Aqueous composition and topical skin preparation

Abstract

An aqueous composition containing a vitamin E glycoside represented by general formula (1), 1,2-hexanediol, and water. In formula (1), R1, R2, and R3 each independently represent a hydrogen atom or a methyl group. Rx represents a monosaccharide. Ry represents a group represented by formula (Ry-1) or (Ry-2). * represents a bond to a carbon atom to which Ry in general formula (1) is bonded. The present invention also relates to an external preparation for skin containing the aqueous composition.

Description

[Technical field]

[0001] The present invention relates to an aqueous composition and an external preparation for skin. This application claims priority based on Japanese Patent Application No. 2022-206769, filed on December 23, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Patent Document 1 describes an antiallergic agent containing tocopheryl glycoside as an active ingredient, and lists tocopheryl glucoside as an example of the tocopheryl glycoside. Patent Document 2 discloses a delayed-type hypersensitivity preventive and therapeutic agent, an immunoglobulin E antibody production suppressant, and an anti-inflammatory agent, each of which contains tocopheryl glucoside as an active ingredient. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 61-030594 [Patent Document 2] International Publication No. 1991 / 007179 Summary of the Invention [Problem to be solved by the invention]

[0004] Glycosides of vitamin E (tocopherol or tocotrienol) have extremely low solubility in water, making it difficult to prepare them as aqueous compositions. Therefore, an object of the present invention is to provide an aqueous composition of a vitamin E glycoside and an external skin preparation containing said aqueous composition. [Means for solving the problem]

[0005] The present invention includes the following aspects. [1] An aqueous composition comprising a vitamin E glycoside represented by the following general formula (1), 1,2-hexanediol, and water:

[0006] [ka] [In the formula, R 1 , R 2 and R 3 each independently represents a hydrogen atom or a methyl group; Rx represents a monosaccharide; Ry represents a group represented by the following formula (Ry-1) or (Ry-2).

[0007] [ka] [In the formula, * represents a bond bonded to the carbon atom to which Ry in the general formula (1) is bonded.]

[0008] [2] The aqueous composition according to [1], comprising 0.01 to 2 mass % of the vitamin E glycoside and 0.5 to 20 mass % of the 1,2-hexanediol. [3] The aqueous composition according to [1] or [2], wherein the vitamin E glycoside is vitamin E glucoside. [4] The aqueous composition according to [1] or [2], wherein the vitamin E glycoside is tocopheryl glucoside. [5] A skin topical preparation comprising the aqueous composition according to any one of [1] to [4]. Effect of the Invention

[0009] According to the present invention, there are provided an aqueous composition of a vitamin E glycoside, and an external skin preparation containing said aqueous composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail, however, the present invention is not limited to the embodiments described below.

[0011] (Aqueous composition) In one embodiment, the present invention provides an aqueous composition comprising a vitamin E glycoside represented by the following general formula (1), 1,2-hexanediol, and water.

[0012] [ka] [In the formula, R 1 , R 2 and R 3 each independently represents a hydrogen atom or a methyl group; Rx represents a monosaccharide; Ry represents a group represented by the following formula (Ry-1) or (Ry-2).

[0013] [ka] [In the formula, * represents a bond bonded to the carbon atom to which Ry in the general formula (1) is bonded.]

[0014] <Vitamin E Glycoside> In this specification, a compound in which a monosaccharide is bound to vitamin E is referred to as vitamin E glycoside. Vitamin E is tocopherol and tocotrienol, and may be tocopherol alone, tocotrienol alone, or a mixture of both compounds. More specifically, vitamin E glycoside is a compound in which a monosaccharide is bound to tocopherol or tocotrienol. More specifically, it is a compound in which tocopherol or tocotrienol is bound to the carbon atom at the anomeric position (asymmetric carbon atom) of a monosaccharide. When Ry in the general formula (1) is a group represented by the formula (Ry-1), vitamin E glycoside is a compound in which tocopherol is bound to the carbon atom at the anomeric position of a monosaccharide (tocopheryl glycoside). When Ry in the general formula (1) is a group represented by the formula (Ry-2), the vitamin E glycoside is a compound (tocotrienyl glycoside) in which tocotrienol is bound to the anomeric carbon atom of a monosaccharide. The vitamin E glycoside may be a mixture of a compound in which tocopherol is bound to the anomeric carbon atom of a monosaccharide and a compound in which tocotrienol is bound to the anomeric carbon atom of a monosaccharide. Tocotrienols can be chemically unstable. In contrast, tocopherols are easily available as chemically synthesized products and are more chemically stable. For this reason, when vitamin E glycosides are used for skin external preparations and the like, it is preferable that the main component is tocopheryl glycoside or that the vitamin E glycosides are composed of tocopheryl glycosides.

