JP2012001481A - Skin care preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a skin care preparation, which uses poly-γ-L-glutamic acid and has a moisture-retaining effect excellent in temporal stability, especially excellent in usability.SOLUTION: The skin care preparation includes 0.0001 to 10 wt.% of poly-γ-L-glutamic acid and/or a salt thereof and 0.1 to 60 wt.% of a silicone oil, and has a blending weight ratio of a poly-γ-L-glutamic acid and/or a salt thereof/silicone oil of 1/1 to 1/40,000.

Description

The present invention relates to an external preparation for skin, and more particularly to an external preparation for skin with improved usability.

Human skin is covered by the stratum corneum, and life activity can be maintained without losing moisture even in a dry atmosphere because the stratum corneum is in contact with the outside world. well known. The stratum corneum is thin and flexible and maintains moisture in the body and is adjusted to maintain a healthy skin state.

However, we often cause some damage to the epidermis due to environmental factors (eg temperature change, humidity change, light, contact with water, use of detergents, etc.). Damaged skin is hard, loses elasticity, and becomes rough and rough. Such rough skin has recently been pointed out to be associated with atopic dermatitis, which is rapidly increasing, and may cause serious skin troubles.

Rough skin may be due to exfoliation of keratinocytes, or may be caused by dryness and deterioration of skin health leading to hardening or damage of the epidermis. The former rough skin is elution of keratinocyte lipids such as cholesterol, ceramide, fatty acid, and the formation of stratum corneum permeation barrier due to degeneration of keratinocytes caused by UV rays, detergents, etc. Caused by. For the purpose of preventing or healing this rough skin, studies have been made on supplying a keratinocyte lipid component or a synthetic keratinocyte lipid similar thereto. This stratum corneum intercellular lipid is a lamellar granule that is biosynthesized by cells in the spinous layer and the granule layer, and is released between the cells just below the stratum corneum and extends, taking a lamellar (lamellar) structure. It has spread to. The lamellar granule is composed of glucosylceramide, cholesterol, ceramide, phospholipid, etc., but the horny layer intercellular lipid hardly contains glucosylceramide. That is, glucosylceramide in lamellar granules is hydrolyzed by β-glucocerebrosidase and converted to ceramide. As a result of this ceramide having a lamellar structure, formation of a stratum corneum permeation barrier is improved as a stratum corneum intercellular lipid. Therefore, it is considered to have a barrier function for preventing rough skin. It has been reported that ceramide supplementation is effective for rough skin caused by a cleaning agent, and shows a high effect in improving rough skin (Non-patent Document 1).

On the other hand, for the latter rough skin, the topical skin preparation maintains the skin's homeostasis and prevents water from evaporating from the skin, keeping the skin and stratum corneum constituting the skin to retain moisture, and keeping the skin moisturized and flexible. A moisturizing agent is blended for the purpose of keeping the skin clean and fresh. Conventionally used moisturizers include glycerin, 1, 3 as hydrophilic moisturizers in addition to lipophilic moisturizers typified by vegetable oils such as olive oil and animal-derived lipids such as lanolin. -Water-soluble polyhydric alcohols such as butylene glycol, propylene glycol, sorbitol, polysaccharides such as hyaluronic acid and xanthan gum, water-soluble polymers such as polyethylene glycol, low molecular weight natural moisturizing typified by pyrrolidone carboxylates and amino acids Factors, plant extracts and the like are known.

There are various types of hydrophilic and lipophilic moisturizers as described above. However, due to the trend of emphasizing safety, animal-derived products and chemical synthetic products tend to be avoided recently, preferably natural. Biodegradable materials that are fermented products by products and microorganisms and that have less burden on the environment as well as the living body are expected and attracting attention.

On the other hand, biopolymers produced by microorganisms are promising. Among biopolymers, various functions have been found in a group of biopolymers called polyamino acids constituted by condensation polymerization of amino acids, and attention has been focused on their potential. Conventionally, three types of polyamino acids have been identified: poly-γ-glutamic acid (hereinafter sometimes referred to as “PGA”), poly-ε-lysine and cyanophysin.

PGA is a polyamino acid in which an α-amino group and a γ-carboxyl group of glutamic acid are amide-bonded. PGA is a water-absorbing polyamino acid known as the main material of stringing of natto, which has been familiar to Japanese people for a long time, but as a background of this familiarity, it is due to its attractive functionality. large. As an attractive function of PGA, it is known that it has both biodegradability and high water absorption. Utilizing these functions, it is expected to be used in various fields and applications including the above-mentioned external preparations for skin, medical products, foods and the like.

