WO2013093832A2

WO2013093832A2 - Cosmetic process for removing makeup from and/or cleansing the skin using a nucleophilic agent and a nitrogen-comprising or phosphorus-comprising agent with a pka of greater than 11

Info

Publication number: WO2013093832A2
Application number: PCT/IB2012/057526
Authority: WO
Inventors: Anne-Laure Bernard; Henri Samain; Myriam Kauffmann
Original assignee: L'oreal
Priority date: 2011-12-22
Filing date: 2012-12-20
Publication date: 2013-06-27
Also published as: WO2013093832A3; FR2984734A1; FR2984734B1

Abstract

The subject of the present invention is a cosmetic process for removing makeup from and/or cleansing the skin, which comprises at least bringing the skin into contact with at least one nucleophilic agent and at least one nitrogen-comprising or phosphorus-comprising agent with a p Ka of greater than 11, distinct from said nucleophilic agent.

Description

COSMETIC PROCESS FOR REMOVING MAKEUP FROM AND/OR CLEANSING THE SKIN USING A NUCLEOPHILIC AGENT AND A NITROGEN-COMPRISING OR PHOSPHORUS-COMPRISING AGENT WITH A PKA OF GREATER THAN 11

The present invention relates to a cosmetic process for removing makeup from and/or cleansing the skin. It is more particularly directed toward removing makeup from skin which has a coloration resulting from the skin being brought into contact with carbonyl compounds, and in particular skin which has been colored by applying dihydroxy acetone (DHA).

In general, coloration of the skin may be the result of it being intentionally or unintentionally brought into contact with carbonyl compounds More particularly, these carbonyl compounds are capable of reacting with the amino groups of amino acid residues, in particular the amino acid residues of proteins, thus resulting in the formation of products that will color the skin.

In certain situations, this coloration may be provided intentionally, by applying cosmetic products intended for making up the skin, for example for artificial tanning of the skin. To this effect, dihydroxyacetone or DHA is a particularly interesting product which is commonly used in the cosmetics industry as an agent for artificially tanning the skin; when applied to skin, it makes it possible to obtain a tanning or browning effect. It may also involve temporary marking of the skin for dermatological or experimental purposes.

In other cases, coloration of the skin may be caused unintentionally, owing in particular to the action of certain pollutants on the skin. For example, decomposition of skin lipids can be caused by ozone and result in the formation of aldehyde or ketone compounds capable of inducing colored effects. Generally, the amounts of products formed are low, and do not necessarily produce colored effects. However, with time, a certain coloration of the skin can appear.

In all these situations, the person may wish to eliminate or fade the coloration of the skin. Thus, in the case of an intentional coloration, the person may wish to modify the color, for example when finding the coloration too strong, badly placed, heterogeneous, mottled or overloaded in certain areas, or poorly delimited, or quite simply when tired of the result. In particular, the user of a self-tanning product may wish to get rid of the tanning effect after a certain amount of time. The removal of a coloration intentionally brought to the skin may also be required in order to erase a tattoo, or else to draw a reverse tattoo on a colored background.

Equally, for obvious reasons, a person may wish to remove the effects unintentionally induced by bringing the skin into contact with certain carbonyl compounds, in particular to get rid of an unintentional coloration of the skin, or quite simply to remove the products unintentionally formed which can sometimes cause an odor which is not appreciated.

To this effect, washing and/or rubbing the skin, for example with cotton wool, are unfortunately ineffective in removing the products formed by the action of carbonyl compounds, and do not therefore make it possible to erase the coloration of the skin induced by these products.

Equally, waiting for the skin to desquamate in order to remove the coloration is not a satisfactory solution, since this takes time (typically from a few days to several weeks), and only the effects on the most superficial layers are removed.

There remains therefore a need to have an effective means for removing makeup from and/or cleansing the skin, especially for removing the effects induced by intentionally or unintentionally bringing the skin into contact with carbonyl compounds, in particular for removing the products formed or the coloration of the skin induced by such carbonyl compounds.

There remains more particularly a need to have an effective means for removing makeup from skin which has been colored by application of dihydroxyacetone (DHA).

