Cosmetic composition

Abstract

The purpose of the present invention is to provide a cosmetic composition that allows a compound having an amide bond or an amino group, such as an amino acid, to penetrate into the corneum, the cosmetic composition exhibiting excellent stability and being unlikely to undergo gelling in particular. This cosmetic composition contains sodium dilauramidoglutamide lysine, a compound having an amide bond or an amino group, and water. The sodium dilauramidoglutamide lysine and the compound having an amide bond or an amino group are dissolved in water. The pH of the composition at 25°C is 6.3 or more.

Description

Cosmetic composition

[0001] The present invention relates to a cosmetic composition, and to a cosmetic composition containing a compound having an amide bond or an amino group.

[0002] As the outermost layer of the body, skin is constantly exposed to external stimuli. The epidermis is a very thin membrane, averaging approximately 0.2 mm thick. Located at the outermost layer of the skin, it acts as a barrier to prevent the intrusion of foreign substances and evaporation of body moisture, protecting the interior. The epidermis is composed of four layers: the stratum corneum, stratum granulosum, stratum spinosum, and stratum basale. The stratum corneum is located at the outermost surface of the epidermis, averaging approximately 0.02 mm thick and composed of approximately 10 to 20 layers of keratinocytes sandwiched between intercellular lipids. Although the stratum corneum is an extremely thin membrane, it fulfills the important roles of barrier and moisturizing. The barrier function has two functions: it prevents external stimuli such as dust and bacteria from entering the body from the skin surface, and it prevents excessive evaporation of body moisture, preventing the body from becoming dry. Its moisturizing function also keeps the stratum corneum moist.

[0003] Amino acids are functional ingredients widely used in foods, cosmetics, and pharmaceuticals. Amino acids are generally found in large amounts in the human body as protein components, but free amino acids are abundant in the stratum corneum, the outermost layer of the skin, where they act as natural moisturizing components and contribute to skin hydration.

[0004] NMF (natural moisturizing factor) is a natural moisturizer produced by skin in keratinocytes. NMF binds very easily to water molecules, and once bound to water, it becomes water that is very difficult to evaporate.

[0005] NMF is composed of 40% free amino acids, 12% pyrrolidone carboxylic acid (PCA), 12% lactate, 7% urea, 19% minerals, and 10% others, with more than half being made up of free amino acids and amino acid-derived components such as PCA. Furthermore, the free amino acid components are composed of 30% serine, 18% glycine, 9% alanine, 7% threonine, 5% aspartic acid, and 31% others.

[0006] Therefore, in order to provide a cosmetic product that has the function of enhancing the inherent beauty of skin, such as making skin lustrous and moisturized, a cosmetic product is required in which amino acids such as NMF penetrate into the stratum corneum and / or are normally retained in the stratum corneum. However, amino acids such as NMF are generally water-soluble, and therefore have low permeability into the stratum corneum, which is the outermost layer of the skin and has lipid-soluble properties. Furthermore, amino acids such as NMF in the stratum corneum are easily washed away by daily washing, etc., and even if they are simply given externally for the purpose of replenishment, it is difficult to retain them in the surface layer.

[0007] A topical composition containing an amino acid and sodium dilauramidoglutamide lysine, which enhances the transdermal absorbability of the amino acid, has been reported (Patent Document 1). Sodium dilauramidoglutamide lysine is a highly functional ingredient made from natural fatty acids and the amino acids glutamic acid and lysine, which act to organize disordered structures, support barrier function, and increase water retention.

[0008] However, the compositions described in the above documents tend to gel easily, and therefore there is room for improvement in terms of stability. Furthermore, in the compositions described in the above documents, the amino acids permeate the stratum corneum and skin and are absorbed into a receiver solution intended for the deep skin and the whole body, but no consideration has been given to their retention in the stratum corneum.

[0009] JP 2016-33161 A

[0010] The present invention has been made in view of the above circumstances, and aims to provide a cosmetic composition that allows a compound having an amide bond or an amino group, such as an amino acid, to penetrate into the stratum corneum, and that has excellent stability, particularly a cosmetic composition that is resistant to gelation.

[0011] The present inventors have discovered that by adjusting a cosmetic composition in which sodium dilauramidoglutamide lysine (DLGL) and a compound having an amide bond or an amino group are dissolved in water to a specific pH range, the stability of such a cosmetic composition can be improved, and more specifically, gelation of such a cosmetic composition can be suppressed.