Recently, it has been found that structural characteristics of polyamino acids (optical activity and type of constituent amino acids, molecular size, binding mode, etc.) are strongly reflected in their functionality. A well-known point is that it has both biodegradability and high water absorption. Utilizing these functions, it is expected to have various applications in many fields such as foods, cosmetics, and medical products. However, currently commercially available PGA is a chemically heterogeneous DL-PGA. Specifically, PGA is produced from Bacillus natto and its related bacteria, and D-glutamic acid and L-glutamic acid are irregularly bound, and the content ratio and sequence vary depending on the culture of the producing bacteria. In general, the structural characteristics of polyamino acids (optical activity and type of constituent amino acids, molecular size, binding mode, etc.) strongly influence their functions. Since the DL-PGA has a different structure for each molecule, its property also differs for each molecule. This makes it difficult to stably produce DL-PGA having a desired quality.

Bacteria that produce homopoly-γ-glutamic acid have also been reported. For example, Bacillus anthracis has been reported to produce poly-γ-D-glutamic acid (hereinafter sometimes referred to as D-PGA) consisting only of D-glutamic acid (Non-patent Document 2). However, since this bacterium is a bacterium having a strong pathogenicity, it is inappropriate as an industrial PGA-producing bacterium, and the molecular weight of D-PGA produced is small. In addition, it has been reported that the alkalophilic bacterium Bacillus halodurans produces poly-γ-L-glutamic acid and / or a salt thereof (hereinafter sometimes referred to as L-PGA) consisting only of L-glutamic acid (non-native). Patent Document 3). However, L-PGA produced by this bacterium has an extremely small molecular weight, and is insufficient to obtain practical performance.

On the other hand, it has been reported that the halophilic archaeon Natrialba aegyptiaca produces L-PGA having a molecular weight of about 100,000 to 1,000,000 as a high-molecular-weight homopoly-γ-glutamic acid-producing bacterium. However, since this bacterium has a molecular weight as small as about 100,000 under liquid culture conditions and hardly produces poly-γ-L-glutamic acid and / or a salt thereof, there is a problem as an industrially producing bacterium (non-patent) Document 4, Patent Document 1).

In addition to the above, examples of organisms that produce L-PGA include hydra and the like, but hydra also has a problem that its molecular weight is extremely small (Non-patent Document 3).

On the other hand, the present inventors made it possible to prepare a large amount of poly-γ-L-glutamic acid and / or a salt thereof with uniform optical purity and high molecular weight by liquid culture or the like. More specifically, poly-γ-L-glutamic acid and / or a salt thereof having a number average molecular weight of 1.3 million or more and uniform optical purity are obtained with a high productivity of 4.99 g or more per liter of culture solution. (Patent Document 2).

Moreover, the crosslinking method of poly-γ-L-glutamic acid and a crosslinked product (Patent Document 3), and at least one of poly-γ-L-glutamic acid and poly-γ-L-glutamic acid crosslinked product are included. There is a report of an external preparation for skin (Patent Document 4).

In general, a state where the skin stratum corneum contains 10 to 15% of water is said to be healthy skin. If it contains too much moisture, it will become dandruff, and if it is too little, it will become crisp. In order to solve this, hyaluronic acid having an excellent moisturizing ability regardless of the outside air humidity is used as a moisturizing agent in external preparations for skin, such as lotions, creams and emulsions. In addition to hyaluronic acid, for example, sodium lactate, glycerin, 1,3-butylene glycol, propylene glycol and the like are used in these skin external preparations in a relatively large amount from the viewpoint of skin affinity and feeling of use. It has been.

However, even in a skin external preparation formulated with hyaluronic acid having a relatively excellent moisturizing ability, when used for a long time under low humidity, the moisture in the external preparation is volatilized into the outside air, not only the moisturizing effect is lost, In some cases, moisture is taken in from the skin to the external preparation for the skin, and the skin may be dried, which is not sufficient in terms of the stability over time of the moisturizing effect. Among the humectants, hyaluronic acid, in particular, has a problem that it causes a strong sticky feeling to the skin even in a small amount. In addition, the moisturizer other than hyaluronic acid is often added in an extremely large amount especially in a skin external preparation that appeals for a rich feeling, so that the stickiness is further increased.