The present invention is specifically directed toward meeting these needs.

More particularly, according to a first of its aspects, the present invention relates to a cosmetic process for removing makeup from and/or cleansing the skin, which comprises bringing the skin into contact with at least one nucleophilic agent and at least one nitrogen-comprising or phosphorus-comprising agent with a pKa of greater than 1 1, distinct from said nucleophilic agent.

The term "the skin" is intended to mean the entire skin of the body, including the lips, the scalp and the mucous membranes.

The nucleophilic agent is more particularly a thiol derivative.

The process of the invention is more particularly intended for removing makeup from and/or cleansing skin which has been intentionally or unintentionally brought into contact with carbonyl compounds in their native, acetal, ketal, hemiacetal or hemiketal form. Such carbonyl compounds may be more particularly:

- sugars. For the purpose of the invention, the term "sugar" is intended to mean compounds which have one or more monosaccharides. A monosaccharide is a unit derived from a carbohydrate of formula C_n(H₂0)_n_i or (CH₂0)_n with n ranging from 3 to 6.

It may more particularly be a question of simple sugars (small molecules composed of one or two monosaccharides) or complex sugars (long chains composed of two or more monosaccharide units) also called polysaccharides, in particular oligosaccharides. Reducing sugars, such as erythrulose, are in particular used;

- aldehydes, ketones or activated ketones. The term "activated ketone" is intended to mean a compound comprising a ketone function and bearing, on an adjacent carbon or adjacent carbons of the ketone function, other functions capable of increasing its reactivity, in particular an alkenyl function, a hydroxyl function, another carbonyl function such as a ketone, an aldehyde function, or an acid, ester or amide function.

The ketones are more particularly compounds of formula

RC(0)R'

in which:

R represents a linear or branched, saturated or unsaturated Ci to C₃o hydrocarbon- based chain optionally substituted with one or more alkenyl, alkynyl, hydroxyl or carbonyl groups; or R represents an aryl group; and

R' represents a Ci to C₃o alkyl group or an aryl group.

More preferentially, the R group and/or the R group bear(s) a function on the carbon in the alpha position, such as an alkenyl, alkynyl, hydroxyl or carbonyl function, and/or bear(s), on the carbon in the beta position, a function such as an alkenyl, alkynyl, hydroxyl or carbonyl function.

R may be more particularly CH₂OH.

In particular, R et R' may be CH₂OH.

In the case of the aldehydes, the compounds may correspond to the formula:

RC(0)H

in which:

R represents a linear or branched, saturated or unsaturated Ci to C₃o hydrocarbon-based chain optionally substituted with one or more alkenyl, alkynyl, hydroxyl or carbonyl groups; or R represents an aryl group.

The R group may bear a function on the carbon in the alpha position, such as an alkenyl, alkynyl, hydroxyl or carbonyl function, and/or bear, on the carbon in the beta position, a function such as an alkenyl, alkyne, hydroxyl or carbonyl function. Thus, they may in particular be aldehydes of formula CRi=CR₂-CHR₃-C(0)H where Ri, R₂ et R₃ represent H or CH₃.

They may also be compounds derived from aldehydes, of acetal or hemiacetal type, in particular of formula

H

R C OR"

OR"

in which R is as defined previously, and R' ' represents, indifferently from one another, a hydrogen atom or a Ci to C₅ alkyl group, or R" forms, with the oxygen atom

H C-CH

2 \ / ²

which bears it, a ring ⁰

The process of the invention is more particularly intended for removing makeup from and/or cleansing skin on which "long- lasting" or "semi-permanent" skin- dyeing or makeup products have been applied.

According to one particular embodiment, the process of the invention is intended for removing makeup from and/or cleansing skin which has been previously colored with carbonyl compounds, in particular with dihydroxyacetone (DHA).

According to one particularly preferred embodiment of the invention, said nucleophilic agent and said nitrogen-comprising or phosphorus-comprising agent with a pKa of greater than 1 1 are used in one or more compositions having a pH ranging from 5 to 13, preferably from 7 to 12, especially from 7 to 1 1 , in particular from 8 to 10 and more particularly from 8 to 9.5.