[0015] Tocopherol is a compound represented by the following general formula (2): Tocotrienol is a compound represented by the following general formula (3):

[0016] [ka] [In the formula, R 1 , R 2 and R 3 each independently represents a hydrogen atom or a methyl group.

[0017] Tocopherols and tocotrienols include the R 1 , R 2 and R 3 α-tocopherol and α-tocotrienol (R 1 ,R 2 ,R 3 =CH3), β-tocopherol and β-tocotrienol (R 1 ,R 3 =CH3, R 2 =H), γ-tocopherol and γ-tocotrienol (R 1 =H, R 2 ,R 3 =CH3), δ-tocopherol and δ-tocotrienol (R 1 ,R 2 =H, R 3 =CH3) exists.

[0018] The tocopherol may be any of α-tocopherol, β-tocopherol, γ-tocopherol, and δ-tocopherol. The tocotrienol may be any of α-tocotrienol, β-tocotrienol, γ-tocotrienol, and δ-tocotrienol.

[0019] Tocopherol and tocotrienol each have an asymmetric carbon atom at the 2-position of the chroman ring, and therefore exist as d- and l-stereoisomers, as well as dl-stereoisomers. Tocopherol and tocotrienol may each be any of these stereoisomers. Tocopherol and tocotrienol each have their own characteristic physiological activities, but because their chemical properties are similar, a mixture of the two may be treated as vitamin E, or a small amount of tocotrienol may be contained in a product distributed as tocopherol. A small amount of tocopherol may also be contained in a product distributed as tocotrienol.

[0020] Rx in the general formula (1) represents a monosaccharide. More specifically, Rx is a monovalent group obtained by removing a hydroxyl group bonded to the carbon atom at the anomeric position from a monosaccharide. Examples of monosaccharides include glucose, mannose, galactose, fucose, rhamnose, and arabinose. The monosaccharide may be a D-form, an L-form, or a mixture thereof. The monosaccharide may be an α-form or a β-form. Glucose is preferable as the monosaccharide. A compound in which vitamin E and glucose are bonded together is called vitamin E glucoside. A compound in which tocopherol and glucose are bonded together is called tocopheryl glucoside. A compound in which tocotrienol and glucose are bonded together is called tocotrienyl glucoside.

[0021] As a specific example of vitamin E glucoside, a compound in which δ-tocopherol and β-D-glucose are bonded at the anomeric position is shown in the following formula (4). A compound in which δ-tocotrienol and β-D-glucose are bonded at the anomeric position is shown in the following formula (5).

[0022] [ka]

[0023] Vitamin E glycosides can be synthesized by reacting tocopherol or tocotrienol with a glycoside derivative by a known reaction. For example, as in the method described in JP 2008-133275 A, tocopherol or tocotrienol is reacted with peracetylated sugar in the presence of a suitable acid catalyst. Then, a derivative in which tocopherol or tocotrienol is bonded to the anomeric position of the peracetylated sugar is obtained. Then, the acetyl group is removed from this derivative by a deprotection reaction of the acetyl group, thereby synthesizing vitamin E glycosides. When the material used as vitamin E is a mixture of tocopherol and tocotrienol, a mixture of compounds having a structure derived from tocopherol and tocotrienol is obtained as vitamin E glycosides.

[0024] <1,2-Hexanediol> 1,2-Hexanediol may be of a grade that can be used as a cosmetic ingredient, such as that available from Kankosha Co., Ltd. under the trade name KMO-6.

