups with 6 people in each group. The volunteers applied the samples (the emulsions prepared from Application Examples 1-6, Application Comparative Examples 1-9, and Blank Application Examples) on the whole face once in the morning and once in the evening every day, and data was collected when they visited on the 0th day and the 28th day. After the volunteers visited, they washed their faces with facial cleanser, sat quietly in an air-conditioned room at a temperature of 21±1°C and a humidity of 50±10% for 30 minutes, filled out a subjective sensory questionnaire, and evaluated the current facial itching level with 0-9 points. The higher the score, the higher the itching level, 0 points means no feeling, and 9 points means unbearable.

[0100] The results obtained are shown in Table 5.

[0101] Table 5

[0102] Average itching score on day 0 Average itching score on day 28 Blank application example 7.2 7.2 Application example 1 7.2 0.8 Application example 2 7.3 1.2 Application example 3 7.0 1.3 Application example 4 7.3 1.7 Application example 5 7.2 1.5 Application example 6 7.0 1.0 Comparative application example 1 7.3 5.8 Comparative application example 2 7.2 6.3 Comparative application example 3 7.3 6.2 Comparative application example 4 7.0 6.7 Comparative application example 5 7.0 5.5 Comparative application example 6 7.2 5.8 Comparative application example 7 7.3 5.2 Comparative application example 8 7.3 5.2 Comparative application example 9 7.2 6.8

[0103] The results in Table 3 show that the average itching score of Application Examples 1-6 is lower than that of Comparative Application Examples 1-9, indicating that the emulsion containing the mulberry root extract containing oxyresveratrol obtained by the preparation method of the present application has a better effect of soothing skin itching.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a mulberry root extract containing oxidized resveratrol, characterized in that: The following steps are involved: The rhizome of mulberry tree is dried and crushed, and then added to an aqueous solution of a low eutectic solvent for ultrasonic extraction. After the extraction is completed, the product is collected and centrifuged to obtain the supernatant, thereby obtaining a mulberry root extract containing oxidized resveratrol; The aqueous solution of the deep eutectic solvent consists of a hydrogen bond acceptor, a hydrogen bond donor and water; The hydrogen bond acceptor is betaine, the hydrogen bond donors are 1,3-propylene glycol and ethyl lactate, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:2-5.

2. The preparation method according to claim 1, characterized in that The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:3-4.

3. The preparation method according to claim 1 or 2, characterized in that: The total mass concentration of hydrogen bond acceptors and hydrogen bond donors in the low eutectic solvent is 70-95%.

4. The preparation method according to claim 3, characterized in that: The total mass concentration of hydrogen bond acceptors and hydrogen bond donors in the low eutectic solvent is 85-90%.

5. The preparation method according to claim 1 or 2, characterized in that: The temperature of the ultrasonic extraction is 40-60° C., the power of the ultrasonic extraction is 150-250 W, and the time of the ultrasonic extraction is 20-50 min. The material-liquid ratio of the ultrasonic extraction is 1 g: (10-30) mL.

6. The preparation method according to claim 5, characterized in that: The temperature of the ultrasonic extraction is 50° C., the power of the ultrasonic extraction is 200 W, and the time of the ultrasonic extraction is 30 min. The material-liquid ratio of the ultrasonic extraction is 1 g: (15-20) mL.

7. The mulberry root extract containing oxidized resveratrol obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the mulberry root extract containing oxidized resveratrol according to claim 7 in the preparation of cosmetics, wherein the cosmetics include one or more of lotions, emulsions, creams, facial masks, essences, and sprays.

9. An emulsion, characterized in that The emulsion comprises the following components in percentage by mass: 0.05-0.3% thickener, 0.5-1% moisturizer, 0.01-0.3% pH regulator, 0.5-5% emulsifier, 0.5-3% preservative, 1-10% mulberry root extract containing oxidized resveratrol as claimed in claim 7, and the balance water.

10. The emulsion according to claim 9, characterized in that The emulsifier includes at least one of caprylic / capric triglyceride, C14-22 alcohol, C12-20 alkyl glucoside, cetearyl glucoside, isononyl isononanoate, dimethicone, PEG-40 hydrogenated castor oil, stearyl alcohol, sucrose stearate, hydroxystearic acid, polymethyl silsesquioxane, pentaerythrityl distearate, sucrose stearate, and dimethicone; The preservative includes at least one of p-hydroxyacetophenone and polyol; The thickener comprises at least one of polyacrylate cross-linked polymer-6, carbomer, carrageenan, gellan gum, xanthan gum, microcrystalline cellulose, cellulose gum, ethyl cellulose, taro gum, guar gum, and ammonium acryloyldimethyltaurate / VP copolymer; The moisturizing agent includes at least one of glycerin, D-panthenol, vitamin B5, 1,3-butylene glycol, 1,2-hexanediol, 1,3-propylene glycol, sodium hyaluronate, tremella polysaccharide, trehalose, betaine, allantoin, and low-molecular sodium hyaluronate; The pH regulator includes at least one of arginine, disodium EDTA, tromethamine, and disodium EDTA.

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