CN114010519A

CN114010519A - A method for improving stability of p-hydroxyacetophenone in cosmetic composition

Info

Publication number: CN114010519A
Application number: CN202111305348.8A
Authority: CN
Inventors: 赵仕芝; 娄菲
Original assignee: Yang Sheng Tang Shanghai Cosmetic R & D Co ltd
Current assignee: Yang Sheng Tang Shanghai Cosmetic R & D Co ltd
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2022-02-08
Also published as: TW202319039A; WO2023078108A1; TWI830456B

Abstract

The present invention relates to a method for improving the stability of p-hydroxyacetophenone in a cosmetic composition, which comprises adding a pH stabilizer to a cosmetic composition containing p-hydroxyacetophenone to maintain the pH of the composition stable, thereby improving the stability of p-hydroxyacetophenone in the cosmetic composition, which significantly alleviates the problem of discoloration (yellowing) of the cosmetic composition due to the instability of p-hydroxyacetophenone. Wherein the pH stabilizer is any substance known in the art that can stabilize the pH of the cosmetic composition, for example, a pH buffer pair, and an agent that can slowly release an acid by hydrolysis to stabilize the pH of the cosmetic composition.

Description

A method for improving stability of p-hydroxyacetophenone in cosmetic composition

Technical Field

The present invention relates to a method for improving the stability of p-hydroxyacetophenone in a cosmetic composition, which comprises adding a pH stabilizer to a cosmetic composition containing p-hydroxyacetophenone to maintain the pH of the composition stable, thereby improving the stability of p-hydroxyacetophenone in the cosmetic composition, which significantly alleviates the problem of discoloration (yellowing) of the cosmetic composition due to the instability of p-hydroxyacetophenone. Wherein the pH stabilizer is a substance known in the art to stabilize the pH of the cosmetic composition, including, for example, a pH buffer pair, an agent that slowly releases an acid by hydrolysis to stabilize the pH of the cosmetic composition, or a mixture thereof.

Background

The p-hydroxyacetophenone is a natural plant extract, is naturally present in stem and leaf of Artemisia scoparia of Compositae, and root of Artemisia capillaris, Asclepiadaceae, and radix Tylophorae Yunnanensis, is white to off-white flaky solid, and has molecular formula C₈H₈O₂The structure is as follows:

p-hydroxyacetophenone has the functions of clearing away damp-heat, promoting bile flow and removing jaundice, has good curative effect and auxiliary curative effect on eyeball jaundice caused by hepatitis and other reasons, and is commonly used for preparing cholagogue. P-hydroxyacetophenone also has multiple effects of oxidation resistance, irritation resistance, bacterial inhibition and the like, and is often used as a preservative synergist in cosmetics. The antioxidant and antibacterial properties of the antibacterial agent are both derived from hydroxyl, and the antibacterial agent is effective to fungi, has strong killing capability to aspergillus niger and also has a certain inhibiting effect to pseudomonas aeruginosa. Meanwhile, the p-hydroxyacetophenone is mild and safe, and has good compatibility with cosmetics, so that the using amount of the p-hydroxyacetophenone in the cosmetics is increased year by year.

When p-hydroxyacetophenone is used in cosmetics, it is usually dissolved in an alcohol solution by heating and then dissolved in water. However, even at normal temperature, p-hydroxyacetophenone is not stable in an alcohol solution or an aqueous solution, resulting in problems of discoloration of the solution and simultaneous upward shift in pH. Moreover, under the condition of light or high temperature, the instability phenomenon is more remarkable, and becomes a main problem in the application of the cosmetic.

To solve this problem, there are generally two approaches in the prior art. One is to compound p-hydroxyacetophenone and other antiseptic components. Another is to try to keep p-hydroxyacetophenone stable, thereby avoiding the problems of discoloration and pH drift upward, for example CN111937874A alleviates the discoloration problem caused by p-hydroxyacetophenone in alcohol solutions by using an antioxidant as a stabilizer; however, this method has a problem in that the antioxidant itself is generally very easily oxidized, for example, vitamin C used in this application, which shows the best effect, although it is relatively stable in an alcohol solution, is difficult to exert its effect of stabilizing p-hydroxyacetophenone again when it is applied to an aqueous cosmetic composition because vitamin C itself is very easily oxidized in an aqueous solution, thereby making the practical application of this method limited.

