EP4262742A1

EP4262742A1 - Dye compositions comprising an extract of the aerial parts of sorghum bicolor (l.) moench

Info

Publication number: EP4262742A1
Application number: EP21851616.9A
Authority: EP
Inventors: Christel Fiorini-Puybaret; Philippe Joulia
Original assignee: Pierre Fabre Dermo Cosmetique SA
Current assignee: Pierre Fabre Dermo Cosmetique SA
Priority date: 2020-12-16
Filing date: 2021-12-16
Publication date: 2023-10-25
Also published as: FR3117370B1; WO2022129800A1; FR3117370A1

Abstract

The present invention relates to a method for preparing a dye composition, in particular a cosmetic dye composition for dyeing keratin fibres, and to the compositions obtained by such a method. The dye compositions comprise an extract of the aerial parts of Sorghum bicolor (L.) Moench and an extract of the aerial parts of Lawsonia inermis.

Description

DESCRIPTION

TITLE: COLORING COMPOSITIONS COMPRISING AN EXTRACT OF THE AERIAL PARTS OF SORGHUM BICOLOR (L.) MOENCH

FIELD OF THE INVENTION

The present invention relates to a method for preparing a coloring composition, in particular a coloring cosmetic composition for coloring keratin fibres, and to the compositions obtained by such a method. The coloring compositions comprise an extract of the aerial parts of Sorghum bicolor (L.) Moench and an extract of the aerial parts of Lawsonia inermis.

STATE OF THE ART

Cosmetic compositions intended for hair coloring do not escape the current trend of consumers seeking natural products. Plant-based hair colors are increasingly popular. These colors use dyes or pigments extracted from plants to color the hair. They are devoid of chemicals, of the oxidant or ammonia type, which can be aggressive for the hair. In order to offer a wide range of shades, different dye plant extracts can be used (henna, indigo, katam, chamomile, madder, etc.). Generally, vegetable colorings include a combination of different extracts and/or powders of dyeing plants, the dosage of which can be complex. Apart from the narrower choice of colors, plant hair dyes have a few other disadvantages. They are generally less resistant to shampoos than traditional chemical colorings and require long break times of up to two hours. Obtaining an even color, especially in the presence of white hair, may also require repeated applications. In an effort to meet consumer needs and broaden the choice of shades, efforts are continuing to develop new vegetable coloring compositions that effectively color keratin fibers and are easy to use.

Originating in Africa, red sorghum (Sorghum bicolor (L.) Moench is grown there from Senegal to Sudan in the form of several inedible types (cultivars or varieties) of common sorghum. These types are exclusively grown for the red dye content in the leaves and in the stem The traditional preparation of this dye is made from the stems and leaves by aqueous extraction or pressing to release the juice.

The active principles responsible for the coloring efficacy are anthocyanins rare in the plant kingdom, in particular derivatives of 3-deoxyanthocyanins, with a majority apigenidin and luteolinidin which represent 36 to 50% of the pigments (AWIKA JM - Properties of 3-Deoxyanthocyanins from Sorghum, J. Agric. Food Chem. 2004, 52, 4388-4394). In the plant, these anthocyanin substances are associated with tannins of the condensed type of proanthocyanidins (which produce red phlobaphenes). The red pigment of the leaf sheath of sorghum represents more than 20% of its dry weight.

Red Sorghum dye is traditionally used in Africa to color fabrics and other objects red (wool, yarn, ornamental gourds) and purple (masks). The use of red sorghum in hair coloring has also been proposed.

However, the use for hair coloring of coloring agents derived from red sorghum of the prior art (obtained by aqueous extraction or pressing to release the juice) gives unsatisfactory results. Indeed, the red coloring intensity obtained with these red Sorghum extracts is low.

A need remains for the provision of new cosmetic compositions for coloring keratin fibers which are easy to use and offer intense coloring, making it possible to effectively cover gray hair.

SUMMARY OF THE INVENTION

The present invention relates to a method for preparing a coloring composition, in particular a coloring cosmetic composition for coloring keratin fibres, comprising the following steps:

- supply of a first coloring agent, the first coloring agent comprising an extract of the aerial parts of Sorghum bicolor (L.) Moench comprising at least 2.5% by weight of apigeninidine relative to the total weight of the extract dry ;

- supply of a second coloring agent, the second coloring agent comprising an extract of the aerial parts of Lawsonia inermis comprising less than 0.6% by weight of lawsone and at least 10% by weight of phenolic compounds relative to the total weight dry extract;

- optional supply of one or more additional coloring agents from dyeing plants, microorganisms or microalgae, the additional coloring agent being different from the first and second coloring agents;

- mixing of the first and second coloring agents and additional coloring agents if present;

- Obtaining the coloring composition.

The present invention also relates to coloring compositions, in particular coloring cosmetic compositions for coloring keratin fibres, which can be obtained according to such a method. The present invention also relates to a cosmetic method for dyeing keratin fibers comprising the application to the keratin fibers of an aqueous composition comprising a dye composition as described herein.

Other aspects of the invention are as described below and in the claims.

DETAILED DESCRIPTION OF THE INVENTION

- supply of a first coloring agent, the first coloring agent comprising, or consisting of, an extract of the aerial parts of Sorghum bicolor (L.) Moench comprising at least 2.5% by weight of apigeninidine with respect to the weight total dry extract;

- provision of a second coloring agent, the second coloring agent comprising, or consisting of, an extract of the aerial parts of Lawsonia inermis comprising less than 0.6% by weight of lawsone and at least 10% by weight of phenolic compounds relative to the total weight of the dry extract;

- mixing of the first and second coloring agents and additional coloring agents if present; and

- Obtaining the coloring composition.

The expression "aerial parts" means the parts of the plant located above the ground, for example the leaves, the stems, the petioles, the flowers, the seeds and the branches, in particular the leaves, the stems and the seeds or a mixture of these.

The term "plant extract" means a product extracted from a plant, whether the whole plant, aerial parts, underground parts, flowers or fruits, including dried fruits. The extraction can consist of a simple pressing or involve the use of a solvent extraction.

The present invention is part of a desire to set up synthetic routes which are greener and which make it possible to claim the naturalness of the active principles thus obtained. Thus, the solvent(s) used in the context of the present invention will therefore preferably be natural solvents and/or solvents of natural origin derived from renewable resources, as opposed to fossil resources, these solvents possibly being advantageously obtained by processes eco-friendly. The extract from the invention will therefore preferably be a natural extract and/or of natural origin, derived from renewable resources, as opposed to fossil resources.

The present invention also relates to the coloring compositions, in particular the coloring cosmetic compositions for coloring keratin fibres, obtained by the method of the present invention.

The expression “keratin fibres” designates the keratin present in the epidermis and the appendages, such as the skin, the hair, the body hair, the eyelashes, the eyebrows, more particularly the hair.

The coloring cosmetic compositions according to the invention have the advantage of intensely coloring the keratin fibres, in particular the hair, using coloring agents derived from plants without altering the keratin fibers and of having good resistance to washing, including after 10 or 15 washes of the keratin fibres. Advantageously, colors of a beautiful intensity are obtained with a limited number of dyes derived from plants (typically less than five) thus limiting the risk of allergies. Furthermore, the cosmetic compositions according to the present invention make it possible to color keratin fibers quickly and easily. Typically, the time devoted to coloring is less than two hours or even less than one hour and thirty minutes and only one application is necessary. They offer good coverage of white hair and allow obtaining a homogeneous coloring.

The dye compositions according to the present invention are preferably in powder form (in dry form). A powder according to the invention is a solid product in the form of particles. Typically, the average particle size of the powders is less than 250 μm. The average particle size of the powders can be between 0.1 μm and 250 μm, particularly between 1 μm and 250 μm. These fine particles can be obtained by grinding. The grinding can be carried out by any suitable means allowing a reduction in size and the obtaining of fine particles as mentioned above. Advantageously, a powder according to the invention is a dry and pulverulent product whose humidity level is negligible. A powder according to the invention is thus water-soluble or easily water-dispersible, that is to say it can be used to obtain an aqueous or hydroalcoholic liquid composition containing 20 to 60% by weight of dry matter, more particularly between 30 and 50% by weight of dry matter and more particularly still about 40% by weight of dry matter. The dry matter thus represents the powder.

The first and second coloring agents and any additional coloring agents entering into the formulation of the coloring compositions, in particular colorings cosmetic dyes for dyeing keratin fibres, are as described below.

The percentages by weight given below refer to the total weight of the dry extract considered, unless explicitly stated otherwise. The percentages by weight expressed in relation to "the total weight of the dry extract" refer to an extract devoid of extraction solvent or support, or containing only an insignificant trace. Such a dry extract thus contains only material derived from the plant. The percentages by weight expressed in relation to "the total weight of the dry standardized extract" refer to a standardized extract devoid of extraction solvent, or containing only insignificant trace amounts.

Extract of aerial parts of Sorghum bicolor (Sorghum bicolor (L.) Moench)

The active principles, present in the plant, responsible for the red coloring efficiency are polyphenols of the class of anthocyanins rare in the plant kingdom, in particular derivatives of 3-deoxyanthocyanins but also polyphenols of the class of condensed tannins of proanthocyanidins which polymerize into brown dyes (red phlobaphenes).

The extract of the aerial parts of Sorghum bicolor (L.) Moench useful in the context of the present invention, referred to below as "extract of Sorghum bicolor, is characterized by a high content of 3-deoxyanthocyanin derivatives (subfamily of anthocyanidins), especially apigenidin. It generally includes luteolinidin in lower levels. 3-deoxyanthocyanins have a strong antioxidant power (AWIKA J.M. - Properties of 3-Deoxyanthocyanins from Sorghum, J. Agric. Food Chem. 2004, 52, 4388-4394). Thus, the extract of Sorghum bicolor useful in the context of the present invention comprises at least 2.5% by weight of apigeninidine, typically from 3 to 10% or from 5 to 7% by weight of apigeninidine with respect to the weight total dry extract.

The apigeninidine content of the extracts of Sorghum bicolor can in particular be determined according to the C.L.H.P assay method at 474 nm as described in the experimental section (Method 1).

In addition to this high content of apigenidin, the extract of Sorghum bicolor can be characterized more generally by a high content of polyphenols, quite particularly of red dyes of the class of polyphenols, more specifically by a high content of anthocyanins in the form free or glycosylated. The content of anthocyanins in free or glycosylated form of the extract of Sorghum bicolor from aerial parts thus typically varies from 5 to 50% by weight, preferably from 10 to 50% by weight relative to the total weight of the dry extract. . The anthocyanin assay method is that described among others in the European Pharmacopoeia 01/2019:1602. Within these anthocyanins in free or glycosylated form, the 3-anthocyanins are very particularly present in the extract of Sorghum bicolor, in particular the 3-deoxyanthocyanidins which include apigenidin and luteolinidin.

The extract of Sorghum bicolor useful in the context of the present invention can also be characterized by a low content of water-soluble compounds, this content of water-soluble compounds varying from 0 to 10% by weight or even from 0 to 5% by weight with respect to the total weight of dry extract. These water-soluble compounds are devoid of coloring activity on the keratin fibres, and can also inhibit the binding of the compounds responsible for the coloring on the keratin fibres. The water-soluble compounds most particularly comprise sugars (total sugars: from 20 to 60% by weight of the water-soluble compounds, typically around 40% by weight) and proteins (from 1 to 10% by weight of the water-soluble compounds, typically around 3% by weight). weight).

The coloring intensity (CI) of the Sorghum bicolor extract useful in the context of the present invention generally varies from 90 to 200, in particular from 100 to 200. The coloring intensity can be determined according to method 2.

In some embodiments, the Sorghum bicolor extract is mixed with an inert carrier. The first coloring agent then comprises the extract of Sorghum bicolor and an inert support. The inert support may be as described below. Typically, the mixture of an extract of Sorghum bicolor and an inert support leads to a standardized extract of Sorghum bicolor. The expression "standardized extract" designates an extract having a chosen content of at least one of the coloring compounds of the plant extract and/or a given range of coloring intensity. It is usually obtained by adding an inert carrier to the herbal extract in varying amounts depending on the variability from batch to batch of plants, if any.

The standardized extract of Sorghum bicolor typically consists of 10 to 30% by weight of a carrier and 70 to 90% by weight of the dry extract of Sorghum bicolor relative to the weight of the standardized dry extract of Sorghum bicolor . In certain embodiments, the standardized extract of Sorghum bicolor consists of 20% by weight of a carrier and 80% by weight of the dry extract of Sorghum bicolor.

The standardized extract of Sorghum bicolor generally comprises, relative to the total weight of standardized dry extract, from 2.4% to 8% by weight of apigeninidine, typically about 5% by weight.

