Aqueous composition with a sennoside and a weak base

Abstract

Aqueous composition with a sennoside and a weak base The present invention relates to a cosmetic composition comprising at least one compound according to formula (I) as defined hereinafter, or one of its optical isomers, cis-trans isomers, tautomers or one of its salts in particular organic or mineral basic salts or solvates such as hydrates, at least one weak base, and water, said composition having a pH between 6.0 and 6.5.

Description

[0001] Aqueous composition with a sennoside and a weak base

[0002] The present invention relates to a cosmetic composition comprising:

[0003] (a) at least one compound according to formula (I) as defined hereinafter, or one of its optical isomers, cis-trans isomers, tautomers or one of its salts in particular organic or mineral basic salts or solvates such as hydrates,

[0004] (b) at least one weak base, and

[0005] (c) water, said composition having a pH between 6.0 and 6.5.

[0006] Human skin is composed of two compartments, namely a deep compartment (the dermis) and a surface compartment (the epidermis). The epidermis is in contact with the external environment, and it particularly has the role of protecting the body from dehydration and stress in particular external, chemical or mechanical stress.

[0007] There is still a need for novel cosmetic compositions having advantageous properties, in particular on the skin.

[0008] Sennosides may be advantageous active agents in this aim. Indeed, this type of active agent is known in cosmetics, for example from application JP2002-255733.

[0009] However, sennosides are partially soluble in some solvents such as methanol and acetone (which are not cosmetically acceptable solvents), and are not soluble in water, in particular at ambient temperature. Therefore, they do not allow, per se, the formulation of cosmetic compositions that are stable and applicable on the skin.

[0010] Therefore, the formulator seeks compositions comprising a sennoside such as sennoside which are stable and applicable in particular topically (i.e. on the skin and / or mucosa).

[0011] Such compositions must furthermore comprise a certain quantity of water, in order to be able to formulate a sennoside such as sennoside A in a wide range of cosmetic substrates including lotions, gels or emulsions.

[0012] In this context, the inventors surprisingly discovered that particular bases allow the solubilization of a sennoside such as sennoside A, and are compatible with a formulation in aqueous medium at a given pH. Therefore, the aim of the invention is that of providing a cosmetic composition addressing all these issues.

[0013] Indeed, in this specific case, sennoside A is insoluble in water at its native pH, i.e. around 4.3. It is known that raising the pH of a molecule beyond its final pKa makes the molecule soluble. However, as sennoside A has 4 pKa and its final pKa is equal to 8.2, such a pH results in the formulation of sennoside A beyond 8.3, which is incompatible with topical cosmetic application, in particular on the skin and / or mucosa. Indeed, topical cosmetic compositions, in particular applicable on the skin and / or mucosa, must have an acceptable physiological pH, i.e. between 5.0 and 7.0.

[0014] Surprisingly, as demonstrated in the examples, the Applicant discovered that by adjusting the pH directly with a weak base, it is possible to obtain a clear solution, whereas this is not the case with a strong base.

[0015] Thus, the present invention relates to a cosmetic composition comprising:

[0016] (a) at least one compound according to formula (I) or one of its optical isomers, cis-trans isomers, tautomers or one of its salts in particular organic or mineral basic salts or solvates such as hydrates,

[0017] (b) at least one weak base, and

[0018] (c) water, said composition having a pH between 6.0 and 6.5.

[0019] Preferably, the present invention relates to a cosmetic composition consisting of:

[0020] (a) at least one compound according to formula (I) or one of its optical isomers, cistrans isomers, tautomers or one of its salts in particular organic or mineral basic salts or solvates such as hydrates,

[0021] (b) at least one weak base, and

[0022] (c) water, said composition having a pH between 6.0 and 6.5.

[0023] According to the present invention, and unless indicated otherwise: an "alky radical is a linear or branched saturated hydrocarbon radical, in particular Ci-Ce, preferably C1-C4; a "sugar" radical is a monosaccharide or disaccharide radical. As sugar radical, mention may be made of: sucrose (or saccharose), glucose, galactose, ribose, fucose, maltose, fructose, mannose, arabinose, xylose or lactose;

[0024] "monosaccharide" means a mono-glycoside sugar comprising at least 5 carbon atoms of formula CX(H2O)X, where x is an integer greater than or equal to 5, preferably x is greater than or equal to 6, in particular x is between 5 and 7 inclusive, preferably x = 6. They may be D or L series, and of alpha or of beta anomer, as well as one of their salts or their solvates such as hydrates;