Therefore, there is a need for a method that can truly solve the problem of stability of p-hydroxyacetophenone in cosmetic compositions, thereby exerting the preservative enhancing effect of p-hydroxyacetophenone in cosmetic compositions.

Brief description of the drawings

FIG. 1 is a photograph of the appearance of compositions A-I after storage for 4 weeks initially and under various conditions.

Fig. 2 is a photograph of the appearance of compositions N and O after storage for 4 weeks initially and under various conditions.

FIG. 3 is a photograph of the appearance of compositions J-M after storage for 4 weeks initially and under various conditions.

Disclosure of Invention

The inventor finds that the stability of the p-hydroxyacetophenone in the cosmetic composition can be improved by adopting the pH stabilizer, so that the yellowing problem of the cosmetic composition caused by the instability of the p-hydroxyacetophenone can be remarkably relieved.

Accordingly, in one aspect, the present invention provides a method for improving the stability of p-hydroxyacetophenone in a cosmetic composition, which comprises adding a pH stabilizer to a cosmetic composition containing p-hydroxyacetophenone such that the pH of the composition remains stable throughout the shelf life (typically 3 years) and the method of the present invention allows the pH of the cosmetic composition not to drift upward significantly even under light or high temperature conditions for a considerable period of time.

In another aspect, the present invention relates to the use of a pH stabilizer in a cosmetic composition comprising p-hydroxyacetophenone for improving the stability of p-hydroxyacetophenone.

In a further aspect, the present invention provides a stable cosmetic composition comprising p-hydroxyacetophenone and a pH stabilizer, which does not yellow over time during the entire shelf life (typically 3 years).

The pH stabilizer is a substance known in the art that stabilizes the pH of the cosmetic composition to prevent the pH of the composition system from significantly shifting with the lapse of storage time, for example, a pH buffer pair, an agent that slowly releases an acid by hydrolysis to stabilize the pH of the cosmetic composition (simply referred to as "an agent that slowly releases an acid by hydrolysis").

The pH buffering pairs are those known in the art, including mixtures of weak acids and salts thereof. The weak acids include organic acids including, for example, acetic acid, levulinic acid, citric acid, lactic acid, phthalic acid, and the like, and inorganic acids including, for example, carbonic acid, phosphoric acid, metaphosphoric acid, sulfurous acid, hydrofluoric acid, hydrosulfuric acid, hypochlorous acid, and the like. The salt may be an alkali metal salt, for example, a sodium salt, a potassium salt. preferred examples of pH buffer pairs include, for example, sodium levulinate-levulinate, sodium/potassium citrate-citrate, and sodium/potassium lactate-lactate, and the like.

In addition, the pH buffer pair may also be an acid salt of a polybasic weak acid and its corresponding secondary salt, including, for example, sodium dihydrogen phosphate-disodium hydrogen phosphate, sodium hydrogen carbonate-sodium carbonate, and sodium dihydrogen citrate-disodium hydrogen citrate, and the like.

Based on the prior art, one skilled in the art can control the ratio of the two substances in the pH buffer pair. For example, typically the molar ratio of weak acid to its salt is about 0.5:1.0 to 3.0:1.0, preferably about 1:1, and the molar ratio of the acid salt of the polybasic weak acid to its corresponding secondary salt is about 0.5:1.0 to 3.0:1.0, preferably about 1: 1.

The agents which slowly release acid by hydrolysis and thereby stabilize the pH of the cosmetic composition are those known in the art and include, for example, small molecule lactones and/or esters. Specific examples include, for example, gluconolactone, γ -nonalactone, pantolactone, glucoheptonolactone, triethyl citrate, and the like.

In the present invention, each of the above pH buffering pairs and each of the above agents which slowly releases an acid by hydrolysis may be used alone or in combination.