[0012] Furthermore, the present inventors have found that when sodium dilauroyl glutamate lysine (DLGL) is used with a compound having an amide bond or an amino group, particularly a moisturizing compound having a specific structure, it can retain the compound in the stratum corneum. Further research has revealed that this stratum corneum retention effect is due to the intermolecular interaction between sodium dilauroyl glutamate lysine (DLGL) and the target compound. Furthermore, the present inventors have found that sodium dilauroyl glutamate lysine (DLGL) retains moisturizing compounds in the stratum corneum for a long period of time, thereby smoothing the surface of keratinocytes. These are surprising effects newly obtained by the present invention.

[0013] Therefore, the present invention relates to the following inventions: <Aspect 1> A cosmetic composition comprising sodium dilauramidoglutamide lysine, a compound having an amide bond or an amino group, and water, wherein the sodium dilauramidoglutamide lysine and the compound having an amide bond or an amino group are dissolved in the water, and wherein the pH value at 25°C is 6.3 or higher. <Aspect 2> The cosmetic composition according to Aspect 1, further comprising a water-soluble polyether-modified silicone and / or a water-soluble polyether-modified silane. <Aspect 3> The cosmetic composition according to Aspect 2, wherein the water-soluble polyether-modified silicone comprises PEG-10 methyl ether dimethicone and / or PEG / PPG-30 / 10 dimethicone. <Aspect 4> The cosmetic composition according to Aspect 2, wherein the water-soluble polyether-modified silane comprises bisPEG-18 methyl ether dimethyl silane. Aspect 5: The cosmetic composition according to any one of Aspects 2 to 4, wherein the water-soluble polyether-modified silicone or the water-soluble polyether-modified silane is present in an amount of 20 to 300 parts by mass per 100 parts by mass of the total of the compound having an amide bond or an amino group and the sodium dilauroyl glutamate lysine. Aspect 6: The cosmetic composition according to any one of Aspects 1 to 5, wherein the compound having an amide bond or an amino group is a natural moisturizing factor (NMF). Aspect 7: The cosmetic composition according to any one of Aspects 1 to 5, wherein the compound having an amide bond or an amino group comprises at least one selected from the group consisting of asparagine, lysine, pyrrolidonecarboxylic acid and salts thereof, and uridine. Aspect 8: The cosmetic composition according to any one of Aspects 1 to 7, wherein the mass ratio of the sodium dilauroyl glutamate lysine to the compound having an amide bond or an amino group (sodium dilauroyl glutamate lysine / compound having an amide bond or an amino group) is 0.01 or greater. Aspect 9: The cosmetic composition according to any one of Aspects 1 to 8, wherein the mass ratio of the sodium dilauroyl glutamate lysine to the compound having an amide bond or an amino group (sodium dilauroyl glutamate lysine / compound having an amide bond or an amino group) is 1.0 or less.Aspect 10: The cosmetic composition according to any one of Aspects 1 to 9, which is used in skin care compositions including lotions, emulsions, serums, and creams.

[0014] The cosmetic composition of the present invention, in which sodium dilauramidoglutamide lysine and a compound having an amide bond or an amino group are dissolved in water, has a pH value within a specific range, thereby providing the effect of allowing the compound having an amide bond or an amino group to penetrate into the stratum corneum while maintaining high stability, particularly inhibiting gelation.

[0015] Furthermore, according to the cosmetic composition of the present invention, a compound having an amide bond or an amino group, particularly a specific moisturizing compound, can be retained in the stratum corneum using sodium dilauramidoglutamide lysine, and a composition containing both compounds is effective as a moisturizing agent that enhances skin moisture. Furthermore, this retention effect smoothes the surface of keratinocytes, making the composition particularly effective as a gloss-improving agent that enhances the natural beauty of skin, adding smoothness and luster.