Special Table 2002-517204 JP 2007-314434 A JP 2008-120910 A JP 2008-120725 A

Journal of Bioscience and Bioengineering, 94,187 (2002) Handy, W. E., and H.N.Rydon, Biochem J., 40, 297-309 (1946) Biology and Chemistry Vol.40, No.4, p212-214 (2002) Hezayen, F. F., B. H. A. Rehm, B. J. Tindall and A. Steinbuchel, Int. J. Syst. E., 51, 1133-1142 (2001)

An object of the present invention is to provide a skin external preparation using poly-γ-L-glutamic acid, having a moisturizing effect excellent in stability over time, and particularly excellent in usability. Is.

In such a situation, the present inventors conducted intensive research and found that a skin external preparation formulated with silicone oil is superior in stability over time of the moisturizing effect, in particular, usability, and completed the present invention. .

That is, the present invention has the following configuration.
(1) Poly-γ-L-glutamic acid and / or a salt thereof 0.0001 to 10% by weight and silicone oil 0.1 to 60% by weight, and poly-γ-L-glutamic acid and / or its An external preparation for skin, wherein the blending weight ratio of salt and silicone oil is from 1/1 to 1/40000.
(2) Poly-γ-L-glutamic acid is a cross-linked poly-γ-L-glutamic acid characterized by having a cross-linked structure between poly-γ-L-glutamic acid molecules (1) Topical skin preparation.
(3) The skin external preparation of (1) or (2), wherein the average molecular weight of poly-γ-L-glutamic acid is 1,000,000 or more.
(4) The skin external preparation according to any one of (1) to (3), wherein the average molecular weight of poly-γ-L-glutamic acid is 2 million or more.
(5) The skin external preparation according to any one of (1) to (4), wherein the average molecular weight of poly-γ-L-glutamic acid is 3.5 million or more.
(6) The external skin preparation according to any one of (1) to (5), wherein the water absorption ratio of poly-γ-L-glutamic acid is 10 to 5000 times.

ADVANTAGE OF THE INVENTION By this invention, the skin external preparation excellent in the percutaneous absorption promotion effect of hydroquinone glycoside and excellent in safety can be provided.

The “poly-γ-L-glutamic acid” of the present invention is a homopolymer consisting only of L-glutamic acid. Its structure is the structure represented by formula (I). The hydrogen of α-COOH may be hydrogen or another metal counter ion. For example, there is no need to limit the general materials such as sodium, potassium, magnesium, manganese, calcium, zinc and iron. Of these, sodium is preferred.

The “molecular weight” of the present invention refers to the number average molecular weight (Mn) calculated in terms of the molecular weight of the pullulan standard substance.

The poly-γ-L-glutamic acid of the present invention can be obtained by an existing method. For example, poly-γ-L-glutamic acid can be obtained by the method described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-314434). Hereinafter, as an example, a method for producing poly-γ-L-glutamic acid with reference to Patent Document 2 will be described, but the present invention is not limited thereto.

For example, the National Institute of Advanced Industrial Science and Technology (AIST) Patent Biological Depositary Center has a Natrialba aegyptiaca 0830-82 strain (trusted organization: National Institute of Advanced Industrial Science and Technology Patent Biological Depositary Center), date of deposit: Heisei April 4, 2006, accession number: FERM BP-20872), Natrialba aegyptiaca 0830-243 strain (trusted institution: National Institute of Advanced Industrial Science and Technology, Patent Organism Depositary), accession date: 2006 April 4, 2000, accession number: FERM BP-20873), or Natrialba aegyptiaca 0831-264 strain (trusted institution name: National Institute of Advanced Industrial Science and Technology, Patent Biological Depositary Center), trust date: 2006 Deposited on April 4, 2000 as accession number: FERM BP-20874) To obtain poly-gamma-L-glutamic acid using a with that strain, it is possible to obtain poly-gamma-L-glutamic acid by liquid culture. Alternatively, a microorganism can be mutated by the method described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-314434) to produce a microorganism capable of producing poly-γ-L-glutamic acid by liquid culture, and poly-γ-L- Glutamic acid can also be produced. Moreover, it is also possible to produce poly-γ-L-glutamic acid by solid-phase culture of Natrialba aegyptiaca by a conventional method.

