JP7109935B2 - Methods for evaluating hair damage and methods for testing compounds or compositions - Google Patents

Description

The present invention relates to a hair damage assessment method for assessing the degree of hair damage and a method for testing a compound or composition using the assessment method.

Hair is damaged by light such as ultraviolet rays, heat from hair dryers and curling irons, brushing, and the like in daily life. Hair is also damaged in oxidative hair dyeing treatments involving oxidation reactions, reduction reactions, and permanent waving and curly hair straightening treatments involving oxidation reactions.

Evaluation of hair damage is considered useful for research and development of hair and hair compositions. The method disclosed in Patent Document 1 focuses on a thiol group (SH group) generated by brushing, perming, etc. as an index of damage, and after modifying the SH group with a fluorescent substance, the fluorescence on the hair surface is confirmed. Yes (claim 1, example), the method disclosed in Patent Document 2 uses permanent treatment, bleaching, oxidation hair dye treatment, combing, heat treatment, exposure to ultraviolet rays, hypochlorous acid in the pool as an indicator of damage. Focusing on the carbonyl group that is generated by exposure to chemicals, etc., the fluorescence of the hair surface is confirmed after modifying (acting and binding to) the carbonyl group with a fluorescent substance. In addition, Patent Document 3 states that there is a correlation between damage to hair caused by ultraviolet rays and a predetermined keratin film obtained after dissolving hair, and damage received from ultraviolet rays, and carbonyl rays produced in the keratin film by ultraviolet rays. A device for confirming the fluorescence of a fluorescent substance reacted with a base is disclosed (claim 1, claim 10, paragraphs 0008 and 0026).

JP-A-8-178920 WO2005/57211 JP 2008-180709 A

By the way, the evaluation methods disclosed in the above patent documents focus on thiol groups or carbonyl groups. We can expect development. In addition, since the above-mentioned evaluation method confirms fluorescence appearing on the surface of hair or keratin film, it cannot be said to be suitable for evaluation including internal damage such as hair.

In view of the above circumstances, the present invention provides a hair damage evaluation method that can target functional groups other than thiol groups and carbonyl groups in hair damage and is suitable for evaluation including damage inside the hair, and the method. It is intended to provide methods for testing compounds or compositions for use.

The method for evaluating hair damage according to the present invention includes the amount of cysteic acid (I) in the hydrolyzate (I) obtained by hydrolyzing the reference hair, and the hydrolyzate (I) obtained by hydrolyzing the comparative hair. The amount of cysteic acid (II) in II) is compared. According to the comparison, for example, evaluation of hair damage by age, evaluation of hair root and hair tip damage can be performed.

In the method for evaluating hair damage according to the present invention, it is preferable that the reference hair and/or the comparative hair are placed under a damage imparting environment. If such hair is targeted, for example, evaluation of hair damage depending on whether or not it is placed in a damage-imparting environment, and evaluation of hair damage when the conditions of the damage-imparting environment in which the reference hair and the comparative hair are placed are the same. It is possible to evaluate hair damage when the conditions of the damage-imparting environment in which the evaluation, reference hair and comparative hair are placed are different.

Said damage is performed by light, for example. By irradiation or exposure to light, cysteic acid is produced not only on the hair surface but also inside the hair. This is a finding that has not been clarified so far.

One or more compounds or compositions may be contacted with the reference hair and/or the comparison hair prior to exposure to the damaging environment. This contact makes it possible, for example, to confirm and compare inhibitory effects on hair damage caused by compounds and compositions. From a different point of view, it becomes a test method for a compound or composition for judging the presence or absence of an effect of suppressing hair damage and the superiority of the composition.

According to the method for evaluating hair damage according to the present invention, since the amount of cysteinic acid in the hydrolyzate obtained from each of the reference hair and the comparative hair is compared, hair damage can be evaluated without using thiol groups or carbonyl groups. In addition, evaluation including damage inside the hair becomes possible.

In addition, according to the test method for the compound or composition according to the present invention, reference hair and comparative hair before hydrolysis to obtain hydrolyzate (I) and hydrolyzate (II) are placed under a damaging environment. Since the compound or composition is brought into contact with reference hair and/or comparative hair before being placed in the environment, it is possible to confirm the damage-inhibiting effect of the compound or composition and judge its superiority or inferiority.

