Skin care products, skin quality improvers and sunscreens

Abstract

To provide a topical skin preparation that enables the conversion of shikonin derivatives, which are poorly soluble in water and chemically unstable, into a stable water nano dispersion, effectively exhibiting the pharmacological activity of the shikonin derivatives, wherein the topical skin preparation also serves as a skin texture improver or a sunburn inhibitor.SOLUTION: A topical skin preparation comprises an aqueous dispersion comprising shikonin derivatives, hydrolyzed tannins, and oily components, aqueously dispersed with an acryloyl dimethyl taurine-based polymer dispersant. The topical skin preparation also serves as a skin texture improver or a sunburn inhibitor.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an external skin preparation containing a chemically unstable shikonin derivative, which is poorly soluble in water, as a stable aqueous dispersion, and to a skin quality improving agent and sunscreen comprising said external skin preparation. [Background technology]

[0002] Shikonin derivatives are red pigments found in the roots of plants of the Boraginaceae family, and include shikonin, shown in chemical formula 1 below, its acylated derivatives (acetylshikonin, isobutylshikonin, β,β-dimethylacrylshikonin, β-hydroxyisovalerylshikonin, isovalerylshikonin, etc.), dehydroshikonin, deoxyshikonin, etc., and their optical isomers.

[0003] [ka]

[0004] These shikonin derivatives possess antibacterial, antiviral (including against the novel coronavirus), antiallergic, and anti-inflammatory properties. However, they are unstable and decompose relatively easily when left in solution, which poses a significant limitation: they must be stored in a cool, dark place. For this reason, numerous studies have been conducted on stabilizers for shikonin derivatives. For example, UV absorbers, sulfur compounds such as cysteine, antioxidants such as butylhydroxytoluene, and saponins have been proposed, but none of them have produced satisfactory results.

[0005] Furthermore, Patent Document 1 below describes stabilization of hydroquinone with glucoside, but still fails to achieve satisfactory results. Meanwhile, Patent Document 2 below describes a method of stabilizing shikonin derivatives with tannin. Tannins have a certain stabilizing effect, but condensed tannins are generally darkly colored and have insufficient effects, making them unsuitable for use in topical skin preparations. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-013487 [Patent Document 2] Patent No. 2562344 Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to provide an external skin preparation, a skin quality improving agent and a sunscreen agent which are obtained by chemically and light-stabilizing a shikonin derivative, which is poorly soluble in water and chemically unstable, and by nano-dispersing it in an aqueous medium so that the pharmacological activity of the shikonin derivative can be effectively exerted, and which further have skin quality improving effects and sunscreen effects. [Means for solving the problem]

[0008] That is, one aspect of the present invention is to provide an external skin preparation containing an aqueous dispersion in which a shikonin derivative, a hydrolyzable tannin, and an oily component are dispersed in an aqueous solution using a polymer dispersant whose monomer is acryloyldimethyltaurate salt. In the topical skin preparation of the present invention, the shikonin derivative is preferably a shikonin derivative contained in the roots of Boraginaceae plants or an optical isomer thereof. Furthermore, the hydrolyzable tannin is preferably tara tannin, gallnut tannin (tannic acid), chestnut tannin, myraborum tannin, oak tannin, or tea tannin. Furthermore, the polymer dispersant containing the acryloyldimethyltaurate salt as a monomer is preferably a polyacryloyldimethyltaurate salt, or a polymer dispersant obtained by copolymerizing an acryloyldimethyltaurate salt with an acrylic acid derivative, a methacrylic acid derivative, or vinylpyrrolidone. Another aspect of the present invention is to provide a skin quality improving agent comprising the above-mentioned external skin preparation. A further aspect of the present invention provides a sunscreen comprising the above-mentioned external preparation for skin. [Effects of the Invention]

[0009] According to the present invention, a chemically unstable shikonin derivative is stabilized by hydrolyzable tannin, and further, an aqueous dispersion of shikonin nano-dispersed in an aqueous medium using a polymer dispersant with acryloyldimethyltaurate as a monomer together with an oily component is provided, thereby providing a topical skin preparation that can stably retain the shikonin derivative.Furthermore, a skin quality improving agent and a sunscreen agent comprising the above topical skin preparation can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] Photographs of shikonin nanodispersions #1, #2, and #3 prepared in Examples 4, 5, and 6. DETAILED DESCRIPTION OF THE INVENTION