In the case of liquid culture, it is desirable to perform under aerobic conditions such as shaking culture and aeration and agitation culture. The culture temperature at that time is 30 to 50 ° C, preferably 35 to 45 ° C. The pH of the medium can be adjusted with sodium hydroxide, potassium hydroxide, ammonia, hydrochloric acid, sulfuric acid, or an aqueous solution thereof, but is not limited as long as the pH can be adjusted. It is desirable to culture at a culture pH of 5.0 to 9.0, preferably at a pH of 6.0 to 8.5. In addition, the culture period is usually about 2 to 7 days. Further, it is desirable to culture at a NaCl concentration of 10 to 30%, preferably 15 to 25% during culture. Further, it is desirable to culture at a yeast extract concentration of 0.1 to 10%, preferably 0.5 to 5.0%. Also in the case of solid culture, the culture temperature is 30 to 50 ° C., preferably 35 to 45 ° C., and the pH during the culture is 5.0 to 9.0, preferably pH 6.0, in the case of liquid culture and application. -8.5, NaCl concentration during culture is 10-30%, preferably 15-25%, Yeast Extract concentration is 0.1-10%, preferably 0.5-5%. When cultured in this manner, poly-γ-L-glutamic acid is mainly accumulated outside the cells and contained in the culture described above. Although not specifically limited, PGA production liquid medium-1 (22.5% NaCl, 2% MgSO ₄ .7H ₂ O, 0.2% KCl, 3% Trisodium Citrate, 1% Yeast Extract, 0.75% Casamino acid ) May be used, and the amount of each additive may be appropriately adjusted according to the strain.

As a method for quantifying poly-γ-L-glutamic acid in a culture solution, precipitation is carried out from a sample containing poly-γ-L-glutamic acid using copper sulfate or ethanol, and the weight measurement of the precipitate and the Kijderder method (M. Bovarnick, J. Biol. Chem., 145, 415, 1942), a method for measuring the amount of glutamic acid after hydrochloric acid hydrolysis (RD Housewright, CB Thorne, J. Bacteriol., 60, 89, 1950) and a colorimetric method using quantitative binding with basic dyes (M. Bovarnick et al., J. Biol). Chem., 207, 593, 1954), preferably using quantitative binding with basic dyes. A color process.

Examples of basic dyes include crystal violet, aniline blue, safranino, methylene blue, methyl violet, toluine nebula, congo red, azocarmine, thionine, and hematoxylin, with safranino being preferred.

In order to separate and collect poly-γ-L-glutamic acid from this culture, the above-mentioned known methods such as precipitation using copper sulfate or ethanol may be used. As an example, for example, the culture solution is centrifuged to remove the cells. Subsequently, after adding and diluting 3 times the amount of water to the obtained supernatant, the pH is adjusted to 3.0. After pH adjustment, the mixture was stirred at room temperature for 5 hours. Thereafter, 3 times the amount of ethanol was added, and poly-γ-L-glutamic acid was recovered as a precipitate. The precipitate is dissolved in 0.1 mM Tris-HCl buffer (pH 8.0), and low-molecular substances are removed by dialysis. After dialysis, the resulting solution may be treated with DNase or RNase for nucleic acid removal, and then with proteinase treatment for protein removal. After the proteinase treatment, the low molecular weight substance may be removed by dialysis. After dialysis, dry poly-γ-L-glutamic acid may be obtained by freeze-drying or the like. Moreover, although refinement | purification using an anion exchange resin can be performed if necessary, it can refine | purify on general conditions.

The molecular weight of poly-γ-L-glutamic acid used in the present invention is not particularly limited, but is preferably 500,000 or more, more preferably 800,000 or more, still more preferably 1,000,000 or more, and particularly preferably 1.3 million or more.

The upper limit value of the molecular weight of L-PGA is not particularly limited, but according to the above-described L-PGA production method, for example, L-PGA having 6 million or 15 million at the maximum can be obtained.

Since this poly-γ-L-glutamic acid and / or salt thereof is produced by archaea, the specific odor is reduced compared to poly-γ-L-glutamic acid and / or its salt produced by Bacillus natto. Thus, the quality is not impaired even when used for cosmetics, quasi-drugs, medical supplies, hygiene products, or pharmaceutical applications.

The silicone oil used in the present invention may be any organosilicon compound having a siloxane bond, such as methylpolysiloxane, dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, decamethylcyclopentasiloxane, Examples include octamethylcyclotetrasiloxane and polyoxyethylene / methylpolysiloxane copolymer.