Examples of infrared spectra of reference hair a(-) and comparative hair a(...) in Reference Example A. 3 is a graph showing the average values of I _1065-1030 /I _1600-1470 of reference hair a and comparative hair a in Reference Example A. FIG. A graph showing the average values of I _1065-1030 /I _1600-1470 at each measurement point in the radial direction of reference hair a and comparative hair a in Reference Example A. FIG. Results of cysteic acid relative intensity mapping measurement of reference hair a and comparative hair a in Reference Example A. FIG. Results of cysteic acid relative intensity mapping measurement of reference hair b and comparative hair b in Reference Example B. FIG.

The present invention will be described below based on the embodiments of the present invention.
In the hair damage evaluation method of the present embodiment, the amount (I) of cysteic acid in the hydrolyzate (I) obtained by hydrolyzing the reference hair and the hydrolyzate obtained by hydrolyzing the comparative hair Compare with the amount of cysteic acid (II) in (II). When hair is exposed to oxidative conditions, it is damaged and cysteic acid is generated in the constituent amino acids of hair. Evaluation of damage becomes possible.

The reference hair and the comparative hair are hairs to be compared, and the purpose of comparison may be arbitrarily set. The purposes are comparison by age (for example, comparison between twenties and fifties), comparison of hair parts (for example, comparison between roots and ends), and the like. In addition, if only the reference hair, only the comparative hair, or both the reference hair and the comparative hair are arbitrarily placed in the damage imparting environment before hydrolysis, the hair damage caused by the presence or absence of being placed in the damage imparting environment can be evaluated. Evaluation, evaluation of hair damage when the conditions of the damage imparting environment to be placed are different, evaluation of hair damage when the conditions of the damage imparting environment to be placed are the same. comparison) can be performed.

When the hair is placed in a damage-imparting environment, the damage is applied, for example, by light irradiation, light exposure, etc.; heat from a dryer or curling iron; oxidative hair dyeing treatment, permanent wave treatment, composition for hair straightening treatment, etc. contact with; It has been found that when the damage is caused by light, the ratio of cysteic acid in the constituent amino acids inside the hair unexpectedly increases. This finding is based on the results obtained by comparing the case where the cut surface of the hair in the circumferential direction (the cut surface that is substantially perpendicular to the axis of the hair) is irradiated with ultraviolet rays, which is a kind of light, and when it is not irradiated with ultraviolet rays. It was obtained for the first time by analyzing the infrared absorption spectrum data obtained using BL43IR of -8.

If the reference hair alone, the comparison hair alone, or both the reference hair and the comparison hair are contacted with one or more compounds or compositions prior to exposure to the damaging environment, the compound or composition It is possible to confirm the effect of suppressing hair damage by substances, compare the effect of suppressing hair damage between compounds, compare the effect of suppressing hair damage between compositions, and compare the effect of suppressing hair damage between compounds and compositions.

As described above, in order to obtain the hydrolyzate (I) and the hydrolyzate (II), the reference hair is hydrolyzed and the comparative hair is hydrolyzed. The advantage is that it becomes easy to perform an average damage evaluation for the entire hair to be evaluated.). Before this hydrolysis, the reference hair and the comparison hair are usually washed.

The hydrolysis of reference hair and comparative hair in this embodiment uses known methods for hydrolyzing hair. For example, there is a method of heating reference hair and comparative hair in an acidic aqueous solution mixed with hydrochloric acid or the like, and this method is suitable because hydrochloric acid can be easily removed from hydrolyzate (I) and hydrolyzate (II). is. Moreover, in order to prevent bumping, the hydrolysis is preferably performed, for example, in a sealed container under reduced pressure.

The amount of cysteic acid (I) and the amount of cysteic acid (II) in the present embodiment are determined by a known cysteic acid determination method. For example, amino acid analysis using high performance liquid chromatography. The quantified amount of cysteic acid (I) and the amount of cysteic acid (II) are compared, and it is judged that the larger the value, the greater the hair damage.

Hereinafter, the present invention will be described in detail based on examples, etc., but the present invention is not limitedly interpreted based on the description of these examples.

(Example A)
Determination of cysteic acid content (Ia) in hydrolyzate (Ia) obtained by hydrolysis a of reference hair a, and cysteine in hydrolyzate (IIa) obtained by hydrolysis a of comparative hair a The amount of acid (IIa) was quantified. Comparative hair a was subjected to damaging environment a prior to hydrolysis. Details are as follows.

Reference hair a and comparison hair a
Black hair with no chemical treatment history such as oxidative hair dyeing was collected from four Japanese women in their twenties, immersed in a 1% by mass sodium lauryl sulfate aqueous solution for 30 minutes, washed with water, and dried. The washed hair was used as reference hair a and comparative hair a.

