NO production and uses thereof

FIELD OF THE INVENTION The invention relates to a cosmetic or pharmaceutical composition containing the combination of 2, 4-diaminopyrimidine 3-N-oxide and of an agent for promoting the NO production, for inducing and/or stimulating the growth of human keratin fibres, and in particular of the hair and the eyelashes, and/or for stopping the loss thereof. It also relates to a cosmetic treatment process for stimulating the growth of these human keratin fibres and/or for stopping the loss thereof, and also to the use of the combination of 2, 4-diaminopyrimidine 3-N-oxide and of an agent for promoting the NO production, for inducing and/or stimulating hair or eyelash growth and/or for stopping loss thereof.

The human keratin fibres to which the invention applies are in particular head hair, the eyebrows, the eyelashes, beard hairs, moustache hairs and pubic hair. More especially, the invention applies to human head hair and/or eyelashes.

Thus, more specifically, the invention relates to a physiologically acceptable composition which contains 2, 4-diaminopyrimidine 3-N-oxide and an agent for promoting the NO production for improving the condition of human hair, and in particular inducing

agent for promoting the NO production for improving the condition of human hair, and in particular inducing and/or stimulating hair growth and/or stopping hair loss. 2, 4-diaminopyrimidine 3-N-oxide is known under the name aminexil or 2,4-DPO.

Thus, the present invention relates more particularly to a physiologically acceptable and in particular cosmetic composition containing the combination of ^NO-releasing" compounds in particular amino acids and more particulary arginine and its derivatives (polyarginine) , and/or of arginase inhibitors, with aminexil, this composition being intended to induce and/or stimulate hair growth and/or stop hair loss.

BACKGROUND OF THE INVENTION Hair growth and hair renewal are mainly determined by the activity of the hair follicles and of their matrix environment. Their activity is cyclical and comprises essentially three phases, namely the anagenic phase, the catagenic phase and the telogenic phase.

The anagenic phase (active phase or growth phase) , which lasts several years and during which the hair gets longer, is followed by a very short and transient catagenic phase which lasts a few weeks . During this phase, the hair undergoes a change, the

follicle becomes atrophied and its dermal implantation appears higher and higher .

The terminal phase or telogenic phase, which lasts a few months, corresponds to a resting phase of the follicle and the hair ends up by falling out. At the end of this resting period, a new follicle is generated in situ, and another cycle begins.

The head of hair is thus under permanent renewal and, out of the approximately 150 000 hairs that make up a head of hair, approximately 10% are at rest and will be replaced within a few months.

Hair growth and hair renewal are mainly determined by the activity of the hair follicles and of their matrix environment. The head of hair is therefore undergoing permanent renewal, but by adulthood, the vascular system of the skin is fully developed and does not undergo any further modification except in the hair follicles, where it undergoes considerable variations at each hair cycle . Furthermore, although the exact mechanism of alopecia has not been explained, recent research has demonstrated the involvement of an autoimmunity imbalance. Several observations suggest the involvement of Thl-type cytokines in the appearance of alopecia. A Th2-type profile could promote the repair of tissues damaged by Thl-type lymphocytes .

Thus, NO (nitric oxide) , at non-cytotoxic

concentrations is known to promote the Th2 pathway to the detriment of the ThI pathway.

Moreover, disturbances in the microcirculation and neurotransmitter impairment have been observed in skin affected by alopecia. In particular, decreases in CGRP (calcitonin gene-related peptide) have been observed in alopecia-affected follicles and in the serum of patients exhibiting complete alopecia. CGRP is a powerful cutaneous vasodilator. Low concentrations of CGRP could stimulate an immune reaction and reduce vasodilation in the skin, thus probably resulting in a decrease or in an absence of hair growth.

NO, by virtue of its stimulatory effects on CGRP production, could stimulate vasodilation in the skin and promote the immunostimulatory action of CGRP (M.R. Namazi, Inflamm. Res., 52, 2003).

In adulthood, the vascular system of the skin is fully developed and does not undergo any further modification, except in the hair follicles, where it undergoes considerable variations at each hair cycle. The hair follicle is in fact a richly innervated and highly vascularized cutaneous structure. In general, the phenomenon of development of the microcirculation is called angiogenesis . At the beginning of each anagenic phase, it is necessary to develop strong activation of angiogenesis in order to re-develop the

perifollicular vascular micro-network. The involution of this network and the disappearance of the capillaries of the dermal papilla go together with the change in phase and the passing into the catagenic phase. At this stage, the blood microcapillaries collapse and disappear.

In parallel, in the alopecia-affected areas, perifollicular fibrosis sets in, the follicles become smaller cycle after cycle, and, gradually, the vascularization of the bulbs becomes less and less.

The angiogenesis phenomenon observed during the anagenic phase depends on many trophic factors, on cytokines or on other biologically active molecules provided by the bloodstream or which are produced locally in particular by the fibroblasts of the dermal papilla or the bulbar keratinocytes . Among these trophic factors, mention may be made of endothelial cell growth factor (also called vascular endothelial growth factor (VEGF) ) . This factor is essential for angiogenesis and increases vascular permeability.

Studies have shown that the expression of this factor is increased during the anagenic phase of the hair cycle. Thus, this factor contributes to maintaining a functional microvascularization around the hair follicle, and in particular around the base of the bulb and the dermal papilla, and also to providing nutrients necessary for correct hair growth.

The perifollicular microcirculation therefore plays an essential role in the hair growth process by providing the factors and the nutrients necessary for the growth of this follicle. Due to the essential role of the perifollicular microcirculation, any deficiency in the latter results in a decrease in the provision of the nutrient and gaseous (in particular oxygen) elements necessary for hair growth, leading to hair growth disorders and the gradual setting in of alopecia.

The natural loss or falling-out of the hair may be estimated, on average, as being a few hundred hairs per day for a normal physiological state. This process of permanent physical renewal undergoes a natural change during ageing, the hairs become finer and their cycles shorter.

