CN118178261A - Application of hyaluronic acid in the preparation of preparations for promoting the production of keratin CK15 - Google Patents

Abstract

The invention discloses the application of hyaluronic acid in preparing a preparation for promoting the generation of keratin CK15, and belongs to the technical field of skin science; the application of hyaluronic acid provided by the invention in preparing a preparation for promoting the generation of keratin CK15 is confirmed by experiments of the invention, and hyaluronic acid within a specific polydispersity coefficient and viscosity-average molecular weight range can effectively promote the generation of keratin CK15; when the hyaluronic acid is applied to a composition, the hyaluronic acid can better promote the generation of keratin CK15 on the basis of satisfying applicability within a certain pH value range of the composition, thereby achieving the promoting effect of the composition on the generation of keratin CK15.

Description

Application of hyaluronic acid in the preparation of preparations for promoting the production of keratin CK15

Technical Field

The invention belongs to the field of skin science, and in particular relates to the application of hyaluronic acid in the preparation of a preparation for promoting the generation of keratin CK15.

Background technique

Cytokeratin 15 is a class of structural proteins found in animal cells that form an important component of the cytoskeleton. These proteins contribute to the maintenance of cell morphology, mechanical strength, and intracellular signaling. CK15 is a member of the cytokeratin family and is primarily expressed in the skin, hair follicles, and other structures. In the skin, this protein is usually localized in basal cells, which are an important source of skin regeneration and maintenance of skin integrity. The expression of CK15 in stem cells and basal cells is essential for maintaining the regenerative capacity of the skin. Basal cells not only provide structural support for the skin, but also differentiate into other types of skin cells, promoting skin renewal and repair. The presence of CK15 in these cells helps maintain their stem cell state and is involved in regulating the process of cell differentiation.

In addition, CK15 is also related to the function of hair follicles. Hair follicles are structures that produce hair, and the basal cells in them also express CK15. These basal cells play an important role in the growth cycle of hair follicles, helping to maintain hair growth and regeneration. That is, as part of the cytokeratin family, CK15 plays a key role in skin regeneration, cell structure maintenance, and hair growth cycle.

Hyaluronic acid is a macromolecular polysaccharide, also known as hyaluronic acid, which was first extracted and separated from the vitreous of bovine eyes by Meyer, a professor of ophthalmology at Columbia University in the United States, in 1934. Hyaluronic acid is a transparent, viscous, colloid substance. This magical substance has a special water-retaining effect and is the best moisturizing substance found in nature. Hyaluronic acid is a natural biological substance widely found in tissues such as vitreous body, skin, umbilical cord, and synovial fluid. Early hyaluronic acid raw materials were mainly separated and extracted from cockscombs, so they were limited by cost and raw materials and were not further promoted. Today's hyaluronic acid is mainly produced by microbial fermentation, which is not limited by animal raw materials, has low cost, is easy to mass produce, and has high product purity. Most of the "hyaluronic acid" on the market exists in the form of sodium salt of hyaluronic acid, which is used as a moisturizer. In recent years, zinc salt of hyaluronic acid has begun to be used in the field of skin care, and its efficacy focuses on anti-inflammatory and repair. Hyaluronic acid itself (non-salt) has a low pH value (2.5-4.5) and is highly acidic, while the pH value of human skin is generally 4.5-6.5. Therefore, its application in general neutral skin care products is limited. Even if it is added to the formula, it loses its efficacy under acidic conditions due to the limitation of the formula pH value.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a use of hyaluronic acid in the preparation of a preparation for promoting the production of keratin CK15.

To achieve the above object, in a first aspect of the present invention, the present invention provides the use of hyaluronic acid in the preparation of a preparation for promoting the production of keratin CK15.

The present invention has found that hyaluronic acid can effectively promote the production of keratin CK15, and therefore can be used to prepare a preparation for promoting the production of keratin CK15.

As a preferred embodiment of the application of the present invention, the polydispersity coefficient of the hyaluronic acid is 4.0-6.5, and the viscosity-average molecular weight is 3-20 kDa.