The standardized extract of Sorghum bicolor generally comprises, relative to the total weight of standardized dry extract, from 4 to 16% by weight of anthocyanins in free or glycosylated form. The standardized extract of Sorghum bicolor generally also includes, relative to the total weight of standardized dry extract:

- from 2.4% to 8% by weight of apigeninidine, typically about 5% by weight;

- from 0 to 10% by weight of water-soluble compounds, typically around 6% by weight, the water-soluble compounds comprising from 20 to 60% by weight of sugars, typically around 40% by weight of sugar, and from 1 to 10% by weight protein, typically 3% by weight protein.

The coloring intensity of the standardized extract of Sorghum bicolor generally varies from 90 to 200, in particular from 100 to 200 (method 2).

The Sorghum bicolor extract can be obtained by solid/liquid extraction of the aerial parts of Sorghum bicolor, using an organic solvent chosen from alcohols (miscible or immiscible in water), esters, ketones, ethers, chlorinated solvents or mixtures thereof or by means of a hydroalcoholic solution comprising at least 50%, at least 60%, at least 70%, at least 80% or even at least 90% by volume of an alcohol miscible in the 'water.

The water-miscible alcohol can be chosen from linear or branched alcohols comprising from one to six carbon atoms. Examples of water-miscible alcohols include methanol, ethanol, and ter-butanol. Preferably, the water-miscible alcohol is ethanol.

In certain embodiments, the organic solvent is chosen from methanol, ethanol, n-amyl alcohol, ter-butanol, n-butanol, sec-butanol, iso-butanol, dichloromethane, chloroform, methyl isobutyl ketone, diethyl ether, diisopropyl ether, dibutyl ether, methyl tert-butyl ether, (C-i-Ce-alkyl) acetates, such as ethyl acetate, acetate isopropyl, butyl acetate and isoamyl acetate, and mixtures thereof. In some embodiments, the organic solvent is ethanol.

In certain embodiments, the solid/liquid extraction is carried out using a hydroalcoholic solution comprising at least 70%, at least 80% or even at least 90% by volume of a water-miscible alcohol. The water-miscible alcohol is preferably ethanol.

In certain embodiments, the solid/liquid extraction is carried out using an alcohol, preferably ethanol, having an alcoholic strength varying from 50 to 100, or from 60 to 100, or from 70 to 100, or 80 to 100 or 90 to 100 degrees.

The aerial parts of Sorghum bicolor can be leaves, stems and/or seeds, preferably stems and leaves, fresh or dried, preferably dried, or mixtures thereof. The aerial parts of Sorghum bicolor are preferably finely ground. The solid/liquid extraction comprises a phase of bringing the aerial parts of Sorghum bicolor into contact with the extraction solvent, preferably an alcohol, or with the hydroalcoholic solution.

This contacting step can be carried out according to known methods. The contacting can be a maceration (contacting phase maintained at a temperature below the boiling temperature of the extraction solution), a decoction (contacting phase maintained at the boiling temperature of the solution extraction) or leaching (the extraction solution passes through the biomass).

The extraction can be assisted by extraction aids, such as high pressure (supercritical CO2), microwaves or ultrasound.

The duration of contacting can vary from 30 minutes to 4 hours, or from 1 hour to 3 hours, generally it is 2 hours.

In certain embodiments, the extraction can be carried out at ambient temperature (20-25° C.) or hot, for example at temperatures which can vary from 25° C. to 180° C., at atmospheric or supercritical pressure, with or without agitation.

At the end of the contacting time, a liquid/solid separation is carried out. The separation can be carried out by any liquid-solid separation technique known to those skilled in the art, such as filtration, centrifugation or decantation. The liquid phase is collected, optionally sterilized by conventional sterilization methods (pasteurization, flash pasteurization, etc.) then concentrated and optionally dried by conventional methods (paddle dryer, vacuum drying, atomization, lyophilization, zeodration, microwaves , etc.) to give an extract of Sorghum bicolor useful in the context of the present invention. As described in more detail below, a carrier can be added after concentration and before possible drying of the extract or after the possible drying step.

More specifically, the extraction can be carried out by a process comprising the following steps: a) agitation of the aerial parts of Sorghum bicolor in an organic solvent chosen from alcohols, esters, ketones, ethers, chlorinated solvents or mixtures thereof or in a hydroalcoholic solution comprising at least 50%, at least 60%, at least 70%, at least 80% or even at least 90% by volume of an alcohol miscible in water, preferably in ethanol or in a hydroalcoholic solution comprising at least 70%, at least 80% or even at least 90% by volume of ethanol; b) liquid/solid separation; c) recovery of the liquid phase; d) concentration of the liquid phase obtained in step c) and elimination of the alcohol; e) possibly drying.

In certain embodiments, the agitation is carried out at a temperature ranging from 20° C. to 25° C. for 1 to 4 hours, preferably 2 hours.

In certain embodiments, the extraction is carried out in a ratio (m/v) aerial parts of Sorghum b/co/gold/hydroalcoholic solution ranging from 1/10 to 1/30, typically 1/20.

In certain embodiments, the method may comprise a step of adding a support at the end of step d). The step of adding a support is then preferably followed by a drying step. The addition of a support at the end of step d) can make it possible to standardize the content of at least one of the coloring compounds of the plant extract. Thus, the content of at least one of the coloring compounds of the plant extract can be fixed by varying the amount of support so as to take into account the variability from one batch of plants to another. A standardized extract, dry or not, of Sorghum bicolor is then obtained.

The support must be inert with respect to the extract and its components: it does not interact with the extract or its components, contributes to its protection and makes it possible to standardize the final content of active extract. The support is preferably a natural support and/or of natural origin derived from renewable resources, as opposed to fossil resources, these supports being moreover obtained by methods that respect the environment.

The carrier must be "cosmetically acceptable", which means that it is generally safe, non-toxic and neither biologically nor otherwise undesirable and that it is acceptable for cosmetic use, in particular by topical application, in particular by topical application on the keratinous fibres, in particular the hair and the scalp. It is typically selected from protein-free carriers.

The support can in particular be chosen from propanediol, pentanediol, glycerin, propylene glycol, methyl THF and amyl alcohol.

Preferably, when the cosmetic composition is in powder form, the carrier is chosen from sugars and polysaccharide derivatives, such as fructose, glucose, sucrose, maltodextrins, cellulose derivatives, starch, in particular corn starch, wheat starch, rice starch, agar-agar, gums, mucilages, polyols such as mannitol, sorbitol, xylitol, etc. The support is in particular chosen from fructose, maltodextrins and starch, in particular rice starch. Preferably, the carrier is maltodextrin.

Drying can be carried out by conventional methods (paddle dryer, vacuum drying, atomization, freeze-drying, zeodration, microwaves, etc.).

The Sorghum bicolor extract can be ground to give a homogeneous powder, in particular with a particle size of less than 250 μm. The extract of Sorghum bicolor obtained by such a process is characterized by a high content of apigeninidine, that is to say that it comprises at least 2.5% by weight of apigeninidine, typically from 3 to 10% or from 5 to 7% by weight of apigeninidine relative to the total weight of the dry extract.

If the exact qualitative and quantitative compositions of an extract of Sorghum bicolor obtained by such a process cannot be reasonably determined, the extract of Sorghum bicolor may be characterized more generally by a high content of polyphenols, especially red pigments from the class of polyphenols, more specifically by a high content of anthocyanins in free or glycosylated form. The content of anthocyanins in free or glycosylated form of the extract of Sorghum bicolor obtained by such a process thus typically varies from 5 to 50% by weight, preferably from 10 to 50% by weight relative to the total weight of the extract. dry. Within these anthocyanins in free or glycosylated form, 3-anthocyanins are particularly present, in particular 3-deoxyanthocyanidins which include apigenidin and luteolinidin.

The Sorghum bicolor extract obtained by such a process is also characterized by a low sugar (total sugar) and protein content.

Typically, the Sorghum bicolor extract obtained by such a process, in particular when the extraction is carried out using an alcohol or a hydroalcoholic solution, comprises from 0 to 10% by weight or from 0 to 7% by weight of compounds not soluble in the alcohol used in the extraction process relative to the total weight of the dry extract. Compounds that are not soluble in alcohol, especially in ethanol, also called water-soluble compounds, include very particularly sugars (total sugars: from 20 to 60% by weight of compounds that are not soluble in alcohol) and proteins ( from 1 to 10% by weight of the compounds not soluble in alcohol).

Typically, the “compounds not soluble in alcohol/compounds soluble in alcohol” weight ratio varies from 0 to 1, or from 0 to 0.5. It is usually 0.5. The extract of Sorghum bicolor obtained by such a process can be a standardized extract of Sorghum bicolor.

The extract of Sorghum bicolor obtained by such a process offers a more intense red coloring efficiency (coloring intensity > 90, preferably > 100) than currently available commercial extracts which give unsatisfactory results because of their too weak coloring intensity whatever are the concentrations tested.

A significantly improved coloring efficacy on locks of hair and above all dose-dependent was observed with the Sorghum bicolor extract alone according to the present invention, unlike a Sorghum extract of the prior art.

This result makes it possible to consider new uses for such a coloring agent, alone or in combination with other coloring agents, depending on the desired shade. The extraction of the aerial parts of Sorghum bicolor using an organic solvent as described above or a hydroalcoholic solution as described above allows the elimination of compounds that can inhibit the fixing of the compounds responsible for the coloration on keratin fibres. In particular, the extract of Sorghum bicolor obtained by such a process in combination with one or more coloring agents derived from dyeing plants, microorganisms or microalgae makes it possible to obtain blonde, coppery, chestnut preferably beautiful dark chestnut colors or mahogany type reflections. Advantageously, the extract of Sorghum bicolor obtained by such a process makes it possible to modulate the effects of the coloring, a dose-dependent coloring efficacy being able to be observed with such extracts, unlike the commercial extracts currently available.

The Sorghum bicolor extract obtained by such a process offers good stability. It is not necessary to add acid-type preservatives. In certain embodiments, an acid can nevertheless be added to any of the steps of the process, for example the liquid phase obtained in step c) can be acidified or the acidification can be carried out at the time of drying.

Furthermore, an improvement in the adhesion of the coloring was observed when the extract of Sorghum bicolor is used in combination with an extract of the aerial parts of Lawsonia inermis, in particular in combination with an extract of the aerial parts of Lawsonia inermis rich in lawsone and/or an extract of the aerial parts of Lawsonia inermis low in lawsone as described below.

It will be easily understood that the solid/liquid extraction process using an organic solvent or an aqueous-alcoholic solution comprising at least 50%, at least 60%, at least 70%, at least 80% or even at least 90 % by volume of an alcohol miscible in water, presently described, can be implemented on other dye cultivars of sorghum, such as dye cultivars which are inedible or cannot be used in cosmetics, leading to the preparation of enriched extracts in red dyes. Such extracts can be used in many technical fields. For example, they can be used to color textiles, furniture, textile fibers, wood fibers or to prepare inks (eg for paper or cardboard).

Thus, in one aspect, the present invention relates to the use of an extract of the aerial parts of Sorghum bicolor (L.) Moench or one of its dye cultivars comprising at least 2.5% by weight of apigenidin per relative to the total weight of the dry extract which can be obtained by solid/liquid extraction, by means of an organic solvent chosen from alcohols, esters, ketones, ethers, chlorinated solvents or their mixtures or by means of a hydroalcoholic solution comprising at least 50%, at least 60%, at least 70%, at least 80% or even at least 90% by volume of a water-miscible alcohol, aerial parts of Sorghum bicolor (L.) Moench or one of its dye cultivars for coloring keratin fibres, textiles, furniture, textile fibres, wood fibers or for preparing inks (for example for tattooing, paper or cardboard) .

Extract of aerial parts of Lawsonia inermis

The extract of the aerial parts of Lawsonia inermis useful in the context of the present invention, referred to below as "Extract of Lawsonia inermis", is characterized by a low content of lawsone. Lawsone (2-hydroxy-1,4-naphthoquinone) is the dye molecule responsible for the coloration typically obtained when powders or extracts of Lawsonia inermis are used to dye keratin fibres. In the context of the present invention, the extract of Lawsonia inermis is not used for coloring purposes - due to its low content of lawsone - but for its ability to improve the grip of the extract of aerial parts of Sorghum bicolor and/or any coloring agents entering into the formulation of the coloring hair compositions of the present invention.