[0025] <Water> The water used may be of a grade suitable for use in cosmetics, such as purified water.

[0026] <Aqueous composition> The term "aqueous composition" refers to a composition in which a solute is dissolved in a solvent mainly composed of water. In the aqueous composition of this embodiment, vitamin E glycoside is dissolved as a solute in a mixed solvent containing at least water and 1,2-hexanediol. In the aqueous composition, the proportion of water in the mixed solvent is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the total mass of the mixed solvent. The water content in the aqueous composition is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total mass of the aqueous composition. The water content in the aqueous composition is preferably 80 to 99.4% by mass, more preferably 90 to 99% by mass, and even more preferably 95 to 98% by mass, based on the total mass of the aqueous composition.

[0027] The content of vitamin E glycoside in the aqueous composition of this embodiment is preferably 0.01 to 2 mass% relative to the total mass of the aqueous composition, more preferably 0.1 to 1.0 mass%, and even more preferably 0.2 to 1.0 mass%.

[0028] The content of 1,2-hexanediol in the aqueous composition of the present embodiment is preferably 0.5 to 20 mass % relative to the total mass of the aqueous composition, more preferably 1 to 10 mass %, and even more preferably 2 to 5 mass %. In the aqueous composition of the present embodiment, when dissolving vitamin E glycosides utilizing the effect of 1,2-hexanediol, an organic solvent other than 1,2-hexanediol may be contained in the solvent. The organic solvent can be appropriately selected depending on the use of the aqueous composition. For example, when the organic solvent is a water-soluble alcohol such as ethanol, it is preferable to keep the content of the water-soluble alcohol to a level that does not impair the effect of 1,2-hexanediol, for example, 5% by mass or less (i.e., 0 to 5% by mass) based on the total mass of the aqueous composition.

[0029] When the contents of vitamin E glycoside and 1,2-hexanediol in the aqueous composition are within the above preferred ranges, the vitamin E glycoside dissolves sufficiently, and as a result, the physiological activity of the vitamin E glycoside can be fully exerted. In the aqueous composition, when the amount of 1,2-hexanediol is 20% by mass or less, the risk of problems such as irritation to the application site when applied as an external skin preparation is further reduced. Therefore, the content of 1,2-hexanediol in the aqueous composition is preferably 20% by mass or less.

[0030] The aqueous composition of this embodiment can be produced by dissolving vitamin E glycoside in a mixed solvent of water and 1,2-hexanediol. For example, the aqueous composition can be obtained by putting the mixed solvent of water and 1,2-hexanediol into a suitable container, adding vitamin E glycoside, and stirring to dissolve the vitamin E glycoside. The aqueous composition of this embodiment is usually a colorless and transparent liquid.

[0031] The present inventors measured the expression-promoting effect of the Transient receptor potential vanilloid 4 (TRPV4) gene using an aqueous composition containing tocopheryl glucoside as an example of the aqueous composition of this embodiment, and found that it has an excellent expression-promoting effect. TRPV4 is a protein discovered as an osmosensitive receptor activated by low osmolarity. TRPV4 functions as a water loss sensor, and it has been reported that activation by 4α-phorbol ester (4α-PDD) suppresses water loss and enhances skin barrier function. Tight junctions (TJs) are deeply involved in the skin barrier function. TJs are intercellular adhesion structures formed in a belt shape around epithelial cells. TJs bring adjacent epithelial cells into close contact with each other and seal the gaps, thereby preventing substances from entering or leaving through the gaps between cells. TJs are developed in the skin, trachea, intestinal tract, blood vessels, etc., and perform a barrier function to prevent fluids inside the tissue from passing through and to prevent foreign substances from entering from the outside. Claudins (CLDN) and occludin (OCL) are known as membrane proteins localized in TJs. There are 24 members of claudins, and claudin-1 (CLDN1) is responsible for strand formation in TJs and plays an important role in the formation of the intercellular barrier in the skin epidermis. It has been reported that activating TRPV4 present in the epidermis promotes the formation of TJs, improves the skin barrier function, and is effective in improving rough skin and moisturizing the skin. The aqueous composition of the present embodiment has the effect of promoting the expression of TRPV4 gene, CLDN1 gene, and OCL gene, and increasing the amount of TRPV4, OLDN1, and OCL. In addition, the aqueous composition of the present embodiment has the effect of suppressing the amount of transepidermal water loss. Therefore, the aqueous composition of the present embodiment can be used as an excellent skin roughness improving agent and / or skin moisturizing agent.