Damage imparting environment a
For 1 g of comparative hair a, an ultraviolet irradiator ("XT-750L" manufactured by Suga Test Instruments Co., Ltd.) is used, and the total amount of ultraviolet A and B waves is 3,000 kJ/ ^m2 on average per day. irradiated for days. This 10-day UV irradiation was used as a damage imparting environment a.

hydrolysis a
Reference hair a and comparison hair a were washed with chloroform, dried and then chopped. About 3 mg each of the chopped reference hair a and comparative hair a and 50 μl of 6 mol/L hydrochloric acid were placed in a glass tube, which was then sealed while reducing the pressure inside. Then, the sealed glass tube was left in a constant temperature heating furnace set at 110° C. for 16 hours to perform hydrolysis a.

Recovery of hydrolyzate (Ia) and hydrolyzate (IIa) After hydrolysis, the glass tube was opened, and hydrochloric acid was immediately distilled off with nitrogen gas, and then the dried hydrolyzate (Ia) and hydrolyzate were collected. Product (IIa) was recovered.

Determination of Cysteic Acid Amount (Ia) and Cysteic Acid Amount (IIa) Hydrolyzate (Ia) and hydrolyzate (IIa) were each dissolved in 0.02 mol/L hydrochloric acid to prepare 50 mL of solution. This solution was filtered through a 0.45 μm membrane filter and used as a sample for quantitative analysis. Quantitative analysis was performed using an amino acid analyzer (high-performance liquid chromatograph “Chromaster amino acid (NIN method) analysis system” manufactured by Hitachi High-Technologies Corporation). A hydrochloric acid solution of L-cysteic acid was used as a standard sample for quantitative determination.

Table 1 below shows the amount of cysteic acid (Ia) in the hydrolyzate (Ia) and the amount of cysteic acid (IIa) in the hydrolyzate (IIa) (the unit in Table 1 is % by mass, and the numerical values are the number of times of determination. It is the average value of 50 times.). The cysteinic acid amount (IIa) based on the comparative hair a placed under the hair damage imparting environment a by ultraviolet rays is higher than the cysteinic acid amount (Ia), and the comparative hair a is damaged more than the reference hair a. I was able to evaluate it.

(Example B)
Quantitation of the amount of cysteic acid (Ib) in the hydrolyzate (Ib) obtained by performing hydrolysis b of the reference hair b after placing it under the damage imparting environment b, and after placing it under the damage imparting environment b The amount of cysteic acid (IIb) in the hydrolyzate (IIb) obtained by performing hydrolysis b of comparative hair b was quantified (the amount of cysteic acid (Ib) coincides with the amount of cysteic acid (IIa). is a thing.). Comparative hair b was contacted with composition b prior to exposure to damaging environment b. Details are as follows.

Reference hair b and comparison hair b
Reference hair b and comparative hair b were prepared in the same manner as the reference hair a and comparative hair a.

Contact with Composition b A composition containing 0.1% by weight of ascorbyl tetra-2-hexyldecanoate and 99.9% by weight of isostearic acid was designated Composition b. For contact with composition b, 0.1 g of composition b was applied to 1 g of comparative hair b prior to exposure to damaging environment b and each day during exposure to damaging environment b. Then, it was performed by blowing hot air from a hair dryer. Before the daily application, the comparative hair b was immersed in a 1% by mass sodium lauryl sulfate aqueous solution for 30 minutes and then washed with water.

Damage imparting environment b
The damage-imparting environment b was the same as the damage-imparting environment a, and the reference hair b and the comparative hair b were placed under the damage-imparting environment b.

hydrolysis b
Hydrolysis b was carried out in the same manner as hydrolysis a above.

Recovery of hydrolyzate (Ib) and hydrolyzate (IIb) Recovery of hydrolyzate (Ib) and hydrolyzate (IIb) in the same manner as in the recovery of hydrolyzate (Ia) and hydrolyzate (IIa) did.

Determination of Cysteic Acid Amount (Ib) and Cysteic Acid Amount (IIb) In the same manner as the determination of the cysteic acid amount (Ia) and the cysteic acid amount (IIa), the cysteic acid amount (Ib) and the cysteic acid amount (IIb) were quantified. gone.

Table 2 below shows the amount of cysteic acid (Ib) in the hydrolyzate (Ib) and the amount of cysteic acid (IIb) in the hydrolyzate (IIb) (the unit in Table 2 is % by mass, and the numerical values are the number of times of determination. It is the average value of 50 times.). The amount of cysteic acid (IIb) based on comparative hair b that was brought into contact with composition b before being placed under damage imparting environment b was lower than the amount of cysteic acid (Ib), and damage inhibition by composition b was evaluated. did it.