[0016] Figure 1 shows the stratum corneum permeability of sodium pyrrolidonecarboxylate (PCA-Na) 24 hours after application. The results are shown for unapplied, PCA-Na alone (PCA), and combined application of PCA-Na and DLGL (PCA-DLGL). With combined application of PCA and DLGL, the PCA concentration was high in the shallow layer where leakage is likely, confirming that DLGL is effective in retaining PCA-Na in the stratum corneum. Figure 2 shows the stratum corneum permeability of proline 24 hours after application. The results are shown for unapplied, proline alone, and combined application of proline and DLGL. No significant difference in the amount of stratum corneum permeation after 24 hours was observed with the combination of L(-)proline and DLGL. Figure 3 shows the results of measuring the surface roughness of keratinocytes after application of PCA-Na alone, DLGL alone, and PCA-Na and DLGL (PCA-DLGL). It was confirmed that the use of both PCA and DLGL improved the roughness of the keratinocyte surface and smoothed the surface. Figure 4 shows the results of measuring the moisture content of the stratum corneum using a SKICON device. The combined application of PCA-Na and DLGL maintained a higher SKICON value even after 24 hours compared to the unapplied application or PCA-Na alone, confirming that moisture content was maintained in the shallow surface layers. Figure 5 shows the amount of PCA in the stratum corneum after immersion in water, PCA-Na alone (PCA), and PCA-Na and DLGL (PCA-DLGL). It was confirmed that PCA penetrates into the stratum corneum by using PCA-Na in combination with DLGL. Figure 6 shows the surface roughness (Ra) of stratum corneum cells after immersion in water, PCA-Na alone (PCA), PCA-Na and DLGL (PCA-DLGL), and drying of the collected stratum corneum. It was confirmed that the surface roughness was reduced by immersion in PCA-Na, and that the surface roughness was further reduced by using PCA-Na in combination with DLGL.

[0017] Cosmetic Composition In one aspect of the present invention, the present invention relates to a cosmetic composition comprising sodium dilauramidoglutamide lysine, a compound having an amide bond or an amino group, and water, wherein the sodium dilauramidoglutamide lysine and the compound having an amide bond or an amino group are dissolved in the water, and the cosmetic composition has a pH value at 25°C of 6.3 or higher.

[0018] The cosmetic composition of the present invention, in which sodium dilauramidoglutamide lysine and a compound having an amide bond or an amino group are dissolved in water, has a pH value within a specific range, thereby providing the effect of allowing the compound having an amide bond or an amino group to penetrate into the stratum corneum while maintaining high stability, particularly inhibiting gelation.

[0019] Here, the cosmetic composition of the present invention may have a pH value at 25° C. of 6.3 or more, 6.4 or more, 6.5 or more, 6.7 or more, 7.0 or more, 7.1 or more, 7.2 or more, 7.3 or more, 7.4 or more, or 7.5 or more. Also, this pH value may be 8.0 or less, 7.8 or less, 7.5 or less, 7.0 or less, 6.9 or less, 6.8 or less, 6.7 or less, 6.6 or less, or 6.5 or less.

[0020] Furthermore, according to the cosmetic composition of the present invention, a compound having an amide bond or an amino group, particularly a specific moisturizing compound, can be retained in the stratum corneum using sodium dilauramidoglutamide lysine, and a composition containing both compounds is effective as a moisturizing agent that enhances skin moisture. Therefore, the cosmetic composition of the present invention may be a cosmetic composition for retention in the stratum corneum, which retains a compound having an amide bond or an amino group in the stratum corneum. Furthermore, this retention effect smoothes the surface of keratinocytes, and such a composition is particularly effective as a gloss-improving agent that enhances the natural beauty of smooth, lustrous skin.

[0021] In this specification, "stratum corneum retention" means that the target moisturizing factor, such as an amino acid, has sufficiently penetrated into the stratum corneum (preferably the surface layer), and even after application, at least a portion of the target moisturizing factor does not flow out of the stratum corneum and disappear, but remains in the stratum corneum. Therefore, "retention in the stratum corneum" is completely different from the penetration or absorption of the target compound through the stratum corneum.

[0022] Such stratum corneum retention effect can be confirmed by measuring the concentration of the target compound in the stratum corneum and the amount of moisture on the surface when the stratum corneum retention promoter is applied together with the target moisturizing compound using a SKICON device or the like.

[0023] The cosmetic composition of the present invention is particularly effective in retaining compounds having an amide bond or an amino group, which tend to leak from the stratum corneum surface, particularly moisturizing compounds, in the stratum corneum for a long period of time. This effect is due to the formation of an intermolecular bond between sodium dilauroyl glutamate lysine and the compound having an amide bond or an amino group, resulting in a steric interaction.

[0024] In the present invention, a natural moisturizing factor (NMF) can be used as the compound having an amide bond or an amino group.

[0025] Specific examples of compounds having an amide bond or an amino group include compounds such as urea, hydroxyurea, hydroxyethylimidazolidinone, uridine, and guanine, various amino acids such as glutamine, asparagine, and lysine, amino acid-derived pyrrolidone carboxylic acid (PCA), and glycylglycine. Asparagine, lysine, and pyrrolidone carboxylic acid, known as NMFs, are most preferred, and among NMFs, asparagine or lysine, which are amino acids or amino acid-derived compounds having an amide bond or an amino group in the side chain, are most preferred.