[0032] (External skin preparations) In one embodiment, the present invention provides an external preparation for skin. The external preparation for skin of this embodiment contains the aqueous composition.

[0033] When the aqueous composition of the present embodiment is used as an external preparation for skin, it may contain other components in addition to the aqueous composition. Examples of other components include pharma- ceutically acceptable carriers. As used herein, the term "pharmaceutical acceptable carrier" refers to a carrier that does not inhibit the physiological activity of an active ingredient and does not exhibit substantial toxicity to a subject to which it is administered. The term "not substantially toxic" means that the component is not toxic to a subject at a dose normally used. Examples of pharma- ceutically acceptable carriers include, but are not limited to, excipients, binders, disintegrants, lubricants, stabilizers, diluents, solvents for injections, moisturizers, texture enhancers, surfactants, polymers, thickeners, gelling agents, solvents, propellants, antioxidants, reducing agents, oxidizing agents, chelating agents, acids, alkalis, powders, inorganic salts, water, metal-containing compounds, unsaturated monomers, polyhydric alcohols, polymer additives, wetting agents, thickeners, tackifiers, oil-based raw materials, liquid matrices, fat-soluble substances, polymer carboxylates, and the like. In the barrier function-improving composition of the present embodiment, one type of pharma- ceutical acceptable carrier may be used alone, or two or more types may be used in combination.

[0034] Other ingredients include preservatives, antibacterial agents, UV absorbers, skin whitening agents, vitamins and their derivatives, anti-inflammatory agents, anti-inflammatory agents, hair growth agents, blood circulation promoters, stimulants, hormones, anti-wrinkle agents, anti-aging agents, tightening agents, cooling agents, warming agents, wound healing promoters, irritation relief agents, analgesics, cell activators, plant, animal, and microbial extracts, seed oils, antipruritics, keratin exfoliating and dissolving agents, antiperspirants, cooling agents, astringents, enzymes, nucleic acids, fragrances, dyes, colorants, dyes, pigments, anti-inflammatory and analgesic agents, antifungal agents, antihistamines, hypnotics and sedatives, tranquilizers, antihypertensive agents, antihypertensive diuretics, antibiotics, anesthetics, antibacterial substances, antiepileptic drugs, coronary vasodilators, herbal medicines, antipruritics, keratin softening and exfoliating agents, UV blocking agents, disinfectants, antioxidants, pH adjusters, additives, metal soaps, and the like. Specific examples of these components include those described in International Publication No. 2016 / 076310. These components may be used alone or in combination of two or more.

[0035] The topical skin preparation of the present embodiment can be produced by mixing the aqueous composition, and optionally a pharma- ceutically acceptable carrier and other ingredients, and formulating the mixture according to conventional methods (e.g., methods described in the Japanese Pharmacopoeia).

