Patent Application
20150208649
The present invention relates to compositions comprising p-hydroxybenzylamine or a salt thereof and at least one preservative as well as to the use of p-hydroxybenzylamine or a salt thereof to boost the antimicrobial activity of at least one preservative.
To protect cosmetics against mold and bacteria, most cosmetic products currently on the market contain preservatives. While these preservatives protect against bacteria and fungi, studies have linked daily exposure to many of these substances to an increased risk of skin irritation, cancer and/or endocrine problems. Thus, many cosmetic manufactures are searching for alternatives which allow reducing the amount of preservatives and don't appear to pose any health risks.
Surprisingly, it has been found that p-hydroxybenzylamine synergistically increases the antimicrobial activity of preservatives conventionally used in cosmetic applications thus allowing the reduction of the amount of preservatives used when formulating cosmetic compositions.
Thus, the present invention provides a composition comprising of p-hydroxybenzylamine or a salt thereof and at least one preservative. Such compositions show an enhanced antimicrobial activity such as in particular an enhanced anti-fungal and anti-bacterial efficiency.
In another embodiment, the invention relates to the use of p-hydroxybenzylamine or a salt thereof for increasing the antimicrobial activity of at least one preservative.
In a further embodiment the invention relates to a method of increasing the antimicrobial activity of at least one preservative, said method comprising the addition of p-hydroxybenzylamine or a salt thereof into a topical composition and observing or appreciating the result.
In addition, the invention relates to a method for killing and/or inhibiting growth of microbial cells, in particular fungal and/or bacterial cells, said method comprising contacting said microbial cells with a mixture consisting of p-hydroxybenzylamine or a salt thereof and at least one preservative.
The ratio of p-hydroxybenzylamine or a salt thereof to the at least one preservative in the compositions according to the present invention depends on the preservative(s) used and can easily be determined by a person skilled in the art and is illustrated in the examples. Preferably an excess (in weight) of p-hydroxybenzylamine or a salt thereof is used, i.e. the ratio (w/w) of p-hydroxybenzylamine or a salt thereof to the total amount of preservative(s) is >1. In all embodiments according to the present invention preferably the ratio (w/w) of p-hydroxybenzylamine or a salt thereof to the (total) amount of preservative(s) is selected in the range of 2:1 to 100:1 such as in the range of 3:1 to 50:1.
The p-hydroxybenzylamine or a salt thereof and the preservative may be incorporated into the compositions according to the present invention either in the form of a pre-mix or may be added separately.
The amount of p-hydroxybenzylamine or a salt thereof in the compositions according to the present invention may easily be adapted by a person skilled in the art. Preferably in all embodiments according to the invention p-hydroxybenzylamine or a salt thereof is used in an amount of at least 0.0001 wt.-%. More preferably, p-hydroxybenzylamine or a salt thereof is used in an amount of about 0.001 to 10 wt.-%, in particular in an amount of about 0.005 wt.-% to 5 wt.-% such as in an amount of about 0.01 to 1 wt.-%, based on the total weight of the composition.
The total amount of preservative(s) in the compositions according to the present invention is not critical and can easily be adjusted by a person skilled in the art. Advantageously the (total) amount of the at least one preservative in the compositions according to the present invention is selected in the range of 0.001 to 5 wt.-% such as in particular in the range of 0.0.01 to 1 wt.-% such as most in particular in the range of 0.01 to 0.5 wt.-%, based on the total weight of the composition.
The term “antimicrobial activity” (or “antimicrobial effect”) as used herein means a capability of killing and/or inhibiting growth of microbial cells such as in particular bacteria and fungi.
The term “preservative” as used herein refers to compounds having an antimicrobial activity and which are conventionally used in topical (cosmetic) compositions to inhibit decomposition by microbial growth. A list of suitable preservatives can e.g. be found in CTFA Cosmetic Ingredient handbook, First edition 1988 page 78, SPC November 2008: 79-85 (Preservative regulations: a global overview) or Cosmetics & Toiletries Magazine 121(7):65-66, 2006.