The viscosity of the silicone oil used in the present invention is preferably about 6 to 100 cSt. If the viscosity is too low, the stability over time of the moisturizing effect may be reduced or the sticky feeling of acetylated hyaluronic acid may not be suppressed. If the viscosity is too high, the silicone oil itself may be sticky.

The amount of the silicone oil used in the present invention is preferably 0.1 to 60% by weight. If the amount of the silicone oil is too small, it may be difficult to sufficiently suppress the stickiness of the external preparation, and it may not be possible to improve the stability over time of the moisturizing effect. This is not preferable.

The topical skin preparation of the present invention includes cosmetic lotions and nutritional creams such as normal skin conditioning and nutritional lotion, as well as water-based cosmetics such as astringent lotion, shave lotion, body lotion and liquid pack, eye cream, body The main products are creams such as cream, hand cream, massage cream, and cold cream, nutritional milk, body milk, neck milk, milk such as hand milk, and packs.

The external preparation for skin of the present invention generally includes surfactants, oils, moisturizers, ultraviolet absorbers, alcohols, chelating agents, preservatives, thickeners, pigments, and fragrances, which are generally used for cosmetics and quasi drugs. Etc. can be mix | blended.

Hereinafter, the present invention will be described in more detail based on examples. The present invention is not particularly limited to the examples. Moreover, all the academic literatures and patent literatures described in this specification are incorporated herein by reference. In the following examples, “%” is “% by weight”.

[Production Example 1; Production of poly-γ-L-glutamic acid]
To an L dry ampoule of Natrialba aegyptica (Accession Number: FERM BP-10749), 0.4 ml of PGA production liquid medium (22.5% NaCl, 2% MgSO ₄ .7H ₂ O, 0.2% KCl, 3% (Trisodium Citrate, 1% Yeast Extract, 0.75% Casamino acid) was added to obtain a suspension. 0.2 ml of the suspension was added to PGA agar medium (10% NaCl, 2% MgSO ₄ .7H ₂ O, 0.2% KCl, 3% Trisodium Citrate, 1% Yeast Extract, 0.75% Casamino acid, 2% Agar) and cultured at 37 ° C. for 3 days to obtain a single colony.

Next, in each of five 18 ml test tubes, 3 ml of PGA production liquid medium (22.5% NaCl, 2% MgSO ₄ .7H ₂ O, 0.2% KCl, 3% Trisodium Citrate, 1% Yeast Extract, 0.75% Casamino acid, pH 7.2) was added, and the single colony was scraped and inoculated with one platinum ear with a platinum ear. The test tube after inoculation was cultured at 37 ° C. and 300 rpm for 3 days, and 0.5 ml of the obtained culture solution was inoculated into 10 500 ml Sakaguchi flasks each containing 50 ml PGA production liquid medium. And cultured at 37 ° C. for 5 days. After culturing, the obtained culture solution was centrifuged, the cells were removed, and the supernatant was collected.

Next, 3 times the amount of water was added to the collected supernatant for dilution, and then the pH was adjusted to 3.0 with 1N sulfuric acid. After adjusting the pH, the mixture was stirred at room temperature for 5 hours. Thereafter, 3 times the amount of ethanol was added and centrifuged, and the precipitate was collected. This precipitate is L-PGA.

The collected L-PGA was dissolved in 0.1 mM Tris-HCl buffer (pH 8.0), and dialyzed to remove impurities such as low molecular weight substances. Next, in order to remove nucleic acid contained in the liquid after dialysis, MgCl ₂ is 1 mM, DNase I (manufactured by TAKARA) is 10 U / ml, and RNase I (manufactured by Nippon Gene) is 20 μg / ml. In addition, it was incubated at 37 ° C. for 2 hours. Next, in order to remove the protein, Proteinase K (manufactured by Takara Bio Inc.) was added to the liquid after removing the nucleic acid so as to be 3 U / ml, and incubated at 37 ° C. for 5 hours to carry out Proteinase K treatment.

After Proteinase K treatment, dialyzed with ultrapure water to remove low molecular weight substances. Next, L-PGA was adsorbed on an anion exchange resin (Q Sepharose Fast Flow, manufactured by GE Healthcare Bioscience), washed with 0.5 M NaCl aqueous solution, and then eluted with 1 M NaCl aqueous solution. The obtained solution was further dialyzed with ultrapure water, and the solution after dialysis was freeze-dried to obtain a sodium salt of L-PGA (hereinafter referred to as “L-PGA / Na salt”). In addition, the ultrapure water was produced with MilliQ (pure water production apparatus manufactured by Millipore).

