EP1367983A1

EP1367983A1 - Microcapsules with aqueous core containing oxidation-reduction enzymes and their use in oxidation dyeing compositions

Info

Publication number: EP1367983A1
Application number: EP02708419A
Authority: EP
Inventors: Anne-Laure Bernard; Luc Nicolas Morgantini; Bruno Biatry; Jean-Thierry Simonnet
Original assignee: LOreal SA
Current assignee: LOreal SA
Priority date: 2001-03-05
Filing date: 2002-02-27
Publication date: 2003-12-10
Also published as: FR2821548A1; FR2821548B1; WO2002069922A1

Abstract

The invention concerns microcapsules with aqueous core containing at least an oxidation-reduction enzyme selected among the oxidoreductases with 2 electrons, the oxidoreductases with 4 electrons and the peroxidases, and with a polymer coating consisting of at least a polymer selected among polycaprolactone, poly(3-hydroxybutyrate), poly(ethylene adipate), poly(butylene adipate), cellulose esters and at least a C1-C4 carboxylic acid, styrene and maleic anhydride copolymers, styrene and acrylic acid copolymers, styrene-ethylene/butylene-styrene block terpolymers, styrene-ethylene/propylene-styrene block terpolymers, and ethylene, vinyl acetate and maleic anhydride terpolymers. The invention also concerns a method for preparing said microcapsules and oxidation dyeing compositions containing same.

Description

Microcapsules with an aqueous core containing redox enzymes and their use in oxidation dye compositions

The present invention relates to microcapsules with an aqueous core containing, in a polymeric envelope, at least one redox enzyme, a process for the preparation of these microcapsules as well as oxidation dye compositions containing them.

The use of redox enzymes in place of chemical oxidizing agents such as hydrogen peroxide in the oxidation dye of keratin fibers has been known for a long time. Its main advantage is that it allows coloring of the fibers under milder conditions and preserving the structure of the keratin fibers.

Enzymatic oxidation dyeing, however, presents a number of problems. Indeed, the enzyme tends to adsorb on the keratinous substrate and not to be completely eliminated during rinsing which can pose safety problems.

Certain dyes or dye precursors can inhibit or deactivate the enzyme and thus reduce the intensity and quality of the colorings obtained. Furthermore, enzymes, which are complex biological molecules, are sensitive to certain factors in their immediate environment and in particular to heat.

The Applicant has discovered that it is possible to solve the problems described above by encapsulating the redox enzymes commonly used in oxidation tincture in particular microcapsules with an aqueous core and a polymeric envelope.

The present invention therefore relates to microcapsules with a polymeric envelope, the composition of which will be described in more detail below, and with an aqueous core containing at least one chosen redox enzyme. among the 2-electron oxidoreductases, the 4 electron oxidoreductases and peroxidases.

The invention also relates to anhydrous microcapsules obtained by dehydration of the microcapsules with an aqueous core above.

The invention also relates to a process for the preparation of these microcapsules with a polymeric envelope and an aqueous core containing at least one redox enzyme chosen from 2-electron redoxases, 4-redox reductases and peroxidases, by multiple emulsification.

A subject of the invention is also compositions for the oxidation dyeing of keratin fibers such as the hair, containing, in a physiologically acceptable medium, a) at least one oxidation dye precursor chosen from oxidation bases and / or the couplers, and b) microcapsules with a polymeric envelope, the composition of which will be described in more detail below, and with an aqueous core containing at least one redox enzyme chosen from 2-electron redoxases, the 4-electron oxidoreductases and peroxidases.

A further subject of the invention is a multicomponent oxidation dye kit comprising at least a first component containing the microcapsules with an aqueous core and with a polymeric envelope described above, and at least a second component containing at least one dye precursor d oxidation chosen from oxidation bases and / or couplers, the two components being kept separately and intended to be mixed with each other immediately before application to the keratin fibers.

The invention also relates to a process for dyeing keratin fibers and in particular the hair, using the oxidation dye compositions or the oxidation dye kit described above. The primary effect of encapsulating the enzyme is the physical separation between the enzyme and the biological substrate such as the hair and scalp. This separation prevents the adsorption of enzymes, improves the efficiency of rinsing and increases the safety of the system. Isolation of the enzyme also prevents it from being inhibited by certain dyes.

The Applicant has also found that the encapsulation of the redox enzyme makes it possible to considerably reduce its inactivation by heat. Indeed, the stability of the encapsulated enzyme, stored at a temperature between 25 and 45 ° C, is on average about 2 times greater than that of the same non-encapsulated enzyme stored under the same temperature conditions.

The process for preparing the microcapsules of the present invention gives excellent rates of enzyme encapsulation. Indeed, the degree of encapsulation, defined as the ratio of the amount of enzyme found inside the microcapsules to the total amount of enzyme used, is generally greater than or equal to 90%.

Another advantage of the microcapsules of the present invention is the irreversibility of the encapsulation of the redox enzymes. Indeed, the latter, because of their large molecular weight, cannot pass through the polymeric envelope of the microcapsules and are consequently not released into the external medium of the oxidation dye composition. The Applicant has also found that even drying (for example by lyophilization) followed by redispersion of the microcapsules did not cause the release of the encapsulated enzymes.

The polymeric envelope of the microcapsules of the present invention is therefore capable of effectively retaining proteins while letting through diffusion, molecules of low molecular weight such as oxygen or oxygen peroxide dissolved in the external aqueous medium and / or interior.

This selective permeability of the envelope, essential for the use of the oxidation-reduction enzymes encapsulated in oxidation dye of the hair, can be attributed to the moderately hydrophobic nature of the polymers used which are, admittedly, insoluble in water but do not constitute a barrier perfectly sealed against the aqueous phase and the low mass solutes it contains.

The envelope of the microcapsules of the present invention consists of at least one polymer chosen from “polycaprolactone,

• poly (3-hydroxybutyrate),

• poly (ethylene adipate),

• poly (butylene adipate),

• cellulose esters and at least one Cj carboxylic acid. , such as cellulose acetate, cellulose propionate and cellulose butyrate, preferably mixed cellulose esters of two types of carboxylic acids, such as cellulose acetoprionate or cellulose acetobutyrate,

• copolymers of styrene and maleic anhydride, • copolymers of styrene and acrylic acid,

• styrene-ethylene / butylene-styrene block terpolymers,

• styrene-ethylene / propylene-styrene block terpolymers, and

• terpolymers of ethylene, vinyl acetate and maleic anhydride.

The redox enzyme (s) encapsulated in the aqueous core of the microcapsules of the present invention are chosen from

• 2-electron oxidoreductases,

• 4-electron oxidoreductases and

• peroxidases.

The oxidoreductase (s) with 2 electrons encapsulated according to the present invention are in particular chosen from pyranose oxidases, glucose oxidases, glycerol oxidases, lactate oxidases, pyruvate oxidases, uricases, choline oxidases, sarcosine oxidases, bilirubin oxidases and amino acid oxidases.

The oxidized reductases with 2 encapsulated electrons are preferably chosen from uricases of animal, microbiological or biotechnological origin. By way of example, mention may be made of uricase extracted from boar liver, the uricase of Arthrobacter globiformis, as well as the uricase of Aspergillus flavus.

The 2-electron oxidoreductase (s) can be used in pure crystalline form or in a diluted form in an inert diluent for said 2-electron oxidoreductase.

Each oxidoreductase with 2 electrons needs, in order to be able to catalyze the oxidation reaction of oxygen to H ₂ O ₂ , the presence of a donor for said enzyme.

According to the invention, the term “donor” is understood to mean the various substrates also necessary for the functioning of said one or more 2-electron oxidoreductases. The nature of the donor for said enzyme varies depending on the nature of the 2-electron redoxase which is used. For example, as a donor for pyranose oxidases, mention may be made of D-glucose, L-sorbose and D-xylose; as a donor for glucose oxidases, mention may be made of D-glucose; as a donor for the glycerol oxidases, mention may be made of glycerol and dihydroxyacetone; as lactate oxidase donors, there may be mentioned lactic acid and its salts; as the donor for pyruvate oxidases, mention may be made of pyruvic acid and its salts; as a sleeper for uricases, mention may be made of uric acid and its salts; as a donor for the choline oxidases, mention may be made of choline and its addition salts of an acid such as choline hydrochloride, and betaine aldehyde; as a donor for sarcosine oxidases, mention may be made of sarcosine, N-methyl-L-leucine, N-methyl-DL-alanine, and N-methyl-DL-valine; and finally, as a donor for bilirubin oxidases, mention may be made of bilirubin.