(Reference example A)
Circumferential cut surfaces of the hair (reference hair a and comparative hair a after being placed under the damage imparting environment a) were measured for distribution of cysteic acid using an infrared microscope. The details are as follows. It was prepared by cutting hair frozen in pure water to a thickness of 10 μm with a cryomicrotome. The cut surface of the hair was placed on a barium fluoride plate on the stage of a BL43IR infrared microscope (“Hyperion 2000” manufactured by Bruker) at SPring-8, a large synchrotron radiation facility, and transmission measurement was performed. The measurement was performed in 5 μm unit steps using a mapping stage, and an infrared absorption spectrum was obtained at a wave number resolution of 4 cm ⁻¹ in the range of 4000-600 cm ⁻¹ for each measurement point. At this time, the aperture size was set to 6 μm×6 μm, and the number of accumulation times was set to 64.

FIG. 1 is an infrared spectrum example of a reference hair a (-) and a comparison hair a (...). Since the S—O stretching vibration peak derived from cysteinic acid is around 1040 cm ⁻¹ , the area value I _1065-1030 of the absorption peak at 1065-1030 cm ⁻¹ was calculated, and the effect of hair thickness was removed. The intensity area value of SO was corrected based on the intensity area value I _1600-1470 of the amide II (N—H) bond absorption peak at 1600-1470 cm ⁻¹ (calculation formula for correction: I _1065-1030 / I _{1600 -1470} ). FIG. 2 shows the average values of I _1065-1030 /I _1600-1470 at all measurement points of reference hair a and comparative hair a (the average value is the average of 4 samples). According to this average value of I _1065-1030 /I _1600-1470 , compared to the reference hair a, the UV-treated comparative hair a is higher, so it is considered that cysteic acid is generated inside the hair.

Furthermore, from the results shown in FIG. 3, it can be said that cysteic acid is generated inside the hair. FIG. 3 is a graph showing the average values of I _1065-1030 /I _1600-1470 at each measurement point in the radial direction of the cut surface of the reference hair a and the comparative hair a. I _1065-1030 /I _1600-1470 are higher in comparison hair a after UV irradiation than in reference hair a at any measurement point, so cysteic acid was generated from the hair surface to the inside of the hair. It can be understood.

FIG. 4 shows measurement results of cysteic acid relative intensity mapping of reference hair a and comparative hair a using an infrared microscope. This result also confirms that cysteic acid was generated throughout the inside of comparative hair a after ultraviolet irradiation. In other words, damage to hair caused by ultraviolet rays reaches not only the surface but also the inside.

(Reference example B)
The distribution state of cysteic acid was measured in the same manner as in Reference Example A above for the reference hair b after being placed under the damaging environment b and the comparative hair b after being placed under the damaging environment b.

FIG. 5 shows measurement results of cysteic acid relative intensity mapping of reference hair b and comparative hair b, as in Reference Example A. FIG. Although both the reference hair b and the comparative hair b were irradiated with ultraviolet rays, the comparative hair b, which was contacted with the composition b, was less damaged than the reference hair b.

It was confirmed by SPring-8 that ascorbyl tetra-2-hexyldecanoate in composition b penetrates into the interior of the hair. correlates with

Claims (3)

The amount of cysteic acid (I) in the hydrolyzate (I) obtained by hydrolyzing the reference hair,
Cysteic acid amount (II) in hydrolyzate (II) obtained by hydrolyzing comparative hair,
A hair damage evaluation method that compares
The reference hair and/or the comparative hair are placed under an environment of light damage,
A method for evaluating hair damage, wherein said hydrolyzate (I) and said hydrolyzate (II) are obtained by hydrolysis from chopped hair. 2. A method for assessing hair damage according to claim 1, wherein one or more compounds or compositions are brought into contact with the reference hair and/or the comparison hair prior to exposure to the damaging environment. a first step of providing reference hair that has been contacted with one or more compounds or compositions and comparative hair that has not been contacted with the compound or composition ;
a second step of exposing the reference hair and the comparative hair to a light-damaging environment;
After chopping the reference hair obtained in the second step, the hydrolyzate (I) is obtained by hydrolysis, and after chopping the comparative hair obtained in the second step, the hydrolyzate is hydrolyzed. a third step of obtaining the product (II);
a fourth step of comparing the amount of cysteic acid (I) in the hydrolyzate (I) with the amount of cysteic acid (II) in the hydrolyzate (II);
A method for evaluating a compound or composition, comprising:

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