Solid form of ascorbic acid carbon chain dibasic acid ester and use thereof

Abstract

Disclosed in the present invention are a solid form of an ascorbic acid carbon chain dibasic acid ester and the use thereof. Specifically, the X-ray powder diffraction pattern of the solid form of an ascorbic acid carbon chain dibasic acid ester has characteristic peaks represented by the following 2θ angles: 7.2±0.2°, 14.1±0.2°, 18.5±0.2°, 18.7±0.2°, 19.8±0.2°, 22.4±0.2°, 23.9±0.2°, and 25.4±0.2°.

Description

A solid form of ascorbic acid carbon chain dibasic ester and its application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 63 / 626,547, filed with the U.S. Patent Office on January 30, 2024, entitled “A solid form of ascorbic acid carbon chain dibasic ester and its application,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a solid form of an ascorbic acid carbon chain dibasic ester and its application. The solid form of the ascorbic acid carbon chain dibasic ester has an XRPD pattern as shown in FIG1 . Background Art

[0004] In the prior art, fatty acid ester derivatives of ascorbic acid are primarily used as additives in the food industry. These fatty acid esters are virtually insoluble in water or in bases such as polyols, and their powder form is unstable. These factors hinder their application in other industries, such as skincare products.

[0005] In order to overcome the above technical barriers, the development of innovative ascorbic acid ester derivatives that can be used in the skin care products industry is a topic that urgently needs research breakthroughs in this technical field. Summary of the Invention

[0006] The ascorbic acid carbon chain dibasic acid esters and ascorbic acid alkyl dibasic acid esters described in the following invention summary and examples are synonyms with equivalent meanings and represent the same chemical structure.

[0007] The appearance of the solid forms described in the following summary of the invention and examples includes but is not limited to bulk, powder, crystals or mixtures thereof.

[0008] In light of the aforementioned invention background and to meet industry needs, the present invention aims to provide a solid form of a carbon-chain dibasic ester of ascorbic acid and its use, thereby addressing at least the current difficulties in obtaining a thermally stable solid form of a carbon-chain dibasic ester of ascorbic acid, achieving the technical benefits of stabilizing the solid form of the carbon-chain dibasic ester of ascorbic acid, and achieving the skin care benefits of the solid form of the carbon-chain dibasic ester of ascorbic acid by promoting collagen production in skin fibroblasts or keratinocytes through its use in protecting skin from UV damage.

[0009] The purpose of the present invention and the solution to the technical problem are achieved by adopting the following technical solutions.

[0010] A first aspect of the present invention is to provide a solid form of an ascorbic acid carbon chain dibasic ester. The X-ray powder diffraction pattern of the solid form of the ascorbic acid carbon chain dibasic ester (as shown in FIG1 ) has the following characteristic peaks expressed in 2θ angles: 7.2±0.2°, 14.1±0.2°, 18.5±0.2°, 18.7±0.2°, 19.8±0.2°, 22.4±0.2°, 23.9±0.2°, and 25.4±0.2°.

[0011] Specifically, the solid form of the ascorbic acid carbon chain dibasic ester has a Fourier transform infrared (FTIR) spectrum of the solid form of the ascorbic acid carbon chain dibasic ester including the following wave numbers (cm -1 ) characteristic peaks: 3416±2, 3172±2, 2928±2, 2857±2, 1749±2, 1737±2, 1681±2, 1347±2, 1305±2, 1146±2 and 761±2cm -1 .

[0012] Specifically, the solid form of the ascorbic acid carbon chain dibasic ester has a single characteristic peak at 150-160° C. in the differential scanning calorimetry (DSC) spectrum.

[0013] The second aspect of the present invention is to provide a composition for skin care, which comprises 0.0001 to 20 wt.% of the solid form of the ascorbic acid carbon chain dibasic ester as described above and 80 to 99.9999 wt.% of a base, based on the total weight of the composition, and the water activity value of the base is less than or equal to 0.7.

[0014] Specifically, the base is a water-in-oil (W / O) formulation, a water-in-silicone (W / Si) formulation, an anhydrous gel or a gel.

[0015] Specifically, the composition for skin care has the technical effect of stabilizing the solid form of the ascorbic acid carbon chain dibasic ester.

