TRPA1 expression inhibitor and composition containing the same

Abstract

The objective is to provide a technology that suppresses TRPA1 expression. [Solution] TRPA1 expression is suppressed using a specific plant. One or more substances selected from the group consisting of clove extract and evening primrose extract are used as the active ingredient of the TRPA1 expression inhibitor.

Description

[Technical Field]

[0001] The present invention relates to a TRPA1 expression inhibitor and a composition containing the same. [Background technology]

[0002] The darkening of the skin after sun exposure is classified into three types: immediate darkening, persistent immediate darkening, and delayed darkening. Immediate darkening is a dull grayish-brown pigmentation caused by UVA radiation, and generally disappears within a few hours after exposure. In delayed darkening, inflammation occurs due to UV radiation, and the darkening peaks 3 to 10 days later as the inflammation subsides, with the pigmentation sometimes lasting for several months or more. Persistent immediate melanosis is a brownish skin darkening that occurs after immediate melanosis subsides. Unlike immediate melanosis, which is a reversible color change, it is an irreversible pigmentation that is thought to disappear with epidermal turnover. One known cause of persistent immediate melanosis is that melanocytes sense ultraviolet light, which promotes melanin production. Specifically, melanocytes contain a photoreceptor protein called rhodopsin, and when this protein senses UVA, it promotes the influx of calcium ions into the cell via PLC, leading to melanin production within a few hours (Non-Patent Literature 1).

[0003] On the other hand, members of the transient receptor potential (TRP) family Transient receptor potential ankyrin 1 (also known as TRPA1) is a non-selective cation channel with high permeability to calcium, sodium, and potassium ions, and is widely distributed in various parts of the human body. Calcium ion influx via TRPA1 is involved in various biological processes (Non-Patent Literature 2). It has been reported that increased intracellular calcium ion influx activates TRPA1 (Non-Patent Literature 3, 4). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Wicks NL et al., Current Biology, 2011, 21(22), 1906-1911 [Non-Patent Document 2] Hu F. et al., Experimental and Therapeutic Medicine, 2021, 22, 1462 [Non-Patent Document 3] Doerner, JF et al., Journal of Biological Chemistry, 2007, 282(18), 13180-13189 [Non-Patent Document 4] Zurborg, S. et al., Nature neuroscience, 2007, 10, 277-279 [Overview of the project] [Problems that the invention aims to solve]

[0005] Based on the aforementioned report, it is hypothesized that when TRPA1, a channel that permeates calcium ions, is activated, the influx of calcium ions into cells is promoted, leading to melanin production. Therefore, suppressing TRPA1 expression is expected to suppress melanin production, and consequently, to produce a skin-whitening effect.

[0006] In this context, the present invention aims to provide a technology for suppressing TRPA1 expression. [Means for solving the problem]

[0007] The inventors conducted diligent research to solve the above problems and, as a result, discovered a plant extract that has TRPA1 expression inhibitory activity, thus completing the present invention. Furthermore, the inventors found that in serum... We found that low sodium ion concentrations can increase TRPA1 expression in melanocytes. Furthermore, we found that plant extracts with TRPA1 expression inhibitory effects can also have TRPA1 expression inhibitory effects when serum sodium ion concentrations are low.

[0008] In other words, the present invention is as follows: [1] A TRPA1 (transient receptor potential ankyrin 1) expression inhibitor containing the following component (a) as the active ingredient: (a) One or more selected from the group consisting of clove extract (Syzygium aromaticum) and evening primrose extract (Oenothera biennis). [2] Furthermore, the TRPA1 expression inhibitor described in [1] contains the following component (b): (b) One or more selected from the group consisting of soybean (Glycine max) extract, meadowsweet (Filipendula ulmaria) extract, wild rose (Rosa canina) extract, cornflower (Centaurea cyanus) extract, and horse chestnut (Aesculus hippocastanum) extract. [3] A TRPA1 expression inhibitor according to [1] or [2], which suppresses TRPA1 expression in subjects whose serum sodium ion concentration is 150 mM or less. [4] The TRPA1 expression inhibitor according to [3], wherein the subject is one or more subjects selected from the group consisting of pregnant, obese, and elderly. [5] A TRPA1 expression inhibitor described in any of [1] to [4] for use during the summer. [6] A TRPA1 expression inhibitor according to any one of [1] to [5], which suppresses the expression of TRPA1 in melanocytes. [7] A composition for inhibiting TRPA1 expression, comprising a TRPA1 expression inhibitor described in any of [1] to [6]. [8] A composition for whitening, containing a TRPA1 expression inhibitor according to any one of [1] to [6]. [9] The composition according to [7] or [8], which is a composition for external use on the skin.