The donor is not necessarily encapsulated with the enzyme. It is preferably added in the cosmetic medium outside the microcapsules. It then diffuses through the polymeric membrane microcapsules towards the interior of these where it is transformed under the combined effect of the enzyme and oxygen. If the donor is encapsulated with the enzyme, it is clear that the the enzyme microcapsules must be packaged away from oxygen (for example in an aerosol device), the reaction for the formation of hydrogen peroxide only taking place after being brought into contact with the oxygen of the air. The hydrogen peroxide formed during this reaction diffuses in the opposite direction from the inside of the microcapsules to the outside environment where it can play the role of oxidizing agent for oxidation dye precursors.

The oxidized reductase (s) with 4 electrons encapsulated according to the present invention are in particular chosen from laccases, tyrosinases, catechol oxidases and polyphenol oxidases.

The coloring can be carried out by diffusion of the dye precursors through the polymeric envelope towards the interior of the microcapsules followed by the backscattering of the oxidized dyes, or else by means of a mediator.

The laccases can in particular be chosen from laccases of plant origin, of animal origin, of fungal origin (yeasts, molds, fungi) or of bacterial origin, the organisms of origin being able to be mono- or multicellular. Laccases can also be obtained by biotechnology.

Among the laccases of plant origin which can be used according to the invention, mention may be made of laccases produced by plants carrying out chlorophyll synthesis such as those indicated in patent application FR-A-

2,694,018.

Mention may in particular be made of the laccases present in the extracts of Anacardiaceae such as for example the extracts of Magnifera indica, of Schinus molle or of Pleiogynium timoriense; in extracts from

Podocarpaceae; from Rosmarinus off .; Solanum tuberosum; Iris sp. from Coffea sp. Daucus carrota; of Vinca minor; Persea amerîcana from Catharenthus roseus; from Musa sp .; Malus pumila; Gingko biloba; of Monotropa hypopithys (sucepin), ά'Aesculus sp. Acer pseudoplatanus; of Prunus persica and Pistacia palaestina.

Among the laccases of fungal origin, possibly obtained by biotechnology, which can be used according to the invention, mention may be made of the laccase (s) obtained from Polyporus versicolor, Rhizoctonia pratola and Rhus vernicifera as described for example in patent applications FR A-2112549 and EP-A-504005; the laccases described in patent applications WO 95/07988, WO 95/33836, WO 95/33837, WO 96/00290, WO 97/19998 and WO 97/19999, the content of which forms an integral part of the present description as well as by example laccase (s) from Scytalîdium, Polyporus pinsitus, Myceliophtora thermophila, Rhizoctonia solani, Pyricularia orizae, and their variants. Mention may also be made of the laccase (s) from Trametes versicolor, Fomes fomentarius, Chaetomium thermophile, Neurospora crassa, Colorius versicol, Botrytis cinerea, Rigiάoporus lignosus, Phellinus noxius, Pleurotus ostreatus, Aspergillus nidulans, of Podospora anserina, to Agaricus bisporus, of Ganoderma lucidum, of Glomerella cingulata, of Lactarius piperatus, of Russula delica, of Heterobasidion annosum, of Thelephora terrestris, of Cladosporium cladosporioides, of Cerrena unicolor, of Coriolus hirsut Coprinus cinereus, Panaeolus papilionaceus, Panaeolus sphinctrinus, Schizophyllum commune, Dichomitius squalens, and their variants.

More preferably, laccases of fungal origin, possibly obtained by biotechnology, will be chosen.

The mediators can for example be chosen from the compounds of formula

in which

- A and A ₂ , identical or different, each represent

(a) a saturated or unsaturated, linear or branched aliphatic radical comprising from 1 to 30 carbon atoms, optionally substituted by one or more hydroxyl, halogeno, sulfo, carboxy, nitro or phenyl radicals;

(b) a heterocyclic radical comprising from 1 to 4 heteroatoms and from 5 to 10 members optionally substituted by one or more CC, halo, phenyl, hydroxyl, or C ₇ aralkyl radicals -

(c) an aromatic radical comprising from 6 to 10 members, optionally substituted by one or more C 1 -C 6 alkyl, halo, sulfo, carboxy, nitro, hydroxyl or nitroso radicals; the nitrogen atom of the NX group can form with the groups Aι- (CO) _n and A ₂ - (CO) _p a heterocycle comprising from 5 to 18 members, said heterocycle possibly or not. be substituted by one or more C ₁ -C ₄ alkyl, hydroxyl, phenyl, halogen, sulfo, carboxy or nitro radicals;

- X represents a group -OH, = 0, = S, -> 0 or -> S;

- m, n and p, independently of each other, are whole numbers equal to 0 or 1.

Among the enzymatic mediators corresponding to the above formula, mention may especially be made of hydroxylamine, N, N-dipropylhydroxylamine, N, N-diisopropylhydroxylamine, phenylhydroxy lamine, N-acetylhydroxylamine, 1-phenyl-1H- 1,2,3-triazole-1-oxide, 2,4,5-triphenyl-2H-1,2,3-triazol-l-oxide, 1-hydroxybenzotriazole, 1-hydroxybenzotriazole-sulfonic acid, 1- hydroxybenzimidazole, N-hydroxyphthalimide, N-hydroxysuccinimide, quinoline-N-oxide, isoquinoline-N-oxide, 1-hydroxypiperidine, violuric acid, 4-hydroxy-3-nitrosocoumarin, 1,3-dimethyl-5-nitrosobarbituric acid, l-nitroso-2-naphthol, 2-nitroso-l-naphtol-4-sulfonic acid, 2-nitroso-l-naphtol, l-nitroso acid -2-naphthol-3,6-disulfonic acid and 2,4-dinitroso-1,3-dihydroxybenzene. The enzyme mediator (s) can also be chosen from syringic acid and its esters; acetosyringone; syringaldehyde; parahydroxycinnamic acid; vanillin; 7-hydroxycoumarin; 2,4-dichlorophenol; parahydroxybenzènesulfonate; 2,2'-azino-bis ~ (3-ethyl-benzothiazoline-6-sulfonate); phenothiazines such as 10-methyl phenothiazine; benzidines such as 3,3'-dimethylbenzidine; amino derivatives of 2-naphthalene sulfonic acid; L-tyrosine; ferulic acid; caffeic acid; chlorogenic acid; and sinapic acid.

The mediator will either be encapsulated with the enzyme or added to the cosmetic medium outside the microcapsules. In the first case, the microcapsules must of course be kept away from air.

The peroxidase (s) encapsulated in the microcapsules according to the present invention can in particular be chosen from the enzymes belonging to subclass 1.11.1 described in the work Enzyme

Nomenclature, Académie Press Inc., 1984. Some of them require the presence of a donor to function.

This is the case, in particular for NADH peroxidases (1.11.1) [donor =

NADH], fatty acids peroxidases (1.11.1.3) [donor = fatty acid, for example palmitate], NADPH peroxidases (1.11.1.2), [donor = NADPH], cytochrome-C peroxidases (1.11.1.5) [donor = ferrocytochrome C], iodide peroxidases (1.11.1.8) [donor = iodide], chlorides peroxidases (1.11.10) [donor = chloride], L-ascorbates peroxidases (1 .11.1.11) [donor = L- ascorbate], glutathione peroxidases (1.11.1.9) [donor = glutathione].

Other peroxidases work without a donor other than the oxidation dye. This is the case for catalases (1.11.1.6) and simplex peroxidases

(1.11.1.7).

All peroxidases work in the presence of hydrogen peroxide which is supplied as is by adding it to the cosmetic medium. externally or generated in situ by the enzymatic route, for example by a co-encapsulated 2-electron oxidases, such as those described above, • in the presence of a donor and of oxygen.

The peroxidases used can be of plant, animal, fungal or bacterial origin. They can also be obtained by biotechnology.

Thus, peroxidases can for example be obtained from apple, apricot, barley, black radish, beet, cabbage, carrot, corn, cotton, garlic, grapes, mint, rhubarb, soy, spinach, coprin, bovine milk, microorganisms such as Acetobacter peroxidans, Staphylococcus faecalis, Arthromyces ramosus.

