A skin-roughening agent for oily skin with reduced moisture content in the stratum corneum

Abstract

To provide a component that can prevent the oily skin with a reduced moisture content of the horny layer from getting rough.SOLUTION: The present invention discloses an agent for suppressing the progress of epidermal cornification due to oleic acid, containing Clematis chinensis Osbeck extract and / or Citrus hystrix DC. leaf extract as an active ingredient, and an agent for preventing a site on skin surface with excessive sebum and a reduced horny-layer moisture content from getting rough.EFFECT: Such agents act on the peculiar phenomena of oily skin with a reduced horny-layer moisture content without resort to external supply of moisturizing component, thus protecting the oily skin against roughening. Those ingredients do not affect the cornification of the skin in normal state, and can have effect only on the roughened site of the oily skin even when non-oily and other types of skin are mixed in different sites of the face.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an agent for improving rough skin for skin conditions in which the amount of sebum on the skin surface is extremely high and the moisture content of the stratum corneum is reduced. [Background technology]

[0002] Skin problems vary depending on skin type, but oily skin, which has a high amount of sebum secreted from the skin surface, is prone to problems such as appearance problems such as shine and glare, as well as acne and enlarged pores. Conventionally, the use of cosmetics containing ingredients that suppress sebum secretion and the removal of sebum using oil-absorbent paper have been proposed as measures against oily skin (Patent Document 1).

[0003] Among oily skin, there are skin with a high stratum corneum moisture content and skin with a low stratum corneum moisture content and dry skin (Non-Patent Document 1). In the latter case, in addition to skin problems common to oily skin such as greasiness and acne, symptoms similar to sensitive skin such as itching and rough skin due to a decrease in the epidermal barrier function appear. In addition, there are cases where the entire face is oily skin with a decreased stratum corneum moisture content, and cases where only part of the face has this skin type.

[0004] On the other hand, it has been reported that oleic acid, a sebum component, has an effect of increasing keratinization of epidermal cells, reduces the epidermal barrier function, and that linoleic acid inhibits the uptake of oleic acid into epidermal cells (Non-Patent Documents 2 and 3). However, it is not known at all that in actual skin, a decrease in the linoleic acid content in sebum intensifies the effect of oleic acid on the epidermis, causing rough skin.

[0005] For oily skin with a high moisture content in the stratum corneum, general methods for treating oily skin such as suppressing sebum secretion and removing sebum are effective, but for oily skin with a low moisture content in the stratum corneum, the above methods can lead to further dryness and sebum secretion due to dryness, which has the opposite effect. Therefore, for oily skin with low moisture content in the stratum corneum, attempts have been made to prevent dryness and improve excessive sebum secretion by using cosmetics with high moisturizing effects. However, these methods can sometimes lead to shininess due to over-moisturization, or cause acne due to excess oil, making it difficult to control the amount of oil and moisture applied to the skin.

[0006] It is known that Sakishima button vine has an effect of inhibiting the lipase activity of Sakishima button vine, which is in the same genus as Sakishima button vine (Patent Document 2), and has protease activity (Patent Document 3).In addition, Kaffir lime is known to have an effect of promoting stratum corneum peeling and desmosome degradation in plants belonging to the genus Citrus (Patent Document 4) and an effect of promoting filaggrin protein production (Patent Document 5).

[0007] However, although the total amount of free fatty acids can be reduced by the effect of inhibiting lipase activity, the effect of reducing the content of specific fatty acids such as oleic acid cannot be expected. In addition, the effect of promoting stratum corneum peeling by protease activity or desmosome degradation cannot suppress hyperkeratinization caused by oleic acid. In addition, although it is possible to temporarily increase the moisture content of the stratum corneum by promoting the production of filaggrin protein, no sustained effect can be expected unless hyperkeratinization caused by oleic acid is suppressed. Therefore, it was completely inconceivable that any of the extracts would be effective against rough skin in oily skin with reduced moisture content in the stratum corneum. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2010-505800 [Patent Document 2] JP 2003-119151 A [Patent Document 3] JP 2003-226613 A [Patent Document 4] JP 2004-010480 A [Patent Document 5] JP 2001-261568 A [Non-patent literature]

[0009] [Non-Patent Document 1] Journal of the Japanese Society of Cosmetic Technologists, Vol. 19, No. 1, 9-19, 1985 [Non-Patent Document 2] Archives of Dermatological Research,291,405-412,1999 [Non-Patent Document 3] Journal of Investigative Dermatology,124(5),1008-1013,2005 Summary of the Invention

