JP5382903B2 - Method for measuring degree of hair damage using keratin film - Google Patents

Description

  The present invention relates to a method for measuring the degree of hair damage using a keratin film, and more particularly to improvement of its diagnostic ability.

  Factors that damage hair include ultraviolet irradiation, air dust, dryer heat, combing friction, excessive hair washing, perms, use of dyes and hair dyes, and the like. In recent years, research on hair damage caused by various factors has been actively conducted, and it is required to measure the degree of damage. Among these, various methods have conventionally been proposed as methods for measuring the degree of hair damage by ultraviolet irradiation. Specifically, a method of measuring a decrease in fluorescence emission after binding a fluorescent dye compound to an amino group of a hair protein and exposing the dyed hair to ultraviolet rays (see, for example, Non-Patent Document 1), tensile strength The method of measuring the damage limit of hair and confirming the correlation with oxidation (for example, refer nonpatent literature 2) etc. are mentioned. However, although the former method uses a fluorescent dye and has high sensitivity, it cannot quantitate hair damage, and the latter method has a difference in tensile strength depending on the hair quality, and thus has a correlation with oxidation. Is not constant, and there is a concern about variation in results, and any measurement method still has problems.

  On the other hand, when focusing on the carbonyl group, which is one of the functional groups inside the hair, it has become clear from the research by Claude Dubief, L'Oreal, Clichy et al. (Cosmetics & Toiletries Vol.107, October, 1992) and a method for measuring the quantification of a carbonyl group using a fluorescent dye has been proposed (see, for example, Non-Patent Document 3). According to this method, a bleached hair sample was irradiated with ultraviolet light, then treated with a fluorescent dye compound, Fliorescein-5-thiosemicarbazide, bound to a carbonyl group, and washed with PBS (phosphate buffer pH 7.5). Then, the fluorescence brightness is measured, and the difference before and after the ultraviolet irradiation can be quantified as the degree of hair damage. However, even with this measurement method, the measured values tended to vary due to individual differences in hair caused by using the hair itself and PBS washing conditions. In addition, when measuring the effect of UV damage on cosmetic hair due to ultraviolet rays, it is difficult to apply UV absorber-containing cosmetics uniformly on the hair, and when measuring the effect, average many measurement samples. Was required and took time and effort.

  As a high-sensitivity measurement method that replaces the above-described method, a method for measuring the degree of hair damage by extracting hair protein from hair and analyzing it has been studied. 70 to 80% of hair is composed of protein, and several types of proteins having different characteristics and structures are intertwined in complex to form insoluble keratin and exist in a strong fiber state. Therefore, although various methods for separating and collecting hair proteins have been studied, problems remain regarding extraction efficiency, mixing of substances that interfere with analysis, and the like.

  As a solution to the above problem, the present inventors have already reported a method for extracting a keratin protein that is highly efficient and suitable for analysis in a state as it is (see, for example, Patent Document 1). That is, hair is treated with a specific urea compound in the presence of a reducing agent, and the microfibrin constituting the hair cortex site and the keratin protein in the matrix with the cell interstitial material are eluted and collected, and the residue after this elution is collected. The cuticle portion whose shape is maintained is collected from the above. Furthermore, the present inventors also provide a method for producing a molded article such as a film or a gel composed of a keratin protein collected by further improving this method (see, for example, Patent Document 2).

JP 2002-114798 A JP 2002-332357 A Journal Cosmetic Chemistry, 40, 287-296 (1989) Cosmetics & Toiletries Vol.105, December, 1990 Abstracts of 125th Annual Meeting of the Pharmaceutical Society of Japan, 30-0975, W112-07

  However, no report has yet been made on a method for measuring the degree of hair damage using a hair keratin film. Furthermore, the conventional methods for measuring the degree of damage to hair have complicated operations and have varied measurement values as described above. An object of the present invention is to provide a simple method for measuring the degree of damage to ultraviolet hair, in which variations in measured values are improved.