In the same way as for 4-electron oxidoreductases, the oxidation coloring in the presence of peroxidases can be done by diffusion of the dye precursors through the envelope towards the inside of the microcapsules and backscattering of the oxidized dyes, or else by through a mediator chosen from those described above.

Among the redox enzymes described above, very particularly preferred are the 2-electron redoxases, and among them the uricase. Uricase catalyzes the transformation of uric acid into allantoin in the presence of oxygen, this reaction releasing hydrogen peroxide.

The amount of enzyme in the microcapsules according to the present invention can be expressed either in terms of amount of protein or in terms of enzymatic activity.

The microcapsules with a polymeric shell and an aqueous core of the present invention preferably contain from 1 to 30% by weight, and in particular from 2 to 20% by weight of redox enzyme, relative to the total weight of the microcapsules (shell + internal aqueous phase + enzyme). When using dehydrated microcapsules, the redox enzyme preferably represents from 2 to 95%, and in particular from 5 to 70% of the total weight of the dehydrated microcapsules.

The enzymatic activity of the microcapsules with a polymeric envelope and an aqueous core of the present invention is measured according to methods specific to the encapsulated enzyme and expressed in specific units.

Thus, the enzymatic activity of microcapsules containing oxidoreductases with 2 electrons, and in particular uricase, is determined by oximetry using an oxy graph from the company Hansutech.

One unit of 2-electron oxidoreductase U corresponds to the quantity of enzyme - or of microcapsules containing the enzyme - catalyzing the formation of 1 μmole of H ₂ 0 ₂ per minute at a pH of 8.5 and at a temperature of 25 ° C.

The microcapsules with a polymeric envelope and an aqueous core of the present invention preferably have an enzymatic activity of oxidoreductase with 2 electrons of between 500 and 10,000 U / g of microcapsules, preferably between 1000 and 5000 U / g of microcapsules. .

The aqueous core of the microcapsules, that is to say the encapsulated internal aqueous phase of the primary water-in-oil emulsion in which the redox enzyme is found, may also contain, in the dissolved state, one or more water-soluble polymers and / or one or more low molecular weight polyols. The role of water-soluble polymers is to stabilize the primary emulsion. Polyols have the function of stabilizing the active ingredient by reducing the water activity of the encapsulated internal aqueous phase.

The water-soluble polymers are chosen in particular from poly (vinyl alcohol), polyvinylpyrrolidone, carboxymethylcellulose, poly (carboxylic acid) and crosslinked derivatives thereof, and natural gums such as xanthans, starch, sodium alginate, pectins, chitosan, guar, carob and carrageenan. These polymers water-soluble may be present in an amount of 0.01 to 10%, preferably in an amount of 0.1 to 5% by weight relative to the total weight of the encapsulated internal aqueous phase.

The low molecular weight polyols are chosen, for example, from glycerol and C ₃ -C ₅ alkylene glycols, in particular propylene glycol and pentylene glycol, and can be present in a proportion of 10% to 90% by weight, preferably in the proportion of 10 to 50% by weight relative to the total weight of the encapsulated internal aqueous phase.

The size and internal structure of the microcapsules depends on a very large number of parameters linked to the manufacturing process, such as the temperature, the stirring speed during emulsification, the chemical nature and the respective amounts of the various water-soluble components. and organosoluble, the amount of stabilizers etc. Those skilled in the art will know how to vary these different parameters to obtain the morphology of microcapsules sought.

The microcapsules can in particular be univacuolar or multivacuolar, that is to say the external envelope can contain a single compartment of aqueous phase or else the internal aqueous phase can be divided into a multitude of compartments separated by walls of the same nature. chemical than the outer shell. This phenomenon generally occurs when the multiple emulsion is particularly stable and gives excellent encapsulation results. .

The weight ratio of the encapsulated internal aqueous phase forming the core of the microcapsules of the present invention to the wall thereof is generally between 0.1 / 1 and 50/1 and preferably between 0.5 / 1 and 10 / 1.

The microcapsules of the present invention generally have an average diameter of between 0.5 μm and 500 μm and more particularly between 1 μm and 100 μm. The present invention also relates to a method for manufacturing microcapsules with an aqueous core containing at least one redox enzyme and with a polymeric envelope as described above. This process is a microencapsulation process by multiple emulsion - solvent evaporation comprising the following successive steps:

(a) solubilization or dispersion in an aqueous phase of at least one redox enzyme chosen from 2-electron redoxases, 4-redox reductases and peroxidases,

(b) emulsification of the aqueous solution or dispersion obtained in step (a) in a solution of at least one polymer chosen from polycaprolactone, poly (3-hydroxybutyrate), poly (ethylene adipate), the esters of cellulose and at least one C _1-4 carboxylic acid, preferably mixed cellulose esters of two types of carboxylic acids, poly (butylene adipate), copolymers of styrene and maleic anhydride, copolymers of styrene and acrylic acid, styrene-ethylene / butylene-styrene block terpolymers, styrene-ethylene / propylene-styrene block terpolymers, and terpolymers of ethylene, vinyl acetate and maleic anhydride, in a solvent organic immiscible with water,

(c) emulsification of the primary water-in-oil emulsion obtained in step (b) in an aqueous solution preferably containing an emulsion stabilizing agent,

(d) elimination of the organic solvent by evaporation giving an aqueous suspension of microcapsules, and optionally

(e) partial or total elimination of water.

In a preferred embodiment of the invention, step (e) consists of dehydration of the microcapsules giving a powder of microcapsules. The encapsulation of redox enzymes in this anhydrous form increases the stability of the enzymes compared to an encapsulation in microcapsules having retained their internal aqueous phase.

The water-immiscible organic solvent used in step (b) is generally chosen according to its solvent power with respect to the material. of the wall, its water solubility which must be as low as possible and its. boiling point which is preferably less than 100 _. ° C. Dichloromethane, cyclohexane, heptane, 1-chloro-butane and ethyl acetate can be used, for example.

The stability of the multiple emulsion is a determining factor for obtaining good encapsulation results. Indeed, insufficient stability of the multiple emulsion would cause a mixture of the internal and external aqueous phases and a leakage of the enzyme out of the vesicles formed. It is therefore strongly recommended to add to the continuous aqueous phase of step (c) an emulsion stabilizing agent.

Suitable polymeric stabilizers are known in the art and can be chosen, for example, from polyvinyl alcohol, polyvinylpyrrolidone, water-soluble styrene-maleic anhydride copolymers, carboxymethylcellulose, starch, chitosan and polyacrylic acid.

Although the use of a polymeric stabilizing agent is preferable, water-soluble surfactants can also be used in place of it.

It is also possible to introduce into the organic solvent solution of step (b) a surfactant in order to improve the stability of the primary emulsion. A person skilled in the art will know how to choose the appropriate compound, for example surfactants of HLB (hydrophilic-lipophilic balance) of less than 10, such as sorbitan and fatty acid esters such as, for example, polysorbates, lecithins. soluble, fatty acid monoglycerides, PEG-30 dipolyhydrostearate (Arlacel ^® PI 35 of ICI), cetyl dimethicone copolyol (Abil ^® EM90 society GOLDSCH- MIDT) and oxyethylenated polydimethylsiloxane (DC2-5695 ^® of DOW CHEMICAL). The suspension of microcapsules obtained after evaporation of the organic solvent can be incorporated as such in a dye composition. If desired, the microcapsules can also be isolated from the aqueous suspension obtained in step (d) by filtration and they can be dried for example by evaporation or lyophilization so as to obtain a powder of microcapsules, which can then be resuspended in an aqueous medium or in a dye composition.

The present invention also relates to an oxidation dye composition containing, in a physiologically acceptable medium, at least one oxidation dye precursor chosen from oxidation bases and / or couplers, and an appropriate quantity of microcapsules. described above with a polymeric envelope and an aqueous core containing at least one redox enzyme chosen from 2-electron redoxases, 4-redox reductases and peroxidases.

The microcapsules preferably represent from 0.01% to 50%, and in particular from 0.1 to 30% of the total weight of the oxidation dye composition.

As indicated above, the oxidation dyes which can be used in the oxidation dye compositions of the present invention are chosen from oxidation bases and / or couplers.

Preferably, the oxidation dye compositions according to the invention contain at least one oxidation base.