The pH stabilizer is present in the cosmetic composition in an amount such that the pH of the cosmetic composition does not drift significantly upward over the shelf life (typically 3 years). Typically, the pH stabilizer is present in the cosmetic composition in an amount of about 0.01 to 3%, preferably about 0.05 to 2%, more preferably about 0.1 to 1%, based on the total weight of the cosmetic composition.

As is known in the art, the pH of cosmetic compositions is generally from about 4 to about 7, preferably from about 5 to about 7. In the present invention, the pH of the cosmetic composition can be stabilized in the above range throughout the shelf life by using the pH stabilizer. Typically, the shelf life of a cosmetic composition is about 3 years at ambient temperature (i.e., room temperature, typically about 20-25 ℃). Furthermore, the pH of the cosmetic composition can be kept stable for a considerable period of time by using the pH stabilizer even under illumination (e.g., placed on a window sill exposed to natural light, or placed in a standard light box) or at elevated temperature (e.g., above room temperature, such as about 30-60 ℃), for example, the pH of the cosmetic composition remains stable for 4 weeks under accelerated conditions of about 48 ℃ and about 60 ℃, without significant discoloration, as shown in the examples below.

In the cosmetic composition containing p-hydroxyacetophenone, the content of p-hydroxyacetophenone is usually about 0.01 to 1%, preferably about 0.05 to 0.8%, more preferably about 0.1 to 0.6%, based on the total weight of the cosmetic composition.

The cosmetic composition containing p-hydroxyacetophenone optionally contains various ingredients commonly used in cosmetics, including active ingredients, vehicles, surfactants, adjuvants, and the like, which are known to those skilled in the art, in addition to p-hydroxyacetophenone and a pH stabilizer, and the type and amount thereof can be specifically selected as needed.

The vehicle may be a diluent, dispersant or carrier, etc., all of which are known in the art, and the type and amount of which may be selected by one of skill in the art as desired, including, but not limited to, ethanol, dipropylene glycol, propylene glycol, butylene glycol, pentylene glycol, etc.; in the compositions of the present invention, the vehicle comprises about 1-20% of the total weight of the usual ingredients.

Such active ingredients include, for example, emollients, humectants, skin conditioning agents, and the like. Wherein the emollient includes, but is not limited to, one or more of tri (ethyl hexanoate), caprylic/capric triglyceride, shea butter, cetyl alcohol, dimethicone, pentaerythritol tetra (ethyl hexanoate), olive oil, grape seed oil, meadowfoam seed oil, avocado oil, corn oil, squalane, dioctyl carbonate, isopropyl myristate, hydrogenated polydecene, sunflower seed oil, isohexadecane, jojoba seed oil, lanolin, paraffin, microcrystalline wax, beeswax, and the like; in the cosmetic composition of the present invention, the emollient represents 0 to 50% by weight of the total weight of the usual ingredients.

The humectant includes but is not limited to one or more of birch juice, glycerol, betaine, glyceryl polyether-26, trehalose, sucrose, propylene glycol, 1, 2-pentanediol, mannitol, rhamnose, raffinose, erythritol, xylitol, urea, polyethylene glycol-8, polyethylene glycol-32, methyl glucitol polyether-10, methyl glucitol polyether-20, PEG/PPG-17/6 copolymer, sodium polyglutamate, hydrolyzed sclerotium rolfsii gum, pullulan, tremella polysaccharide, sodium polyglutamate, glycerol glucoside, PPG-10 methyl glucose ether, PPG-20 methyl glucose ether, etc.; in the cosmetic composition of the present invention, the humectant constitutes about 0.1 to 30% by weight of the total weight of the conventional ingredients.

