TITLE: Antimicrobial mixture containing 4-(3-ethoxy-4-hydroxyphenyl)butan-2- one and an ammonium compound, and composition containing same

[0001 ] The present invention relates to an antimicrobial mixture containing 4-

(3-ethoxy-4-hydroxyphenyl)butan-2-one and an ammonium compound, and also to a cosmetic, pharmaceutical or nutritional composition containing such a mixture.

[0002] 4-(3-Ethoxy-4-hydroxyphenyl)butan-2-one (ketone compound) is a beneficial substance as a preserving agent for cosmetic compositions, for protecting the compositions against microbial contamination, as described in patent application WO 2011/039445.

[0003] However, it is desirable to be able to incorporate said ketone compound in reduced concentration in compositions, notably cosmetic or dermatological compositions, while at the same time maintaining good antimicrobial conservation performance. Combinations of the ketone compound with other compounds that have good antimicrobial efficacy are thus sought for this purpose.

[0004] The invention may be better understood on reading the following description accompanied with nonlimiting implementation examples thereof with reference to the appended drawings.

[0005] The inventors have discovered, unexpectedly, that the combination of

4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and salts thereof with an organic or inorganic acid or base, and solvates thereof such as the hydrates; with an ammonium compound especially chosen from cetyltrimethylammonium halide such as cetyltrimethylammonium chloride, bexethonium halide such as bexethonium chloride, and tetradecyltrimethylammonium halide such as tetradecyltrimethylammonium bromide makes it possible to obtain an antimicrobial mixture which has synergistic antimicrobial activity. More over the antimicrobial effect is obtained even without a supplemental antimicrobial agent (i.e. other than 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and ammonium compound) such as salicylic acid.

[0006] The results of the examples described below show the synergistic antimicrobial activity obtained with the minimum inhibitory concentration (MIC) measurements taken with several mixtures. The antimicrobial activity is considered as being synergistic when the antimicrobial mixture makes it possible to obtain a percentage of strain growth of less than or equal to 25%, or even less than or equal to 20%. [0007] The combination of 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and salts thereof with an organic or inorganic acid or base, and solvates thereof such as the hydrates; with cetyltrimethylammonium halide makes it possible to obtain an antimicrobial mixture with synergistic antimicrobial activity, in particular on Gram positive bacteria such as Staphylococcus aureus and Enterococcus faecalis.

[0008] The combination of 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and salts thereof with an organic or inorganic acid or base, and solvates thereof such as the hydrates; with benzethonium chloride makes it possible to obtain an antimicrobial mixture with synergistic antimicrobial activity, in particular on the Gram-positive bacterium Staphylococcus aureus and on yeasts, in particular on Candida albicans.

[0009] The combination of 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and salts thereof with an organic or inorganic acid or base, and solvates thereof such as the hydrates ; with tetradecyltrimethylammonium bromide makes it possible to obtain an antimicrobial mixture with synergistic antimicrobial activity, in particular on molds, notably on Aspergillus niger.

[0010] For the purposes of the present invention, and unless otherwise indicated:

an“anionic counterion" is an anion or an anionic group derived from an organic or mineral acid salt which counterbalances the cationic charge of the ammonium salt; more particularly, the anionic counterion is chosen from: i) halides such as chloride or bromide; ii) nitrates; iii) sulfonates, including C1-C6 alkylsulfonates: Alk-S(0) ₂ 0 such as methanesulfonate or mesylate and ethanesulfonate; iv) arylsulfonates: Ar- S(0)20 such as benzenesulfonate and toluenesulfonate or tosylate; v) citrate; vi) succinate; vii) tartrate; viii) lactate; ix) alkyl sulfates: Alk-0-S(0)0 such as methyl sulfate and ethyl sulfate; x) aryl sulfates: Ar-0-S(0)0 such as benzene sulfate and toluene sulfate; xi) alkoxy sulfates: Alk-0-S(0) ₂ 0 such as methoxy sulfate and ethoxy sulfate; xii) aryloxy sulfates: Ar-0-S(0) ₂ 0 , xiii) phosphates 0=P(0H) ₂ -0\ 0=P(0 )2-0H 0=P(0 )3, H0-[P(0)(0 )] _W -P(0)(0 )2 with w being an integer; xiv) acetate; xv) triflate; and xvi) borates such as tetrafluoroborate, xvii) disulfate (0=) ₂ S(0 ) ₂ or SO4 ² and monosulfate HSCV; preferably anionic counterion is an halide such as Cl or Br,