[0025] "disaccharide" means a di-glycoside sugar which is a compound consisting of two glycosides bonded together by O-glycosidic bonds, said compounds consisting of two monosaccharides (also referred to as mono-glycosides) as defined above, said monosaccharide units comprising at least 5 carbon atoms, preferably 6, particularly the mono-glycoside units are bonded together at 1 ,4 or 1 ,6, in a (alpha) or (beta) anomer, each glycoside unit being capable of being L or D series, as well as one of its salts or its solvates such as hydrates. A disaccharide is more particularly a polymer formed from two glycosides (or monosaccharides) having the general formula: -[Cx(H2O)y)]2- or -[(CH2O)X]2-, where x is an integer greater than or equal to 5, preferably x is greater than or equal to 6, in particular x is between 5 and 7 inclusive, preferably x = 6, and y is an integer which represents x - 1 ;

[0026] "organic or mineral basic salt" means a basic salt or alkaline agent such as alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, ammonia, amines, alkanolamines or so-called "basic" amino acid salts such as lysine or arginine;

[0027] "skin" means facial skin and / or body skin, and the scalp;

[0028] "appendages" means eyelashes, eyebrows, nails and hair, and particularly eyelashes and hair; hereinafter, and unless indicated otherwise, the ranges of values are inclusive, in particular in the expressions "between and" and "ranging from ... to ..."; moreover, the expression "at least one" used in the present description is equivalent to the expression "one or more".

[0029] The invention also relates to a method for care of the skin and / or mucosa comprising application of the composition according to the invention on the skin and / or mucosa.

[0030] The invention also relates to the use of a composition according to the invention for care of the skin and / or mucosa. The invention also relates to a final cosmetic composition comprising, in a cosmetically acceptable medium, at least 50% by weight, preferably from 60% to 99%, and more preferably from 70% to 95% with respect to the total weight of the composition of a composition as described above (i.e. comprising ingredients a) to c)). This final composition corresponds in particular to the marketed final cosmetic product.

[0031] Compound according to formula (I) (compound (a))

[0032] The composition according to the invention comprises at least one compound according to formula (I) or one of its optical isomers, cis-trans isomers (such as an alpha or beta anomer), tautomers or one of its salts in particular organic or mineral basic salts or one of its solvates such as hydrates:

[0033] [Chem 1] wherein:

[0034] - R’ and R” are identical or different, preferably identical, and represent an H or a monosaccharide or a polysaccharide including up to 20 sugar units, preferably up to 6 sugar units, in pyranose and / or furanose form and of L and / or D series, said mono- or polysaccharide optionally being substituted by an obligatorily free hydroxyl group, and optionally one or more optionally protected amine function(s), and said monosaccharide or polysaccharide optionally being substituted on its -CH2OH group by a -C(O)-CC>2H group;

[0035] - R represents H or -C-(O)-O-Ri or -Alk-X-R1 , preferably -C-(O)-O-Ri or Alk-O-Ri, where X is O, S or -NRi, preferably O; Ri being H or a saturated or unsaturated hydrocarbon chain, preferably saturated C1-C6, more preferably R1 corresponds to H, and Aik corresponds to a Ci-Ce alkylene group, preferably -CH2-. Advantageously, R’ and R” are identical or different and represent a monosaccharide or a polysaccharide containing up to 6 sugar units, in pyranose and / or furanose form and of L and / or D series, said mono- or polysaccharide having at least one obligatorily free hydroxyl function and / or optionally one or more obligatorily protected amine function(s).

[0036] Advantageously, the monosaccharide is chosen from D-glucose, D-galactose, D- mannose, D-xylose, D-lyxose, L-fucose, L-arabinose, L-rhamnose, D-glucuronic acid, D- galacturonic acid, D-iduronic acid, N-acetyl-D-glucosamine and N-acetyl-D-galactosamine. The monosaccharide advantageously denotes D-glucose, L-rhamnose, D-xylose, N-acetyl- D-glucosamine or L-fucose, and more preferably D-glucose.

[0037] Advantageously, the polysaccharide containing up to 6 sugar units is chosen from D-maltose, D-lactose, D-cellobiose, D-maltotriose, a disaccharide associating a uronic acid chosen from D-iduronic acid or D-glucuronic acid with a hexosamine chosen from D- galactosamine, D-glucosamine, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, a disaccharide associating L-rhamnose and D-galactose, an oligosaccharide containing at least one xylose which can advantageously be chosen from xylobiose, methyl-p- xylobioside, xylotriose, xylotetraose, xylopentaose and xylohexaose and in particular xylobiose which is composed of two xylose molecules bonded by a 1-4 bond.

