Compositions for the Pigmentation of the Skin or of the Hair Containing an Extract of Marrubium Vulgare, the Process for It's Manufacture and It's

The present invention relates essentially to a cosmetic or pharmaceutical composition, especially dermatological composition, containing an extract of Marrubium vulgare, intended in particular for promoting the pigmentation of the skin or hair, and to the process for its manufacture.

The present invention further relates to the use of an extract of Marrubium vulgare for the preparation of such a cosmetic or pharmaceutical composition intended in particular for treating pigmentation disorders.

The various species of the genus Marrubium vulgare belong to the family of the Labiatae. Marrubium vulgare, also called white horehound, is commonly found in uncultivated locations, especially in Mediterranean regions and also in West Asia and North Africa.

According to tradition, the leaves and flowering tops of this plant possess expectorant and fluidifying properties towards bronchial secretions. It is also said to have an effect on extrasystolic arrhythmia (see, in particular, Precis de Matiere Medicale (Precis of Medical Topics) by R. R. PARIS and Mme H. MOYSE, volume III, published by MASSON et Compagnie, 1971, page 293).

The present invention is based on the discovery that extracts of Marrubium vulgare, in particular those originating from the aerial parts and especially from the stems and leaves, have valuable biological properties which can be utilized in the cosmetic and pharmaceutical fields. In particular, the inventors have observed that these extracts unexpectedly possess a melanogenesis-stimulating activity on the melanocytes present in the skin or the hair follicles, especially those on the scalp, and thus make it possible to promote the pigmentation of the skin or hair as well as to treat pigmentation disorders of the skin and hair, more particularly by promoting the biosynthesis of melanin. Very good results in this field have been obtained with extracts of the aerial parts of Marrubium vulgare, in particular the stems and leaves.

One object of the present invention is therefore to solve the new technical problem which consists in providing a novel cosmetic or pharmaceutical composition, especially dermatological composition, intended in particular for promoting the pigmentation of the skin and preventing or slowing down the appearance of white hair.

A further object of the present invention is to solve the new technical problem which consists in preparing a novel formulation of a cosmetic or pharmaceutical composition having a good melanogenesis-stimulating activity on the melanocytes present in the skin or the hair follicles, especially those on the scalp.

A further object of the present invention is to provide a solution to the new technical problem which consists in providing a particularly easily obtainable plant extract which in itself has a good melanogenesis-stimulating activity on the melanocytes present in the skin or the hair follicles, without having to isolate an active substance of any kind, these isolation processes generally being lengthy and expensive.

All these new technical problems are solved for the first time by the present invention in a satisfactory manner which can be used on the industrial scale.

Thus, according to a first feature, the present invention relates to a cosmetic or pharmaceutical composition, especially dermatological composition, intended in particular for promoting the pigmentation of the skin and preventing or slowing down the appearance of white hair, said composition comprising, as the active ingredient, a cosmetically or pharmaceutically effective amount of an extract of Marrubium vulgare, if appropriate in a cosmetically or pharmaceutically acceptable excipient.

In the present description and the claims, "cosmetically or pharmaceutically effective amount" is understood as meaning an amount at least equal to the minimum amount which is necessary for observing a significant cosmetic or pharmaceutical effect.

According to one particular characteristic of the invention, the extract of Marrubium vulgare is an extract of the aerial parts, in particular the stems and leaves.

According to another characteristic, the above-mentioned extract of Marrubium vulgare is an organic extract, in particular of the aerial parts such as the stems and leaves, which is advantageously obtained by a process comprising at least one extraction step, for example with a solvent selected from the group consisting of water, alcohols preferably containing from 1 to 4 carbon atoms, such as methanol, ethanol or propanol, an aqueous-alcoholic mixture of these alcohols, chlorinated solvents containing 1 or 2 carbon atoms, such as chloroform or dichloromethane, and organic esters preferably containing 3 to 6 carbon atoms, such as ethyl acetate. More generally, other solvents which can be used are organic solvents such as aromatic hydrocarbons, especially benzene, toluene or xylene, halogenated aliphatic or aromatic hydrocarbons, dialkyl ethers, dialkyl ketones, alkanols, carboxylic acids and esters thereof, or other solvents such as dimethylformamide, dioxane, tetrahydrofuran and dimethyl sulfoxide. The ratio of plant material to extraction agent is not critical but is generally between 1:5 and 1:20 parts by weight, preferably about 1:10. The extraction is carried out at temperatures between room temperature and the boiling point of the solvent used for the extraction. A valuable extraction technique is the so-called Soxhlet extraction technique.

However, it is also possible simply to carry out the extraction under reflux at normal atmospheric pressure for 2 to 4 h, if appropriate after the plant material has been left to macerate for 2 to 4 h in the cold extraction solvent.