[0026] In the present invention, the compound having an amide bond or an amino group may be at least one selected from the group consisting of asparagine, lysine, pyrrolidonecarboxylic acid and salts thereof, and uridine.

[0027] Furthermore, the salt of pyrrolidonecarboxylic acid is not particularly limited, and examples thereof include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; organic base salts such as zinc salt, ethanolamine salt and diethanolamine salt; and basic amino acid salts such as lysine salt and arginine salt. Of these, alkali metal salts such as sodium salt and potassium salt are preferred, and sodium salt is most preferred.

[0028] In the cosmetic composition of the present invention, the mass ratio of sodium dilauroyl glutamate lysine to the compound having an amide bond or an amino group (sodium dilauroyl glutamate lysine / compound having an amide bond or an amino group) is, for example, 0.01 or more, 0.05 or more, 0.1 or more, or 0.2 or more.

[0029] In addition, in the cosmetic composition of the present invention, the mass ratio of sodium dilauroyl glutamate lysine to the compound having an amide bond or an amino group (sodium dilauroyl glutamate lysine / compound having an amide bond or an amino group) is, for example, 1.0 or less, 0.8 or less, or 0.6 or less.

[0030] The cosmetic composition of the present invention contains sodium dilauroyl glutamate lysine and a compound having an amide group or an amino group, and the interaction between the two substances promotes the retention of the target compound in the stratum corneum. Therefore, the stratum corneum retention composition of the present invention can be effectively used as a moisturizing agent that increases skin moisture. Furthermore, the interaction between the two compounds makes it possible to smooth the surface of keratinocytes, imparting smoothness and luster to the skin. Therefore, the cosmetic composition of the present invention can be effectively used as a stratum corneum smoothing agent or luster improving agent.

[0031] In the cosmetic composition of the present invention, particularly in the cosmetic composition of the present invention used as a stratum corneum reservoir composition, a skin topical preparation, a moisturizer, and a gloss improver, the blending amount of sodium dilauroyl glutamate lysine is, for example, preferably 0.0001 to 10 wt %, and more preferably 0.005 to 5 wt %, of the total amount of the cosmetic composition.

[0032] Furthermore, in the cosmetic composition of the present invention, particularly in the cosmetic composition of the present invention used as a stratum corneum storage composition, a topical skin preparation, a moisturizer, and a gloss improver, the amount of the compound having an amide bond or an amino group may be, for example, 0.001 wt % or more, 0.005 wt % or more, 0.01 wt % or more, or 0.05 wt % or more, and may be 10 wt % or less, 5 wt % or less, 3 wt % or less, 1 wt % or less, or 0.5 wt % or less, based on the total amount of the topical preparation (composition).

[0033] (Water-soluble polyether-modified silicone and / or water-soluble polyether-modified silane) The cosmetic composition of the present invention may further comprise a water-soluble polyether-modified silicone and / or a water-soluble polyether-modified silane. Here, the water-soluble polyether-modified silicone may comprise PEG-10 methyl ether dimethicone and / or PEG / PPG-30 / 10 dimethicone. Furthermore, the water-soluble polyether-modified silane may comprise bisPEG-18 methyl ether dimethyl silane.

[0034] When the cosmetic composition of the present invention further comprises a water-soluble polyether-modified silicone and / or a water-soluble polyether-modified silane, the cosmetic composition of the present invention has improved usability, and in particular, the stickiness of the cosmetic composition of the present invention can be suppressed.

[0035] In the present invention, "water-soluble" means that when mixed with water at room temperature (25°C) at a concentration of 1% by mass, a solution that is transparent and has a single-phase appearance is produced, and in particular, when mixed with water at room temperature (25°C) at the concentration used in the cosmetic composition of the present invention, a solution that is transparent and has a single-phase appearance is produced.

[0036] Here, the amount of the water-soluble polyether-modified silicone or water-soluble polyether-modified silane may be 20 to 300 parts by weight per 100 parts by weight of the total of the compound having an amide bond or an amino group and sodium dilauramidoglutamate lysine. This amount may be, for example, 20 parts by weight or more, more than 20 parts by weight, 30 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, or 100 parts by weight or more, and may be 300 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, 180 parts by weight or less, 170 parts by weight or less, 160 parts by weight or less, 150 parts by weight or less, or 140 parts by weight or less. When this amount is within the above range, good usability can be achieved and appropriate moisturizing power can be provided. Furthermore, when the cosmetic composition of the present invention contains both a water-soluble polyether-modified silicone and a water-soluble polyether-modified silane, the total content thereof may be within the above range.