[10] The composition according to any one of [7] to [9], which is a cosmetic. [Effects of the Invention]

[0009] According to the present invention, a component that suppresses the expression of TRPA1 is provided. In particular, a component that suppresses the expression of TRPA1 and is suitable for use under low sodium ion concentration conditions is provided. [Brief Description of the Drawings]

[0010] [Figure 1] A graph showing the mRNA expression level of the TRPA1 gene in melanocytes cultured under conditions of sodium ion concentration of 130 mM, 140 mM, 150 mM, or 160 mM. [Figure 2] A graph showing the mRNA expression level of the TRPA1 gene in melanocytes when cultured with the addition of clove extract. [Figure 3] A graph showing the mRNA expression level of the TRPA1 gene in melanocytes when cultured with the addition of Portulaca oleracea extract. [Figure 4] A graph showing the mRNA expression level of the TRPA1 gene in melanocytes when cultured with the addition of clove extract and peony extract. [Figure 5] A graph showing the mRNA expression level of the TRPA1 gene in melanocytes when cultured with the addition of clove extract and Galium boreale extract. [Figure 6] A graph showing the mRNA expression level of the TRPA1 gene in melanocytes when cultured with the addition of clove extract and Portulaca oleracea extract. [Figure 7]A graph showing the mRNA expression levels of the TRPA1 gene in melanocytes cultured with clove extract and soybean extract. [Figure 8] A graph showing the mRNA expression levels of the TRPA1 gene in melanocytes cultured with clove extract and cornflower extract. [Figure 9] A graph showing the mRNA expression levels of the TRPA1 gene in melanocytes cultured with the addition of evening primrose extract and horse chestnut extract. [Modes for carrying out the invention]

[0011] <1> TRPA1 expression inhibitor The TRPA1 expression inhibitor of the present invention (also referred to as "the agent of the present invention") comprises the following component (a) as an active ingredient: (a) One or more selected from the group consisting of clove extract (Syzygium aromaticum) and evening primrose extract (Oenothera biennis).

[0012] The agent of the present invention may further contain the following component (b): (b) One or more selected from the group consisting of soybean (Glycine max) extract, meadowsweet (Filipendula ulmaria) extract, wild rose (Rosa canina) extract, cornflower (Centaurea cyanus) extract, and horse chestnut (Aesculus hippocastanum) extract.

[0013] Wild rose (Rosa canina) is also known as canine rose or dog rose. The horse chestnut tree (Aesculus hippocastanum) is also known as the European horse chestnut.

[0014] In this invention, components (a) and (b) are collectively referred to as "plant extract." Plant extract refers not only to the extract itself derived from the plant, but also to fractions of the extract, purified fractions, and solvent-removed products of the extract or fraction or purified product.

[0015] Furthermore, any plant-derived extract that is commonly used in topical skin preparations such as cosmetics and pharmaceuticals, or in orally ingested compositions, can be used, and extracts obtained from plants by conventional methods can be used. For extraction, the entire plant may be used, or parts such as the plant body, above-ground parts, rhizomes, trunks, leaves, stems, flowers, flower buds, fruits, peels, seeds, and roots may be used in the extraction process. Preferred extraction parts include flower buds for clove extract, seeds for evening primrose, seeds for soybean extract, flowers for meadowsweet extract, fruits for rosehip extract, flowers for cornflower extract, and fruits, leaves, and / or bark for horse chestnut extract.