[0011] The shikonin derivatives of the present invention are various red pigments found in the roots of the Boraginaceae plants Lithospermum Erythrorhizon and Lithospermum Officinale, and include alkanine, an optical isomer of shikonin, and its derivatives. Specifically, as mentioned above, these include shikonin, its acylated derivatives (acetylshikonin, isobutylshikonin, β,β-dimethylacrylshikonin, β-hydroxyisovalerylshikonin, isovalerylshikonin, etc.), dehydroshikonin, deoxyshikonin, etc., and their optical isomers. The shikonin derivatives can be used alone or in mixtures.

[0012] There is no particular limitation on the content of shikonin derivative in the present invention, but for example, in the case of common topical skin preparations such as lotions, serums, creams, and gels, it is preferably 0.005 to 0.3 mass%, and particularly preferably 0.01 to 0.2 mass%.

[0013] The most common method for extracting shikonin derivatives from plant sources involves drying and crushing the natural source and extracting it with water-miscible solvents such as water, ethanol, n-propanol, isopropanol, propylene glycol, and 1,3-butanediol, or water-immiscible solvents such as ethyl acetate, n-hexane, and n-heptane. Mixing these solvents can also be used. Oily components such as vegetable oils and squalane can also be used. Crude extracts from plants often contain components other than pigments. These crude extracts can be purified as needed to obtain highly purified pigment-containing products.

[0014] The hydrolyzable tannin of the present invention means a tannin that generates gallic acid upon hydrolysis among various tannins. The etymology of the word tannin comes from "tanning." The tanning effect of turning rawhide into leather is based on the interaction between the collagen in the rawhide and tannin (forming a sparingly soluble complex film on the surface). Tannins are a group of natural polyphenols that exhibit a strong affinity for high molecular weight compounds such as proteins and polysaccharides, basic compounds such as alkaloids, and heavy metals, and have the property of readily forming complexes with these. Tannins include condensed tannins and hydrolyzable tannins. Of these, hydrolyzable tannins liberate gallic acid upon hydrolysis and are the preferred tannins in this invention. (Reference: Journal of the Society of Organic Synthetic Chemistry, 2004, 62, 94-101)

[0015] In the present invention, preferred hydrolyzable tannins include tara tannin, oak gall tannin (tannic acid), chestnut tannin, miraboleum tannin, oak tannin, and tea tannin. Particularly preferred hydrolyzable tannins are tara tannin represented by the following chemical formula 2 and oak gall tannin (tannic acid) represented by the following chemical formula 3. Tara tannin is a hydrolyzable tannin extracted from the fruit pods of the legume plant called tara (scientific name: Caesalpinia spinosa Kuntze, English: Tara, Spanish: Tara) which grows in Peru in South America. Oak gall tannin is a hydrolyzable tannin obtained from dried galls formed by bites by an aphid (the oak gall aphid) on the deciduous tree of the Anacardiaceae family, the oak tree, and plants of the same genus. Both are mixtures of many compounds.

[0016] [ka]

[0017] In the present invention, the content of hydrolyzable tannins (such as tara tannins and tannic acid) is not particularly limited, but in the case of the form of lotion, serum, cream, or gel, for example, it is preferably 0.01 to 5% by mass, and particularly preferably 0.05 to 3.0% by mass.

[0018] In the present invention, a stable nano-dispersion can be obtained by dissolving the hydrophobic shikonin derivative in an oil component and then dispersing it in an aqueous medium with a polymer dispersant. The oil component can be a synthetic oil component or a natural oil component.