[0036] The skin topical preparation of the present embodiment may be a cosmetic product. Examples of types of cosmetic products include shampoo, conditioning shampoo, anti-dandruff shampoo, hair color shampoo, rinse-integrated shampoo, rinse, treatment, hair foam, hair mousse, hair spray, hair mist, hair gel, water grease, setting lotion, color lotion, hair tonic, hair liquid, hair blow, split end coat, permanent wave agent, straight perm agent, oxidation hair dye, hair bleach, hair color pre-treatment, and hair color after-treatment. hair cosmetics such as perm treatment, perm pre-treatment, perm after-treatment, hair manicure, hair growth agent; facial cleanser, cleansing foam, washing powder, facial cleansing powder, cleansing milk, cleansing lotion, cleansing gel, cleansing mask, lotion, softening lotion, astringent lotion, cleansing lotion, multi-layered lotion, milky lotion, emollient lotion, moisture lotion, milky lotion, nourishing lotion, nourishing milk, skin moisture, moisturizing emulsion , massage lotion, cleansing lotion, protective emulsion, sun protect, sun protector, UV care milk, sunscreen, makeup lotion, keratin smoother, elbow lotion, hand lotion, body lotion, cream, emollient cream, nutrition cream, nourishing cream, vanishing cream, moisture cream, night cream, massage cream, cleansing cream, makeup cream, base cream, pre-makeup cream, sunscreen cream, suntan cream, hair removal cream, deodorant cream, shaving cream, keratin softening cream, gel, cleansing gel, moisture gel, soap, cosmetic soap, transparent soap, medicated soap, liquid soap, shaving soap, synthetic cosmetic soap, pack, mask, peel-off pack, powder pack, washing pack, oil pack, cleansing mask, essence, moisturizing essence, whitening essence, UV protection essence, liposome beauty essence, liposome lotion and other basic cosmetics;Makeup cosmetics such as face powders, foundations, makeup bases, blushers, eyeliners, mascaras, eyeshadows, eyebrow pencils, nail enamel, enamel removers, and nail treatments; aromatic cosmetics such as perfumes, perfumes, eau de parfums, eau de toilettes, eau de colognes, perfume pastes, aromatic powders, perfumed soaps, body lotions, and bath oils; body cosmetics such as body shampoos, body washes, body powders, deodorant lotions, deodorant powders, deodorant sprays, deodorant sticks, deodorant cosmetics, bleaching agents, depilatories, bath agents, insect repellent sprays, and insect repellers; ointments, patches, lotions, liniments, and liquid coating agents.

[0037] (Other embodiments) In one embodiment, the present invention provides a method for moisturizing skin, improving dry skin, or improving rough skin, comprising the step of applying the aqueous composition to the skin of a subject. In one embodiment, the present invention provides a method of promoting the production of TRPV4, CLDN1, and OCL1, comprising applying the aqueous composition to the skin of a subject. In one embodiment, the present invention provides the aqueous composition for moisturizing skin, improving dry skin, or improving rough skin. In one embodiment, the present invention provides said aqueous-based composition for promoting the production of TRPV4, CLDN1, and OCL1. In one embodiment, the present invention provides use of the aqueous composition for producing an external skin preparation for moisturizing skin, improving dry skin, or improving rough skin. In one embodiment, the present invention provides use of the aqueous composition for manufacturing an agent for promoting the production of TRPV4, CLDN1, and OCL1. In one embodiment, the present invention provides use of the aqueous composition for moisturizing skin, improving dry skin, or improving rough skin. In one embodiment, the present invention provides a use of the aqueous composition for promoting the production of TRPV4, CLDN1, and OCL1. EXAMPLES

[0038] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0039] The D-δ-tocopheryl glucoside used in the following experiments was synthesized with reference to the synthesis method described in JP-A-2008-133275 and the like.

[0040] [Experimental Example 1] (Confirmation of solubility of tocopheryl glucoside) The solubility of D-δ-tocopheryl glucoside (hereinafter sometimes abbreviated as "δ-TPG") was investigated. As shown in Tables 1 and 2, water and 1,2-hexanediol (hereinafter sometimes abbreviated as "HD") or ethanol (hereinafter sometimes abbreviated as "EtOH") were mixed to prepare mixtures for each example. 9.9 g of each mixture was placed in each vial, and 0.01 g of solid δ-TPG was added to each vial and stirred at room temperature. After stirring for 1 hour, the state of each vial was observed. The solubility of δ-TPG was evaluated from the observation results of the vials based on the following evaluation criteria. The results are shown in Tables 1 and 2 as "Solubility Evaluation". <Evaluation criteria> A: It completely dissolved and became clear. B: Precipitation or cloudiness occurred.