In order to achieve the above object, the present inventors have conducted extensive research on a method for measuring the degree of hair damage by ultraviolet rays using the keratin film, and as a result, by using a uniform keratin film that eliminates individual differences, The variation in measured values was improved, and a measurement method having an excellent correlation with the degree of hair damage by ultraviolet rays was found, and the present invention was completed.
That is, the present invention relates to the degree of hair damage caused by ultraviolet rays using a keratin film obtained by bringing a hair keratin protein solution obtained by dissolving hair with a protein denaturant and a reducing agent into contact with a developing solution and drying. A measurement method is provided.

In the measurement method, it is preferable that the protein denaturant is urea or thiourea.
In the measurement method, it is preferable that the developing solution is one or more selected from a perchloric acid solution, a guanidine hydrochloric acid solution, an acetic acid solution, and an acetic acid buffer.

The reducing agent is preferably one or more selected from 2-mercaptoethanol, dithiothreitol, and thioglycolic acid.
In the measurement method, it is preferable that the keratin film is obtained by mixing a developing solution into the hair keratin protein solution and injecting the mixed solution into water.
In the measurement method, it is preferable that the keratin film is obtained by injecting the hair keratin protein solution into a developing solution.
Furthermore, in the measurement method, it is preferable that the keratin film is obtained by injecting a developing solution into the hair keratin protein solution.
In the measurement method, it is preferable that the developing solution is an acetic acid solution.
In the measurement method, it is preferable that the developing solution is an acetic acid solution or an acetic acid buffer.

The method for measuring the degree of hair damage includes the following steps.
(I) Irradiate the keratin film with ultraviolet rays.
(II) The keratin film after ultraviolet irradiation is dyed and then washed.
(III) After the washed keratin film is dried, the fluorescence luminance or the fluorescence intensity is measured.

  According to the present invention, it is possible to measure the degree of hair damage that has no variation in measured values and has excellent correlation with hair damage caused by ultraviolet rays.

Hereinafter, preferred embodiments of the present invention will be described.
The method for measuring the degree of hair damage according to the present invention is particularly used for measuring the degree of damage to hair by sunlight ultraviolet rays and similar artificial UV irradiation. However, the factor of hair damage is not limited to this, and it can be used as a means for measuring changes in the hair state.
In the present invention, “hair” includes animal hair and feathers in addition to human hair. The measurement method according to the present invention can also be applied to nails and skin containing keratin protein.
First, the keratin film used in the method for measuring the degree of hair damage by ultraviolet rays according to the present invention will be described.

Preparation of Keratin Film A protein denaturant is used to extract a group of keratin proteins constituting the keratin film . The protein denaturant is preferably a urea compound, and examples thereof include urea, thiourea, and derivatives thereof. It is preferable to use one or more of these urea-based protein denaturants in combination. More preferably, urea and thiourea are mixed and used. When using a mixture of urea and thiourea, the mixing mass ratio is preferably 5: 1 to 1: 2. If the mixing ratio of thiourea is less than the above range, the protein denaturing action may be inferior, and if it exceeds the above range, the extraction rate of the keratin protein group tends to decrease.

The concentration of the protein denaturant in the hair sample treatment solution is preferably 30 to 70% by mass. If the amount is less than 30% by mass, the extraction rate of the keratin protein group tends to decrease, and even if it is used in excess of 70% by mass, the effect of improving the extraction rate by increasing the amount is not recognized. In some cases, the viscosity of the resin becomes high and the workability deteriorates. Here, the “hair sample treatment solution” means a hair keratin protein solution composed of a hair sample and a protein denaturant, and a mixed solution in the production process for extracting a keratin protein group, including a reducing agent described later.
As described above, by using a protein denaturant, it is possible to efficiently dissolve and extract a keratin protein group from hair under mild conditions.