The polydispersity coefficient (PD) characterizes the width of the molecular weight distribution curve, which is calculated as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), that is, polydispersity coefficient = weight average molecular weight / number average molecular weight. The viscosity average molecular weight (Mv) is the average molecular weight measured by the solution viscosity method; the weight average molecular weight, number average molecular weight and viscosity average molecular weight can be measured by referring to the method in patent CN108992369B.

Exemplarily, the polydispersity index of the hyaluronic acid may be any point value or any two point range values between 4.0 and 6.5, such as 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.6 .5, etc.; the viscosity-average molecular weight of the hyaluronic acid can be any point value or any two point range values between 3-20kDa, for example, it can be 3kDa, 4kDa, 5kDa, 6kDa, 7kDa, 8kDa, 9kDa, 10kDa, 11kDa, 12kDa, 13kDa, 14kDa, 15kDa, 16kDa, 17kDa, 18kDa, 19kDa, 20kDa, etc.

As a preferred embodiment of the application of the present invention, the polydispersity coefficient of the hyaluronic acid is 4.8-5.9, and the viscosity-average molecular weight is 8-13 kDa.

The present invention has found that the polydispersity coefficient and viscosity-average molecular weight of hyaluronic acid will affect the effect of keratin CK15 production. When the polydispersity coefficient of hyaluronic acid is further selected to be 4.0-6.5 and the viscosity-average molecular weight is 3-20kDa, especially when the polydispersity coefficient is 4.8-5.9 and the viscosity-average molecular weight is 8-13kDa, the obtained hyaluronic acid has a better effect in promoting the production of keratin CK15.

Preferably, the weight average molecular weight of the hyaluronic acid is 8-60 kDa, and the number average molecular weight is 2-9 kDa.

More preferably, the weight average molecular weight of the hyaluronic acid is 18-22 kDa, and the number average molecular weight is 3-5 kDa.

The weight average molecular weight (Mw) is obtained by multiplying the weight fraction of each molecule by its corresponding molecular weight, that is, the molecular weight averaged by weight; the number average molecular weight (Mn) is the total weight of all polymer molecules in the sample divided by the total number of molecules.

The ratio of weight average molecular weight to number average molecular weight is the polydispersity coefficient. The present invention has found that when the weight average molecular weight and number average molecular weight of hyaluronic acid are within the above range, especially within a more preferred range, the obtained hyaluronic acid has a better effect in promoting keratin CK15.

Preferably, the pH value of the 0.1% aqueous solution of hyaluronic acid is 2.5-4.5.

In a second aspect of the present invention, the present invention provides a composition for promoting the production of keratin CK15, wherein the composition comprises hyaluronic acid.

As a preferred embodiment of the composition of the present invention, the polydispersity coefficient of the hyaluronic acid is 4.0-6.5, and the viscosity average molecular weight is 3-20 kDa.

As a preferred embodiment of the composition of the present invention, the polydispersity coefficient of the hyaluronic acid is 4.8-5.9, and the viscosity average molecular weight is 8-13 kDa.

Preferably, the weight average molecular weight of the hyaluronic acid is 8-60 kDa, and the number average molecular weight is 2-9 kDa.

More preferably, the weight average molecular weight of the hyaluronic acid is 18-22 kDa, and the number average molecular weight is 3-5 kDa.

The present invention has found that when the polydispersity coefficient, viscosity-average molecular weight and other parameters of hyaluronic acid are further selected within the above ranges and used as a component of the composition, the resulting composition can better promote the production of keratin CK15.

As a preferred embodiment of the composition of the present invention, the mass percentage of hyaluronic acid is 0.05-0.2% based on the composition.

The present invention has found that adding 0.05-0.2% hyaluronic acid to the composition can better promote the production of keratin CK15.

As a preferred embodiment of the composition of the present invention, the pH value of the composition is 4.0-5.5.

Exemplarily, the pH value of the composition can be any point value or any two point range value between 4.0-5.5, such as 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, etc.

The present invention has found that when the pH value of the composition is controlled to be 4.0-5.5, the unique efficacy characteristics of hyaluronic acid under acidic conditions can be exerted, and this pH value range is also non-irritating to human body application; when the pH value is too low, there will be a certain degree of irritation, and when the pH value is too high, such as reaching about 6.0, although it presents a weakly acidic environment and is less irritating, the efficacy of the obtained composition in promoting the production of keratin CK15 shows a downward trend; that is, the pH value range of the composition selected by the present invention can satisfy the applicability of skin care products while exerting the optimal efficacy.