Moreover, in certain inflammatory scalp dermatoses, such as for example psoriasis or seborrhoeic dermatitis, hair loss may be greatly increased and the renewal cycles of the follicles may be greatly disturbed.

Furthermore, various causes may result in a substantial, temporary or permanent loss of hair. This may be loss and impairment of hair after pregnancy, during states of dietary malnutrition or imbalance, during physiological stress, or during states of asthenia or of hormonal dysfunction, as may be the case

during or after the menopause. It may also be a case of loss or impairment of the hair related to seasonal phenomena .

It may also be a matter of alopecia, which is essentially due to a disturbance in hair renewal, resulting, in a first stage, in acceleration of the frequency of the cycles to the detriment of the quality of the hair, and then of their quantity. A gradual depletion of the head of hair then occurs and the hairs become gradually smaller, together with isolation of the bulbs due to a gradually increasing thickness of the perifollicular collagen matrix and of the outer connective sheath. Revascularization is therefore made more difficult cycle after cycle. The successive growth cycles result in hairs that become finer and shorter, gradually transforming into an unpigmented down. Certain areas are preferentially affected, especially the temporal or frontal lobes in men, and a diffuse alopecia of the crown of the head in women. The term "alopecia" also covers an entire family of afflictions of the hair follicle whose final consequence is the permanent, partial or general loss of the hair. It is more particularly a matter of androgenic alopecia. In a large number of cases, early loss of hair occurs in genetically predisposed individuals; this is then androchronogenetic alopecia; this form of alopecia especially affects men.

In general, any factor that results in an increase in blood supply to the hair follicle, either by activating angiogenesis or by opposing the regression thereof, or by acting on the rnicrovessels so as to limit their constriction, will have a beneficial effect on the energy supply required for correct growth of this same follicle.

In the cosmetics or pharmaceutical industry, compositions that make it possible to eliminate or reduce alopecia, and in particular to induce or stimulate hair growth or to decrease hair loss, have been sought for many years . One of the pathways explored is precisely the maintenance of the vascularization around the hair follicle. As a known molecule that acts specifically on the formation and the taking hold of perifollicular fibrosis, mention may be made of aminexil (WO 96/09048 from L'Oreal) , which has an inhibitory activity on the expression of lysyl hydroxylase. Lysyl hydroxylase and prolyl hydroxylase are enzymes involved in the formation of collagen fibres, and the deregulation of the functions thereof is one of the factors responsible for the development of perifollicular fibrosis. Aminexil corresponds to the formula below:

Aminexil (2,4-DPO)

In addition, other documents exist that describe the use of NO-releasing agents, for topical application, intended to stimulate hair growth by acting on the microcirculation of the scalp. Thus, the patent document by Proctor (EP 327 263) describes the use of NO radical-producing compounds in combination with reducing agents, antioxidants and with hydroxyl radical scavengers . Another patent document by E. Fossel (WO 99/13717) describes the use of arginine and of its derivatives, as an NO-synthase substrate, for the in vivo formation of NO and their use (inter alia) in the treatment of alopecia. Another patent document by Shiseido (JP 07316023) also describes the use of arginine and of its derivatives in the treatment of alopecia. Finally, document WO 03/072039 by Essentia Biosystems describes the use of an arginine oligomer containing from 7 to 15 arginine units, for the treatment of hair loss.

Document EP 1 393 732 by Taisho Pharmaceutical describes, moreover, the use of minoxidil or 2, 4-diamino-6-piperidinopyrimidine 3-oxide and of arginine in the treatment of hair loss, the arginine making it possible to reduce the minoxidil coloration over time, the latter being known and used as an active agent for the treatment of hair loss (see US 4 139 619 and US 4 596 812 by Upjohn Company); minoxidil is a potassium channel agonist compound.

Although the compounds known and used for treating alopecia all exhibit advantages, cosmeticians are always seeking novel products to satisfy the consumer in search of effective products with a rapid and long-lasting action, two properties that are often antinomic in the field of treatment for alopecia, in particular androgenetic alopecia.

Thus, there remains the need for a novel physiologically acceptable composition for promoting the growth of human hair and/or reducing the loss thereof, which has a rapid and long-lasting action and is easy to use.

DISCLOSURE OF THE INVENTION The inventors have developed a novel physiologically acceptable composition containing the combination of aminexil with one or more agents for promoting the NO production.

This composition allows revascularization of the hair follicle, of its peripheral region and/or of the hair after each growth cycle, and also inhibition of the formation and of the taking hold of perifollicular fibrosis, a factor that worsens poor vascularization of the hair. It thus has a beneficial effect on the scalp, and in particular on hair growth, but also on certain hairs such as the eyelashes or the eyebrows and also on the nails.

The present invention thus relates to a

composition for caring for and/or for treating keratin fibres, in particular human keratin fibres, such as the hair, and also for caring for and/or for treating the skin from which these fibres emerge, containing, in a physiologically acceptable medium, the combination of aminexil with at least one agent for promoting the NO production.

This composition is in particular intended to induce and/or stimulate the growth of keratin fibres and/or to stop the loss thereof and/or to increase the density thereof. The expression "increase the density of keratin fibres, and in particular the hair density," is intended to mean increasing the number of keratin fibres, in particular of hairs, per cm ² of skin such as the scalp.

The invention also relates to the use of the combination of aminexil with at least one agent for promoting the NO production, as an agent for inducing and/or stimulating the growth of keratin fibres of human beings and/or for stopping the loss thereof and/or for increasing the density thereof.