[0016] As the extraction solvent, one or more polar solvents selected from water, alcohols such as ethanol, isopropyl alcohol, and butanol; polyhydric alcohols such as 1,3-butylene glycol and polypropylene glycol; ketones such as acetone and methyl ethyl ketone; and ethers such as diethyl ether and tetrahydrofuran are preferably used.

[0017] Specific extraction methods include, for example, adding 1 to 30 parts by mass of solvent to 1 part by mass of the plant body or its dried product to be used for extraction, immersing it for several days at room temperature or for several hours at a temperature near its boiling point, cooling it to room temperature, removing insoluble matter and / or solvent as desired, and then fractionating and purifying it by column chromatography or the like.

[0018] The total content of component (a) in the agent of the present invention is preferably 0.00001 to 0.09% by mass, more preferably 0.00005 to 0.05% by mass, and even more preferably 0.0001 to 0.003% by mass, on a solid basis. Furthermore, the total content of component (b) in the agent of the present invention is preferably 0.00001 to 0.09% by mass, more preferably 0.00005 to 0.05% by mass, and even more preferably 0.0001 to 0.003% by mass, on a solid basis. By setting the content within the above range, the desired effect can be easily obtained, and flexibility in formulation design can be ensured. The above-mentioned content can be appropriately adjusted according to the administration route and the form of the composition to be contained, as described later.

[0019] Both clove extract and evening primrose extract have the effect of suppressing the expression of the TRPA1 gene. In other words, these extracts are active ingredients in TRPA1 expression inhibitors. Specifically, clove extract and evening primrose extract each have the effect of suppressing the expression of the TRPA1 gene in melanocytes.

[0020] Furthermore, soybean extract, meadowsweet extract, rosehip extract, cornflower extract, and horse chestnut extract all have the effect of suppressing the expression of the TRPA1 gene. In other words, each of these extracts is an active ingredient in TRPA1 expression inhibitors. Specifically, soybean extract, meadowsweet extract, rosehip extract, cornflower extract, and horse chestnut extract each have the effect of suppressing the expression of the TRPA1 gene in melanocytes.

[0021] The suppression of TRPA1 expression can be confirmed by the fact that the TRPA1 expression level in cells to which the target substance has been added is lower than that in cells to which the substance has not been added, usually 90% or less, preferably 80% or less, and more preferably 70% or less. The TRPA1 expression level can be determined, for example, by performing PCR using a DNA fragment having a sequence that specifically binds to the TRPA1 gene sequence as a primer and measuring the amount of mRNA. Alternatively, for example, the intracellular abundance of the protein encoded by the TRPA1 gene may be quantitatively measured by a conventional method and used as the TRPA1 expression level.

[0022] As mentioned above, it is hypothesized that when TRPA1, a channel that permeates calcium ions, is activated, the influx of calcium ions is promoted, leading to melanin production. Therefore, suppressing the expression of TRPA1 in melanocytes is thought to lead to the suppression of melanin production, and consequently to a skin whitening effect. Accordingly, the agent of the present invention may be used for skin whitening. In the present invention, "skin whitening" includes suppressing melanin production, suppressing pigmentation in the skin, and suppressing skin darkening. The agent of the present invention may be used in particular to inhibit melanin production, or in particular to inhibit persistent immediate blackening. In this invention, "persistent immediate blackening" refers to blackening that does not disappear even 24 hours or more after ultraviolet irradiation, and is distinguished from "immediate blackening," which blackens immediately after ultraviolet irradiation and disappears within a few minutes to a few hours after irradiation.