Thus, Lawsonia inermis extract comprises less than 0.6%, less than 0.5%, or less than 0.4% by weight, of lawsone relative to the total weight of the dry extract. In some embodiments, the Lawsonia inermis extract comprises 0 to 0.6%, or 0.05 to 0.6%, or 0.1 to 0.5%, or 0.1 to 0 .4% by weight of lawsone relative to the total weight of the dry extract. In some embodiments, the Lawsonia inermis extract comprises about 0.2% by weight of lawsone based on the total weight of the dry extract.

The lawsone content of Lawsonia inermis extracts can in particular be determined according to the C.L.H.P assay method described in the experimental section (Method 3).

The Lawsonia inermis extract useful in the context of the present invention comprises at least 10% or at least 15% by weight of phenolic compounds relative to the total weight of the dry extract. Typically Lawsonia inermis extract comprises 10-50% or 10-35% or 15-35% or 15%-30% by weight of phenolic compounds relative to the total weight of the dry extract. The contents of phenolic compounds are expressed by reference to the pyrogallol content (method 4).

The term "phenolic compounds" designates more particularly phenolic acids (eg gallic acid and the heterosides of such compounds), cinnamic acids (eg coumaric acid and the glycosides of such compounds), tannins (eg hydrolysable tannins, more particularly gallic tannins), phloroglucinol derivatives (eg 2,3,4,6-tetrahydroxyacetophenone, 1,3,6,7 tetrahydroxyxanthone, phloroacetophenone, myrciaphenone A, lalioside, and glycosides of such derivatives such as polygoacetophenoside), napthoquinone derivatives (e.g. isonapthazarine and glycosides of such derivatives such as 1,2,4-trihydroxynaphthalen-1-O-glucoside) and flavonoids (apigenin, luteolin, and/or glycosides of such derivatives such as luteolin-4'-O-glucoside, luteolin-7-O-glucoside ).

In particular, the Lawsonia inermis extract useful in the context of the present invention can be characterized by the presence of the following phenolic compounds:

- tannins, in particular hydrolysable tannins, more particularly gallic tannins;

- gallic acid;

- luteolin and its heterosides, in particular its glycosylated derivatives;

- apigenin;

- 2, 3, 4, 6 - tetrahydroxyacetophenone;

- 1, 3, 6, 7 - tetrahydroxyxanthone.

The method for assaying the phenolic compounds (method 4) has particularly made it possible to demonstrate that the extract of Lawsonia inermis comprises the following phenolic compounds in the amounts indicated, relative to the total weight of the dry extract:

- from 0.05 to 2.5%, in particular 0.05 to 0.5%, more particularly from 0.1 to 0.3%, by weight of luteolin;

- from 0.01 to 3.75%, in particular 0.01 to 0.75%, more particularly from 0.05 to 0.5%, by weight of apigenin;

- from 0.01 to 2.5%, in particular 0.01 to 0.5%, more particularly from 0.02 to 0.1%, by weight of 2, 3, 4, 6 - tetrahydroxyacetophenone;

- from 0.05 to 2.5%, in particular 0.05 to 0.5%, more particularly from 0.1 to 0.3% by weight of gallic acid.

In certain embodiments, the Lawsonia inermis extract useful in the context of the present invention comprises a high content of saccharide compounds. Thus, the Lawsonia inermis extract may comprise at least 60% by weight, preferably at least 65% by weight or at least 70% by weight of saccharide compounds relative to the total weight of the dry extract. In certain embodiments, the Lawsonia inermis extract comprises 60 to 80% by weight or 70 to 75% by weight of saccharide compounds relative to the total weight of the dry extract.

The term "saccharide compounds" refers to monosaccharides, disaccharides and polysaccharides (eg mucilage).

Typically, the polysaccharides are in the majority by weight, that is to say they constitute more than 50%, more than 60%, more than 70%, more than 80% or more than 90% by weight, of the total weight in saccharide compounds present in the extract.

The extract of Lawsonia inermis can be characterized quite particularly by the presence of mucilages. Mucilages are plant substances, made up of polysaccharides, or also proteosaccharides, which swell on contact with water, taking on a viscous, sometimes sticky, gelatin-like consistency. Mucilages correspond to compounds with large, more or less branched polymeric structures constructed from several different osidic or uronic acid units (uronic acids are carboxylic acids derived from sugars). They are very hydrophilic and are able to trap water (and other molecules) in their cage-like structures to form a gel. Mucilages can be particularly beneficial for keratin fibers by contributing to their hydration.

The content of saccharide compounds in Lawsonia inermis extracts can be determined by dinitrosalicylic colorimetric assay (Method 5).

In certain embodiments, the second coloring agent is an extract of the aerial parts of Lawsonia inermis comprising less than 0.6% by weight of lawsone, at least 10% by weight of phenolic compounds and at least 60% by weight of compounds saccharides relative to the total weight of the dry extract.

The Lawsonia inermis extract useful in the context of the present invention may also comprise at least 2%, at least 3% or at least 4% by weight of organic acids relative to the total weight of the dry extract. In certain embodiments, the Lawsonia inermis extract comprises 2 to 8% or 4 to 8% by weight of organic acids based on the total weight of the dry extract.

The organic acids of the Lawsonia inermis extract include in particular hydroxy acids, that is to say hydrocarbon compounds bearing at least one carboxylic acid function -COOH and at least one alcohol function -OH, advantageously at least one alcohol function is in position alpha of a carboxylic acid function (that is to say carried by a carbon atom adjacent to the carbon atom carrying the carboxylic acid function). The organic acids of the extract of Lawsonia inermis are advantageously carboxylic acids whose linear alkyl chain, branched or comprising a cycle, comprises from 4 to 8 or from 4 to 6 carbon atoms. The carboxylic acids of Lawsonia inermis extract especially include succinic acid, ascorbic acid, malic acid and combinations thereof.

Organic acids, such as malic acid, succinic acid and ascorbic acid, can be assayed by enzymatic or spectrophotometric methods known and available to those skilled in the art, in particular by C.L.H.P (Method 8).

These organic acids can contribute to reinforcing the adhesion of the components of the Sorghum bicolor extract to the keratin fibre. They can also contribute to enhancing the shine of the hair thus colored and to hydrating the keratin fibres. The Lawsonia inermis extract useful in the context of the present invention may also comprise lactones, in an amount generally less than 10% by weight.

The Lawsonia inermis extract useful in the context of the present invention may also comprise compounds of protein nature, such as peptides, amino acids and proteins, in an amount ranging from 5 to 10% by weight relative to the total weight of the dry extract.

The Lawsonia inermis extract useful in the context of the present invention can be characterized in that it comprises one or other of the following compounds, or even all of them (content expressed relative to the total weight of the extract dry) :

- gallic acid, typically at a content ranging from 0.05 to 0.5%, more particularly from 0.1 to 0.3% by weight;

- 2,3,4,6-tetrahydroxyacetophenone, typically at a content ranging from 0.01 to 0.5%, more particularly from 0.02 to 0.1%, by weight;

- luteolin, from 0.05 to 0.5%, more particularly from 0.1 to 0.3% by weight;

- apigenin, typically at a content ranging from 0.01 to 0.75%, more particularly from 0.05 to 0.5%, by weight;

- 1,3,6,7-tetrahydroxyxanthone;

- 2 to 8% by weight of organic acids, including malic acid, succinic acid and ascorbic acid.

The Lawsonia inermis extract useful in the context of the present invention can be characterized by the following composition (content expressed relative to the total weight of the dry extract):

- less than 0.6%, less than 0.5% or less than 0.4% by weight of lawsone, for example from 0 to 0.6% by weight of lawsone;

- at least 10% by weight of phenolic compounds including:

- from 0.05 to 0.5% or from 0.1 to 0.3%, by weight of luteolin;

- from 0.01 to 0.75% or from 0.05 to 0.5%, by weight of apigenin;

- from 0.01 to 0.5% or from 0.02 to 0.1%, by weight of 2, 3, 4, 6 - tetrahydroxyacetophenone;

- from 0.05 to 0.5% or from 0.1 to 0.3% by weight of gallic acid;

- 1,3,6,7-tetrahydroxyxanthone;

- at least 60%, at least 65% or at least 70% by weight of saccharide compounds, for example from 60 to 80% by weight or from 70 to 75% by weight of saccharide compounds, of which mainly by weight polysaccharides such as mucilage; and

- from 2 to 8% or from 4 to 8% by weight of organic acids, including malic acid, succinic acid and ascorbic acid. In certain embodiments, the Lawsonia inermis extract may be in the form of a dry extract, advantageously in the form of a powder, in particular with a particle size of less than 250 μm

Lawsonia inermis extract can be obtained by aqueous, hydroalcoholic or alcoholic extraction.

In certain embodiments, the Lawsonia inermis extract can be obtained by aqueous or hydroalcoholic extraction of the aerial parts of Lawsonia inermis. The aerial parts of Lawsonia inermis can be fresh or dry, preferably dry leaves, twigs or mixtures thereof. The aerial parts of Lawsonia inermis are preferably finely ground.

The extraction can be carried out at room temperature (20-25°C) or hot, for example at temperatures which can vary from 25°C to 180°C, at atmospheric or supercritical pressure. Typically, the extraction is carried out by shaking the ground aerial parts of Lawsonia inermis in the extraction solution for a period varying from 15 minutes to 2 hours, or from 15 minutes to 1 hour, generally for 30 minutes.

The extraction includes a phase of bringing the aerial parts of Lawsonia inermis into contact with the extraction solution. The contacting can be a maceration (contacting phase maintained at a temperature below the boiling temperature of the solvent), a decoction (contacting phase maintained at the boiling temperature of the solvent) or leaching ( the solvent passes through the biomass). The extraction can be assisted by extraction aids, such as high pressure (supercritical CO2), microwaves or ultrasound.

The extraction solution can be water or a hydroalcoholic solution comprising a water-miscible alcohol, such as ethanol or ter-butanol. The hydroalcoholic solution typically comprises 30 to 90% v/v alcohol or 50 to 80% v/v alcohol. In addition to facilitating the extraction of hydrophilic compounds, alcohol, such as ethanol, also makes it possible to disinfect and decontaminate the mixture. When the extraction is carried out using water alone, a decontamination and/or sterilization step can be carried out, for example by heating with the injection of steam or by microwave treatment.

At the end of the extraction time, a liquid/solid separation is carried out. The separation can be carried out by any liquid-solid separation technique known to those skilled in the art, such as filtration, centrifugation or decantation. The liquid phase is collected, sterilized by conventional sterilization methods (pasteurization, flash pasteurization, etc.) then concentrated and possibly dried by conventional methods (paddle dryer, vacuum drying, atomization, lyophilization, zeodration, microwaves, etc.) to give an extract of Lawsonia inermis useful in the context of the present invention. More specifically, in certain embodiments, the extract of aerial parts of Lawsonia inermis can be obtained by an extraction process comprising the following steps: a) agitation of the aerial parts (e.g. crushed leaves) of Lawsonia inermis in a solution extraction (water or hydroalcoholic solution), typically in a ratio (m/v) aerial parts of Lawsonia/nerm/s/extraction solution ranging from 1/2 to 1/10, preferably from 1/4 to 1 /8, at a temperature ranging from 30° C. to 50° C.; b) liquid/solid separation; c) recovery of the liquid phase; d) concentration of the liquid phase obtained in step c); e) possibly drying; to obtain an extract of Lawsonia inermis.

In some embodiments, a pectinase-like enzyme may be added during step a).

If the exact qualitative and quantitative compositions of an extract of Lawsonia inermis obtained by such a process cannot be reasonably determined, the extract is nevertheless characterized by a low content of lawsone (less than 0.6%, less than 0.5 %, or less than 0.4% by weight lawsone). In certain embodiments, the Lawsonia inermis extract comprises from 0 to 0.6% or from 0.05 to 0.6%, or from 0.1 to 0.5%, or from 0.1 to 0, 4%, typically about 0.2% by weight, of lawsone relative to the total weight of the dry extract. The Lawsonia inermis extract obtained by such a process has the characteristics described above.

In other embodiments, the Lawsonia inermis extract can be obtained by a process comprising the following steps: a) maceration of the aerial parts of Lawsonia inermis in water, carried out at a pH of between 4 and 8, during which the glycosylated derivatives of lawsone, such as the hennosides, initially present in the aerial parts of Lawsonia inermis are partially or totally hydrolyzed enzymatically, resulting in the production of an aqueous solution containing lawsone; b) addition of an organic solvent to the aqueous solution obtained at the end of step a), the organic solvent being chosen from linear or branched C4-C12 alcohols and solvents whose miscibility in water is less than 10%, or even less than 5% by weight at 25° C., resulting in the formation of an aqueous phase and an organic phase; c) recovery of the aqueous phase obtained at the end of step b); and d) concentration of the aqueous phase recovered at the end of step c); e) possibly drying; to give Lawsonia inermis extract.

