WO2012130621A1

WO2012130621A1 - Use of cationic surfactants against acne

Info

Publication number: WO2012130621A1
Application number: PCT/EP2012/054540
Authority: WO
Inventors: Xavier Rocabayera Bonvila; Joan SEGUER BONVAVENTURA; Maria Teresa BELTRÁN PINA; Maria MINGUET BONVEHÍ
Original assignee: Laboratorios Miret, S.A.
Priority date: 2011-03-28
Filing date: 2012-03-15
Publication date: 2012-10-04

Abstract

The present invention relates to the use of a cationic surfactant derived from the condensation of fatty acids and esterified dibasic amino acid for the treatment of acne.

Description

USE OF CATIONIC SURFACTANTS AGAINST ACNE

Technical field

The present application relates to a novel use of cationic surfactants. Background art

Acne (or Acne vulgaris) is a multifactorial disease affecting the pilosebaceous glands. Four factors must co-exist at the same time, for this disease to appear: increased sebum production, folide hyperkeratinization, colonisation of the follicle by the microorganism Propionibacterium acnes, and liberation of inflammatory mediators in the follicle and surrounding dermis.

As explained above, acne is not only a microorganism-caused disease, but the proliferation of Propionibacterium acnes is one of the most important factors involved. This micro-organism is an anaerobic Gram-positive bacterium which is usually found on the skin and which is able to induce the hydrolysis of triglycerides from sebum and thus, the liberation of free fatty acids.

Among the drugs which have been traditionally used to treat acne, benzoyl peroxide, retinoids, and salicylic acid are quite common.

Benzoyl peroxide is a keratolytic and bactericidal agent (Bikowski J. et al., J. Clin. Aesthet. Dermatol., 2010, 3, 26-9; Duti! M., Skin Therapy, 2010, 15(10), 5-7). It is decomposed by skin cysteine, whereby active oxygen species are released into follicles which are efficient in eliminating keratin. However, it is a strong oxidant agent that can cause irritation, desiccation and desquamation of the skin.

Retinoids are vitamin A derivatives that increase skin cell turnover promoting the extrusion of the plugged material in the follicle. Like benzoyl peroxide these products can produce skin irritation as well.

Salicylic acid is less efficient than benzoyl peroxide and retinoids. Despite this fact, this product is one of the most widely used treatments particularly in patients who do not tolerate the use of the first ones due to their skin irritation potential.

Salicylic acid is more a keratolytic agent than a bactericidal agent.

Among the cosmetic preparations which are used to treat acne, it is possible to find lotions, creams, gels or toners among others.

Cationic surfactants are well-known in the art for a variety of different applications. Such cationic surfactants are derived from the condensation of fatty acids and esterified dibasic amino acids, according to the following formula (1 ):

where:

X- is Br-, Cl-, HSO₄- a counter ion derived from an organic or inorganic acid, or an anion on the basis of a phenolic compound;

Ft;: is a linear alkyi group derived from a saturated fatty acid or hydroxyacid from 8 to 14 carbon atoms bonded to the a-amino acid group through an amidic bond;

R₂: is a linear or branched alkyi chain from 1 to 18 carbon atoms or an aromatic group;

R₃: is

or

and n can be from 0 to 4. The organic acids which may be the source of the counter ion X- can be citric acid, lactic acid, acetic acid, fumaric acid, maleic acid, gluconic acid, propionic acid, sorbic acid, benzoic acid, carbonic acid, glutamic acid or other amino acids, lauric acid and fatty acids such as oleic acid and linoleic acid, whereas the inorganic acids can be phosphoric acid, nitric acid and thiocyanic acid.

The phenolic compound which may be the basis of the anion X- is for instance butylated hydroxyanisole (BHA) and the related butylated hydroxytoluene, tertiary butyl hydroquinone and parabens such as methylparaben, ethylparaben,

propylparaben and butylparaben.

LAE®, see formula (2) is a cationic surfactant with antimicrobial properties derived from natural building blocks: lauric acid and the amino acid L-arginine. This compound inhibits the proliferation of several micro-organisms including bacteria, fungi and yeasts by means of disturbance of the membrane potential, altering cell permeability and therefore inducing the loss of cell viability (Infante R. et al., International Journal of Cosmetic Science 1984; 6: 275-282). The chemical structure of LAE is described in the following formula (2):

The preparation of this product has been described in Spanish patent application ES-A-512643.

The metabolism of the above cationic surfactant of formula (2) in rats has been studied, these studies have shown a fast absorption and metaboiisation into naturally-occurring amino acids and the fatty acid lauric acid, which are eventually excreted as carbon dioxide and urea. Toxicological studies have demonstrated, that LAE© is completely harmless to animals and humans. Therefore, LAE® and related compounds are particularly suitable to be used in the preservation of all perishable food products. LAE® and related compounds are equally suitable for use in cosmetic products.