[0023] The agents of the present invention can be applied to mammals such as humans. While the subjects to which the agents of the present invention can be applied are not particularly limited, it is preferable that the subjects have a serum sodium ion concentration of 150 mM or less. A low serum sodium ion concentration, for example, 150 mM When the sodium ion concentration in serum is below mM, TRPA1 expression in melanocytes may increase. The agent of the present invention has the effect of suppressing TRPA1 expression even at low concentrations of sodium ions in serum. The sodium ion concentration in the serum of the subject may be 160 mM or less, 155 mM or less, 150 mM or less, 145 mM or less, 140 mM or less, 135 mM or less, or 130 mM or less, or 120 mM or more, 125 mM or more, 130 mM or more, 135 mM or more, or 140 mM or more, and any non-contradictory combination of these may be used. Specifically, for example, the sodium ion concentration in the serum of the subject may be 120 mM to 160 mM, 125 mM to 155 mM, 130 mM to 150 mM, 135 mM to 145 mM, 140 mM to 160 mM, 120 mM to 140 mM, 125 mM to 135 mM, or 120 mM to 130 mM. The sodium ion concentration in serum can be measured using a known analytical instrument such as the Cobas® 6000 (Roche Diagnostics K.K.).

[0024] Examples of subjects with serum sodium ion concentrations of 150 mM or less include one or more subjects selected from groups consisting of pregnant women, obese individuals, and elderly individuals. TRPA1 expression in melanocytes may increase when serum sodium ion concentrations are low, for example, in pregnant women, obese individuals, and elderly individuals. The agent of the present invention has the effect of suppressing TRPA1 expression even in such cases.

[0025] The target group for the study can be pregnant women at any stage of pregnancy: early pregnancy (up to 14 weeks), mid-pregnancy (15 to 28 weeks), or late pregnancy (29 weeks and beyond). The sodium ion concentration in the serum of pregnant women follows a pattern of being lowest in early pregnancy and gradually increasing towards the end of pregnancy. Furthermore, it is known that the serum sodium ion level throughout pregnancy remains around 138 mM (Masao Nakabayashi, Japan Society of Obstetrics and Gynecology website, Obstetrics and Gynecology Hour, "Water and Electrolyte Metabolism in Pregnancy-Induced Toxemia," March 16, 1998, Internet).<URL:https: / / www.jaog.or.jp / sep2012 / JAPANESE / MEMBERS / TANPA / H10 / 980316.html> )

[0026] Obesity refers to individuals with a BMI of 25 or higher. The BMI may be 25 or higher, 30 or higher, or 35 or higher, or 45 or lower, 40 or lower, or 35 or lower, and any non-contradictory combination of these may also be permitted. Specifically, the BMI may be between 25 and 45, 30 and 40, 35 and 40, or 30 and 35. The mean serum sodium ion concentration in obese patients is 138.3 mM, which is known to be significantly lower than after weight loss (Anne-Lise Bjorke-Monsen et al., Clinical Nutrition ESPEN, 2021, 41, 405-411).

[0027] The term "elderly" refers to individuals aged 65 or older. This age range can be 65 or older, 70 or older, 75 or older, 80 or older, 85 or older, or 100 or younger, 95 or younger, 90 or younger, 85 or younger, or any non-contradictory combination of these ages. Specifically, the age ranges could be 65-100, 70-95, 75-90, 80-85, or 85-90. It is known that in the elderly group aged 65 and over, the proportion of individuals with serum sodium ion concentrations below 135 mM is significantly higher compared to adults under 65 years of age (Mauro Giordano MD et al., The American Journal of Emergency Medicine, 2017, 35(5), 749-752).

[0028] Furthermore, while there are no particular limitations on the timing of use of the agent of the present invention, it is preferable that the agent of the present invention be used in the summer. Here, "summer" refers to June to September. TRPA1 expression in melanocytes occurs in the summer when serum sodium ion concentration is low. While it may increase, the agent of the present invention also has the effect of suppressing TRPA1 expression even in summer. The sodium ion concentration in the serum of healthy individuals fluctuates annually within a range of approximately 128 to 168 mM, and several studies have reported that the concentration is lower in summer (June to September) than in winter (December to March) (Morimoto T. et al., The Japanese journal of physiology, 1969, 19, 801-813; Yoshimura, H., The Japanese journal of physiology, 1958, 8, 165-179; Kobayashi, Hiroko, Tokyo Women's Medical University Journal, 1956, 26, 591-623). [Fluctuation rate of serum sodium ion concentration] While this varies depending on the report, for example, the aforementioned literature by Hiroko Kobayashi reports that the average serum sodium ion concentration of 24 Japanese men and women was highest in February and March at approximately 157 mM, and lowest in July at approximately 135 mM. Furthermore, the aforementioned literature by Morimoto T. et al. reports that the average serum sodium ion concentration of 30 Japanese men was approximately 140 mM in February-March and approximately 130 mM in August-September.