The skin conditioning agent includes, but is not limited to, one or more of phytosterol/octyldodecanol lauroyl glutamate, hydrolyzed sodium hyaluronate, acetyl phytosphingosine, turmeric root extract, ceramide 2, ceramide 3, cholesterol, kojic acid, ascorbic acid, ascorbyl glucoside, arbutin, tranexamic acid, niacinamide, birch bark extract, acetyl phytosphingosine, resveratrol, Pterocarpus marsupium bark extract, Coleus forskohlii root extract, pepper seed extract, ubiquinone, bisabolol, ascorbyl tetraisopalmitate, pyridoxine dicaprylate, pyridoxine dipalmitate, retinol palmitate, and the like. The skin conditioner can be used for moisturizing, anti-wrinkle, spot removal, acne removal, oil control, etc., and generally, in the cosmetic composition of the present invention, the skin conditioner is about 0 to 50% by weight of the total weight of the commonly used ingredients.

The surfactant may be any type of surfactant commonly used in cosmetics. For reducing the surface tension of the interface, for the purpose of cleaning, emulsifying, stabilizing the system, it may be any type of surfactant commonly used in cosmetics, the type and amount of which may be selected by the skilled person as desired. For example, the surfactant may include, but is not limited to, fatty acid soaps (e.g., sodium laurate, sodium palmitate, etc.), higher alkyl sulfates (e.g., sodium lauryl sulfate, etc.), N-acyl sarcosines (e.g., sodium lauroyl sarcosinate, etc.), higher fatty acid amide sulfonates (e.g., sodium lauryl methyl taurate, etc.), alkylbenzene sulfonates, higher fatty acid ester sulfates (e.g., sodium hardened coconut fatty acid glycerol sulfate, etc.), N-acyl glutamates, lauryl dimethylaminoacetic acid betaine, alkyl betaines, amido betaines, sorbitan fatty acid esters (e.g., sorbitan monooleate, sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate) One or more of glycerol polyglycerin fatty acid esters (e.g., glycerol mono erucate, glycerol sesquioleate, glycerol monostearate malate, etc.), PEG-fatty acid esters (e.g., PEG-distearate, ethylene glycol distearate, etc.), PEG-alkyl ethers (e.g., PEG-2-octyldodecyl ether, etc.), sucrose fatty acid esters, and the like. The amount of surfactant present in the composition is known in the art. Typically, in the cosmetic compositions of the present invention, the surfactant comprises from about 0% to about 50% by weight of the total weight of the conventional ingredients.

Such adjuvants include, but are not limited to, surfactants, emulsifiers, thickeners, preservatives, fragrances, pH adjusting agents, and the like. Among these, emulsifiers include, but are not limited to: one or more of PEG-60 hydrogenated castor oil, glyceryl stearate/PEG-100 stearate, sorbitan olivetoleate, steareth-21, PPG-13-decyltetraeth-24, cetearyl glucoside, polyglyceryl-10 stearate, polyglyceryl-10 myristate, polyglyceryl-10 dioleate, and the like; typically, in the cosmetic compositions of the present invention, the emulsifier comprises from about 0% to about 10% by weight of the total weight of the conventional ingredients.

Such thickeners include, but are not limited to: one or more of carbomer, xanthan gum, SIMUGEL EG, acacia, polyethylene glycol-14M, polyethylene glycol-90M, succinoglycan, hydroxyethyl cellulose, hydroxypropyl cellulose, etc.; typically, in the compositions of the present invention, the thickening agent comprises from about 0% to about 10% by weight of the total weight of the conventional ingredients.

Preservatives that can be used in the present invention are not limited and are known in the art and include, but are not limited to, one or more of methylparaben, propylparaben, phenoxyethanol, benzyl alcohol, phenylethyl alcohol, potassium sorbate, sodium benzoate, chlorphenesin, and the like, as well as other preservative enhancers such as the commonly used preservatives of pentanediol, hexanediol, octanediol, and the like; typically, in the compositions of the present invention, the preservative comprises about 0.01 to 2% of the total weight of the commonly used ingredients.

There is no limitation on the pH adjusting agents that can be used in the present invention, which are known in the art, including but not limited to: one or more of citric acid, sodium citrate, arginine, etc. The type and amount can be specifically selected by those skilled in the art as desired.