The invention also relates to the cosmetic use of the combination of aminexil with at least one v agent for promoting the NO production, in a cosmetic composition for caring for and/or for making up keratin fibres of human beings, (as an agent) for reducing the loss of keratin fibres and/or for increasing the

density thereof. A subject of the invention is also the use of this combination, for preparing a composition for caring for and/or for treating keratin fibres of human beings, intended to induce and/or stimulate the growth of keratin fibres and/or to stop the loss thereof and/or to increase the density thereof. The human keratin fibres to which the invention applies are in particular head hair, the eyebrows, the eyelashes, beard hairs, moustache hairs, pubic hairs and also the nails. More especially, the invention applies to human head hair and/or human eyelashes .

Thus, a subject of the invention is also the cosmetic use of the combination of aminexil with at least one agent for promoting the NO production, in a cosmetic hair care composition for human beings, as an agent for treating alopecia of natural origin, and in particular androgenic or androchronogenetic alopecia, and also the use of this combination for preparing a hair composition for human beings, intended to treat alopecia of natural origin, and in particular androgenic or androchronogenetic alopecia. Thus, this composition makes it possible to maintain the head of hair in good condition and/or to combat natural hair loss, in particular in men.

A subject of the invention is also the cosmetic use of the combination of aminexil with at

least one agent for promoting the NO production, in a cosmetic composition for caring for and/or for making up the eyelashes of human beings, for inducing and/or stimulating eyelash growth and/or for increasing the density thereof. This composition thus makes it possible to maintain the eyelashes in good condition and/or to improve their condition and/or their appearance. A subject of the invention is also the use of the combination of aminexil with at least one agent for promoting the NO production, for preparing a composition for caring for and/or for treating the eyelashes of human beings, intended to induce and/or stimulate eyelash growth and/or to increase the density thereof . A subject of the invention is also the use of the combination of aminexil with at least one agent for promoting the NO production, for the manufacture of a composition for use in the treatment of disorders related to a reduction in the microcirculation or vascularization of the skin, and in particular of a hair follicle in human beings.

A subject of the present invention is also a cosmetic process for treating human keratin fibres and/or the skin from which these fibres emerge, such as the scalp, intended in particular to stimulate the growth of human keratin fibres such as the hair and the eyelashes of human beings, and/or to stop the loss

thereof, characterized in that it consists in applying, to the human keratin fibres and/or the skin from which these fibres emerge, a cosmetic composition comprising the combination of aminexil with at least one agent for promoting the NO production, in leaving said composition in contact with these keratin fibres and/or said skin, and optionally in rinsing these keratin fibres and/or said skin.

This treatment process has the characteristics of a cosmetic process insofar as it makes it possible to improve the aesthetics of the keratin fibres, and in particular of the hair and of the eyelashes, by giving them greater vigour and an improved appearance. Furthermore, it may be used daily for several months, without a medical prescription.

More especially, a subject of the present invention is a cosmetic process for caring for human hair and/or the human scalp, with a view to improving their condition and/or their appearance, characterized in that it consists in applying, to the hair and/or the scalp, a cosmetic composition according to the invention comprising the combination of aminexil with at least one agent for promoting the NO production, in leaving said composition in contact with the hair and/or the scalp, and optionally in rinsing the hair and/or the scalp .

This process thus allows care of the human

scalp and of human hair, and in particular an anti-hair loss/hair regrowth action, but also an antimicrobial action and, ultimately, an anti-dandruff action, an action promoting healing of the scalp, and an action against human hair becoming greasy.

Thus, a subject of the invention is also the cosmetic use of the combination of aminexil with at least one agent for promoting the NO production, in a cosmetic hair composition, as a scalp care agent, and in particular as an agent with an anti-dandruff action on the scalp, and/or a healing action on the scalp and/or an action against human hair becoming greasy. A subject of the invention is also the use of the combination of aminexil with at least one agent for promoting the NO production, for manufacturing a composition intended to treat and/or limit the formation of dandruff on the scalp and/or to heal the scalp and/or to treat and/or to limit the formation of grease on human hair. A subject of the invention is also a cosmetic process for caring for and/or for making up human eyelashes, with a view to improving their condition and/or their appearance, characterized in that it consists in applying, to the eyelashes, a mascara composition comprising the combination of aminexil with at least one v agent for promoting the NO production and in leaving said composition in contact with the

eyelashes. This mascara composition can be applied alone or as an undercoat for a conventional pigmented mascara, and can be removed like a conventional pigmented mascara, with a conventional makeup-removing cream or lotion.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE

INVENTION

According to the invention, the term "at least one" signifies one or more (2, 3 or more) . In particular, the composition may contain one or more vasodilators or one or more natural amino acids or one or more arginase inhibitors or a mixture of these compounds . Essential features of the invention

Aminexil

The composition according to the invention contains 2, 4-diaminopyrimidine 3-N-oxide. This compound is soluble in water and in a water/alcohol mixture in any proportion. It may be chosen in sufficient amount to obtain, in combination with one or more complementary compounds active on the regrowth of keratin fibres, in particular human keratin fibres, and/or on stopping the loss thereof, an increase in the density of keratin fibres, in particular human keratin fibres, and/or a reduction in the loss thereof, and in particular an increase in the density of human hair

and/or a reduction in the loss thereof. To give an order of magnitude, according to the invention, aminexil can be used, for topical application to the human scalp and human hair, in an amount representing from 10 ^~3 % to 5% of the total weight of the composition, and preferably in an amount representing from 10 ^~2 % to 2% of the total weight of the composition, for example from 0.5% to 2%.

The composition according to the invention also contains one or more complementary compounds active on the regrowth of keratin fibres and/or on stopping the loss thereof, chosen from vasodilators, natural amino acids and arginase inhibitors, and mixtures thereof. Furthermore, some of these complementary compounds may be both vasodilator compounds and natural amino acids. Preferably, the active complementary compound is both a vasodilator compound and an amino acid.

The agents for promoting the NO production are preferably chosen from:

- nitric oxide itself

- nitric oxide (NO) -releasing agents,

- NOS (Nitric Oxide Synthase) synthesis and/or activity stimulators, - mixtures thereof.