[0029] The agent of the present invention may be used at temperatures of 15°C or higher, 20°C or higher, 25°C or higher, or 30°C or higher, or at room temperature, or at temperatures of 45°C or lower, 40°C or lower, or 35°C or lower, or in combination thereof. Specifically, for example, it may be used at temperatures of 15°C to 45°C, 20°C to 40°C, 25°C to 35°C, or 30°C to 45°C.

[0030] The administration route of the agent of the present invention is not particularly limited and can be transdermal, oral, nasal, intravenous injection, etc., but transdermal administration is preferred. Here, "administration" may be replaced with "ingestion". The dosage is not particularly limited, but considering the desired effect and safety, it is preferable to take 0.3 to 300 μg / day of component (a) in terms of solid matter, in one dose or divided into several doses. In addition to single doses, it is also preferable to take it continuously or intermittently for several weeks to several months.

[0031] A composition containing the agent of the present invention may be a whitening composition, a melanin production inhibitory composition, or a long-lasting immediate darkening inhibitory composition.

[0032] When the agent of the present invention is administered transdermally, it is preferable to use it as a topical skin composition. The form of the topical skin composition is not particularly limited as long as it is applied topically to the skin, but cosmetics (including quasi-drugs) and pharmaceuticals are preferred, with cosmetics being more preferred. The areas to which the topical skin composition is applied are not particularly limited, but are usually the face, limbs, neck, and décolleté.

[0033] Examples of dosage forms for topical skin compositions include, but are not limited to, lotions, emulsifiers such as emulsions and creams, oils, gels, packs, and cleansers. Furthermore, the composition for topical application to the skin may be either a leave-on type or a leave-off type.

[0034] When the composition of the present invention is in the form of a topical skin composition, during its manufacture, ingredients commonly used in the formulation of cosmetics, quasi-drugs, pharmaceuticals, etc., may be arbitrarily incorporated. Such optional components include, for example, hydrocarbons such as squalane, petrolatum, and microcrystalline wax; esters such as jojoba oil, carnauba wax, and octyldodecyl oleate; triglycerides such as olive oil, beef tallow, and coconut oil; fatty acids such as stearic acid, oleic acid, and retinoic acid; higher alcohols such as oleyl alcohol, stearyl alcohol, and octyldodecanol; anionic surfactants such as sulfosuccinates and sodium polyoxyethylene alkyl sulfate; and amphoteric surfactants such as alkyl betaine salts. The following can be optionally added: fermentation agents, cationic surfactants such as dialkylammonium salts, sorbitan fatty acid esters, fatty acid monoglycerides, polyoxyethylene adducts thereof, polyoxyethylene alkyl ethers, nonionic surfactants such as polyoxyethylene fatty acid esters, polyethylene glycol, glycerin, polyhydric alcohols such as 1,3-butanediol, thickeners / gelling agents, antioxidants, UV absorbers, colorants, preservatives, powders, etc. In addition, plant extracts other than components (a) and (b) can be optionally added. [Examples]

[0035] 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 unless it exceeds the essence of the invention.

[0036] <Test Example 1> Relationship between sodium ion concentration and TRPA1 expression level The inventors of this invention tested the relationship between sodium ion concentration and TRPA1 gene expression level using the following procedure. Normal human epidermal melanocytes (HEM-d: Human Epidermal Melanocytes-dark, neonatal, male) Sex, Darkly pigmented, Kurabo Industries Ltd.) 6 x 10 in a 24-well plate 4 Cells were seeded per well and cultured overnight at 37°C in a 5% CO2 environment. The culture medium used was Medium 254 (Thermo Fisher Scientific Corporation, Gibco). TM , M254500) HMGS special Injection Growth Additive Set (7.5 ml per 500 ml of Medium 254) (Kurabo Industries Ltd.) Manufactured by Thermo Fisher Scientific (KM-6350) and an antibiotic-antifungal agent (100x) Gibco Co., Ltd. TM A mixture containing (15240-062) was used.