The cosmetic compositions of the present invention may be prepared by any suitable method known in the art. For example, it can be prepared by using a vessel such as a dissolving tank, an emulsifying pot, a disperser, a transfer pump, etc., which are generally used in the cosmetic field. The preparation method comprises putting water soluble substance into water phase dissolving kettle, putting oil soluble substance into oil phase dissolving kettle, and heating the two kettles to about 80 deg.C respectively, wherein the raw material easy to agglomerate can be pre-dispersed with disperser. After the dissolution is finished, the oil phase and the water phase are conveyed into an emulsifying pot, and homogenized and emulsified for about 5-15 minutes. After emulsification is finished, the temperature of the material body is reduced to normal temperature, essence, preservative and the like are optionally added, and the pH of the product is adjusted as required. After the relevant detection indexes are qualified, the products can be filled and delivered. The preparation method can be deleted or adjusted according to the requirements of the preparation formulation, and can be used for preparing various preparation formulations such as water, emulsion, ointment, cream or gel and the like according to the requirements.

Examples

The present invention will be described in further detail with reference to examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All such substitutions and modifications will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.

Example 1: preparation and examination of the pH stability and color stability of p-hydroxyacetophenone-containing cosmetic compositions A (without addition of a pH stabilizer) and B-H (with addition of different and/or different concentrations of a pH stabilizer)

The formulations of cosmetic compositions A-I are shown in Table 1 below.

TABLE 1

Wherein levulinic acid (50% in water) is from the supplier suma; sodium levulinate (powder) was purchased from Wuhan La Na pharmaceutical chemicals. Gluconolactone is derived from the supplier family europeania. Disodium hydrogen phosphate and sodium dihydrogen phosphate were obtained from the alatin biochemical technology.

The preparation process of the cosmetic composition comprises the following steps:

(1) adding 1, 2-pentanediol into p-hydroxyacetophenone, heating to 80 ℃, fully dissolving and uniformly mixing;

(2) heating water to 80 ℃, then sequentially adding glycerol, betaine and methyl hydroxybenzoate, and stirring until the mixture is uniformly dissolved;

(3) mixing the above mixture obtained in (1) and (2), keeping at 80 deg.C for 30min, cooling to below 50 deg.C, adding levulinic acid/sodium levulinate, gluconolactone and/or disodium hydrogen phosphate/sodium dihydrogen phosphate, or arginine, stirring, and discharging.

To investigate the pH stability and color stability of the pH stabilizer on the p-hydroxyacetophenone-containing cosmetic compositions, the initial pH of each cosmetic composition was first tested separately and the appearance thereof was photographed, see fig. 1; subsequently, each cosmetic composition was dispensed and left at room temperature, windowsill, light (25 ℃, visible light intensity 16000LX), high temperature (48 ℃ and 60 ℃) for 2 and 4 weeks, respectively, to examine the pH change and color change of the composition under different conditions, and the appearance after 4 weeks was photographed. The results are shown in table 2 below.

TABLE 2

From the above results, it can be seen that, as time goes on, the pH of the cosmetic composition a without the addition of the pH stabilizer drifts upward to different degrees under normal temperature (room temperature), windowsill, high temperature and illumination conditions, and the color thereof gradually changes from colorless transparency to yellow or even dark brown, as shown in fig. 1; in contrast, cosmetic compositions B-I with the addition of a pH stabilizer exhibited no significant change in pH under various conditions, and also exhibited no significant change in color appearance, see FIG. 1. The results show that the pH stabilizer significantly improves the stability of p-hydroxyacetophenone in the cosmetic composition, thereby significantly alleviating the problems of color change and pH drift upward caused thereby.

Example 2: examination of the pH stability and color stability of cosmetic composition N (addition of a pH stabilizer) and cosmetic composition I (addition of an antioxidant)

To investigate the effect of the pH stabilizer on the color and pH stability of the p-hydroxyacetophenone-containing cosmetic composition, which was different from that of the antioxidant employed in prior art CN111937874A, cosmetic composition N of the present invention and control cosmetic composition O were prepared, the formulation of which is shown in table 3 below.