[0041] Table 1 shows the results of dissolving 0.01 g of δ-TPG in each mixture of water and HD (Examples 1 to 4). Table 2 shows the results of dissolving 0.01 g of δ-TPG in each mixture of water and EtOH (Comparative Examples 1 and 2).

[0042] [Table 1]

[0043] [Table 2]

[0044] δ-TPG did not dissolve in water. However, it was completely dissolved in EtOH or HD. Using EtOH or HD at high concentrations is not preferable for aqueous compositions. Therefore, the solubility of δ-TPG in aqueous compositions containing a reduced amount of these compounds, i.e., low concentrations of EtOH or HD, was examined. In the case of mixtures containing 5% by mass or 10% by mass of EtOH, δ-TPG did not dissolve (Table 2). In contrast, when the mixture was prepared using HD, δ-TPG dissolved even in a mixture with a low HD concentration of about 0.5% by mass, and a clear aqueous composition was obtained (Table 1).

[0045] [Experimental Example 2] (Confirmation of activity of aqueous composition containing δ-TPG and HD: Expression of TRPV4 gene) Normal human epidermal keratinocytes (NHEK, Kuraray Industries, Inc.) were cultured at 10,000 cells / cm 2 The cells were seeded at a seeding density of 1000×1000 on a plastic petri dish and cultured for 24 hours in a serum-free growth medium for normal human epidermal keratinocytes (Kuraray Industries, Inc.). 8.94 g of water, 1.0 g of HD, and 0.06 g of δ-TPG were mixed and stirred to obtain an aqueous composition. The aqueous composition was added to the culture medium in which the above-mentioned NHEK cells were cultured for 24 hours so that the final concentration of δ-TPG was 10 μM. After the addition of δ-TPG, the culture was further cultured for 48 hours. Then, the culture was irradiated with 60 mJ / cm 2 UVB radiation using a UVP UVB irradiation device. 2 After that, fresh normal human epidermal keratinocyte proliferation medium was added to the culture solution, and the cells were further cultured for 24 hours. In this way, the cells for evaluation were obtained.

[0046] Total RNA was extracted from the cells for evaluation obtained above, and cDNA was synthesized. Next, quantitative real-time PCR was performed using the above cDNA as a template to quantify the expression level of the TRPV4 gene in NHEK cells. The expression level of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was quantified as an internal standard gene. GAPDH is a housekeeping gene whose expression does not change with the addition of compounds. The expression level of the TRPV4 gene was standardized based on the expression level of the GAPDH gene in NHEK cells. Primer GAPDH (ID: HA067812) manufactured by Takara Bio was used as a primer for amplifying the GAPDH gene. Primer TRPV4 (ID: HA186338) manufactured by Takara Bio was used as a primer for amplifying the TRPV4 gene.

[0047] Instead of δ-TPG, D-α-tocopheryl glucoside (hereinafter sometimes abbreviated as "α-TPG"), tocopherol acetate (Fujifilm Wako Pure Chemical Industries, Ltd.; hereinafter sometimes abbreviated as "TPA"), δ-tocopherol (Sigma-Aldrich; hereinafter sometimes abbreviated as "δ-TP"), or α-tocopherol (Junsei Chemical Co., Ltd.; hereinafter sometimes abbreviated as "α-TP") was used to obtain evaluation cells by the same procedure as above. The expression level of the TRPV4 gene was measured for these evaluation cells by the same procedure as above.

[0048] The expression level of TRPV4 gene was calculated as a relative value when the expression level of TRPV4 gene in the control cells was set to 1. The control cells were prepared by culturing NHEK cells without adding the test compound to the cell culture medium and without irradiating UVB. HD was added to the cell culture medium of the control cells so that the HD concentration in the cell culture medium was the same as that in the cell culture medium when the δ-TPG was added and cultured. The culture conditions of NHEK cells were the same as those when the δ-TPG was added, except that the δ-TPG was not added and the UVB irradiation was not performed.