This compound of the formula (2) is remarkable for its inhibitory action over the proliferation of different microorganisms, such as bacteria, fungi and yeasts.

Since LAE® is a cationic surfactant, with a very mild eco-toxicological profile and- suitable for Ecocert formulations, it shows many advantages in terms of being aligned with the current market trends compared to the traditional anti-acne and dermopurifying actives.

Acne is a highly irritating disease which may lead to lasting effects on the skin. It is regularly occurring in adolescence but may continue in adults.

Disclosure of the invention

It is an object of the present invention to provide a novel method for the treatment of acne.

According to the present invention, this object is solved by providing the cationic surfactants according to the formula (1 ) for the treatment of acne.

More in particular, it is the solution according to the resent invention to provide preparations containing LAE® according to the above formula (2) for the treatment of acne.

The preparations containing the cationic surfactants, more in particular the preparations containing LAE® turned out to be effective in the treatment of acne and were well tolerated. Treatment with preparations of LAE® for 28 days was sufficiently long to observe an improvement of the problems observed on the skin. The use of the invention relates to cationic surfactants derived from the condensation of fatty acids and esterified dibasic amino acids, according to the following formula (1 ):

where:

X- is Br-, CI-, HSO₄- _, ^a counter ion derived from an organic or inorganic acid, or an anion on the basis of a phenolic compound;

Ri: is a linear aikyl group derived from a saturated fatty acid or hydroxyacid from 8 to 14 carbon atoms bonded to the α-amino acid group through an amidic bond;

R₂: is a linear or branched aikyl chain from 1 to 18 carbon atoms or an aromatic group;

R₃: is

and n can be from 0 to 4,

The organic acids which may be the source of the counter ion X- can be citric acid, lactic acid, acetic acid, fumaric acid, maleic acid, gluconic acid, propionic acid, sorbic acid, benzoic acid, carbonic acid, glutamic acid or other amino acids, lauric acid and fatty acids such as oleic acid and linoieic acid, whereas the inorganic acids can be phosphoric acid, nitric acid and thiocyanic acid. The phenolic compound which may be the basis of the anion X- is for instance butylated hydroxyanisoie (BHA) and the related butylated hydroxytoluene, tertiary butyl hydroquinone and parabens such as methy!paraben, ethylparaben,

propylparaben and butylparaben.

The most preferred compound of the above class of compounds is LAE® as provided in the above formula (2).

It is preferred to dissolve the compound of the formula (1 ), more in particular the preferred compound of formula (2), directly before use in one of the following preferred solvents of food grade: water, ethanol, propylene glycol, isopropyl alcohol, other glycols, mixtures of glycols and mixtures of glycols and water. If the treatment shall be performed at a specific pH value the use of a corresponding buffer solution may be recommendable. On the other hand the compound can be easily used as a solid.

According to the present invention, the anti-acne preparations of the cationic surfactants can be either water-based or anhydrous. Among the first ones, toners, lotions, gels or emulsions (like creams) can be found. In case of anhydrous preparations, those can be based on alcohol or can be pastes or masks. Masks can be formulated with or without water and are aimed to be used for overnight treatment.

The cationic surfactants may be applied as a composition against acne in cosmetic formulations such as: emulsions, lotions, toners, masks or gels among others where this anti-acne activity is claimed, at concentrations of from 0.0001 wt-% (w/w) up to 5 wt-% /(w/w). The preferred range is between 0.001 wt-% to 1 wt-%, most preferred 0.01 wt-% to 0.9 wt-% and most preferred 0.1 wt-% to 0.8 wt-%.

The effects of the present invention are illustrated through the following examples.

Examples-

Example 1. Aqueous solutions

Suspension Test

This test is based on a quantitative suspension test according to DIN EN 12054 (dilution-neutralization method).

Two different LAE® and salicylic acid concentrations were evaluated. The compositions which were assessed are displayed in table 2 below.

The suspension test was performed in aqueous solutions to assess the activity of LAE® and salicyclic acid against Propionibacterium acnes. Propionibacterium acnes (CECT 5684 / ATCC 6319) was grown under anaerobic conditions in Trypticase Soy broth up to 10⁸ CFU (Colony Forming Units) per mL.

Each test sample was inoculated with this culture at 1% (time zero) and an aliquot of 1 mL of each solution was removed at different times depending on the experiment requirements. 0.1 mL of the appropriate dilution was spread onto Trypticase Soy Agar (TSA) plates for counting using an spiral automatic spreader (Eddy Jet, lUL Instruments).

TSA plates were incubated at 37 ± 2°C for 48-72 hours under anaerobic conditions, and afterwards they were read with an automatic colony counter (Counter Flash 4.2, IUL Instruments).

The results expressed as log CFU/mL of test solution are provided in the table 3 below. The detection limit is 2 log CFU/g.