According to one particular embodiment, the process of the invention uses at least one thiolate derivative and at least one guanidinium ion or one of its derivatives.

Surprisingly, the inventors have discovered that the use of such a combination of active agents makes it possible to obtain an effective makeup-removing effect.

Equally, advantageously, bringing such a system of active agents into contact with the skin from which makeup is to be removed and/or which is to be cleansed does not induce any secondary problems, such as redness or irritation, and does not affect the structure the skin, in particular does not impair intercellular linkages (corneosomes). The combination under consideration according to the invention can be used with one or more additional compounds, chosen in particular from pH-regulating agents, chaotropic agents, additional reducing agents, simple amines or polyamines, desquamating agents and scrubbing agents.

As expanded upon below, bringing the skin into contact with the combination of active agents according to the invention is understood to mean more particularly the application to and/or the injection into the thickness of the skin of one or more compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11.

Other characteristics, variants and advantages of the process of the invention will emerge more clearly from reading the description, examples and figures which will follow, given by way of illustration and without implied limitation.

In the continuation of the text, the expressions "between ... and "ranging from ... to ..." and "varying from ... to ..." are equivalent and are intended to mean that the limits are included, unless otherwise mentioned.

Unless otherwise indicated, the expression "comprising a" should be understood as "comprising at least one". NUCLEOPHILIC AGENT

As touched on above, the present invention uses, according to a first of its aspects, at least one nucleophilic agent.

The term "nucleophilic agent" is intended to denote a compound comprising at least one nucleophilic chemical function, that is to say a function attracted by electrophilic species. The term "electrophile" is understood to mean a charged or partially charged species.

A nucleophile reacts by donating electrons to the electrophilic compound.

The nucleophilic agent can be a molecule or an ion which has a non-bonding electron pair. It may or may not be negatively charged.

The nucleophilic agent can thus react with an electrophilic species in order to create a new covalent bond or else to produce an electrostatic bond.

According to one particular embodiment, the nucleophilic agent is used in a medium with a pH ranging from 5 to 13, especially from 7 to 12 and in particular from 8 to 10. Preferably, the medium is an aqueous medium, as subsequently described more specifically.

Said nucleophilic agent can more particularly be chosen from compounds having a nucleophilic function chosen from the following functions:

- thiolate (RS );

- halide, in particular iodide (Γ), bromide (Br ), chloride (CI ) or fluoride (F), and oxidized halide functions, such as, for example, hypoiodite (10 );

- cyanate (OCN ) and its derivatives, such as, for example, isocyanate or isothiocyanate;

- sulfite (SO₃ ² ) and other oxidized sulfur functions, such as, for example, bisulfite or hydrogen sulfite (HSO3 ), thiosulfate (S2O3² ) and tetrathionate (S4O6² ); and

- phosphite (HPO₃ ² ) or phosphine and its derivatives, in particular triarylphosphine, trialkylphosphine, such as, for example, phosphinetripropionic triacid, or triphenylphosphine.

The nucleophilic agent can be chosen from plant or biotechnological extracts or their derivatives comprising these functions, such as, for example, coleus extracts.

According to one particularly preferred embodiment, said nucleophilic agent is chosen from thiol derivatives.

Preferably, said nucleophilic agent exhibits a negatively charged thiol function, also known as thiolate (RS ) function.

It is understood that the charged or uncharged form of said nucleophilic agent will depend on the pH of the medium in which it is used.

In particular, said thiol derivative can be chosen from:

- cysteine and its N-alkylated, N-acylated or C-alkylated derivatives; homocysteine and its N-alkylated, N-acylated or C-alkylated derivatives; and peptides comprising them, such as, for example, reduced glutathione;

- cysteamine and its N-alkylated or N-acylated derivatives;

- thioglycolic acid and its derivatives, thiolactic acid and its derivatives, mercaptopropionic acid and its derivatives.

Preferably, said nucleophilic agent exhibits a limited reducing power. According to one particularly preferred embodiment, said nucleophilic agent is chosen from cysteine or one of its N-alkylated, N-acylated or C-alkylated derivatives; homocysteine and its N-alkylated, N-acylated or C-alkylated derivatives; and peptides comprising them, such as, for example, reduced glutathione, these compounds exhibiting in particular a negatively charged thiol function.