In preparing the keratin film used in the present invention, a reducing agent is used in combination with the protein denaturing agent. Examples of the reducing agent include thioalcohols such as 2-mercaptoethanol, dithiothreitol, and thioglycolic acid. These 1 type (s) or 2 or more types can be used in combination.
By using a reducing agent in combination with the protein denaturant, the extraction rate of the keratin protein group can be further improved. This is because the protein modifier denatures the strong keratin fiber structure, and then the reducing agent efficiently dissociates the strong SS bond between the keratin proteins, and recombination hardly occurs in the hair sample treatment solution. It is thought to do.

When the reducing agent is used in combination with a protein denaturant, the hair sample treatment solution preferably contains 0.5 to 40% by mass, more preferably 1 to 20% by mass. However, it is preferably determined as appropriate depending on the solubility of the reducing agent used in the hair sample treatment solution.
When the concentration of the reducing agent is less than 0.5% by mass, there is a tendency that the strong reductive cleavage of the S—S bond between the keratin proteins is not sufficiently performed, and when the concentration exceeds 40% by mass. The solubility of the keratin protein group in the hair treatment solution may be deteriorated.

The treatment time for obtaining the hair keratin protein solution depends on the treatment temperature, but is preferably 1 to 4 days. Moreover, it is preferable that processing temperature is 20-60 degreeC. If the temperature is lower than 20 ° C., the reaction progresses slowly and the efficiency is poor. If the temperature exceeds 60 ° C., the hair sample treatment solution exhibits alkalinity, which causes side reactions such as peptide bond cleavage, substituent conversion, and crosslinking. There is a case.
The ratio of the hair sample to the hair sample treatment solution is preferably 1 to 100 mg hair sample / ml hair sample treatment solution.
After the keratin protein is sufficiently extracted from the hair sample treatment solution, the hair-extracted hair is removed by filtration to obtain a hair keratin protein solution.

In order to solidify or gel the hair keratin protein solution obtained by treating the hair sample using a protein denaturant and a reducing agent in combination and filtering it, the developing solution is contacted. By this solidification or gelation, the film is formed as a film having a form suitable for use in the method for measuring the degree of hair damage by ultraviolet rays according to the present invention.
Examples of the developing solution include a modifying agent solution obtained by mixing a modifying agent such as trichloroacetic acid, guanidine hydrochloride, perchloric acid, and derivatives thereof, and a solvent such as water, physiological saline, and lower alcohol, hydrochloric acid And acidic solutions composed of acidic substances such as sulfuric acid, acetic acid, phosphoric acid and salts thereof. These 1 type (s) or 2 or more types can be used. In the preparation of the keratin film used in the present invention, the developing solution is preferably one or more selected from a perchloric acid solution, a guanidine hydrochloric acid solution, an acetic acid solution, and an acetic acid buffer. Particularly preferred is an acetic acid solution or an acetic acid buffer (pH 4.0).

The concentration of the denaturant solution used as the developing solution is preferably 10 to 60% by mass. The concentration of the acidic solution used as the developing solution is preferably 10 to 500 mM.
The developing solution has an action of lowering the ionic strength of the hair keratin protein solution, thereby causing a decrease in the solubility of the protein denaturant and reducing agent in the hair sample treatment solution. As a result, the solubility of the keratin protein group was lowered, and the SS bond between the keratin proteins was dissociated and the SH bond was re-established. Protein solidification will proceed.

When preparing the keratin film used in the present invention, a post-cast method or a pre-cast method can be applied.
As a post-cast method, a container such as a petri dish is preliminarily filled with the developing solvent, and a hair keratin protein solution is cast thereon (forward method), or a container such as a petri dish to which a hair keratin protein solution is added in advance. In addition, a method of casting the developing solution (reverse method) may be mentioned.
The pre-cast method is a method in which a developing solvent is mixed with hair keratin protein in advance, and the mixed solution is cast into a container such as a petri dish filled with water.
In the present invention, a keratin film excellent in uniformity suitable for the method for measuring the degree of hair damage by ultraviolet rays according to the present invention can be prepared by applying any of the Post-cast method and the Pre-cast method. .
In particular, an acetic acid solution can be suitably used as a developing solvent used in the Pre-cast method. In the post-cast method, an acetate buffer is suitable as a developing solvent.
As the reducing agent, 2-mercaptoethanol is suitable for use in the Post-cast method, and dithiothreitol is suitable for use in the Pre-cast method.
The developing solution is preferably used in a mass ratio of 10 to 10,000 times that of the hair keratin protein solution. By bringing the developing solution into contact with the hair keratin protein solution within the above range, a thin film exhibiting an appropriate thickness can be prepared.