[0016] A third aspect of the present invention is to provide a method for skin care, comprising applying the solid form of the ascorbic acid carbon-chain dibasic ester formulation described above to the skin surface of an individual. Specifically, the solid form of the ascorbic acid carbon-chain dibasic ester is added in an amount of 0.0001 to 20 wt.%, based on the total weight of the formulation. More specifically, the solid form of the ascorbic acid carbon-chain dibasic ester is used to protect skin fibroblasts or keratinocytes from ultraviolet damage and to promote collagen production in skin fibroblasts or keratinocytes.

[0017] The fourth aspect of the present invention is to provide a solid formulation of ascorbic acid carbon chain dibasic ester, which can be used to protect skin fibroblasts or keratinocytes from damage by ultraviolet rays.

[0018] Specifically, the formulation is in the form of one of the following groups: cream, lotion, gel, powder, and paste. The formulation, based on the solid form of the ascorbic acid carbon chain dibasic ester, has the purpose of promoting the production of collagen by skin fibroblasts or keratinocytes.

[0019] In summary, the technical means and functions of the present invention include, but are not limited to: providing a thermally stable solid form of ascorbic acid carbon-chain dibasic ester; stabilizing the solid form of ascorbic acid carbon-chain dibasic ester by controlling the water activity value of the composition; and promoting the production of collagen by skin fibroblasts or keratinocytes through the solid form of ascorbic acid carbon-chain dibasic ester to achieve a skin care effect.

[0020] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above-mentioned structure and other purposes, features and advantages of the present invention more obvious and easy to understand, the following lists preferred embodiments and describes them in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is an XRPD pattern of the solid form of the ascorbic acid carbon chain dibasic ester of the present invention.

[0022] FIG2 is an FTIR spectrum of the solid form of the ascorbic acid carbon chain dibasic ester of the present invention.

[0023] FIG3 is a DSC spectrum of the solid form of the carbon chain dibasic acid ester of ascorbic acid of the present invention.

[0024] FIG4 is an XRPD pattern of the solid of Experimental Example 3 of the present invention.

[0025] FIG5 is an XRPD pattern of the solid form of the ascorbic acid carbon chain dibasic ester of the present invention stored in an oven at 45° C. for one month.

[0026] FIG6 is an XRPD pattern of the solid of Experimental Example 3 of the present invention stored in an oven at 45° C. for 1 month.

[0027] FIG. 7 is a bar graph showing the effect of ascorbic acid carbon chain dibasic esters of the present invention on the recovery of cell viability after UV irradiation.

[0028] FIG8 is a bar graph showing that ascorbic acid carbon chain dibasic esters of the present invention reduce the intracellular ROS content after UV irradiation.

[0029] FIG9 is a bar graph showing that ascorbic acid carbon chain dibasic ester of the present invention reduces the intracellular IL-6 content in cells after UV irradiation.

[0030] FIG. 10 is a bar graph showing the effect of ascorbic acid carbon chain dibasic esters of the present invention on increasing collagen production in skin fibroblasts. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects proposed in accordance with the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0032] In general, a first embodiment of the present invention provides a solid form of an ascorbic acid carbon chain dibasic ester. Specifically, the solid form of the ascorbic acid carbon chain dibasic ester comprises greater than or equal to 90 wt.% of bis-(L-ascorbic acid-6,6-)nonanedioate.

[0033] In a preferred embodiment, the solid form of the ascorbic acid carbon chain dibasic ester comprises greater than or equal to 95 wt.% of bis-(L-ascorbic acid-6,6-)nonanedioate. In a more preferred embodiment, the solid form of the ascorbic acid carbon chain dibasic ester comprises greater than or equal to 99 wt.% of bis-(L-ascorbic acid-6,6-)nonanedioate and less than or equal to 1 wt.% of ascorbic acid.

[0034] In one embodiment, the solid form of the ascorbic acid carbon chain dibasic ester comprises less than or equal to 5 wt.% of bis-(L-ascorbic acid-5,6-)nonanedioate, bis-(L-ascorbic acid-5,5-)nonanedioate, or a combination thereof.