[0010] As described below, the inventors of the present application have found that in oily skin with low stratum corneum moisture content, the linoleic acid content in sebum is reduced for some reason, and the keratinization-promoting effect of oleic acid is enhanced, resulting in rough skin. Based on this finding, the inventors have come to believe that in skin with a reduced linoleic acid content in sebum, such as oily skin with reduced stratum corneum moisture content, the improvement of rough skin can be expected by suppressing the keratinization-promoting effect of oleic acid. The present invention is based on the above finding. [Problem to be solved by the invention]

[0011] To develop an ingredient that can improve rough skin in oily skin with reduced moisture content in the stratum corneum, and that improves the condition by acting on causes specific to the skin type, rather than by supplying a moisturizing ingredient from the outside. [Means for solving the problem]

[0012] The above problem was solved by using Sakishima buttonwood extract and / or Kaffir lime leaf extract to inhibit increased keratinization caused by oleic acid, which is the cause of rough skin in oily skin with reduced stratum corneum moisture content. Effect of the Invention

[0013] According to the present invention, it is possible to improve rough skin in oily skin without relying on the supply of moisturizing ingredients from the outside by acting on a phenomenon specific to oily skin in which the moisture content of the stratum corneum is reduced. Furthermore, none of the extracts has any effect on the keratinization of normal skin, and even if different skin types are mixed on different parts of the face, they can be effective only on the rough parts of the skin of the skin type. [Brief description of the drawings]

[0014] [Figure 1] Tree diagram obtained by cluster analysis using skin measurement results [Diagram 2] Comparison of sebum amount, stratum corneum water content, and transepidermal water loss between normal skin and two types of oily skin [Diagram 3] A comparison of the amount of linoleic acid and oleic acid in sebum by skin type [Figure 4] Figure showing the effect of samples with different fatty acid composition on stratum corneum moisture content and transepidermal water loss [Diagram 5] Figure showing the effect of samples with different fatty acid composition on stratum corneum cell area [Figure 6] A graph showing the degree to which the addition of various plant extracts inhibits the hyperkeratosis of oleic acid-added epidermal cells. [Figure 7] Figure showing the effect of adding various plant extracts on the keratinization of epidermal cells to which oleic acid has not been added DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The Clematis chinensis extract used in the present invention includes an extract obtained from Clematis chinensis Osbeck as an extraction raw material, a dilution or concentrate of the extract, a dried product obtained by drying the extract, or a crude or purified product thereof. There are no particular limitations on the part used as the extraction raw material, and any part may be the leaves, stems, roots, seeds, etc., or the whole plant, and any part may be used either raw or dried. Of these, it is particularly preferable to use the root as the extraction raw material.

[0016] The kaffir lime leaf extract used in the present invention includes an extract obtained from kaffir lime (Citrus hystrix DC.) as an extraction raw material, a dilution or concentrate of the extract, a dried product obtained by drying the extract, or a crude or purified product thereof. The part used as the extraction raw material is the leaves, and the leaves can be used either raw or dried.

[0017] The extraction solvent for the extract of Coix seed oil and the extract of Kaffir lime leaves used in the present invention is not particularly limited, and may be, for example, water, lower alcohols such as methanol, ethanol, and propyl alcohol, or polyhydric alcohols such as propylene glycol and 1,3-butylene glycol, among which it is particularly preferred to select one or more of water, ethanol, and 1,3-butylene glycol.

[0018] The method of extracting the Sakishima button vine extract and the Kaffir lime leaf extract used in the present invention is not particularly limited. For example, 1 to 100 parts by mass of an extraction solvent may be used per 1 part by mass of dried plant, and the extract may be extracted by heating, or at low or normal temperature. After extraction, the extract may be filtered and used as it is, but if necessary, it may be purified by deodorization, decolorization, etc., to the extent that the effect is not affected. Furthermore, the extract may be freeze-dried or used in powder form.

[0019] The amount of each of the extract of Sakishima button crest and the extract of Kaffir lime leaf in the total composition is not particularly limited as long as it is effective, but whether they are used alone or in combination, the amount is preferably 0.001 to 10 mass%, and more preferably 0.001 to 0.1 mass%, calculated on a dry mass basis.