an " organic or inorganic acid salt' is more particularly chosen from salts chosen from a salt derived from i) hydrochloric acid HCI, ii) hydrobromic acid HBr, iii) sulfuric acid H2SO4, iv) alkylsulfonic acids: Alk-S(0) ₂ 0H such as methanesulfonic acid and ethanesulfonic acid; v) arylsulfonic acids: Ar-S(0) ₂ 0H such as benzenesulfonic acid and toluenesulfonic acid; vi) citric acid; vii) succinic acid; viii) tartaric acid; ix) lactic acid; x) alkoxysulfinic acids: Alk-0-S(0)0H such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H ₃ PO ₄ ; xiii) acetic acid CH ₃ C(0)0H; xiv) triflic acid CF ₃ SO ₃ H; and xv) tetrafluoroboric acid HBF ₄ ;

an“organic or inorganic base salts " means salts of bases or alkaline agents as defined below, such as alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide, or alkaline earth metal calcium hydroxide, ammonia, amines or alkanolamines.

an "alkyl radical' is a linear or branched hydrocarbonyl chain saturated;

moreover, the addition salts that may be used in the context of the invention with 4- (3-ethoxy-4-hydroxyphenyl)butan-2-one are especially chosen from addition salts with a cosmetically acceptable base such as basifying agents as defined below, for instance alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, aqueous ammonia, amines or alkanolamines; preferably 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one can be in a salt form such as formula (G):

Formula (G) in which M ⁺ represents a cationic counter ion especially an alkali metal such as sodium or potassium, or alkaline earth metal such as calcium or ammonium the term "at least one" is equivalent to the term "one or more".

[0011 ] More precisely, a subject of the invention is an antimicrobial mixture comprising, or constituted of (or consisting of)

- at least one 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and salts thereof with an organic or inorganic acid or base, and solvates thereof such as the hydrates; and

- at least one ammonium compound chosen from:

i) an alkyltrimethylammonium salt especially alkyltrimethylammonium halide of formula (I) R-N ⁺ (CH ₃ )3 X-

Formula (I) in which R denotes an alkyl group containing from 12 to 18 carbon atoms, alkyl group can be linear or branched, preferably linear and X- denotes an anionic counter ion preferably halide such as chloride or bromide ion, in particular (I) represents cetyltrimethylammonium halide preferably cetyltrimethylammonium chloride, cetyltrimethylammonium bromide and tetradecyltrimethylammonium halide preferably tetradecyltrimethylammonium bromide; and ii) benzethonium halide especially benzethonium chloride, methylbenzethonium halide especially methylbenzethonium chloride;

being understood that when the mixture comprises salycilic acid and/or 1 ,3- propanediol thus tie alkyltrimethylammonium salt of formula (I) is different from cetyltrimethylammonium chloride.

[0012] Another subject of the invention is a composition, preferably cosmetic, comprising, or constituted of (or consisting of);

- at least one 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and salts thereof with an organic or inorganic acid or base, and solvates thereof such as the hydrates; and

- at least one ammonium compound chosen from:

i) an alkyltrimethylammonium salt especially alkyltrimethylammonium halide of formula (I) R-N ⁺ (CH ₃ )3 X-

Formula (I) in which R denotes an alkyl group containing from 12 to 18 carbon atoms, alkyl group can be linear or branched, preferably linear and X- denotes an anionic counter ion preferably halide such as chloride or bromide ion, in particular (I) represents cetyltrimethylammonium halide preferably cetyltrimethylammonium chloride, cetyltrimethylammonium bromide and tetradecyltrimethylammonium halide preferably tetradecyltrimethylammonium bromide, being understood that the said alkyltrimethylammonium salt of formula (I) is different from cetyltrimethylammonium chloride when the composition comprises salicylic acid and/or 1 ,3-propanediol ; and

ii) benzethonium halide especially benzethonium chloride, methylbenzethonium halide especially methylbenzethonium chloride.

[0013] A subject of the invention is also a composition comprising said antimicrobial mixture described previously.

[0014] According one embodiment of the invention when the mixture contains

4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and an ammonium compound i), thus the said mixture does not comprise a further additional antimicrobial agent.

[0015] According one embodiment of the invention when the mixture contains

4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and an ammonium compound i) and/or ii), thus the said mixture does not comprise a further additional antimicrobial agent.The composition may comprise a physiologically acceptable medium. The composition is notably a cosmetic or pharmaceutical or dermatological composition.

[0016] The composition may optionally be a nutritional composition (food).

[0017] A subject of the invention is also a process for the nontherapeutic cosmetic treatment of keratin materials, comprising the application to the keratin materials of a composition, notably a cosmetic composition, as described previously. The process may be a cosmetic process for caring for or making up or cleansing keratin materials.

[0018] A subject of the invention is also a process for conserving a composition, notably comprising a physiologically acceptable medium, in particular a cosmetic or pharmaceutical composition, or a nutritional composition, characterized in that it consists in incorporating into said composition an antimicrobial mixture as described previously.