[0038] More preferably, R’ and R” are identical or different and represent a monosaccharide chosen from D-glucose, D-xylose, L-fucose, L-rhamnose, D-galactose and D-maltose, preferably D-glucose.

[0039] The monosaccharide or polysaccharide of R’ and / or R” may be substituted on one or more hydroxymethyl residue(s) by a -C(O)-COOH group.

[0040] Preferably, the compound according to formula (I) or one of its optical isomers, cistrans isomers (such as an alpha or beta anomer), tautomers or one of its salts in particular organic or mineral basic salts or one of its solvates such as hydrates, is chosen from sennosides A, B, C, D, E and F, preferably it is chosen from sennosides A and B, more preferably the compound according to formula (I) is sennoside A or one of its salts. The compound according to formula (I) or one of its optical isomers, cis-trans isomers (such as an alpha or beta anomer), tautomers or one of its salts in particular organic or mineral basic salts or one of its solvates such as hydrates, preferably sennoside A or one of its salts, is present in solubilized form in the composition. "In solubilized form" means that said compound does not form crystals visible to the naked eye in the composition.

[0041] Sennoside A (C42H38O20) (or (9R)-9-[(9R)-2-carboxy-4-hydroxy-10-oxo-5- [(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-9H-anthracen-9-yl]-4- hydroxy-10-oxo-5-[(2S,3R,4S,5S,6R)-3, 4, 5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-9H- anthracene-2-carboxylic acid under its IIIPAC name) is the chemical compound according to the following formula (I’):

[0042] [Chem 2]

[0043] Its CAS number is 81-27-6. It is a derivative of anthraquinone, which is found in plants of the Senna genus. It is typically presented in the form of a very hygroscopic yellow powder.

[0044] Sennoside A has 4 pKa, the values of which are pKa1 = 3.3, pKa2 = 3.9, pKa3 = 7.5 and its final pKa (pKa4) is equal to 8.2.

[0045] The compound according to formula (I), preferably sennoside A may also be presented in salt form. "Salt" means a cosmetically acceptable salt, i.e. compatible with application on the skin, mucosa and / or skin appendages. The salt of compound according to formula (I), preferably the salt of sennoside A, may be an alkali metal or alkaline-earth salt, preferably a calcium, magnesium, sodium or potassium salt.

[0046] Typically, the salt of compound according to formula (I), preferably the sennoside salt such as the salt of sennoside A, may exist once the compound has been introduced into the composition. Indeed, the compound according to (I) is introduced in non-salified form into the composition.

[0047] Sennoside A is for example marketed by INTERCHIM under the name Sennoside A.

[0048] Preferably, the composition comprises between 0.1 and 5% by weight of the compound according to formula (I) or one of its optical isomers, cis-trans isomers (such as an alpha or beta anomer), tautomers or one of its salts in particular organic or mineral basic salts or one of its solvates such as hydrates, with respect to the total weight of the composition, preferably between 0.2 and 4% by weight, preferably between 0.3 and 3% by weight, preferably between 0.4 and 1% by weight.

[0049] Preferably, the composition comprises between 0.1 and 10% by weight of sennoside A or one of its salts with respect to the total weight of the composition, preferably between 0.2 and 5% by weight, preferably between 0.3 and 3% by weight, preferably between 0.4 and 1 % by weight.

[0050] Weak base (compound (b))

[0051] The composition according to the invention comprises at least one weak base. A weak base is a base which is not dissociated completely in water.

[0052] "Weak base" means a base belonging to an acid-base pair of pKa between 0 and 14.

[0053] The weak base may be mineral or organic.

[0054] As mineral weak bases, mention may be made of ammonia or aluminum hydroxide.

[0055] Preferably, the weak base is chosen from organic weak bases, preferably from alpha-amino acids.

[0056] Alpha-amino acids comply with the formula of the type H2N-HCR-COOH, where R is the side chain identifying the alpha-amino acid. Preferably, the alpha-amino acids are proteinogenic.

[0057] Preferably, the alpha-amino acid is chosen from L-arginine, L-alanine, L-asparagine, L-aspartate, L-cysteine, L-glutamate, L-glutamine, L-glycine, L-histidine, L-isoleucine, L- leucine, L-lysine, L-methionine, L-phenylalanine, L-proline, L-serine, L-threonine, L- tryptophan, L-tyrosine and L-valine. Preferably, the weak base is arginine (or L-arginine).

