HYDROQUINONE STABILIZING COMPOSITION

Abstract

Provided in the present disclosure is a composition comprising hydroquinone or a derivative thereof as an active ingredient, and characterized in that the hydroquinone or the derivative thereof is stabilized by means of poloxamer. The composition of the present disclosure increases the soluble concentration of the hydroquinone or the derivative thereof, can have high melt stability without precipitation even at high concentration in water, can enhance storage stability by preventing oxidation reaction to external stimulations such as heat, oxygen and light, can prevent discoloration, and thus has reduced toxicity induced by an oxidation product of the hydroquinone and can reduce inflammatory response. Also, the composition of the present disclosure can enhance whitening efficacy by enhancing the skin permeability of the hydroquinone or the derivative thereof by means of micelles, and thus is useful for a whitening activity having hydroquinone or a derivative thereof as an active ingredient.

Claims

1. A composition comprising hydroquinone or a derivative thereof as an active ingredient, wherein the hydroquinone or a derivative thereof is stabilized using a poloxamer.

2. The composition of claim 1, wherein the poloxamer is a combination of two or more poloxamers.

3. The composition of claim 2, wherein the poloxamer is a combination of the first poloxamer and the second poloxamer, wherein the first poloxamer has the PPO molecular weight of about 1200-1800 g/mol and the PEO content percentage of about 30-80%, and the second poloxamer has the PPO molecular weight of about 3000-4500 g/mol and the PEO content percentage of about 30-80%.

4. The composition of claim 3, wherein the first poloxamer is poloxamer 188 and the second poloxamer is poloxamer 338, poloxamer 407 or a mixture thereof.

5. The composition of claim 1, wherein the derivative is hydroquinone monobenzyl ether, hydroquinone monomethyl ether, hydroquinone monoethyl ether, or mixtures thereof.

6. The composition of claim 1, wherein the composition comprises poloxamer micelles, and the external phase containing the micelles is a water phase.

7. The composition of claim 1, wherein the composition is for improving whitening.

8. The composition of claim 1, wherein the composition further comprises an antioxidant.

9. The composition of claim 3, wherein the first poloxamer and the second poloxamer are used in a weight ratio of 1:0.1 to 10.

10. The composition of claim 1, wherein the composition further comprise a hydrophilic solvent selected from polyethylene glycol, propylene glycol, dipropylene glycol, glycerin, 1,3-butanediol, isopropyl alcohol, or ethanol.

11. A method of stabilizing hydroquinone or a derivative thereof in a composition, characterized by that a poloxamer is added in the composition.

12. The method of claim 11, wherein the poloxamer is a combination of two or more poloxamers.

13. The method of claim 12, wherein the poloxamer is a combination of the first poloxamer and the second poloxamer, wherein the first poloxamer has the PPO molecular weight of about 1200-1800 g/mol and the PEO content percentage of about 30-80%, and the second poloxamer has the PPO molecular weight of about 3000-4500 g/mol and the PEO content percentage of about 30-80%.

14. The method of claim 13, wherein the first poloxamer is poloxamer 188 and the second poloxamer is poloxamer 338, poloxamer 407 or a mixture thereof.

15. The method of claim 11, wherein the derivative is hydroquinone monobenzyl ether, hydroquinone monomethyl ether, hydroquinone monoethyl ether, or mixtures thereof.

16. The method of claim 11, wherein the composition comprises poloxamer micelles, and the external phase containing the micelles is a water phase.

17. The method of claim 11, wherein the composition is for improving whitening.

18. The method of claim 11, wherein the composition further comprises an antioxidant.

19. The method of claim 13, wherein the first poloxamer and the second poloxamer are used in a weight ratio of 1:0.1 to 10.

20. The method of claim 11, wherein the composition further comprise a hydrophilic solvent selected from polyethylene glycol, propylene glycol, dipropylene glycol, glycerin, 1,3-butanediol, isopropyl alcohol, or ethanol.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0032] FIG. 1 is a schematic diagram of micelles in which hydroquinone is entrapped by poloxamer, a triblock copolymer composed of hydrophobic polyoxypropylene in the center and hydrophilic polyoxyethylene on both sides.