  The thin-film hair keratin protein molded product formed in the petri dish is washed with the developing solvent. The number of times of washing is not particularly limited, but is preferably about 1 to 5 times. After washing, the solution is removed, and the hair keratin protein molded product on the petri dish is dried to obtain a keratin film. The drying method is not particularly limited, and examples include drying by standing at room temperature free from dust.

  Some hair samples used for the preparation of keratin film contain a large amount of oil, and may be degreased before treatment. Examples of the degreasing method include treatment with a mixed solvent of chloroform and methanol, but other conventional methods may be used and are not particularly limited.

Method for measuring the degree of hair damage by ultraviolet rays For the measurement of the degree of hair damage by ultraviolet rays according to the present invention, the aforementioned keratin film is used as a measurement specimen. The measuring method includes the following steps (I) to (III).
(I) Irradiate the keratin film with ultraviolet rays.
(II) The keratin film after ultraviolet irradiation is dyed and then washed.
(III) After the washed keratin film is dried, the fluorescence luminance or the fluorescence intensity is measured.
Hereinafter, each process is explained in full detail.

  In step (I), the surface half of the keratin film prepared using the hair to be measured is covered with a material that does not transmit ultraviolet rays, such as aluminum foil, and then irradiated with ultraviolet rays. Although the ultraviolet irradiation time at this time is not specifically limited, 1 day-2 years are converted into the irradiation time in an experimental system in consideration of the ultraviolet exposure of the hair in daily life and the life cycle of the hair. At this time, the keratin film is preferably fixed to a container such as a petri dish, but is not limited thereto. Half of the surface of the keratin film is irradiated with ultraviolet light, and the other half is not irradiated with ultraviolet light.

該化合物のヒドラジン基が、毛髪ケラチン蛋白質が有するカルボニル基（アルデヒド）と反応することにより、５−ＦＴＳＣが毛髪ケラチンタンパク質に結合される。毛髪ケラチン蛋白質が有するカルボニル基は、紫外線照射により増加することが既に知られている（Cosmetics＆Toiletries Vol.107, October, 1992）。従って、紫外線照射されたケラチンフィルム部分と、紫外線未照射のケラチンフィルム部分とでは、５−ＦＴＳＣとの結合割合に相違が生じる。その結果、後の工程における蛍光輝度の測定において数値に差が現れ、毛髪損傷度を確認することが可能となる。 In the step (II), the keratin film after ultraviolet irradiation is dyed with a fluorescent dye compound. An example of the fluorescent dye compound is Fluorescein-5-thiosemicarbazide (hereinafter referred to as 5-FTSC), and this compound is preferably used in the present invention. In addition, dansyl hydrazine having a hydrazine group can also be used.
The chemical structural formula of 5-FTSC is shown below.

By reacting the hydrazine group of the compound with a carbonyl group (aldehyde) of the hair keratin protein, 5-FTSC is bound to the hair keratin protein. It is already known that the carbonyl group of hair keratin protein is increased by ultraviolet irradiation (Cosmetics & Toiletries Vol.107, October, 1992). Therefore, a difference occurs in the binding ratio with 5-FTSC between the keratin film portion irradiated with ultraviolet rays and the keratin film portion not irradiated with ultraviolet rays. As a result, a difference appears in the numerical value in the measurement of the fluorescence luminance in the subsequent process, and it becomes possible to confirm the degree of hair damage.