As a preferred embodiment of the composition of the present invention, the composition further comprises a skin care product base.

Preferably, the skin care product matrix includes at least one of water, an emulsifier, a surfactant and a preservative.

Preferably, by selecting different skin care product bases, different types of compositions can be prepared, for example, the composition can be a face cream, an essence water, an essence milk, a face mask, a gel, and the like.

The present invention has found that selecting different forms of skin care product matrices and compounding them with the hyaluronic acid of the present invention to form corresponding compositions can effectively promote the production of keratin CK15, so that the obtained compositions can specifically achieve the effects of exfoliation, hair care, etc.

Compared with the prior art, the present invention has the following beneficial effects:

The use of the hyaluronic acid provided by the present invention in the preparation of a preparation for promoting the production of keratin CK15 is confirmed by experiments of the present invention. The hyaluronic acid within a specific polydispersity coefficient and viscosity-average molecular weight range can effectively promote the production of keratin CK15. When the hyaluronic acid is applied to a composition, the hyaluronic acid can better promote the production of keratin CK15 on the basis of satisfying the applicability within a certain pH value range of the composition, thereby achieving the promoting effect of the composition on the production of keratin CK15.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the verification results in Effect Example 2.

Detailed ways

In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

The hyaluronic acid used in the examples and comparative examples of the present invention is obtained by fermentation and purification of Streptococcus zooepidemicus (purchased from ATCC, catalog number HA-116ATCC39920);

The specific method for preparing hyaluronic acid 1 is as follows:

Culture medium

Slant medium (g/L): brain heart infusion powder (BHI) 36g/L, glucose 12g/L, yeast powder 12g/L, agar powder 24g/L, pH value of slant medium is 7.2;

Seed culture medium (g/L): glucose 40g/L, yeast powder 20g/L, magnesium sulfate heptahydrate 2.0g/L, manganese sulfate tetrahydrate 0.1g/L, potassium dihydrogen phosphate 2.0g/L, calcium carbonate 20g/L, the pH value of the seed culture medium is 7.0;

Fermentation medium (g/L): yeast powder 20g/L, disodium hydrogen phosphate 6.2g/L, potassium sulfate 1.3g/L, glucose 140g/L, magnesium sulfate heptahydrate 2.0g/L, the pH value of the fermentation medium is 7.0.

Cultivation methods

Slant culture: The inoculated slant was placed in a constant temperature incubator at 37±0.2℃ for 16±0.5h and used for shake flask inoculation;

Seed culture: inoculate the cultured slant seeds into a 500mL Erlenmeyer flask containing 50mL of seed culture medium, shake at 200r/min, temperature at 37±0.2℃, and culture for 15h;

Fermentation culture: the seed culture medium was inoculated into a fully automatic fermenter KFT-7L (BiostatB2nd generation 1000009844, Sartorius, Germany) at an inoculation rate of 10%, 3.5 L of fermentation medium was placed in the tank, the stirring speed was 200±10 r/min, the ventilation volume was 1.0 vvm, the temperature was 37±0.2°C, the pH was detected online by a pH electrode, and 5 mol/L NaOH solution was added by an automatic feeding pump to adjust the pH to maintain the pH change within 7.0±0.1; the dissolved oxygen concentration was detected online by a dissolved oxygen electrode, and samples were taken every 2 hours for detection and analysis.

Extraction and purification

Take an appropriate amount of fermentation liquid, place it in a stainless steel tank (the discharge port is connected to a plate and frame filter), add water, adjust to a concentration of about 0.5%, stir the mixed liquid, the stirring speed is 200±10r/min, the temperature is 60℃, mix for about 30 minutes, after mixing evenly, add 6mol/L HCl to adjust the pH to 1.5, continue stirring at this temperature for 8h, then start to discharge the liquid, the discharge time lasts for 6h, and the tank is kept in a stirring state during the discharge. After discharging and filtering until the transmittance of the filtrate reaches 99.9% (550nm), a mixed filtrate 1 is obtained, placed in a stainless tank, kept stirring, and the stirring speed is 200±10r/min to obtain a mixed filtrate 2. Take the mixed filtrate 2, add 70% ethanol to precipitate, keep stirring, and the stirring speed is 50±5r/min to obtain a mixed liquid 3. Take the mixed liquid 3, centrifuge it for 1 hour at a speed of 4000r/min, discard the supernatant, take the lower layer of sediment, dry it, turn the plate every 2 hours, take a dry sample to determine the drying loss, dry it to constant weight, crush it, pass it through an 80-mesh sieve, and obtain the product.