[0019] 4-(3-Ethoxy-4-hydroxyphenyl)butan-2-one is a compound of formula:

[0020] and salts thereof with an organic or inorganic acid or base, and solvates thereof such as the hydrates.According to a first embodiment, a Subject of the invention is an antimicrobial mixture comprising, or constituted of (or consisting of), 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and an alkyltrimethylammonium salt especially alkyltrimethylammonium halide preferably alkyltrimethylammonium chloride of formula (la).

R-N ⁺ (CH ₃ ) ₃ Cl (la) in which R denotes an alkyl group containing from 12 to 18 carbon atoms, alkyl group can be linear or branched, preferably linear.

[0021 ] According one embodiment of the invention the ammonium compound

(I) may be chosen from cetyltrimethylammonium halide such as cetyltrimethylammonium chloride, lauryltrimethylammonium halide, stearyltrimethylammonium halide, and preferably cetyltrimethylammonium halide, and tetradecyltrimethylammonium halide.

[0022] The ammonium compound (la) may be chosen from cetyltrimethylammonium chloride, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, and preferably cetyltrimethylammonium chloride.

[0023] Advantageously, 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and the ammonium compound (I), preferably cetyltrimethylammonium halide, are present in said mixture in a content such that the 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one/ and the ammonium compound (I), in particular cetyltrimethylammonium halide weight ratio ranges from 1500 to 10 000, preferably from 1800 to 10 000, preferentially from 3000 to 6000, more preferentially from 3600 to 4400. Such a mixture has good antimicrobial activity on the bacterium Staphylococcus aureus

[0024] More advantageously, 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and the ammonium compound (la), preferablycetyltrimethylamrnonium chloride, are present in said mixture in a content such that the 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one/ and the ammonium compound (la), in particular cetyltrimethylammonium chloride weight ratio ranges from 1500 to 10 000, preferably from 1800 to 10 000, preferentially from 3000 to 6000, more preferentially from 3600 to 4400. Such a mixture has good antimicrobial activity on the bacterium Staphylococcus aureus.

[0025] The antimicrobial mixture may have a 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one/[ammonium compound (I), preferably cetyltrimethylammonium halide] weight ratio ranging from 1800 to 8500, preferably ranging from 1800 to 5000, preferably ranging from 1800 to 4000, preferably ranging from 1900 to 3000. Such a mixture has good antimicrobial activity on the bacterium Enterococcus faecalis.

[0026] The antimicrobial mixture may have a 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one/[ammonium compound (la), preferablycetyltrimethylammonium chloride] weight ratio ranging from 1800 to 8500, preferably ranging from 1800 to 5000, preferably ranging from 1800 to 4000, preferably ranging from 1900 to 3000. Such a mixture has good antimicrobial activity on the bacterium Enterococcus faecalis.

[0027] Preferably, the composition comprises 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one in a content ranging from 0.08 % to 0.4 % by weight, preferentially ranging from 0.1 % to 0.4 % by weight and better still ranging from 0.15 % to 0.4 % by weight, and even better still ranging from 0.2 % to 0.3 % by weight, relative to the total weight of the composition.

[0028] Preferably, the composition comprising the antimicrobial mixture may comprise 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one in a content ranging from 0.08% to 0.4% by weight, preferentially ranging from 0.1 % to 0.4% by weight and better still ranging from 0.15% to 0.4% by weight, and even better still ranging from 0.2 to 0.3% by weight, relative to the total weight of the composition.

[0029] Preferably, the composition comprising the antimicrobial mixture comprise the ammonium compound (I), in particular cetyltrimethylammonium halide, in a content ranging from 0.000025 % to 0.00008 % by weight relative to the total weight of the composition, preferentially ranging from 0.00004 % to 0.00008 % by weight. [0030] Preferably, the composition comprising the antimicrobial mixture comprise the ammonium compound (la), in particular cetyltrimethylammonium chloride, in a content ranging from 0.000025% to 0.00008% by weight relative to the total weight of the composition, preferentially ranging from 0.00004% to 0.00008% by weight.

[0031 ] According to another embodiment, a subject of the invention is an antimicrobial mixture comprising, or constituted of (or consisting of), 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one and a benzethonium compound chosen from benzethonium halide and methylbenzethonium halide, preferably benzethonium halide.

[0032] According to a another embodiment, a subject of the invention is an antimicrobial mixture comprising, or constituted of (or consisting of), 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one and a benzethonium compound chosen from benzethonium chloride and methylbenzethonium chloride, preferably benzethonium chloride.