[0019] Synthetic oily components useful in the present invention include the following: Glyceryl tricaprylate, cetyl 2-ethylhexanoate, glyceryl tri-2-ethylhexanoate, isocetyl octanoate, isononyl isononanoate, ethylene glycol dioctanoate, caprylic / capric triglyceride, isopropyl myristate, isocetyl myristate, cetyl palmitate, dialkyl acetylated lanolin carbonate, lanolin acetate, isocetyl isostearate, hexyldecyl isostearate, cholesteryl isostearate, octyldodecyl erucate, cetyl octanoate, cetyl 2-ethylhexanoate, cetostearyl octanoate, cetostearyl 2-ethylhexanoate, cetostearyl isooctanoate, octyldodecyl oleate, decyl oleate, hexyldecyl dimethyloctanoate, isocetyl stearate, stearyl Examples of hydroxypropyl acrylate include hexyldecyl phosphate, cholesteryl stearate, butyl stearate, α-hydroxy fatty acid cholesteryl, glycerin trimyristate, cetyl lactate, myristyl lactate, isopropyl palmitate, cholesterol hydroxystearate, hexyldecanol, isotridecyl myristate, isopropyl myristate, octyldodecyl myristate, myristyl myristate, hexyl laurate, isopropyl lanolate, cholesteryl lanolate, and diisostearyl malate.

[0020] Natural oily ingredients useful in the present invention include: Argan oil, coconut oil, flaxseed oil, horse oil, squalane, squalene, olive oil, camellia oil, wheat germ oil, jojoba oil, avocado oil, carrot oil, palm oil, lanolin, egg yolk oil, clove oil, rosehip oil, lavender oil, peppermint oil, spearmint oil, orange oil, grapefruit oil, lemongrass oil, rosemary oil, ginger oil, patchouli oil, almond oil, cucumber oil, kukui nut oil, grapeseed oil, hydrogenated castor oil, sesame oil, rice germ oil, rice bran oil, safflower oil, soybean oil, evening primrose oil, corn oil, Rapeseed oil, apricot kernel oil, peach kernel oil, Job's tears oil, palm kernel oil, castor oil, sunflower oil, hazelnut oil, macadamia nut oil, meadowhoo oil, coconut oil, peanut oil, orange roughy oil, beef tallow, spermaceti, hydrogenated egg yolk oil, turtle oil, mink oil, etc.

[0021] Oily components that are particularly useful in the present invention are vegetable oils that are rich in unsaturated fatty acids, and specific examples include argan oil, linseed oil, olive oil, grapeseed oil, sesame oil, rice germ oil, rice bran oil, safflower oil, soybean oil, corn oil, rapeseed oil, and sunflower oil.

[0022] In the present invention, the oily component may be used alone or in combination. There are no particular restrictions on the content of the oily component, but in the case of the form of, for example, a beauty serum, cream, or gel, the content is preferably 0.1 to 8.0% by mass, and particularly preferably 0.2 to 4.0% by mass.

[0023] Next, we will discuss polymeric dispersants useful in the present invention. The polymeric dispersants useful in the present invention are polyacryloyldimethyltaurate salts or polymeric dispersants obtained by copolymerizing acryloyldimethyltaurate salts with acrylic acid derivatives, methacrylic acid derivatives, or vinylpyrrolidone. The inventors first attempted to disperse shikonin derivatives using various anionic and nonionic low-molecular-weight surfactants. While dispersion was possible at low shikonin concentrations of 0.01 mass percent or less, dispersion stability was insufficient at higher concentrations. Furthermore, cationic low-molecular-weight surfactants were able to disperse shikonin derivatives at higher concentrations, but the problem of the shikonin derivatives themselves being prone to decomposition became apparent.

[0024] On the other hand, in the case of the polyacryloyldimethyltaurate salt of the present invention or the polymer dispersant obtained by copolymerizing the acryloyldimethyltaurate salt with an acrylic acid derivative, a methacrylic acid derivative, or vinylpyrrolidone, a gel network is rapidly formed by adding water to the polymer dispersant, and emulsification, dispersion, and thickening occur simultaneously, enabling stable nano-dispersion of highly concentrated oily components.

[0025] Next, polymeric dispersants containing acryloyldimethyltaurine salt as a comonomer will be described in detail. In the present invention, polymeric dispersants obtained by polymerizing acryloyldimethyltaurine salt alone, as well as polymers obtained by copolymerizing acryloyldimethyltaurine salt with various vinyl monomers, are used. As the acryloyldimethyltaurine salt, sodium acryloyldimethyltaurine, potassium acryloyldimethyltaurine, ammonium acryloyldimethyltaurine, DEA acryloyldimethyltaurine, etc. are preferably used.