NOS (Nitric Oxide Synthase) synthesis and/or activity stimulators

The agents that modulate NO synthesis can act directly on the chemical release of NO, or on the enzymatic release of NO by means of the enzyme for NO synthesis, NO-Synthase or NOS (its various isoforms) .

They may also be elements that ultimately regulate the NO concentration at the cellular level, by acting on the mechanisms of protein synthesis for the enzyme, on the stability and/or the activity of the enzyme and also on the stimulation of its synthesis, on the stability of the NOS mRNA, and/or on the stability of the released NO. Reference is especially made, in the description, to "NOS synthesis and/or activity stimulating agents".

Finally, some interactions at the level of NO metabolism, upstream of its synthesis, can interfere with the final concentration of released NO, by acting on the other enzymes having the same substrate, on the availability of the substrate at the intracellular level, and/or on its transport within the cell.

The term "NO-synthase" covers a family of enzymes that provide the enzymatic catalysis of

L-arginine to citrulline, during which catalysis a multifunctional gaseous mediator, nitric oxide or NO is

produced .

NO-synthases exist in three forms, two constitutive forms, which nomenclature includes neuronal NO-synthase (or NOS 1) and endothelial NO-synthase (or NOS 3) , and the inducible form (or NOS 2) (Medecine/Sciences, 1992, 8, pp. 843-845) .

The NOS activity stimulators agents for promoting can also acton the disponibility of a NO precursor and, in particular in the case of L-arginine, they can be selected from arginase inhibitors. Inhibiting the arginases allows to increase the disponibiity of arginine and to increase the synthesis of NO.

NOS synthesis stimulators

As examples of "NOS synthesis and/or activity stimulators" mention may, for example, be made of arachidonic acid, bradykinin, L-glutamic acid, histamine, hydroxyguanidine, interleukin-lα, interleukin-lβ, interleukin-2, lipopolysaccharides, tetrahydro-L-biopterin and TNF-α. Mention may also be made of L-2-pyrrolidone-5-carboxylic acid and its derivatives, as described in application EP 1 226 822.

Arginase inhibitors

As arginase inhibitors that can be used in

the composition of the invention, mention may be made of: N-omega-hydroxy-nor-L-arginine (nor-NOHA) , aminoboronohexanoic acid (ABH), S-(+)-amino- 5-iodoacetamidopentanoic acid, difluoromethylornithine (DFMO), L-norvaline and S- (2-boronoethyl) -L-cysteine .

NO-releasing agents

Reference is especially made, in the description, to "NO-releasing agents", and in particular to

"nonpolymeric NO-releasing agents", i.e. any NO- releasing agent that is peptide or nonpeptide in nature, i.e. any NO-releasing agent that is peptide or nonpeptide in nature, it being understood that, when the agent is peptide in nature, it comprises from 1 to 5 amino acids, preferably from 2 to 4 amino acids.

The NO-releasing vasodilator compounds may be chemical precursors of NO (subsequently referred to as NO donors) , or may be metabolized and bring about the release of NO via oxidoreduction processes. The NO-releasing vasodilator agents may also generate NO by photoactivation. The release of NO by these compounds can be verified by assaying the byproducts of NO (nitrates and nitrites) released into a liquid medium or by directly measuring the NO gas released on the skin.

The NO-releasing agents that can be used in the invention, which are metabolized to give NO, can be chosen from amino acids, peptides, the proanthocyanidins as described in application JP 2001- 278792, and the cyclic terpenes described in patent application WO 00/044368.

Among the vasodilator amino acids that can be used in the invention, which stimulate NO release by enzymatic action, mention may be made of L-arginine, histidine, lysine, ornithine, glutamic acid, aspartic acid, serine, glycine, cysteine and threonine. Basic, acidic or alcoholic aliphatic amino acids are preferred.

The NO-releasing peptides that can be used in the invention may comprise from 2 to 30 amino acids, for example from 5 to 20 amino acids, and better still from 5 to 15 amino acids. These peptides comprise amino acids such as those described above. Among these NO-releasing peptides, mention may be made of: - L-arginine oligomers (called polyarginine) , oligomers of an L-arginine analogue or of one of their derivatives, such as those described by Exsymol in application EP 1 060 739 and by Essentia in application WO 03/072039, - histidine- and/or alanine-based peptides as described by KS Biomedix Ltd in application WO 02/04005, in particular histidine dipeptides

such as carnosine, anserine and homocarnosine .

Arginine oligomers that are preferred according to the invention comprise from 7 to 15 L-arginine units, for example 7, 9, 11, 13 or 15 L-arginine units. In one embodiment of the invention, the arginine oligomer consists only of arginine. In another embodiment of the invention, however, it may be included in a peptide or polymer that is slightly larger in size and that contains other amino acids (for example, glycine) ; in particular, the arginine oligomer is located at either the C-terminal or N-terminal end of the polymer or of the peptide. An example of such a peptide is gly ₃ -arg ₇ .

The NO donor vasodilator compounds that can be used in the invention can also be chosen from organic compounds which give up NO by chemical reaction, comprising a nitro (-NO2) or nitroso (-NO) substituent, oximes, heterocyclic NO donors, compounds that give nitroxyl, hydroxylamine, nonoate compounds (-N(NO)O ^" ), N-hydroxyguanidine and its salts (such as N-hydroxyguanidine acetate and hydroxyguanidine hemisulphate) , inorganic NO donors, nitrosyl transition metals, nitrosodiphenylamine derivatives, the cyclosine from the Thissen laboratories, SMP-5185 or N-nitratopivaloyl-S- (N' -acetylalanyl) cysteine ethyl ester from the Schwarz Pharma laboratories, photolabile NO donors, guanylate cyclase activators and/or cGMP

stimulators, and molecules developed by the company Nicox, such as NO-flurbiprofen (HCT 1026), NO-hydrocortisone (NCX 1022) and NO-aspirin (NCX 4016) .

