JP7579043B2 - Composition - Google Patents

Description

The present invention relates to a composition containing an N-acylamino acid ester and a polyhydric alcohol.

Maintaining moisture in the skin is important for maintaining skin health. To maintain moisture in the skin, moisturizers such as emollients and polyhydric alcohols are used. For example, a technique has been reported in which an emollient and a polyhydric alcohol are used in combination to achieve better moisturizing properties (Patent Document 1).

The stratum corneum has two functions: a moisturizing function that retains moisture inside, and a barrier function that prevents the intrusion of foreign substances (e.g., foreign bodies, viruses, and bacteria) from the outside world. Substances that affect the stratum corneum's functions include sebum, intercellular lipids, and natural moisturizing factors.

Profilaggrin stored in the granular layer of skin tissue undergoes dephosphorylation and is broken down into filaggrin during keratinization. Filaggrin migrates from the granular layer to the stratum corneum, where it binds to and aggregates with keratin fibers to form a keratin pattern. Filaggrin is then broken down into low molecular weight substances such as urocanic acid, which become natural moisturizing factors involved in water retention and UV absorption. Therefore, it is believed that the more the production of filaggrin is promoted, the greater the amount of the natural moisturizing factors that are its decomposition products, and the better the skin's moisturizing ability.

The keratinocytes that make up the stratum corneum and the intercellular lipids that exist between the keratinocytes prevent foreign substances from entering from the outside world. Therefore, if the number or size of the keratinocytes is insufficient, gaps will appear in the stratum corneum, reducing its barrier function.

Around keratinocytes, which contain structures formed by the aggregation of keratin such as keratin 10 and filaggrin, there exists the marginal zone, which is an extremely tough and huge insoluble structure that lines the cell membrane of keratinocytes. The main structural elements of the marginal zone are proteins such as involucrin produced in spinous cells and loricrin produced in granular cells, which are cross-linked by enzymes such as transglutaminase (TG) 1. Therefore, filaggrin, involucrin, transglutaminase 1, keratin 10, and loricrin are thought to strongly affect the formation of keratinocytes and are related to the barrier function of the skin.

It has been reported that the expression of filaggrin, involucrin, transglutaminase 1, keratin 10, and loricrin is promoted by certain peptides such as glycylproline (Patent Document 2).

JP 2000-53524 A International Publication No. 2014/175001

In the technology of using an emollient and a polyhydric alcohol in combination, it was necessary to use an emulsifier that can cause skin irritation in order to mix these ingredients. Furthermore, a large amount of emulsifier is required to stably blend highly polar oils such as acylamino acid esters (see, for example, the examples (Tables I and II) of WO 93/05129). A large amount of emulsifier increases irritation to the skin and there was concern that it could weaken the skin's barrier function.

In addition, certain peptides such as glycylproline not only have a weak effect of promoting the expression of proteins that make up the barrier tissue in the skin, but also have no moisturizing or emollient properties, meaning that they cannot be used as an approach to improve moisture retention.

The object of the present invention is to provide a moisturizing component that can be easily used in combination with a polyhydric alcohol, and a composition that contains a polyhydric alcohol.

After extensive research, the inventors have found that a specific N-acyl amino acid ester is a promising moisturizing ingredient. The inventors have also found that such a specific N-acyl amino acid ester is an excellent ingredient that can be easily used in combination with a polyhydric alcohol. Based on this knowledge, the inventors have succeeded in providing a composition that contains a specific N-acyl amino acid ester and a polyhydric alcohol, and have completed the present invention.

That is, the present invention is as follows.
[1] The following formula (1):

[Wherein,
A is a linear or branched hydrocarbon group having 1 to 17 carbon atoms;
B is a linear or branched hydrocarbon group having 2 to 18 carbon atoms;
and X is a hydrogen atom or a linear or branched hydrocarbon group having 1 to 5 carbon atoms.
[2] The compound represented by the formula (1) is selected from the group consisting of the following formulas (2) to (6):

[Wherein,
A is a linear or branched hydrocarbon group having 1 to 17 carbon atoms;
B is a linear or branched hydrocarbon group having 2 to 18 carbon atoms.
[3] The composition of either [1] or [2], wherein A is a linear or branched hydrocarbon group having 1 to 11 carbon atoms.
[4] The composition according to any one of [1] to [3], wherein B is a linear or branched hydrocarbon group having 2 to 8 carbon atoms.
[5] The composition of [4], wherein B is a linear or branched hydrocarbon group having 2 or 3 carbon atoms.
[6] The composition according to any one of [1] to [5], wherein the hydrocarbon group in A, B and X is an alkyl group.
[7] The composition according to any one of [1] to [6], wherein the polyhydric alcohol is a dihydric alcohol or a trihydric alcohol.
[8] The composition according to any one of [1] to [7], wherein the polyhydric alcohol is contained in the composition in an amount of 0.5 parts by weight or more per part by weight of the compound.
[9] The composition according to any one of [1] to [8], wherein the compound has a concentration of 0.01 to 1000 mM.
[10] The composition according to any one of [1] to [9], wherein the composition is a moisturizer.
[11] Any of the compositions according to [1] to [10], wherein the composition has the ability to improve skin barrier function.
[12] The composition according to any one of [1] to [11], wherein the composition is an external preparation for skin.
[13] The composition according to any one of [1] to [11], wherein the composition is a cosmetic.
[14] The composition according to [13], wherein the cosmetic is a leave-on cosmetic.

The composition of the present invention can be stably formulated with polyhydric alcohols within an effective concentration range.
The composition of the present invention also contains a polyhydric alcohol, which improves wettability and compatibility with the skin.
The composition of the present invention can further significantly improve moisture retention in the skin. For example, the improvement in moisture retention in the skin can be achieved from outside the skin, inside the skin, or both, by the moisturizing effect of the polyhydric alcohol and the moisturizing effect of the N-acylamino acid ester.
The composition of the present invention is also excellent in terms of safety to the skin, since no cytotoxicity is observed even when the acyl chain length in the N-acylamino acid ester is long.
The composition of the present invention can exhibit a transparent property even when it contains a hydrophobic organic solvent (oil) and/or a hydrophilic organic solvent, and therefore can impart a luxurious appearance and can avoid visual effects on the skin. Therefore, the composition of the present invention has an advantage that, for example, white residue caused by application can be reduced.

