Compositions and non-therapeutic uses of combinations for targeted alteration of skin flora

Abstract

The present invention relates to a composition and non-therapeutic use of a combination for targeted alteration of skin flora, said composition comprising levulinic acid and anisic acid. The formulations according to the invention are particularly suitable for use on the skin. The preparation shows a selective antibacterial effect on skin by specifically resisting anaerobic bacteria of skin flora, and almost has no or no bactericidal effect on aerobic bacteria. Thus, the compositions according to the invention are suitable for non-therapeutic uses of compositions and combinations for targeted alteration of skin flora.

Description

[0001] This divisional application is a divisional application of a Chinese invention patent application with an application date of November 20, 2020, an entry date into the Chinese national phase of April 20, 2022, a PCT application number of PCT / EP2020 / 082863, a national application number of 202080073470.4, and an invention title of "Cosmetic preparation with anisic acid and levulinic acid having selective antimicrobial activity". Technical Field

[0002] The present invention relates to the non-therapeutic use of compositions and combinations comprising agents for the targeted modulation of the skin microbiota. The compositions comprise levulinic acid and anisic acid. The preparations according to the invention are particularly suitable for use on the skin. The preparations exhibit a selective antibacterial effect on the skin by specifically counteracting anaerobic bacteria in the skin microbiota, while they have little or no bactericidal effect on aerobic bacteria. Accordingly, the compositions according to the invention are suitable for cosmetic skin care and also for the dermatological treatment of certain skin diseases such as acne. Background Art

[0003] The human skin microbiome is a complex mixture of different microbial populations: anaerobic bacteria, such as Cutibacterium acnes (C. acnes), colonize the skin in close proximity to aerobic bacteria (such as Staphylococcus epidermidis (S. epidermidis) and Staphylococcus hominis (S. hominis)) and fungi.

[0004] The interaction between S. epidermidis and C. acnes is known to be particularly important for skin health. S. epidermidis is a spherical Gram-positive bacterium that grows aerobically and is catalase-positive and coagulase-negative. C. acnes is a Gram-positive bacterium that grows anaerobically. It is assumed that these two microorganisms occur in a relatively stable balance on healthy skin, and that a disturbance of this balance, so-called dysbiosis, can have a negative impact on the skin condition by causing skin blemishes and even skin diseases or at least promoting their development. Thus, for the treatment or prevention of such skin blemishes or skin diseases, it is particularly important to provide agents by means of which the ratio of anaerobic to anaerobic microorganisms in the skin microbiota, in particular the ratio of S. epidermidis to C. acnes, can be specifically modulated. Since in particular the enhanced growth of anaerobic bacteria such as C. acnes may be associated with the development of skin diseases, there is a particular need for preparations that selectively counteract the activity of anaerobic bacteria.

[0005] Anisic acid is a methoxylated benzoic acid (4-methoxybenzoic acid), which is considered to have antibacterial effects and also anti-inflammatory and antifungal effects. Anisic acid is especially used as a preservative in cosmetics to prevent products from being contaminated by bacteria or fungi. For this purpose, anisic acid is added to these products in an amount of 0.05 - 0.3%.

[0006] Levulinic acid, also known as 4-oxopentanoic acid or 4-oxovaleric acid, is a compound belonging to γ-keto acids. This acid is internationally known as "levulinic acid", and its salts are popular as fragrance additives in the field of skin care because their typical odor pleasantly reminds people of caramel or vanilla. In addition, the antibacterial and antifungal effects of levulinic acid are known. This also makes this substance meaningful as a skin care agent for unclean skin. Since levulinic acid is not declared as a preservative, it can ideally be used for the preservation of natural cosmetics. The use of levulinic acid as a preservative in cosmetics has been fully described, in which the substance is added to the product to be preserved in an amount of 0.3 - 1.0%.

[0007] Preservatives in cosmetics are often used to protect products from contamination by bacteria and fungi. The microbiological stability of cosmetics is a key factor for the shelf life and the protection of consumer health. In European cosmetics regulations, preservatives are defined as substances that are specifically or mainly used to inhibit the growth of microorganisms in cosmetics. The substances permitted for this purpose are listed in the corresponding positive list in Annex V of the EU KVO.