Examples of NO donors that can be used in the invention are organic esters of nitric acid, such as ethylene glycol dinitrate, isopropyl nitrate, glyceryl 1-mononitrate, glyceryl 1, 2-dinitrate, glyceryl 1, 3-dinitrate, butane-1, 2, 4-triol trinitrate, erythrityl tetranitrate or pentaerythrityl tetranitrate.

Among the organic compounds comprising a nitro (-NO2) or nitroso (-NO) substituent that can be used in the invention, mention may be made of:

- compounds comprising a nitro or nitroso substituent linked to a carbon atom (C-nitro, C- nitroso) , such as 2-methyl-2-nitrosopropane, ethylene glycol dinitrate, glyceryl 1-mononitrate, glyceryl 1, 2-dinitrate, glyceryl 1, 3-dinitrate, butane-1, 2, 4- triol trinitrate, erythrityl tetranitrate or pentaerythrityl tetranitrate, and organic nitrites such as ethyl nitrite, isobutyl nitrite or isopentyl nitrite (amyl nitrite) ;

- compounds comprising a nitro or nitroso substituent linked to a sulphur atom (S-nitro, S-nitroso) , such as S-nitroso-N-acetylpenicillamine (SNAP) , S-nitrosoglutathione (GSNO) , N-acetyl-S- nitrosopenicillaminyl-S-nitrosopenicillamine,

S-nitrosocysteine, thionitrates or thionitrites (S-nitrosothiols) ;

- compounds comprising a nitro or nitroso substituent linked to an oxygen atom (0-nitroso) , for instance glyceryl trinitrate (GTN) or nitroglycerine, isσsorbide dinitrate (ISDN) , isosorbide 5-mononitrate (IS-5-N) , isopropyl nitrate, isobutyl nitrate, isopentyl nitrate, ethylene glycol dinitrate, glyceryl 1-mononitrate, glyceryl 1, 2-dinitrate, glyceryl 1, 3-dinitrate, butane-1, 2, 4-triol trinitrate, erythrityl tetranitrate, pentaerythrityl tetranitrate, and organic nitrites such as ethyl nitrite, isobutyl nitrite or isopentyl nitrite (amyl nitrite) ;

- compounds comprising a nitro or nitroso substituent linked to a nitrogen atom (N-nitroso) , such as Z\7-nitrosodimethylamine (NDMA) , N-methyl-IV- nitrosourea (NMU), 1, 3-bis (2-chloroethyl) -1-nitrosourea (BCNU) , l-methyl-3-nitro-l-nitrosoguanidine (MNNG) , streptozotocine (STZ) , Λ7-nitroso-.W-phenylhydroxylamine, N-nitrosamines, N-hydroxy-N-nitrosamines, N-nitrosamides, N-nitrosoguanidines, N-nitrosohydrazines or N-nitrosimines .

The NO donors that can be used in the invention can also be chosen from nonoate compounds such as spermine nonoate (Sper/NO) , diethylamine nonoate (DEA/NO) , diethylenetriamine nonoate (DETA nonoate), A^W-bismethyl-l, 6-hexenediamine (MAMA/NO),

N-propyl-1, 3-propanediamine (PAPA/NO), iV-isopropyl- 1, 3-propanediamine, WVN'-bismethyl-l, 3-propanediamine, W _/ N'-bisethylethylenediamine, l-{ [4' ,5' -bis (carboxymethoxy) -2' -nitrophenyl]methoxy}- 2-oxo-3, 3-diethyl-l-triazine or

1- { [ 4 ^f , 5' -bis (carboxymethoxy) -2 ' -nitrophenyl] methoxy} - 2-OXO-3, 3-diethyltriazine .

The NO donors of the oxime chemical family that can be used in the invention are, for example: - (+)-[ (E)-ethyl-2-[ (E) -hydroxyimino] -

5-nitro-3-hexeneamide] ,

- (±) -N- [ (E) -4-ethyl-3 [ (Z) -hydroxyimino] - 5-nitro-3-hexen-l-yl] -3-pyridinecarboxamide .

The NO donors that can be used in the invention can also be chosen from heterocyclic compounds such as :

- sydnonimines, such as molsidomine (MOL) , 3-morpholinosydnonimine (linsidomine, SIN-I) , the W-morpholino-M-nitrosaminoacetonitrile/ γ-cyclodextrin (SIN-lA/gamma CD) complex,

- oxadiazoles (furoxanes) such as 4-phenyl- 3-furoxancarbonitrile,

- oxatriazoles, such as [1, 2, 3, 4-oxatriazolium- 5-amino-3- (3, 4-dichlorophenyl) ] chloride (GEA 3162), [1, 2, 3, 4-oxatriazolium-5-amino-

3- (3-chloro-2-methylphenyl) ] chloride (GEA 5024) or [1, 2, 3, 4-oxatriazolium-3- (3-chloro-

2-methylphenyl) -5- [cyanomethylamino] carboxamido] hydroxide (GEA 5583) , and - diazetidine-di-N-oxide.

The NO donors that can be used in the invention can also be chosen from compounds carrying a nitroxyl (-NO ^" ) substituent, such as benzenesulphohydroxamic acid (Piloty's acid, PA, BSHA), N-acetyl-N-acetoxy-4-chlorobenzenesulphonamide, cyanamide, sodium trioxodinitrate (Angeli's salt) and sodium nitroxyl.

The NO donors that can be used in the invention can also be chosen from inorganic compounds such as nitrosonium salts, nitrosyl halides, nitrite salts, sodium nitrite (NaNθ2) , nitrosyl hydrogen sulphate (NOHSO ₄ ) , nitrosyl chloride (NOCl) , nitrosyl tetrafluoroborate (NOBF ₄ ) , peroxynitrite (ONOO ^" ) and sodium azide (NaNs) . Mention may also be made of inorganic nitrites associated with organic acids such as ascorbic acid or salicylic acid, as described in application WO 99/44622.