[0037] (Other Components) In addition to the above-mentioned components, the cosmetic composition of the present invention may further contain, as necessary, components typically used in external skin preparations such as cosmetics and pharmaceuticals, such as antioxidants, oils, UV protection agents, surfactants, thickeners, alcohols, powder components, colorants, aqueous components, water, various skin nutrients, etc., within the scope of the invention, as long as the effects are not impaired.

[0038] Furthermore, sequestering agents such as disodium edetate, trisodium edetate, sodium citrate, sodium polyphosphate, sodium metaphosphate, and gluconic acid; preservatives such as methylparaben, ethylparaben, and butylparaben; caffeine, tannin, verapamil, tranexamic acid and its derivatives, licorice extract, glabridin, hot water extract of Chinese quince fruit, various herbal medicines, drugs such as tocopherol acetate, glycyrrhizic acid and its derivatives or salts thereof; whitening agents such as vitamin C, magnesium ascorbyl phosphate, ascorbic acid glucoside, arbutin, and kojic acid; and sugars such as glucose, fructose, mannose, sucrose, and trehalose may also be appropriately blended.

[0039] (Form) The cosmetic composition of the present invention may be in any form as long as it can be applied to the skin, and any form may be used, such as a solution system, a solubilized system, an emulsion system, a powder dispersion system, a water-oil two-layer system, a water-oil-powder three-layer system, an ointment, a lotion, a gel, or an aerosol.

[0040] (Usage Form) The cosmetic composition of the present invention can be used, for example, as facial cosmetics such as lotion, emulsion, cream, and pack, as makeup cosmetics such as foundation, lipstick, and eye shadow, as fragrance cosmetics, etc. In particular, the cosmetic composition of the present invention may be a skin care composition including lotion, emulsion, serum, and cream.

[0041] Cosmetic or Non-Therapeutic Method One aspect of the present invention relates to a cosmetic or non-therapeutic method for promoting retention of a compound having an amide bond or an amino group in the stratum corneum, comprising the step of applying the cosmetic composition of the present invention to skin.

[0042] The cosmetic composition of the present invention can be used in cosmetic or non-therapeutic methods for moisturizing human skin (maintaining skin moisture), improving skin luster (imparting smoothness and luster), etc. In cosmetic or non-therapeutic methods according to the present invention, the cosmetic composition of the present invention is applied to the area where the desired effect is desired, such as the face, neck, hands, arms, legs, etc. Application can be carried out in any manner, such as by hand or with an applicator. The number, frequency, amount, etc. of application are appropriately determined depending on the desired effect, etc. It should be noted that the cosmetic or non-therapeutic methods according to the present invention do not include so-called medical procedures.

[0043] Furthermore, one aspect of the present invention relates to the use of the cosmetic composition of the present invention for promoting retention of a compound having an amide bond or an amino group in the stratum corneum. The data disclosed herein demonstrate that sodium dilauroyl glutamate lysine promotes retention of a compound having an amide bond or an amino group in the stratum corneum. Therefore, the cosmetic composition of the present invention can be used to promote retention of a compound having an amide bond or an amino group in the stratum corneum.

[0044] (Miscellaneous) All documents mentioned herein are incorporated by reference in their entirety.

[0045] The following examples and reference examples of the present invention are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the claims. The present invention may be modified, for example, by adding, deleting, or substituting constituent elements of the present invention, provided that the modifications do not depart from the spirit of the present invention.

[0046] Examples and Comparative Examples The following Examples and Comparative Examples demonstrate that a cosmetic composition in which sodium dilauramidoglutamide lysine and a compound having an amide bond or an amino group are dissolved in water has a pH value within a specific range, thereby providing the effect of allowing the compound having an amide bond or an amino group to penetrate into the stratum corneum while maintaining high stability, and in particular inhibiting gelation. In addition, the following Examples and Comparative Examples demonstrate that when the above-mentioned cosmetic composition further comprises a water-soluble polyether-modified silicone and / or a water-soluble polyether-modified silane, it maintains the inhibition of gelation while providing improved usability, and in particular inhibits the stickiness of the cosmetic composition of the present invention.

[0047] Compositions (aqueous compositions) of the examples and comparative examples were prepared using sodium dilauramidoglutamide lysine (DLGL, raw material name: Pellicer L-30 manufactured by Asahi Kasei Finechem Corporation, containing 29% by weight of DLGL), sodium pyrrolidonecarboxylate (PCA-Na, raw material name: AJIDEW N-50 manufactured by Ajinomoto Healthy Supply Co., Ltd., containing 50% by weight of PCA-Na), and other components shown in Tables 1-1 to 1-3.