[0008] The use of anisic acid and levulinic acid as preservatives has been described in the prior art. EP 1 541 124A2 describes the synergistic effect between two active ingredients for preservation, namely anisic acid and monoglyceride of C6-14 fatty acids. This mixture should have antimicrobial activity that can be used for the preservation of cosmetic formulations. Therefore, a broad-spectrum antimicrobial agent appears in the formulation, and at the same time, it has good skin compatibility. The combination of levulinic acid, sodium salt of levulinic acid (sodium levulinate) and anisic acid for the preservation of cosmetic products is disclosed in EP 2 735 301A1.

[0009] Although anisic acid and levulinic acid have been widely used for the preservation of cosmetics, it has not been clear so far to use these substances to specifically change the composition of the skin flora. As described above, there is a need for cosmetic and dermatological compositions that can help improve the general condition and health of the skin by specifically interfering with the composition of the skin flora. At the same time, the composition should have good skin compatibility. Summary of the Invention

[0010] The present invention is based on the following surprising finding: anisic acid can be used in combination with levulinic acid to selectively reduce the concentration of anaerobic bacteria in the skin flora, in particular the concentration of Cutibacterium acnes. Accordingly, the present invention relates to the use of a combination of anisic acid and levulinic acid to reduce anaerobic bacteria on the skin while preserving aerobic bacteria. Thus, the combination according to the present invention allows for a selective antibacterial effect to be produced on the skin after application to the skin.

[0011] In a first aspect, the present invention relates to a composition for the targeted alteration of the skin flora, wherein the composition comprises:

[0012] (i) anisic acid or an antimicrobially active salt thereof, and

[0013] (ii) levulinic acid or an antimicrobially active salt thereof.

[0014] Satisfactory compositions preferably comprise anisic acid. However, anisates may also be used provided they have sufficient antimicrobial activity. Anisates suitable for use in the present invention preferably have an antimicrobial activity equivalent to at least 50% of the activity of anisic acid in the corresponding in vitro assay. This means that when equal amounts of anisic acid and anisate are used in an in vitro assay to determine antimicrobial activity, the anisate must have at least half the antimicrobial activity compared to anisic acid. Salts suitable for use in the present invention are sodium anisate and potassium anisate.

[0015] Levulinates suitable for use in the present invention preferably have an antimicrobial activity equivalent to at least 50% of the activity of levulinic acid in the corresponding in vitro assay. This means that when equal amounts of levulinic acid and levulinate are used in an in vitro assay to determine antimicrobial activity, the levulinate must have at least half the antimicrobial activity compared to levulinic acid. Salts suitable for use in the present invention are sodium levulinate and potassium levulinate.

[0016] In particular, the present invention relates to a composition for the targeted alteration of the skin flora, wherein the composition comprises

[0017] (i) more than 0.3% (weight / weight) of anisic acid or an antimicrobially active salt thereof, and

[0018] (ii) more than 1.0% (weight / weight) of levulinic acid or an antimicrobially active salt thereof.

[0019] In a particularly preferred embodiment, the composition comprises at least 0.5% (w / w) of anisic acid or an antimicrobial active salt thereof, and at least 1.5% (w / w) of levulinic acid or an antimicrobial active salt thereof. Accordingly, the amount of anisic acid or anisate in the composition is preferably at least 0.75%, at least 1.0%, at least 1.5%, at least 2.0%, at least 2.5%, at least 3.0%, at least 3.5%, at least 4.5% or at least 5.0% (w / w). The amount of levulinic acid or levulinate in the composition is preferably at least 2.0%, at least 2.5%, at least 3.0%, at least 3.5%, at least 4.5% or at least 5.0% (w / w).

[0020] In other words, the composition of the invention preferably comprises 0.5 - 5.0% (w / w) of anisic acid or an antimicrobial active salt thereof, and 1.5 - 5.0% (w / w) of levulinic acid or an antimicrobial active salt thereof. Particularly preferred is a composition comprising 1.0 to 4.0% (w / w) of anisic acid or anisate and 2.0 to 4.0% (w / w) of levulinic acid or levulinate. More preferred is a composition comprising 1.5 to 3.0% (w / w) of anisic acid or anisate and 2.0 to 3.0% (w / w) of levulinic acid or levulinate. Even more preferred is a composition comprising 2.0 to 3.0% (w / w) of anisic acid or anisate and 2.5 to 3.0% (w / w) of levulinic acid or levulinate.