The aerial parts of Lawsonia inermis subjected to maceration can be fresh or dry, preferably dry leaves, twigs or mixtures thereof. The aerial parts of Lawsonia inermis are preferably finely ground.

Maceration is typically carried out by placing the aerial parts of Lawsonia inermis under agitation in a volume of water 2 to 15, or 5 to 15, or 6 to 10 times greater, typically 10 times greater, than the weight of the aerial parts of Lawsonia inermis for a period generally varying from 15 minutes to 2 hours or from 15 minutes and 1 hour, preferably for about 30 minutes. For example, when the process is implemented on 100 g of aerial parts of Lawsonia inermis, the volume of water used varies from 200 mL to 1500 mL, or from 500 mL to 1500 mL or from 600 to 1000 mL. During maceration, a pectinase type enzyme can be added.

The maceration is preferably carried out at a temperature ranging from 20 to 60°C or from 20 to 50°C or from 25 to 45°C or from 35 to 45°C. The temperature is typically 40°C.

The maceration is carried out at a pH allowing the functioning of the enzymes catalyzing the hydrolysis of the glycosylated derivatives of lawsone. The pH can vary from 5 to 7.5 or from 5.5 to 7.5 or from 6.5 to 7.5. The pH is typically around 7. It should be noted that the process does not include any step consisting in varying the pH of the aqueous solution or of the aqueous phase by adding acid or base.

At the end of the maceration time, filtration can be carried out to separate the aerial parts of Lawsonia inermis from the aqueous solution containing lawsone or the organic solvent can be added directly to the aqueous solution obtained. In this case, the filtration is carried out before the recovery of the aqueous phase.

The volume of organic solvent added is such that the organic solvent/water volume ratio varies from 0.25 to 2 or from 0.5 to 2 or from 0.8 to 1.5 or from 1 to 1.3.

In certain embodiments, the organic solvent is a linear or branched C4-C8 alcohol, for example n-butanol, sec-butanol, iso-butanol, and mixtures thereof. Preferably, the organic solvent is n-butanol.

In other embodiments, the organic solvent is chosen from C1-Ce alcohols, chlorinated solvents, ketones, ethers, esters and their mixtures which satisfy the following criteria:

- the miscibility of water in the organic solvent is less than 10%, or even 5% by weight at 25°C, - the miscibility of the organic solvent in water is less than 10%, or even 5% by weight at 25°C.

Examples of such solvents include n-amyl alcohol, dichloromethane, chloroform, methyl isobutyl ketone, diethyl ether, diisopropyl ether, dibutyl ether, methyl tert-butyl ether, (Ci-Cs)alkyl acetates , such as ethyl acetate, isopropyl acetate, butyl acetate and isoamyl acetate, and mixtures thereof. Preferably, the organic solvent is a (Ci-C6)alkyl acetate or a mixture of (Ci-Ce)alkyl acetates, preferably ethyl acetate, isopropyl acetate, butyl, isoamyl acetate or mixtures thereof. Particularly preferably, it is isopropyl acetate.

After addition of the organic solvent, the whole is stirred for a period ranging from 15 minutes to 2 hours or from 15 minutes to 1 hour. Typically, the whole is stirred for 30 minutes.

At the end of the stirring time, the whole is left to settle until two distinct phases are obtained, namely an aqueous phase and an organic phase.

The aqueous phase is then recovered and concentrated to give an extract of Lawsonia inermis low in lawsone.

The Lawsonia inermis extract obtained can be dried by conventional methods (e.g. paddle dryer, vacuum drying, atomization, microwave, zeodration or lyophilization).

The method may further comprise a decontamination and/or sterilization step between steps c) and d). The decontamination and/or sterilization step can be carried out, for example by heating with the injection of steam or by microwave treatment.

Coloring agents

The additional coloring agents which can enter into the formulation of the coloring compositions, in particular the coloring cosmetic compositions, of the present invention include the coloring agents derived from dyeing plants, from microorganisms or from microalgae. Preferably, the coloring agent is in dry form, advantageously in powder form, in particular with a particle size of less than 250 μm.

More particularly, the coloring agent can be a powder of dyeing plants or an extract of dyeing plants. A tinctorial plant powder differs from a tinctorial plant extract in that the plant powder is obtained by mechanical grinding of the whole plant, the aerial parts, the underground parts, the flowers or the fruits. The extract is most often an aqueous extract or a hydroalcoholic or alcoholic extract. It is understood that when the coloring agent is an extract of tinctorial plants, this plant extract is different from the extracts of Sorghum bicolore and Lawsonia inermis described above. The coloring agent may be a powder or a plant extract chosen from Lawsonia inermis, indigo plants, plants which are sources of red pigment, plants which are sources of red or violet to black pigment, plants which are sources of yellow pigment, plants red to bluish green pigment sources, tannin source plants, brown pigment source plants and combinations thereof.

When the coloring agent is an extract of Lawsonia inermis, the extract is different from the extract of Lawsonia inermis (poor in lawsone) described above. The extract is then characterized by a high content of lawsone. Thus, the Lawsonia inermis extract which can be combined with the first and the second plant extract comprises from 7 to 60%, from 10 to 50%, or from 15 to 40% by weight of lawsone relative to the total weight of the dry extract. Such an extract is referred to below as “Lawsonia inermis extract rich in lawsone”. Unlike the Lawsonia inermis extract described above, the Lawsonia inermis extract rich in lawsone is used for coloring purposes - due to its high content of lawsone-.

An extract of Lawsonia inermis comprising from 7 to 60%, from 10 to 50%, or from 15 to 40%, by weight of lawsone can be as described in document WO2019/115651 or in French patent application no. on June 12, 2019. Lawsonia inermis extract rich in lawsone can be obtained by a process comprising the following steps: a) maceration of the aerial parts of Lawsonia inermis in water, carried out at a pH between 4 and 8, during which the glycosylated derivatives of lawsone, such as the hennosides, initially present in the aerial parts of Lawsonia inermis are partially or totally hydrolyzed enzymatically, resulting in the production of an aqueous solution containing lawsone; b) addition of an organic solvent to the aqueous solution obtained at the end of step a), the organic solvent being chosen from linear or branched C4-C12 alcohols and solvents in which the miscibility of water is less than 10%, or even less than 5% by weight at 25° C., resulting in the formation of an aqueous phase and an organic phase; c) recovery of the organic phase obtained at the end of step b); and d) concentration of the organic phase recovered at the end of step c); e) possibly drying; to give an extract rich in lawsone. The aerial parts of Lawsonia inermis can be fresh or dry, preferably dry leaves, twigs or mixtures thereof. The aerial parts of Lawsonia inermis are preferably finely ground.

The process steps may be as described for the process for the preparation of the Lawsonia inermis extract low in lawsone. Typically, this process makes it possible to obtain an extract rich in lawsone comprising more than 50% or more than 60% or even more than 70% by weight of the lawsone initially present in the free form or in the form of glycosylated derivatives of lawsone, such as hennosides, in the aerial parts of Lawsonia inermis.

In certain embodiments, the method may comprise a step of adding a support between steps c) and d). The support is preferably as described above in connection with the preparation of the extracts of Sorghum bicolor. Step d) is then preferentially followed by a drying step leading to the production of a dry extract of Lawsonia inermis. The extract can thus be a standardized extract. In certain embodiments, the dry extract of standardized Lawsonia inermis comprises a lawsone content ranging from 0.6% to 1.4% or from 1 to 1.3%, in particular a content of approximately 1.3% by weight of lawsone relative to the total weight of the standardized dry extract.

In some embodiments, the method further includes a pigment extraction step, also called a bleaching step. The pigments extracted during said bleaching step are in particular chlorophylls. On the other hand, it is understood that lawsone is not one of the pigments that the bleaching step aims to eliminate. The pigment extraction step can in particular be carried out using an organic solvent.

If the exact qualitative and quantitative compositions of an extract of Lawsonia inermis rich in lawsone obtained by such a process cannot be reasonably determined, the extract is nevertheless characterized by a high content of lawsone (from 7 to 60%, from 10 to 50%, or 15 to 40%, by weight of lawsone relative to the total weight of the dry extract).

Typically, the Lawsonia inermis extract rich in lawsone obtained by such a process comprises from 1% to 40% or from 2% to 30% by weight of phenolic compounds relative to the total weight of the dry extract.

The phenolic compounds present in the extract especially include luteolin (flavonoid), apigenin (flavonoid) and 2,3,4,6-tetrahydroxyacetophenone. The lawsone-rich extract may also include 3,4,5-trihydroxyacetophenone and/or 1,2-dihydroxy-4-O-glycosyloxynaphthalene. Thus, the extract rich in lawsone can also be characterized by the presence of luteolin, apigenin and 2,3,4,6-tetrahydroxyacetophenone, and possibly by the presence of 3,4,5-trihydroxyacetophenone and/or 1,2-dihydroxy-4-O-glycosyloxynaphthalene. Lawsonia inermis extract rich in lawsone may include other phenolic compounds, such as coumaric acid, in particular para-coumaric acid, 1,2-dihydroxy-4-O-glycosyloxynaphthalene, gallic, other flavonoids, such as catechin, 3',4',5,7-tetrahydroxyflavanone, 3',5,7-trihydroxy-4'-methylflavone and/or glycosides of such compounds, such as lalioside, myrciaphenone A, 1,2-dihydroxy-4-O-glycosyloxynaphthalene (also called 4-0-0-D-glucopyranoside), luteolin-4'-O-glucoside, apigenin-7-OP -glucoside, luteolin-3'-O-glucoside, apigenin-4'-OP-glucoside and luteolin-6-C-neohesperidoside. In particular, the extract contains gallic acid, coumaric acid, in particular para-coumaric acid; flavonoids, such as catechin, 3',4',5,7-tetrahydroxyflavanone, 3',5,7-trihydroxy-4'-methylflavone; and/or the glycosides of such compounds, such as lalioside, myrciaphenone A, 1,2-dihydroxy-4-O-glycosyloxynaphthalene, luteolin-4'-O-glucoside, apigenin-7-OP-glucoside , luteolin-3'-O-glucoside, apigenin-4'-OP-glucoside and luteolin-6-C-neohesperidoside. Advantageously, the extract contains coumaric acid and/or glycosilated luteolin, in particular luteolin-6-C-neohesperidoside.

Flavonoids, such as luteolin and apigenin, exhibit interesting biological properties, such as free radical scavenging and antioxidant effects [Romanov et al., Neoplasma 2001, 48(2), 104-107] as well as anti-inflammatory activity. Combined with their UV absorption capacity, these effects enable them to provide protection against UV radiation and thus play a photoprotective role for the hair [Saewan et al., JAPS 2013, 3(9), 129-141] ,

In addition, apigenin has been shown to promote hair growth [Huh et al. Arch. Dermatol. Res., 2009, 301, 381-385],

Polyphenols, such as 2,3,4,6-tetrahydroxyacetophenone, and phenolic acids, such as para-coumaric acid, also exhibit antioxidant and photoprotective properties [Nichols et al., Arch. Dermatol. Res. 2010, 302, 71-83],

The dosage of the phenolic compounds can in particular be carried out by spectrophotometry, according to the method described in the experimental section (Method 4).

Lawsonia inermis extract rich in lawsone may also include sterols, such as P-sitosterol, triterpenes, such as lupeol.

Typically, the Lawsonia inermis extract rich in lawsone also comprises less than 2%, less than 1.5% or less than 1% by weight of proteins, peptides or amino acids relative to the total weight of the dry extract. In certain embodiments, the extract comprises from 0 to 1% or from 0.1 to 1% by weight of proteins, peptides or amino acids relative to the total weight of the dry extract. The determination of free amino acids, peptides and proteins can in particular be carried out by ninhydrin spectrophotometry, according to the method described in the experimental section (Method 6).

Typically, Lawsonia inermis extract rich in lawsone also includes chlorophylls, in particular chlorophyll a and/or chlorophyll b. The chlorophyll content is less than 25% or less than 20% or less than 10% by weight relative to the total weight of the dry extract. In certain embodiments, the Lawsonia inermis extract comprises less than 5% or less than 2% by weight of chlorophylls, relative to the total weight of the dry extract, or even does not comprise any chlorophylls.

The dosage of chlorophylls can in particular be carried out by weight dosage, according to the method described in the experimental section (Method 7).

Typically, Lawsonia inermis extract rich in lawsone contains less than 5% by weight, relative to the total weight of the dry extract, of saccharide compounds. In certain embodiments, the Lawsonia inermis extract comprises 0.1 to 5% or 0.5 to 5% by weight of saccharide compounds relative to the total weight of the dry extract.