The oxidation bases which can be used in the oxidation dye compositions of the present invention are chosen from those conventionally known in oxidation dyeing. Mention may in particular be made of ortho- and para-phenylenediamines, double bases, ortho- and para-aminophenols and heterocyclic bases below, as well as their acid addition salts.

We can cite in particular: (I) The para-phenylenediamines of formula (I) and their acid addition salts:

in which:

Ri represents a hydrogen atom, a C ₁ -C ₄ alkyl radical, CC ₄ monohydroxyalkyl, C ₂ -C ₄ polyhydroxyalkyl, alkoxy (Cι-C ₄ ) - alkyl (Cι-C ₄ ), C alkyl ₁ -C ₄ substituted by a nitrogen, phenyl or 4'-aminophenyl group; R ₂ represents a hydrogen atom, a Cι -C alkyl radical, C1-C ₄ monohydroxyalkyl or C ₂ -C ₄ polyhydroxyalkyl, (Cι-C ₄ ) alkoxy (Cι-C) alkyl or C ₁ alkyl -C ₄ substituted by a nitrogen group; or

Ri and R ₂ form, with the nitrogen atom which carries them, a 5 or 6-membered nitrogen heterocycle optionally substituted by one or more alkyl, hydroxy or ureido groups;

R ₃ represents a hydrogen atom, a halogen atom such as a chlorine atom, a CC ₄ alkyl radical, sulfo, carboxy, CC ₄ monohydroxyalkyl or C1-C ₄ hydroxy alkoxy, C ₁ acetylaminoalkoxy -C ₄ , C ₁ -C ₄ mesylaminoalkoxy or carbamoylaminoalkoxy C _r C ₄ , R ₄ represents a hydrogen or halogen atom or a C ₁ -C ₄ alkyl radical.

Among the nitrogen groups of formula (I) above, there may be mentioned in particular the amino, monoalkyl (Cι-C ₄ ) amino, dialkyl (Cι-C ₄ ) amino, trialkyl (CC ₄ ) amino, monohydroxyalkyl (CrC) radicals ₄ ) amino, imidazolinium and ammonium.

Among the paraphenylenediamines of formula (I) above, there may be mentioned more particularly paraphenylenediamine, paratoluylenediamine, 2-chloroparaphenylenediamine, 2,3-dimethyl-paraphenylenediamine, 2,6-dimethylparaρhenylenediamine, 2,6-diethyl-paraphenylenediamine, 2,5-dimethylparaphenylenediamine, N, N-dimethyl-paraphenylenediamine, N, N-diethylparaphenylenediamine, N, N-diproρyl-paraphenylenediamine, 4- amino-N, N-diethyl-3-methyl-aniline, N, N-bis- (β-hydroxyethyl) - paraphenylenediamine, 4-N, N-bis- (β-hydroxyethyl) amino-2-methyl-aniline , 4-N, N-bis- (β-hydroxyethyl) -amino-2-chloro-aniline, 2-β-hydroxyethyl- paraphenylenediamine, 2-fluoro-paraphenylenediamine, 2-isopropyl- paraphenylenediamine, N- (β-hydroxypropyl) -paraphenylenediamine, 2-hydroxymethyl-paraphenylenediamine, N, N-dimethyl-3-methylpara- phenylenediamine, N, N- (ethyl-β-hydroxyethyl) -paraphenylenediamine,

N- (β, γ-dihydroxypropyl) -paraphenylenediamine, N- (4'-aminophenyl) - paraphenylenediamine, N-phenyl-paraphenylenediamine, 2-β- hydroxyethyloxy-paraphenylenediamine, 2-β-acetylaminoethylenediamine N- (β-methoxyethyl) paraphenylenediamine, 2-methyl-1-N-β-hydroxyethyl-paraρhenylenediamine, and their acid addition salts.

Among the para-phenylenediamines of formula (I) above, very particularly preferred is paraphenylenediamine, paratoluylenediamine, 2-isopropylparaphenylenediamine, 2-β-hydroxyethyl-paraphenylenediamine, 2-β-hydroxyethyloxy-paraphenylenediamine, 2, 6-dimethyl- paraphenylene diamine, 2,6-diethyl-paraphenylenediamine, 2,3-dimethyl- paraphenylenediamine, N, N-bis- (β-hydroxyethyl) -paraphenylenediamine, 2-chloro-paraphenylenediamine, and their acid addition salts.

(II) According to the invention, the term “double bases” is understood to mean compounds comprising at least two aromatic rings to which amino and / or hydroxyl groups are attached.

Among the double bases which can be used as oxidation bases in the dye compositions in accordance with the invention, mention may in particular be made of the compounds corresponding to the following formula (II), and their acid addition salts:

in which

- Zι and Z ₂ , identical or different, represent a hydroxyl radical or - NH ₂ optionally substituted by a C ₁ -C ₄ alkyl radical or by a connecting arm Y;

- the link arm Y represents an alkylene chain comprising from 1 to 14 carbon atoms, linear or branched, optionally interrupted or terminated by one or more nitrogen groups and / or by one or more heteroatoms such as oxygen and sulfur atoms or nitrogen, and optionally substituted with one or more hydroxyl or Cι-C ₆ alkoxy radicals;

- R ₅ and R ₆ independently represent a hydrogen or halogen atom, an alkyl radical in C ₁ -C ₄ monohydroxyalkyl, C ₁ -C ₄ polyhydroxyalkyl, C ₂ -C ₄ aminoalkyl, C ₁ -C ₄ or a link arm

Y;

- R ₇ , Rg, R ₉ , Rio, Rn and R ₁ 2, identical or different, represent a hydrogen atom, a linker Y or a C ₁ -C ₄ alkyl radical; it being understood that the compounds of formula (II) have only one linker arm Y per molecule.

Among the nitrogen groups of formula (II) above, there may be mentioned in particular the amino, monoalkyl (Cι-C ₄ ) amino, dialkyl (Cj- C ₄ ) amin 0, trialkyl (Cι-C ₄ ) amin 0 radicals , monohydroxyalkyl (Cι-C ₄ ) amino, imidazolinium and ammonium.

Mention may more particularly be made, among the double bases of formulas (II) above, of N, N'-bis- (β-hydroxyethyl) -N, N'-bis- (4'-aminophenyl) - 1,3-diamino-propanol, N, N'-bis- (β-hydroxyethyl) -N, N'-bis- (4'-aminophenyl) -ethylenediamine, N, N'-bis- (4 -aminophenyl) -tetramethylenediamine, N, N '- bis - (β-hy droxy ethyl) -N, N'-bis- (4-aminophenyl) -tetramethylene-diamine, N, N'-bis- (4- methyl-aminophenyl) -tetramethylenediamine, N, N'- bis- (ethyl) -N, N'-bis- (4'-amino-3'-methylphenyl) -ethylenediamine, 1,8-bis-

(2,5-diaminophenoxy) -3,5-dioxaoctane, and their acid addition salts.

Among these double bases of formula (II), N, N'-bis- (β-hydroxyethyl) - N, N'-bis (4'-aminophenyl) - l, 3-diamino-propanol, l, 8- bis- (2,5-diaminophenoxy) -3,5-dioxaoctane or one of their acid addition salts are particularly preferred.

(III) para-aminophenols corresponding to the following formula (III), and their addition salts with an acid:

in which

Rι ₃ represents a hydrogen atom, a halogen atom such. ue fluorine, a C ₁ -C ₄ alkyl radical, C1-C ₄ monohydroxyalkyl, (Cι-C ₄ ) alkoxy (Cι-C) alkyl or C ₁ -C ₄ aminoalkyl, or hy droxy alkyl (Cι-

C) C ₁ -C ₄ aminoalkyl.

R ₁₄ represents a hydrogen atom or a halogen atom such as fluorine, an alkyl radical in C ₁ -C ₄ monohydroxyalkyl, C 1 -C ₄ polyhydroxyalkyl, C ₂ -C ₄ aminoalkyl, C ₁ -C ₄ , C ₁ -C ₄ cyanoalkyl or alkoxy (Cι-C ₄ ) -alkyl (C _r C4).

Among the para-aminophenols of formula (III) above, there may be mentioned more particularly para-aminophenol, 4-amino-3-methyl-phenol, 4-amino-3-fluoro-phenol, 4-amino -3-hydroxymethyl-phenol, 4-amino-2- methyl-phenol, 4-amino-2-hydroxymethyl-phenol, 4-amino-2- methoxymethyl-phenol, 4-amino-2-aminomethyl-phenol, 4-amino-2- (β- hydroxyethyl-aminomethyl ) -phenol, and their acid addition salts.