[0058] The composition according to the invention may comprise at least one base at an active substance concentration ranging from 0.01 % to 5% by weight, with respect to the total weight of the composition, in particular from 0.1% to 1% by weight, preferably ranging from 0.15% to 0.6% by weight.

[0059] Water (compound (c))

[0060] The composition according to the invention comprises water.

[0061] The water used may be sterile demineralized water and / or floral water such as rose water, cornflower water, chamomile water or linden water, and / or a spring or natural mineral water, such as VITTEL water, LUCAS water or LA ROCHE POSAY water.

[0062] The composition preferably comprises at least 30% by weight of water, with respect to the total weight of the composition, preferably at least 50% by weight, preferably at least 60% by weight, and preferably at least 70% by weight.

[0063] The composition preferably comprises from 30% to 98% by weight of water with respect to the total weight of the composition, more preferably from 50% to 97% by weight, even more preferably from 70% to 95% by weight. pH of the composition

[0064] The composition according to the invention has a pH between 6.0 and 6.5.

[0065] The weak base is used to adjust the final pH of the composition between 6.0 and 6.5.

[0066] Preferably, the composition according to the invention is substantially free from strong base. "Substantially free from strong base" means that the composition comprises less than 1% by weight, preferably less than 0.5% by weight, preferably less than 0.01% by weight with respect to the total weight of the composition of strong base. Preferably, the composition according to the invention is totally free from strong base.

[0067] Preferably, the present invention relates to a cosmetic composition comprising: (a) sennoside A or one of its salts, (b) arginine, and

[0068] (c) water, said composition having a pH between 6.0 and 6.5.

[0069] Preferably, the present invention relates toa cosmetic composition consisting of:

[0070] (a) sennoside A or one of its salts,

[0071] (b) arginine, and

[0072] (c) water, said composition having a pH between 6.0 and 6.5.

[0073] The composition according to the invention may also contain usual ingredients in the cosmetics field, such as preservatives, perfumes, fillers, oils, waxes, pasty fats, sun protection filters or UV filters, odor absorbers, dyestuffs, alkaline agents, sequestering agents, or active agents.

[0074] The quantities of these various ingredients are conventionally the quantities used in the field considered, for example from 0.01 to 20% of the total weight of the composition. These ingredients, depending on their nature, may be introduced into the oily phase and / or into the aqueous phase.

[0075] Obviously, those skilled in the art will take care to choose the optional compound(s) to add to the composition according to the invention and their quantities in such a way that the advantageous properties intrinsically associated with the composition according to the invention are not altered, or are not substantially altered, by the envisaged addition.

[0076] The composition according to the invention may be obtained conventionally by those skilled in the art.

[0077] The invention also relates to a final cosmetic composition comprising, in a cosmetically acceptable medium, at least 50% by weight with respect to the total weight of the composition of a composition as described above (i.e. comprising ingredients a) to c)), preferably from 60 to 99% by weight, more preferably from 70 to 95% by weight. The final composition corresponds in particular to the marketed final cosmetic product, based on sennoside. Cosmetically acceptable medium means a medium compatible with the skin and / or its appendages. The invention also relates to a method for care of the skin and / or mucosa comprising application of the composition according to the invention or the final composition according to the invention on the skin and / or mucosa.

[0078] The invention also relates to the use of a composition according to the invention or the final composition according to the invention for care of the skin and / or mucosa.

[0079] The following examples make it possible to understand the invention better, without being in any way limitative. The raw materials are referred to with the chemical or INCI name thereof. The amounts indicated are as a % by weight of raw materials with respect to the total weight of the composition (% w / w), unless specified otherwise.

[0080] Examples

[0081] Example 1 : preparation of a composition according to the invention and evaluation compared to comparative compositions

[0082] A composition according to the invention is compared with counter-examples.

[0083] Procedure

[0084] The composition according to the invention of Table 1 below is prepared as follows: Sennoside A in powder form is placed in a beaker under a magnetic stirrer, followed by water, the mixture is not homogeneous. The pH is then adjusted dropwise with arginine. The whole is left under stirring for some time to stabilize the pH.

[0085] In the case of the counter-examples:

[0086] The same method is used in counter-examples 1 and 2 with a strong base (NaOH). However, the pH adjustment is extremely difficult to carry out: when the pH is for example 5.8 (counter-example 1), sennoside A is not totally solubilized. A very slight pH variation, for example of 0.1 to obtain solubilization (counter-example 2), does not allow reproducibility.

[0087] [Table 1]

[0088] Sennoside A is totally insoluble in water at native pH (4.3); the dispersion (counter-example without base) is opaque yellow.