The content of saccharide compounds can in particular be determined by colorimetric assay with dinitrosalicylic acid (Method 5).

In certain embodiments, the Lawsonia inermis extract rich in lawsone may be in the form of a dry extract, advantageously in the form of a powder, in particular with a particle size of less than 250 μm.

In certain embodiments, the coloring agent derived from plants is a standardized dry extract of Lawsonia inermis rich in lawsone. The standardized dry extract consists of a support and an extract of Lawsonia inermis rich in lawsone obtained according to the process described above.

In certain embodiments, the standardized dry extract of Lawsonia inermis rich in lawsone comprises from 0.6 and 1.4% or from 1.3% to 1.3%, in particular approximately 1.3% by weight of lawsone relative to the total weight of the standardized dry extract, luteolin, apigenin and 2,3,4,6-tetrahydroxyacetophenone. It may also contain coumaric acid, in particular para-coumaric acid. It may additionally contain glycosilated luteolin, in particular luteolin-6-C-neohesperidoside. It may additionally contain 3,4,5-trihydroxyacetophenone and/or 1,2-dihydroxy-4-O-glycosyloxynaphthalene. The standardized dry extract of Lawsonia inermis typically includes (content expressed in relation to the total weight of the standardized dry extract):

- 0.2 and 3.0% by weight of phenolic compounds; - from 0.05 to 1.0% by weight of luteolin;

- from 0.01 to 0.5% by weight of apigenin;

- from 0.01 to 0.1% by weight of para-coumaric acid;

- From 0.05 to 1.0% by weight of 2,3,4,6-tetrahydroxyacetophenone;

- less than 0.2% by weight of proteins, peptides or amino acids, advantageously from 0 to 0.2% by weight, advantageously from 0.1 to 0.2% by weight, of proteins, peptides or amino acids ;

- less than 0.5% by weight of saccharide compounds, advantageously from 0.01 to 0.5% by weight, advantageously from 0.05 to 0.5% by weight, of saccharide compounds;

- at least 80%, at least 90%, at least 92%, or at least 95% by weight of support, relative to the total weight of the standardized dry extract.

Typically, it does not include chlorophylls.

Preferably, the standardized extract is in the form of a dry extract, advantageously in the form of a powder, in particular with a particle size of less than 250 μm.

Indigo-bearing plants can be chosen from indigo (Indigofera tinctorial), dyer's knotweed (Polygonum tinctorium or Persicaria tinctoria), dyer's pastel (Isatis tinctoria L.), Couroupita guianensis (in Anglo-Saxon: Cannon ball tree), wild indigo (Baptisia tinctoria), dyer's croton (Chrozophora tinctoria), dyer's laurel (Wrightia tinctoria), indigo-vine (Philenoptera cyanescens = Lonchocarpus cyanescens), L. laxiflorus (Lonchocarpus laxiflorus), Marsdénia tinctoria ( Asclepiadaceae), Assam indigo (Strobilanthes cusia or Strobilanthes flaccidifolius) and their combinations.

The coloring agent then typically comprises indirubin and/or leuco-indigo.

The coloring agent from an indigo plant can be:

- an extract of indigo leaves, in particular an aqueous or hydroalcoholic or alcoholic extract, or a powder of indigo leaves;

- an extract of knotweed leaves, in particular an aqueous or aqueous-alcoholic or alcoholic extract, or a powder of knotweed leaves;

- an extract of dyers' pastel leaves, in particular an aqueous or hydroalcoholic or alcoholic extract, or a powder of dyers' pastel leaves;

- an extract of flowers and/or fruits of Couroupita guianensis, in particular an aqueous or hydroalcoholic or alcoholic extract, or a powder of flowers and/or fruits of Couroupita guianensis;

- a wild indigo whole plant extract, in particular an aqueous or hydroalcoholic or alcoholic extract, or a wild indigo whole plant powder;

- an extract of the whole plant of dyers' croton, in particular an aqueous or aqueous-alcoholic or alcoholic extract, or a powder of the whole plant of dyers'croton; - a whole plant extract of laurel dyers, in particular an aqueous or hydroalcoholic or alcoholic extract, or a powder of whole plant laurel dyers;

- an extract of liana-indigo leaves, in particular an aqueous or aqueous-alcoholic or alcoholic extract, or a powder of liana-indigo leaves;

- an extract of L. laxiflorus leaves, in particular an aqueous or hydroalcoholic or alcoholic extract, or a powder of L. laxiflorus leaves;

- a whole plant extract of Marsdénia tinctoria, in particular an aqueous or hydroalcoholic or alcoholic extract, or a whole plant powder of Marsdénia tinctoria; Where

- a whole Assam indigo plant extract, in particular an aqueous or hydroalcoholic or alcoholic extract, or a whole Assam indigo plant powder.

Source plants of red pigment can be chosen from sorghum, hibiscus and their combinations.

The coloring agent then typically comprises anthocyanins.

The coloring agent from a plant source of red pigment can be:

- an aqueous or hydroalcoholic extract of the aerial parts, in particular the stem, of sorghum or a powder of the aerial parts, in particular the stem, of sorghum; Where

- an aqueous or hydroalcoholic extract of flowers, in particular dried flowers (karkadé), of hibiscus or a powder of flowers, in particular dried flowers (karkadé), of hibiscus.

A plant source of red or purple to black pigment can be logwood.

The coloring agent derived from a plant source of red or purple to black pigment may be an aqueous or hydroalcoholic extract of logwood, in particular logwood heartwood, or a powder of logwood, in particular logwood heartwood.

Source plants for yellow pigment can be selected from gardenia, turmeric, saffron, birch, chamomile, reseda and combinations thereof.

The coloring agent then typically comprises crocins.

The coloring agent from a plant source of yellow pigment can be:

- an aqueous or hydroalcoholic extract of the fruits of Gardenia or a powder of the fruits of Gardenia. Such a coloring agent can for example be a Gardenia extract as described in the document WO2018162760. In particular, the Gardenia extract or powder contains a mass fraction of crocins ranging from 0.1 to 10%, preferably from 1 to 5%, relative to the total weight of the dry extract or dry powder;

- an aqueous or hydroalcoholic extract of the turmeric rhizome or a powder of the turmeric rhizome; - an aqueous or hydroalcoholic extract of saffron stigmas or a powder of saffron stigmas;

- an aqueous or hydroalcoholic extract of birch leaves or a powder of birch leaves;

- an aqueous or hydroalcoholic extract of flowers, in particular the ligule, of chamomile or a powder of flowers, in particular the ligule, of chamomile; Where

- an aqueous or hydroalcoholic extract of reseda roots or a powder of reseda roots.

Source plants of red to bluish-green pigment can be chosen from elderberry, blueberry, aronia and their combinations.

The coloring agent from a pigment-source plant can be:

- an aqueous or hydroalcoholic extract of elderberry fruits or an elderberry fruit powder;

- an aqueous or hydroalcoholic extract of blueberry fruit or a powder of blueberry fruit; Where

- an aqueous or hydroalcoholic extract of aronia fruit or a powder of aronia fruit.

The source plants of tannins can be chosen from chestnut, Emblica officinalis, pomegranate and their combinations. The plants that are sources of tannins make it possible to darken the color, in particular towards gray to dark brown hues.

The coloring agent then typically comprises tannins.

The coloring agent from a plant source of tannins can be:

- an aqueous or hydroalcoholic extract of chestnut wood or a powder of chestnut wood;

- an aqueous or hydroalcoholic extract of fruits of Emblica officinalis or a powder of fruits of Emblica officinalis; Where

- an aqueous or hydroalcoholic extract of fruits, in particular the pericarp, of pomegranate or a powder of fruits, in particular the pericarp, of pomegranate.

The plant source of brown pigment can be the rhapontic. The coloring agent from a plant source of brown pigment can be an aqueous or hydroalcoholic extract of rhapontic roots or a powder of rhapontic roots (in Anglo-Saxon: Rheum rhapontica root powder).

In some embodiments, the coloring composition does not include dodder extract or multiflower knotweed extract. All the extracts and powders mentioned above can benefit from the designation "BIO", that is to say that they can be prepared from raw materials certified in organic farming and that their preparation does not involve a step of chemical synthesis. They can be obtained by eco-responsible processes. They can also benefit from the designation “Vegan”.

However, the coloring agent can also be obtained by semi-synthetic or synthetic methods. For example, the coloring agent can be chlorophyllin. Chlorophyllin is a source of green pigment. Chlorophyllin can be obtained by extraction according to a semi-synthetic process involving a step of saponification of chlorophyll.

Plant sources of chlorophyll can be chosen from alfalfa, white mulberry, nettle, algae, and combinations thereof.

Chlorophyll can be extracted:

- aerial parts of alfalfa with an organic solvent such as acetone, alcohols, alkanes (hexane, heptane) or supercritical CO2;

- aerial parts of white mulberry with an organic solvent such as acetone, alcohols, alkanes (hexane, heptane) or supercritical CO2;

- aerial parts of nettle with an organic solvent such as acetone, alcohols, alkanes (hexane, heptane) or supercritical CO2; Where

- algae thallus with an organic solvent such as acetone, alcohols, alkanes (hexane, heptane) or supercritical CO2.

Compositions and cosmetic compositions for coloring keratin fibers

The coloring compositions, in particular the coloring cosmetic compositions for coloring keratin fibres, comprise:

- a first coloring agent, the first coloring agent comprising, or consisting of, an extract of the aerial parts of Sorghum bicolor (L.) Moench comprising at least 2.5% by weight of apigeninidine relative to the total weight of the 'dry extract ;

- a second coloring agent, the second coloring agent comprising, or consisting of, an extract of the aerial parts of Lawsonia inermis comprising less than 0.6% by weight of lawsone, at least 10% by weight of phenolic compounds relative to the total weight of dry extract;

- optionally one or more additional coloring agents derived from dyeing plants, microorganisms or microalgae, the additional coloring agent being different from the first and second coloring agents. In certain embodiments, the coloring compositions, in particular the coloring cosmetic compositions for coloring keratin fibres, comprise:

- a first coloring agent, the first coloring agent being a standardized extract, the standardized extract comprising an extract of the aerial parts of Sorghum bicolor (L.) Moench comprising at least 2.5% by weight of apigenidin relative to the total weight of dry extract;

- a second coloring agent, the second coloring agent being an extract of the aerial parts of Lawsonia inermis comprising less than 0.6% by weight of lawsone, at least 10% by weight of phenolic compounds relative to the total weight of the dry extract ;

- optionally one or more additional coloring agents from dyeing plants, microorganisms or microalgae, the additional coloring agent being different from the first and second coloring agents.

The extract of the aerial parts of Sorghum bicolor (L) Moench, standardized or not, and the extract of the aerial parts of Lawsonia inermis can be obtained by the methods described above.

In certain embodiments, the coloring compositions, in particular the coloring cosmetic compositions for coloring keratin fibres, comprise:

- a first coloring agent, the first coloring agent being a standardized extract of the aerial parts of Sorghum bicolor (L.) Moench comprising from 2.4% to 8% by weight of apigeninidine relative to the total weight of the extract standardized dry;

The extract of the aerial parts of Sorghum bicolor (L.) Moench, standardized or not, and the extract of the aerial parts of Lawsonia inermis can be obtained by the methods described above.

Thus, in other words, the coloring compositions, in particular the coloring cosmetic compositions, of the present invention comprise an extract of aerial parts of Sorghum bicolor (L.) Moench which can be obtained by an extraction process comprising the following steps : a) agitation of the aerial parts of Sorghum bicolor (L.) Moench in an organic solvent chosen from alcohols, esters, ketones, ethers, chlorinated solvents or mixtures thereof or in a hydroalcoholic solution comprising at least 50%, at at least 60%, at least 70%, at least 80% or even at least 90% by volume of an alcohol miscible in water, preferably in ethanol or in a hydroalcoholic solution comprising at least 70%, at least 80% or even at least 90% by volume of ethanol; b) liquid/solid separation; c) recovery of the liquid phase; d) concentration of the liquid phase obtained in step c) and elimination of the alcohol; e) possibly drying.

In certain embodiments, the coloring compositions, in particular the coloring cosmetic compositions of the present invention, comprise a standardized extract of aerial parts of Sorghum bicolor (L.) Moench obtainable by a process comprising the following steps: a ) agitation of the aerial parts of Sorghum bicolor (L.) Moench in an organic solvent or an aqueous-alcoholic solution comprising at least 70%, at least 80% or even at least 90% by volume of a water-miscible alcohol, preferably at least 70%, at least 80% or even at least 90% by volume of alcohol; b) liquid/solid separation; c) recovery of the liquid phase; d) concentration of the liquid phase obtained in step c) and elimination of the alcohol; e) addition of a carrier as described above; and f) drying.