1 is a diagram showing the amplification amount (relative value to the amplification amount of the control) of each moisturizing-related protein gene of octanoylvaline (Example 3: C8Val), octanoylalanine (Example 4: C8Ala), glycylproline (Comparative Example 2: Gly-Pro), and valine (Comparative Example 3: Val). The moisturizing-related protein genes tested are, from the left, genes encoding filaggrin, involucrin, transglutaminase 1 (TG1), keratin 10, and loricrin (similar to FIG. 2). FIG. 2 is a diagram showing the amplification amount (relative value to the amplification amount of the control) of each moisturizing-related protein gene for octanoyl leucine (Example 5: C8Leu), octanoyl isoleucine (Example 6: C8Ile), octanoyl glycine (Example 7: C8Gly), glycylproline (Comparative Example 2: Gly-Pro), and valine (Comparative Example 3: Val). 3 is a diagram showing the amplification amount (relative value to the amplification amount of the control) of each moisturizing-related protein gene of butanoyl valine (Example 8: C4Val), hexanoyl valine (Example 9: C6Val), octanoyl valine (Example 10: C8Val), decanoyl valine (Example 11: C10Val), dodecanoyl valine (Example 12: C12Val) and methanoyl valine (Example 13: C2Val). The moisturizing-related protein genes tested are, from the left, genes encoding filaggrin, involucrin, and transglutaminase 1 (TG1). FIG. 4 shows the amount of amplification of the filaggrin gene (relative to the amount of amplification of the control) for lauroyl valine (Example 14: C12Val), decanoyl valine (Example 15: C10Val), octanoyl valine (Example 16: C8Val), hexanoyl valine (Example 17: C6Val), butanoyl valine (Example 18: C4Val), and acetyl valine (Example 19: C2Val). FIG. 5 shows the amount of amplification of the filaggrin gene (relative to the amount of amplification of the control) for lauroylalanine (Example 20: C12Ala), decanoylalanine (Example 21: C10Ala), octanoylalanine (Example 22: C8Ala), hexanoylalanine (Example 23: C6Ala), and butanoylalanine (Example 24: C4Ala). FIG. 6 shows the absorbance of lauroyl valine (Comparative Example 4: C12Val), decanoyl valine (Example 25: C10Val), octanoyl valine (Example 26: C8Val), hexanoyl valine (Example 27: C6Val), butanoyl valine (Example 28: C4Val), and acetyl valine (Example 29: C2Val) in cells (percentage of the absorbance of the control). 7 shows HPLC (Shimadzu) chromatograms (measurement wavelength 210 nm) of N-octanoylalanine produced by hydrolysis of C8Ala-iPA in the presence or absence of esterase. In the chromatogram, a peak for N-octanoylalanine is observed at elution time 0.6 minutes, and a peak for C8Ala-iPA is observed at elution time 1.7 minutes. When C8Ala-iPA is reacted with esterase, the peak at 1.7 minutes decreases, and a new peak appears at 0.6 minutes. 8 shows HPLC (Shimadzu) chromatograms (measurement wavelength 210 nm) of N-octanoylalanine produced by hydrolysis of C8Ala-Et in the presence or absence of esterase. On the chromatogram, a peak for N-octanoylalanine is observed at elution time 0.6 minutes, and a peak for C8Ala-Et is observed at elution time 1.2 minutes. When C8Ala-Et is reacted with esterase, the peak at 1.2 minutes decreases, and a new peak appears at 0.6 minutes.

The present invention provides a composition containing a compound represented by the above formula (1) and a polyhydric alcohol.

(I) Compound represented by the above formula (1) A is a linear or branched hydrocarbon group having 1 to 17 carbon atoms. The number of carbon atoms in the hydrocarbon group in A may be preferably 16 or less, more preferably 15 or less, even more preferably 13 or less, and even more preferably 11 or less. The number of carbon atoms in the hydrocarbon group in A may also be 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more. More specifically, the number of carbon atoms in the hydrocarbon group in A may be preferably 2 to 16, more preferably 3 to 15, even more preferably 4 to 13, and even more preferably 5 to 11. The hydrocarbon group in A is saturated or unsaturated. Examples of such hydrocarbon groups include alkyl, alkenyl, and alkynyl.

When A is an alkyl, the alkyl is a straight-chain or branched-chain alkyl having 1 to 17 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkyl in A are the same as the number of carbon atoms of the hydrocarbon group in A described above. Examples of the alkyl in A include methyl, ethyl, propyl (e.g., n-propyl, isopropyl), butyl (e.g., n-butyl, iso-butyl, sec-butyl, tert-butyl), pentyl (e.g., n-pentyl, iso-pentyl, neo-pentyl, 1-ethylpropyl), hexyl (e.g., n-hexyl, iso-hexyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 2-ethylbutyl), heptyl (e.g., n-heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 1,1-dimethylpentyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2-ethylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4-dimethylpentyl, 1,5-dimethylpentyl, 1,6-dimethylpentyl, 1,7-dimethylpentyl, 1,8-dimethylpentyl, 1,9-dimethylpentyl, 2,10-dimethylpentyl, 2,20-dimethylpentyl, 2,30-dimethylpentyl, 2,40-dimethylpentyl, 2,50-dimethylpentyl, 2,60-dimethylpentyl, 2,70-dimethylpentyl, 2,80-dimethylpentyl, 2,90-dimethylpentyl, 2,10-dimethylpentyl, 2,110-dimethylpentyl, 2,20-dimethylpentyl, 2,210-dimethylpentyl, 2,220-dimethylpentyl, 2,210-dimethylpentyl, 2,220-dimethylpentyl, 2,2 yl), octyl (e.g., n-octyl, 1-methylheptyl, 2-methylheptyl, 3-methylheptyl, 1,1-dimethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 2-ethylhexyl), nonyl (e.g., n-nonyl, 3,5,5-trimethylhexyl), decanyl (e.g., n-decanyl), undecanyl (e.g., n-undecanyl), dodecanyl (e.g., n-dodecanyl), tridecanyl (e.g., n-tridecanyl), tetradecanyl (e.g., n-tetradecanyl), pentadecanyl (e.g., n-pentadecanyl), hexadecanyl (e.g., n-hexadecanyl), and heptadecanyl (e.g., n-heptadecanyl).

When A is alkenyl, the alkenyl is a straight or branched alkenyl having 2 to 17 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkenyl in A are the same as the number of carbon atoms of the hydrocarbon group in A described above. Examples of the alkenyl in A include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, and heptadecenyl.

When A is alkynyl, the alkynyl is a straight or branched alkynyl having 2 to 17 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkynyl in A are the same as the number of carbon atoms of the hydrocarbon group in A described above. Examples of the alkynyl in A include ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl, decynyl, undecynyl, dodecynyl, tridecynyl, tetradecynyl, pentadecynyl, hexadecynyl, and heptadecynyl.

Preferably, A is a linear or branched alkyl having 1 to 17 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkyl in A are the same as the number of carbon atoms of the hydrocarbon group in A described above. Specific examples of such alkyl are as described above.

In a specific embodiment, the group in A may have 7 to 17 carbon atoms (preferably 7 to 11, more preferably 8 to 11). When the group in A has 7 or more carbon atoms, the compound represented by the above formula (1) has the advantage of being able to significantly induce the expression of genes encoding various proteins related to the improvement of stratum corneum function, and is not cytotoxic. Examples of such proteins include proteins that can generate natural moisturizing factors in skin tissue (e.g., filaggrin, profilaggrin), and proteins that can be involved in skin barrier function (e.g., filaggrin, involucrin, transglutaminase 1, keratin 10, loricrin).

In another specific embodiment, the number of carbon atoms in the group in A may be 6 or less. When the number of carbon atoms in the group in A is 6 or less, the compound represented by the above formula (1) has a partition coefficient (Log P) in the range of 1 to 4 and a molecular weight of 500 Da or less, and therefore has the advantage of being excellent in transdermal absorbability and being able to be provided at a high concentration in the stratum corneum.

B is a straight or branched chain hydrocarbon group having 2 to 18 carbon atoms. The number of carbon atoms in the hydrocarbon group in B is preferably 2 to 15, more preferably 2 to 12, even more preferably 2 to 8, even more preferably 2 to 6, and particularly preferably 2 or 3. The hydrocarbon group in B is saturated or unsaturated. Examples of such hydrocarbon groups include alkyl, alkenyl, and alkynyl.

When B is an alkyl, the alkyl is a straight-chain or branched-chain alkyl having 2 to 18 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkyl in B are the same as the number of carbon atoms of the hydrocarbon group in B described above. Examples of the alkyl in B include ethyl, propyl (e.g., n-propyl, isopropyl), butyl (e.g., n-butyl, iso-butyl, sec-butyl, tert-butyl), pentyl (e.g., n-pentyl, iso-pentyl, neo-pentyl, 1-ethylpropyl), hexyl (e.g., n-hexyl, iso-hexyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 2-ethylbutyl), heptyl (e.g., n-heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 1,1-dimethylpentyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2-ethylpentyl), octyl (e.g., n-oct ...1-methylhexyl, octyl, 1-methylheptyl, 2-methylheptyl, 3-methylheptyl, 1,1-dimethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 2-ethylhexyl), nonyl (e.g., n-nonyl, 3,5,5-trimethylhexyl), decanyl (e.g., n-decanyl), undecanyl (e.g., n-undecanyl), dodecanyl (e.g., n-dodecanyl), tridecanyl (e.g., n-tridecanyl), tetradecanyl (e.g., n-tetradecanyl), pentadecanyl (e.g., n-pentadecanyl), hexadecanyl (e.g., n-hexadecanyl), heptadecanyl (e.g., n-heptadecanyl), and octadecanyl (e.g., n-octadecanyl).