[0033] The antimicrobial mixture may have a 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one/[benzethonium compound (preferably benzethonium halide and more preferably benzethonium chloride)] weight ratio ranging from 4 to 1200, preferably ranging from 4 to 1000, preferentially ranging from 4 to 875 and more preferentially ranging from 4 to 600.

[0034] The antimicrobial mixture may have a 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one/[benzethonium compound (preferably benzethonium halide and more preferably benzethonium chloride)] weight ratio ranging from 15 to 1200, preferably ranging from 30 to 1200, preferably ranging from 15 to 1000, preferably ranging from 30 to 1000, preferably ranging from 15 to 875, preferably ranging from 30 to 875, preferably ranging from 15 to 600, preferably ranging from 30 to 600. Such a mixture has good antimicrobial activity on the Gram-positive bacterium Staphylococcus aureus.

[0035] Preferably, the composition comprising the antimicrobial mixture may comprise 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one in a content ranging from 0.05 % to 0.9 % by weight, relative to the total weight of the composition, preferably ranging from 0.005 % to 0.7 % by weight, preferably ranging from 0.1 % to 0.9 % by weight, preferably ranging from 0.15 % to 0.9 % by weight, preferably ranging from 0.2 % to 0.9 % by weight, preferably ranging from 0.3 % to 0.9 % by weight, preferably ranging from 0.4 % to 0.8 % by weight, preferably ranging from 0.4 % to 0.7 % by weight.

[0036] Preferably, the composition comprising the antimicrobial mixture may comprise the benzethonium compound, in particular benzethonium halide and more preferably benzethonium chloride, in a content ranging from 0.0008% to 0.003% by weight relative to the total weight of the composition, preferentially ranging from 0.0008% to 0.0015% by weight.

[0037] The antimicrobial mixture may have a 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one/[benzethonium compound (preferably halide and more preferably benzethonium chloride)] weight ratio ranging from 4 to 140, preferably ranging from 4 to 100, preferentially ranging from 4 to 60, more preferentially ranging from 4 to 50, better still ranging from 4 to 30 and even better still ranging from 10 to 30. Such a mixture has good antimicrobial activity on the yeast Candida albicans.

[0038] Preferably, the composition comprising the antimicrobial mixture may comprise 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one in a content ranging from 0.02% to 0.18% by weight, relative to the total weight of the composition, preferably ranging from 0.02% to 0.15% by weight, preferably ranging from 0.02% to 0.08% by weight, preferably ranging from 0.02% to 0.04% by weight.

[0039] Preferably, the composition comprising the antimicrobial mixture may comprise the benzethonium compound, in particular benzethonium halide and more preferably benzethonium chloride, in a content ranging from 0.001 % to 0.008% by weight, relative to the total weight of the composition, preferentially ranging from 0.001 % to 0.006% by weight, more preferentially ranging from 0.001 % to 0.004% by weight, better still ranging from 0.001 % to 0.003% by weight, better still ranging from 0.001 % to 0.002% by weight and even better still ranging from 0.001 % to 0.0018% by weight.

[0040] According to another embodiment, a subject of the invention is an antimicrobial mixture comprising, or constituted of (or consisting of), 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one and an alkyltrimethylammonium bromide of formula (lb)

R-N ⁺ (CH ₃ ) ₃ Br (lb) in which R denotes an alkyl group containing from 12 to 18 carbon atoms, alkyl group can be linear or branched, preferably linear.

[0041 ] The ammonium compound (lb) may be chosen from cetyltrimethylammonium bromide, lauryltrimethylammonium bromide, stearyltrimethylammonium bromide, and preferably tetradecyltrimethylammonium bromide.

[0042] Advantageously, 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one and the ammonium compound (lb), in particular tetradecyltrimethylammonium bromide, are present in said mixture in a content such that the 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one/[ammonium compound (lb), in particular tetradecyltrimethylammonium bromide] weight ratio ranges from 0.3 to 9, preferably from 0.5 to 9, preferably from 0.3 to 7, preferably from 0.5 to 7, preferably from 0.3 to 6, preferably from 0.5 to 6, preferably from 0.3 to 3.5, preferably from 0.5 to 3.5. Such a mixture has good antimicrobial activity on molds, notably on Aspergillus niger.

[0043] Preferably, the composition comprising the antimicrobial mixture may comprise 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one in a content ranging from 0.015% to 0.09% by weight, relative to the total weight of the composition, preferably ranging from 0.015% to 0.08% by weight, preferably ranging from 0.02% to 0.07% by weight, preferably ranging from 0.02% to 0.06% by weight, preferably ranging from 0.02% to 0.035% by weight.