[0035] In one embodiment, the solid form of the ascorbic acid carbon chain dibasic ester comprises less than or equal to 5 wt.% of ascorbic acid-6-nonanedioate, ascorbic acid-5-nonanedioate, or a combination thereof.

[0036] In an embodiment, the solid form of the ascorbic acid carbon chain dibasic ester comprises greater than or equal to 90 wt.% of diascorbic acid 6,6-azelazolate, and the solid form of the ascorbic acid carbon chain dibasic ester exhibits the following characteristic peaks, expressed in 2θ angles, in an X-ray powder diffraction pattern: 7.2±0.2°, 14.1±0.2°, 18.5±0.2°, 18.7±0.2°, 19.8±0.2°, 22.4±0.2°, 23.9±0.2°, and 25.4±0.2°. In a specific embodiment, the X-ray powder diffraction pattern of the solid form of the ascorbic acid carbon chain dibasic ester is shown in Figure 1.

[0037] In an embodiment, the composition of the solid form of the ascorbic acid carbon chain dibasic ester comprises greater than or equal to 90 wt.% of diascorbic acid-6,6-azelatonate, and the Fourier transform infrared spectrum of the solid form of the ascorbic acid carbon chain dibasic ester comprises characteristic peaks at the following wave numbers: 3416±2, 3172±2, 2928±2, 2857±2, 1749±2, 1737±2, 1681±2, 1347±2, 1305±2, 1146±2, and 761±2 cm-1 In a specific embodiment, the Fourier transform infrared spectrum of the solid form of the ascorbic acid carbon chain dibasic ester is shown in FIG2 .

[0038] In an embodiment, the solid form of the ascorbic acid carbon-chain dibasic ester comprises greater than or equal to 90 wt.% of diascorbic acid 6,6-azelazolate, and the solid form of the ascorbic acid carbon-chain dibasic ester exhibits a single characteristic peak at 150°C to 160°C in a differential scanning calorimetry (DSC) analysis. In a specific embodiment, the DSC analysis of the solid form of the ascorbic acid carbon-chain dibasic ester is shown in Figure 3.

[0039] In an embodiment, the solid form of ascorbic acid carbon chain dibasic ester as shown in Figure 1 is a solid form obtained by recrystallization using an ester solvent. In a specific embodiment, the ester solvent includes ethyl acetate, isopropyl acetate or a combination thereof.

[0040] A second embodiment of the present invention provides a composition for skin care, comprising, based on the total weight of the composition, 0.0001 to 20 wt.% of the solid form of the ascorbic acid carbon chain dibasic ester described in the first embodiment and 80 to 99.9999 wt.% of a base, wherein the base has a water activity value of less than or equal to 0.7. In an embodiment, the base has a water activity value of less than 0.6.

[0041] In a specific embodiment, the substrate having a water activity value less than 0.6 includes but is not limited to gelatin, fatty acids (such as MBK TM), mixtures containing polyethylene glycol and mineral oil (such as the trade name Plasticized TM ), a mixture containing silicone oil and vegetable oil (such as the trade name ), mixtures containing phospholipids (such as Anwaterus ), anhydrous gel (such as trade name PermE8 TM or W06 TM Anwaterus Topical Gel), a mixture containing an emulsified wax and fatty acid esters (such as the trade name VersaBase Cream), or a composition similar to the above.

[0042] In a preferred embodiment, the composition for skin care comprises 0.1-20 wt.% of the solid form of the ascorbic acid carbon chain dibasic ester; in a more preferred embodiment, the composition for skin care comprises 1-10 wt.% of the solid form of the ascorbic acid carbon chain dibasic ester.

[0043] In an embodiment, the base is a water-in-oil (W / O) formulation, a water-in-silicone (W / Si) formulation, an anhydrous gel, or a gel.

[0044] In a specific embodiment, the water activity value of the water-in-oil (W / O) formulation is between 0.5 and 0.65; the water activity value of the anhydrous gel or gel is between 0.4 and 0.7.

[0045] In one embodiment, the base composition comprises vegetable oil, mineral oil, polyol, silane (silicone oil) or any combination thereof.

[0046] In an embodiment, the vegetable oil comprises jojoba oil, black cumin oil, grapeseed oil, sunflower seed oil, olive oil, avocado oil, argan oil, macadamia oil, sweet almond oil, apricot kernel oil, sesame oil, bacas oil, or a combination thereof.