When B is alkenyl, the alkenyl is a straight or branched alkenyl having 2 to 18 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkenyl in B are the same as the number of carbon atoms of the hydrocarbon group in B described above. Examples of the alkenyl in B include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, and octadecenyl.

When B is alkynyl, the alkynyl is a straight or branched alkynyl having 2 to 18 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkynyl in B are the same as the number of carbon atoms of the hydrocarbon group in B described above. Examples of the alkynyl in B include ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl, decynyl, undecynyl, dodecynyl, tridecynyl, tetradecynyl, pentadecynyl, hexadecynyl, heptadecynyl, and octadecynyl.

Preferably, B is a linear or branched alkyl having 2 to 18 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkyl in B are the same as the number of carbon atoms of the hydrocarbon group in B described above. Specific examples of such alkyl are as described above.

X is a hydrogen atom or a linear or branched hydrocarbon group having 1 to 5 carbon atoms. The number of carbon atoms in the hydrocarbon group in X may be, for example, 1 to 4. The hydrocarbon group in X is saturated or unsaturated. Examples of such hydrocarbon groups include alkyl, alkenyl, and alkynyl.

When X is an alkyl, the alkyl is a straight-chain or branched-chain alkyl having 1 to 5 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkyl in X are the same as the number of carbon atoms of the hydrocarbon group in X described above. Examples of the alkyl in X include methyl, ethyl, propyl (e.g., n-propyl, isopropyl), butyl (e.g., n-butyl, iso-butyl, sec-butyl, tert-butyl), and pentyl (e.g., n-pentyl, iso-pentyl, neo-pentyl, 1-ethylpropyl).

When X is alkenyl, the alkenyl is a straight-chain or branched-chain alkenyl having 2 to 5 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkenyl in X are the same as the number of carbon atoms of the above-mentioned hydrocarbon group in X. Examples of the alkenyl in X include ethenyl, propenyl, butenyl, and pentenyl.

When X is alkynyl, the alkynyl is a straight-chain or branched-chain alkynyl having 2 to 5 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkynyl in X are the same as the number of carbon atoms of the above-mentioned hydrocarbon group in X. Examples of the alkynyl in X include ethynyl, propynyl, butynyl, and pentynyl.

Preferably, X is a linear or branched alkyl having 1 to 5 carbon atoms. Examples and preferred examples of the number of carbon atoms of the alkyl in X are the same as the number of carbon atoms of the hydrocarbon group in X described above. Specific examples of such alkyl are as described above.

In a specific embodiment, the composition of the present invention may contain a compound represented by the above formula (1) (wherein A is a linear or branched chain hydrocarbon group having 2 to 10 carbon atoms, B is a linear or branched chain hydrocarbon group having 2 to 18 carbon atoms, and X is a linear or branched chain hydrocarbon group having 1 to 5 carbon atoms).)

Preferably, the compound represented by the above formula (1) is a compound represented by any one of the above formulas (2) to (6). With respect to A and B in the compounds represented by the above formulas (2) to (6), the definitions, examples, preferred examples and specific examples of the hydrocarbon group (e.g., alkyl, alkenyl, alkynyl) and the number of carbon atoms are the same as those described above for formula (1).

In a specific embodiment, A and B in the compounds represented by the above formulas (2) to (6) may each independently have a different number of carbon atoms and a different hydrocarbon group. For example, A in the compounds represented by the above formulas (2) to (4) may be a linear or branched chain hydrocarbon group having 2 to 17 carbon atoms, and A in the compounds represented by the above formulas (5) and (6) may be a linear or branched chain hydrocarbon group having 6 or less carbon atoms, or 7 to 17 (preferably 7 to 11, more preferably 8 to 11) carbon atoms. Also, A in the compounds represented by the above formulas (2) to (4) may be a linear or branched chain hydrocarbon group having 2 to 11 carbon atoms, and A in the compounds represented by the above formulas (5) and (6) may be a linear or branched chain hydrocarbon group having 7 to 11 carbon atoms (preferably 8 to 11). Furthermore, A in the compounds represented by (2) to (4) above may be a linear or branched chain hydrocarbon group having 5 to 11 carbon atoms, and A in the compounds represented by (5) and (6) above may be a linear or branched chain hydrocarbon group having 7 to 11 carbon atoms (preferably 8 to 11).

The compounds represented by formulas (1) to (6) correspond to N-acyl neutral amino acid esters (neutral amino acid derivatives). The compounds represented by formulas (1) to (6) may be optical isomers (L or D form) with respect to the nitrogen atom, the carbon atom of the carbonyl group, and the carbon atom to which X is bonded, or may be a mixture thereof. Preferably, the compounds represented by formulas (1) to (6) are L forms.

The preparation of the compound contained in the composition of the present invention can be suitably carried out by reacting an N-acyl neutral amino acid and an alcohol. The reaction of an N-acyl neutral amino acid and an alcohol can be carried out by a general method for producing an ester from a carboxylic acid compound and an alcohol. Such reactions are well known in the art. For example, the reaction can be carried out by appropriately adding a catalyst. The reaction can also be carried out at an appropriate temperature (e.g., 15 to 200°C) for several hours (e.g., 0.5 to 8 hours). More specifically, the preparation of the compound contained in the composition of the present invention can be carried out by the method of Production Example A described below. The preparation of the compound of the present invention can also be carried out in the same manner as the method described in JP-A-11-240828, except that the types of N-acyl neutral amino acid and alcohol are changed in the method described in JP-A-11-240828. The compound contained in the composition of the present invention can be suitably purified by any purification method (e.g., extraction) used in the field of organic synthesis.

(II) Polyhydric Alcohols Examples of polyhydric alcohols include dihydric alcohols (e.g., ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butanediol, 2-butene-1,4-diol, 1,5-pentanediol, 1,2-pentanediol, isoprene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, monoglycerides (monoacylglycerols)), trihydric alcohols (e.g., glycerin, trimethylolpropane), tetrahydric alcohols (e.g., diglycerin, pentaerythritol, 1,2,6-hexanetriol), alcohols with higher valences, and salts thereof (e.g., salts as described below). Examples of higher hydric alcohols include sugar alcohols which may be substituted (e.g., monosaccharide alcohols such as sorbitol, mannitol, sucrose, glucose, mannose, etc., disaccharide alcohols such as trehalose, etc., and polysaccharide alcohols such as hyaluronic acid, xanthan gum, etc.), as well as polymers of dihydric to tetrahydric alcohols as described above (e.g., polyglycols, polyglycerins), and salts thereof (e.g., salts as described below). The polyhydric alcohol may preferably be a dihydric to tetrahydric alcohol, and more preferably a dihydric or trihydric alcohol.

(III) Details of the composition The content of the compound represented by formula (1) in the composition of the present invention is not particularly limited as long as the compound represented by formula (1) alone or the compound represented by formula (1) in combination with other components can improve the moisturizing property of the composition containing polyhydric alcohol. Such components include, for example, gelling agents (e.g., dibutyl lauroyl glutamide) and thickeners (e.g., thickeners such as carboxyvinyl polymers described below). In the composition of the present invention, when the compound represented by formula (1) is used in combination with other components, the moisturizing property of the composition can be improved while reducing the content of other components. When the compound represented by formula (1) is used in combination with other components, the content of the compound represented by formula (1) is not particularly limited as long as it is an amount that can contribute to reducing the content of other components to improve moisturizing property. For example, when the compound represented by formula (1) is used in combination with other components, the weight ratio of the compound represented by formula (1) to the other components in the composition of the present invention is not particularly limited, but may be, for example, less than 4 parts by weight, preferably less than 2 parts by weight, more preferably less than 1 part by weight, even more preferably less than 0.75 parts by weight, and particularly preferably less than 0.5 parts by weight or less than 0.25 parts by weight, per 1 part by weight of the compound represented by formula (1).