Preferably, said nucleophilic agent is chosen from cysteine or one of its N- alkylated, N-acylated and C-alkylated derivatives, in particular exhibiting a negatively charged thiol function.

In particular, said nucleophilic agent can be chosen from L-cysteine and N- acetyl-L-cysteine, in particular exhibiting a negatively charged thiol function.

Preferably, said nucleophilic agent is N-acetyl-L-cysteine, in particular exhibiting a negatively charged thiol function.

According to another particular embodiment, said nucleophilic agent is chosen from compounds having an isocyanate function.

According to yet another particular embodiment, said nucleophilic agent is chosen from compounds having a halide function.

NITROGEN-COMPRISING OR PHOSPHORUS-COMPRISING AGENT WITH A pKa OF GREATER THAN 11

As specified above, the present invention uses, according to another of its aspects, at least one nitrogen-comprising or phosphorus-comprising agent with a pKa of greater than 11.

Natural marine or plant or biotechno logical extracts or their derivatives may be concerned.

Preferably, said nitrogen-comprising or phosphorus-comprising agent exhibits a pKa of greater than 12.

According to one particular embodiment, said agent with a pKa of greater than 11 can be provided in a positively charged form.

It is understood that the charged or uncharged form of said agent with a pKa of greater than 11 will depend on the pH of the medium in which it is used.

According to one particularly preferred embodiment, said agent with a pKa of greater than 11 is used in a medium with a pH ranging from 5 to 13, preferably from 7 to 12, especially from 7 to 11, in particular from 8 to 10 and more particularly from 8 to 9.5. Preferably, the medium is an aqueous medium, as subsequently described more specifically. According to one particular embodiment, said agent with a pKa of greater than 11 is chosen from nitrogen-comprising agents.

It can more particularly be chosen from guanidine or one of its derivatives; imidazole or a compound comprising an imidazolyl group; or pyrrole or a compound comprising a pyrrolyl group.

Preferably, said nitrogen-comprising agent is chosen from guanidine and its derivatives, preferably exhibiting a positively charged guanidine function.

Said nitrogen-comprising agent according to the invention can thus be a compound of formula:

NHR=C(NR'R"₂)⁺

in which R, R' and R" are chosen, independently of one another, from a hydrogen and an alkyl group having from 1 to 6 carbon atoms.

Preferably, said agent with a pKa of greater than 11 is the guanidinium ion (R, R' and R" represent hydrogen atoms), more particularly used in the form of guanidine carbonate, of guanidine hydroxide or of guanidine thiocyanate.

According to one particular embodiment, said nucleophilic agent is a thiol derivative, chosen in particular from cysteine and its N-alkylated, N-acylated and C- alkylated derivatives, preferably exhibiting a negatively charged thiol function, and said agent with a pKa of greater than 11 is guanidine or one of its derivatives, preferably exhibiting a positively charged guanidine function.

Preferably, the invention uses N-acetyl-L-cysteine and the guanidinium ion, in particular in the form of guanidine carbonate.

According to one particular embodiment, said nucleophilic agent and said agent with a pKa of greater than 11, in particular as defined previously, are used in a nucleophilic agent/agent with a pKa of greater than 11 molar ratio ranging from 10 to 1, in particular from 5 to 1 and more particularly of approximately 1.

Thus, according to one particular embodiment, the invention uses a thiol derivative, in particular as defined previously, and a guanidinium ion or one of its derivatives, in a thiolate derivative/guanidinium ion molar ratio ranging from 10 to 1, in particular from 5 to 1 and more preferentially of approximately 1. PROCESS

According to a first embodiment variant, the process for removing makeup from and/or cleansing the skin according to the invention comprises at least the steps consisting in:

(i) bringing said skin into contact with a composition comprising at least said nucleophilic agent, in particular a thiol derivative; and

(ii) bringing said skin into contact with a composition comprising at least said agent with the pKa of greater than 1 1, in particular a guanidinium ion or one of its derivatives;

it being possible for steps (i) and (ii) to be carried out consecutively in the chronological order (i) and then (ii), or in the reverse order (ii) and then (i).