[0026] As the comonomer to be copolymerized with acryloyldimethyltaurate, various vinyl monomers can be used, but acrylic acid derivatives, methacrylic acid derivatives and vinylpyrrolidone are preferably used.As the acrylic acid derivative, acrylic acid and its salts, acrylic acid esters such as hydroxyethyl acrylate, acrylamide, N-hydroxyethylacrylamide and other acrylamides are more preferably used.As the methacrylic acid derivative, methacrylic acid esters are preferably used.

[0027] The molar ratio when copolymerizing the acryloyldimethyltaurate salt used in the present invention with an acrylic acid derivative, a methacrylic acid derivative, or vinylpyrrolidone can be selected arbitrarily within the range of 1:10 to 10:1.

[0028] In the present invention, the amount of polymer dispersant added is preferably 0.05 to 5 mass percent, particularly preferably 0.1 to 3 mass percent, based on the weight of the external skin preparation.

[0029] The topical skin preparation of the present invention comprises the above-mentioned shikonin derivative, hydrolyzed tannin, oily component, and acryloyldimethyltaurine-based polymer dispersant, and is formulated in a dosage form suitable for application to various skin areas of the face and body. The uses of the topical skin preparation of the present invention are not particularly limited, and specific examples include lotions, creams, emulsions, packs, foundations, beauty serums, cosmetic oils, ointments, gels, deodorants, hair growth tonics, body lotions, and body creams.

[0030] When formulating the topical skin preparation of the present invention, bases and additives can be used appropriately depending on the dosage form and shape. Examples of bases and additives used in the topical skin preparation of the present invention include humectants, thickeners, animal and plant extracts, amino acids, waxes, preservatives, whitening agents, UV absorbers, sequestering agents, pH adjusters, vitamins, skin conditioning agents, anti-inflammatory agents, dyes and pigments, and fragrances, and can be incorporated within a range that does not impair the effects of the present invention. Specific examples of bases and additives are listed below.

[0031] <Wetting agent> Glycerin, diglycerin, propylene glycol, 1,3-butanediol, isoprene glycol, pentanediol, dipropylene glycol, polyethylene glycol, sorbitol, glucose, maltitol, etc.

[0032] <Thickener> Pectin, carrageenan, galactomannan, xanthan gum, guar gum, tara gum, gum arabic, methylcellulose, hydroxyethylcellulose, gelatin, etc.

[0033] <Animal and plant extracts> Placenta extract, marine placenta extract, hydrolyzed collagen, hydrolyzed keratin, hydrolyzed silk, hydrolyzed elastin, yeast extract, aloe extract, comfrey extract, peony extract, perilla extract, swertia japonica extract, hamamelis water, sedge extract, hop extract, sage extract, horse chestnut extract, peach leaf extract, saxifrage extract, melissa extract, mugwort extract, rosemary extract, fermented rice bran extract, pine extract, prune extract, trehalose, sodium hyaluronate, fermented soybean extract, hydroxyethyl chitosan, water-soluble collagen, gynostemma pentaphyllum extract, fennel extract, pueraria root extract, kiwi extract, cucumber extract, gardenia extract, chlorella extract, rehmannia root extract, burdock root extract, loofah extract, peony extract, coltsfoot extract, poria cocos extract, grape leaf extract, coix seed extract, mugwort extract, apple extract , umbilical cord extract, hydrolyzed yeast extract, mucopolysaccharides, honey, hydrolyzed silk, aloe vera extract, peach leaf extract, St. John's wort extract, artemisia capillaris extract, raspberry extract, grapefruit extract, orchid extract, astragalus extract, atelocollagen, etc.

[0034] <Amino acids> Glycine, alanine, γ-aminobutyric acid, L-aspartic acid, L-arginine, L-isoleucine, L-glutamine, L-glutamic acid, L-threonine, L-tyrosine, L-tryptophan, L-valine, L-histidine hydrochloride, L-hydroxyproline, L-proline, L-leucine, L-methionine, lysine hydrochloride, etc.