[Production Example 2; Molecular weight analysis of poly-γ-L-glutamic acid-1]
The average molecular weight of the L-PGA · Na salt obtained in Production Example 1 was measured by GPC analysis. As a result, it was confirmed that Mw = 7,522,000, Mn = 3,704,000, and Mw / Mn = 2.031 (in pullulan conversion).

The GPC analysis was performed under the following conditions.
Apparatus: HLC-8220GPC (manufactured by Tosoh Corporation)
Column: TSKgel α-M (manufactured by Tosoh Corporation)
Flow rate: 0.6 ml / min
Eluent: 0.15M NaCl aqueous solution Column temperature: 40 ° C
Injection volume: 10 μl
Detector: Differential refractometer

[Production Example 3; Molecular weight analysis of poly-γ-L-glutamic acid-2]
In Production Example 1, after elution of a 1.0 M NaCl aqueous solution, L-PGA · obtained by performing the same operation as in Production Example 1 except that 1N HCl was used to adjust the pH to 2.0. The average molecular weight of the Na salt was measured by GPC analysis. As a result, it was confirmed that Mw = 2,888,000, Mn = 1,327,000, and Mw / Mn = 2.176 (in pullulan conversion). The GPC analysis in this production example was performed in the same manner as in Production Example 2.

[Production Example 4: Production of crosslinked poly-γ-L-glutamic acid]
A 5% aqueous solution of the L-PGA · Na salt obtained in Production Example 1 was prepared.

Next, the L-PGA / Na salt aqueous solution was bubbled with nitrogen for 3 minutes, and then 2 ml was taken into a 10 ml sample bottle with a lid and the lid was closed.

Next, the sample bottle was irradiated with γ-rays using a γ-ray irradiation device using cobalt 60 as a radiation source. Irradiation dose was 5 kGy. The product obtained after γ-ray irradiation was taken out of the sample bottle, excess water was drained with an 80-mesh wire mesh, and freeze-dried to obtain L-PGA crosslinked powder. The excess water contains uncrosslinked L-PGA, and the main purpose of draining is to remove uncrosslinked L-PGA.

Comparison between the present invention and the prior art [Example 1 and Comparative Example]
An emulsion having the following composition was prepared and used as Example 1 and Comparative Example.

Next, the conductance over time (manufactured by IBS Inc .: SKICON 200) was examined, and the moisturizing effect of the emulsions in Table 1 was evaluated. The evaluation method of the moisturizing effect of the emulsion is as follows.

<Test method for moisturizing effect>
Twenty women were divided into two groups each to form a panel. The first group was applied with the emulsion of Example 1, and the second group was applied with the emulsion of a comparative example. The conductance over time was measured to evaluate the moisturizing effect. The results are shown in Table 2.

From the results in Table 2, the emulsion (Example 1) containing poly-γ-L-glutamic acid and silicone oil used in the present invention was the same as the emulsion containing the usual hyaluronic acid and silicone oil (Comparative Example). It turns out that it has the moisturizing effect excellent in stability.

<Test method for usability test>
When measuring the moisturizing effect of the panel, the feeling of use was evaluated with regard to skin familiarity and stickiness. The evaluation criteria for the feeling of use are as follows. The results are shown in Table 3.

[Evaluation criteria for usability]
○: Skin familiarity is good △: Neither can be said ×: Skin familiarity is bad ○: Not sticky △: Neither can be said ×: Sticky

From the results of Table 3, the emulsion (Example 1) containing poly-γ-L-glutamic acid and silicone oil is excellent in affinity to the skin (skin familiarity), and the stickiness of hyaluronic acid is remarkably improved by silicone oil. You can see that On the other hand, in the case of the emulsion (comparative example) in which normal hyaluronic acid and silicone oil are blended, it is understood that the familiarity with the skin is inferior to that of Example 1 and the stickiness is not improved. Furthermore, the effect of the emulsions of Example 1 and Comparative Example was confirmed by a use test.

<Test method of usage test>
In the use test, 20 women were divided into 2 groups each and used as a panel. In the first group, the emulsion of Example 1 and in the second group, the emulsion of the comparative example was applied twice daily in the morning and at night, and an appropriate amount after face washing was applied to the face for 2 weeks to moisturize the skin. The effectiveness of each of the three items of elasticity and moisture of the next morning was judged. The results are shown in Table 4.