[0033] FIG. 2 is the experimental result showing the reduction in cytotoxicity of the stabilized hydroquinone.

[0034] FIG. 3 is the photographs of the experimental result showing the reduction in discoloration of the stabilized hydroquinone.

[0035] FIG. 4 is the test result of color difference showing the reduction in discoloration of the stabilized hydroquinone.

[0036] FIG. 5 is the result of applying Example 1 and Comparative Example 2 to pig skin.

[0037] FIG. 6 is the experimental result showing the increased skin delivery of the stabilized hydroquinone.

[0038] FIG. 7 is the result of confirming the change in melanin on the sectioned plane 3 days after applying Example 1, Comparative Example 1, and Comparative Example 2 to 3D skin.

[0039] FIG. 8 is the result showing the effect of the types of poloxamer on the stability and gelation of hydroquinone.

[0040] FIG. 9 is the result showing the effect of the contents of poloxamer on the stability of hydroquinone under the severe conditions.

MODE FOR INVENTION

[0041] Hereinafter, examples and the like will be described in detail to aid understanding of the present invention. However, the examples according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the following examples. Examples of the present invention are provided to more completely explain the present invention to those skilled in the art.

[0042] Formulation or Preparation of Example 1 and Comparative Examples 1 and 2

[0043] First, Example 1 according to the present invention, Comparative Example 1, and Comparative Example 2 were prepared according to the composition shown in Table 1 below.

TABLE-US-00001 TABLE 1 Material Comparative Component (Unit: weight %) Example 1 Example 1 or 2 Block copolymer 1 Poloxamer 188 10 0 (First poloxamer) Block copolymer Poloxamer 338 10 0 2(Second poloxamer) Antioxidant Sodium metabisulfite 0.5 0 Hydrophilic solvent Dipropylene glycol 6.6 6.6 Active ingredient Hydroquinone 4 4 Distilled water up to 100 up to 100

[0044] Example 1 is the composition comprising hydroquinone entrapped in the block copolymers. Comparative Example 1 is the composition comprising hydroquinone not entrapped in a block copolymer. Comparative Example 2 is the composition which comprises not entrapped hydroquinone and is discolored at 50° C. for 12 weeks.

[0045] Specifically, it was prepared as follows: Block copolymer 1 was added to a certain amount of distilled water according to the ratio shown in Table 1 while maintaining at 50˜60° C. After stirring at 1000 rpm until block copolymer 1 was completely dissolved, the mixture was cooled to a temperature of 10° C. Block copolymer 2 was slowly added to the cooled solution with stirring at room temperature to form micelles. Thereafter, bubbles were removed by vacuuming with a vacuum pump, and then the antioxidant and the hydrophilic solvent were added with stirring at room temperature. Thereafter, hydroquinone was added with stirring at 1200 rpm to entrap hydroquinone in the micelles (see FIG. 1).

[0046] In the Comparative Examples 1 and 2, the hydrophilic solvent and hydroquinone were mixed with stirring at 1000 rpm at room temperature according to the ratio as shown in Table 1 without the block copolymers.

[0047] For the Comparative Examples 3 and 4, the commercially available cream comprising hydroquinone was used. The Comparative Examples 2 and 4 were oxidized by storing at 50° C. for 12 weeks in order to evaluate the cytotoxic effect due to oxidation of hydroquinone.

Evaluation Example 1. Measurement of Cytotoxicity of the Stabilized Hydroquinone

[0048] By adding the compositions of Example 1 and Comparative Examples 1 to 4 to the culture medium of B-16 mouse melanoma cells, the cytotoxicity at the same concentration was measured using CCK-8 kit (Cell Counting Kit-8; Dojindo, Japan). B16 cells were seeded in a 96-well cell culture plate, and then treated so that the concentration of hydroquinone in the composition was 0, 0.6, 1.26, 2.5, 5, 10, 20, 40 and 80 μg/ml. After 48 hours CCK-8 solution was added. After 1 hour, the absorbance of the cell culture medium was measured at 405 nm to measure the cytotoxicity. The results are shown in FIG. 2.