Particularly suitable preservatives to be used according to the present invention are parabenes, isothiazolinone-derived biocides or phenoxyethanol as well as mixtures thereof.
p-Hydroxybenzylamine is also known as 4-hydroxybenzylamine respectively 4-(aminomethyl)-phenol [CAS 696-60-6] and is e.g. commercially available at Ugarit Chimie (Issy les Moulineux, France).
According to the present invention p-hydroxybenzylamine can also be employed in the form of a salt thereof. Suitable salts encompass e.g. salts obtainable with acids, such as e.g. with mineral acids such as hydrogen chloride, hydrogen bromide, sulphuric acid or phosphoric acid; with appropriate carboxylic acids, e.g. aliphatic mono- or dicarboxylic acids such as formic acid, acetic acid, trifluoroacetic acid, trichloroacetic acid, propionic acid, glycolic acid, succinic acid, fumaric acid, malonic acid, maleic acid, oxalic acid, phthalic acid, citric acid, lactic acid or tartaric acid; with aromatic carboxylic acids such as benzoic acid or salicylic acid; with aromatic-aliphatic carboxylic acids such as mandelic acid or cinnamic acid; with heteroaromatic carboxylic acids such as nicotinic acid; or with aliphatic or aromatic sulfonic acids such as methanesulfonic acid or toluenesulfonic acid. Particular suitable salts of p-hydroxybenzylamine for the purpose of the present invention are the hydrochloride [CAS 1004-23-5] or the hydrobromide [CAS 90430-14-1].
Preferably, in all embodiments of the present invention p-hydroxybenzylamine is used in the form of its hydrochloride. Nevertheless, even if incorporated as free amine, the actual form of p-hydroxybenzylamine in the compositions according to the present invention, i.e. its existence as free amine or a salt thereof may depend on the respective pH/mixture of a specific composition.
The term “paraben” as used herein refers to esters of para-hydroxybenzoic acid. Common parabens include methylparaben [CAS No. 99-76-3], ethylparaben [CAS No. 120-47-8], propylparaben [CAS No 94-13-3], butylparaben [CAS No. 94-26-8], heptylparaben [CAS1085-12-7], isobutylparaben [CAS No. 4247-02-3], isopropylparaben [CAS No. 4191-73-5] and benzylparaben [CAS No. 94-18-8] as well as salts thereof such as in particular sodium salts.
Particular suitable parabens according to the present invention are methylparaben, ethylparaben, butylparaben, isopropylparaben and/or propylparaben. These parabens are e.g. commercially available as Nipagin M, Nipagin A and Nipasol M or as a mixture of parabens with phenoxyethanol as Phenonip (phenoxyethanol, methylparaben, ethylparaben, butylparaben, propylparaben, isobutylparaben) at Clariant UK Ltd. Preferably, in all embodiments of the invention the methylparaben is used in an amount ranging from 0.1 to 0.3 wt.-% and the ethyl- and propylparaben, independently of each other, are used in an amount of 0.02 to 0.1 wt.-%, based on the total weight of the composition.
Exemplary isothiazoline derived biocides according to the present invention are 5-chloro-2-methyl-4-isothiazolin-3-one (chloromethylisothiazolinone or CMIT) and 2-methyl-4-isothiazolin-3-one (methylisothiazolinone or MIT) which are the active ingredients in a 3:1 mixture (CMIT:MIT) sold commercially as Kathon™. In all embodiments of the invention the isothiazoline derived biocides are preferably used in an amount selected in the range of 0.001 to 0.05 wt.-% such as in particular in an amount selected in the range of 0.005 to 0.01 wt.-%, based on the total weight of the composition.
In all embodiments of the invention preferably the at least one preservative is selected from the group consisting of methylparaben, methylisothiazoline and phenoxyethanol as well as mixtures thereof. Even more preferably, in all embodiments of the present invention only methylparaben, methylisothiazoline and phenoxyethanol or mixtures thereof are used as preservatives.