[0049] The comparative cells were prepared by culturing NHEK cells without adding the test compound to the cell culture medium and irradiating UVB. HD was added to the cell culture medium of the comparative cells, so that the HD concentration in the cell culture medium was the same as that in the cell culture medium when the δ-TPG was added and cultured. The culture conditions of the comparative cells were the same as those in the case of adding the δ-TPG, except that the δ-TPG was not added. The expression level of the TRPV4 gene in the comparative cells was determined by the same method as above. An aqueous composition containing tocopheryl glucoside but not HD was also prepared, but tocopheryl glucoside was not sufficiently dissolved in the aqueous composition, and therefore the preparation of evaluation cells and the measurement of the expression level of the TRPV4 gene were not performed.

[0050] The results are shown in Table 3.

[0051] [Table 3]

[0052] By irradiating with UVB, the expression of TRPV4 gene was decreased. On the other hand, by adding an aqueous composition containing tocopheryl glucoside (δ-TPG, α-TPG) to the culture solution, the decrease in the expression of TRPV4 caused by UVB irradiation was significantly suppressed. This result shows that tocopheryl glucoside has an effect of significantly promoting the expression of TRPV4 gene in cells irradiated with UVB. The expression promoting effect of TRPV4 gene by tocopheryl glucoside was significantly higher than that by δ-TP, α-TP, and TPA.

[0053] [Experimental Example 3] (Confirmation of activity of aqueous compositions of δ-TPG and HD: Effect of promoting expression of TJ-related genes) Normal human epidermal keratinocytes (NHEK, Kurabo Industries, Ltd.) were subjected to the same procedure as in Experimental Example 2 to obtain cells for evaluation. Total RNA was extracted from the thus obtained cells for evaluation, and cDNA was synthesized. Next, quantitative real-time PCR was performed using the above cDNA as a template to quantify the expression levels of the claudin 1 (CLDN1) gene and occludin (OCL) gene in the NHEK cells. In addition, the expression level of GAPDH was quantified as an internal standard gene. The expression levels of the CLDN1 gene and the OCL gene were standardized based on the expression level of the GAPDH gene in the NHEK cells. As a primer for amplifying the GAPDH gene, a primer GAPDH (ID: HA067812) manufactured by Takara Bio Inc. was used. As a primer for amplifying the CLDN1 gene, a primer CLDN1 (ID: HA103348) manufactured by Takara Bio Inc. was used. As a primer for amplifying the OCL gene, a primer OCL (ID: HA036753) manufactured by Takara Bio Inc. was used.

[0054] The same procedure as above was carried out using α-TPG, TPA, δ-TP, or α-TP instead of δ-TPG to obtain evaluation cells. The expression levels of the CLDN1 gene and the OCL gene were measured for these evaluation cells by the same procedure as above.

[0055] The expression level of each gene was determined as a relative value when the expression level of each gene in the control cells was set to 1. The control cells were prepared by the same procedure as for the control cells in Experimental Example 2.

[0056] The expression levels of the CLDN1 gene and the OCL gene in the comparative cells were determined by the same method as described above. The comparative cells were prepared by the same procedure as the comparative cells in Experimental Example 2. An aqueous composition containing tocopheryl glucoside but not HD was also prepared, but tocopheryl glucoside was not sufficiently dissolved in the aqueous composition, and therefore the preparation of cells for evaluation and the measurement of the expression levels of the CLDN1 gene and the OCL gene were not performed.

[0057] The results are shown in Table 4.

[0058] [Table 4]

[0059] UVB irradiation reduced the expression of the CLDN1 gene and the OCL gene (comparison between "no UVB irradiation, added sample -" and "UVB irradiation, added sample -"). On the other hand, the expression levels of the CLDN1 gene and the OCL gene were significantly increased by adding an aqueous composition containing tocopheryl glucoside (δ-TPG, α-TPG) to the culture medium. The effect of tocopheryl glucoside in promoting the expression of the CLDN1 gene and the OCL gene was significantly higher than the effect of δ-TP, α-TP, and TPA in promoting the expression of the CLDN1 gene and the OCL gene.