(IV) The ortho-aminophenols which can be used as oxidation bases in the context of the present invention are in particular chosen from 2-amino-phenol, 2-amino-1-hydroxy-5-methyl-benzene, 2-amino-1-hydroxy-6-methyl-benzene, 5-acetamido-2-amino-phenol, and their acid addition salts.

(V) Among the heterocyclic bases which can be used as oxidation bases in the dye compositions in accordance with the invention, mention may more particularly be made of pyridine derivatives, pyrimidine or pyrazolopyrimidine derivatives, pyrazole derivatives, and their addition salts acid.

Among the pyridine derivatives, mention may be made more particularly of the compounds described for example in patents GB 1 026 978 and GB 1 153 196, such as 2,5-diaminopyridine, 2- (4-methoxyphenyl) -amino-3-amino - pyridine, 2,3-diamino-6-methoxypyridine, 2- (β-methoxyethyl) -amino-3-amino-6-methoxy pyridine, 3,4-diamino-pyridine, and their addition salts d 'acid.

Among the pyrimidine derivatives, mention may be made more particularly of the compounds described for example in German patents DE 2,359,399 or Japanese patents JP 88-169 571 and JP 91-10659 or patent applications WO 96/15765, such as 2,4, 5,6-tetra-aminopyrimidine, 4-hydroxy-2,5,6-triaminopyrimidine, 2-hydroxy-4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6-diaminopyrimidine, 2, 5,6-triaminopyrimidine, and pyrazolopyrimidine derivatives such as those mentioned in patent application FR-A-2 750 048 and among which mention may be made of pyrazolo- [1,5-a] -pyrimidine-3,7-diamine; 2,5-dimethylpyrazolo- [1,5-a] -pyrimidine-3,7-diamine; pyrazolo- [1,5-a] -pyrimidine-3,5-diamine; 2,7-dimethyl-pyrazolo- [1,5-a] - pyrimidine-3,5-diamine; 3-amino-pyrazolo- [1,5-a] -pyrimidin-7-ol; 3-amino-pyrazolo- [1,5-a] -pyπmidin-5-ol; 2- (3-amino-pyrazolo- [1,5-a] - pyrimidin-7-ylamino) -ethanol; 2- (7-amino-pyrazolo- [1,5-a] -pyrimidm-3-ylamino) -ethanol; 2 - [(3-amino-pyrazolo [1,5-a] pyrimidin-7-yl) - (2-hydroxyethyl) -amino] -ethanol; 2 - [(7 amino-pyrazolo- [1,5-a] -pyrimidin-3-yl) - (2-hydroxy-ethyl) -amino] -ethanol; 5,6-dimethylpyrazolo- [1,5-a] -pyrimidine-3,7-diamine; 2,6-dimethyl-pyrazolo- [1,5-a] -pyrimidine-3,7-diamine; 2,5, N7, N7-tetramethyl-pyrazolo- [1,5-a] -pyrimidine-3,7-diamine; 3-amino-5-methyl-7-imidazolylpropylamino-pyrazolo- [1,5-a] -pyrimidine; and their acid addition salts and their tautomeric forms, when there is a tautomeric equilibrium.

Among the pyrazole derivatives, mention may more particularly be made of the compounds described in patents DE 3 843 892, DE 4 133 957 and patent applications WO 94/08969, WO 94/08970, FR-A-2 733 749 and DE 195 43 988 such as 4,5-diamino-1-methylpyrazole, 3,4-diamino-pyrazole, 4,5-diamino-l- (4'-chlorobenzyl) -pyrazole, 4,5-diamino-1,3 -dimethyl-pyrazole, 4,5-diammo-3-methyl-1-phenylpyrazole, 4,5-diamino-1-methyl-3-phenyl-pyrazole, 4-amino-1,3-dimethyl-5- hydrazino-pyrazole, l-benzyl-4,5-diamino-3-methyl-pyrazole, 4,5-diamino-3-tert-butyl-l-methyl-pyrazole, 4,5-diamino-l -tert -butyl-3-methyl-pyrazole, 4,5-diamino-l - (β- hydroxy ethyl) -3-methylρyrazole, 4,5-diamino-l- (β-hydroxyethyl) -pyrazole, 4,5 -diamino-1-ethyl-3-methylpyrazole, 4,5-diamino-1-ethyl-3- (4'- methoxyphenyl) -pyrazole, le4,5-diamino-1-ethyl-3-hydroxymethyl-pyrazole, 4,5-diamino-3-hydroxymethyl-1-methyl-pyrazole, 4,5-diamino-3-hydroxymethyl-1-isopropyl-p yrazole, 4,5-diamino-3-methyl-1-isopropylpyrazole, 4-amino-5- (2'-aminoethyl) -amino-1, 3-dimethyl-pyrazole, 3,4,5-triaminopyrazole, l-methyl-3,4,5-triamino-pyrazole, 3,5-diamino-1-methyl-4-methylaminopyrazole, 3,5-diamino-4- (β-hydroxyethyl) amino-l- methyl- pyrazole, and their acid addition salts.

According to the present invention, the oxidation bases preferably represent from 0.0005 to 12% by weight approximately of the total weight of the oxidation dye composition and even more preferably from 0.005 to 8% by weight approximately of this weight. The couplers which can be used in the oxidation dye compositions according to the invention are those conventionally used in the field of oxidation dyes of hair fibers, that is to say meta-aminophenols, meta-phenylenediamines, metadiphenols , naphthols and heterocyclic couplers such as, for example, indole derivatives, indolinic derivatives, sesamol and its derivatives, pyridine derivatives, pyrazolotriazole derivatives, pyrazolones, indazoles, benzimidazoles, benzothiazoles, benzoxazoles, 1 , 3-benzodioxoles, quinolines and their acid addition salts.

These couplers are more particularly chosen from 2,4-diamino l- (β-hy droxy ethyloxy) -benzene, 2-methyl-5-amino-phenol, 5-N- (β- hy droxy ethyl) -amino -2-methyl-phenol, 3-amino-phenol, 1,3-dihydroxy-benzene, 1,3-dihydroxy-2-methyl-benzene, 4-chloro-1,3, di-hydroxy-benzene, 2-amino 4- (β-hydroxyethylamino) -1-methoxy-benzene, 1,3-diamino-benzene, 1,3-bis- (2,4-diaminophenoxy) -propane, sesamol, 1- amino -2-methoxy-4,5-methylenedioxybenzene, α-naphthol, 6-hydroxy-indole, 4-hydroxy-indole, 4-hydroxy-N-methylindole, 6-hydroxy-indoline, 2, 6-dihydroxy-4-methyl-pyridine, 1H-3-methyl-pyrazol-5-one, 1-phenyl-3-methyl-pyrazol-5-one, 2-amino-3-hydroxypyridine, 3, 6- dimethyl-pyrazolo- [3,2-c] -1,4,4-triazole, 2,6-dimethyl-pyrazolo- [1,5b] - 1,2,4-triazole and their addition salts acid.

When present, these couplers preferably represent from 0.0001 to 10% by weight of the total weight of the composition, and even more preferably from 0.005 to 5% by weight.

In general, the acid addition salts of the oxidation bases and couplers are especially chosen from hydrochlorides, hydrobromides, sulphates, tartrates, lactates and acetates.

As indicated above during the description of redox enzymes, 2-electron oxidoreductases need the presence of a specific donor which, preferably, is not encapsulated with the enzyme but added to the medium. cosmetically acceptable. The concentration of the donors specific to two-electron oxidoreductases in the oxidation dye compositions of the present invention is preferably between 0.01 and 20%, and in particular between 0.1 and 5% of the total weight of the composition of oxidation dye.

When the redox enzyme is a peroxidase requiring for its operation a specific donor, the latter is present in the oxidation dye compositions in an amount of 0.001 to 20% by weight, relative to the total weight of the composition .

The mediators capable of activating the 4-electron oxidoreductases described above, when they are present in the dye compositions of the present invention, preferably represent from 0.0001 to 5% by weight, and more preferably from 0.005 at 5% by weight, based on the total weight of the composition.