In a particular embodiment, the compositions according to the present invention are topical compositions. The term “topical composition” as used herein refers in particular to cosmetic compositions that can be topically applied to mammalian keratinous tissue such as e.g. human skin or scalp.
The term “cosmetic composition” as used in the present application refers to cosmetic compositions as defined under the heading “Kosmetika” in Römpp Lexikon Chemie, 10th edition 1997, Georg Thieme Verlag Stuttgart, New York as well as to cosmetic compositions as disclosed in A. Domsch, “Cosmetic Compositions”, Verlag für chemische Industrie (ed. H. Ziolkowsky), 4th edition, 1992.
As the topical compositions according to the present invention further comprise a physiologically acceptable medium, that is to say a medium compatible with keratinous substances, such as the skin, mucous membranes, and keratinous fibres. In particular the physiologically acceptable medium is a cosmetically acceptable carrier.
The term cosmetically acceptable carrier refers to all carriers and/or excipients and/or diluents conventionally used in cosmetic compositions.
Preferred topical compositions according to the invention are topical compositions further comprising a cosmetically acceptable carrier. In particular the topical compositions are skin care preparations, hair care preparations, decorative preparations, and functional preparations such as particularly skin and hair care preparations.
Examples of skin care preparations are, in particular, light protective preparations, anti-ageing preparations, preparations for the treatment of photo-ageing, body oils, body lotions, body gels, treatment creams, skin protection ointments, skin powders, moisturizing preparations such as moisturizing gels, moisturizing sprays, face and/or body moisturizers, skin-tanning preparations (i.e. compositions for the artificial/sunless tanning and/or browning of human skin), for example self-tanning creams as well as skin lightening preparations.
Examples for hair care preparations are hair-washing preparations in the form of shampoos, hair conditioners, hair-care preparations such as e.g. pretreatment preparations, hair tonics, styling creams, gels such as styling gels, pomades, hair rinses, treatment packs, intensive hair treatments, hair-straightening preparations, liquid hair-setting preparations, hair foams (hair mousses) and hairsprays.
Examples of decorative preparations are, in particular, lipsticks, eye shadows, mascaras, dry and moist make-up formulations, rouges and/or powders.
Examples of functional preparations are cosmetic or pharmaceutical compositions containing active ingredients such as hormone preparations, vitamin preparations, vegetable extract preparations, anti-ageing preparations, moisturizing preparations and/or antimicrobial (antibacterial or antifungal) preparations without being limited thereto.
In a particular embodiment the topical compositions according to the invention are skin care preparations or hair care preparations.
The topical compositions according to the present invention are particular suitable for the treatment of skin and/or scalp barrier abnormalities such as xerotic skin conditions, pruritus, itching, sensitive skin and dandruff as well as inflammatory skin and/or scalp disorders and symptoms associated therewith.
Preferably, the topical compositions according to the invention are in the form of a suspension or dispersion in solvents or fatty substances, or alternatively in the form of an emulsion or micro emulsion (in particular of O/W- or W/O-type), PIT-emulsion, nano emulsion, multiple emulsion (e. g. O/W/O- or W/O/W-type), pickering emulsion, hydrogel, alcoholic gel, lipogel, one- or multiphase solution or vesicular dispersion or other usual forms, which can also be applied by pens, as tapes, as masks or as sprays. If the topical composition is or comprises an emulsion it can also contain one or more anionic, nonionic, cationic or amphoteric surfactant(s).
Topical compositions in accordance with the invention can be in the form of a liquid, lotion, a thickened lotion, a gel, a cream, a milk, an ointment, a paste, a powder, a make-up, or a solid tube stick and can be optionally be packaged as an aerosol and can be provided in the form of a mousse such as a aerosol mousse, a foam or a spray foam, a spray, a stick, a plaster, a cleanser, a soap, a wipe or a lyophilizate (such as the Pentapharm Dual Vial system).