[0020] In addition to the above essential components, the rough skin improving agent of the present invention can be appropriately blended with aqueous components, oily components, plant extracts, animal extracts, powders, surfactants, oils, alcohols, pH adjusters, preservatives, antioxidants, thickeners, colorants, fragrances, etc. used in cosmetics, quasi-drugs, and pharmaceuticals, as necessary, within the range that achieves the object of the present invention. The external skin agent of the present invention can be in various dosage forms, such as lotion, milky lotion, cream, pack, powder, spray / ointment, dispersion, and cleanser. EXAMPLES

[0021] Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

[0022] [Experiment 1: Classification of panelists' skin types using cluster analysis] First, skin measurements were taken to classify the skin types of the panelists. Fifteen women in their 20s to 40s were asked to wash their faces with face wash, then acclimatize for 10 minutes in an environment of 22±1°C and 50±2% humidity, after which the amount of sebum, stratum corneum moisture, and transepidermal water loss on the cheeks were measured. Sebumater SM815 (Courage+Khazaka) was used to measure the amount of sebum, Corneometer CM825 (Courage+Khazaka) to measure the amount of stratum corneum moisture, and Vapometer (Delfin) to measure the amount of transepidermal water loss. The same machines were used in other experiments unless otherwise noted.

[0023] A cluster analysis was performed using the Ward method with the above three measurement results as parameters, and the tree diagram shown in Figure 1 was obtained. The panelists' skin types were divided into four groups along the dotted lines in the figure, and classified from top to bottom into oily skin with high stratum corneum moisture content (represented as moisture + in the figure), normal skin, dry skin, and oily skin with reduced stratum corneum moisture content (represented as moisture - in the figure) based on trends in sebum amount, stratum corneum moisture content, and transepidermal water loss (represented as TEWL in the figure).

[0024] Figure 2 shows the results of a comparison of sebum amount, stratum corneum moisture content, and transepidermal water loss between normal skin and two types of oily skin classified by cluster analysis. Both types of oily skin had more sebum than normal skin. Furthermore, oily skin with reduced stratum corneum moisture content had lower stratum corneum moisture content and higher transepidermal water loss than oily skin with high stratum corneum moisture content, and as these reflected the characteristics of skin type, the results of the cluster analysis were deemed valid. The skin type classification obtained here was used in subsequent experiments.

[0025] [Experiment 2: Confirmation of sebum composition characteristic of oily skin with low stratum corneum moisture content] Next, the amount of fatty acids in sebum was analyzed by the following procedure. Sebum was collected by pressing a sebum-removing film (9 cm x 5.5 cm) against the inside of the cheek of the subject. The tape with sebum attached was mixed with a tube containing diethyl ether, and the sebum was dissolved. The diethyl ether was then dried at 40°C to obtain sebum. 100 μl of chloroform was added per 1 mg of collected sebum, and the solvent was dried at 70°C to obtain a sebum sample, which was used for fatty acid analysis. The sebum sample and fatty acid specimen were methylated using a fatty acid methylation kit (manufactured by Nacalai Tesque), and the amount of each fatty acid contained in the sebum was detected by gas chromatography analysis (column: 3.2 mmφ x 1.1 m packed column, packing material: DEGS, 15% Chromosorb W, column temperature: 175°C).

[0026] Figure 3 shows the content of linoleic acid and oleic acid in sebum for normal skin, oily skin with high stratum corneum moisture content, and oily skin with low stratum corneum moisture content. This study revealed that there is almost no difference in the oleic acid content between skin types, but that in oily skin with reduced stratum corneum moisture content, the linoleic acid content relative to the total sebum volume is significantly reduced. These results suggest that rough skin in oily skin with low moisture content in the stratum corneum is caused by a decrease in the linoleic acid content in sebum, which results in a pronounced keratinization-promoting effect of oleic acid.

[0027] [Experiment 3: Verification of the effect of changes in linoleic acid content in sebum on skin condition] In fact, a fatty acid application test was conducted to verify whether a decrease in the linoleic acid content in sebum would result in similar characteristics to oily skin with low stratum corneum moisture, and whether the keratinization-promoting effect of oleic acid would be enhanced. The composition of each sample is shown in Table 1. 95 v / v % ethanol was used as the solvent, and 10 v / v % oleic acid and 0.3, 0.06, and 0 v / v % linoleic acid were mixed therein.

[0028] [Table 1]

[0029] Seven male subjects in their 30s and 40s were tested on the inside of their forearms, and each sample was applied for two weeks. On the test start day and two weeks after the start of the test, transepidermal water loss and stratum corneum moisture content were measured, and stratum corneum samples were taken to measure stratum corneum cell area.

[0030] [Method of measuring stratum corneum cell area] Corneal layer cells were collected from the test site using a stratum corneum checker (plastic plate type, manufactured by Promo Tools). The stratum corneum checker was immersed in ethanol for 2 minutes, dried, and stained with hematoxylin-eosin. Images of the stratum corneum after the above treatment were obtained using a fluorescent microscope (BZ-X700, KEYENCE, 400x magnification), and the outlines of the cells on the printed image were traced and scanned using a scanner (Docucenter-V C4476, Fuji Xerox). The outlines of the cells were extracted using image analysis software, and the area within the outlines was measured.