The NO donors that can be used in the invention can also be chosen from transition metal complexes with nitrosyl (-NO ⁺ ) as ligand, dinitrosyl- Iron(II) complexes, complexes of nitrosyl with iron- sulphur clusters, complexes of nitrosyl with other transition metals, sodium nitroprusside Na2 [Fe (CN) ₅ N0] , the dinitrosyl-iron-cysteine (1:20) (DNIC) complex and

pentachloronitrosylruthenium (K2 [Ru (NO) CI ₅ ] ) .

Among the photolabile NO donors, mention may in particular be made of the compounds :

- N, N' -dimethyl-N, N' -dinitroso-p-phenylenediamine (BNN3);

- N, N' -dicarboxymethyl-N, N' -dinitroso-p- phenylenediamine, 2Na (BNN5Na) ;

- N, N' -dinitroso-p-phenylenediamine-N, N' -diacetic acid dimethyl ester (BNN5 methyl ester) .

When the agent for promoting the NO production is in molecular form, it can be adsorbed onto or encapsulated in particulate structures having a size that can range from 1 nm to a few μm, for instance microcapsules, microparticles, vesicular dispersions of ionic type (liposomes or oleosomes) and/or nonionic type (niosomes) and/or dispersions of nanospheres.

These particles can be advantageously porous and can consist of silicates or of aluminosilicates . Examples of such formulations are described in particular in documents EP 199 636, EP 375 520, EP 447 318, EP 557 489, WO 97/12602, EP 1 151 741 or US 5 914 126.

By way of example, the microspheres may be prepared according to the method described in patent application EP 0 375 520.

The nanospheres may be in the form of an

aqueous suspension and may be prepared according to the methods described in patent applications FR 0015686 and FR 0101438.

Oleosomes consist of an oil-in-water emulsion formed by oily globules provided with a lamellar liquid crystal coating dispersed in an aqueous phase (see patent applications EP 0 641 557 and EP 0 705 593) .

The agent for promoting the NO production of the composition according to the invention can also be encapsulated in nanocapsules consisting of a lamellar coating obtained from a silicone surfactant as described in document EP 0 780 115; the nanocapsules can also be prepared based on water-dispersible sulphonic polyesters according, for example, to the technique described in patent application FR 0113337.

Preferably, the agent for promoting the NO production is chosen from NO-releasing compounds and NO itself. Preferably, in the composition of the invention, the NO-releasing compounds are chosen from nitroglycerine, S-nitroso-N-acetylpenicillamine (SNAP) , diethylenetriamine nonoate (DETA nonoate) , S-nitrosothiols and SNAGs (nitrosated thiosugars) , sinitrodil, N,N-dimethylhexanediamine (DHMD/NO) , isosorbide dinitrate (ISDN) , trinitrine (GTN) , isosorbide 5-mononitrate (IS5N) and amino acids.

Advantageously, the agent for promoting the NO production is selected from the aamino acids and particularily selected from arginine, lysine or an oligomer of arginine or of lysine.

amino acids

They can be chosen from basic amino acids such as arginine, lysine or histidine and nonpolar natural amino acids such as glycine, alanine, valine, leucine or isoleucine. In particular, the amino acid used is arginine or lysine, or a mixture thereof.

According to a particular form of the invention, the amino acids are in the form of a monomer an oligomer containing from 2 to 30 amino acids, preferably from 5 to 20 amino acids, and better still from 5 to 15 amino acids. It may be in the form of a homooligomer or of an oligomer of several different amino acids (2 or 3) .

The agents for promoting the NO production can be used, in combination with the aminexil, alone or as a mixture, in an amount ranging from 10 ^~2 % to 10% of the total weight of the composition, and preferably in an amount representing from 10 ^~2 % to 5% of the total weight of the composition, for example from 0.5% to 2%. The composition of the invention may be for cosmetic or pharmaceutical use. Preferably, the composition of the invention is for cosmetic use. Thus,

the composition must contain a nontoxic physiologically- acceptable medium that can be applied to the skin, including the scalp and the eyelids, and the integuments such as human keratin fibres. For the purpose of the invention, the term "cosmetic" is intended to mean a composition with a pleasant appearance, odour and feel.

Physiologically acceptable medium Depending on the nature of the vasodilators and/or of the arginase inhibitors, the composition according to the invention can be ingested or applied to the skin or the keratin fibres (to any cutaneous region or fibres to be treated) . It can also be injected. For oral administration, the vasodilator is advantageously an amino acid, and in particular arginine or polyarginine. The agent (s) for p ^A romoting the NO production can be used orally in an amount of from 0.1 to 300 mg per day, 5 to 10 mg/d. A preferred composition of the invention is a composition for cosmetic use and in particular for topical application to the skin and the keratin fibres, and more especially to the scalp, the hair, the nails and the eyelashes. This composition may be in any of the known pharmaceutical forms suitable for the method of use. For topical application to the skin,

including the scalp, the composition may be in the form of an aqueous, alcoholic, aqueous-alcoholic or oily solution or suspension, of an emulsion or dispersion of more or less fluid, and in particular liquid or semi- liquid, consistency, obtained by dispersion of a fatty- phase in an aqueous phase (0/W) or conversely (W/0) , of a solid dispersion or emulsion (0/W) or (W/0) , of a more or less fluid or solid aqueous, aqueous-alcoholic or oily gel, of a loose or compacted powder to be used as it is or to be incorporated into a physiologically acceptable medium, or else of microcapsules or microparticles, or of vesicular dispersions of ionic and/or nonionic type.

A composition in the form of a foam or else in the form of a spray or of an aerosol, then comprising a pressurized propellant, can also be envisaged.

The composition may thus be in the form of a lotion, serum, milk, 0/W or W/0 cream, gel, salve, ointment, powder, balm, patch, impregnated pad, soap, cake or foam.