  First, a staining solution is prepared for staining. 5-FTSC is dissolved in a dimethyl sulfoxide solution to prepare a 5 mM 5-FTSC solution. Next, the previously adjusted 5 mM 5-FTSC solution was dissolved in 0.1 M MES (2-Morpholinoethanesulfonic acid, monohydrate) adjusted to pH 5.5 using sodium hydroxide, and 20 μM 5-FTSC / A 0.1 M MES-NA (pH 5.5) staining solution is prepared. In the staining method, 20 μM of 5-FTSC / 0.1 M MES-NA (pH 5.5) staining solution is poured onto a petri dish containing a keratin film and allowed to stand at room temperature for 15 minutes. After the dyeing is sufficiently performed, a washing operation is performed to remove the staining solution. After discarding the staining solution from the petri dish, first, a 2 × SSC-0.1% SDS solution is poured and allowed to stand at room temperature for 5 minutes. Change the cleaning solution and repeat again. Next, 0.2 × SSC-0.1% SDS solution is poured and allowed to stand at 50 ° C. for 20 minutes. Change the cleaning solution and repeat again. Then, distilled water is poured and allowed to stand at room temperature for 2 minutes. Repeat 6 times in total, changing the distilled water. ) It is preferable that all the steps of preparing, dyeing and washing the staining solution are performed under light shielding.

In the step (III), the keratin film washed in the previous step is dried. The drying method is not particularly limited, and examples thereof include placing in a desiccator and drying under reduced pressure.
After sufficiently drying the keratin film, the fluorescence brightness is measured. As the measuring device, for example, an epifluorescence microscope or a stereoscopic fluorescence microscope is used. When the target object is irradiated with excitation light of 490 nm, fluorescence of 520 nm is emitted from the fluorescent material, and this is captured as an image. This image is processed by image analysis software, and an average luminance is obtained from a luminance histogram in pixel units relating to the color development of the fluorescent dye. The degree of hair damage can be quantified as the luminance of irradiated hair minus the luminance of unirradiated hair. Alternatively, the fluorescence intensity can be measured with a fluorescence spectrophotometer, and the hair damage degree can be similarly expressed.

FIG. 1 illustrates the result of fluorescence luminance. The method for preparing the keratin film used is as follows.
(Preparation of keratin film 1)
A hair sample treatment solution is obtained by immersing 600 mg of hair of a 15-year-old woman in a mixed solution containing 30% by weight of urea, 20% by weight of thiourea, 5% by weight of dithiothreitol, and 8 ml of 25 mM Tris-HCl buffer (pH 8.5). This was held at 50 ° C. for 4 days to obtain a hair keratin protein solution. The powder-extracted hair was removed from the solution by filtration to obtain a hair keratin protein solution. To this protein solution 3.5 mg, 6 ml of 100 mM acetic acid aqueous solution was added and mixed, and this mixed solution was gently cast into a petri dish (diameter 35 mm) filled with water. After solidification, the developing solution containing distilled water was changed several times, and the solution in the gel was replaced with distilled water. Finally, distilled water was removed, and it was sufficiently dried in a box containing silica gel to obtain the desired keratin film.