TABLE 3

The ingredients are%	Cosmetic composition N	Cosmetic composition O
			Water (W)	89.2	89.45
Glycerol	3	3
			Betaine	2	2
1, 3-propanediol	5	5
			P-hydroxyacetophenone	0.3	0.3
Hydroxy phenyl methyl ester	0.15	0.15
			Levulinic acid	0.1	0
Levulinic acid sodium salt	0.25	0
			Vitamin C	0	0.1

The initial pH of cosmetic compositions N and 0 was tested and the appearance photographed, see figure 2; cosmetic compositions N and 0 were then dispensed and placed under light at elevated temperature (60 ℃) for 2 weeks and 4 weeks, respectively, and the pH change and color change under different conditions were observed and tested. The results are shown in Table 4 below.

TABLE 4

From the above results, it can be seen that the pH of the cosmetic composition N added with the pH stabilizer did not change significantly under various conditions, and the color appearance thereof did not change significantly, see fig. 2; in contrast, cosmetic composition 0 with the added antioxidant vitamin C started to yellow significantly at high temperature and under light, and also slightly at room temperature, see fig. 2. The results show that the pH stabilizing effect of the pH stabilizer on the color and pH of the cosmetic composition containing p-hydroxyacetophenone is significantly superior to the technical scheme of using the antioxidant in the prior art patent.

Example 3: the effects of different pH stabilizers on the pH stability and color stability of p-hydroxyacetophenone-containing cosmetic compositions J-M were prepared and examined

The formulations of cosmetic compositions J-M are shown in Table 5 below.

TABLE 5

The initial pH of cosmetic compositions J-M was tested and the appearance photographed, see figure 3; each cosmetic composition was then dispensed and placed at room temperature, window sill, light and elevated temperature (48 ℃ and 60 ℃) for 2 weeks and 4 weeks, respectively, and observed and tested for pH change and color change under different conditions. The results are shown in Table 6 below.

TABLE 6

The above results show that the pH stabilizers within the scope of the present invention all significantly improved the stability of p-hydroxyacetophenone in the cosmetic composition without significant change in the color of the composition after 4 weeks, see fig. 3.

The technical solutions of the above-mentioned embodiments are preferred embodiments of the present invention, and in addition to the above, the pH stabilizer of the present invention can be applied to the improvement of color stability of various cosmetics such as essence, milk, cream, foundation, sunscreen, etc. to which p-hydroxyacetophenone is added, and several modifications and changes can be made without departing from the principle of the present invention, and these modifications and changes should be considered to be within the scope of the present invention.

Claims

1. A method for improving the stability of p-hydroxyacetophenone in a cosmetic composition comprises adding a pH stabilizer to a cosmetic composition containing p-hydroxyacetophenone.

2. The method of claim 1, wherein the pH stabilizing agent comprises a pH buffering pair, an agent that slowly releases an acid by hydrolysis, or a mixture thereof.

3. The method of claim 2, wherein the pH buffering pair comprises a mixture of a weak acid and its salt, an acid salt of a polybasic weak acid and its corresponding secondary salt, or a mixture thereof.

4. The method of claim 3, wherein the pH buffer pair is a mixture of weak acids and salts thereof, the weak acids comprising organic acids selected from the group consisting of acetic acid, levulinic acid, citric acid, lactic acid, and phthalic acid and inorganic acids selected from the group consisting of carbonic acid, phosphoric acid, metaphosphoric acid, sulfurous acid, hydrofluoric acid, bisulfic acid, and hypochloric acid, and the salts comprising alkali metal salts.

5. The method of claim 4, wherein the pH buffered pair comprises sodium levulinate, sodium/potassium citrate-citrate, sodium/potassium lactate, or a mixture thereof.

6. The method of claim 3, wherein the pH buffer pair is an acid salt of a weak polybasic acid and its corresponding secondary salt comprising sodium dihydrogen phosphate-disodium hydrogen phosphate, sodium hydrogen carbonate-sodium carbonate, sodium dihydrogen citrate-disodium hydrogen citrate, or mixtures thereof.

7. The method according to any one of claims 3-6, wherein the molar ratio of the two substances in the pH buffered pair is 0.5:1.0-3.0:1.0, preferably 1: 1.