The compositions may also contain antioxidants. These can be chosen in particular from sodium sulfite, thioglycolic acid, thiolactic acid, sodium bisulfite, dehydroascorbic acid, hydroquinone, 2-methylhydroquinone, tert-butylhydroquinone, 3 -methyl-1-phenyl-5-pyrazolone and homogentisic acid and are generally present in proportions of between approximately 0.05 and 1.5% by weight relative to the total weight of the composition.

The compositions may also contain cosmetic active principles and formulation adjuvants usually used in oxidation dye compositions, such as preserving agents, polymeric thickeners, cationic, anionic, nonionic or zwitterionic surfactants, dyes, fragrances, fillers, vitamins or conditioners.

The compositions can be in various forms, for example in the form of a liquid, a cream or a gel. They can also be pressurized in an aerosol can in the presence of a propellant.

The process for the oxidation dyeing of keratin fibers and in particular the hair of the present invention consists in applying to the keratin fibers an oxidation dye composition described above, leaving the composition in contact with the fibers for a time. sufficient to obtain the desired coloration, for example for a period of between 10 minutes and 1 hour, to remove the dye composition by rinsing and washing, then drying the hair.

In one embodiment of the oxidation dyeing process for keratin fibers of the present invention, the oxidation dyeing compositions are prepared, immediately before application, by introduction of the microcapsules containing the redox enzymes according to the present invention , in a suitable dye composition containing, in a physiologically acceptable support, at least one oxidation dye precursor chosen from oxidation bases and / or couplers.

The following examples illustrate the process for encapsulating redox enzymes and the use of the microcapsules obtained for dyeing the hair.

Example 1

Uricase encapsulation by multiple emulsification-evaporation

An aqueous uricase solution is prepared (enzymatic activity:

20,000 U / g) at 25% by weight and at pH 9. 10 ml of this solution are emulsified for 5 minutes with 50 ml of dichloromethane containing 5% by weight of cellulose acetopropionate (CAP-482-0, 5 Eastman Chemical Company) using a rotor-stator type homogenizer, keeping the temperature below 25 ° C. The primary emulsion obtained is dispersed for 20 minutes in 500 ml of an aqueous solution containing 1% poly (vinyl alcohol) (Airvol ^® 203, Air Products Chemicals Inc.) using a homogenization apparatus rotor-stator or propeller type. During this step, care is also taken not to allow the temperature of the dispersion to exceed a value of 25 ° C.

The dichloromethane is then evaporated using a rotary evaporator (Bϋchi B-480) for 5 hours at 20 ° C, under a pressure of 40 kPa (400 mbar). An aqueous suspension of microcapsules is thus obtained having an average diameter of 12 μm.

To determine the degree of encapsulation, that is to say the ratio of the amount of enzyme found inside the microcapsules to the total amount of enzyme used at the start, the uricase is measured in the external medium. by UV-visible spectrophotometry at a wavelength of 280 nm. The uricase encapsulation rate found is 90%.

To evaluate the capacity of the microcapsules to retain the encapsulated enzyme without releasing it over time, the microcapsules obtained are washed, they are resuspended in distilled water and the dispersion is maintained for 2 hours with vigorous stirring (1400 Rotations per minute). The spectrophotometric assay at 280 nm highlights the absence of enzyme in the suspension medium. Uricase is therefore effectively retained in the microcapsules.

The microcapsules thus prepared can be lyophilized and redispersed in an aqueous medium. The retention properties of the enzyme by the microcapsules are not degraded by lyophilization.

The lyophilized microcapsules have an enzymatic activity, measured by oximetry using a Hansutech oxygen analyzer after dispersion in water, of approximately 2500 ± 500 U / g of microcapsules. 26

The table below shows the evolution over time of the enzymatic activity of an encapsulated uricase according to example 1 stored at 25 ° C. or at 45 ° C. in comparison with an identical quantity of conserved non-encapsulated uricase. under the same conditions.

It can be seen that the encapsulation slows down significantly the decrease in the enzymatic activity of uricase over time. Example 2

Use of microcapsules containing uricase for oxidation dyeing of hair

The two oxidation dye compositions A and B below are prepared, containing respectively 20,000 U of encapsulated uricase according to Example 1 and 20,000 U of unencapsulated uricase.

The coloring is carried out on natural locks containing 90% white hair, with a bath ratio of 5, after being brought into contact with the oxygen in the air. After an exposure time of 30 minutes, rinse, wash and dry the hair. The coloring properties of the compositions are evaluated according to the colorimetric system L * a * b * in which L * corresponds to the intensity of the shade, a * the position of the shade on the red / green axis, and b * to the position of the shade on the blue / yellow axis. The higher the L * value of a shade, the more intense the shade. Gray shades have a * and b * values close to zero.

The dyeing results obtained with compositions A and B are summarized in the table below.

- These results show that, for an equivalent enzymatic activity, the oxidation dye composition according to the present invention (Composition A) gives a shade intensity practically equivalent (ΔL * <1) to that of a dye composition. oxidation containing the unencapsulated redox enzyme.

We also note that the conservation over time of the dyeing power of composition A is better than for composition B.

The coloring process with composition A is carried out under good safety conditions.

Claims

1. Microcapsules with an aqueous core containing at least one redox enzyme chosen from 2-electron oxidoreductases, 4-electron oxidoreductases and peroxidases, and with a polymeric envelope consisting of at least one polymer chosen from polycaprolactone, poly (3-hydroxybutyrate), poly (ethylene adipate), poly (butylene adipate), esters of cellulose and at least one Ci. ₄ carboxylic acid, copolymers of styrene and anhydride maleic, copolymers of styrene and acrylic acid, styrene-ethylene / butylene-styrene block terpolymers, styrene-ethylene / propylene-styrene block terpolymers, and terpolymers of ethylene, vinyl acetate and anhydride maleic.

2. Microcapsules according to claim 1, characterized in that the enzyme is an oxidoreductase with two electrons chosen from pyranose oxidases, glucose oxidases, glycerol oxidases, lactate oxidases, pyruvate oxidases, uricases, choline oydases, sarcosine oxidases, bilirubin oxidases and amino acid oxidases.

3. Microcapsules according to claim 2, characterized in that the two-electron redoxase is an uricase of animal, microbiological or biotechnological origin.

4. Microcapsules according to claim 2 or 3, characterized in that they have an enzymatic activity of oxidoreductase with 2 electrons between 500 and 10,000 U / g of microcapsules, preferably between 1000 and

5000 U / g of microcapsules.

5. Microcapsules according to claim 1, characterized in that the enzyme is a 4-electron oxidoreductase chosen from laccases, tyrosinases, catechol oxidases and polyphenol oxidases.

6. Microcapsules according to claim 1, characterized in that the enzyme is a peroxidase chosen from peroxidases simplex and catalases.

7. Microcapsules according to claim 1, characterized in that the enzyme is a peroxidase chosen from NADH peroxidases, fatty acids peroxidases, NADPH peroxidases, cytochrome C peroxidases, iodides peroxidases, chlorides peroxidases, L- ascorbates peroxidases and glutathione peroxidases.

8. Microcapsules according to any one of the preceding claims, characterized in that the said envelope consists of cellulose acetopropionate.

9. Microcapsules according to any one of the preceding claims, characterized in that they contain from 1 to 30% by weight, and in particular from 2 to 20% by weight of redox enzyme, based on the weight total microcapsules

10. Microcapsules according to any one of the preceding claims, characterized in that the aqueous core additionally contains one or more low molecular weight polyols and / or one or more water-soluble polymers.

11. Microcapsules according to any one of the preceding claims, characterized in that the weight ratio of the encapsulated internal aqueous phase forming the core of the microcapsules to the wall of these is between 0.1 / 1 and 50 / 1 preferably between 0.5 / 1 and 10/1.

12. Microcapsules according to any one of the preceding claims, characterized in that they have an average diameter of between 0.5 μm and 500 μm, preferably between 1 μm and 100 μm.

13. anhydrous microcapsules obtained by dehydration of the microcapsules according to any one of the preceding claims.

14. Anhydrous microcapsules according to claim 13, characterized in that they contain from 2 to 95%, preferably from 5 to 70% by weight of redox enzyme.