[0048] In Tables 1-1 to 1-3, the proportion of each component is shown in parts by mass when the total composition is taken as 100 parts by mass. The "added components" in Tables 1-1 to 1-3 are citric acid: 0.01 part by mass, sodium citrate: 0.09 part by mass, EDTA-2Na: 0.1 part by mass, chlorphenesin: 0.2 part by mass, and phenoxyethanol: 0.5 part by mass. In the compositions of the examples and comparative examples, the pH was adjusted using potassium hydroxide as necessary.

[0049] The compositions of these Examples and Comparative Examples were evaluated for moisturizing sensation (moisturizing sensation), ease of use (non-stickiness), and stability (resistance to gelation) according to the following criteria.

[0050] Moisture perception (moisturizing feeling) A (good): All five of the five panelists felt moisturizing. B (average): Three or four of the five panelists felt moisturizing. C (poor): Two or fewer of the five panelists felt moisturizing.

[0051] Stability (resistance to gelation) A (good): No gelation is observed at any temperature range, including low (0°C), room (25°C), and high (50°C). B (moderate): Gelation is observed at both low (0°C) and high (50°C) temperatures, but gelation is resolved at room temperature. C (poor): Gelation is observed at both low (0°C) and high (50°C) temperatures, and gelation is not resolved even at room temperature.

[0052] Usability (non-stickiness) A (good): All five of the five panelists felt that it was non-sticky. B (average): Three or four of the five panelists felt that it was non-sticky. C (poor): Two or less of the five panelists felt that it was non-sticky.

[0053]

[0054]

[0055]

[0056] Reference Examples The following Reference Examples demonstrate that sodium dilauroyl glutamate lysine promotes retention of compounds having an amide bond or an amino group in the stratum corneum.

[0057] Reference Example 1: Stratum corneum penetration of PCA-Na Sodium dilauroyl glutamate lysine (DLGL, raw material name: Pellicer L-30 manufactured by Asahi Kasei Finechem Corporation, containing 29% by weight of DLGL) and sodium pyrrolidone carboxylate (PCA-Na, raw material name: AJIDEW N-50 manufactured by Ajinomoto Healthy Supply Co., Inc., containing 50% by weight of PCA-Na) were used to prepare samples of unapplied material, PCA-Na alone, and PCA-Na and DLGL (PCA-DLGL) as shown in Table 2-1 below. Coating amount: 2μL / cm ２Panel: 5 Japanese males (age: 28.8±1.0) Each sample was applied to the inside of the forearm, and after 24 hours, the subjects washed twice with soap and then stripped the stratum corneum 10 times using D-Squame® stripping disks (Clinical & Derm). After stripping, each disk was immersed in 0.5 mL of 30% aqueous acetonitrile solution, and PCA-Na was extracted by ultrasonic treatment for 15 minutes. PCA-Na was quantified by LCMS. The total amount of PCA-Na was measured in layers 1 to 5, 6 to 10, and all layers from the surface.

[0058] The results are shown in Figure 1. By using both PCA and DLGL, the PCA concentration was particularly high in the shallow layer where leakage is most likely, and it was confirmed that DLGL is effective in retaining PCA-Na in the stratum corneum.

[0059] Reference Example 2: Stratum corneum permeability of proline A similar evaluation was carried out in Reference Example 2, except that PCA-Na was replaced with L(-)proline (Fujifilm Wako Pure Chemical Industries, Ltd.). The results are shown in Figure 2. No significant difference was observed in the amount of stratum corneum permeation after 24 hours when L(-)proline and DLGL were used in combination.

[0060] Reference Example 3: Effect on keratinocytes The above sample was applied to the inside of the forearm of seven Japanese male panelists in their 20s to 40s at a dose of 5 μL / cm ２ The stratum corneum was applied at a volume of 100 ml. After 1 hour, the stratum corneum was peeled off with a Post-it note and transferred to D-Squame® stripping disks (Clinical & Derm), and the keratinocytes were observed under a laser microscope (KEYENCE). The surface roughness (Ra) of the keratinocytes after application of each sample was measured. ΔRa was calculated by subtracting the surface roughness (Ra) after application of water from the surface roughness (Ra) after application of each sample, and the results are shown in Figure 3. It was confirmed that the use of both PCA and DLGL improved the roughness of the keratinocyte surface, making it possible to smooth the surface.