[0089] It is possible to obtain a perfect solubility that is stable over time of 0.5% sennoside A by weight by varying the pH of this solution with a weak base such as arginine. Indeed, at a pH between 6.0 and 6.5, the solution (example 1 according to the invention) is clear and free from recrystallization over time.

[0090] Obtaining the sennoside A solution by passing directly to a pH 6.0 is easier than with a strong base, where the introduction contents are low, i.e. of the order of 10'2to 10'3(counter- examples 1 and 2).

Claims

CLAIMS1. Cosmetic composition comprising:(a) at least one compound according to formula (I) or one of its optical isomers, cis-trans isomers, tautomers or one of its salts in particular organic or mineral basic salts or solvates such as hydrates:[Chem 1]wherein:- R’ and R” are identical or different, preferably identical, and represent an H or a monosaccharide or a polysaccharide including up to 20 sugar units, preferably up to 6 sugar units, in pyranose and / or furanose form and of L and / or D series, said mono- or polysaccharide optionally being substituted by an obligatorily free hydroxyl group, and optionally one or more optionally protected amine function(s), and said monosaccharide or polysaccharide optionally being substituted on its -CH2OH group by a -C(O)-CC>2H group;- R represents H or -C-(O)-O-Ri or -Alk-X-R1 , preferably -C-(O)-O-Ri or Alk-O-Ri, where X is O, S or -NRi, preferably O; R1 being H or a saturated or unsaturated hydrocarbon chain, preferably saturated C1-C6, more preferably R1 corresponds to H, and Aik corresponds to a Ci-Ce alkylene group, preferably -CH2-,(b) at least one weak base, and(c) water, said composition having a pH between 6.0 and 6.5.

2. Composition according to claim 1 , wherein the compound according to formula (I) is such that R’ and R” are identical and represent a monosaccharide chosen from D-glucose, D-galactose, D-mannose, D-xylose, D-lyxose, L-fucose, L-arabinose, L-rhamnose, D-glucuronic acid, D-galacturonic acid, D-iduronic acid, N-acetyl-D-glucosamine and N-acetyl-D-galactosamine, preferably chosen from D-glucose, L-rhamnose, D-xylose, N-acetyl-D-glucosamine and L-fucose, and more preferably D-glucose; preferably, the compound according to formula (I) or one of its optical isomers, cis-trans isomers, tautomers or one of its salts in particular organic or mineral basic salts or one of its solvates such as hydrates, is chosen from sennosides A, B, C, D, E and F, preferably it is chosen from sennosides A and B.

3. Composition according to one of the preceding claims, wherein the compound according to formula (I) is sennoside A or one of its salts.

4. Composition according to one of the preceding claims which comprises between 0.1 and 10% by weight of compound according to formula (I) with respect to the total weight of the composition, preferably between 0.2 and 5% by weight, preferably between 0.3 and 3% by weight, preferably between 0.4 and 1% by weight.

5. Composition according to one of the preceding claims, wherein the weak base is mineral or organic, preferably chosen from ammonia, aluminum hydroxide and alpha-amino acids, preferably from alpha-amino acids.

6. Composition according to one of the preceding claims, wherein the weak base is arginine.

7. Composition according to one of the preceding claims, wherein the weak base is present at an active substance concentration ranging from 0.01% to 5% by weight, with respect to the total weight of the composition, in particular from 0.1% to 1% by weight, preferably ranging from 0.15% to 0.6% by weight.

8. Composition according to one of the preceding claims, which comprises at least 30% by weight of water with respect to the total weight of the composition, preferably at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight; preferably comprises from 30% to 98% by weight of water with respect to the total weight of the composition, more preferably from 50% to 97% by weight, even more preferably from 70% to 95% by weight.

9. Composition according to one of the preceding claims, which consists of:(a) at least one compound according to formula (I) or one of its optical isomers, cistrans isomers, tautomers or one of its salts in particular organic or mineral basic salts or solvates such as hydrates,(b) at least one weak base, and(c) water, said composition having a pH between 6.0 and 6.5.

10. Composition according to one of the preceding claims, which is substantially free from strong base, preferably which is totally free from strong base.

11. Final cosmetic composition comprising, in a cosmetically acceptable medium, at least 50% by weight, preferably from 60% to 99% by weight, more preferably from 70% to 95% with respect to the total weight of the composition of a composition according to claims 1 to 10.

12. Method for care of the skin and / or mucosa comprising application of the composition according to one of the preceding claims on the skin and / or mucosa.

13. Use of a composition according to one of claims 1 to 10 or 11 for care of the skin and / or mucosa.

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