[0021] The composition according to the invention can exist as a single formulation or as components that are combined with each other immediately before application to the skin. In the latter-mentioned case, the above amount data apply to the composition resulting from the combination of the components immediately before application. The invention also includes such a composition: wherein the two antimicrobial active components, namely anisic acid or its salt and levulinic acid or its salt, exist as separate formulations, and the separate formulations are sequentially applied to the skin. The two antimicrobial active components can be applied to the skin at time intervals of about 5 minutes, 10 minutes, 15 minutes, 20 minutes, 24 minutes or 30 minutes.

[0022] The compositions of the present invention can exist in various forms. For example, preferred dosage forms are solutions, suspensions, water-in-oil (W / O) or oil-in-water (O / W) emulsions, or multiple emulsions such as water-in-oil-in-water (W / O / W) or oil-in-water-in-oil (O / W / O) emulsions, aqueous dispersions or lipid dispersions or aerosols. The compositions according to the invention preferably exist in the form of an emulsion which, in addition to the components with antibacterial activity, also contains other substances such as fats, oils, waxes and / or other fatty bodies, as well as water and one or more emulsifiers such as are commonly used for this type of preparation. Such emulsions can advantageously be formulated as creams or lotions. Furthermore, it is possible and advantageous to incorporate the combination of anisic acid and levulinic acid according to the invention into aqueous systems or surfactant preparations for cleansing the skin and / or hair.

[0023] Those skilled in the art are of course aware that, without the usual auxiliaries and additives, most cosmetic and therapeutic compositions are scarcely imaginable. These include, for example, thickeners, fillers, fragrances, dyes, emulsifiers, additional active ingredients such as vitamins or proteins, sunscreens, stabilizers, insect repellents, alcohol, water, salts, and substances with antimicrobial, proteolytic or keratolytic activity, etc., provided that their use does not significantly inhibit the antimicrobial activity of the combination according to the invention or otherwise run counter to it.

[0024] The combination of anisic acid and levulinic acid according to the invention can advantageously be incorporated into conventional cosmetic and dermatological preparations, which in turn can exist in various forms. The compositions can, for example, exist in the form of creams, lotions, gels, ointments, pastes or solid sticks.

[0025] The above compositions are particularly suitable for non-therapeutic, cosmetic and / or therapeutic treatment of the skin, in particular the facial skin of humans. In a specific embodiment, the present invention relates to a composition as described above for use in a method of treating skin diseases. The skin disease is preferably dermatitis. Treatment of acne (acne vulgaris) with the above composition is particularly preferred. The therapeutic effect of the composition according to the invention advantageously results from a targeted change in the concentration of anaerobic bacteria on the skin. The concentration of these anaerobic bacteria is reduced, while the concentration of anaerobic bacteria in the same habitat is not reduced or not significantly reduced. This results in a shift in the ratio of anaerobic to aerobic bacteria on the skin, in particular a shift in the ratio of Propionibacterium acnes to Staphylococcus epidermidis.

[0026] The compositions according to the invention are also suitable for non-therapeutic cosmetic use. Such non-therapeutic cosmetic use can be used for selectively reducing the number of anaerobic bacteria on the skin, in particular for selectively reducing the number of Cutibacterium acnes. In this way, skin blemishes can be eliminated or avoided. In particular, blockages of the sebaceous glands, such as those occurring in acne, can be avoided. Therefore, non-therapeutic cosmetic use can significantly improve the visual appearance of the skin. In another embodiment, the invention also relates to the non-therapeutic use of the compositions according to the invention as defined above in acne skin care preparations.

[0027] Within the scope of a therapeutic treatment or a non-therapeutic cosmetic treatment, the composition can be applied to the skin one or more times. In one embodiment, the composition according to the invention is formulated for daily application to the skin. In an alternative embodiment, the composition according to the invention is formulated for single application to the skin. Surprisingly, the combination of anisic acid and levulinic acid in the composition according to the invention acts selectively, i.e., reduces anaerobic bacteria such as Cutibacterium acnes on the skin and aerobic bacteria such as Staphylococcus epidermidis are not attacked or not significantly attacked.

[0028] An advantage of the composition according to the invention is its high antimicrobial selectivity. The composition specifically causes a significant reduction in the number of anaerobic bacteria, in particular Cutibacterium acnes, colonizing the skin. At the same time, the composition has no inhibitory effect or only a slight inhibitory effect on aerobic bacteria, in particular Staphylococcus epidermidis, and their numbers on the skin are not significantly reduced. As explained and Figure 1-2 shown in the examples described below, the use of the composition according to the invention results in a 90% reduction in anaerobic bacteria, while the aerobic bacteria even continue to increase during the study.