[0031] Figure 4 compares the changes in stratum corneum moisture content and transepidermal water loss over a two-week period at the sites where each sample was applied. Between the groups that applied samples 1 to 3, a decrease in stratum corneum moisture content and an increase in transepidermal water loss were observed as the linoleic acid content in the sample decreased, which was consistent with the characteristics of oily skin with low stratum corneum moisture content. Therefore, it was found that the dryness in the stratum corneum in this skin type is caused by a decrease in the linoleic acid content in sebum. In addition, as shown in Figure 5, when comparing the change in stratum corneum cell area over two weeks between the groups that applied samples 1 to 3, the stratum corneum cell area was significantly reduced as the linoleic acid content in the sample decreased. It is known that epidermal cells cannot be sufficiently flattened when keratinization is accelerated, and a reduction in the stratum corneum cell area is considered to indicate accelerated keratinization. Therefore, it was found that the keratinization-enhancing effect of oleic acid is enhanced when the linoleic acid content in sebum decreases.

[0032] Until now, the cause of rough skin in oily skin with low moisture content in the stratum corneum was unclear. However, based on the above findings, it can be said that in this skin type, the reduced linoleic acid content in sebum means that the effect of oleic acid on the skin cannot be fully suppressed, resulting in a pronounced hyperkeratinization effect and rough skin. Therefore, for skin with this skin type, where the adverse effects of oleic acid have become stronger due to a decrease in the linoleic acid content in sebum, it was expected that suppressing these adverse effects would lead to improvement of rough skin, so active ingredients that suppress the increased keratinization caused by oleic acid were screened.

[0033] Example 1: Screening using the degree of hyperkeratosis of epidermal cells supplemented with oleic acid as an index Screening of skin roughness improving agents for oily skin with reduced stratum corneum moisture was carried out using the degree of hyperkeratinization of epidermal cells to which oleic acid had been added as an index, as follows: The degree of hyperkeratinization was measured using the change in the expression level of the gene encoding transglutaminase 1 (TGM1), a protein whose expression level increases with the keratinization of epidermal cells. Preparation of test substances 500mL of purified water was added to 20g of dried Clematis chinensis Osbeck roots, and the mixture was extracted at 80℃ for 8 hours. The extract was dissolved in 50v / v% 1,3-butylene glycol solution to make the concentration 1.5w / v%, to obtain Clematis chinensis extract. 200mL of 80v / v% ethanol was added to 20g of dried Citrus hystrix DC. leaves, and the extract was extracted at 80℃ for 2 hours. The extract was dissolved in 70v / v% 1,3-butylene glycol solution to make the concentration 1.0w / v%, to obtain Kaffir lime leaf extract. 100 mL of 50 v / v% ethanol was added to 20 g each of dried plum (Prunus mume) fruit and lemon (Citrus Limon Burmann fil.) fruit, and the extract was left to stand at room temperature (approximately 25°C) for one week. The components obtained were then dissolved in 50 v / v% 1,3-butylene glycol solution to make the concentrations 1.5 w / v% and 1.0 w / v%, respectively, to obtain plum extract and lemon extract.

[0034] [Cell culture] Normal human epidermal keratinocytes (Passage2, Invitrogen) were added at 4.0 × 10 4The cells were dispersed in medium (Epilife, Invitrogen) at a concentration of 1000 cells / mL, and 500 μL of each solution was seeded in a 24-well plate (True Line). After culturing for one day at 37°C under 5% CO2, the medium was removed, and Epilife medium with a calcium ion concentration of 0.03 mM and 0.25 v / v% of the test substance were added. After further incubation for one day, oleic acid (Fujifilm Wako Pure Chemical Industries) dissolved in ethanol was added to each well to a concentration of 20 μM. After culturing for one day, RNA was extracted using an RNA extraction kit (Total RNA Purification Kit, Jena Bioscience).

[0035] [cDNA synthesis and real-time PCR] Then, reverse transcription was performed using PrimeScript RT Reagent Kit (TaKaRa) to synthesize cDNA. Using the obtained cDNA as a template, the expression levels of transglutaminase 1 (TGM1) and GAPDH (glyceraldehyde 3-phosphate dehydrogenase; used as a housekeeping gene) were measured by real-time PCR (7500 Real Time PCR System, Applied Biosystems) using the following primers and enzymes. The primers used were a sense primer for TGM1 (5'-TCCGAGAGGGCATGCTAGTAG-3'), an antisense primer (5'-GCACTATCAGCTCGTCGTACTCA-3'), a sense primer for GAPDH (5'-CCACATCGC TCAGACACCAT-3'), and an antisense primer (5'-TGACCAGGC GCCCAATA-3'). Power SYBR Green Master Mix (Applied Biosystems) was used for the PCR reaction, and gene expression was analyzed by the comparative Ct method. In other words, the change in gene expression level due to the addition of the test substance was calculated as the relative amount to the TGM1 Ct value in the control group to which no oleic acid was added, which was corrected by the GAPDH Ct value, which was set to 1.