[0061] Reference Example 4: Moisturizing effect of PCA-Na and DLGL The moisture content of the stratum corneum was measured using a SKICON EX-200 (skin surface stratum corneum moisture content measuring device, Yayoi Co., Ltd.) under the following conditions. <SKICON measurement> Application amount: 2 μL / cm ２Panel: 5 Japanese people (age: 30.2±2.6 years). Analysis was performed on 4 people, excluding one panelist who developed redness. No application, PCA-Na alone, and PCA-Na and DLGL (PCA-DLGL) samples were applied, and measurements were taken 1, 6, and 24 hours later, after washing once with soap.

[0062] The difference in SKICON value from before application is shown in Figure 4. When PCA-Na and DLGL were applied, high SKICON values ​​were maintained even after 24 hours, confirming that the moisture content was maintained in the shallow surface layer.

[0063] Reference Example 5: Interaction between each compound and DLGL The presence or absence of an interaction between the stored target compound and DLGL was evaluated by measuring changes in IR spectrum (NICOLET iS50ATR, Thermo). The number of scans was set to 32. The evaluation was determined by the presence or absence of a shift in the absorption spectrum of a specific bond of the compound when the amount of DLGL relative to PCA was increased. The peak shift in the IR spectrum indicates a change in the environment around each functional group, confirming that the two compounds are interacting. The results of the interaction between PCA-Na and DLGL are shown in Table 2-2. In terms of weight ratio, the peak shifted at DLGL additions of at least 0.23 or more relative to PCA1, confirming that DLGL interacts with PCA-Na even at low concentrations.

[0064] The results of the interactions between L-asparagine monohydrate, uridine, L(+)-lysine hydrochloride and DLGL are shown in Tables 2-3.

[0065] Table 2-3 shows the IR peaks measured for samples of L-asparagine monohydrate (Fujifilm Wako Pure Chemical Industries), uridine (Fujifilm Wako Pure Chemical Industries), and L-lysine hydrochloride (Fujifilm Wako Pure Chemical Industries), as well as samples prepared by adding DLGL to each compound at a weight ratio of 1. The addition of DLGL shifted the peaks near the amide bond of L-asparagine monohydrate and uridine and the amino group of L(+)-lysine hydrochloride, confirming that DLGL interacts with the amide bond and amino group of each compound.

[0066] Reference Example 6: Water retention capacity of PCA-Na and DLGL The heat of fusion was measured under the following conditions using differential scanning calorimetry (DSC, TA Q-2000, TA Instruments) to calculate the proportion of frozen water and the proportion of unfrozen water, and the amount of bound water in PCA-Na and DLGL was measured.

[0067] Step size: 1°C / min Temperature: 25°C → -50°C → 25°C Sample: 11% solids

[0068] Calculation method: Proportion of frozen water = heat of fusion of 1 g of water in each sample / heat of fusion of 1 g of pure water Proportion of unfrozen water = 1 - proportion of frozen water Unfrozen water was converted into unfrozen combined water.

[0069] The results are shown in Table 2-4. It was confirmed that the amount of bound water did not change up to a weight ratio of 1, but the proportion of unfrozen bound water decreased at a weight ratio of 2 or more.

[0070] Reference Example 7: Permeability of PCA-Na through isolated stratum corneum Sodium dilauroyl glutamate lysine (DLGL, raw material name: Pellicer L-30 manufactured by Asahi Kasei Finechem Corporation, containing 29% by weight of DLGL) and sodium pyrrolidone carboxylate (PCA-Na, raw material name: AJIDEW N-50 manufactured by Ajinomoto Healthy Supply Co., Ltd., containing 50% by weight of PCA-Na) were used to prepare samples of PCA-Na alone (PCA), PCA-Na and DLGL (PCA-DLGL) as shown in Table 2-5 below. Water was used as a control.

[0071]

[0072] A 1-cm-diameter circle was excised from the dorsal skin of a 39-year-old Caucasian male using a punch. The epidermal side was coated with Aron Alpha A "Sankyo" (Toa Gosei Co., Ltd.) and attached to a Teflon™ sheet. The resulting stratum corneum specimen was immersed in the prepared sample for 5 minutes (n=4). After immersion, the specimen was removed and allowed to stand overnight in a room. It was then washed three times with MilliQ water and allowed to stand overnight. The stratum corneum specimen was placed in 1 mL of 30% aqueous acetonitrile and extracted ultrasonically for 20 minutes. PCA-Na was quantified by LCMS. The results are shown in Figure 5. While the PCA concentration in water was below the lower limit of quantitation (BLQ), the use of both PCA and DLGL enhanced its penetration into the stratum corneum.