[0029] Currently preferred is that after application of the composition according to the invention, the number of anaerobic bacteria in a specific skin area is reduced by at least 50%, at least 60%, at least 70%, at least 80%, at least 90% or at least 95% compared to the number of cells in the relevant skin area before application of the composition. Also preferred is that the number of aerobic bacteria in this skin area is simultaneously reduced by at most 25%, at most 20%, at most 15%, at most 10%, at most 5% or less compared to the number of cells in the relevant skin area before application of the composition.

[0030] Currently, it is particularly preferred that after applying the composition according to the present invention, the number of Propionibacterium acnes in a specific skin area is reduced by at least 50%, at least 60%, at least 70%, at least 80%, at least 90% or at least 95% compared to the number of cells in the relevant skin area before applying the composition. It is also preferred that the number of Staphylococcus epidermidis in this skin area is simultaneously reduced by at most 25%, at most 20%, at most 15%, at most 10%, at most 5% or less compared to the number of cells in the relevant skin area before applying the composition.

[0031] The activity of the composition according to the present invention has been confirmed in various studies, which are described in the following examples. In the test, bacteria were obtained from the cheeks by swab technique and cultured under aerobic and anaerobic (i.e., reduced oxygen content) conditions. After 14 days of use, bacteria were extracted from the subjects again. After evaluating the data of all subjects, a surprising picture emerged. There was no abnormality in the aerobically cultured bacteria, while the number of bacterial cells in the anaerobically cultured bacteria decreased by more than 90% significantly after one week. This selective performance can be confirmed in further in vitro studies. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Showing the results of the ATA test for anaerobic culture;

[0033] Figure 2 Showing the results of the ATA test for aerobic culture;

[0034] Figure 3 Showing the applied pattern; and

[0035] Figure 4 and Figure 5 Showing the results of the suspension test. DETAILED DESCRIPTION

[0036] EXAMPLES

[0037] The following examples are intended to illustrate the present invention and not to limit it. Unless otherwise stated, all amounts, parts and percentages are based on the weight and total amount or total weight of the respective preparations and compositions.

[0038] Example 1: Preparation of Bacterial Suspension and Growth Experiment

[0039] Staphylococcus epidermidis (DSM 1798) was taken out from a cryotube (EN 12353), smeared on a CASO agar plate and cultured at 37 °C for 24 hours. Then the second generation was created. The second generation was inoculated into 10 ml of BHI medium and 5 g of glass beads (diameter 4 mm) and shaken for 3 minutes. Thereafter, the batch was adjusted to an OD600 of 0.1 and then diluted 1:10 with a diluent. Then this bacterial suspension was used for the growth assay.

[0040] Test - Growth test of Staphylococcus epidermidis

[0041] Add 10 μL of the bacterial suspension to each well of a 24 - well plate and dry it completely (for at least 45 minutes under a sterile workbench). After drying, pipette 10 mg of the preparation to be studied (see Table 1) and distribute it in the well using a T - spatula. The control group remains untreated. Store the plate without a lid in a wet incubator at 37 °C and 90% air humidity for the duration of the incubation period (6 hours / 24 hours). After the incubation time has ended, add 500 μL of rinsing buffer to each well and rinse in an ultrasonic bath for 1 minute. Add the obtained 100 μL of supernatant to 900 μL of neutralizer and then plate it on CASO agar using a spiral plater. Incubate the agar plate at 37 °C for 24 hours and then count the colonies using an I + L counter.

[0042] Streak Cutibacterium acnes (DSM 1897) from a cryotube (EN 12353) onto an agar plate (COST agar) and incubate at 37 °C in an anaerobic chamber for 5 days. Inoculate 10 ml of anaerobic medium in a CELLSTAR CELL reaction tube with this culture and incubate in an anaerobic chamber for 18 hours. Thereafter, adjust this batch to an OD600 of 0.5 and then dilute it 1:10 with anaerobic medium. Then use this bacterial suspension for the growth assay.