The topical compositions according to the invention are preferably formulated as an oil-in-water or water-in-oil emulsion, water-in-silicone or silicone-in-water emulsion or as an aqueous serum or aqueous gel in particular as oil-in-water or water-in-oil emulsion.
The topical compositions according to the invention have a pH in the range of 3-10, preferably in the range of pH of 4-8, most preferred in the range of pH 5-7. The pH is adjusted by methods known to a person skilled in the art, e.g. by using an acid such as a hydroxy acid including glycolic acid, lactic acid, malic acid, citric acid and tartaric acid or a base such as e.g. sodium or potassium hydroxide or ammonium hydroxide as well as mixtures thereof.
Preferably, in the compositions according to the invention citric acid in an amount of at least 0.0001 wt.-%, such as e.g. in an amount of 0.01-1 wt.-%, in particular in an amount of 0.01 to 0.5 wt.-% is used for pH adjustment.
The following examples are provided to further illustrate the compositions and effects of the present invention. These examples are illustrative only and are not intended to limit the scope of the invention in any way.
The antimicrobial activity was assessed by determination of the Minimum Inhibitory Concentration (MIC) using the agar dilution method according to DIN 58 940 at the Labor L+SAG, D-Bad Bocklet-Grossenbrach.
Culture plates with a diameter of 5.5 cm were prepared with fresh, kept liquid (50° C.) Mueller-Hinton Agar (double concentrated, Merck 1.05437)/aqua purificata comprising the compound/compound mixtures in the concentrations indicated in Table 1 according to standard methods. After solidifying and drying (about 1 h at 36° C.), the culture plates were inoculated with 1 μl of a suspension of the respective microorganism with the colony forming unit as outlined in table 1. The inoculated plates were then incubated at 36° C. The MIC's (i.e. the concentrations where still no growth could be observed) were determined after 18 h for E. coli, P. aeruginosa and S. aureus; after 48 h for P. acnes and after 78 h for A. brasiliensis and C. albicans. Per sample two culture plates were prepared. As control incubated and non-incubated cultures were used. The incubated control samples showed and the non-incubated control samples did not show microbial growth.
The suspensions of the microorganisms No. 1-4 were prepared by homogeneous suspension of 3-5 colonies of the same morphology in physiological NaCl-solution. The suspensions were adjusted such, that the haze corresponded to the Mac Farland standard 1.0 (about 3.0*108 KBE*/ml). For the preparation of the suspensions of the microorganisms 5 and 6, the microorganisms have been taken with a sterile swab and diluted in an amount of physiological NaCl solution such, that the haze corresponded to the Mac Farland standard 1.0. Afterwards the suspensions of the microorganisms 1 and 3-6 have been further diluted with physiological NaCl-solution in a ratio of 1:10. The colony count was determined using a spiral plater system (see table 2).
Escherichia coli (E. coli)
Pseudomonas aeruginosa
Staphylococcus aureus
Propionibacterium acnes
Aspergillus brasiliensis
Candida albicans
The results are presented in the tables 3-6 below. The synergistic effect is shown by calculation of the ratio [MIC (single)/(MIC (mixture)]. A value of >1 indicates a synergistic effect.
E. coli
P. acnes
P. aeruginosa
S. aureus
A. brasiliensis
C. albicans
E. coli
P. acnes
P. aeruginosa
S. aureus
A. brasiliensis
C. albicans
E. coli
P. acnes
P. aeruginosa
S. aureus
A. brasiliensis
C. albicans
E. coli
P. acnes
P. aeruginosa
S. aureus
A. brasiliensis
C. albicans
Calendula Officinalis Extract,
Buddleja Davidii Extract,
Vulgare, Sodium Benzoate,
Prunus armeniaca
Echinacea purpurea
| Number | Date | Country | Kind |
|---|---|---|---|
| 12182756.2 | Sep 2012 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/066813 | 8/12/2013 | WO | 00 |