More specifically, the content of the compound represented by formula (1) in the composition of the present invention, either by the compound represented by formula (1) alone or by a combination of the compound represented by formula (1) and other components, may vary depending on the presence or absence of other components, as well as the type and amount of the compound represented by formula (1), the polyhydric alcohol, and other components, and may be, for example, 0.01% (wt) or more, preferably 0.05% (wt) or more, more preferably 0.10% (wt) or more, and even more preferably 0.20% (wt) or more. The content may also be, for example, 90% (wt) or less, preferably 80% (wt) or less, more preferably 70% (wt) or less, and even more preferably 60% (wt) or less. More specifically, the content may be, for example, 0.01 to 90% (wt), preferably 0.05 to 80% (wt), more preferably 0.10 to 70% (wt), and even more preferably 0.20 to 60% (wt). The composition of the present invention may contain one or more (e.g., two, three, or four) types of compounds represented by formula (1).

The content of the polyhydric alcohol in the composition of the present invention may be, for example, 0.1% (wt) or more, preferably 0.5% (wt) or more, more preferably 1.0% (wt) or more, and even more preferably 2.0% (wt) or more. The content may also be, for example, 99% (wt) or less, preferably 98% (wt) or less, more preferably 96% (wt) or less, and even more preferably 95% (wt) or less. More specifically, the content may be, for example, 0.1 to 99% (wt), preferably 0.5 to 98% (wt), more preferably 1.0 to 96% (wt), and even more preferably 2.0 to 95% (wt). The composition of the present invention may contain one or more types of polyhydric alcohol (e.g., two, three, or four types).

In the composition of the present invention, the amount of polyhydric alcohol relative to 1 part by weight of the compound represented by formula (1) may be, for example, 0.5 parts by weight or more, preferably 0.75 parts by weight or more, more preferably 1.0 parts by weight or more, even more preferably 2.0 parts by weight or more, and particularly preferably 5.0 parts by weight or more, although it varies depending on the presence or absence of other components, and the type and amount of the compound represented by formula (1), polyhydric alcohol, and other components. Such an amount may also be, for example, 200 parts by weight or less, preferably 100 parts by weight or less, more preferably 80 parts by weight or less, even more preferably 60 parts by weight or less, and particularly preferably 40 parts by weight or less. More specifically, the amount of polyhydric alcohol relative to 1 part by weight of the compound represented by formula (1) may be, for example, 0.5 to 200 parts by weight, preferably 0.75 to 100 parts by weight, more preferably 1.0 to 80 parts by weight, even more preferably 2.0 to 60 parts by weight, and particularly preferably 5.0 to 40 parts by weight.

The composition of the present invention may further contain water. The water in the composition of the present invention may be provided by adding an aqueous solution to the compound represented by formula (1) and the polyhydric alcohol. The aqueous solution may or may not have a buffering capacity. Examples of the aqueous solution include water (e.g., distilled water, sterile distilled water, purified water, physiological saline), aqueous phosphate solution (buffer solution), Tris-hydrochloric acid buffer, TE (Tris-EDTA) buffer, carbonate-bicarbonate buffer, aqueous boric acid solution (buffer solution), aqueous tartaric acid solution (buffer solution), hydrochloric acid-potassium chloride buffer, glycine-hydrochloric acid buffer, glycine-sodium hydroxide buffer, aqueous citric acid solution (buffer solution), citric acid-phosphate buffer, and aqueous acetic acid solution (buffer solution). The water in the composition of the present invention may be derived from one or more (e.g., two, three, or four) aqueous solutions.

The water content in the composition of the present invention is not particularly limited and may vary depending on the formulation of the composition of the present invention, but may be, for example, 10% (wt) or more, preferably 20% (wt) or more, more preferably 25% (wt) or more, and even more preferably 30% (wt) or more. The water content may also be, for example, 95% (wt) or less, preferably 90% (wt) or less, more preferably 85% (wt) or less, and even more preferably 80% (wt) or less. More specifically, the water content may be, for example, 10 to 95% (wt), preferably 20 to 90% (wt), more preferably 25 to 85% (wt), and even more preferably 30 to 80% (wt).

In the composition of the present invention, the weight percentage of the compound represented by formula (1) relative to water may be, for example, 0.1% or more, preferably 0.15% or more, more preferably 0.2% or more, even more preferably 0.25% or more, and particularly preferably 0.3% or more, although this may vary depending on the presence or absence of other components, the type and amount of the compound represented by formula (1), the polyhydric alcohol, and other components, and the formulation of the composition of the present invention. The weight percentage may also be, for example, 99% or less, preferably 98% or less, more preferably 97% or less, even more preferably 96% or less, and particularly preferably 95% or less. More specifically, the weight percentage may be, for example, 0.1 to 99%, preferably 0.5 to 98%, more preferably 1.0 to 97%, even more preferably 1.5 to 96%, and particularly preferably 2.0 to 95%.

In addition to the above-mentioned components, the composition of the present invention may further contain one or more (e.g., two, three, or four) active ingredients having any action (e.g., biological action or chemical action). Such active ingredients include, for example, low molecular weight compounds.

The term "low molecular weight compound" refers to a compound with a molecular weight of 1500 or less. A low molecular weight compound is a natural or synthetic compound. The molecular weight of a low molecular weight compound may be 1200 or less, 1000 or less, 900 or less, 800 or less, 700 or less, 600 or less, 500 or less, 400 or less, or 300 or less. The molecular weight of a low molecular weight compound may also be 30 or more, 40 or more, or 50 or more. Examples of low molecular weight compounds include amino acids, oligopeptides, vitamins, nucleosides, nucleotides, oligonucleotides, monosaccharides, oligosaccharides, lipids, fatty acids, and metabolites thereof, as well as salts thereof. Such low molecular weight compounds may be moisturizers, skin whitening agents, or hair growth agents.

Examples of salts include salts with inorganic acids, organic acids, inorganic bases, organic bases, and amino acids. Examples of salts with inorganic acids include salts with hydrogen chloride, hydrogen bromide, phosphoric acid, sulfuric acid, and nitric acid. Examples of salts with organic acids include salts with formic acid, acetic acid, trifluoroacetic acid, lactic acid, tartaric acid, fumaric acid, oxalic acid, maleic acid, citric acid, succinic acid, malic acid, benzenesulfonic acid, p-toluenesulfonic acid, and pyrrolidone carboxylic acid. Examples of salts with inorganic bases include salts with alkali metals (e.g., sodium, potassium), alkaline earth metals (e.g., calcium, magnesium), and other metals such as zinc and aluminum, as well as ammonium. Examples of salts with organic bases include salts with trimethylamine, triethylamine, propylenediamine, ethylenediamine, pyridine, ethanolamine, monoalkylethanolamine, dialkylethanolamine, diethanolamine, and triethanolamine. Examples of salts with amino acids include salts with basic amino acids (e.g., arginine, histidine, lysine, ornithine) and acidic amino acids (e.g., aspartic acid, glutamic acid).

The composition of the present invention may also contain other ingredients such as thickeners, stabilizers, pH adjusters, preservatives, UV protection agents, fragrances, and colorants. The specific types and amounts of these ingredients can be set as appropriate.

Examples of thickening agents include carrageenan, dextrin, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, polyacrylic acid, polymethacrylic acid, carboxyvinyl polymer (carbomer), (acrylic acid/alkyl acrylate (C10-30)) copolymer, and xanthan gum.

Examples of stabilizers include ascorbic acid, sodium pyrosulfite, and EDTA.

Examples of pH adjusters include the aqueous solutions (buffer solutions) described above, acidic substances such as hydrochloric acid, and basic substances such as sodium hydroxide.