[0035] <Wax> Shea butter, beeswax, carnauba wax, paraffin wax, microcrystalline wax, etc.

[0036] <Preservatives> Methylparaben, ethylparaben, propylparaben, butylparaben, isobutylparaben, phenoxyethanol, bisabolol, hinokitiol, benzoic acid, sodium benzoate, salicylic acid, sodium salicylate, sorbic acid, potassium sorbate, undecylenic acid, pionin, l-menthol, d-camphor, etc.

[0037] <Whitening agent> Ascorbic acid, ascorbic acid 2-glucoside, ethyl ascorbate, hydroquinone, arbutin, tretinoin, vitamin E, kojic acid, tranexamic acid, etc.

[0038] <UV absorber> Para-aminobenzoic acid, ethyl para-aminobenzoate, glyceryl para-aminobenzoate, 2-ethylhexyl para-dimethylaminobenzoate, oxybenzone, dihydroxybenzophenone, dihydroxydimethoxybenzophenone, sodium dihydroxydimethoxybenzophenone sulfonate, sodium hydroxymethoxybenzophenone sulfonate, octyl salicylate, etc.

[0039] <Sequestering agents> Edetic acid, edetate, trisodium ethylenediaminehydroxyethyltriacetate, diethylenetriaminepentaacetic acid, pentasodium diethylenetriaminepentaacetic acid, ethylenediaminetetrakis(2-hydroxyisopropyl) dioleate, hydroxyethanedisulfonic acid, tetrasodium hydroxyethanedisulfonate, phytic acid, etc.

[0040] <pH adjuster> Lactic acid, citric acid, glycolic acid, succinic acid, tartaric acid, malic acid and their salts, potassium carbonate, sodium hydrogen carbonate, ammonium hydrogen carbonate, potassium hydroxide, sodium hydroxide, monoethanolamine, triethanolamine, 2-amino-2-methylpropanediol, etc.

[0041] <Vitamins> Vitamin A, retinol acetate, pyridoxine hydrochloride, pyridoxine didecanoate, biotin, nicotinic acid, nicotinamide, benzyl nicotinate, riboflavin, calcium pantothenate, D-pantothenyl alcohol, ascorbic acid, ascorbyl palmitate, magnesium L-ascorbyl phosphate, ergocalciferol, vitamin E, tocopherol acetate, natural vitamin E, etc.

[0042] <Skin conditioning agent> Carboxyvinyl polymer, polyvinylpyrrolidone, cationized cellulose, cationized guar gum, sodium hyaluronate, sodium polyacrylate, hydrogenated polyisobutene, cetearyl alcohol, myristyl alcohol, hydrolyzed elastin, hydrolyzed keratin, hydrolyzed collagen, ethyl hydrolyzed collagen, hexadecyl hydrolyzed collagen, water-soluble collagen, xylitol, guanosine, guanine, glucuronic acid, sodium chondroitin sulfate, intercellular lipid, acidic mucopolysaccharide, water-soluble elastin, sphingolipid, sericin, soy lecithin lysophosphatidylcholine, soy phospholipid, tosaka extract, egg yolk phospholipid, hydrolyzed conchiolin, hydrolyzed eggshell membrane hydrolyzate, animal placenta extract, royal jelly extract, etc.

[0043] <Anti-inflammatory agent> Examples of antiperspirants include dipotassium glycyrrhizinate, allantoin, diphenhydramine hydrochloride, sodium guaiazulene sulfonate, benzyl nicotinate, lysozyme chloride, and aminocaproic acid.

[0044] As shown in the examples below, the topical skin preparation of the present invention can be used as a skin quality improving agent because it brings about a skin quality improving effect when applied to the skin. The amount of administration to the skin is not particularly limited, but it can be the amount applied when a topical skin preparation containing the amount of shikonin derivative described above is used in a normal manner. It is recommended to apply it to the skin daily, preferably for one week or more, more preferably for one month or more.