[0073] Reference Example 8: Effect of PCA-Na on keratinocytes in isolated stratum corneum Sodium dilauroyl glutamate lysine (DLGL, raw material name: Pellicer L-30 manufactured by Asahi Kasei Finechem Corporation, containing 29% by weight of DLGL) and sodium pyrrolidone carboxylate (PCA-Na, raw material name: AJIDEW N-50 manufactured by Ajinomoto Healthy Supply Co., Ltd., containing 50% by weight of PCA-Na) were used to prepare samples of PCA-Na alone (PCA), PCA-Na and DLGL (PCA-DLGL) as shown in Table 2-6 below. Water was used as a control.

[0074]

[0075] Stratum corneum samples were collected from four male subjects in their 20s to 40s by attaching Post-it notes to the inner forearms. The adhesive layer of the Post-it note was attached to the adhesive layer of D-Squame® standard sampling disks (Clinical & Derm, Inc.), and the stratum corneum was transferred. The disks were immersed in each aqueous solution of the sample for 5 seconds and allowed to dry overnight. The keratinocytes were observed using a laser microscope (KEYENCE), and the surface roughness (Ra) of the keratinocytes after immersion in each sample was measured. The results are shown in Figure 6. It was confirmed that the use of both PCA and DLGL improved the roughness of the keratinocyte surface, resulting in a smoother surface.

[0076] As is clear from the results in Figures 1 to 6, the use of DLGL, a stratum corneum retention promoter, allows the PCA-Na concentration in the stratum corneum to be maintained even long after application, confirming that DLGL is effective in retaining PCA-Na in the stratum corneum. It was confirmed that the use of both PCA-Na and DLGL improves the roughness of the keratinocyte surface, smoothing the surface. Furthermore, it was confirmed that this stratum corneum retention effect is effective in increasing the moisture content in the shallow, superficial layer of the stratum corneum, close to the skin's surface. It was confirmed that retention in the stratum corneum for long periods after application is due to molecular interactions with the target compound. Therefore, it was suggested that the stratum corneum retention composition containing the stratum corneum retention promoter of the present invention is effective for use as a moisturizer that provides moisture to the skin and a gloss-improving agent.

Claims

1. A cosmetic composition comprising dilauroyl glutamate lysine sodium, a compound having an amide bond or an amino group, and water, wherein the dilauroyl glutamate lysine sodium and the compound having an amide bond or an amino group are dissolved in the water, and the pH value at 25 °C is 6.3 or more.

2. The cosmetic composition according to claim 1, further comprising a water-soluble polyether-modified silicone and / or a water-soluble polyether-modified silane.

3. The cosmetic composition according to claim 2, wherein the water-soluble polyether-modified silicone comprises PEG-10 methyl ether dimethicone and / or PEG / PPG-30 / 10 dimethicone.

4. The cosmetic composition according to claim 2, wherein the water-soluble polyether-modified silane comprises bis PEG-18 methyl ether dimethylsilane.

5. The cosmetic composition according to claim 2, wherein the water-soluble polyether-modified silicone or the water-soluble polyether-modified silane is 20 to 300 parts by mass based on 100 parts by mass in total of the compound having an amide bond or an amino group and the dilauroyl glutamate lysine sodium.

6. The cosmetic composition according to any one of claims 1 to 5, wherein the compound having an amide bond or an amino group is a natural moisturizing factor (NMF).

7. The cosmetic composition according to any one of claims 1 to 5, wherein the compound having an amide bond or an amino group comprises at least one selected from the group consisting of asparagine, lysine, pyrrolidone carboxylic acid and its salts, and uridine.

8. The cosmetic composition according to any one of claims 1 to 5, wherein the mass ratio of the dilauroyl glutamate lysine sodium to the compound having an amide bond or an amino group (dilauroyl glutamate lysine sodium / the compound having an amide bond or an amino group) is 0.01 or more.

9. The cosmetic composition according to any one of claims 1 to 5, wherein the mass ratio of the dilauroyl glutamate lysine sodium to the compound having an amide bond or an amino group (dilauroyl glutamate lysine sodium / the compound having an amide bond or an amino group) is 1.0 or less.

10. The cosmetic composition according to any one of claims 1 to 5, which is used in a skin care composition including lotion, emulsion, essence, and cream.

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