[0044] Preferably, the composition comprising the antimicrobial mixture may comprise the ammonium compound (lb), in particular tetradecyltrimethylammonium bromide, in a content ranging from 0.01 % to 0.04% by weight, relative to the total weight of the composition, preferentially ranging from 0.01 % to 0.03% by weight, more preferentially ranging from 0.01 % to 0.02% by weight.

[0045] A subject of the invention is also a composition comprising, in a physiologically acceptable medium, the antimicrobial mixture described previously.

[0046] The term "physiologically acceptable medium" means a medium that is compatible with human keratin materials such as the skin, the scalp, the hair and the nails. Said medium may comprise one or more additional ingredients other than the ketone compound and the ammonium compound.

[0047] The compound 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one may be present in the composition according to the invention in a content ranging from 0.01 % to 5% by weight, relative to the total weight of the composition, preferably ranging from 0.01 % to 3% by weight, preferentially ranging from 0.01 % to 2.5% by weight, more preferentially ranging from 0.01 % to 2% by weight and better still ranging from 0.015% to 0.9% by weight, or else in the contents described previously.

[0048] The composition may comprise at least one additional ingredient chosen from water, oils, polyols containing from 2 to 10 carbon atoms, gelling agents, surfactants, film-forming polymers, dyestuffs, fragrances, fillers, UV- screening agents, plant extracts, cosmetic and dermatological active agents, and salts.

[0049] The composition according to the invention may comprise an aqueous phase.

[0050] The composition may also comprise a polyol that is water-miscible at room temperature (25 °C), notably chosen from polyols notably containing from 2 to 10 carbon atoms, preferably containing from 2 to 6 carbon atoms, such as glycerol, propylene glycol, 1 ,3-propanediol, butylene glycol, pentylene glycol, hexylene glycol, dipropylene glycol, diethylene glycol or diglycerol. Advantageously, the composition according to the invention comprises 1 ,3-propanediol, notably in a content ranging from 0.1 % to 20 % by weight, preferably ranging from 0.1 % to 10 % by weight and preferentially ranging from 0.5 % to 5 % by weight, relative to the total weight of the composition.

[0051 ] The compositions according to the invention may be in the form of oil- in-water (O/W) emulsions, water-in-oil (W/O) emulsions or multiple emulsions (triple: W/O/W or O/W/O), oily solutions, oily gels, aqueous solutions, aqueous gels, or solid compositions. These compositions are prepared according to the usual methods.

[0052] The compositions according to the invention may be more or less fluid and may have the appearance of a white or coloured cream, an ointment, a milk, a lotion, a serum, a paste or a foam. They may be optionally applied to the skin in aerosol form. They may also be in solid form, for example in the form of a stick or a compact powder.

[0053] The composition according to the invention may notably be in the form of:

- a makeup product, notably for making up the skin of the face, the body, or the lips or the eyelashes;

- an aftershave gel or lotion; a shaving product;

- a deodorant (stick, roll-on or aerosol);

- a hair-removing cream;

- a body hygiene composition such as a shower gel or a shampoo;

- a pharmaceutical composition;

- a solid composition such as a soap or a cleansing bar;

- an aerosol composition also comprising a pressurized propellant;

- a hair-setting lotion, a hair-styling cream or gel, a dyeing composition, a permanent-waving composition, a lotion or a gel for combating hair loss, or a hair conditioner;

- a composition for caring for or cleansing the skin.

[0054] A subject of the invention is also a process for preparing a composition, notably a cosmetic or pharmaceutical or nutritional composition, comprising a step of mixing 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one, the ammonium compound described previously and one or more additional ingredients, notably cosmetic or pharmaceutical or nutritional ingredients, such as those described previously.

[0055] The antimicrobial mixtures of the three embodiments described previously may be used for preserving foodstuffs (food).

[0056] A subject of the invention is also a nutritional composition comprising an antimicrobial mixture chosen from those described previously. [0057] The nutritional composition (food) may comprise at least one foodstuff chosen from meats, fish, crustaceans, vegetables, fruit, cereals, eggs, butter, milk, vinegar, water, vegetable oils, sugars, salt, spices, emulsifiers, alcohols, thickeners and honey.

[0058] Preferably the 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one is predissolved in a food-grade solvent before being added to the food. Solvents that may be used include ethanol, propylene glycol, isopropyl alcohol and mixtures thereof, optionally combined with water.

[0059] The food according to the invention may be, for example, in the form of bread, cake, sauce, candy, a cooked dish, confectionery, jelly, dessert, nougat, drinks, juice, syrup, wine, beer, ravioli, mousse, compote, mayonnaise, mustard, vinaigrette, crisps, sausage, gnocchi, polenta, pancakes, pates, cheeses, flour, delicatessen meats or soup.

[0060] The 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one may be present in the food composition in the concentrations described previously.