[0036] As shown in Figure 6, the expression level of the keratinization-related gene TGM1 in epidermal cells, which increased with the addition of oleic acid, was reduced in the groups to which Sakishima button crest extract and Kaffir lime leaf extract were added, indicating that Sakishima button crest extract and Kaffir lime leaf extract can suppress the increased keratinization effect of oleic acid in epidermal cells. On the other hand, although it has been reported that lemon extract and plum extract have moisturizing effects and improve skin barrier function, the expression level of TGM1, which increased with the addition of oleic acid, did not decrease but rather increased. Therefore, it was thought that the moisturizing effect and the effect of improving skin barrier function were not linked to the inhibitory effect of oleic acid on increased keratinization.

[0037] Example 2: Examination of the effect of oleic acid not added on the degree of cell differentiation of epidermal cells The following procedure was used to confirm the effects of the Sakishima buttonwood extract and Kaffir lime leaf extract, which suppressed the keratinization-enhancing effect of oleic acid in epidermal cells in Example 1, on the expression level of the keratinization-related gene TGM1. Preparation of test substances An extract of Sakishima buttonwood and an extract of Kaffir lime leaves prepared in the same manner as in Example 1 were used. [Investigation of the effect of test substances on the expression level of the keratinization-related gene TGM1] Normal human epidermal keratinocytes (Passage2, Invitrogen) were added at 4.0 × 10 4 The cells were dispersed in a medium (Epilife, Invitrogen) at a concentration of 1000 cells / mL, and 500 μL of each solution was seeded in a 24-well plate (True Line). After culturing at 37°C and 5% CO2 for one day, the medium was removed, and Epilife medium with a calcium concentration of 0.03 mM and 0.25 v / v% of the test substance were added. After culturing for another two days, total RNA was extracted, and the gene expression level of TGM1 was measured in the same manner as in <Example 1>.

[0038] As shown in Figure 7, it was confirmed that the Sakishima button crest extract and Kaffir lime leaf extract had almost no change in the expression level of the keratinization-related gene TGM1 in epidermal cells to which oleic acid was not added. In other words, the Sakishima button crest extract and Kaffir lime leaf extract themselves do not have the effect of suppressing keratinization of epidermal cells, and the effect confirmed in Figure 6 was confirmed to be a specific effect on the promotion of keratinization by oleic acid.

[0039] In [Experiment 3], it was found that when oleic acid was applied to the skin, its keratinization-promoting effect caused a decrease in the moisture content of the stratum corneum, an increase in transepidermal water loss, and a decrease in the area of ​​stratum corneum cells, resulting in characteristics similar to those of oily skin, which has a decreased moisture content in the stratum corneum. Sakishima button crane extract and Kaffir lime leaf extract have the effect of suppressing increased keratinization caused by oleic acid, so when applied to the skin, they are expected to suppress increased keratinization in oily skin with reduced moisture content in the stratum corneum, and prevent rough skin in such skin types.

[0040] According to the present invention, by using Sakishima buttonwood extract and Kaffir lime leaf extract, it is possible to suppress hyperkeratinization caused by oleic acid and improve rough skin in areas where the skin surface has excess sebum and reduced moisture content in the stratum corneum. In addition, the extract itself does not have any effect in inhibiting the keratinization of epidermal cells, so it has no effect on areas that are in a normal state. Therefore, even if the skin quality differs depending on the part of the face, skin care using cosmetics containing Sakishima button vine extract and Kaffir lime leaf extract on the entire face will act specifically on the parts of the skin where the surface of the skin is oversebum and the stratum corneum moisture content is low, improving rough skin.

Claims

1. 1. An agent for suppressing increased epidermal keratinization caused by oleic acid, comprising an extract of Clematis chinensis Osbeck and / or an extract of kaffir lime leaves (Citrus hystrix DC.) as an active ingredient.

2. An agent for improving rough skin in areas where the skin surface has excess sebum and the stratum corneum moisture content is reduced due to oleic acid, comprising an extract of Clematis chinensis Osbeck and / or an extract of kaffir lime leaves.

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