Using the obtained keratin film, fluorescence luminance was measured according to the following experimental method.
(experimental method)
(I) The keratin film is irradiated with artificial sun (Solar simulator, 15 mW / cm ² : 290 to 390 nm) for 10 minutes to 4 hours. At that time, the surface half of the film is shielded with aluminum foil so that light does not strike.
(II) Dye the keratin film after UV irradiation. 5-FTSC is dissolved in a dimethyl sulfoxide solution to prepare a 5 mM 5-FTSC solution. Next, the previously prepared 5 mM 5-FTSC solution was dissolved in 0.1 M MES (2-Morpholinoethanesulfonic acid, monohydrate) adjusted to pH 5.5 using sodium hydroxide, and 20 μM 5-FTSC / A 0.1 M MES-NA (pH 5.5) staining solution is prepared. In the staining method, 20 μM of 5-FTSC / 0.1 M MES-NA (pH 5.5) staining solution is poured onto a petri dish containing a keratin film and allowed to stand at room temperature for 15 minutes. After the dyeing is sufficiently performed, a washing operation is performed to remove the staining solution. After discarding the staining solution from the petri dish, first, a 2 × SSC-0.1% SDS solution is poured and allowed to stand at room temperature for 5 minutes. Change the cleaning solution and repeat again. Next, 0.2 × SSC-0.1% SDS solution is poured and allowed to stand at 50 ° C. for 20 minutes. Change the cleaning solution and repeat again. Then, distilled water is poured and allowed to stand at room temperature for 2 minutes. Repeat 6 times in total, changing the distilled water. ) All the steps of preparing, dyeing and washing the staining solution are performed in the dark.
(III) After the washed keratin film is dried in a desiccator, a fluorescence image is obtained with a stereoscopic fluorescence microscope, and then the fluorescence luminance is measured.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to the following examples.
First, film forming properties, durability and water resistance, dyeability, and film opacity were evaluated for suitability as a film used for measurement. Evaluation methods and evaluation criteria are as follows.

(1) Film forming property (evaluation method)
It is visually judged whether the film is prepared thinly and uniformly.
(Evaluation criteria)
○: A thin and uniform film spreads throughout the petri dish. Δ: The film does not spread across the petri dish, and the film spreads unevenly. ×: The film does not spread out and is solidified.

(2) Opacity of film (evaluation method)
Visually determine if the film is not transparent.
(Evaluation criteria)
○: The film is not transparent (opaque).
Δ: The film is translucent.
X: The film is transparent.

(3) Durability (Evaluation method)
Visually determine whether the film is cracked or perforated during light irradiation / dyeing / washing.
(Evaluation criteria)
○: No cracks or holes are seen in the film.
(Triangle | delta): A fine crack and a hole are seen.
X: A crack and a hole are seen in the whole film.

(4) Water resistance (evaluation method)
Visually determine whether the film has been peeled off or turned over during dyeing / washing.
(Evaluation criteria)
○: The film is not peeled off or turned over from the petri dish.
Δ: The outside of the film is slightly turned over.
X: The film has peeled off from the petri dish.

(5) Dyeability (evaluation method)
In the fluorescence image acquired with the stereoscopic fluorescence microscope, it is confirmed whether the fluorescence luminance increases with the increase of the irradiation time.
(Evaluation criteria)
(Double-circle): The fluorescence brightness | luminance increases obviously with the increase in irradiation time.
○: Fluorescence luminance increases with increasing irradiation time.
(Triangle | delta): The fluorescence brightness | luminance has increased slightly with the increase in irradiation time.
X: A change is not seen in fluorescence luminance with the increase in irradiation time.

Various keratin films obtained by the constitution shown in Table 1 below were evaluated according to the above evaluation items. The evaluation results are shown in Table 1.
In addition, the various keratin films in Table 1 were prepared by the following preparation methods.
(Keratin film preparation method 1: Pre-cast)
600 mg of hair sample is immersed in a mixed solution containing 8 ml of urea and thiourea, a reducing agent, 25 mM Tris-HCl buffer (pH 8.5) to obtain a hair sample treatment solution, which is kept at 50 ° C. for 4 days. A hair keratin protein solution was obtained. The powder-extracted hair was removed from the solution by filtration to obtain a hair keratin protein solution. To 3.5 mg of this protein solution, 6 ml of a developing solvent was added and mixed, and this mixed solution was gently cast into a petri dish (diameter 35 mm) filled with distilled water. After solidification, the developing solution containing distilled water was changed several times, and the solution in the gel was replaced with distilled water. Finally, distilled water was removed, and it was sufficiently dried in a box containing silica gel to obtain the desired keratin film.