[0043] Test - Growth test of Cutibacterium acnes

[0044] Add 10 μL of the bacterial suspension to each well of a 24 - well plate and dry it completely (for at least 45 minutes under a sterile workbench). After drying, pipette 10 mg of the preparation to be studied (see Table 1) and distribute it in the well using a T - spatula. The control group remains untreated. Store the plate without a lid in an anaerobic chamber within a 37 °C incubator (lined with cellulose + 50 mL of water) for the duration of the incubation period (6 hours / 24 hours). After the incubation time has ended, add 500 μL of rinsing buffer to each well and rinse in an ultrasonic bath for 1 minute. Add the obtained 100 μL of supernatant to 900 μL of neutralizer and then plate it on COST agar using a spiral plater. Incubate the agar plate at 37 °C for 5 days and then count the colonies using an I + L counter.

[0045] In the evaluation, determine the reduction factor. The reduction factor is the factor by which the number of cells (CFU) at different time points is reduced compared to the T0 control group or to each other.

[0046]

[0047] Design the research design such that the antibacterial activity of the test preparation can be demonstrated by comparison with an untreated control group.

[0048] Table 1: Results of the Tested Formulations and Growth Tests

[0049]

[0050]

[0051] The counts showed that the number of aerobic Staphylococcus epidermidis was not affected or not significantly affected by the formulations containing anisic acid and levulinic acid. Only a small reduction factor was measured in the Staphylococcus epidermidis batches. In contrast, the number of anaerobic Cutibacterium acnes was significantly reduced by the formulations.

[0052] Example 2: ATA Test

[0053] The ATA test was used to determine the antibacterial effect of the cosmetic preparation after twice-daily use. The duration of the test was usually 1 week. The application of the test formulations and the measurement of activity took place at the relevant site of the consumer, namely the cheek. The target quantity was the number of bacteria of aerobic and anaerobic bacteria.

[0054] All subjects were pre-treated with the designated washing gel for 3 days. After rinsing the cheek, "Test formulation 5" described in Table 1 was applied according to the instructions. Then it was spread by a Floq swab. The application was carried out 3 x 10 in a defined pattern on an area of 5 cm x 5 cm on the cheek. The application pattern was as Figure 3 shown. During the sampling period, the Floq swab was immersed in the rinsing buffer, and the swab remained in the rinsing buffer after the third sampling. The solution was directly diluted, and each sample was plated on 2 agar plates by a spiral plate. Then the application was repeated at the corresponding designated time points, usually after 1 week. Finally, half of the agar plates were incubated under anaerobic conditions at 37 °C for 5 days, and the other half of the agar plates were incubated at 37 °C for 24 hours. Then the agar plates were evaluated using a counter.

[0055] The results of the ATA test were as Figure 1 and Figure 2 shown. Figure 1 The results of the anaerobic culture are shown. It can be seen that the cell number of anaerobic bacteria was significantly reduced by treatment with the test formulation containing a combination of anisic acid and levulinic acid. Figure 2 The results of the culture medium are shown, and this reduction in cell number was not seen in Figure 2 . On the contrary, an increase in cell number could even be recorded here. Figure 1 and Figure 2 Thus, it impressively shows the selective activity of the combination of anisic acid and levulinic acid according to the invention.

[0056] Example 3: Suspension Test

[0057] The effects of the formulations according to the invention were further investigated in tests with suspensions of Staphylococcus epidermidis and Cutibacterium acnes. Glycerol stock cultures of Staphylococcus epidermidis (DSM 1798) and Cutibacterium acnes (DSM 1897) established according to European Standard 12353 were stored in a refrigerator at 5 °C. The first generation was prepared from these liquid stock cultures. Here, the corresponding cultures were spread on agar plates (Cutibacterium acnes: COST agar, Staphylococcus epidermidis: COAST agar) using a sterile disposable inoculation loop and then incubated. The Cutibacterium acnes cultures were incubated at 37 °C for 5 days, while the Staphylococcus epidermidis cultures were incubated at 37 °C for 24 hours. Then, a second generation was generated from this first generation by picking several colonies with a sterile disposable inoculation loop and then spreading them on a new agar plate. The second generation was then incubated at the appropriate temperature for 5 days or 24 hours. The obtained second generation was then used for the suspension test.

[0058] To prepare the suspension, some colonies of the second generation were taken with a sterile inoculation loop and added to 10 mL of medium in an Erlenmeyer flask containing 5 g of glass beads and shaken gently for 3 minutes. Then, the approximate number of cells per milliliter was adjusted by the optical density (OD). The optical density was measured at 600 nm using an Eppendorf photometer. The obtained OD was adjusted to a value of approximately 0.8 (±0.01) and then diluted again 1:50. Using this dilution strategy, a cell number of approximately 1x10 6 was obtained.