[0037] After culturing, remove the culture medium, wash the cells once with Dulbecco's PBS(-) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 041-20211), and add 1 ml / c of ​​each of the following media with different sodium ion concentrations. After adding gel, the cells were cultured for 72 hours under conditions of 37°C and 5% CO2. <culture medium> As the culture medium, Humedia-KB2 (Kurabo Industries Ltd., KK-2350S) is mixed with HMGS custom growth additive. (7.5 ml per 500 ml of Humedia-KB2) (manufactured by Kurabo Industries Ltd., KM-6350) and antibiotic-antifungal agent (100 x) (Thermo Fisher Scientific K.K., Gibco) TM A mixture containing sodium iodine (15240-062) was used. In addition, Humedia-KB2 was used with sodium iodine. Since it contains approximately 130 mM of sodium ions, the culture medium was used as a "culture medium with a sodium ion concentration of 130 mM." Furthermore, assuming a sodium ion concentration of 130 mM in the culture medium, 5 M NaCl was added to the culture medium so that the final sodium ion concentrations were 140 mM, 150 mM, and 160 mM, respectively. These were then used as "culture medium with a sodium ion concentration of 140 mM," "culture medium with a sodium ion concentration of 150 mM," and "culture medium with a sodium ion concentration of 160 mM," respectively.

[0038] After culturing, the cells were harvested and RNA was extracted using a standard method. cDNA was synthesized from the extracted RNA using a standard method, and PowerTrack TM SYBR Green Master Mix for qPCR (Thermo Fisher Science) TIFIC Corporation, Applied Biosystems TM Using A46111), the RT-qPCR method was used to determine the TR The expression levels of each PA1 gene were analyzed. The GAPDH gene was used as an endogenous control.

[0039] Figure 1 shows the mRNA expression levels of the TRPA1 gene in groups cultured in 130 mM sodium ion medium, 140 mM sodium ion medium, 150 mM sodium ion medium, and 160 mM sodium ion medium, as relative values ​​with the mRNA expression level in the group cultured in 130 mM sodium ion medium set to 1.

[0040] As shown in Figure 1, the mRNA expression level of the TRPA1 gene decreased in a manner dependent on the sodium ion concentration of the culture medium. In particular, compared to the group cultured in a sodium ion concentration of 130 mM, the groups cultured in a sodium ion concentration of 140 mM, 150 mM, and 160 mM showed significantly lower TRPA1 mRNA expression levels. In the skin, small molecules such as ions are thought to freely diffuse from blood vessels and infiltrate between cells, so it is assumed that the sodium ion concentration in the blood is approximately the same as the sodium ion concentration in the tissue fluid of the skin (Friedel M. et al., Nature Biomedical Engineering, 2023, 7, 1541-1555). Therefore, it is suggested that low serum sodium ion concentrations may increase TRPA1 expression in melanocytes.

[0041] <Reference example 1> Various extracts were prepared using the following procedure. Clove extract (Clove extract): The flower buds of the clove tree were extracted with 90% ethanol, concentrated, and dissolved in 1,3-butylene glycol. Evening Primrose Extract: 1,3-butylene glycol was added to an extract of evening primrose seeds. Soybean extract: An extract obtained by water extraction of soybean seeds, to which 1,3-butylene glycol was added. Meadowsweet extract: The flowers of Meadowsweet were extracted with 1,3-butylene glycol. Rosa multiflora extract: The fruits of Rosa multiflora were extracted with 1,3 - butylene glycol. Hieracium pilosella extract: The flowers of Hieracium pilosella were extracted with 1,3 - butylene glycol. Aesculus turbinata extract: The fruits, leaves, or bark of Aesculus turbinata, extracted with ethanol, were dissolved in 1,3 - butylene glycol.