Table 2.

After inoculation with Propionibacterium acnes (8-7 log UFC/ml), the content of this micro-organism was analysed after several periods of time, as table below shows.

Table 3.

The results proved the surprising antimicrobial efficacy of LAE® against P. acnes, compared to salicylic acid.

Example 2.

Oil in water emulsions.

An anti-acne moisturising cream was prepared, with esters instead of oils as fatty phase, to be more suitable for consumers with oily skin.

As the active ingredients against acne LAE® and salicylic acid were chosen, at two different concentrations, 0.4% and 0.8%. The compositions which were assessed are displayed in table 4 below.

Table 4.

The results of the suspension test with P. acnes expressed as log CFU/mL of test solution are provided in the table 5 below. The detection limit is 2 log CFU/g.

Table 5.

Again, LAE® is much more effective than salicylic acid and kills the P. acnes population within 30 minutes.

Example 3.

Cosmetic acceptance questionnaire

18 panellists (8 females, 10 males) aged between 16 and 28 years and with oily and acne prone skin, evaluated some attributes of several cosmetic anti-acne formulations. The panellists were asked about several attributes. The volunteers used 0.5 mL (measured with a syringe) of the formulation twice a day, applying it over the whole face. Each formulation tested was evaluated by at least 6 volunteers. The treatment was performed during 28 consecutive days.

The samples 2, 2a and 2d described in example 2 were evaluated by the panel of 18 volunteers with oily and acne-prone skin (each formulation was evaluated by 6 panellists).

The results are shown in the following table 6. Questions were performed after 28 days of treatment. Results are expressed as amount of positive responses.

Table 6.

The best acceptance was found among the panellists which were using cream 2a (containing 0.4% of LAE®), followed by the volunteers using cream 2d (with 0.8% of salicylic acid), and finally by the ones using the placebo (cream 2).

Example 4.

Hvdro-alcoholic gels. The active ingredients against acne LAE® and salicylic acid were chosen, at three different concentrations of 0.1 , 0.2 and 0.4% of LAE® and 0.4% and 2.0% of salicylic acid. The compositions which were assessed are displayed in table 7 below.

The suspension test was performed with short times (1 minute and 5 minutes) and 60 minutes.

Table 7.

The results of the corresponding suspension test with P. acnes expressed as log CFU/mL of test solution are shown below in table 8. The detection limit is 2 log CFU/g.

The effect of LAE® is evident even at 0,1% dosage in this formulation. Increasing the amount of LAE® up to 0.4%, results in a better killing of P. acnes at lower times. Salicylic acid is only effective after 1 hour when 2% of the active is employed.

Example 5.

Cosmetic acceptance questionnaire.

Samples 3, 3c and 3e described in example 4 were evaluated by the panel of 18 volunteers with oily and acne-prone skin (each formulation was evaluated by 8 panellists).

Results are shown in the following table 9. Questions were performed after 28 days of treatment. Results are expressed as amount of positive responses.

Table 9.

As can be observed in the questionnaire, the gel 3c (containing 0.4% of LAE) was more accepted than the gel 3 (which was the placebo product) ) and 3e (with 2% of salicylic acid). Industrial application.

The preparations containing LAE® as a typical cationic surfactant display a favourable effect in persons with skin problems such as acne and were well tolerated. Treatment with cationic surfactants may be a favourable alternative to existing treatments.

Claims

CLAIMS:

1. Use of a cationic surfactant derived from the condensation of fatty acids and esterifled dibasic amino acids, according to the following formula (1 ):

where:

X- is Br-, CI-, or HS0₄-, a counter ion derived from an organic or inorganic acids, or an anion on the basis of a phenolic compound;

Ri: is a linear acyl group derived from a saturated fatty acid or hydroxyacid from 8 to 14 atoms of carbon bonded to the a- amino acid group through an amidic bond, R₂: is a linear or branched alkyl chain from 1 to 18 carbon atoms or an aromatic group,

R₃: is

and n can be from 0 to 4,

for the treatment of acne.

2, The use of claim 1 , whereby the cationic surfactant is administered as a topical application.

3. The use of claim 1 or 2, in which the cationic surfactant of the formula (1 ) is the ethyl ester of the lauramide of the arginine monohydrochloride (LAE®).

4. The use according to any of claims 1 to 3, whereby the cationic surfactant is applied as an aqueous solution, an alcoholic solution, a hydroalcoholic solution, or the form of masks, lotions or gels.

5. The use according to any of claims 1 to 4, in which the concentration of the cationic surfactant according to the formula (1 ) :is in the range of 0.0001 wt-% to -5 wt-%, preferably 0.001 wt-% to 1 wt-%, most preferably 0.01 wt-% to 0.9 wt-% and most preferably 0.1 wt-% to 0.8 wt-%.