[0059] 50 μL of the antimicrobial raw material solution and 450 μL of the medium were placed in a sterilized Eppendorf reaction vessel for testing the formulation (Cutibacterium acnes: anaerobic medium, Staphylococcus epidermidis: BHI medium). For the positive control group, 500 μL of the medium was provided. After adding 500 μL of the prepared culture suspension, 1:10 dilutions of all samples were prepared at different times (after 1 hour, 3 hours, and 6 hours). For the positive control group, the dilution was also prepared directly after adding the culture (0 minutes) and plated by spiral plating. During the entire test period, the specimens were stored in an Eppendorf shaker at 1000 rpm and 30 °C or 37 °C. For the 1:10 dilution, 900 μL of the neutralization medium was placed in an Eppendorf reaction vessel and 100 μL of the culture raw material suspension was added at the time of collection. After the test, all agar plates were placed in an incubator for incubation and evaluated on a counter after cultivation.

[0060] The results are as Figure 4 and Figure 5As shown, it can be seen that the use of anisic acid, levulinic acid, or a combination of the two substances has no significant effect on the growth of the aerobic bacterium Staphylococcus epidermidis. On the other hand, in the case of the anaerobic bacterium Cutibacterium acnes, the use of anisic acid or levulinic acid alone does not result in a reduction in the number of cells. However, the combined use results in a significant selective antimicrobial effect.

Claims

1. A composition for targeted alteration of skin flora, wherein the composition comprises: (i) more than 0.3% (weight / weight) of anisic acid or a salt thereof having antimicrobial activity, and (ii) more than 1.0% (weight / weight) of levulinic acid or a salt thereof having antimicrobial activity.

2. The composition according to claim 1, which comprises: (i) at least 0.75% (weight / weight) of anisic acid or a salt thereof having antimicrobial activity, and (ii) at least 1.5% (weight / weight) of levulinic acid or a salt thereof having antimicrobial activity.

3. The composition according to claim 2, which comprises: (i) 0.75 to 5.0% (weight / weight) of anisic acid or a salt thereof having antimicrobial activity, and (ii) 1.5 to 5.0% (weight / weight) of levulinic acid or a salt thereof having antimicrobial activity.

4. The composition according to any one of claims 1 to 3, wherein, the composition is in the form of a cream, lotion, gel, ointment, paste or solid stick.

5. The composition according to any one of claims 1 to 4, wherein, the composition is used in a method for treating skin diseases, particularly in a method for treating acne.

6. The non-therapeutic use of the combination of (i) anisic acid or a salt thereof having antimicrobial activity and (ii) levulinic acid or a salt thereof having antimicrobial activity for selectively reducing the number of anaerobic bacteria on the skin, wherein, the anaerobic bacteria are bacteria of the Cutibacterium acnes species, wherein the number of aerobic bacteria on the skin is not significantly reduced, wherein the aerobic bacteria are bacteria of the Staphylococcus epidermidis species, and wherein the combination is administered in the form of a single composition containing 0.01 to 5.0% (weight / weight) of anisic acid or a salt thereof having antimicrobial activity and 0.01 to 5.0% (weight / weight) of levulinic acid or a salt thereof having antimicrobial activity.

7. The non-therapeutic use according to claim 6, wherein, the skin is facial skin.

8. The non-therapeutic use according to claim 6 or 7, wherein, the two components of the combination are administered to the skin simultaneously or sequentially.

9. The non-therapeutic use according to any one of claims 6 to 8, wherein, the combination is administered in the form of a single composition containing 0.1 to 1.0% (weight / weight) of anisic acid or a salt thereof having antimicrobial activity.

10. The non-therapeutic use according to any one of claims 6 to 9, wherein, the combination is administered in the form of a single composition containing 0.1 to 1.0% (weight / weight) of levulinic acid or a salt thereof having antimicrobial activity.

11. The non-therapeutic use according to any one of claims 6 to 10, wherein, the combination of (i) anisic acid or a salt thereof having antimicrobial activity and (ii) levulinic acid or a salt thereof having antimicrobial activity is for non-therapeutic use in acne skin care.

Images