[0042] <Test Example 2> Examination of the effects of various extracts on the expression level of the TRPA1 gene in melanocytes Following the procedure below, the expression level of the TRPA1 gene in melanocytes to which the test extracts were added was measured.

[0043] Normal human epidermal melanocytes (HEM - d: Human Epidermal Melanocytes - dark, neonatal, male sex, Darkly pigmented, Kurabo Industries Ltd.) were seeded at 6×10 4 cells / well in a 24 - well plate and cultured overnight in an environment of 37°C and 5% CO2. As the medium, Medium254 (Thermo Fisher Scientific Inc., Gibco TM , M254500) was used, to which HMGS Special Proliferation Additive Set (7.5 ml per 500 ml of Medium254) (manufactured by Kurabo Industries Ltd., KM - 6350) and Antibiotic - Antimycotic (100×) (Thermo Fisher Scientific Inc., Gibco TM , 15240 - 062) were added.

[0044] After culturing, the medium was removed and replaced with a medium containing 0.1 wt% of the test extract at a solid content concentration in the "medium with a sodium ion concentration of 130 mM" of Test Example 1, and further cultured for 24 hours in an environment of 37°C and 5% CO2. As the test extracts, those prepared by the methods of the reference examples were all used. Also, as the control medium, the "medium with a sodium ion concentration of 130 mM" of Test Example 1 was used.

[0045] After culturing, the cells were harvested and RNA was extracted using a standard method. cDNA was synthesized from the extracted RNA using a standard method, and PowerTrack TM SYBR Green Master Mix for qPCR (Thermo Fisher Science) TIFIC Corporation, Applied Biosystems TM Using A46111), the RT-qPCR method was used to determine the TR The expression levels of each PA1 gene were analyzed. The GAPDH gene was used as an endogenous control.

[0046] Figures 2-9 show the mRNA expression levels of the TRPA1 gene in melanocytes treated with each extract, expressed as relative values ​​with the TRPA1 gene mRNA expression level in control melanocytes set to 1. In melanocytes treated with any of the extracts, a significant decrease in TRPA1 gene mRNA expression was observed compared to the control group. [Industrial applicability]

[0047] This invention provides an ingredient that suppresses TRPA1 expression. Furthermore, by incorporating such an ingredient into a composition, a whitening composition can be created. These inventions contribute to development in the beauty industry and meet consumer demand, making them highly useful industrially.

Claims

1. A TRPA1 (transient receptor potential ankyrin 1) expression inhibitor containing the following component (a) as the active ingredient: (a) One or more selected from the group consisting of clove extract (Syzygium aromaticum) and evening primrose extract (Oenothera biennis).

2. Furthermore, the TRPA1 expression inhibitor according to claim 1 further contains the following component (b): (b) One or more selected from the group consisting of soybean (Glycine max) extract, meadowsweet (Filipendula ulmaria) extract, wild rose (Rosa canina) extract, cornflower (Centaurea cyanus) extract, and horse chestnut (Aesculus hippocastanum) extract.

3. A TRPA1 expression inhibitor according to claim 1 or 2, which suppresses TRPA1 expression in subjects whose serum sodium ion concentration is 150 mM or less.

4. The TRPA1 expression inhibitor according to claim 3, wherein the subject is one or more subjects selected from the group consisting of pregnant, obese, and elderly.

5. A TRPA1 expression inhibitor according to claim 1 or 2, for use in the summer.

6. A TRPA1 expression inhibitor according to claim 1 or 2, which suppresses the expression of TRPA1 in melanocytes.

7. A composition for inhibiting TRPA1 expression, comprising the TRPA1 expression inhibitor described in claim 1 or 2.

8. A skin-whitening composition containing the TRPA1 expression inhibitor described in claim 1 or 2.

9. The composition according to claim 7, which is a composition for external use on the skin.

10. The composition according to claim 7, which is a cosmetic.

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