8. The method of claim 2, wherein the agent that slowly releases acid by hydrolysis comprises small molecule lactones, esters, or mixtures thereof.

9. The method of claim 8, wherein the agent that slowly releases acid by hydrolysis comprises gluconolactone, γ -nonanolactone, pantolactone, glucoheptonolactone, triethyl citrate, or mixtures thereof.

10. The method according to any one of claims 1 to 9, wherein the pH stabilizer is present in the cosmetic composition in an amount of 0.01 to 3%, preferably 0.05 to 2%, more preferably 0.1 to 1%, based on the total weight of the cosmetic composition.

11. The method according to any one of claims 1-10, wherein the pH stabilizer maintains the pH of the composition between 4 and 7, preferably between 5 and 7, throughout the shelf life.

12. The method according to any one of claims 1 to 11, wherein the content of p-hydroxyacetophenone in the cosmetic composition is 0.01 to 1%, preferably 0.05 to 0.8%, more preferably 0.1 to 0.6%, based on the total weight of the cosmetic composition.

Use of a pH stabilizer in a cosmetic composition comprising p-hydroxyacetophenone to increase the stability of p-hydroxyacetophenone.

14. The use of claim 13, wherein the pH stabilizing agent comprises a pH buffering pair, an agent that slowly releases acid by hydrolysis, or a mixture thereof.

15. The use according to claim 14, wherein the pH buffering pair comprises a mixture of a weak acid and its salt, an acid salt of a polybasic weak acid and its corresponding secondary salt, or a mixture thereof.

16. The use of claim 15, wherein the pH buffer pair is a mixture of weak acids and salts thereof, the weak acids comprising organic acids selected from the group consisting of acetic acid, levulinic acid, citric acid, lactic acid, and phthalic acid and inorganic acids selected from the group consisting of carbonic acid, phosphoric acid, metaphosphoric acid, sulfurous acid, hydrofluoric acid, bisulfic acid, and hypochloric acid, and the salts comprising alkali metal salts.

17. The use of claim 16, wherein the pH-buffering pair comprises sodium levulinate, sodium/potassium citrate-citrate, sodium/potassium lactate, or a mixture thereof.

18. The use of claim 15, wherein the pH buffer pair is an acid salt of a weak polybasic acid and its corresponding secondary salt comprising sodium dihydrogen phosphate-disodium hydrogen phosphate, sodium hydrogen carbonate-sodium carbonate, sodium dihydrogen citrate-disodium hydrogen citrate, or a mixture thereof.

19. Use according to any one of claims 14 to 18, wherein the molar ratio of the two substances in the pH buffering pair is 0.5:1.0-3.0:1.0, preferably 1: 1.

20. Use according to claim 14, wherein the agent which slowly releases acid by hydrolysis comprises small molecule lactones, esters, or mixtures thereof.

21. Use according to claim 20, wherein the agent which slowly releases acid by hydrolysis comprises gluconolactone, γ -nonanolactone, pantolactone, glucoheptonolactone, triethyl citrate, or mixtures thereof.

22. Use according to any one of claims 13 to 21, wherein the pH stabilizer is present in the cosmetic composition in an amount of from 0.01 to 3%, preferably from 0.05 to 2%, more preferably from 0.1 to 1%, based on the total weight of the cosmetic composition.

23. Use according to any of claims 13 to 22, wherein the pH stabilizer maintains the pH of the composition between 4 and 7, preferably between 5 and 7, throughout the shelf life.

24. Use according to any one of claims 13 to 23, wherein the content of p-hydroxyacetophenone in the cosmetic composition is 0.01 to 1%, preferably 0.05 to 0.8%, more preferably 0.1 to 0.6%, based on the total weight of the cosmetic composition.

25. A stable cosmetic composition comprising p-hydroxyacetophenone and a pH stabilizer, wherein the pH stabilizer comprises a pH buffering pair, an agent that slowly releases acid by hydrolysis, or a mixture thereof.

26. The composition of claim 25, wherein the pH buffering pair comprises a mixture of a weak acid and its salt, an acid salt of a polybasic weak acid and its corresponding secondary salt, or a mixture thereof.