＊１：還元剤a；２−メルカプトエタノール、b；ジチオスレイトール
＊２：GHA；グアニジン塩酸溶液、PCA；過塩素酸溶液 (Keratin film preparation method 2: Post-cast)
600 mg of hair sample is immersed in a mixed solution containing 8 ml of urea and thiourea, a reducing agent, 25 mM Tris-HCl buffer (pH 8.5) to obtain a hair sample treatment solution, which is kept at 50 ° C. for 4 days. A hair keratin protein solution was obtained. The powder-extracted hair was removed from the solution by filtration to obtain a hair keratin protein solution. This protein solution (3.5 mg) was gently cast into a petri dish (35 mm in diameter) filled with 6 ml of a developing solvent. After solidification, the developing solution containing distilled water was changed several times, and the solution in the gel was replaced with distilled water. Finally, distilled water was removed, and it was sufficiently dried in a box containing silica gel to obtain the desired keratin film.

* 1: Reducing agent a; 2-mercaptoethanol, b; dithiothreitol * 2: GHA; guanidine hydrochloride solution, PCA; perchloric acid solution

As is clear from the results of Table 1 above, when no reducing agent is added during the preparation of the keratin film (Comparative Example 1), or when the protein denaturant is only urea (Comparative Example 2), the film-forming property is slightly increased. Durability was inferior, and this tended to affect water resistance and dyeability. Moreover, in the sample of the comparative example, the film was transparent. When the keratin film is transparent, it is considered that in the measurement of the degree of hair damage, the change in hair protein due to UV irradiation becomes non-uniform.
Therefore, in the measurement method of the present invention, it is preferable that urea and thiourea are blended as protein denaturing agents, and hair keratin protein is dissolved and extracted with a reducing agent.

  Furthermore, more suitable reducing agents and developing solvents were studied for each method for preparing keratin films according to the present invention. The evaluation was performed according to the above test for the preparation method of the keratin film due to the opacity of the film. The results are shown in Table 2 below.

＊１：還元剤a；２−メルカプトエタノール、b；ジチオスレイトール

* 1: Reducing agent a; 2-mercaptoethanol, b: dithiothreitol

From the above results, in the production of the keratin film, changes in the opacity of the film were recognized depending on the type of the developing solvent. That is, it is recognized from the comparison with Examples 5 and 6 and Test Examples 1 and 2 that an acetic acid buffer solution is suitable as a developing solvent for the Post-cast method and an acetic acid solution is suitable for the Pre-cast method.
Further, from the comparison with Examples 5 and 6 and Test Examples 3 and 4, when 2-mercaptoethanol is used as the reducing agent, the post-cast method is preferably applied, and the di-threitol is suitable for the pre-cast method. It is recognized that
Therefore, it was recognized that the suitability of the keratin film for use in the method for measuring the degree of hair damage differs depending on the reducing agent.

Next, a study was conducted to investigate whether UV hair damage measurement methods using keratin films can be applied to human hair with different external shapes, damaged hair, and animal hair as well as human hair. did. The hair sample used was selected from human female straight hair, eyelashes, perm-treated hair and wool. Each hair sample was used to prepare each keratin film as follows.
(Preparation of various keratin films)
Each hair sample 600 mg was immersed in a solution containing 30% by weight urea, 20% by weight thiourea, 5% by weight 2-mercaptoethanol, 8 ml of 25 mM Tris-HCl buffer (pH 8.5) to obtain a hair sample treatment solution, This was kept at 50 ° C. for 4 days to obtain a hair keratin protein solution. The powder-extracted hair was removed from the solution by filtration to obtain a hair keratin protein solution. 3.5 mg of this protein solution was gently cast into a petri dish filled with 6 ml of 100 mM acetate buffer (pH 4.0). After solidification, the developing solution containing distilled water was changed several times, and the solution in the gel was replaced with distilled water. Finally, distilled water was removed, and it was sufficiently dried in a box containing silica gel to obtain various keratin films.