[0047] In an embodiment, the polyol comprises glycerol, butanediol, 1,3-propylene glycol, 1,2-propylene glycol, 1,2-pentanediol, 1,2-hexanediol, polyethylene glycol, poly(1,3-propylene glycol), cyclodextrin and its derivatives, cellulose and its derivatives, or a combination thereof.

[0048] In a specific embodiment, the silane comprises polydimethylsiloxane, cyclopentasiloxane, or a combination thereof.

[0049] In a specific embodiment, the base further comprises a pH buffer (such as sodium citrate buffer), an antioxidant (such as vitamin E or sodium bisulfite), a thiol compound (such as cysteine ​​or cystamine), a chelating agent (such as ethylenediaminetetramethylenephosphonic acid (EDTMP) or its salts), water, or a combination thereof.

[0050] A third embodiment of the present invention provides a method for skin care, comprising applying a solid formulation of the ascorbic acid carbon chain dibasic ester described in the first embodiment to the skin surface of an individual, wherein the formulation is in a form selected from one of the following groups: cream, lotion, gel, powder, and paste.

[0051] In an embodiment, the weight percentage of the solid form of ascorbic acid carbon chain dibasic ester added to the formulation is 0.0001-20 wt.%, based on the total weight of the formulation, and in a preferred embodiment, the weight percentage is 0.1-10 wt.%.

[0052] In an embodiment, the solid form of the carbon-chain dibasic ester of ascorbic acid is used to protect skin fibroblasts or keratinocytes from ultraviolet damage. A fourth embodiment of the present invention provides a formulation of a solid form of the carbon-chain dibasic ester of ascorbic acid, which is used to protect skin fibroblasts or keratinocytes from ultraviolet damage.

[0053] In an embodiment, the formulation is in a form selected from one of the following groups: cream, lotion, gel, powder, and paste.

[0054] In an embodiment, the solid form of the ascorbic acid carbon chain dibasic ester has the use of promoting skin fibroblasts or keratinocytes to produce collagen.

[0055] In a specific embodiment, the solid form of the ascorbic acid carbon chain dibasic ester has the effect of preventing and repairing cell damage caused by UV, and the effective concentration is greater than 125 ppm.

[0056] In a specific embodiment, the solid form of the ascorbic acid carbon chain dibasic ester has the effect of significantly reducing intracellular reactive oxygen species, and the effective concentration is greater than 125 ppm.

[0057] In a specific embodiment, the solid form of the ascorbic acid carbon chain dibasic ester has the effect of significantly reducing intracellular inflammatory mediators, and the effective concentration is greater than 125 ppm.

[0058] In an embodiment, the solid form of the carbon-chain dibasic ester of ascorbic acid has the use of promoting the production of collagen by skin fibroblasts or keratinocytes. In a specific embodiment, the solid form of the carbon-chain dibasic ester of ascorbic acid has the ability to increase the production of collagen by fibroblasts, and the effective concentration is greater than 1 ppm.

[0059] Experimental Example 1: Preparation of ascorbic acid carbon chain dibasic ester

[0060] Ascorbic acid (3 equivalents), azelaic acid (1 equivalent), and lipase (20 wt.% of the total weight of the reactants) were added to an aprotic reaction solvent; the temperature was raised to 60°C to 80°C under nitrogen for reaction. After the reaction was completed, the lipase was removed by filtration, the excess ascorbic acid was removed by washing with water, and the aprotic reaction solvent was removed by concentration to obtain a crude product of diascorbic acid azelaic acid ester. After column purification, the product was obtained. HPLC analysis showed that the composition of the product was greater than 90 wt.% of diascorbic acid-6,6-zelaic acid ester, and the residual ascorbic acid was 0.62 wt.%. Mass spectrum (MS-ESI): 503.20; H NMR analysis data are shown in Table 1. The molecular formula is C 21 H 28 O 14 .