15. A method of manufacturing microcapsules according to any one of claims 1 to 14, comprising the following successive steps (a) solubilization or dispersion in an aqueous phase of at least one redox enzyme,

(b) emulsification of the aqueous solution or dispersion obtained in step (a) in a solution of at least one polymer chosen from polycaprolactone, poly (3-hydroxybutyrate), poly (ethylene adipate), the esters of cellulose and at least one carboxylic acid Ci. _4, poly (butylene adipate), copolymers of styrene and maleic anhydride, copolymers of styrene and acrylic acid, styrene terpolymers sequences ethylene / butylene styrene, the styrene-ethylene / propylene-styrene block terpolymers, and the terpolymers of ethylene, vinyl acetate and maleic anhydride, in a water-immiscible organic solvent,

(e) partial or total elimination of water, characterized in that the redox enzyme is chosen from 2-electron redoxases, 4-redox reductases and peroxidases.

16. The method of claim 15, characterized in that the organic solvent immiscible with water used in step (b) is chosen from dichloromethane, cyclohexane, heptane, 1-chloro-butane and ethyl acetate.

17. The method of claim 15 or 16, characterized in that said stabilizing agent of the emulsion used in step (c) is chosen from ρoly (vinyl alcohol), polyvinylpyrrolidone, water-soluble styrene-maleic anhydride copolymers , carboxymethylcellulose, starch, chitosan and polyacrylic acid.

18. Composition for the oxidation dyeing of keratin fibers such as the hair, containing, in a physiologically acceptable medium, at least one oxidation dye precursor chosen from oxidation bases and / or couplers, characterized by the fact that it contains microcapsules with an aqueous core and a polymeric envelope according to any one of claims 1 to 14.

19. An oxidation dye composition according to claim 18, characterized in that said microcapsules represent from 0.01% to 50%, preferably from 0.1 to 30% of the total weight of the oxidation dye composition. .

20. An oxidation dye composition according to claim 18 or

19, characterized in that the oxidation bases are chosen from ortho- and para-phenylenediamines, double bases, ortho- and para-aminophenols and heterocyclic bases, as well as their acid addition salts.

21. An oxidation dye composition according to claim 20, characterized in that the paraphenylenediamines are chosen from those of formula (I) and their acid addition salts:

in which:

Ri represents a hydrogen atom, an alkyl radical Cι-C ₄ monohydroxyalkyl, C ₁ -C ₄ polyhydroxyalkyl, C ₂ -C ₄ alkoxy _(Cι-C4) - alkyl ^• (Cι-C _4), C ₁ -C ₄ alkyl substituted by a nitrogen, phenyl or 4'-aminoρhenyl group;

R ₂ represents a hydrogen atom, a C ₁ -C ₄ alkyl, CC ₄ monohydroxyalkyl or C ₂ -C ₄ polyhydroxyalkyl, alkoxy (C _r C ₄ ) (Cι-C ₄ ) alkyl or C alkyl radical ₁ -C ₄ substituted with a nitrogen group; or

R ₃ represents a hydrogen atom, a halogen atom such as a chlorine atom, an alkyl radical in C ₁ -C ₄ alkyl, sulfo, carboxy, monohydroxyalkyl, C ₁ -C ₄ alkyl or hy droxy alkoxy C ₁ -C ₄ acetylaminoalkoxy, C ₁ -C ₄ mesylaminoalkoxy or C ₁ -C ₄ carbamoylaminoalkoxy C ₁ -C _4,

R ₄ represents a hydrogen or halogen atom or a G _r C ₄ alkyl radical.

22. An oxidation dye composition according to claim 21, characterized in that the paraphenylenediamines are chosen from paraphenylenediamine, paratoluylenediamine, 2-chloroparaphenylenediamine, 2,3-dimethyl-paraphenylenediamine, 2,6-dimethylparaphenylenediamine, 2,6-diethyl-paraphenylenediamine, 2,5-dimethylparaphenylenediamine, N, N-dimethyl-paraphenylenediamine, N, N-diethylparaphenylenediamine, N, N-dipropyl-paraphenylenediamine,

4-amino-NN-diethy 1-3 -methyl 1-aniline, N, N-bis- (β-hydroxyethyl) - paraphenylenediamine, 4-N, N-bis- (β-hydroxyethyl) amino-2-methyl -aniline, 4-N, N-bis- (β-hydroxyethyl) -amino-2-chloro-aniline, 2-β-hydroxyethyl- paraphenylenediamine, 2-fluoro-paraphenylenediamine, 2-isopropyl- paraphenylenediamine, N- (β-hydroxypropyl) -paraphenylenediamine, 2- hy droxy methyl 1-parapheny lenediamine, N, N-dimethyl 1-3 -methyl lpara- phenylenediamine, N, N- (ethyl-β-hydroxyethyl) -paraphenylenediamine , N- (β, γ-dihydroxypropyl) -paraphenylenediamine, N- (4'-aminophenyl) - paraphenylenediamine, N-phenyl-paraphenylenediamine, 2-β- hydroxyethyloxy-paraphenylenediamine, 2-β-acetylaminoethyloxy- paraphenylenediamine, N- (β-methoxyethyl) ρaraρhenylenediamine, 2-methyl-1-N-β-hydroxyethyl-paraphenylenediamine, and their acid addition salts.

23. An oxidation dye composition according to claim 20, characterized in that the double bases are chosen from the compounds corresponding to the following formula (II), and their acid addition salts:

in which

- Z] and Z ₂ , identical or different, represent a hydroxyl radical or - NH ₂ optionally substituted by a C ₁ -C ₄ alkyl radical or by a connecting arm Y;

- R ₅ and R _e independently represent a hydrogen or halogen atom, an alkyl radical Cι-C ₄ monohydroxyalkyl, C ₁ -C ₄ polyhydroxyalkyl, C ₂ -C ₄ aminoalkyl or Cι-C ₄ a link arm Y;

- R ₇ , R ₈ , R ₉ , Rio, Rn and R ₁₂ , identical or different, represent a hydrogen atom, a linker Y or a C ₁ -C ₄ alkyl radical; it being understood that the compounds of formula (II) have only one linker arm Y per molecule.

24. An oxidation dye composition according to claim 23, characterized in that the double bases are chosen from N, N'-bis- (β-hydroxyethyl) -N, N'-bis- (4'-aminophenyl ) -l, 3-diamino-propanol, N, N'- bis- (β-hydroxyethyl) -N, N'-bis- (4'-amino-phenyl) -ethylenediamine, N, N'- bis- (4-aminophenyl) -tetramethylenediamine, N, N'-bis- (β-hydroxyethyl) - N, N'-bis- (4-aminophenyl) -tetramethylene diamine, N, N'-bis- (4- methylaminophenyl) -tetramethylenediamine, N, N'-bis- (ethyl) -N, N'-bis- (4'-amino- 3'-methylphenyl) -ethylenediamine, 1, 8-bis- (2, 5-diaminophenoxy) -3,5- dioxaoctane, and their acid addition salts.

25. An oxidation dye composition according to claim 20, characterized in that the para-aminophenols are chosen from those corresponding to the following formula (III), and their addition salts with an acid:

in which

Rι ₃ represents a hydrogen atom, a halogen atom such as fluorine, an alkyl radical in C _r C ₄ , monohydroxyalkyl in C ₁ -C ₄ , alkoxy (Cι- C) alkyl (Cι-C ₄ ) or amino C ₁ -C ₄ alkyl, or hy droxy alkyl (C ₁ -C) amino C ₁ -C ₄ alkyl.

R ₁₄ represents a hydrogen atom or a halogen atom such as fluorine, an alkyl radical in C ₁ -C ₄ monohydroxyalkyl, C ₁ -C ₄ polyhydroxyalkyl, C ₂ -C ₄ aminoalkyl, C ₁ - C ₄ , C ₁ -C ₄ cyanoalkyl or alkoxy (Cι-C ₄ ) -alkyl (Cι-C ₄ ).

26. An oxidation dye composition according to claim 25, characterized in that the para-aminophenols are chosen from para-aminophenol, 4-amino-3-methyl 1-phenol, 4-amino-3-fluoro -phenol, 4-amino-3-hydroxymethyl-phenol, 4-amino-2-methyl-phenol, 4-amino-2- hydroxymethyl-phenol, 4-amino-2-methoxymethyl-phenol, 4-amino-2-aminomethyl-phenol, 4-amino-2- (β-hydroxyethyl-aminomethyl) -phenol, and their addition salts d 'acid.