[0061 ] The synergistic activity of the antimicrobial mixture according to the invention on fungi, in particular on the species Candida albicans, is also of interest in water treatment. Specifically, fungi represent one of the sources of contamination of water as mentioned in the article “Fungal Contaminants in drinking water regulation? A tale of ecology, exposure, purification and clinical relevance " Int. J. Environ. Res. Public Health 2017, 14, 636.

[0062] The synergistic activity of the antimicrobial mixture according to the invention on Gram-positive bacteria, in particular on bacteria of the species Enterococcus faecalis is also of interest in water treatment. Specifically, bacteria of the genus Enterococcus represent one of the sources of contamination of water as mentioned in the article“Enterococci, from commensals to leading causes of drug resistant infection” Michael S. Gilmore et al., 2014, Massachusetts Eye and Ear Infirmary, Boston.

[0063] The antimicrobial mixtures of the first and second embodiments described previously may be used for water treatment.

[0064] The present invention also relates to the use of the antimicrobial mixture chosen from those of the first and second embodiments described previously in water treatment, in which said water is chosen from domestic or industrial waters, waters from aquatic media, swimming pool/spa waters, and waters from air-conditioning systems.

[0065] The term "water treatment" refers to a continuous or discontinuous

(batch-type) treatment which consists in adding a substance to a water sample to be treated or to a water stream to be treated for the purpose either of preventing the contamination of the water with a contaminant or of partially or totally decontaminating of said contaminant said water to be treated

[0066] Preferably, the water treatment performed in the context of the present invention consists in continuously or discontinuously adding a substance to a sample of water to be treated or to a water stream to be treated in order to partially or totally decontaminate of a contaminant said water to be treated.

[0067] The contaminant may be a microorganism, in particular a bacterium and/or a fungus.

[0068] Even more preferentially, said water treatment is a treatment of water contaminated with one or more microorganisms, preferably with Gram-positive or Gram-negative bacteria or fungi of the species Enterococcus faecalis or Candida albicans.

[0069] For the purposes of the present invention, the "domestic or industrial waters" comprise spent waters before they have been treated in a purification plant, waters undergoing treatment in a purification plant, waters before they have been treated in a drinking water plant, waters undergoing treatment in a drinking water plant, and also waters circulating in potable or non-potable urban networks, for instance waters circulating in pipeworks.

[0070] The present invention also relates to a continuous or discontinuous water treatment process comprising at least one step of placing a water sample to be treated or a water stream to be treated, said water to be treated being chosen from domestic or industrial waters, waters from aquatic media, swimming pool/spa waters, and waters from air-conditioning systems, in contact with the antimicrobial mixture according to the invention.

[0071 ] Preferably, said step of placing the water to be treated in contact with the antimicrobial mixture according to the invention may notably be performed by injection in liquid form of said compound, by passage through a filter or a filtering cartridge comprising said compound, or by administration in solid form of said compound notably in the form of granules, lozenges or pellets.

[0072] The 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one may be used in a proportion of at least 0.02% by weight, preferably of at least 0.06% by weight, preferably at least 0.1 % by weight and better still at least 0.5% by weight relative to the total weight of water to be treated. In a preferred embodiment, the compounds of formula (I), alone or as a mixture, may be used in a proportion of at least 1 % by weight relative to the total weight of water to be treated.

[0073] The 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one may be used in a concentration ranging from 0.02% to 10% by weight, preferably from 0.02% to 5% by weight and better still from 0.02% to 2% by weight relative to the total weight of water to be treated. In a preferred embodiment, the 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one may be used in a concentration ranging from 0.02% to 1 % by weight relative to the total weight of water to be treated, and better still from 0.02% to 0.4% by weight, or else according to the contents described previously.

[0074] In a preferred embodiment, the 4-(3-ethoxy-4- hydroxyphenyl)butan-2-one is used in combination with an effective amount of at least one organic solvent which may be chosen from ethanol, 1 ,2-propylene glycol, 1 ,3-propanediol, PEG-8 (polyethylene glycol containing 8 ethylene glycol units), propylene carbonate, dipropylene glycol, 1 ,2-hexylene glycol, PEG-4.

[0075] Preferably, the organic solvent is chosen from ethanol, 1 ,2-propylene glycol, 1 ,3-propanediol, PEG-8 and propylene carbonate.

[0076] The solvent may be used in a content ranging from 0.05 % to 10 % by weight relative to the total weight of the water to be treated, preferably ranging from 0.1 % to 5 % by weight and preferentially ranging from 0.1 % to 2.5 % by weight relative to the total weight of the water to be treated.

[0077] The invention is illustrated in greater detail in the example that follows.

The amounts of the ingredients are expressed as weight percentages.