Preservatives include, for example, ethyl parahydroxybenzoate, sodium benzoate, salicylic acid, sorbic acid, parabens (e.g., methylparaben, propylparaben), and sodium bisulfite.

Examples of UV protection agents include UV absorbers (e.g., t-butyl methoxydibenzoylmethane, ethylhexyl methoxycinnamate, oxybenzone-3) and UV scattering agents (e.g., titanium oxide, zinc oxide).

Fragrances include, for example, limonene, citral, menthol, rose oil, and rose oil.

Examples of pigments include organic pigments (e.g., red pigments such as Red No. 201, blue pigments such as Blue No. 404, orange pigments such as Orange No. 203, yellow pigments such as Yellow No. 205, green pigments such as Green No. 3, organic lake pigments such as zirconium lake, and natural pigments such as chlorophyll), and inorganic pigments (e.g., white pigments such as titanium oxide, colored pigments such as iron oxide, extender pigments such as talc, and pearl pigments such as mica).

The composition of the present invention can be prepared as a composition in any state. Examples of such compositions include liquid compositions, cream compositions, emulsion compositions, powder compositions, stick compositions, and sheet-impregnated compositions. The composition of the present invention is useful as, for example, products such as cosmetics, pharmaceuticals, quasi-drugs, and miscellaneous goods, and as raw materials thereof.

The composition of the present invention can also be used by applying an effective amount (e.g., 1 mg to 100 g) to a desired site (e.g., skin, hair, body hair, scalp) of a subject (e.g., mammals such as humans, animals such as birds and reptiles). Preferably, the composition of the present invention is applied to a human. The condition of the subject to which the composition of the present invention is applied may be one in which the site is in a healthy state, or one in which the site is in an abnormal state (e.g., disease). Examples of such abnormal conditions include rough skin, dry skin, scales, disturbances in turnover, and skin diseases (e.g., dermatitis such as atopic dermatitis).

The composition of the present invention may also contain an effective amount of a compound that induces the expression of genes encoding the various proteins described above that are related to the improvement of stratum corneum function. Such an effective amount is not particularly limited as long as it is an amount that can induce gene expression, but an amount sufficient for inducing gene expression is preferable. Such a sufficient amount may be, for example, a concentration of 0.01 to 1000 mM. From the viewpoint of reducing the amount of compound used, such a sufficient amount may also be 500 mM or less, 100 mM or less, 50 mM or less, 10 mM or less, 5 mM or less, or 1 mM or less.

The composition of the present invention may preferably be a moisturizer. When the composition of the present invention is a moisturizer, the moisturizer of the present invention can exert an excellent effect in preventing, suppressing, or treating conditions such as rough skin through its moisturizing action, and can also exert an anti-wrinkle, anti-spot, or anti-freckle effect.

The composition of the present invention is also a cosmetic or topical preparation. The cosmetic or topical preparation of the present invention can be prepared in any form that can be applied to a desired area (e.g., skin, hair, scalp) in accordance with a conventional method.

The cosmetic or topical preparation of the present invention can be preferably used as a cosmetic or topical preparation for the skin, hair, or scalp. Examples of the cosmetic or topical preparation for the skin include milky lotion, toner, cream, gel, beauty serum, and face mask. Examples of the cosmetic or topical preparation for the hair include hair milky lotion, hair treatment, hair conditioner, shampoo, and hair lotion. Examples of the cosmetic or topical preparation for the scalp include hair growth agents. Examples of preferred cosmetic preparations include leave-on cosmetic preparations, toners, milky lotions, creams, and face masks. Examples of preferred topical preparations include ointments, creams, and mousses.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. All of the N-acyl neutral amino acids used as raw materials in the following production examples are L-form.

Preparation Example A: Synthesis of N-acyl neutral amino acid ester from alcohol and N-acyl neutral amino acid Ethanol (320 mL, 5.48 mol) or isopropyl alcohol (418 mL, 5.48 mol) was added with N-acyl neutral amino acid (0.14 mol) and mixed. p-Toluenesulfonic acid monohydrate (5.3 g, 0.03 mol) was added to the mixture, a reflux tube was attached to prevent the alcohol from evaporating, and the mixture was stirred at a bath temperature of 125°C for 3 hours. The product was concentrated under reduced pressure in vacuum, then diluted with ethyl acetate (600 mL) and washed four times with saturated sodium bicarbonate water (240 mL). The organic phase was further washed twice with ultrapure water (480 mL). Water was removed from the organic layer with sodium sulfate. Furthermore, sodium acid was removed by filtration, and the organic layer was concentrated under reduced pressure in vacuum to obtain the product (acyl neutral amino acid ester).

Production Example 1: Production of N-octanoylalanine isopropyl ester (C8Ala-iPA)

N-octanoylalanine (C8Ala, 30.00 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. C8Val-iPA was obtained (yield 97%) by reacting according to the synthesis method of Example A.

¹ H-NMR (400 MHz, CDCl ₃ , r.t.): δ6.077-6.093 (1H, d, J=6.4Hz), 5.015-5.078 (1H, sep, 6.4Hz), 4.511-4.583 (1H, quint, J = 7.2Hz), 2.184-2.222 (2H, t, J =7.6Hz), 1.599-1.669 (2H, quint, J=7.2Hz), 1.372-1.390 (3H, d, J=7.2Hz) 1.244-1.298 (14H, m), 0.859-0.892 (3H, t, J=6.8Hz) ppm.

ESI-MS (positive) m/z 258.2[M+H] ⁺ ,280.1[M+Na] ⁺

Production Example 2: Production of N-octanoyl valine isopropyl ester (C8Val-iPA)

N-octanoyl valine (C8Val, 34.06 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. The reaction was carried out for 8 hours according to the synthesis method of Example A to obtain C8Val-iPA (yield 93%).

¹ H-NMR (400 MHz, CDCl ₃ , r. .561 (1H, dd), 2.216-2.254 (2H, t, J=7. 2Hz), 2.135-2.182 (1H, sex, J = 6.8Hz), 1.610-1.765 (2H, quint, J = 7.2Hz), 1.256-1.314 (14H , m), 0.860-0.949 (9H, m) ppm.

ESI-MS (positive) m/z 286.2[M+H] ⁺ ,308.1[M+Na] ⁺

Production Example 3: Production of N-octanoylglycine isopropyl ester (C8Gly-iPA)

N-octanoylglycine (C8Gly, 28.18 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. C8Gly-iPA was obtained by reacting according to the synthesis method of Example A (yield 97%).

ESI-MS (positive) m/z 244.1[M+H] ⁺ ,266.1[M+Na] ⁺

Production Example 4: Production of N-octanoyl isoleucine isopropyl ester (C8Ile-iPA)

N-octanoylisoleucine (C8Ile, 36.03 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. C8Ile-iPA was obtained by reacting according to the synthesis method of Example A (yield 71%).

ESI-MS (positive) m/z 300.2[M+H] ⁺ ,322.2[M+Na] ⁺

Production Example 5: Production of N-octanoyl leucine isopropyl ester (C8Leu-iPA)

N-octanoylleucine (C8Leu, 36.03 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C8Leu-iPA (yield 97%).

ESI-MS (positive) m/z 300.2[M+H] ⁺ ,322.2[M+Na] ⁺

Production Example 6: Production of N-lauroyl isoleucine isopropyl ester (C12Ile-iPA)

N-lauroylisoleucine (C12Ile, 43.89 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. C12Ile-iPA was obtained (yield 85%) by reacting according to the synthesis method of Production Example A.

ESI-MS (positive) m/z 356.3 [M+H] ⁺ ,378.2 [M+Na] ⁺

Production Example 7: Production of N-octanoylalanine ethyl ester (C8Ala-Et)

N-octanoylalanine (C8Ala, 30.00 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C8Val-Et (yield 90%).