27. An oxidation dye composition according to claim 20, characterized in that the ortho-aminophenols are chosen from 2- amino-phenol, 2-amino-1-hydroxy-5-methyl-benzene, 2- amino-1-hydroxy-6-methyl-benzene, 5-acetamido-2-amino-phenol, and their acid addition salts.

28. An oxidation dye composition according to claim 20, characterized in that the heterocyclic bases are chosen from pyridine derivatives, pyrimidine or pyrazolopyrimidine derivatives, pyrazole derivatives, and their acid addition salts.

29. An oxidation dye composition according to claim 28, characterized in that the pyridine derivatives are chosen from 2,5-diaminopyridine, 2- (4-methoxyρhenyl) -amino-3-amino-pyridine, 2 , 3-diamino-6-methoxypyridine, 2- (β-methoxyethyl) -amino-3-amino-6-methoxy pyridine, 3,4-diamino-pyridine, and their acid addition salts.

30. An oxidation dye composition according to claim 28, characterized in that the pyrimidine or pyrazolopyrimidine derivatives are chosen from 2,4,5,6-tetra-aminopyrimidine, 4-hydroxy-2,5,6- triaminopyrimidine, 2-hydroxy-4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6-diaminopyrimidine, 2,5,6-triaminopyrimidine, pyrazolo- [1,5-a] -pyrimidine- 3,7-diamine; 2,5-dimethylpyrazolo- [1,5-a] - pyrimidine-3,7-diamine; pyrazolo- [1,5-a] -pyrimidine-3,5-diamme; 2,7-dimethyl-pyrazolo- [1,5-a] -pyrimidine-3,5-diamine; 3-amino-pyrazolo- [1,5-a] -pyrimidin-7-ol; 3-amino-pyrazolo- [1,5-a] -pyrimidin-5-ol; 2- (3-amino-pyrazolo- [1,5-a] -pyrimidin-7-ylamino) -ethanol; 2- (7-amino-pyrazolo- [1,5-a] -pyrimidin-3-ylamino) -ethanol; 2 - [(3-amino-pyrazolo [1,5-a] pyrimidin-7-yl) - (2-hydroxy-ethyl) -amino] -ethanol; 2 - [(7 amino-pyrazolo- [1,5-a] -pyrimidin-3-yl) - (2-hydroxy-ethyl) -amino] -ethanol; the 5,6- dimethylpyrazolo- [1,5-a] -pyrimidine-3,7-diamine; 2,6-dimethyl-pyrazolo- [1,5-a] -pyrimidine-3,7-diamine; 2,5, N7, N7-tetramethyl-pyrazolo- [1,5-a] - pyrimidine-3,7-diamine; 3-amino-5-methyl-7-imidazolylpropylamino-pyrazolo- [1,5-a] -pyrimidine; and their acid addition salts and their tautomeric forms, when there is a tautomeric equilibrium.

31. An oxidation dye composition according to claim 28, characterized in that the pyrazole derivatives are chosen from 4,5-diamino-1-methyl-pyrazole, 3,4-diamino-pyrazole, 4,5- diamino-1- (4'- chlorobenzyl) -pyrazole, 4,5-diamino-1,3-dimethyl-pyrazole, 4,5-diamino-

3 -methy 1-1-pheny lpyrazole, 4,5-diamino-1-methyl-3-phenyl-pyrazole, 4-amino-1,3-dimethyl-5-hydrazino-pyrazole, l-benzyl-4 , 5-diamino-3-methyl-pyrazole, 4,5-diamino-3-tert-butyl-1-methyl-pyrazole, 4,5-diamino-1-tert-butyl-3-methyl-pyrazole, 4,5-diamino-l- (β-hydroxyethyl) -3-methyl-pyrazole, 4,5-diamino-l- (β-hydroxyethyl) -pyrazole, 4,5-diamino-l-ethyl-

3-methyl-pyrazole, 4,5-diamino-1-ethyl-3- (4'-methoxyphenyl) -pyrazole, 4,5-diamino-1-ethyl-3-hydroxymethyl-pyrazole, 4,5-diamino- 3- hy droxy méthy 1-1 -méthy 1-pyrazole, 4,5-diamino-3-hydroxymethyl-l- isopropyl-pyrazole, 4,5-diamino-3-methyl-l-isopropylpyrazole, 4-amino - 5- (2'-aminoethyl) -amino-1,3-dimethyl-pyrazole, 3,4,5-triaminopyrazole, l-methyl-3, 4,5-triamino-pyrazole, 3,5-diamino -1-methyl-4-methylaminopyrazole, 3,5-diamino-4- (β-hydroxyethyl) amino-1-methyl-pyrazole, and their acid addition salts.

32. An oxidation dye composition according to any one of claims 18 to 31, characterized in that the oxidation base (s) represent from 0.0005 to 12%, preferably from 0.005 to 8%, of the total weight of the composition.

33. An oxidation dye composition according to any one of claims 18 to 32, characterized in that the coupler (s) are chosen from meta-aminophenols, meta-phenylenediamines, metadiphenols, naphthols and heterocyclic couplers such as for example the indole derivatives, the indoline derivatives, sesamol and its derivatives, pyridine derivatives, pyrazolotriazole derivatives, pyrazolones, indazoles, benzimidazoles, benzothiazoles, benzoxazoles, 1,3-benzodioxoles, quinolines and their acid addition salts.

34. An oxidation dye composition according to claim 33, characterized in that the coupler (s) are chosen from 2,4-diamino l- (β-hy droxy ethyloxy) -benzene, 2-methyl-5- amino-phenol, 5-N- (β- hydroxyethyl) -amino-2-methyl-phenol, 3-amino-phenol, 1,3-dihydroxy-benzene, l, 3-dihydroxy-2-méfhyl- benzene, 4-chloro-1,3-dihy droxy -benzene, 2-amino 4- (β-hydroxyethylamino) -l-methoxy-benzene, 1,3-diamino-benzene, 1,3-bis- (2,4-diaminophenoxy) -propane, sesamol, 1-amino-2-methoxy-4,5-methylenedioxybenzene, -naphthol, 6-hydroxy-indole, 4-hydroxy-indole, 4- hydroxy-N-methylindole, 6-hydroxyindoline, 2,6-dihydroxy-4-methyl-pyridine, 1H-3-methyl-pyrazol-5-one, 1-phenyl-3-methyl-pyrazol- 5-one, 2-amino-3-hydroxypyridine, 3,6-dimethyl-pyrazolo- [3,2-c] -1,2,4-triazole, 2,6-dimethyl-pyrazolo- [1, 5b] - 1,2,4-triazole and their acid addition salts.

35. An oxidation dye composition according to any one of claims 18 to 34, characterized in that the coupler (s) represent from 0.0001% to 10%, preferably from 0.005 to 5% of the total weight of the composition.

36. An oxidation dye composition according to any one of claims 18 to 36, characterized in that, when the encapsulated redox enzyme is a 2-electron oxidoreductase, the composition contains from 0.01 to 20% by weight, preferably from 0.1 to 5% by weight relative to the total weight of the oxidation dye composition, of a donor for said 2-electron oxidoreductase.

37. An oxidation dye composition according to any one of claims 18 to 35, characterized in that, when the encapsulated redox enzyme is a peroxidase requiring for its operation a specific donor, the latter is present in an amount of 0.001 to 20% by weight, relative to the total weight of the composition.

38. An oxidation dye composition according to any one of claims 18 to 35, characterized in that, when the encapsulated redox enzyme is a 4-electron oxidoreductase, the composition contains from 0.0001 to 5% by weight, preferably from 0.005 to 5% by weight, relative to the total weight of the composition, of one or more mediators capable of activating said 4-electron oxidoreductase.

39. Multicomponent oxidation dyeing kit comprising at least a first component containing microcapsules with an aqueous core and a polymeric envelope according to any one of claims 1 to 14, and at least a second component containing at least one dye precursor d oxidation chosen from oxidation bases and / or couplers, the two components being kept separately and intended to be mixed with each other immediately before application to the keratin fibers.

40. Process for the oxidation dyeing of keratin fibers and in particular the hair, consisting in applying to the fibers an oxidation dye composition according to any one of claims 18 to 38, or an oxidation dye composition prepared, immediately before application, by mixing the two components of the oxidation dye kit according to claim 39, leaving the composition in the presence of air in contact with the fibers for a time sufficient to obtain the desired coloration, eliminating the composition dye by rinsing and washing, then drying the hair.