The parameters of hyaluronic acid 1 are: Mv=3.0 kDa, Mw=8.2 kDa, Mn=2.04 kDa, PD=4.02.

The only difference between the preparation method of hyaluronic acid 2 and hyaluronic acid 1 is that during the extraction and purification, 6 mol/L HCl is added to adjust the pH to 1.5, and stirring is continued at this temperature for 6 hours, and then the feed liquid is started to be discharged, and the discharge time lasts for 8 hours; the parameters of the prepared hyaluronic acid 2 are: Mv=8.1kDa, Mw=18.6kDa, Mn=3.2kDa, PD=5.81.

The only difference between the preparation method of hyaluronic acid 3 and hyaluronic acid 1 is that during the extraction and purification, 6 mol/L HCl is added to adjust the pH to 1.8, and stirring is continued at this temperature for 6 hours, and then the feed liquid is discharged, and the discharge time lasts for 6.5 hours; the parameters of the prepared hyaluronic acid 3 are: Mv=12.2kDa, Mw=21.6kDa, Mn=4.5kDa, PD=4.8.

The only difference between the preparation method of hyaluronic acid 4 and hyaluronic acid 1 is that during the extraction and purification, 6 mol/L HCl is added to adjust the pH to 2.0, and stirring is continued at this temperature for 5 hours, and then the feed liquid is discharged, and the discharge time lasts for 7 hours; the parameters of the prepared hyaluronic acid 4 are: Mv=19.9 kDa, Mw=57.9 kDa, Mn=8.9 kDa, PD=6.5.

The only difference between the preparation method of hyaluronic acid 5 and hyaluronic acid 1 is that during the extraction and purification, 6 mol/L HCl is added to adjust the pH to 2.2, and stirring is continued at this temperature for 4 hours, and then the feed liquid is started to be discharged, and the discharge time lasts for 6 hours; the parameters of the prepared hyaluronic acid 5 are: Mv=50.2kDa, Mw=117.6kDa, Mn=24.5kDa, PD=4.8.

The only difference between the preparation method of hyaluronic acid 6 and hyaluronic acid 1 is that during the extraction and purification, 6 mol/L HCl is used to adjust the pH to 1.5, and then stirring is continued at this temperature for 9 hours, and then the feed liquid is discharged, and the discharge time lasts for 6.5 hours; the parameters of the prepared hyaluronic acid 6 are: Mv=2.1 kDa, Mw=6.7 kDa, Mn=1.4 kDa, PD=4.8.

The only difference between the preparation method of hyaluronic acid 7 and hyaluronic acid 1 is that during the extraction and purification, 6 mol/L HCl is added to adjust the pH to 1.8, and stirring is continued at this temperature for 6.5 hours, and then the feed liquid is discharged, and the discharge time lasts for 3 hours; the parameters of the prepared hyaluronic acid 7 are: Mv=12.5kDa, Mw=17.4kDa, Mn=6.2kDa, PD=2.8.

The only difference between the preparation method of hyaluronic acid 8 and hyaluronic acid 1 is that during the extraction and purification, 6 mol/L HCl is used to adjust the pH to 1.8, and then stirring is continued at this temperature for 5 hours, and then the feed liquid is discharged, and the discharge time lasts for 10 hours; the parameters of the prepared hyaluronic acid 8 are: Mv=12.8kDa, Mw=30.5kDa, Mn=3.5kDa, PD=8.7.