¹ H-NMR (400 MHz, CDCl ₃ , r. .230 (2H, q, J=7.2Hz), 2.186-2.224 (2H, t, J=7.6Hz), 1.599-1.670 (2H, quint, J=7.2Hz), 1.389-1.407 (3H, d, J=7.2Hz) 1.267- 1.302 (11H, m), 0.860-0.892 (3H, m) ppm.

ESI-MS (positive) m/z 244.2[M+H] ⁺ ,266.1[M+Na] ⁺

Production Example 8: Production of N-octanoyl valine ethyl ester (C8Val-Et)

N-octanoylvaline (C8Val, 34.06 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out for 8 hours according to the synthesis method of Example A to obtain C8Val-Et (yield 93%).

¹ H-NMR (400 MHz, CDCl ₃ , r. ), 2.217-2.255 (2H, t, J=7.2Hz), 2.121-2.202 (1H, sex, J=6.8Hz), 1.610-1.681 (2H, quint, J=7.2Hz), 1.268-1.303 (11H, m) , 0.860-0.952 (9H, m) ppm.

ESI-MS (positive) m/z 272.2[M+H] ⁺ ,294.1[M+Na] ⁺

Production Example 9: Production of N-octanoylglycine ethyl ester (C8Gly-Et)

N-octanoylglycine (C8Gly, 28.18 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C8Gly-Et (yield 96%).

ESI-MS (positive) m/z 230.2[M+H] ⁺ ,252.1[M+Na] ⁺

Production Example 10: Production of N-octanoyl isoleucine ethyl ester (C8Ile-Et)

N-octanoylisoleucine (C8Ile, 36.03 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C8Ile-Et (yield 97%).

ESI-MS (positive) m/z 286.2[M+H] ⁺ ,308.2[M+Na] ⁺

Production Example 11: Production of N-octanoyl leucine ethyl ester (C8Leu-Et)

N-octanoylleucine (C8Leu, 36.03 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C8Gly-Et (yield 98%).

ESI-MS (positive) m/z 286.2[M+H] ⁺ ,308.2[M+Na] ⁺

Production Example 12: Production of N-lauroyl isoleucine ethyl ester (C12Ile-Et)

N-lauroylisoleucine (C12Ile, 43.89 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C12Ile-Et (yield 91%).

ESI-MS (positive) m/z 342.3[M+H] ⁺ ,364.3[M+Na] ⁺

Production Example 13: Production of N-lauroyl leucine ethyl ester (C12Leu-Et)

N-lauroylleucine (C12Leu, 43.89 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C12Leu-Et (yield 88%).

ESI-MS (positive) m/z 342.3[M+H] ⁺ ,364.3[M+Na] ⁺

Production Example 14: Production of N-lauroyl valine ethyl ester (C12Val-Et)

N-lauroylvaline (C12Val, 41.92 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out for 8 hours according to the synthesis method of Example A to obtain C12Val-Et (yield 87%).

ESI-MS (positive) m/z 328.3[M+H] ⁺ ,350.2[M+Na] ⁺

Production Example 15: Production of N-decanoyl valine isopropyl ester (C10Val-iPA)

N-decanoyl valine (C10Val, 38 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. C10Val-iPA was obtained (yield 98%) by reacting according to the synthesis method of Example A.

ESI-MS (positive) m/z 314.5[M+H] ⁺ ,336.4[M+Na] ⁺

Production Example 16: Production of N-decanoylalanine isopropyl ester (C10Ala-iPA)

N-decanoylalanine (C10Ala, 34.6 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C10Ala-iPA (yield 97%).

ESI-MS (positive) m/z 285.4 [M+H] ⁺ , 307.4 [M+Na] ⁺

Production Example 17: Production of N-decanoyl leucine isopropyl ester (C10Leu-iPA)

N-decanoyl leucine (C10Leu, 39.9 g, 0.14 mol) was used as the N-acyl amino acid, and isopropyl alcohol (418 mL, 5.48 mol) was used as the alcohol. The reaction was carried out according to the synthesis method of Example A to obtain C10Leu-iPA (yield 97%).

ESI-MS (positive) m/z 328.5 [M+H] ⁺ , 350.3 [M+Na] ⁺

Production Example 18: Production of N-hexanoyl valine ethyl ester (C6Val-Et)

N-hexanoyl valine (C6Val, 30.14 g, 0.14 mol) was used as the N-acyl amino acid, and ethanol (320 mL, 5.48 mol) was used as the alcohol. The reaction was carried out for 8 hours according to the synthesis method of Example A to obtain C6Val-Et (yield 82%).

ESI-MS (positive) m/z 244.3[M+H] ⁺ ,266.2[M+Na] ⁺

Reference Production Examples 1 to 3: Production of N-lauryl valine isopropyl ester (C12 Val-iPA), N-lauryl alanine isopropyl ester (C12 Ala-iPA), and N-lauryl alanine ethyl ester (C12 Ala-Et) N-lauryl valine isopropyl ester (C12 Val-iPA), N-lauryl alanine isopropyl ester (C12 Ala-iPA), and N-lauryl alanine ethyl ester (C12 Ala-Et) were produced according to the description in JP-A-11-240828.

Example 1: Evaluation of acyl neutral amino acid esters (1) Evaluation of compatibility with hydrophobic organic solvents (oil) 1 g of each sample was weighed out, added to 5 g of liquid paraffin, and mixed by stirring for 10 minutes at 25° C. After stirring was stopped, the mixture was left to stand for 10 minutes at 25° C., and the state of separation of each sample and liquid paraffin was visually confirmed, and evaluation was performed according to the following criteria.
Very favorable (A): No separation was observed, and the solution was clear. Preferred (B): Almost no separation was observed, and the solution was clear. Not very favorable (C): Localized separation occurred, and the solution became cloudy. Completely unfavorable (D): Separation clearly occurred.

(2) Evaluation of compatibility with hydrophilic organic solvent 0.5 g of each sample was weighed out, added to 10 g of 1,3-butylene glycol, and mixed by stirring for 10 minutes at 25° C. After stirring was stopped, the mixture was allowed to stand for 10 minutes at 25° C., and the state of separation of each sample and 1,3-butylene glycol was visually confirmed, and evaluation was performed according to the following criteria.
Very favorable (A): No separation was observed, and the solution was clear. Preferred (B): Almost no separation was observed, and the solution was clear. Not very favorable (C): Localized separation occurred, and the solution became cloudy. Completely unfavorable (D): Separation clearly occurred.

(3) Property Evaluation Each compound was cooled to 4° C. for one day, and then allowed to stand at room temperature (25° C.) for three days. After three days, the properties of each compound were confirmed at room temperature (25° C.).
Preferred (A): The property is liquid at room temperature (25° C.). Therefore, it is easy to prepare a formulation by simply mixing it with other liquid ingredients at room temperature without heating.
Unfavorable (B): The substance is in a solid or crystalline form at room temperature (25° C.), and it is difficult to prepare a formulation by simply mixing it with other liquid ingredients at room temperature without heating.

As a result, the acyl neutral amino acid ester could be stably blended with hydrophobic organic solvents (oils) and hydrophilic organic solvents (Table 1). Therefore, it was demonstrated that the acyl neutral amino acid ester is an excellent oil agent.
The acyl neutral amino acid ester also facilitated the preparation of the formulation (Table 1). Thus, the acyl neutral amino acid ester was shown to have excellent handling properties.

Example 2: Evaluation of hydrolysis of acyl neutral amino acid ester by esterase 5 mg of acyl neutral amino acid ester was added to 1x PBS buffer, and 2.15 μl (0.2 wt%) of Triton-X100 (manufactured by Aldrich) was added, followed by uniform mixing by ultrasonic irradiation. A buffer solution of esterase (Esterase from porcine liver, manufactured by Sigma-Aldrich) was added to the mixture so that esterase was 5 Units per molecule of acyl amino acid, and the mixture was mixed by stirring. This mixture was shaken and stirred for 24 hours in a shaker heated to 30°C to react. The reaction product was centrifuged with a centrifuge at 12000xg, and the supernatant was analyzed by high performance liquid chromatography (manufactured by Shimadzu). As a control, only buffer was added instead of the esterase solution. The esterase used (Esterase from porcine liver) was used as a model of the esterase enzyme present in human skin [Bonina, F. P. et al., Eur. J. Pharm. Sci. 14, 123-134 (2001); Wong, O. et al., Int. J. Pharm., 52, 191-202 (1989); Vavrova K. et al., J. Control Release. 104, 41-49 (2005)].