In the context of this embodiment variant, said nucleophilic agent and said agent with a pKa of greater than 11 are formulated in two separate compositions. According to another variant of the process of the invention, said nucleophilic agent and said agent with a pKa of greater than 11 are formulated within one and the same composition.

Preferably, the composition is obtained, prior to being brought into contact with the skin, by extemporaneous mixing of at least one composition comprising said nucleophilic agent and of at least one composition comprising said agent with a pKa of greater than 11.

According to yet another of its aspects, the present invention relates to a kit for removing makeup from and/or cleansing the skin, comprising, in separate containers, at least one nucleophilic agent and at least one nitrogen-comprising or phosphorus- comprising agent with a pKa of greater than 1 1, distinct from said nucleophilic agent, in particular as defined previously.

The nucleophilic agent is more particularly a thiol derivative.

Said kit may additionally comprise at least one means for bringing the skin into contact with said active agents, in particular a means for application to or injection into the thickness of the skin, as described below.

Thus, the present invention relates to a cosmetic kit for removing makeup from and/or cleansing the skin, comprising, in separate containers, at least one first composition comprising a nucleophilic agent that is a thiol derivative, at least one second composition comprising a nitrogen-comprising or phosphorus-comprising agent with a pKa of greater than 11, distinct from said nucleophilic agent, and at least one means for application of a composition to the skin or one means for injection of a composition into the thickness of the skin.

According to another particular embodiment, said kit can also comprise, in a separate container, an additional composition comprising one or more supplementary active agents, in particular as defined subsequently.

According to a first embodiment variant, the operation in which said active agents are brought into contact with the skin to be treated can comprise, or even consist of, the application to the skin of said composition or compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11.

Said composition or compositions can be applied using the palm of the hand or the fingers, or else by conventional application means, such as, for example, using a sponge, a brush, a patch or an iontophoretic system.

According to another variant of the process of the invention, the operation in which said active agents are brought into contact with the skin to be treated can comprise, or even consist of, the injection into the thickness of the skin of one or more compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11.

It is understood that the injection according to the invention is restricted to a superficial region. It is more particularly an intraepidermal and/or intradermal injection.

Mention may be made, among the injection means suitable for an intraepidermal or intradermal injection, for example, of a syringe, microneedle rollers or patches, or the needles normally used for mesotherapy, also known as mesolift or mesoglow when it is carried out on the face.

Of course, the process of the invention can combine these two embodiment variants. In other words, the process of the invention can comprise the application to and/or the injection into the thickness of the skin of one or more compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11. According to one particular embodiment, the operation in which the skin is brought into contact with said nucleophilic agent and/or said agent with a pKa of greater than 11 according to the invention can be accompanied by the use of one or more means, normally used, to promote the penetration of said agent or agents into the skin.

For example, the process can additionally comprise the use, in said composition or compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11 according to the invention and/or in an additional composition, of compounds which promote penetration into the skin, such as a solvent, a surfactant or a hydrotrope, for example benzyl alcohol or propylene carbonate.

According to another particular embodiment, the skin to be treated can be subjected, at least in part, prior to, simultaneously with or subsequent to bringing it into contact with said active agents, to a mechanical action, such as a micropeeling or a controlled chemical peeling, to an energetic action, such as the application of heat, of electric currents or of electromagnetic waves, submission to microwaves, laser, ultrasound, etc.

According to a further particular embodiment, it is possible to create a mechanical tension on the skin to be treated, prior to, simultaneously with or subsequent to bringing it into contact with said active agents.

Moreover, the process of the invention may comprise one or more steps, subsequent to bringing the skin into contact with said active agents, of washing and/or rubbing said skin.

Preferably, these steps of washing and/or rubbing the skin are performed at the end of a period of from 1 to 30 minutes following the step of bringing the skin into contact with said active agents, in particular after a period of from 5 minutes to 15 minutes.