[0049] As shown in FIG. 2, when assuming the viability of the untreated control cell group was 100%, the hydroquinone entrapped in the micelles using poloxamer (Example 1) showed 50% of cell viability at the concentration of 40 μg/ml. On the other hand, the hydroquinone dissolved in the aqueous phase without poloxamer (Comparative Examples 1 and 2) showed 40% or less of cell viability at the concentration of 10 μg/ml. In addition, the commercially available hydroquinone cream discolored by oxidation at 50° C. (Comparative Example 4) showed 50% of cell viability at the concentration of 10 μg/ml. These results suggest that the hydroquinone entrapped in the micelles using the poloxamer of the present invention has an effect of reducing toxicity in melanocytes.

Evaluation Example 2. Measurement of Discoloration of Stabilized Hydroquinone

[0050] The storage stability of Example 1 and Comparative Example 1 compositions was evaluated. After the test samples were stored at 50° C. for 12 weeks, the color difference was calculated. Before and after storage at 50° C. (0, 12 weeks), 100 μl of each composition was added to a 96-well opaque white plate, and then L value (lightness), a value (redness), and b value (yellowness) were measured with Chromameter CR-400 (Minolta, Japan) three times. The overall color difference is expressed as a value of ΔE=√ΔL.sup.2+Δa.sup.2+Δb.sup.2. The default value for color difference comparison was the value of the composition wherein the same amounts of hydroquinone and its solvent, water, were placed in a standard plate. The results are shown in FIGS. 3 and 4.

[0051] As shown in FIGS. 3 and 4, after 12 weeks at 50° C., the unentrapped hydroquinone of Comparative Example 1 had the higher value of color difference of 42. On the other hand, hydroquinone entrapped with the poloxamer of Example 1 had the color difference of 6, which was the similar value at the 0.sup.th week of Comparative Example 1. Therefore, it suggests that the storage stability can be increased by entrapping the hydroquinone in the micelles using the poloxamer of the present invention.

Evaluation Example 3. Evaluation of the Skin Delivery of the Stabilized Hydroquinone

[0052] The skin delivery of Example 1 and Comparative Example 1 compositions was evaluated. A skin permeability test was performed using porcine skin (pig skin) on the test samples. The receptor of the Franz diffusion cell was filled with 50% ethanol, and the porcine skin was placed between the donor and the receptor with the epidermis facing up (toward the donor) and the dermis facing down (toward the receptor). 0.1 ml of Example 1 and Comparative Example 1 compositions were applied to the skin and spread evenly. Thereafter, the skin tissues were recovered after being placed in a thermo-hygrostat for 18 hours. Only the skin tissues exposed to the compositions were used, and the stratum corneum, epidermal, and dermal layers were analyzed separately. For the stratum corneum, the stratum corneum tape (D-Squame standard sampling disc) was separated. The remained pig skin was heated at 70° C. for 15 seconds and then separated into the epidermal and dermal layers, and the hydroquinone present in each tissue layer was dissolved in 50% ethanol. The results are shown in FIGS. 5 and 6.

[0053] As shown in FIG. 6, hydroquinone entrapped with the two block copolymers of Example 1 had the skin permeability three times higher than that of Comparative Example 1 in the stratum corneum, epidermal, and dermal layers. It suggests that the hydroquinone-entrapped poloxamer micelles according to the present disclosure can also increase the delivery of hydroquinone to the skin.