The coloring compositions, in particular the coloring cosmetic compositions, of the present invention may comprise an extract of aerial parts of Lawsonia inermis which can be obtained by an aqueous, hydroalcoholic or alcoholic extraction process.

In certain embodiments, the coloring compositions, in particular the coloring cosmetic compositions, of the present invention comprise an extract of aerial parts of Lawsonia inermis which can be obtained by an extraction process comprising the following steps: a) agitation of the aerial parts (eg crushed leaves) of Lawsonia inermis in an extraction solution (water or hydroalcoholic solution), typically in a ratio (m/v) aerial parts of Lawsonia /nerm/s/extraction solution ranging from 1/2 to 1/10, preferably from 1/4 to 1/8, at a temperature ranging from 30°C to 50° VS ; b) liquid/solid separation; c) recovery of the liquid phase; d) concentration of the liquid phase obtained in step c); e) possibly drying.

In certain embodiments, the coloring compositions, in particular the coloring cosmetic compositions, of the present invention comprise an extract of aerial parts of Lawsonia inermis which can be obtained by an extraction process comprising the following steps: a) maceration of the aerial parts of Lawsonia inermis in water, carried out at a pH between 4 and 8, during which the glycosylated derivatives of lawsone, such as hennosides, initially present in the aerial parts of Lawsonia inermis are partially or totally hydrolyzed enzymatically, resulting in the production of an aqueous solution containing lawsone; b) addition of an organic solvent to the aqueous solution obtained at the end of step a), the organic solvent being chosen from linear or branched C4-C12 alcohols and solvents whose miscibility in water is less than 10%, or even less than 5% by weight at 25° C., resulting in the formation of an aqueous phase and an organic phase; c) recovery of the aqueous phase obtained at the end of step b); d) concentration of the aqueous phase recovered at the end of step c); and e) optionally drying.

In certain embodiments, the coloring compositions, in particular the coloring cosmetic compositions for coloring keratin fibers, comprise, relative to the total weight of the dry compositions:

- from 5 to 90%, in particular from 5 to 50%, preferably from 10% to 30%, or from 50% to 90%, by weight of a first coloring agent, the first coloring agent comprising, or consisting in, an extract of the aerial parts of Sorghum bicolor (L.) Moench comprising at least 2.5% by weight of apigeninidine relative to the total weight of the dry extract;

- from 10 to 90%, in particular from 10 to 50% or from 50% to 90%, by weight of a second coloring agent, the second coloring agent comprising, or consisting of, an extract of the aerial parts of Lawsonia inermis comprising less than 0.6% by weight of lawsone and at least 10% by weight of phenolic compounds, and generally at least 60% by weight of saccharide compounds relative to the total weight of the dry extract; - from 5 to 90%, in particular from 10 to 50% or from 50% to 90%, of one or more additional coloring agents derived from plants, the additional coloring agent being different from the first and second coloring agents.

Preferably, the cosmetic compositions are in powder form (in dry form).

In certain embodiments, the coloring compositions, in particular the cosmetic compositions for coloring keratin fibres, comprise, relative to the total weight of the dry compositions:

- from 5 to 90%, in particular from 10 to 50% and preferably from 10% to 30%, or from 50% to 90%, by weight, of a first coloring agent, the first coloring agent being an extract standardized, the standardized extract comprising an extract of the aerial parts of Sorghum bicolor (L.) Moench comprising at least 2.5% by weight of apigenidin relative to the total weight of the dry extract;

- from 10 to 90%, in particular from 10 to 50%, or from 50% to 90%, by weight of a second coloring agent, the second coloring agent being an extract of the aerial parts of Lawsonia inermis comprising less than 0 6% by weight of lawsone and at least 10% by weight of phenolic compounds, generally at least 60% by weight of saccharide compounds relative to the total weight of the dry extract;

- from 5 to 90%, in particular from 10 to 50% or from 50% to 90%, by weight of one or more additional coloring agents derived from dyeing plants, microorganisms or microalgae, the coloring agent additional being different from the first and second coloring agents.

In certain embodiments, the coloring compositions, in particular the cosmetic compositions for coloring keratin fibers comprise, relative to the total weight of the dry compositions:

- from 5 to 90%, in particular from 10 to 50% and preferably from 10% to 30%, or from 50% to 90%, by weight of a first coloring agent, the first coloring agent being a standardized extract aerial parts of Sorghum bicolor (L) Moench comprising from 2.4% to 8% by weight of apigenidin relative to the total weight of the standardized dry extract;

- from 10 to 90%, in particular from 10 to 50%, or from 50% to 90%, by weight of a second coloring agent, the second coloring agent being an extract of the aerial parts of Lawsonia inermis comprising less than 0 6% by weight of lawsone and at least 10% by weight of phenolic compounds, generally at least 60% by weight of saccharide compounds relative to the total weight of the dry extract; - from 5 to 90%, in particular from 10 to 50% or from 50% to 90%, by weight of one or more additional coloring agents derived from dye plants, micro-organisms or micro-algae, the agent additional coloring agent being different from the first and second coloring agents.

The support may be as described above.

The coloring agents derived from dyeing plants, microorganisms or microalgae can be as described above. Typically, the cosmetic composition comprises a maximum of five additional coloring agents, preferably a maximum of two additional coloring agents or even a single additional coloring agent. This limited number limits the risks of intolerance and incompatibilities.

In some embodiments, the additional coloring agent is a Lawsonia inermis extract rich in lawsone as described above. Preferably, the coloring agent is a standardized dry extract of Lawsonia inermis as described above.

In certain embodiments, the additional coloring agent is derived from an indigo plant as described above. More particularly, the additional coloring agent can be an extract of indigo leaves, in particular an aqueous or aqueous-alcoholic or alcoholic extract, or a powder of indigo leaves.

The coloring hair compositions comprising extracts of Sorghum bicolor and Lawsonia inermis as described above and a coloring agent derived from an indigo plant make it possible to obtain colorations with intense mahogany reflections but also dark chestnut or even blond or copper colors .

The cosmetic compositions can also comprise one or more cosmetically acceptable excipients. The expression “cosmetically acceptable excipient” denotes ingredients suitable for the formulation of cosmetic compositions of the cream, lotion, shampoo, emulsion type or any formulation suitable for application to keratin fibres, in particular the hair and the scalp. Examples of cosmetically acceptable excipients include, without limitation, surfactants, thickeners, acidity correctors (e.g. citric acid, acetic acid, sodium, calcium or potassium carbonates and bicarbonates), texture agents and /or touch (e.g. maltodextrin, fructans such as inulin, bamboo silica, cellulose, polysaccharides such as guar gum, xanthan gum, alginates, carrageenan, locust bean gum, gum arabic, acacia gum, konjac, pectins, Ispaghul, Flax, Okra, Konjac, Hibiscus, Calendula, Banana, Baobab, Acanthus, Aloes, marshmallow, Inule, Cassia tora...), preservatives, perfumes, dyes, chemical or mineral filters, moisturizing agents, thermal waters, etc. The composition may include at least one acidity corrector, advantageously chosen from organic acids, in particular citric acid, acetic acid, carbonates and bicarbonates, in particular sodium, calcium or potassium bicarbonate.

The cosmetic compositions can also comprise an agent which promotes the adhesion of the dyes to the keratin fibers (eg Cassia (neutral henna), Aloe vera, inulin).

The compositions can be formulated in various forms suitable for topical administration. Examples of formulation suitable for topical administration include creams, emulsions, milks, ointments, lotions, oils, aqueous, hydroalcoholic or glycolic solutions, powders, sprays, shampoos.

In the embodiments described above, the sum of the percentages of the first coloring agent, second coloring agent and additional coloring agents may be equal to 100. Alternatively, the composition may additionally comprise one or more excipients cosmetically acceptable, the proportion of these cosmetically acceptable agents then making it possible to reach 100% by weight.

Kits or combination products

The invention also relates to a kit, or combination product, comprising the following components: a component comprising a mixture of an extract of aerial parts of Lawsonia inermis and of at least one bicolor Sorghum extract and a component comprising at least a cosmetically acceptable excipient.

This excipient may be as defined above for the cosmetic composition, and in particular be chosen from the group comprising a texture and/or feel agent, an acidity corrector and mixtures thereof.

The component comprising a combination of an extract of aerial parts of Lawsonia inermis and at least one extract of Sorghum bicolores!. advantageously in dry form, in particular powder.

Advantageously, the component is a hair care product chosen from the group comprising shampoo, conditioner, hair balm, hair lotion, hair cream, etc.

Method of staining keratin fibers

The present invention also relates to a cosmetic method for dyeing keratin fibers comprising the application to the keratin fibers of an aqueous composition comprising a dye composition, in particular a cosmetic composition for dyeing keratin fibers as described above.

In particular, the cosmetic coloring method includes the following steps: a) supply of a coloring composition, in particular a cosmetic composition for coloring keratin fibers as described above, in particular in dry form, in particular in powder form; b) preparation of an aqueous composition by adding water to the dye composition, in particular a cosmetic composition for dyeing keratin fibers, at a temperature ranging from 20 to 98° C.; c) application of the aqueous composition to the keratin fibres; d) optional heating of the keratin fibres; e) rinsing.

Steps c) and e) can be repeated. Generally, steps c) and e) are not repeated.

It has been found that a small amount of composition according to the invention, with a reduced amount of water, could suffice for hair coloring of an adult head. Traditionally, with a natural coloring comprising a powder or a plant extract, it is recommended to mix at least 100 g of powder with at least 300 g of water, which leads to a "poultice" preparation, very thick, unpleasant to handle and apply.

According to the invention, during step a), less than 50 g of powder of the composition according to the invention is advantageously provided, more advantageously less than 30 g, even more advantageously less than 25 g, for example from 15 g to 30 g, preferably 15 g to 25 g, more preferably about 20 g.

During step b) water is advantageously added in sufficient quantity to prepare a composition of 100 g or 150 g. The water added can be room temperature water (tap water) or hot water (heated tap water). The temperature of the hot water can be at least 50° C., advantageously at least 70° C., or even at least 90° C., as easily obtained in a kettle.

Thus 100 g or 150 g of aqueous composition are sufficient to obtain a preparation which can be applied to the head. The composition obtained has a pleasant galenic, which does not have the very thick and unpleasant appearance, "poultice", of the known natural colorings.

The composition can be applied to dry or wet keratin fibres. The application can be carried out as in the chemical hair coloring methods, with in particular an exposure time step before the rinsing step. In particular, the exposure time step also comprises a heating step, in particular to a temperature between 25°C and 65°C, advantageously between 30°C and 60°C, in particular 55°C or at particularly 35°C. Alternatively, the exposure time step can be carried out at ambient temperature, ranging in particular from 20° C. to 30° C., without additional heat input and thus without a heating step. Typically, a short exposure time is respected, that is to say an exposure time of less than 1 hour, preferably less than 45 minutes.

In certain embodiments, the cosmetic composition can be a ready-to-use composition or it can be prepared at the time of the implementation of the method by mixing the first coloring agent, second coloring agent and possible coloring agents additional.

Another advantage of the method according to the invention, and of the composition according to the invention, is that the coloration obtained, in particular on keratin fibers such as the hair, is maintained despite repeated washings.

Thus, advantageously, the colored keratin fibers do not exhibit a reduction in shine of more than 8 units, advantageously not more than 6 units, more advantageously not more than 5 units, even more advantageously not more than 4 units, even more advantageously no more than 3 units, following 10, advantageously 15, post-staining washes, brightness evaluated by measuring the dE* parameter, according to the protocol described in the examples.

Alternatively, the cosmetic method for coloring keratin fibres, in particular human fibres, comprises the following steps: a.1) Providing one of a first coloring agent as described above, optionally with at least one cosmetically acceptable excipient as defined previously, in particular in dry form, in particular in powder form; b.1) Prepare an aqueous composition, by adding to the powder of step a.1) an aqueous composition, in particular water, at a temperature between 20° C. and 98° C. and mixing; c.1) Applying the composition of step b.1) to keratin fibers, optionally by heating the fibers thus treated; d.1) Rinse; a.2) Providing a second coloring agent as described above, optionally with at least one cosmetically acceptable excipient as defined previously, in particular in dry form, in particular in powder form; b.2) Prepare an aqueous composition, by adding to the powder from step a.2) an aqueous composition, in particular water, at a temperature between 20° C. and 98° C. and mixing; c.2) Applying the composition of step b.2) to keratin fibers, optionally by heating the fibers thus treated; d.2) Rinse; e) Optionally, but not preferably, repeating steps c.1) and d.1) and/or c.2) and d.2).