[0045] Furthermore, as shown in the examples below, the sunscreen of the present invention can be used as a sunscreen because it provides sunburn prevention effects when applied to the skin. The amount administered to the skin is not particularly limited, but may be the amount applied when a topical skin preparation containing the above-mentioned amount of shikonin derivative is used in a normal manner. The sunscreen can be applied evenly to cover the area of ​​the skin where sunburn is desired to be suppressed. Application to the skin can be done before exposure to the sun. [Example]

[0046] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0047] Example 1: Solution stability test of shikonin A 1 mM solution of shikonin was prepared by dissolving it in 1,3-butanediol at 40°C. 10 ml of this solution and 0.1 mmol of various additives were added to a 10 ml sealed brown glass container, and the container was left to stand in the dark at 50°C for one month. The amount of shikonin remaining after the standing time was measured using high-performance liquid chromatography (the remaining rate was evaluated as follows: less than 50% was marked x, 50-70% was marked △, 70-90% was marked ○, and 90% or more remaining was marked ◎). The results are shown in Table 1.

[0048] [Table 1]

[0049] The results in Table 1 show that hydrolyzable tannins are effective in stabilizing shikonin.

[0050] Example 2: Stability test of acylshikonin Instead of shikonin, an equal amount of acylshikonin (a mixture of acetylshikonin, isobutylshikonin, β,β-dimethylacrylshikonin, β-hydroxyisovalerylshikonin, isovalerylshikonin, etc.) was used, and the same test as in Example 1 was carried out. The results are shown in Table 2.

[0051] [Table 2]

[0052] The results in Table 2 show that hydrolyzable tannins are also effective in stabilizing acylshikonins.

[0053] Example 3: Photostability test of shikonin The shikonin solution of Example 1 was prepared. 10 ml of the solution and 0.1 mmol of various additives were added to a 10 ml transparent glass container with a seal, and the container was left to stand at room temperature in a bright room (south-facing windowsill) for 3 months. The amount of shikonin remaining after the lapse of time was measured using high-performance liquid chromatography (the remaining rate was evaluated as follows: less than 50% x, 50-70% △, 70-90% ○, and 90% or more remaining ⊚). The results are shown in Table 3.

[0054] [Table 3]

[0055] The results in Table 3 show that hydrolyzable tannins are also effective in stabilizing shikonin against light.

[0056] Example 4: Preparation of nanodispersion of shikonin 15 mg of shikonin was added to 3 ml of 1,3-butanediol and heated to 60°C for dissolution. Separately, 100 g of a 1% aqueous solution of Clariant's Aristoflex HMB (a crosspolymer of ammonium acryloyldimethyltaurate and beheneth-25 methacrylate) was prepared as a polymeric dispersant. This polymeric dispersant solution was placed in a homogenizer, and while vigorously stirring, a mixed solution of the shikonin solution and 3.0 g of argan oil was added at 40°C. Mixing was continued for 1 hour at 40°C to obtain a pale pink, transparent shikonin nanodispersion #1. This nanodispersion remained stable, with no precipitation or viscosity change of shikonin, even after aging at 40°C for 1 month.

[0057] Example 5 Shikonin nanodispersion #2 was prepared in the same manner as in Example 4, except that the polymeric dispersant Aristoflex HMB was replaced with Aristoflex AVC (a copolymer of ammonium acryloyldimethyltaurate and vinylpyrrolidone). This nanodispersion was stable for one month at 40°C.

[0058] Example 6 Shikonin nanodispersion #3 was prepared in the same manner as in Example 4, except that the polymer dispersant Aristoflex HMB was replaced with Seppic's SEPIPLUS 400 (a copolymer of sodium acryloyldimethyltaurate, acrylic acid, acrylic acid amide, and sodium acrylate). This nanodispersion was also stable at 40°C for one month.

[0059] Figure 1 shows photographs of shikonin nanodispersions #1, #2, and #3 prepared in Examples 4, 5, and 6.

[0060] Example 7 The polymer dispersant Aristoflex HMB in Example 4 was replaced with various low-molecular-weight dispersants and polymer dispersants, and argan oil was replaced with various solvents or the oil component of the present invention to examine the nano-dispersion of shikonin. The dispersibility of the resulting dispersions and their stability over a one-month period at 40°C were evaluated with a ○, △, or ×. The results are shown in Table 4.