Examples and Comparative Examples

The embodiments of the present invention and the comparative examples provide a facial cream, the components (mass percentage) of the facial cream are shown in Table 1;

Table 1

The preparation method of the facial cream provided in Example 1 is:

(1) Preparation of phase C: Weigh hyaluronic acid, add water and stir until completely dissolved, then adjust the pH value to between 4.0 and 5.5 with an appropriate amount of 1% by mass sodium bicarbonate aqueous solution to obtain phase C;

(2) Preparation of phase A: Weigh the components in phase A, mix them, heat them to 85° C., and stir them evenly to obtain phase A;

(3) Preparation of phase B: Weigh the components of phase B, mix them, heat them to 85° C., and stir them evenly to obtain phase B;

(4) Add phase A in step (2) to phase B in step (3), stir evenly, cool to 45°C, add phase C in step (1), and stir to mix evenly;

(5) adjusting the pH value to 4.8 with an appropriate amount of 1% by mass sodium bicarbonate aqueous solution, aging, and obtaining a facial cream.

The preparation methods of the creams (placebo creams) provided in Examples 2-6, Comparative Examples 1-5 and Blank Examples are consistent with that in Example 1, except that no relevant components are added.

Example 7

The embodiment of the present invention provides a facial cream, the only difference between the facial cream and embodiment 1 is that in step (5), an appropriate amount of 1% by mass sodium bicarbonate aqueous solution is used to adjust the pH value to 5.4.

Example 8

The embodiment of the present invention provides a facial cream, the only difference between the facial cream and embodiment 1 is that in step (5), an appropriate amount of 1% by mass sodium bicarbonate aqueous solution is used to adjust the pH value to 4.2.

Comparative Example 6

The comparative example of the present invention provides a facial cream, the only difference between the facial cream and Example 1 is that in step (5), an appropriate amount of 1% by mass sodium bicarbonate aqueous solution is used to adjust the pH value to 6.1.

Effect Example 1

The effect example of the present invention verifies the safety of hyaluronic acid 3 aqueous solutions with different pH values or hyaluronic acid 3 aqueous solutions with different concentrations, comprising the following steps:

1. Preparation of hyaluronic acid 3 aqueous solution

(1) preparing a 1% by mass sodium bicarbonate aqueous solution for standby use;

(2) Weigh a certain amount of hyaluronic acid 3 (the mass here is determined according to the mass percentage to be prepared, for example, if the mass percentage is 0.2%, weigh 0.2 g of hyaluronic acid) and add it to 90 g of water and stir to completely dissolve it. Then adjust the pH value to a fixed value with the 1% sodium bicarbonate aqueous solution in step (1), add water to make the volume to 100 g, and test the final pH value.

2. Security Testing

The parameters of hyaluronic acid 3 aqueous solution with different concentrations and pH values are shown in Table 3. The specific test process is as follows: hyaluronic acid 3 aqueous solution with different concentrations and different pH values is used for safety test, and a placebo is set at the same time. A total of 31 subjects are included, including 5 males and 26 females, aged 23-45 years old. A suitable patch tester with an area of no more than 50 mm ² and a depth of about 1 mm is selected. By closed patch test method, about 0.020-0.025 mL of the test substance is added to the patch tester, and the patch tester is applied to the back of the subject. The test substance is removed after 24 hours, and the skin reaction is observed 0.5 hours after removal. The results are recorded according to the skin reaction grading standard (as shown in Table 2) in the Cosmetic Safety Technical Specification (2015 Edition). The obtained results are shown in Table 3;

Table 2

table 3

It can be seen from Table 3 that when the pH value of the hyaluronic acid aqueous solution is between 4.0 and 6.4 and the mass percentage of the hyaluronic acid aqueous solution is below 0.3%, the patch test results show that the results are safe and non-irritating.