[0061] Table 1

[0062] Experimental Example 2: Recrystallization Procedure - Ester Crystallization Solvent

[0063] In Experimental Example 1, the prepared ascorbic acid carbon chain dibasic ester (comprising greater than 90 wt.% diascorbic acid 6,6-azelanate) was recrystallized by heating and refluxing in an ester solvent (e.g., ethyl acetate) at a relative weight ratio of at least four times the amount. The resulting filter cake was cooled and filtered. This filter cake was then vacuum dried to obtain a solid ascorbic acid carbon chain dibasic ester. HPLC analysis showed that the composition of the solid was within the range described in Example 1. The structure of the solid was analyzed by X-ray powder scattering, and the resulting XRPD pattern is shown in Figure 1.

[0064] Experimental Example 3: Recrystallization Procedure - Non-ester Crystallization Solvent

[0065] In Experimental Example 1, the prepared ascorbic acid carbon chain dibasic ester (comprising greater than 90 wt.% diascorbic acid 6,6-azelane ester) was recrystallized by heating and refluxing in a non-ester crystallization solvent (ketone, such as acetone) at least four times its weight. The mixture was cooled and filtered to obtain a filter cake. The filter cake was then vacuum dried to obtain a solid ascorbic acid carbon chain dibasic ester. HPLC analysis showed that the composition of the solid was within the range described in Example 1. The structure of the solid was analyzed by X-ray powder scattering, and the resulting XRPD pattern is shown in Figure 4.

[0066] Experimental Example 4: Thermal stability test of solid form

[0067] The solids of the ascorbic acid carbon-chain dibasic esters obtained by recrystallization in Experimental Examples 2 and 3 were placed in a 45°C oven for one month and then removed for purity and solid-state structural analysis. HPLC analysis showed that their compositions were within the ranges described in the first embodiment. The solid forms were analyzed using an X-ray powder diffraction spectrometer, and their XRPD patterns are shown in Figures 5 and 6, respectively. Comparing Figures 1 and 5, the results show that the solid forms of the ascorbic acid carbon-chain dibasic esters obtained by recrystallization using ester solvents have high thermal stability and their structure does not change due to heat, leading to deterioration. In contrast, Figures 4 and 6 show significant differences, indicating that the thermal stability of the solid forms of the ascorbic acid carbon-chain dibasic esters obtained by recrystallization using ether or ketone solvents that do not undergo ester exchange reactions with ascorbic acid esters is actually reduced. In summary, the solid forms of the ascorbic acid carbon-chain dibasic esters obtained by recrystallization using ester solvents have the technical benefit of structural thermal stability.

[0068] Experimental Example 5: Efficacy Experiment 1 (Cell Survival Rate)

[0069] Cells were seeded into 48-well plates and cultured at 37°C, 5% CO₂ for 24 hours. The cell line used was epidermal cells (HaCaT) (AddexBio, Cat#T0020001); the cell culture medium was DMEM supplemented with 10% fetal bovine serum. The cell culture medium was replaced with a buffer solution [Sterile D-PBS (Dulbecco's phosphate buffered saline)], and the cells were irradiated with UV light. The experimental group received a buffer solution containing the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, while the positive and negative control groups received a buffer solution without the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention. Only the experimental and positive control groups were irradiated with UV light; the negative control group was cultured under normal conditions, with the cells completely covered with aluminum foil to protect them from UV light. Post-UV irradiation treatment steps were as follows: the buffer solution was replaced with cell culture medium. The experimental group was cultured in a cell culture medium containing the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, while the positive control and negative control groups were cultured in a cell culture medium without the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention. Culture was continued at 37°C and 5% CO2 for 24 hours. A cell viability assay was then performed. Cell viability in each experimental group was detected using a cell viability detection reagent (Alamar Blue), and cell viability was calculated using Equation 1. The culture conditions in the negative control group were those of normal cell viability; therefore, the cell viability of the negative control group was defined as 100% in this experiment. Comparisons between groups were performed using an unpaired Student's t-test.

[0070] Equation 1

[0071] The results of the above experimental steps, obtained after repeated experiments, are summarized in Figure 7. Under UV irradiation, the cell viability of the positive control group decreased from 100% to 55±10%. Compared to the positive control group, the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention at 125, 250, 500, and 1000 ppm restored cell viability to 88±4%, 99±5%, 114±9%, and 104±7%, respectively. These differences were statistically significant compared to the positive control group. The results demonstrate that the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention is effective in preventing and repairing UV-induced cell damage, with an effective concentration of 125 to 1000 ppm.