Next, using the various keratin films obtained, the measurement of the degree of hair damage by ultraviolet rays was carried out by the following measurement of fluorescence luminance. The experimental method is as follows.
(Measurement method of fluorescence luminance)
(I) The keratin film is irradiated with artificial sun (Solar simulator, 15 mW / cm ² : 290 to 390 nm) for 10 minutes to 4 hours. At that time, the surface half of the film is shielded with aluminum foil so that light does not strike.
(II) Dye the keratin film after UV irradiation. 5-FTSC is dissolved in a dimethyl sulfoxide solution to prepare a 5 mM 5-FTSC solution. Next, the previously prepared 5 mM 5-FTSC solution was dissolved in 0.1 M MES (2-Morpholinoethanesulfonic acid, monohydrate) adjusted to pH 5.5 using sodium hydroxide, and 20 μM 5-FTSC / A 0.1 M MES-NA (pH 5.5) staining solution is prepared. In the staining method, 20 μM of 5-FTSC / 0.1 M MES-NA (pH 5.5) staining solution is poured onto a petri dish containing a keratin film and allowed to stand at room temperature for 15 minutes. After the dyeing is sufficiently performed, a washing operation is performed to remove the staining solution. After discarding the staining solution from the petri dish, first, a 2 × SSC-0.1% SDS solution is poured and allowed to stand at room temperature for 5 minutes. Change the cleaning solution and repeat again. Next, 0.2 × SSC-0.1% SDS solution is poured and allowed to stand at 50 ° C. for 20 minutes. Change the cleaning solution and repeat again. Then, distilled water is poured and allowed to stand at room temperature for 2 minutes. Repeat 6 times in total, changing the distilled water. ) All the steps of preparing, dyeing and washing the staining solution are performed in the dark.
(III) After the washed keratin film is dried in a desiccator, a fluorescence image is obtained with a stereoscopic fluorescence microscope, and then the fluorescence luminance is measured.

  As is clear from the results in Table 2 above, the hair used for the preparation of the keratin film can be adjusted from any hair or animal hair regardless of origin, appearance, treatment, and the like. The damage degree measurement method can be applied.

It is the figure which showed the measurement result of the fluorescence brightness | luminance of the keratin film prepared from the hair sample which received the hair damage by the ultraviolet-ray.

Claims (10)

  A method for measuring the degree of hair damage caused by ultraviolet rays using a keratin film obtained by bringing a hair keratin protein solution obtained by dissolving hair with a protein denaturant and a reducing agent into contact with a developing solution and drying the solution.   The method for measuring the degree of hair damage according to claim 1, wherein the protein denaturant is urea or thiourea.   The method for measuring the degree of hair damage according to claim 1 or 2, wherein the developing solution is one or more selected from a perchloric acid solution, a guanidine hydrochloric acid solution, an acetic acid solution, and an acetic acid buffer. A method for measuring the degree of hair damage caused by ultraviolet rays.   The method for measuring the degree of hair damage according to any one of claims 1 to 3, wherein the reducing agent is one or more selected from 2-mercaptoethanol, dithiothreitol, and thioglycolic acid. A method for measuring the degree of hair damage caused by ultraviolet rays.   The method for measuring the degree of hair damage according to any one of claims 1 to 4, wherein the keratin film is obtained by mixing a developing solution into the hair keratin protein solution and injecting the mixed solution into water. A method for measuring the degree of hair damage caused by ultraviolet rays.   5. The method for measuring the degree of hair damage according to any one of claims 1 to 4, wherein the keratin film is obtained by injecting the hair keratin protein solution into a developing solution. Degree measurement method.   The method for measuring the degree of hair damage according to any one of claims 1 to 4, wherein the keratin film is obtained by injecting a developing solution into the hair keratin protein solution. Degree measurement method.   6. The method for measuring the degree of hair damage according to claim 5, wherein the developing solution is an acetic acid solution.   8. The method for measuring the degree of hair damage according to claim 6, wherein the developing solution is an acetic acid solution or an acetate buffer. The hair damage degree measuring method according to claim 1, comprising the following steps.
(I) Irradiate the keratin film with ultraviolet rays.
(II) The keratin film after ultraviolet irradiation is dyed and then washed.
(III) After the washed keratin film is dried, the fluorescence luminance or the fluorescence intensity is measured.

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