Examples

[0078] Example 1 : Determination of the synergistic antimicrobial activity as MIC

[0079] The demonstration of a synergistic antimicrobial activity effect with a mixture of 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one (referred to as substance A) and of an ammonium compound (referred to as substance B) was performed by calculating the synergy index (or FIC index) according to the following formula:

[0080] [Math. 1 ]

FIC Index = ( MIC of A with B / MIC of A ) + ( IC of B with A / MIC of B ) with:

- MIC of A with B: minimum concentration of product A in the combination A + B which makes it possible to obtain an inhibitory effect;

- MIC of B with A: minimum concentration of product B in the combination A + B which makes it possible to obtain an inhibitory effect;

- MIC of A: minimum inhibitory concentration of product A alone;

- MIC of B: minimum inhibitory concentration of product B alone.

This formula was described for the first time in the article by F.C. Kull, P.C. Eisman, H. D. Sylwestrowka, and R.L. Mayer, Applied Microbiology 9:538-541 , 1961. [0081 ] For each compound tested alone, the MIC is considered as the first concentration which makes it possible to obtain a microbial growth percentage of less than or equal to 25%.

[0082] As regards the combinations tested, MIC of A with B and MIC of B with

A are the respective concentrations of A and of B in the combinations which make it possible to obtain a microbial growth percentage of less than or equal to 25%.

[0083] Interpretation of the FIC Index:

[0084] When the FIC index value is less than or equal to 1 , it is considered that the combination of test compounds has a synergistic effect.

[0085] The summary of the results obtained is presented in the following tables.

[0086] The combination of compounds A and B was tested on the following strains or a part thereof: Aspergillus niger, Staphylococcus aureus, Enterococcus faecalis, Candida albicans.

[0087] The microbial strain Aspergillus niger ATCC 6275, and a double concentration Sabouraud broth liquid culture medium supplemented with polyoxyethylenated (20 OE) sorbitan monopalm itate (Tween 40 from Croda) and Phytagel© BioReagent were used (i.e. a mixture of 5 g of Phytagel + 0.6 g of Tween 40 + 60 g of Sabouraud broth).

[0088] The microbial strain Staphylococcus aureus ATCC 6538 and a double concentration nutrient broth liquid culture medium were used.

[0089] The microbial strain Enterococcus faecalis ATCC 33186 and a double concentration BHI (Brain Fleart Infusion) broth liquid culture medium were used.

[0090] The microbial strain Candida albicans ATCC 10231 , and a double concentration Sabouraud broth liquid culture medium were used (i.e. a mixture of 5 g of Phytagel + 0.6 g Tween 40 + 60 g of Sabouraud broth).

[0091 ] A 96-well microplate at an incubation temperature of 32.5°C is used.

[0092] The incubation time of the microplate is:

- from 24 to 30 h under aerobic conditions for microbial Aspergillus niger ATCC 6275;

- from 18 to 24 h under aerobic conditions for Candida albicans ATCC 10231 , and Staphylococcus aureus ATCC 6538;

- from 24 to 48 h under aerobic conditions for Enterococcus faecalis ATCC 33186.

[0093] Tests

[0094] For each compound: [0095] A = 4-(3-ethoxy-4-hydroxyphenyl) butan-2-one compound

[0096] B = ammonium salt

[0097] A 10% (weight/volume) stock solution was prepared by mixing 1 g of compound in 9 ml of aqueous 1 %o agar solution. Successive dilutions were made with the 1 %o agar solution.

[0098] Tests of compounds A and B alone

[0099] 50 pi of each of the daughter solutions obtained containing compound

A or B are added to the microplate wells. 100 mI of Sabouraud liquid nutrient broth inoculated at double concentration with the Aspergillus niger strain and 50 mI of aqueous 1 %o agar solution are also added thereto.

[00100] Tests of compounds A and B as a mixture

[00101 ] 50 mI of each of the daughter solutions obtained containing compound

A and 50 mI of each of the daughter solutions obtained containing compound B are added to the microplate wells. 100 mI of Sabouraud liquid nutrient broth inoculated at double concentration with the strain Aspergillus niger are also added thereto.

[00102] Microbial growth control

[00103] A positive microbial growth control was also prepared. The positive microbial growth control corresponds to a mixture of 100 mI of aqueous 1%o agar solution with 100 mI of Sabouraud liquid nutrient broth inoculated at double concentration with the strain Aspergillus niger in the absence of compounds A and B.

[00104] Absorbance control for compounds A and B alone

[00105] An absorbance control was performed in parallel on compounds A and

B alone. This control corresponds to 100 mI of double concentration sterile Sabouraud liquid nutrient broth + 100 mI of double concentration compound A or B.