[0072] Experimental Example 6: Efficacy Experiment 2 (Intracellular Reactive Oxygen Species Content)

[0073] Cells were seeded into 48-well plates and cultured at 37°C, 5% CO₂ for 24 hours. The cell line used was HEKn (Gibco, Cat#C-001-5C); the cell culture medium was Epi-Life (HKGS, Gibco, Cat#S0015 & Cat#MEPI500CA) containing HKGS (Human Keratinocyte Growth Supplement). The cell culture medium was replaced. The experimental group received a cell culture medium containing the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, while the positive and negative control groups received a cell culture medium without the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention. The cells were cultured at 37°C, 5% CO₂ for 24 hours. An intracellular oxidative stress detection reagent (DCFH-DA) was added: All groups were washed with sterile Dulbecco's phosphate-buffered saline and the intracellular oxidative stress detection reagent (DCFH-DA) was added and allowed to react for 1 hour. UV irradiation: Cells were washed with sterile Dulbecco's phosphate-buffered saline (DPBS), then UV-irradiated with DPBS. Only the experimental and positive control groups underwent UV irradiation. The negative control group maintained normal culture conditions, with cells completely covered with aluminum foil to prevent UV exposure. Post-UV irradiation treatment: The buffer solution was replaced with cell culture medium. The experimental group received cell culture medium containing the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, while the positive and negative controls received cell culture medium without the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention. Culture was continued at 37°C and 5% CO₂ for 1 hour. Intracellular oxidative stress assay (ROS Generation Assay): ROS levels in each experimental group were measured using an intracellular oxidative stress assay (DCFH-DA) and calculated using Equation 2. The data from the positive control group was set as 100%. Comparisons between groups were performed using an unpaired Student's t-test.

[0074] Equation 2

[0075] The results of the above experimental steps after repeated experiments are summarized in Figure 8. The negative control group is a group without experimental material treatment and UV irradiation, and its ROS content represents the normal state. The positive control group is a group without UV irradiation and untreated experimental material, which is set to 100%. After treatment with the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, the ROS content can be significantly reduced, and it shows a dose-dependent manner. 125ppm, 250ppm, 500ppm, and 1000ppm can reduce ROS from 100% of the positive control group to 90±10%, 78±6%, 63±7%, and 52±3%, respectively. The results show that the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention has the effect of significantly reducing intracellular reactive oxygen species, and the effective concentration is 125-1000ppm.

[0076] Experimental Example 7: Efficacy Experiment 3 (Intracellular Interleukin-6 Content)

[0077] The cells were seeded into 48-well plates and cultured at 37°C and 5% CO2 for 24 hours. The cell line used was HaCaT (AddexBio, Cat#T0020001); the cell culture medium was DMEM medium with 10% fetal bovine serum. The cell culture medium was replaced with a buffer solution, and the cells were irradiated with a UV machine. Among them, the experimental group was a buffer solution containing the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl dibasic ester) of the present invention, and the positive control group and the negative control group were buffer solutions that did not contain the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl dibasic ester) of the present invention. Only the experimental group and the positive control group were UV irradiated, and the negative control group was cultured under normal conditions, and the cells were completely covered with aluminum foil to prevent them from being irradiated by UV. Post-UV irradiation treatment: the buffer solution was replaced with cell culture medium. The experimental group received cell culture medium containing the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, while the positive and negative control groups received cell culture medium without the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention. Culture was continued at 37°C, 5% CO₂ for 24 hours. Interleukin-6 (IL-6) secretion was quantified using a human IL-6 enzyme-linked immunoassay kit. Relative IL-6 content was calculated using Equation 3, with the positive control group set as 100%. Comparisons between groups were performed using an unpaired Student's t-test.