These washing and/or rubbing steps can consist in washing the skin with water and/or rubbing the skin with cotton wool, a tissue or any other means commonly used for removing makeup from the skin. This step can also be carried out with a scrubbing and/or exfoliating composition. COMPOSITIONS

Said composition or compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11 comprise a physiologically acceptable medium.

The term "physiologically acceptable medium" is intended to mean a medium devoid of toxicity and compatible with the application and the penetration, or the injection into the thickness of the skin, of the composition.

According to one particular embodiment, said composition or compositions, in particular when they are intended for injection into the thickness of the skin, are sterile. The term "sterile" is intended to describe an environment devoid of microbial contamination capable of guaranteeing that the compound and/or the composition in which it is present has the safety required for administration in the skin, in particular intraepidermal and/or intradermal administration. In particular, it is essential for the composition formed of the physiologically acceptable medium comprising said compound, and which has to be administered according to an injection technique, to be devoid of any impurity or contaminant of microbial origin capable of initiating an adverse side reaction in the host organism.

The physiologically acceptable medium is more particularly an aqueous medium. The aqueous medium can be formed of water and/or of one or more water- miscible organic solvents, such as, for example, chosen from Ci_s monoalcohols, in particular Ci_₅ monoalcohols. Preferably, the aqueous medium is constituted of water.

A composition according to the invention can comprise water in a content ranging from 0% to 98% by weight and more particularly from 50% to 90% by weight, relative to its total weight.

The physiologically acceptable medium in the case of microinjection can be isotonic with respect to serum.

The concentration of nucleophilic agent and/or agent with a pKa of greater than 1 1 in said composition(s) can be between 0.01 and 5 mol/1, in particular between 0.05 and

I mol/1.

In particular, the contents of nucleophilic agent and of agent with a pKa of greater than 1 1 in said composition or compositions are such that a mixture of the compositions comprises said nucleophilic agent and said agent with a pKa of greater than

I I in a molar ratio ranging from 10 to 1 , in particular from 5 to 1 and more particularly of approximately 1.

As mentioned previously, said composition or compositions exhibit more particularly a pH ranging from 5 to 1 1 , preferably between 7 and 10 and more preferentially between 8 and 9.5.

The pH of said composition or compositions can be adjusted by addition of a pH-regulating agent, chosen in particular from citric acid and sodium hydroxide.

As described below, the pH-regulating agent can be used in said composition or compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 1 1 , and/or in an additional composition. Supplementary active agents

According to one particular embodiment, the process of the invention can use, in addition to said nucleophilic agent and said agent with a pKa of greater than 11, one or more supplementary cosmetic active agents.

They can more particularly be active agents chosen from:

- chaotropic agents, such as, for example, urea;

- additional reducing agents, such as, for example, ascorbic acid;

- amines or poly amines;

- desquamating agents, such as urea; beta-hydroxy acids (BHAs), for example salicylic acid and its derivatives, such as 5-(n-octanoyl)salicylic acid; alpha- hydroxy acids (AHAs), glycolic, citric, lactic, tartaric, malic or mandelic acids; 4-(2- hydroxyethyl)piperazine-l-propanesulfonic acid (HEPES); Sophora japonica extract; honeys; N-acetylglucosamine; sodium methylglycine diacetate, and mixtures thereof;

- dermo-relaxing agents, for example manganese gluconate, wild yam, rock samphire, glycine and alverine;

- anti-inflammatory agents, such as licorice derivatives and glycerrhetinic acid, Aloe vera, Aloe ferox, extracts of yeasts, such as Saccharomyces cerevisiae, extracts of rose and rosemary, of camomile, of common comfrey, allantoin, D-panthenol, azulene and chamazulene;

- agents which stimulate renewal of tissue and extracellular matrices, such as Centella asiatica extracts, fractions of hyaluronic acids, alginates and chitosans;

- antioxidants, in particular plant polyphenols;

and mixtures thereof.

According to one particular embodiment, the process of the invention can comprise the steps consisting in:

(a) bringing the skin to be treated into contact with at least said nucleophilic agent and at least said agent with a pKa of greater than 11, for example by application of a composition comprising said agents; and

(b) bringing the skin to be treated into contact with one or more supplementary active agents, in particular by application of an additional composition comprising one or more supplementary active agents. These supplementary active agents can be used in said composition or compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11, and/or in an additional composition.