When the ester bond of the acyl neutral amino acid ester is hydrolyzed by esterase, the peak area of the acyl neutral amino acid ester decreases on the HPLC chromatogram, and a new peak is observed at the same elution time as the acyl neutral amino acid. The appearance of this peak allows us to conclude that the acyl neutral amino acid ester has been hydrolyzed by esterase to produce the acyl neutral amino acid.

The test substances used were the compounds produced in Production Examples 1 to 18 and Reference Production Examples 1 to 3.

In the presence of esterase, C6Val-Et, C8Ala-iPA, C8Val-iPA, C8Gly-iPA, C8Ile-iPA, C8Leu-iPA, C8Ala-Et, C8Val-Et, C8Gly-Et, C8Ile-Et, C8Leu-Et, C12Ile-Et, C10Ala-iPA, C10Val-iPA, C10Leu-iPA, C12 All of Ala-Et, C12Ala-iPA, C12Val-Et, C12Val-iPA, C12Ile-iPA, and C12Leu-Et were hydrolyzed to produce C6VAl, C8Ala, C8Val, C8Gly, C8Ile, C8Leu, C10Ala, C10Val, C10Leu, C12Ala, C12Val, C12Ile, and C12Leu.

Examples 3 to 7 and Comparative Examples 2 to 3: Comparison of amplification amount of genes of moisturizing-related proteins, etc. by octanoyl neutral amino acids Human normal epidermal keratinocytes NHEK (NB) (Kurabo Industries, Ltd.) were pre-cultured in HuMedia-KG2 (Kurabo Industries, Ltd.) and adjusted to a concentration of 30 x ¹⁰⁴ cells/mL, and 2 mL of the adjusted culture solution (i.e., 60 x ¹⁰⁴ cells/well) was added to a 6-well plate and cultured at 37°C for 1 day. Samples (octanoyl valine (Example 3: C8Val), octanoyl alanine (Example 4: C8Ala), octanoyl leucine (Example 5: C8Leu), octanoyl isoleucine (Example 6: C8Ile), octanoyl glycine (Example 7: C8Gly), glycylproline (Comparative Example 2: Gly-Pro), and valine (Comparative Example 3: Val)) were added to the concentrations shown in each figure and reacted for 48 hours. After the reaction, total RNA was extracted from the cells, reverse transcribed, and the amount of amplification of target genes (filaggrin, involucrin, transglutaminase (TG) 1, keratin 10, and loricrin) was measured by real-time PCR (n=2), and compared with the amount of amplification of the control (no addition). GAPDH was used as a correction gene. The calculation was performed using the comparative CT method, the primers and probes used were TaqMan® Gene Expression, and the fluorescent dye used was FAM. The results are shown in Figures 1 and 2.

As is clear from Figures 1 and 2, the amount of amplification of each target gene in Examples 3 to 7 was higher than in Comparative Examples 2 and 3. These results indicate that acyl neutral amino acids can promote the production of moisturizing-related proteins.

Examples 8 to 13: Comparison of amplification amount of genes such as moisturizing-related proteins by acyl valine The same procedure as in Example 3 was carried out except that butanoyl valine (Example 8: C4Val), hexanoyl valine (Example 9: C6Val), octanoyl valine (Example 10: C8Val), decanoyl valine (Example 11: C10Val), lauroyl valine (Example 12: C12Val) and acetyl valine (Example 13: C2Val) were used as samples and that filaggrin, involucrin, and transglutaminase (TG) 1 were used as target genes. The results are shown in FIG. 3.

As is clear from Figure 3, the amount of amplification of each target gene was higher in all of Examples 8 to 13 compared to the control. These results indicate that acyl neutral amino acids or salts thereof having an acyl group with 2 to 12 carbon atoms can promote the production of moisturizing-related proteins regardless of the type of acyl group.

Examples 14 to 24: Comparison of the amount of filaggrin gene amplification by acyl valine or acylalanine Human normal epidermal keratinocytes NHEK (NB) (Kurabo Industries, Ltd.) were pre-cultured in HuMedia-KG2 (Kurabo Industries, Ltd.) and adjusted to a concentration of 15 x ¹⁰⁴ cells/mL, and 2 mL of the adjusted culture solution (i.e., 30 x ¹⁰⁴ cells/well) was added to a 6-well plate and cultured at 37°C for 1 day. Samples (lauroyl valine (Example 14: C12Val), decanoyl valine (Example 15: C10Val), octanoyl valine (Example 16: C8Val), hexanoyl valine (Example 17: C6Val), butanoyl valine (Example 18: C4Val), acetyl valine (Example 19: C2Val), lauroyl alanine (Example 20: C12Ala), decanoyl alanine (Example 21: C10Ala), octanoyl alanine (Example 22: C8Ala), hexanoyl alanine (Example 23: C6Ala), butanoyl alanine (Example 24: C4Ala)) were added to the concentrations shown in each figure and reacted for 24 hours. After the reaction, total RNA was extracted from the cells, reverse transcription was performed, and the amount of amplification of the target gene (filaggrin) was measured by real-time PCR (n=2), and the amount of amplification of the control (no addition) was set to 100% and compared with this value. GAPDH was used as a correction gene. Calculation was performed using the comparative CT method, the primers and probes were TaqMan (registered trademark) Gene Expression, and the fluorescent dye was FAM.

The following evaluations were performed according to the amount of amplification. The results are shown in Tables 2 and 3 and Figures 4 and 5.
Very favorable (A): 200% or more. Preferred (B): 100% or more but less than 200%. Not very favorable (C): 50% or more but less than 100%. Not favorable at all (D): Less than 50%.

Considering the results of Examples 2 to 24 above (Tables 1 and 2, Figures 1 to 5), it is believed that the acyl neutral amino acid ester can improve the expression of moisturizing-related proteins, and therefore can improve the moisturizing ability of the skin to retain moisture inside the stratum corneum. Furthermore, considering these results as well as the results of Example 1, it is believed that the acyl neutral amino acid ester can improve moisture retention in the skin by both its action inside the stratum corneum and its emollient action, which prevents moisture loss from the skin and retains moisture.

Examples 25 to 31: Comparison of cytotoxicity between acyl valine and acyl valine ester Human normal epidermal keratinocytes NHEK (NB) (Kurabo Industries, Ltd.) were pre-cultured in HuMedia-KG2 (Kurabo Industries, Ltd.) to adjust the concentration to 15 x ¹⁰⁴ cells/mL, and 2 mL of the adjusted culture solution (i.e., 30 x ¹⁰⁴ cells/well) was added to a 6-well plate and cultured at 37°C for 1 day. Samples (lauroyl valine (Comparative Example 4: C12Val), decanoyl valine (Example 25: C10Val), octanoyl valine (Example 26: C8Val), hexanoyl valine (Example 27: C6Val), butanoyl valine (Example 28: C4Val), acetyl valine (Example 29: C2Val), lauroyl valine-iPA (Example 30: C12Val-iPA), lauroyl valine-Et (Example 31: C12Val-Et) were added to the concentrations shown in each figure and reacted for 24 hours. Thereafter, the medium was discarded and replaced with 2 mL/well of Neutral Red solution, and further cultured for 2 hours. The Neutral Red solution was Neutral Red. Neutral Red (Kurabo) was diluted 1/100 with a mixture of HuMedia-KG2 medium and physiological saline (2:1) for use. Cells stained with Neutral Red were washed once with PBS(-), fixed with 1% _CaCl2 /1% formalin solution (1.5 mL/well) for 1 minute, extracted with 1% acetic acid/50% ethanol solution (1.5 mL/well) for 20 minutes at room temperature, and absorbance at 540/630 nm was measured using a plate reader.