[0078] Equation 3

[0079] The results of the above experimental steps, obtained after repeated experiments, are summarized in Figure 9. The negative control group is a group without experimental material treatment and UV irradiation, and its IL-6 content represents the normal state. The positive control group is a group without UV irradiation and untreated experimental material, which is set to 100%. After treatment with the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, the IL-6 content can be significantly reduced, and it is dose-dependent. 125ppm, 250ppm, 500ppm, and 1000ppm can reduce IL-6 from 100% of the positive control group to 4±1%, 1±1%, 1±1%, and 2±1%, respectively. The results show that the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention has the effect of significantly reducing intracellular inflammatory mediators, and the effective concentration is 125-1000ppm.

[0080] Experimental Example 8: Efficacy Experiment 4 (Collagen Content)

[0081] The cells were seeded into 48-well plates and cultured at 37°C and 5% CO2 for 24 hours. The cell line used was NHDF (PromoCell, Cat#C12302); the cell culture medium was FGM2 (PromoCell, Cat#C23230). Cell treatment was performed by replacing the cell culture medium. The experimental group received a cell culture medium containing the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention, while the control group received a cell culture medium without the ascorbic acid carbon-chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention. The cells were cultured at 37°C in a 5% CO2 environment for 24 hours. Real-time quantitative polymerase chain reaction (RT-PCR) was used to measure the expression of type I collagen (Collagen I) and type IV collagen (Collagen IV) using real-time quantitative polymerase chain reaction (RT-PCR) reagents. The relative collagen expression was calculated using Equation 4, with the control group set as 100%. Comparisons between groups were performed using an unpaired Student's t-test.

[0082] Equation 4

[0083] The results of repeated experiments are summarized in Figure 10. The control group, which did not receive any treatment, had a normal collagen content, set at 100%. Treatment with the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention significantly increased collagen content. At 1 ppm, 10 ppm, 100 ppm, and 1000 ppm, the type I collagen content increased from 100% to 328±159%, 183±87%, 163±25%, and 182±30%, respectively. The type IV collagen content also increased from 100% to 170±15%, 173±36%, 171±12%, and 228±44%, respectively. The results demonstrate that the ascorbic acid carbon chain dibasic ester (ascorbic acid alkyl diacid ester) of the present invention significantly increases collagen expression by fibroblasts, with an effective concentration of 1 to 1000 ppm.

[0084] Experimental Example 9: Evaluation Test of Substrates with Different Water Activity Values

[0085] This experimental example evaluated the stability of various skin care compositions by mixing a solid form of an ascorbic acid carbon-chain dibasic ester, as shown in Figure 1, with representative substrates having varying water activity values. Specifically, the weight percentage of the solid form of the ascorbic acid carbon-chain dibasic ester, as shown in Figure 1, in the representative substrate ranged from 0.1 to 20 wt.%, while the weight percentage of the solid form of the ascorbic acid carbon-chain dibasic ester, as shown in Figure 1, in the representative substrate was 1 wt.%. The water activity values ​​of the substrates ranged from 0.05 to 0.79, as shown in Table 2.

[0086] Table 2

[0087] Among them, *Buffer (4): Sodium citrate buffer; **Buffer (pH 6): Phosphate buffer

[0088] According to Table 2, when the water activity value of the representative substrate was 0.79, the degradation rate of the ascorbic acid carbon-chain dibasic ester of the present invention was high. After one month at room temperature, the degradation rate reached 31% as determined by HPLC analysis. In contrast, when the water activity value of the representative substrate was controlled below 0.7, the stability of the ascorbic acid carbon-chain dibasic ester of the present invention in the representative substrate was improved. Even after four months at room temperature, the degradation rate was less than 20%, indicating that the content of the ascorbic acid carbon-chain dibasic ester was still greater than 80%.

[0089] Experimental Example 10: Gel

[0090] The composition of the dosage form of this experimental example is shown in Table 3. The operation steps are as follows: First, mix the ingredients in Group A. When the ascorbic acid carbon chain dibasic ester is completely dissolved, Group A is added to Group B and mixed evenly. The water activity value of the resulting gel is 0.75.

[0091] Table 3

[0092] Experimental Example 11: Oil-in-water formulation (O / W)

[0093] The formulation composition of this experimental example is shown in Table 4. The steps are as follows: First, evenly disperse xanthan gum in water. After dispersion, add Group C. Then, heat Groups A, C, and B separately. Heat to 75°C, add the oil phase to the water phase, emulsify the resulting mixture in a homogenizer, and cool to 40°C. While stirring, Group E is added sequentially. The resulting finished cream has a water activity of 0.91. The finished cream of this experimental example discolored after being left at room temperature for one month due to the cleavage of the ascorbic acid carbon chain dibasic ester.