In particular, the composition for application to the scalp or the hair may be in the form of a haircare lotion, for example to be applied daily or twice-weekly, of a shampoo or a hair conditioner, in particular to be applied twice-weekly or weekly, of a liquid or solid scalp cleansing soap to be applied

daily, of a hairstyle shaping product (lacquer, hair setting product or styling gel) , of a treatment mask, or of a foaming gel or cream for cleansing the hair. It may also be in the form of a hair dye or mascara to be applied with a brush or a comb.

Moreover, for application to the eyelashes or body hairs, the composition to which the invention applies may be in the form of a pigmented or unpigmented mascara, to be applied with a brush to the eyelashes or alternatively to beard or moustache hair. For a composition for use by injection, the composition may be in the form of an aqueous lotion or an oily suspension, for example in the form of serum. For oral use, the composition may be in the form of capsules, of granules, of oral syrups or of tablets.

According to a particular embodiment, the composition according to the invention is in the form of a hair cream or hair lotion, of a shampoo or a conditioner for the hair, or of a mascara for the hair or the eyelashes.

The amounts of the various constituents of the physiological medium of the composition according to the invention are those generally used in the fields under consideration. Furthermore, these compositions are prepared according to the usual methods.

When the composition is an emulsion, the proportion of the fatty phase may range from 2% to 80%

by weight, and preferably from 5% to 50% by weight, relative to the total weight of the composition. The aqueous phase is adjusted as a function of the content of fatty phase and of compound (s) (A) and also of that of the optional additional ingredients, so as to obtain 100% by weight. In practice, the aqueous phase represents from 5% to 99.9% by weight.

The fatty phase may contain fatty or oily compounds that are liquid at ambient temperature (25°C) and atmospheric pressure (760 mmHg) , which are generally known as oils. These oils may be compatible or incompatible with one another and may form a macroscopically homogeneous liquid fatty phase or a two-phase or three-phase system. In addition to the oils, the fatty phase may contain waxes, gums, lipophilic polymers or "pasty" or viscous products containing solid parts and liquid parts .

The aqueous phase contains water and, optionally, an ingredient that is miscible in any proportion with water, for instance Ci to C ₈ lower alcohols such as ethanol or isopropanol, polyols, for instance propylene glycol, glycerol or sorbitol, or alternatively acetone or ether. The emulsifiers and co-emulsifiers used for obtaining a composition in the form of an emulsion are those generally used in the cosmetics and

pharmaceutical fields. Their nature also depends on the sense of the emulsion. In practice, the emulsifier and, optionally, the co-emulsifier are present, in the composition, in a proportion ranging from 0.1% to 30% by weight, preferably from 0.5 to 20% by weight, and better still from 1 to 8%. The emulsion may also contain lipid vesicles, and especially liposomes.

When the composition is in the form of an oily solution or gel, the fatty phase may represent more than 90% of the total weight of the composition.

Advantageously, the composition is an aqueous, alcoholic or aqueous-alcoholic solution or suspension, and better still a water/ethanol solution or suspension. The alcoholic fraction may represent from 5% to 99.9%, and better still from 8% to 80%.

For a mascara application, the composition is a wax-in-water or wax-in-oil dispersion, a gelled oil or an aqueous gel, which may be pigmented or unpigmented. Additional features of the invention

The composition of the invention may also comprise other ingredients normally used in the fields concerned, chosen from solvents, aqueous-phase or oily- phase thickeners or gelling agents, dyestuffs that are soluble in the medium of the composition, solid particles of the filler or pigment type, antioxidants, preserving agents, fragrances, electrolytes,

neutralizers, UV blockers, for instance sunscreens, film-forming polymers, cosmetic and pharmaceutical active agents with a beneficial effect on the skin or integuments, and in particular keratin fibres (such as vitamins), and mixtures thereof. These additives may be present in the composition according to the amounts generally used in the cosmetics and dermatological field, and in particular in a proportion of from 0.01 to 50% of the total weight of the composition, and better still from 0.1 to 20%, and for example from 0.1 to 10%. Depending on their nature, these adjuvants may ^¬ be introduced into the fatty phase, into the aqueous phase and/or into the lipid vesicles, and especially liposomes . Of course, those skilled in the art will take care to select the optional complementary additives and/or the amount thereof in such a way that the advantageous properties of the composition according to the invention, in particular namely the increase in the density of keratin fibres, are not, or are not substantially, impaired by the envisaged addition.

As solvents that can be used in the invention, mention may be made of C ₂ to Cs lower alcohols, for instance ethanol, isopropanol, propylene glycol and certain light cosmetic oils, for instance Ce to C16 alkanes.

As oils that can be used in the invention,

mention may be made of oils of mineral origin (liquid petroleum jelly, hydrogenated isoparaffin) , oils of plant origin (liquid fraction of shea butter, sunflower oil, apricot oil, soybean oil, fatty alcohol or fatty acid) , oils of animal origin (perhydrosqualene) , synthetic oils (fatty acid esters, purcellin oil) , silicone oils (linear or cyclic polydimethylsiloxanes, phenyl trimethicones) and fluoro oils (perfluoropolyethers) . As waxes, mention may be made of silicone waxes, beeswax, candelilla wax, rice wax, carnauba wax, paraffin wax or polyethylene wax.

As emulsifiers that can be used in the invention, mention may, for example, be made of glyceryl stearate, glyceryl laurate, sorbitol stearates, sorbitol oleates, alkyl dimethicone copolyols (with alkyl ≥ 8) and mixtures thereof for a W/0 emulsion. Polyethylene glycol monostearate or monolaurate, polyoxyethylenated sorbitol stearate or oleate, and dimethicone copolyols, and mixtures thereof, can also be used for an 0/W emulsion.