Alternatively, the cosmetic method for coloring keratin fibres, in particular human fibres, comprises the following steps: a.1) Providing a second coloring agent as described above, optionally with at least one cosmetically acceptable excipient as defined above, in particular in dry form, in particular in powder form; b.1) Prepare an aqueous composition, by adding to the powder of step a.1) an aqueous composition, in particular water, at a temperature between 20°C and 98°C and mixing; c.1) Applying the composition of step b.1) to keratin fibres, optionally by heating the fibers thus treated; d.1) Rinse; a.2) Providing a first coloring agent as described above, optionally with at least one cosmetically acceptable excipient as defined previously, in particular in dry form, in particular in powder form; b.2) Prepare an aqueous composition, by adding to the powder from step a.2) an aqueous composition, in particular water, at a temperature between 20° C. and 98° C. and mixing; c.2) Applying the composition of step b.2) to keratin fibres, optionally by heating the fibers thus treated; d.2) Rinse; e) Optionally, but not preferably, repeating steps c.1) and d.1) and/or c.2) and d.2).

The steps of these two alternatives are advantageously carried out as described above, with the necessary adaptation in view of the sequencing.

To any one of steps a.1) or a.2) it is also possible to add an additional coloring agent as described above, or, alternatively or in addition, provide a series of steps a.3) to c.3), similar to steps a.1) to c.1) but in which the coloring agent is the additional coloring agent. EXAMPLES

Characterization of extracts: method of analysis

Method 1: apigenidin assay

Material and method HPLC UV reverse phase detection 474 nm

- Column: SymmetryShield RP18 5 µm 250x4.6 mm Waters or equivalent.

- Mobile phase: Solvent A: water + 1% formic acid

Solvent B: methanol + 1% formic acid

Preparation of solutions

- Control solution:

Weigh a mass my close to 5 mg of apigeninidine chloride. Dissolve in 20 mL of solvent B. Dilution at 1/2, 1/10th ^and 1/20th.

- Trial solution:

Weigh a mass m _e close to 80 mg of substance to be analyzed. Dissolve in 20 mL of solvent

B. 10 min of ultrasound and manual shaking. Filter.

Results

The chromatograms of the control and test solutions show a characteristic and identical spectrum peak; the control peak (Area AT) corresponds in retention time and in spectrum to the main peak of the test (Area Ae).

The content of apigeninidine (Tapig) in the extract is given by the formula:

Method 2: Measuring Color Intensity

In a 200 mL flask, introduce approximately 100 mg of product, weighed exactly and complete with methanol at 0.1% hydrochloric acid (0.05 g%mL solution).

Ultrasonic shaking for 10 min. Take 2.5 ml_ under magnetic stirring (the product does not dissolve completely), introduce them into a 25 mL flask and complete with methanol at 0.1% hydrochloric acid (0.005 g%mL solution).

Filter.

Measure the absorbance of the solution between 200 and 800 nm.

The coloring intensity corresponds to the absorption maximum at 480 nm (± 5 nm) of a 1 g % mL extract solution.

DO: maximum absorbance around 480 nm (± 5 nm)

C: concentration of the solution analyzed in g%mL

Method 3: Assay of lawsone by C.L.H.P

This method can be applied for:

A. the dosage of lawsone in an extract

B. the determination of total lawsone present in free form or in the form of glycosylated derivatives of lawsone in the aerial parts of lawsonia inermis, obtained by acid hydrolysis, and thus quantify the potential of lawsone in the plant,

C. the dosage of the lawsone formed by the enzymes

Reagents

Lawsone > 97% (HPLC) SIGMA- ref: H46805

Dichloromethane for analysis.

Sulfuric acid for analyses.

Methanol for analysis

HPLC quality water.

HPLC grade acetonitrile.

HPLC grade trifluoroacetic acid.

Conditions C.L.H.P.

- Column: XBridge C18, 3.5 µm, 4.6 x 150 mm Waters, Oven: 40°C

- Solvents:

S-A: 0.1% trifluoroacetic acid in water

S-B: 0.1% trifluoroacetic acid in acetonitrile

- Gradient: T0 min 40% S-A; T 1 min 40% S-A; T 10 min 5% S-A; T 11 min 5% S-A; T

11.1min 40% S-A

- Wavelength: X=278 nm - Flow rate: 1mL/min

- Injection: 10 µL

Sample preparation

For whole or coarsely ground leaves: 50 g of leaves are ground and then sieved through a 0.355 μm sieve.

For leaf powders: Use 50 g of leaf powder as is.

Preparation of solutions

Sample Solutions

Solution of lawsone at 0.3 mg/mL in methanol/ethanol 1/1. Dilute 1/10th, ^1/20 , 1/100 in methanol/water 1/1.

Test solutions

- Test solution A (dosage of the lawsone present in an extract): Dissolve 50 mg of extract in 100 mL of methanol/water 1/1. Dissolve with ultrasound. Filtration on Acrodisc GFGHP. Inject 10 µL.

- Test solution B (determination of total lawsone): In a volumetric flask, introduce 80 mg of leaf powder. Add in 50 mL of H2SO42N. Heat at 97°C for 30 min. Let cool. Add methanol q.s.p. 100mL. Filter the solution through Acrodisc GF GHP 0.45 µm. Inject 10 µL of the filtrate.

- Test solution C (dosage of the lawsone formed by the enzymes): In a volumetric flask, introduce 80 mg of leaf powder. Add to 50 mL of deionized water. Place in an ultrasonic bath for 30 min between 30 and 40°C. Let cool. Add methanol q.s.p. 100mL. Filter the solution through Acrodisc GF GHP 0.45 µm. Inject 10 µL of the filtrate.

Results

Use the regression line calculated with the control solutions to determine:

A. the lawsone content of the extract,

B. total lawsone content, and/or

C. the content of lawsone formed by the enzymes.

Method 4: Spectrophotometric determination of phenolic compounds

The content of phenolic compounds in the extract can be assessed by spectrophotometry according to the method of the European Pharmacopoeia, version 9.0, 2.8.14.

The solutions to be tested are prepared by dissolving 25 mg of extract in 100 mL of water. The content of phenolic compounds is expressed with reference to pyrogallol.

Luteolin and apigenin were especially titrated by analytical HPLC carried out with a C18 column (XBridge 100 C18; 3.5 mm, 150 mm x 4.6 mm) under conditions gradient (see below) with H2O! 0.1% trifluoroacetic acid (A) and acetonitrile / 0.1% trifluoroacetic acid (B) as eluent:

Gradient conditions: tO A 18% B 82%; tl min: A 18% B 82%; 10 mins A 50% B 50%; 10.1 min: A 18% B 82%

UV detection is at 340 nm for apigenin and 310. The flow rate was 1 mL/min and the temperature 40°C. Pure luteolin, apigenin and p-coumarin were used for calibration.

Method 5: colorimetric assay of saccharide compounds before and after hydrolysis

Principle: Colorimetric assay of saccharide compounds by dinitrosalicylic (DNS) compared to glucose before and after hydrolysis. The results are expressed as a percentage of saccharide compounds relative to glucose.

Reagents:

DNS reagent: Dissolve 30 g of sodium potassium ditartrate in 50 ml of water. Add 20 mL of 2N soda. Dissolve 1 g of dinitrosalicylic acid (DNS) by heating slightly. Make up to 100 mL with water.

Preparation of the solutions:

Preparation of the standard range: dissolve 5 mg of glucose in 10 mL of water.

Preparation of hydrolysed test solutions (total saccharide compound): Weigh approximately 1 g of extract (pe2), Add 1 mL of 4N H2SO4. Heat under reflux for 2 hours. Neutralize with 1 N soda and transfer to a 20 mL volumetric flask. Adjust to 20 mL with water.

Preparation of non-hydrolysed test solutions (free saccharide compounds = monosaccharides): Weigh around 10 g of extract (pe3) in a 20 mL volumetric flask. Adjust to 20 mL with water

Dosage: the solutions are dosed according to the following table:

Shake then place for 5 minutes in a water bath at 100°C. Cool in an ice bath and make up to

10 mL with water. Measure the absorbance at 540 nm of the different solutions against the blank. Calculation :

Construct the calibration curve.

Deduce the concentration of total (QSRT) and free (QSRL) saccharide compounds, expressed as glucose, in the test solutions.

The titer in total saccharide compounds (TSRT) of the extract is given by the following formula:

Q _SRT x 100 x 20 TSRT (%) = pe ₂

With QSRT in mg/ml and pe ₂ in mg

The title in free saccharide compounds (TSRL) of the extract is given by the following formula:

Q _SRL X 100 x 20 TSRL (%) = pe ₃

With QS L in mg/ml and pe ₃ in mg

Method 6: Dosage of nitrogen compounds (amino acids, proteins)

The dosage of free amino acids and proteins can be carried out before or after hydrolysis by Ninhydrin spectrophotometry. The results are expressed as a percentage of amino acids relative to asparagine.

Dosage of total proteins and amino acids

Principle: Colorimetric determination of amino acids by the ninhydrin reagent after acid hydrolysis. The results are expressed as a percentage of total amino acids relative to asparagine.

Reagents

Citrate buffer (pH=5): Dissolve 2.1 g of citric acid in 20 ml of water, add 20 ml of 1 N sodium hydroxide and adjust to 50 ml with water.

Ninhydrin reagent: Dissolve 0.08 g of tin II chloride (SnCk, 2H2O) in 50 ml of citrate buffer (pH=5). Dissolve 2 g of ninhydrin in 50 ml of ethylene glycol monomethyl ether (EGME). Mix the two solutions.

Hydrochloric acid 6N: Dilute to 1/2 of concentrated hydrochloric acid (36%).

Diluent: Mix 100 ml of 1-propanol with 100 ml of water.

Preparation of solutions

Preparation of the standard range: Dissolve 17 mg of asparagine in 100 ml of water. Preparation of test solutions: Weigh approximately 30 to 200 mg of extract depending on the sample to be analyzed (pei) in a screw tube, add 2 ml of 6N HCl. Close hermetically then place for about 16 hours at 110°C. Neutralize with 3N sodium hydroxide (methyl red color change) then adjust to 20 ml with water.

Dosage:

Shake and place for 20 minutes in a water bath at 100°C. Cool in an ice bath. Adjust to 10 ml with diluent. Measure the absorbance at 570 nm of the different solutions against the blank.

Calculation :

Construct the calibration curve. Deduce the concentration of total amino acids (QAAT), expressed as asparagine, in the test solutions. The title in total amino acids (TAAT) of the extract is given by the following formula:

With QAAT in mg/ml and pei in mg

Method 7: Weight determination of chlorophylls

The chlorophyll content in the extract can be evaluated by the weight obtained after washing the extract with heptane. The extract is taken up in 10 volumes of methanol. After stirring for 15 min, the solution is filtered. The supernatant is dried and constitutes the fraction containing the chlorophylls.

Method 8: Determination of organic acids C.L.H.P

Principle: Dosage by C.L.H.P. organic acids from a plant extract. The organic acids assayed are: succinic, malic and ascorbic acids.

Chromatographic system:

- Column: Atlantis dd 8 5 pm 5 pm 250 x 4.6 mm Waters or equivalent;

- Temperature: 25°C;

- Mobile phase: Solvent A: 50 mM phosphate buffer pH 2.8; Solvent B: Acetonitrile; - Gradient: TO %A: 100%; 7.5 mins %A: 100%; 15 mins %A: 90%; 16 mins %A: 50%; 23 mins %A: 50%; 24 mins %A: 100%; 40 mins %A: 100%;

- Flow rate: 1 mL/min;

- λ = 200 to 400 nm (extraction at 214 nm);

- Injection volume: 5 pL.

Preparation of the solutions:

Control solution: Weigh 10 mg of control and dissolve in 20 mL of water. Perform the 1/5th, 1/10th and 1/20th dilutions.

Test solution: Weigh 250 mg of analyte into a 20 mL volumetric flask. Complete with water - Ultrasound if necessary.

Results: The chromatograms of the control and test solutions show several peaks of characteristic and identical spectra.

The cookie retention times are:

- Malic acid: 5.5 min,

- Ascorbic acid: 7.7 mins

- Succinic acid: 11.7 min.

Plot the calibration curves for each of the controls and deduce the quantity in the sample.

Method 9: Evaluation of color fastness on locks of white, natural, human hair after washing:

The staying power of a coloring composition according to the invention is evaluated by comparison with the staying power of a control composition (eg composition of the prior art).