As is clear from the results in Table 4, the emulsion (Example 1) containing poly-γ-L-glutamic acid and silicone oil was similar to the emulsion (comparative example) containing ordinary hyaluronic acid and silicone oil. It had excellent effects on moisture of the skin, firmness of the skin, and moisture of the next morning.

Formulation of poly-γ-L-glutamic acid and silicone oil [Test Examples 1 to 4]
Emulsions with various compositions shown in Table 5 were prepared and used as Test Examples 1 to 4. The manufacturing method is the same as in Example 1 and the comparative example.

<Moisturizing effect test>
Next, 40 women were divided into 4 groups each to form panels, and the latexes of Test Examples 1 to 4 were applied to the first group to the fourth group, respectively. The conductance over time was measured to evaluate the moisturizing effect. The results are shown in Table 6.

From the results of Table 6, the emulsion containing only silicone oil (Test Example 3) or the emulsion containing only poly-γ-L-glutamic acid (Test Example 4) was not mixed with both emulsions (Test Example 2). Compared to the above, there is a slight moisturizing effect, but it cannot be avoided that the moisturizing effect decreases with time. On the other hand, it can be seen that the emulsion (Test Example 1) containing poly-γ-L-glutamic acid and silicone oil dramatically increases the aging stability of the moisturizing effect.

<Test of feeling of use>
At the time of measuring the moisturizing effect of the panel, the feeling of use was evaluated according to the following evaluation criteria with respect to skin familiarity and stickiness. The results are shown in Table 7.

[Evaluation criteria for usability]
○: Skin familiarity is good: Neither can be said ×: Skin familiarity is bad ○: Not sticky: Neither can be said ×: Sticky

From the results in Table 7, the emulsion containing only poly-γ-L-glutamic acid (Test Example 4) was compared with the emulsion containing no poly-γ-L-glutamic acid or silicone oil (Test Example 2). It turns out that it has quite stickiness. On the other hand, it can be seen that the emulsion containing only silicone oil (Test Example 3) has the same degree of skin familiarity and is not as good as Test Example 2. On the other hand, it can be seen that the emulsion (Test Example 1) containing both poly-γ-L-glutamic acid and silicone oil is well-familiar with the skin and has little stickiness. Therefore, it can be seen that by combining poly-γ-L-glutamic acid and silicone oil, it is possible to obtain a skin external preparation with good skin fit and no stickiness.

Blending amount of poly-γ-L-glutamic acid [Test Examples 5 to 10]
Emulsions having various compositions with varying amounts of poly-γ-L-glutamic acid shown in Table 8 were prepared and designated as Test Examples 5 to 10. The manufacturing method is the same as in Example 1 and the comparative example. Moreover, the moisturizing effect and usability test of the emulsions of the above Test Examples 5 to 10 were performed, and the results are shown in accordance with the compositions in Table 8. The test method and evaluation criteria are in accordance with Test Examples 1 to 4.

As is clear from the results in Table 8, the emulsion (Test Examples 6 to 9) having a poly-γ-L-glutamic acid content of 0.0001 to 10% by weight is excellent in moisturizing effect and has good skin familiarity. You can see that there is no stickiness. On the other hand, the emulsion containing less than 0.0001% by weight of poly-γ-L-glutamic acid (Test Example 5) has no stickiness, but the moisturizing effect is remarkably lowered and the skin conformity is deteriorated. Recognize. Moreover, it turns out that stickiness becomes strong in the emulsion (Test Example 10) in which the blending amount of poly-γ-L-glutamic acid exceeds 10% by weight.

Compounding amount of silicone oil [Test Examples 11 to 15]
Various emulsions with different amounts of silicone oil shown in Table 9 were prepared and used as Test Examples 11 to 15. The manufacturing method is the same as in Example 1 and the comparative example. Moreover, the moisturizing effect and usability test of the emulsions of Test Examples 11 to 15 were performed, and the results are shown in accordance with the compositions in Table 9. The test method and evaluation criteria are in accordance with Test Examples 1 to 4.

As is clear from the results in Table 9, it is understood that the emulsions (Test Examples 12 to 15) having a silicone oil content of 0.1% by weight or more are excellent in moisturizing effect and have no stickiness. On the other hand, it can be seen that the emulsion containing less than 0.1% by weight of the silicone oil (Test Example 11) has an extremely low moisturizing effect and is sticky.