As hydrophilic gelling agents that can be used in the invention, mention may be made of carboxyvinyl polymers (carbomer) , acrylic copolymers such as acrylate/alkyl acrylate copolymers, polyacrylamides, polysaccharides such as hydroxypropyl cellulose, natural gums and clays, and as lipophilic gelling agents, mention may be made of modified clays,

for instance bentones, metal salts of fatty acids, for instance aluminium stearates, hydrophobic-treated silica and ethylcellulose, and mixtures thereof.

The composition may contain an additional active agent other than those mentioned above, which may be hydrophilic and chosen from proteins or protein hydrolysates, amino acids, polyols, urea, allantoin, sugars and sugar derivatives, water-soluble vitamins, plant extracts (those from Iridacea plants or from soybean) and hydroxy acids (fruit acid, salicylic acid) ; or lipophilic and chosen from retinol (vitamin A) and its derivatives, especially an ester (retinyl palmitate) , tocopherol (vitamin E) and its derivatives, especially an ester (tocopheryl acetate or palmitate) , essential fatty acids, ceramides, essential oils, salicylic acid derivatives, for instance 5-n-octanoylsalicylic acid, hydroxy acid esters, and phospholipids, for instance lecithin, and mixtures thereof . According to a particular embodiment of the invention, it is possible to combine with the above combination, at least one additional compound that promotes hair regrowth and/or limits hair loss. These additional compounds are in particular chosen from the lipoxygenase inhibitors as described in EP 0648488, the bradykinin inhibitors described in particular in EP 0845700, anti-androgenic agents, cyclosporines and

analogues thereof, antimicrobial agents and antifungal agents, anti-inflammatories and retinoids, alone or as a mixture .

The anti-androgenic agents that can be used include in particular steroidal or non-steroidal inhibitors of 5α-reductase, such as finasteride and the compounds described in US 5 516 779, cyprosterone acetate, azelaic acid, its salts and its derivatives and the compounds described in US 5 480 913, flutamide, the compounds described in US patents 5 411 981, 5 565 467 and 4 910 226, and also oxendolone, spironolactone, diethylstilbestrol and flutamide.

The antimicrobial or antifungal compounds can be chosen from selenium derivatives, ketoconazole, octopirox, triclocarban, triclosan, zinc pyrithione, itraconazole, metronidazole, crotamiton or pyrethrinoids, asiatic acid, hinokitiol, mipirocine, tetracyclines, especially erythromycin and the compounds described in EP 0680745, clinycin hydrochloride, benzoyl peroxide or benzyl peroxide, minocycline and compounds belonging to the imidazole class, such as econazole, ketoconazole or miconazole or salts thereof, nicotinic acid esters, including especially tocopheryl nicotinate, benzyl nicotinate and C _x -C ₆ alkyl nicotinates, for instance methyl nicotinate or hexyl nicotinate.

The anti-inflammatories can be chosen from

steroidal anti-inflammatories, for instance glucocorticoids, corticosteroids (for example: hydrocortisone) , and non-steroidal anti-inflammatories, for instance glycyrrhetinic acid and α-bisabolol, benzydamine, and the compounds described in EP 0770399, WO 94/06434 and FR 2268523.

The retinoids may be chosen from retinoic acid, isotretinoin, acitretin and tazarotene.

As other additional active compounds for promoting hair growth and/or limiting hair loss that can be used in the composition according to the invention, mention may be made of 6-0- [ (9Z, 12Z) - octadeca-9, 12-dienoyl] hexapyranose, benzalkonium chloride, benzethonium chloride, phenol, oestradiol, chlorpheniramine maleate, chlorophylline derivatives, cholesterol, cysteine, methionine, menthol, peppermint oil, calcium pantothenate, panthenol, resorcinol, protein kinase C activators, glycosidase inhibitors, glycosaminoglycanase inhibitors, pyroglutamic acid esters, hexosaccharide or acylhexosaccharide acid, substituted arylethylenes, N-acylamino acids, flavonoids, ascomycin derivatives and analogues, histamine antagonists, saponins, proteoglycanase inhibitors, oestrogen agonists and antagonists, pseudoterines, cytokines, growth factor promoters, inhibitors of IL-I or of IL-6, IL-IO promoters, TNF inhibitors, benzophenones and hydantoin; vitamins, for

instance vitamin D, vitamin B12 analogues and pantothenol; triterpenes, for instance ursolic acid and the compounds described in US 5 529 769, US 5 468 888 and US 5 631 282; antipruriginous agents, for instance thenaldine, trimeprazine or cyproheptadine; hormones such as oestriol or analogues thereof, thyroxine and salts thereof, progesterone; FP receptor (type F prostaglandin receptor) agonists such as latanoprost, bimatoprost, travoprost or unoprostone; 15-hydroxyprostaglandin dehydrogenase inhibitors; mixtures thereof.

It may also be envisaged for the composition for topical application, comprising aminexil and/or a vasodilator and/or an amino acid and/or an arginase inhibitor, to be encapsulated and in particular in liposomal form, as in particular described in document WO 94/22468. Thus, the compound encapsulated in the liposomes can be delivered selectively to the hair follicle . The composition according to the invention may be applied to the alopecia-affected areas of the scalp and the hair of an individual, and optionally left in contact for several hours and optionally rinsed off. The composition may, for example, be applied in the evening, kept in contact throughout the night and optionally shampooed out in the morning. These

applications can be repeated daily for one or more months according to the individual .

Advantageously, in the process according to the invention, between 5 and 500 μl of a solution or composition as defined above are applied to the areas of the scalp to be treated.

EXAMPLE

EXAMPLE : Hair lotion - Aminexil 0.5O g

- Arginine oligomer (7 monomers) 0.5 g

- Propylene glycol 30.00 g

- Ethyl alcohol 40.00 g

- Water qs 100.00 g This lotion is applied to the scalp once or twice a day, in a proportion of 1 ml per application, by lightly massaging the scalp so as to cause the active agent to penetrate. The head of hair is subsequently dried in the open air. This lotion makes it possible to decrease hair loss and to promote regrowth thereof.