These supplementary active agents may be present in said composition or compositions in a content ranging from 0.001% to 20% by weight, preferably from 0.01% to 10% by weight and more particularly from 0.01% to 5% by weight, relative to the total weight of the composition.

Of course, a person skilled in the art will take care to choose the optional additional active agent or agents and/or their amount so that the advantageous properties of the combination of active agents according to the invention are not, or not substantially, detrimentally affected by the envisoned addition.

Of course, said composition or compositions of the invention can comprise any other adjuvant normal in the cosmetic field, such as hydrophilic or lipophilic gelling agents, hydrophilic or lipophilic active agents, preservatives, solvents, fragrances, fillers, screening agents, pigments, odor absorbers, sequestering agents and colorants. The amounts of these various adjuvants are those conventionally used in the field under consideration, for example from 0.01% to 20% of the total weight of the composition. In any event, these adjuvants and their proportions will be chosen so as not to harm the properties desired for the combination of active agents according to the invention.

Said composition or compositions according to the invention can be provided in any formulation form normally used in the cosmetic and dermatological fields.

They can be more or less fluid and can have the appearance of a liquid, a white or colored cream, an ointment, a milk, a lotion, a serum, a paste or a foam. It can optionally be applied to the skin in aerosol form. They can also be provided in solid form, in particular in stick form.

They can also be provided in the form of a patch, of a dressing or of an iontophoretic system.

Of course, it is up to a person skilled in the art to choose the appropriate formulation form and its method of preparation on the basis of his general knowledge, in particular from the viewpoint of the embodiment envisioned, according to the areas to be treated and according to whether the composition will be applied to the skin to be treated or injected into the thickness of the skin.

The examples which follow are presented by way of illustration and without implied limitation of the invention. EXAMPLES

Example 1

Caucasian skin is treated with a self-tanning product containing DHA at 7% by weight. Identical applications are made on four areas of the skin (100 mg of product for a surface area of 5 cm²).

After 4 hours, the four areas made up are colored and similar.

Makeup removal tests

The following day, the formulae A, B, C and D, the compositions of which are given in the following table 1, are applied to the four areas colored.

The percentages indicated in the following table are weight percentages.

Table 1

⁽¹⁾ sold by Ajinomoto,

⁽²⁾ sold by Nippon Rika,

^ sold by Palmer Company. Procedure

The guanidine is first of all dissolved in the water and then the cysteine derivative or the citric acid is added.

The solution obtained is transparent.

Ten minutes after application, the areas are rinsed with water and lightly rubbed with a paper tissue.

Results

A powerful makeup-removing effect is observed in the case of formulae C and D. Conversely, makeup is barely removed, or not removed at all, from the area treated with formulae A and B.

The liquid formulae according to the invention can also be applied with a brush, with a pen or with a marker pen so as to draw designs by hand, or with a negative stencil on a surface of the skin tinted with a formula comprising DHA, applied a few hours earlier.

A form of reverse tattoo is obtained, which can be personalised as required, which is discreet and which lasts for several days, independently of washing and bathing and with no risk of toxicity due to dyes.

If the design is no longer suitable, it is possible to erase the whole thing at leisure, by applying the formula according to the invention to the whole of the area.

Example 2

A first composition A is prepared, comprising:

N-acetyl-L-cysteine 8.25 g

Guanidine carbonate 8.75 g

Water q.s. 50 g

Then, a composition B is prepared, comprising:

5-(n-octanoyl)salicylic acid l -2 g

Isopropyl myristate 20 g

Sodium lauryl ether sulfate 10 g

Water q.s. 50 g The two compositions A and B are mixed together with mechanical stirring. Then, the mixture is applied to skin already colored with DHA. It is left on for 5 min. Then, rinsing is carried out while rubbing with a paper tissue.

A makeup-removing effect is observed.

Example 3

The following composition is prepared:

N-acetyl-L-cysteine

Guanidine carbonate

Pumice Stone Powder

(INCI=Pumice from CH.B. CRYSTAL)

Hydroxypropyl guar

(Jaguar HP 105 from Rhodia)

Water

The composition is heated at 50°C for 20 min, and is then left to cool.