[0094] Table 4

[0095] Experimental Example 12: Water-in-Silicone Oil Formulation (W / Si)

[0096] The composition of the dosage form of this experimental example is shown in Table 5. The operation steps are as follows: Groups A and B are mixed uniformly, and then the water phase is added to the oil phase. The resulting mixture is emulsified by a homogenizer, and its water activity value is less than 0.6.

[0097] Table 5

[0098] Experimental Example 13: Water-in-oil formulation (W / O)

[0099] The formulation composition of this experimental example is shown in Table 6. The procedure was as follows: Groups A and B were mixed separately, the aqueous phase was added to the oil phase, and the resulting mixture was emulsified using a homogenizer. The resulting finished cream had a water activity of 0.65. The color of the finished cream in this experimental example remained unchanged after being stored at room temperature for one month.

[0100] Table 6

[0101] Experimental Example 14: Anhydrous Gel

[0102] The composition of the dosage form of this experimental example is shown in Table 7. The steps are as follows: First, mix the ingredients in Group A. After the ascorbic acid carbon chain dibasic ester is completely dissolved, add Groups B and C in sequence and stir evenly to obtain an anhydrous gel with a water activity value of less than 0.6.

[0103] Table 7

[0104] The above are merely preferred embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with this profession can make slight changes or modifications to equivalent embodiments with equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present application. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A solid form of an ascorbic acid carbon chain dibasic ester, wherein: The X-ray powder diffraction pattern of the solid form of the ascorbic acid carbon chain dibasic ester has the following characteristic peaks expressed in 2θ angles: 7.2±0.2°, 14.1±0.2°, 18.5±0.2°, 18.7±0.2°, 19.8±0.2°, 22.4±0.2°, 23.9±0.2° and 25.4±0.2°.

2. The solid form of ascorbic acid carbon chain dibasic ester according to claim 1, wherein The Fourier infrared spectrum of the solid form of the ascorbic acid carbon chain dibasic ester includes the following wave numbers ( cm-1 ) characteristic peaks: 3416±2, 3172±2, 2928±2, 2857±2, 1749±2, 1737±2, 1681±2, 1347±2, 1305±2, 1146±2 and 761±2 cm-1 .

3. The solid form of ascorbic acid carbon chain dibasic ester according to claim 1, wherein The solid form of the ascorbic acid carbon chain dibasic ester has a single characteristic peak at 150° C. to 160° C. in a differential scanning calorimetry spectrum.

4. A composition for skin care, wherein: Based on the total weight of the composition, it comprises 0.0001-20 wt.% of the solid form of the ascorbic acid carbon chain dibasic ester according to any one of claims 1 to 3 and 80-99.9999 wt.% of a substrate, wherein the water activity value of the substrate is less than or equal to 0.

7.

5. The composition for skin care according to claim 4, wherein The base is a water-in-oil (W / O) formulation, a water-in-silicone (W / Si) formulation, an anhydrous gel or a gel.

6. The composition for skin care according to claim 4, wherein The composition of the base includes vegetable oil, mineral oil, polyol, silane or any combination thereof.

7. A method for maintaining skin, wherein: The steps include applying the solid form of the ascorbic acid carbon chain dibasic ester formulation according to any one of claims 1 to 3 to the skin surface of an individual, wherein the weight percentage of the solid form of the ascorbic acid carbon chain dibasic ester added to the formulation is 0.0001 to 20 wt.%, based on the total weight of the formulation.

8. The method for maintaining skin according to claim 7, wherein: The formulation is in the form of one of the following: cream, lotion, gel, powder, and paste.

9. The method for maintaining skin according to claim 8, wherein: The formula has the function of protecting skin fibroblasts or keratinocytes from damage by ultraviolet rays.

10. The method for maintaining skin according to claim 7, wherein: The solid form of the ascorbic acid carbon chain dibasic ester has the use of promoting skin fibroblasts or keratinocytes to produce collagen.

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