[0060] [Experimental Example 4] (TJ formation ability evaluation test) A skin model (model "EP1-200", manufactured by Kurabo Industries, Ltd.) was pre-cultured for 1 hour under conditions of 37°C and 5% CO2. Next, δ-TPG dissolved at a concentration of 0.2% by mass in a 0.5% by mass HD aqueous solution was added to the surface of the skin model, and the model was further cultured for 24 hours. Next, δ-TPG was removed, and the model was washed three times with phosphate buffer, after which the transepidermal water loss (TEWL) was measured. A cyclone water loss meter (manufactured by Nippon Ash Co., Ltd.) was used to measure TEWL.

[0061] The same procedure as above was carried out using TPA instead of δ-TPG to measure TEWL.

[0062] As a control, the same procedure as above was carried out using a 0.5% by mass HD aqueous solution containing no δ-TPG instead of the 0.5% by mass HD aqueous solution, and the TEWL was measured.

[0063] The same procedure as above was carried out using δ-TP dissolved at a concentration of 0.2% by mass in 1% by mass HD instead of δ-TPG dissolved in 0.5% by mass HD, and TEWL was measured.

[0064] The TEWL measurement results are shown in Table 5. It was confirmed that TEWL was suppressed in the group to which δ-TPG was added. This result indicates that δ-TPG promotes TJ formation, thereby enhancing the skin's moisturizing ability (moisture retention function).

[0065] [Table 5]

[0066] After the TEWL measurement, each skin model was collected and embedded in paraffin, and tissue slice specimens were prepared using a sectioning device. The tissue section specimen was deparaffinized and dehydrated to obtain a skin tissue sample. The skin tissue sample was subjected to immunostaining. Rabbit anti-TRPV4 antibody, rabbit anti-occludin antibody, or rabbit anti-claudin 1 antibody (all manufactured by Abcam) was used as the primary antibody. Each antibody was diluted with phosphate buffer containing 0.05% by mass of Tween-20 at the dilution ratio of rabbit anti-TRPV4 antibody (1:100), rabbit anti-occludin antibody (1:100), or rabbit anti-claudin 1 antibody (1:100). As the secondary antibody, horseradish peroxidase-conjugated donkey anti-rabbit IgG antibody (manufactured by Abcam) was used after dilution at 1:1000 with phosphate buffer containing 0.05% by mass of Tween-20. After reaction with the primary and secondary antibodies, the skin tissue sample was washed. Thereafter, a color reaction was carried out using the peroxidase color-developing substrate 3,3'-diaminobenzidine tetrahydrochloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Each skin tissue sample was observed and photographed under an inverted microscope (Nikon TS1). Three independent images were obtained, and quantitative analysis of the brightness values ​​correlated with the protein expression levels was performed using Image J software (NIH).

[0067] The results are shown in Table 6. The brightness value of each gene in each example is shown as a relative value when the average brightness value of each gene in skin tissue samples using a 0.5% by mass HD aqueous solution containing no test compound was set to 1.00.

[0068] [Table 6]

[0069] In the group to which tocopheryl glucoside (δ-TPG, α-TPG) was added, the protein levels of TRPV4, CLDN1, and OCL1 were confirmed to increase. These results indicate that tocopheryl glucoside increases the protein level of TRPV4, thereby suppressing water loss from the skin. They also indicate that tocopheryl glucoside increases the protein levels of CLDN1 and OCL1, thereby promoting TJ formation, and thus enhancing the skin's moisturizing ability.

[0070] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the attached claims.

Claims

1. The present invention relates to a composition comprising a vitamin E glycoside represented by the following general formula (1), 1,2-hexanediol, and water, The composition contains 0.01 to 2% by mass of the vitamin E glycoside and 0.5 to 20% by mass of the 1,2-hexanediol, An aqueous composition, wherein the vitamin E glycoside is tocopheryl glucoside. 【Chemistry 1】 [In the formula, R １ , R ２ and R ３ each independently represents a hydrogen atom or a methyl group; Rx represents a monosaccharide; and Ry represents a group represented by the following formula (Ry-1). 【Chemistry 2】 [In the formula, * represents a bond bonded to the carbon atom to which Ry in the general formula (1) is bonded.]

2. A skin external preparation comprising the aqueous composition according to claim 1.

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