The composition is then applied to skin treated with DHA while massaging the area with the finger tips. Rinsing is then carried out, followed by wiping with a paper tissue.

A makeup-removing effect is observed.

Claims

1. A cosmetic process for removing makeup from and/or cleansing the skin, which comprises at least bringing the skin into contact with at least one nucleophilic agent, said nucleophilic agent being a thiol derivative, and at least one nitrogen-comprising or phosphorus-comprising agent with a pKa of greater than 1 1 , distinct from said nucleophilic agent.

2. The process as claimed in claim 1 , said skin having been colored previously with carbonyl compounds.

3. The process as claimed in claim 1 or 2, wherein said nucleophilic agent is chosen in particular from:

- cysteine and its N-alkylated, N-acylated or C-alkylated derivatives; homocysteine and its N-alkylated, N-acylated or C-alkylated derivatives; or peptides comprising them, such as, for example, reduced glutathione;

- cysteamine and its N-alkylated or N-acylated derivatives;

- thioglycolic acid and its derivatives, thio lactic acid and its derivatives, mercaptopropionic acid and its derivatives.

4. The process as claimed in any one of the preceding claims, wherein said nucleophilic agent is chosen from cysteine and its N-alkylated, N-acylated or C-alkylated derivatives; homocysteine and its N-alkylated, N-acylated or C-alkylated derivatives; and peptides comprising them, such as, for example, reduced glutathione.

5. The process as claimed in any one of the preceding claims, wherein said agent with a pKa of greater than 11 is chosen from guanidine or one of its derivatives; imidazole or a compound comprising an imidazolyl group; or pyrrole or a compound comprising a pyrrolyl group.

6. The process as claimed in any one of the preceding claims, wherein said agent with a pKa of greater than 11 is chosen from guanidine and its derivatives.

7. The process as claimed in any one of the preceding claims, wherein said agent with a pKa of greater than 11 is the guanidinium ion, more particularly used in the form of guanidine carbonate, of guanidine hydroxide or of guanidine thiocyanate.

8. The process as claimed in any one of the preceding claims, wherein said nucleophilic agent is chosen from cysteine and its N-alkylated, N-acylated and C-alkylated derivatives, and said agent with a pKa of greater than 11 is guanidine or one of its derivatives.

9. The process as claimed in any one of the preceding claims, wherein said nucleophilic agent is N-acetyl-L-cysteine and said agent with a pKa of greater than 11 is the guanidinium ion, in particular in the form of guanidine carbonate.

10. The process as claimed in any one of the preceding claims, wherein said nucleophilic agent and said agent with a pKa of greater than 11 are used in a nucleophilic agent/agent with a pKa of greater than 11 molar ratio ranging from 10 to 1, in particular from 5 to 1 and more particularly of approximately 1.

11. The process as claimed in any one of the preceding claims, comprising at least the steps consisting in:

(i) bringing the skin into contact with a composition comprising at least said nucleophilic agent; and

(ii) bringing the skin into contact with a composition comprising at least said agent with a pKa of greater than 11 ;

12. The process as claimed in any one of claims 1 to 10, which comprises bringing the skin into contact with a composition comprising at least one nucleophilic agent and at least one agent with a pKa of greater than 11 , said composition being in particular obtained by extemporaneous mixing of at least one composition comprising said nucleophilic agent and of at least one composition comprising said agent with a pKa of greater than 11.

13. The process as claimed in any one of the preceding claims, characterized in that it comprises the application to and/or the injection into the thickness of the skin of one or more compositions comprising said nucleophilic agent and/or said agent with a pKa of greater than 11.

14. A kit for removing makeup from and/or cleansing the skin, comprising, in separate containers, at least one nucleophilic agent, said nucleophilic agent being a thiol derivative, and at least one nitrogen-comprising or phosphorus-comprising agent with a pKa of greater than 11, distinct from said nucleophilic agent, in particular as defined in any one of claims 3 to 10.

15. The kit as claimed in claim 14, additionally comprising at least one means for application to or injection into the thickness of the skin.