Effect Example 2

The effect example of the present invention verifies the promoting effect of the cream (placebo cream) prepared by the embodiment, comparative example and blank example on keratin CK15, specifically comprising the following steps:

(1) Take appropriate amounts of the creams of Examples 1-8, Comparative Examples 1-6 and Blank Example (placebo cream) and apply them evenly on the prepared human ex vivo skin surface on T0, T2, T5 and T6 until they are completely absorbed (the ratio of the amount of the cream applied to the applied area in the Examples and Comparative Examples is consistent, 0.020-0.025 g/cm ² , the human ex vivo skin is the abdominal ex vivo skin of a 56-year-old white female, and each group has 3 skin explants); set up another group without any treatment as a blank group;

(2) The measurement site was CK15 skin stem cell marker, anti-CK15 monoclonal antibody (Santa Cruz, ref.sc-70912) was diluted to 1:500 with 0.05% PBS-BSA 0.3% Tween-20 solution, and CK15 antibody was labeled with fluorescein AF594 (Lifetechnologies, ref.A11005, red staining). The tissue was immunostained at room temperature for T7 days, and the staining was observed and evaluated using a Leica DMLB microscope. Subsequently, the image analysis software CellSens (Olympus) was used for semi-quantitative analysis to calculate the percentage of the surface of the basal layer that was positive for CK15 immunostaining. The results are shown in Table 4.

In the result analysis, the data are expressed as mean values, and the statistical analysis results are reported above the error bars as follows: the statistical analysis within the group (sample group vs. blank group) is indicated by a black asterisk (*p<0.05; **p<0.01; ***p<0.001), and the statistical analysis between the groups (sample group vs. placebo cream group) is indicated by a “#” (#p<0.05; ##p<0.01; ###p<0.001);

Table 4

As can be seen from Table 4, when the technical solution of the present invention is adopted, the obtained cream can effectively promote the production of keratin CK15, wherein the percentage of positive surface of CK15 immunostaining is above 28.5%, which is much higher than the positive surface percentage in the blank group and the placebo cream group;

It can be seen from Examples 1-3 and Comparative Example 5 that the amount of hyaluronic acid added will affect the effect of CK15 generation, and increasing the amount of hyaluronic acid added within a safe range can achieve a more excellent effect of promoting CK15 generation; it can be seen from Example 1, Examples 7-8 and Comparative Example 6 that the pH value of the finally prepared cream will also affect the product's promotion of CK15 generation. When the pH value of the cream is within the range of 4.0-5.5 given in the present invention, it can promote the generation of CK15 well. When the pH value of the cream is greater than 5.5, that is, it is not within the range of the present invention, although there is no stimulation, the ability to promote CK15 generation decreases;

It can be seen from Example 1, Examples 4-6 and Comparative Examples 1-4 that the polydispersity coefficient and viscosity-average molecular weight of hyaluronic acid will also affect the ability of the cream to promote CK15 production. When the polydispersity coefficient or viscosity-average molecular weight of the hyaluronic acid provided in Comparative Examples 1-4 is not within the scope of the present invention, the resulting product has a weak ability to promote CK15 production; when the polydispersity coefficient of hyaluronic acid is further selected to be 4.8-5.9 and the viscosity-average molecular weight is 8-13 kDa, the resulting product has excellent ability to promote CK15 production, and the percentage of the surface positive for CK15 immunostaining is above 40.6% on T7 days;

At the same time, Figure 1 provides the immunostaining results on the 7th day during the verification process, in which the more obvious and clear the green fluorescence is, the more keratin CK15 is produced. It can be seen from Figure 1 that the product provided by the technical solution of the present invention can significantly promote the production of keratin CK15 compared with the placebo cream group and the blank group.

Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims (9)

1. Use of hyaluronic acid for the preparation of a formulation for promoting the production of keratin CK 15.

2. The use according to claim 1, wherein the hyaluronic acid has a polydispersity of 4.0-6.5 and a viscosity average molecular weight of 3-20kDa.

3. The use according to claim 2, wherein the hyaluronic acid has a polydispersity of 4.8-5.9 and a viscosity average molecular weight of 8-13kDa.

4. A composition for promoting the production of keratin CK15, comprising hyaluronic acid.

5. The composition of claim 4, wherein the hyaluronic acid has a polydispersity of 4.0-6.5 and a viscosity average molecular weight of 3-20kDa.

6. The composition of claim 5, wherein the hyaluronic acid has a polydispersity of 4.8-5.9 and a viscosity average molecular weight of 8-13kDa.

7. The composition according to claim 4, wherein the mass percentage of hyaluronic acid in the composition is 0.05-0.2%.

8. The composition of claim 4, wherein the pH of the composition is 4.0-5.5.

9. The composition of claim 4, wherein the composition further comprises a skin care product base.