The following evaluations were performed according to the cell viability, and the results are shown in Table 4 and FIG.
Very favorable (A): 95% or more. Preferred (B): 75% or more but less than 95%. Not very favorable (C): 50% or more but less than 75%. Not favorable at all (D): Less than 50%.

The results of Examples 14 to 24 show that each acyl neutral amino acid can amplify the filaggrin gene. Furthermore, the results of Examples 25 to 31 and Comparative Example 4 show that the acyl neutral amino acids and acyl neutral amino acid esters of Examples 25 to 31 have low cytotoxicity, whereas the acyl neutral amino acid of Comparative Example 4 has high cytotoxicity. Interestingly, unlike N-acyl amino acid esters with long acyl chains, no cytotoxicity was observed. Summarizing the above evaluations of cytotoxicity, it can be seen that acyl neutral amino acid esters are more preferable than acyl neutral amino acids.

Example 32: Compatibility test of acyl neutral amino acid ester and hydrophilic organic solvent The components shown in Table 5 were weighed into a 1.5 mL Eppendorf tube, and the mixture was stirred uniformly by stirring with a vortex mixer (Scientific Industries Vortex Genie 2) and by shaking the sample up and down vigorously by hand, and the state after stirring was visually observed. The evaluation criteria were A for a uniform, transparent solution, and B for one in which oil droplets were dispersed and scattered light was observed. The evaluation was performed under conditions of storage at 25°C, -5°C, and 45°C for one day.

As a result, the acyl neutral amino acid ester had high solubility stability in hydrophilic organic solvents within the effective concentration range (Tables 5-1 and 5-2). This shows that the acyl neutral amino acid ester can be stably blended with hydrophilic organic solvents within the effective concentration range without the use of an emulsifier.

Example 33: Test for improving compatibility between acyl neutral amino acid ester and hydrophilic organic solvent Evaluation was performed using the samples used in the compatibility test above (Table 6). Using a poly dropper, one drop of the sample was dropped onto a slide glass, and the spread of the sample after standing for 5 minutes was measured using a ruler. The greater the spread of the sample, the easier it is to blend when applied, which is preferable for practical use. The measured value of the polyhydric alcohol to which the acyl neutral amino acid ester or oil was added was designated a, and the measured value of the polyhydric alcohol alone was designated b, and the spread degree was evaluated according to the following formula. The spread degree was evaluated in four stages.

Spreading degree: (a/b) x 100
A: 150% or more B: 130% or more but less than 150% C: 100% or more but less than 130% D: Less than 100%

As a result, the acyl neutral amino acid ester was able to improve compatibility with hydrophilic organic solvents (Table 6). Therefore, it was shown that the acyl neutral amino acid ester, when combined with a hydrophilic organic solvent, can improve the wettability of the formulation and improve compatibility with the skin.

Example 34: Improvement of profilaggrin production rate by octanoyl valine (C8Val) First, human normal epidermal keratinocytes NHEK (NB) (Kurabo Industries, Ltd.) were cultured in HuMedia-KG2 (Kurabo Industries, Ltd.) at 37°C, 5% CO2, and saturated water vapor. The confluent cells were seeded in a 6-well plate at 15 x ¹⁰⁴ (cells/well). After culturing at 37°C for 1 day, the medium was replaced with HuMedia-KG2 medium supplemented with 100 μM octanoyl valine (C8Val) and 1.3 mM _CaCl2 , and the medium was replaced in the same manner every 1 to 2 days, and the culture was continued for 6 days. After culturing, the medium was removed, the wells were washed twice with cold PBS (-), and 200 μL/well of extract (M-PER (Thermo Fisher Scientific)) containing protease inhibitor and phosphatase inhibitor (EzRIPA Lysis (ATTO)) was added to each well, and the wells were shaken at 200 rpm for 5 minutes in a shaker (TAITEC). The cells were scraped with a scraper, and 200 μL of a denaturant (EzApply (ATTO)) was added to the total amount of liquid including the precipitate, and the wells were heated and shaken at 1100 rpm and 100 ° C. for 5 minutes in a shaker (Bioer Technology). The resulting solution was centrifuged at 10,000 G in a centrifuge (manufactured by Tommy Seiko Co., Ltd.) at 4° C. for 10 minutes, and the supernatant was used as a sample for Western blotting.

Next, 20 μL of each Western blot sample (profilaggrin) or 5 μL of a 50-fold diluted solution of the Western blot sample prepared in (1) (GAPDH) was applied to an e-PAGEL 7.5% (ATTO) per gel lane, and electrophoresis was performed for 1 hour at a constant current of 21 mA in an electrophoresis device (ATTO). After electrophoresis, the gel was transferred to a PVDF membrane, washed with TBS-T (ATTO), and blocked with EzBlock BSA (ATTO). Next, an antigen-antibody reaction was carried out using a primary antibody solution (Anti Filaggrin (AKH1) antibody (manufactured by Santa Cruz Biotechnology) (profilaggrin), Anti GAPDH (6C5) antibody (manufactured by Santa Cruz Biotechnology) (GAPDH)). Labeling was performed with a secondary antibody (Anti-IgG (H+L), Mouse, Goat-poly, HRP (manufactured by KPL)), and the band intensity (250-400 kDa (profilaggrin), 37 kDa (GAPDH)) was quantified using an image analyzer (manufactured by Amersham) by the chemiluminescence method (n=2). The expression level of profilaggrin was normalized by the expression level of GAPDH, and the production level of the control (no addition of octaenoylvaline (C8Val)) was set as 100% for comparison.

The results obtained were evaluated as follows and are shown in Table 7.
Very favorable (A): 250% or more. Preferred (B): 150% or more but less than 250%. Not very favorable (C): 100% or more but less than 150%. Not favorable at all (D): Less than 100%.

From the above, it was revealed that octanoylvaline (C8Val) improves the production of profilaggrin protein.

Example 35: Evaluation of partition coefficient of acyl neutral amino acid ester The partition coefficient (LogP) of acyl neutral amino acid ester was calculated using a chemical structural formula calculation software called ChemSketch (manufactured by Advanced Chemistry Development, Inc. (ACD/Labs)).

From Table 8, it can be seen that the LogP values of acyl neutral amino acid esters such as C6Ala-iPA, C6Val-Et, and C6Ile-Et are in the range of 1 to 4, and have superior properties for transdermal absorption (Marc Schneider, M. et al., Dermatoendocrinol., 1, 197-206 (2009)).

The composition of the present invention is useful, for example, as a cosmetic preparation such as a leave-on cosmetic preparation, a topical preparation, and as a raw material thereof.

Claims (4)

An agent for enhancing the expression of a gene encoding a protein that may be involved in skin barrier function, comprising N-octanoyl valine ethyl ester,
An expression enhancer, wherein the protein that may be involved in skin barrier function is selected from the group consisting of filaggrin, involucrin, transglutaminase 1, keratin 10, and loricrin. An agent for enhancing the expression of a gene encoding a protein that may be involved in skin barrier function, comprising N-octanoylalanine ethyl ester,
An expression enhancer, wherein the protein that may be involved in skin barrier function is selected from the group consisting of filaggrin, involucrin, transglutaminase 1, keratin 10, and loricrin. An agent for enhancing the expression of a gene encoding filaggrin, comprising N-octanoyl isoleucine ethyl ester. An agent for enhancing the expression of a gene encoding a protein that may be involved in skin barrier function, comprising N-octanoylglycine ethyl ester,
An expression enhancer, wherein the protein that may be involved in skin barrier function is selected from the group consisting of involucrin, transglutaminase 1, keratin 10, and loricrin.

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