[00106] In the three cases (absorbance control, growth control and test), the final volume present in each of the microplate wells is 200 mI.

[00107] In the two cases (test and control), the inoculum represents the concentration of the Aspergillus niger strain present in the final volume of the wells (200 mI) and is between 2 and 6x10 ⁵ cfu/ml of Aspergillus niger.

[00108] The minimum inhibitory concentration (MIC) of each compound A and

B alone and in combination was determined in a known manner by means of optical density measurements at a wavelength of 620 nm.

[00109] The test as described above (tests, absorbance control and growth control) was performed again to test the combination A + B on the following strains Enterococcus faecalis, Staphylococcus aureus, Candida albicans, where appropriate.

[00110] The following results were obtained with compound B1 = cetyltrimethylammonium chloride (as an aqueous solution at 25% by weight):

[00111 ] Enterococcus faecalis

[00112] [Tables 1 ]

[00113] [Tables 2]

[00114] The results obtained show synergistic inhibitory activity for the mixtures:

i) 0.125% of A and 0.00006% of B1 , i.e. ratio A/B1 = 2083

ii) 0.25% of A and 0.00006% of B1 , i.e. ratio A/B1 = 4166

iii) 0.25% of A and 0.00003% of B1 , i.e. ratio A/B1 = 8333

[00115] Staphylococcus aureus

[00116] [Tables 3]

[00117] [Tables 4]

[00118] The results obtained show synergistic inhibitory activity for the mixtures:

i) 0.125% of A and 0.00006% of B1 , i.e. ratio A/B1 = 2083 ii) 0.25% of A and 0.00006% of B1 , i.e. ratio A/B1 = 4166

iii) 0.25% of A and 0.00003% of B1 , i.e. ratio A/B1 = 8333

[00119] Example 2:

[00120] The demonstration of a synergistic antimicrobial activity effect with a mixture of 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one (referred to as substance A) and of benzethonium chloride (referred to as substance B2) was performed according to the conditions described in Example 1.

[00121 ] The following results were obtained:

[00122] Staphylococcus aureus

[00123] [Tables 5]

[00124] [Tables 6]

[00125] The results obtained show synergistic inhibitory activity for the mixtures:

i) 0.5% of A and 0.001 % of B2, i.e. ratio A/B2 = 500 ii) 0.25% of A and 0.001 % of B2, i.e. ratio A/B2 = 250 iii) 0.125% of A and 0.001 % of B2, i.e. ratio A/B2 = 125 iv) 0.0625% of A and 0.001 % of B2, i.e. ratio A/B2 = 62 v) 0.5% of A and 0.002% of B2, i.e. ratio A/B2 = 250 vi) 0.25% of A and 0.002% of B2, i.e. ratio A/B2 = 125 vii) 0.125% of A and 0.002% of B2, i.e. ratio A/B2 = 62 viii) 0.0625% of A and 0.002% of B2, i.e. ratio A/B2 = 31

Candida albicans

[00126] [Tables 7]

[00127] [Tables 8]

[00128] The results obtained show synergistic inhibitory activity for the mixtures:

i) 0.1 % of A and 0.005% of B2, i.e. ratio A/B2 = 20 ii) 0.05% of A and 0.005% of B2, i.e. ratio A/B2 = 10 iii) 0.025% of A and 0.005% of B2, i.e. ratio A/B2 = 5

iv) 0.1 % of A and 0.0025% of B2, i.e. ratio A/B2 = 40 v) 0.05% of A and 0.0025% of B2, i.e. ratio A/B2 = 20 vi) 0.025% of A and 0.0025% of B2, i.e. ratio A/B2 = 10 vii) 0.1 % of A and 0.00125% of B2, i.e. ratio A/B2 = 80 viii) 0.05% of A and 0.00125% of B2, i.e. ratio A/B2 = 40

ix) 0.025% of A and 0.00125% of B2, i.e. ratio A/B2 = 20

[00129] Example 3:

[00130] The demonstration of a synergistic antimicrobial activity effect with a mixture of 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one (referred to as substance A) and of tetradecyltrimethylammonium bromide (referred to as substance B3) was performed according to the conditions described in Example 1 .

[00131 ] Aspergillus niger

[00132] [Tables 9]

[00133] [Tables 10]

[00134] The results obtained show synergistic inhibitory activity for the mixtures:

i) 0.05% of A and 0.025% of B3, i.e. ratio A/B3 = 2

ii) 0.025% of A and 0.025% of B3, i.e. ratio A/B3 = 1

iii) 0.05% of A and 0.0125% of B3, i.e. ratio A/B3 = 4 iv) 0.025% of A and 0.0125% of B3, i.e. ratio A/B3 = 2.