In each case, 10 g of powder are mixed with 40 g of water before application to the wick.

The color fastness after washing is compared. All locks have undergone standardized washes up to 8 times with a neutral shampoo.

For each coloring composition, the color of 5 locks of human hair, natural white, color 10 (white) was measured using a reflectance colorimeter (Chromameter CR400, Minolta, France). The color parameters measured by this device, L*a*b*, make it possible to describe the color of the locks.

The evaluated parameter is a derivative of L*a*b, ie the color difference (dE*).

Where L1*, a-i*, bi* are the coordinates in the CIE LAB colorimetric space established in 1976 by the international commission on illumination of the first color to be compared and L2*, a2*, b2* those of the second.

The differences in coloration obtained are compared. Example 1: preparation of an extract of Sorghum bicolor (L.) Moench

100 g of dry and ground aerial parts (leafy stems) of Sorghum bicolor (L.) Moench are introduced into a reactor with 2 L of Ethanol/Water solvent; said solvent comprising 70% by volume of ethanol.

This mixture is stirred for 2 hours at room temperature.

The whole is filtered and the hydro-alcoholic filtrate is recovered then concentrated by evaporation of the ethanol.

The concentrate is then dried by lyophilization and the lyophilisate is finally ground to deliver a powder whose particle size is less than 250 μm.

The dry product thus obtained corresponds to the dry extract of Sorghum bicolor used in the context of the present invention and comprises 5% of apigeninidine by weight relative to the total weight of the dry extract.

The coloring intensity of this extract is between 100 and 200.

Example 2: preparation of a standardized extract of Sorghum bicolor (L.) Moench

100 g of dry and ground aerial parts of Sorghum bicolor (L.) Moench are introduced into a reactor with 2 liters of Ethanol/Water solvent; said solvent comprising 70% by volume of ethanol.

This mixture is stirred for 2 hours at room temperature.

The whole is filtered and the hydro-alcoholic filtrate is recovered then concentrated (removal of the alcohol). Maltodextrin is added to the aqueous concentrate, which is then dried by lyophilization and the lyophilisate is finally ground to deliver a powder whose particle size is less than 250 μm.

The dry product thus obtained corresponds to the standardized dry extract of Soghum bicolor according to the invention and comprises 3-4.5% of apigenidin.

The coloring intensity of this standardized extract is between 100 and 200.

Example 3: coloring efficacy on locks of hair of an extract of Sorghum bicolor (L.) Moench

In order to test the coloring efficacy of the same dry extract of Sorghum bicolor (L.) Moench, three concentrations are prepared, beforehand, by mixing the quantity of extract required with water (mass ratio 1/20 to preferably 1/10) at 50° C. or a thickening agent such as xanthan gum.

Each concentration is applied with a brush all along the lock of hair. Then the wick is placed at 50° C. for 50 minutes. The lock is then rinsed with hot water and the color intensity is measured.

A dose effect can be observed. preparation of a hydroalcoholic extract of Lawsonia inermis low in lawsone

50 g of crushed leaves of Lawsonia inermis are introduced into a reactor with 6 volumes of water. The paste obtained is stirred for 30 min at 50°C. Then, add 16 volumes of ethanol to this mixture, i.e. a final alcohol content of 80% v/v, then stir vigorously for 30 min. the whole is filtered (through an AF15 filter) and the hydroalcoholic filtrate is collected, sterilized and then concentrated by evaporation of the ethanol. The aqueous concentrate is then dried. The dry product corresponds to the dry henna extract (mass yield: 54%). The extract thus obtained comprises (% expressed by weight relative to the total weight of the dry extract):

- lawsone 0.6%;

- saccharide compounds: 69.9% (total sugars) (polysaccharide assay 59.3%);

- apigenin 0.05%;

- luteolin 0.17%. preparation of an aqueous extract of Lawsonia inermis low in lawsone

50 g of crushed leaves of Lawsonia inermis are introduced into a reactor with 6 volumes of water. The paste obtained is stirred for 30 min at 50°C. Shake vigorously for an additional 30 min. The whole is filtered (through an AF15 filter) and the aqueous filtrate is recovered, sterilized for 20 min at 120°C then concentrated. The aqueous concentrate is then dried. The dry product corresponds to the dry henna extract (mass yield: 60%).

The extract thus obtained comprises 0.4% lawsone, % expressed by weight relative to the total weight of the dry extract. extract preparation rich in lawsone

Example 6.1:

50 g of unground Lawsonia inermis leaves are extracted with 500 mL of water at 30-40°C for 30 min. To this solution, 600 mL of isopropyl acetate is added. The whole is mixed for 30 minutes. After decantation, the upper isopropyl acetate phase (480 mL) is recovered, the aqueous phase being discarded because it is practically devoid of lawsone. The isopropyl acetate phase is filtered and then put to dryness in a Rotavapor. The residue constitutes the dry extract of Henna

The plant contains 1.5 g of lawsone / 100 g dry plant.

The upper isopropyl acetate phase contains 80.7% of the lawsone potential present in the plant.

Henna dry extract contains 30.2% by weight of lawsone, i.e. 71% of lawsone present in the plant. Example 6.2:

49.5 g of unground Lawsonia inermis leaves are extracted with 500 mL of water at 30-40°C for 30 min. To this solution, 600 mL of isopropyl acetate is added. The whole is mixed for 30 minutes. After decantation, the upper isopropyl acetate phase is recovered, filtered through Büchner (K900) and the residue is rinsed with 50 mL of isopropyl acetate. The resulting solution is dried in a Rotavapor. The residue constitutes the dry extract of Henna The dry extract of Lawsonia inermis contains 30.9% by weight of lawsone.

Example 6.3:

50 g of unground Lawsonia inermis leaves are extracted with 500 mL of water at 30-40°C for 30 min. To this solution, 600 mL of ethyl acetate is added. The whole is mixed for 30 minutes. After decantation, the upper ethyl acetate phase is recovered, the aqueous phase being discarded because it is practically devoid of lawsone.

The quantity of lawsone in the ethyl acetate phase is determined by C.L.H.P and maltodextrin is added in sufficient quantity to obtain a mixture comprising 1.3% by weight of lawsone, which is then freeze-dried.

The dry extract of Lawsonia inermis standardized with maltodextrin contains 1.1% by weight of lawsone, i.e. 71% of lawsone present in the plant.

Example 6.4:

50 g of unground Lawsonia inermis leaves are extracted with 6 volumes of water at 30-40°C for 30 min. To this solution, 6 volumes of n-butanol is added at ambient temperature. The whole is mixed for 30 minutes. After decantation, the upper butanol phase is recovered, the aqueous phase being discarded because it is practically devoid of lawsone. The organic phase is concentrated with passage through water.

The lawsone content of the butanol phase is determined by H.P.L.C. and the maltodextrin is added in sufficient quantity to obtain a mixture containing between 1.1 and 1.3% by weight of lawsone.

The concentrate is dried to obtain a powder.

The extract includes the following compounds determined by UHPLC-UV: The presence of glycosilated luteolin, in particular luteolin-6-C-neohesperidoside, and coumaric acid is also observed.

Example 7: The coloring compositions are prepared by mixing an extract of the aerial parts of Sorghum bicolor (L.) Moench prepared according to examples 1 or 2 and an extract of the aerial parts of Lawsonia inermis prepared according to examples 4 or 5 Additional coloring agents can be added such as an extract of the aerial parts of Lawsonia inermis prepared according to Examples 6.1 to 6.4 or an extract of indigo plants.

The coloring compositions obtained provide intense coloring of keratin fibers.

Claims

48 CLAIMS

1. Method for preparing a coloring composition, in particular a coloring cosmetic composition for coloring keratin fibers, comprising the following steps:

- Obtaining the coloring composition.

2. Method of preparation according to claim 1, in which the first coloring agent has a coloring intensity varying from 90 to 200.

3. Method of preparation according to claim 1 or 2, in which the extract of the aerial parts of Sorghum bicolor (L.) Moench comprises from 0 to 10% by weight of water-soluble compounds relative to the total weight of the dry extract.

4. Method of preparation according to one of the preceding claims, in which the first coloring agent further comprises an inert carrier, thus forming a standardized extract of the aerial parts of Sorghum bicolor (L.) Moench.

5. Method of preparation according to one of the preceding claims, in which the extract of the aerial parts of Sorghum bicolor (L.) Moench is obtained by solid/liquid extraction, using an organic solvent chosen from alcohols, esters , ketones, ethers, chlorinated solvents or mixtures thereof or by means of a hydroalcoholic solution comprising at least 50% by volume of an alcohol miscible in water, aerial parts of Sorghum bicolor (L.) Moench. 49

6. Method of preparation according to one of claims 1 to 4 wherein the extract of the aerial parts of Sorghum bicolor (L.) Moench is obtained by a process comprising the following steps: a) agitation of the aerial parts of Sorghum bicolor in an organic solvent chosen from alcohols, esters, ketones, ethers, chlorinated solvents or mixtures thereof or in a hydroalcoholic solution comprising at least 50%, at least 60%, at least 70%, at least 80% or even at at least 90% by volume of a water-miscible alcohol; b) liquid/solid separation; c) recovery of the liquid phase; d) concentration of the liquid phase obtained in step c) and elimination of the alcohol; e) possibly drying.

7. Method of preparation according to one of the preceding claims, in which the extract of the aerial parts of Lawsonia inermis is obtained by an aqueous, hydroalcoholic or alcoholic extraction of the aerial parts of Lawsonia inermis.

8. Method of preparation according to one of the preceding claims, in which the extract of the aerial parts of Lawsonia inermis comprises at least 60% by weight, preferably at least 65% by weight or at least 70% by weight of saccharide compounds per relative to the total weight of the dry extract.

9. Method of preparation according to one of the preceding claims, in which an additional coloring agent derived from dyeing plants is provided, said additional coloring agent being a powder or an extract of dyeing plants chosen from Lawsonia inermis, indigo plants, red pigment source plants, red or purple to black pigment source plants, yellow pigment source plants, red to bluish green pigment source plants, tannin source plants, brown pigment source plants and combinations thereof.

10. Method of preparation according to claim 9, in which the additional coloring agent is an extract of Lawsonia inermis comprising from 7 to 60% by weight of lawsone relative to the total weight of the dry extract.

11. Method of preparation according to claim 9, in which the additional coloring agent is an extract of Lawsonia inermis comprising from 7 to 60% by weight of lawsone obtained by a process comprising the following steps: 50 a) maceration of the aerial parts of Lawsonia inermis in water, carried out at a pH between 4 and 8, during which the glycosylated derivatives of lawsone, such as hennosides, initially present in the aerial parts of Lawsonia inermis are partially or totally hydrolyzed enzymatically, resulting in the production of an aqueous solution containing lawsone; b) addition of an organic solvent to the aqueous solution obtained at the end of step a), the organic solvent being chosen from linear or branched C4-C12 alcohols and solvents in which the miscibility of water is less than 10%, or even less than 5% by weight at 25° C., resulting in the formation of an aqueous phase and an organic phase; c) recovery of the organic phase obtained at the end of step b); d) concentration of the organic phase recovered at the end of step c); and e) optionally drying.

12. Method of preparation according to claim 9, in which the additional coloring agent is an extract of indigo plants, the indigo plants being chosen from indigo (Indigofera tinctoria), dyer's knotweed (Polygonum tinctorium or even Persicaria tinctoria) , dyers' pastel (Isatis tinctoria L.), Couroupita guianensis (in Anglo-Saxon: Cannon ball tree), wild indigo (Baptisia tinctoria), dyers' croton (Chrozophora tinctoria), dyers' laurel (Wrightia tinctoria), indigo-vine (Philenoptera cyanescens = Lonchocarpus cyanescens), L. laxiflorus (Lonchocarpus laxiflorus), Marsdénia tinctoria (Asclepiadaceae), Assam indigo (Strobilanthes cusia or even Strobilanthes flaccidifolius) and combinations thereof.

13. Coloring composition, in particular coloring cosmetic composition for coloring keratin fibers, obtainable according to the method of one of claims 1 to 12.

14. Cosmetic method for dyeing keratin fibers comprising the application to the keratin fibers of an aqueous composition comprising a dye composition according to claim 13.

15. Cosmetic method for dyeing keratin fibers according to claim 14, comprising the following steps: a) providing a dye composition according to claim 13, in particular in dry form, in particular in powder form; b) preparation of an aqueous composition by adding water to the coloring composition at a temperature ranging from 20 to 98° C.; c) application of the aqueous composition to the keratin fibres; d) optional heating of the keratin fibres; e) rinsing.