[0061] [Table 4]

[0062] Table 4 shows that when the polymer dispersant of the present invention is used in combination with an oily component, a shikonin nanodispersion with excellent dispersibility and stability over time can be obtained.

[0063] Example 8: Preparation of a face cream A face cream containing shikonin was prepared according to the following formulation. 0.4g of sodium acryloyldimethyltaurate / hydroxyethyl acrylate copolymer was added to 80g of water at 40°C and stirred for 30 minutes. Next, 0.5g of taratannin, 5g of glycerin, 1.5g of sodium hyaluronate, 1g of raffinose, and 0.1g of allantoin were added at 40°C and stirred for 1 hour. Furthermore, a solution of 15mg of shikonin dissolved in a mixture of 1.5g of hexanediol, 0.5g of cetearyl glucoside, 8g of argan oil, 3g of cetearyl alcohol, 0.2g of orange oil, and 0.1g of patchouli oil was added at 65°C, heated and stirred for 1 hour, and then allowed to cool to room temperature to obtain a face cream.

[0064] The face cream was left to stand at 40°C for one month to evaluate its stability, but no abnormalities such as phase separation or crystal precipitation were observed.

[0065] Five women (aged 20-30) with rough skin were used as subjects. The face cream was applied daily for one month, and the sensory evaluation results are shown in Table 5 (5-point scale: 5 very good, 4 good, 3 average, 2 slightly bad, 1 bad).

[0066] [Table 5]

[0067] The results in Table 5 show that all subjects experienced an improvement in skin quality.

[0068] Example 9: Preparation of gel A face and body gel containing tara tannin was prepared according to the following formula: A 100g solution of 1% Aristoflex HMB in water was prepared. Next, 1.0g of taratannin and 0.1g of phenoxyethanol were added with stirring at 40°C. A solution of 15mg of shikonin dissolved in a mixture of 3.0g of 1,3-butanediol and 3.0g of argan oil was added at 50°C and mixed for 1 hour. The mixture was then allowed to cool, yielding a pale pink, transparent gel.

[0069] Six women in their 40s and 50s (one of whom served as a control) were selected as subjects. The gel was applied to the face, hands, and feet every day, and the degree of sunburn after outdoor exercise (tennis) was evaluated. The results of the sensory evaluation are shown in Table 6.

[0070] [Table 6]

[0071] The results in Table 6 show that all subjects felt the effects of sunscreen.

[0072] Example 10: Mask rash improvement test Five women in their 20s and 30s who had developed rough skin (mask rash) due to wearing masks for a long period of time were used as test subjects. The gel of Example 9 was applied twice a day, morning and night, for 10 days around the area where the mask came into contact with the skin, and the degree of improvement in the rash was evaluated by sensory evaluation. The results of the sensory evaluation are shown in Table 7.

[0073] [Table 7]

[0074] The results in Table 7 show that the mask rash was improved in all subjects.

Claims

1. A topical skin preparation containing an aqueous dispersion obtained by dispersing a shikonin derivative, a hydrolyzed tannin, and an oily component in a polymer dispersant having an acryloyldimethyltaurate salt as a monomer, the polymer dispersant is a polymer dispersant obtained by copolymerizing an acryloyldimethyltaurate salt with an acrylic acid derivative, a methacrylic acid derivative, or vinylpyrrolidone, The topical skin preparation, wherein the aqueous dispersion is a nanodispersion.

2. 2. The topical skin preparation according to claim 1, wherein said shikonin derivative is a shikonin derivative contained in the roots of Boraginaceae plants or an optical isomer thereof.

3. 2. The external skin preparation according to claim 1, wherein the hydrolyzable tannins are tara tannin, gallnut tannin (tannic acid), chestnut tannin, myraborum tannin, oak tannin and tea tannin.

4. A skin quality improving agent comprising the external skin preparation according to any one of claims 1 to 3.

5. A sunscreen comprising the external skin preparation according to any one of claims 1 to 3.

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