Evaluation Example 4. Whitening Effect and Inflammation Evaluation of the Stabilized Hydroquinone in Artificial Skin

[0054] In order to compare the whitening effect of Example 1 with Comparative Examples 1 and 2, the 3D artificial skin composed of epidermis and melanocytes (Tego Science, Korea) was used. After treating the artificial skin with 50 mJ/cm.sup.2 of UVB, 25 μl of each composition was applied to the artificial skin. After culturing for 3 days, the whitening effect was measured by sectioning the 3D skin with a paraffin block, and inflammation was evaluated using the culture medium. The whitening effect was evaluated by the change in the amount of melanin. After staining melanin through Fontana-Masson staining and imaging with a microscope at 40× magnification, the amount of melanin was quantified using the ImageJ program. Inflammation was evaluated using the secretion amount of interleukin 1a, an inflammatory secretion factor, and the secretion amount of interleukin 1a in the culture medium was measured using an ELISA kit (R&D System, USA). Table 2 and FIG. 7 show the inhibitory effect of the melanin formation and inflammation evaluation results in 3D artificial skin.

TABLE-US-00002 TABLE 2 Pigmentation Inflammation N = 2 inhibitory effect evaluation (Image 30 spots) (vs UVB alone) (vs HQ 4%) UVB 0 — UVB + Comparative example 1 39.2% * 100% UVB + Comparative example 2 14.9% 116% UVB + Example 1 56.0% **  66% (* p < 0.05, ** p < 0.005)

[0055] As shown in Table 2 and FIG. 7, in the cases of Comparative Example 1 applied with non-entrapped hydroquinone and Comparative Example 2 applied with the discolored hydroquinone by storing at 50° C., the pigmentation inhibitory effect was approximately 39% and 15%, respectively. On the other hand, the Example 1 in which hydroquinone was stabilized by entrapping with the block copolymers showed a high pigmentation inhibitory effect of 56%. In addition, the result of interleukin 1a, an inflammatory factor, was also reduced by 34% in the case of the stabilized hydroquinone. It suggests that the hydroquinone stabilized in the micelles using the poloxamers of the present invention can increase the skin whitening effect and reduce side effects such as inflammation.

[0056] Evaluation of the Effects of Different Types of Poloxamers

[0057] The compositions comprising various poloxamers were prepared in the same manner as in Example 1 according to the formulation in Table 3 below.

TABLE-US-00003 TABLE 3 Material 2 types of 1 type of (Unit: weight %) poloxamers mixed poloxamer alone Poloxamer 1 10 20 Poloxamer 2 10 — Ascorbic acid 1 1 Dipropylene glycol 6.6 6.6 Hydroquinone 4 4 Distilled water up to 100 up to 100

[0058] Then, after being left at room temperature for 14 days, discoloration and gelation were evaluated, and the results are shown in FIG. 8. As shown in FIG. 8, the least discoloration was observed when poloxamer 188 was used as the first poloxamer and poloxamer 338 or 407 was mixed as the second poloxamer. In addition, when poloxamer 407 was used alone or mixed with poloxamer 338, solubilization was less desirable due to gelation.

[0059] Evaluation of Effects According to the Content of Poloxamer

[0060] As shown in Table 4 below, the compositions having the same formulation as in Example 1 and changing only the total content of poloxamer to 0-8% were prepared, wherein the first poloxamer (poloxamer 188) and the second poloxamer (poloxamer 338) maintained the weight ratio of 1:1.

TABLE-US-00004 TABLE 4 Material (Unit: wt %) #1 #2 #3 #4 #5 #6 #7 #8 Poloxamer 1 (Poloxamer 188) 0 1 1.25 1.5 2 2.5 3 4 Poloxamer 2 (Poloxamer 338) 0 1 1.25 1.5 2 2.5 3 4 Sodium metabisulfite 0.3 Dipropylene glycol 6 Hydroquinone 4 Distilled water up to 100

[0061] Afterwards, the stability over time was observed at 60° C., which is a somewhat severe condition, and the results are shown in FIG. 9. As shown in the FIG. 9, the compositions having 2.5 to 6% by weight of poloxamer were stable until 6 weeks, and the stability of the hydroquinone was better in the compositions having 2.5 to 5% by weight of poloxamer when used until 12 weeks or more. However, because these results are the results under the severe conditions, the results shows that the compositions having other contents may also have sufficient distribution stability under the room temperature.