Therefore, it can be seen that there is no effect unless the blending amount of the silicone oil is 0.1% by weight or more. It can also be seen that there is no problem with the upper limit of the amount of silicone oil up to at least 60% by weight.

Weight ratio of poly-γ-L-glutamic acid and silicone oil [Test Examples 16 to 20]
Various emulsions having different blending weight ratios of poly-γ-L-glutamic acid and silicone oil shown in Table 10 were prepared and used as Test Examples 16 to 20. The manufacturing method is the same as in Example 1 and the comparative example. Moreover, the moisturizing effect and usability (skin familiarity, stickiness) of the emulsions of Test Examples 16 to 20 were tested, and the results are shown in accordance with the compositions shown in Table 10. The test method and evaluation criteria are in accordance with Test Examples 1 to 4.

From the results in Table 10, the emulsions (Test Examples 17 to 19) having a blending weight ratio of poly-γ-L-glutamic acid and silicone oil of 1/1 to 1/40000 are well-familiar and have no stickiness. Recognize. On the other hand, it can be seen that the emulsion (Test Examples 16 and 20) having a blended weight ratio deviating from this ratio cannot obtain the excellent usability of the present invention.

Next, in order to make the external preparation for skin of the present invention more specific, examples are further shown. In addition, a compounding quantity shows weight%. When evaluated according to Example 1, the skin external preparation of each Example showed the same excellent moisturizing effect and usability as Example 1.

[Example 2] Cream-production method-
A (oil phase) and B (aqueous phase) are each heated to 70 ° C. and completely dissolved. Add A to B and emulsify with an emulsifier. The emulsion was cooled using a heat exchanger to obtain a cream.

[Example 3] The oil phase part of emulsion A and the aqueous phase part of B are each heated to 70 ° C and completely dissolved. Add Phase A to Phase B and emulsify with an emulsifier. The emulsion was cooled using a heat exchanger to obtain an emulsion.

Example 4 A cream was obtained according to Cream Example 2.

[Example 5] Pack

-Manufacturing method-
(4), (7) and (8) were mixed and dissolved at room temperature, and (1), (2), (3) and (5), (6) and (9) were mixed and dissolved at 80 ° C. After stirring, the mixture was allowed to cool to room temperature to obtain a pack.

[Example 6] Solid powder foundation

-Manufacturing method-
To each of the components (1) to (8) mixed and pulverized, the components (9) to (14) were mixed, mixed and stirred, and molded into a container to obtain a solid powder foundation.

[Example 7] Lipstick

-Manufacturing method-
(13) to (14) are dispersed in (12) heated to 60 ° C., and (9) to (11) uniformly dissolved therein are added thereto, followed by thorough stirring. Separately, this was added to (1) to (8), which had been heated and dissolved, and stirred well. Further, (15) to (17) were added, dispersed and stirred, and then molded to obtain a lipstick.

The present invention provides a skin external preparation having a moisturizing effect excellent in stability over time by containing poly-γ-L-glutamic acid and / or a salt thereof, and silicone oil, and particularly excellent in usability. Can do. Furthermore, since the raw material cost is lower than that of conventional poly-γ-L-glutamic acid, it can be mass-produced, and can sufficiently withstand long-term use, it is expected to greatly contribute to the industry.

Claims (6)

Poly-γ-L-glutamic acid and / or salt thereof 0.0001 to 10% by weight and silicone oil 0.1 to 60% by weight, and poly-γ-L-glutamic acid and / or salt thereof and silicone An external preparation for skin, wherein the blending ratio by weight of oil is 1/1 to 1/40000. The poly-γ-L-glutamic acid is a poly-γ-L-glutamic acid cross-linked product characterized by having a cross-linked structure between poly-γ-L-glutamic acid molecules. Skin external preparation. The skin external preparation according to claim 1 or 2, wherein the average molecular weight of poly-γ-L-glutamic acid is 1,000,000 or more. The skin external preparation according to any one of claims 1 to 3, wherein the average molecular weight of poly-γ-L-glutamic acid is 2 million or more. The skin external preparation according to any one of claims 1 to 4, wherein the average molecular weight of poly-γ-L-glutamic acid is 3.5 million or more. The skin external preparation according to any one of claims 1 to 5, wherein the water absorption ratio of poly-γ-L-glutamic acid is 10 to 5000 times.