When the extraction is complete, the phase containing the extract is filtered and then concentrated and/or evaporated to dryness under reduced pressure or by lyophilization.

This gives an extract according to the invention.

In general, the concentration of the extracts used according to the present invention for the preparation of a cosmetic or pharmaceutical composition, expressed by dry weight, is between 0.0001% and 5% by weight, preferably between 0.01% and 0.5% by weight, based on the total weight of the composition.

The cosmetic or pharmaceutical compositions, especially dermatological compositions, according to the present invention can be prepared in forms suitable for various modes of administration. In particular, they can be presented in a form intended for surface administration to the skin or scalp, such as a cream, a gel, a milk or a lotion, in order to promote the pigmentation of the skin and prevent or slow down the appearance of white hair.

Thus the cosmetic or pharmaceutical compositions, especially dermatological compositions, according to the invention have various applications in cosmetology or pharmacy, especially in dermatology, in particular when it is desired to restore normal pigmentation or increase this pigmentation.

For example, these compositions can be used as sun products for accelerating or intensifying tanning, which, in addition to the aesthetic advantage often sought after, makes it possible to strengthen the natural defenses against ultraviolet radiation by increasing the proportion of melanin in the epidermis. These compositions can also be used in the form of creams, for example, in order to give the skin a more sunburnt appearance, or else in the form of lotions in order to prevent or slow down the appearance of white hair. Furthermore, in dermatology, the compositions according to the present invention can be used as therapeutic agents, either by themselves or in association with other medicaments, in particular by topical administration in the treatment of dysfunctions of the melanocytes.

Advantageously, the cosmetic or pharmaceutical compositions according to the invention which are intended for topical administration contain at least one agent for promoting penetration and diffusion in the cutaneous structures in question, such as the agents commonly used in the fields of cosmetology and dermopharmacy, for example glycerol, propylene glycol, oleic acid or essential oils, especially menthol and eucalyptol.

In one advantageous embodiment, a cosmetic or pharmaceutical composition according to the invention also contains a xanthine, in particular 1-methylxanthine, 3-methylxanthine, 3-isobutylmethylxanthine or theophylline, preferably at a concentration by weight of between 0.001% and 2% and particularly preferably of between 0.01% and 0.5%, based on the total weight of the composition.

In another embodiment, applicable in particular within the framework of activating the pigmentation of the skin or hair, a cosmetic or pharmaceutical composition according to the invention also contains tyrosine or a derivative thereof, such as glucose tyrosinate or N-malyltyrosine, preferably at a concentration by weight of between 0.001% and 10%, based on the total weight of the composition.

In yet another embodiment, applicable in particular within the framework of activating the pigmentation of the hair, a cosmetic or pharmaceutical composition according to the invention also contains an effective concentration of at least one other active substance selected from vitamins, in particular the B vitamins, quinine or derivatives thereof, rubefacients such as methyl nicotinate, a papilla fibroblast culture supernatant as defined in the document EP-A-272 920, keratin hydrolyzates, trace elements such as zinc, selenium and copper, 5-.alpha.-reductase inhibitors such as progesterone, cyproterone acetate and minoxidil, azelaic acid and derivatives thereof, a 1,4-dimethyl-4-azasteroid, in particular 17-.beta.-N,N-diethylcarbamoyl-4-methyl-4-aza-5-.alpha.-androstan-3-one, or else an extract of Serenoa repens.

In yet another embodiment, a cosmetic or pharmaceutical composition according to the invention also contains hydrated lipidic lamellar phases or liposomes, which may or may not incorporate the extract of Marrubium vulgare defined above.

According to a second feature, the present invention further relates to a process for the manufacture of a cosmetic or pharmaceutical composition, especially dermatological composition, intended in particular for promoting the pigmentation of the skin, preventing or slowing down the appearance of white hair and treating pigmentation disorders of the skin or hair, said process comprising the incorporation of at least one extract of Marrubium vulgare, as defined above, into a cosmetically or pharmaceutically acceptable excipient, vehicle or carrier.

According to a third feature, the invention relates to the use of an extract of Marrubium vulgare, as defined above, for the preparation of a cosmetic or pharmaceutical composition, especially dermatological composition, intended in particular for promoting the pigmentation of the skin, preventing or slowing down the appearance of white hair or treating pigmentation disorders of the skin or hair.

According to yet another feature, the present invention further relates to a cosmetic or therapeutic method of treating a pigmentation insufficiency or pigmentation disorders, said method comprising the application of an effective amount of at least one extract of Marrubium vulgare, as defined above, advantageously incorporated in a cosmetically or pharmaceutically acceptable excipient, vehicle or carrier, preferably to the affected areas of the skin or scalp of a human being, in order to restore normal pigmentation of the skin or hair and/or increase this pigmentation.

In all the foregoing features, the extract of Marrubium vulgare, as defined above, can be used in the presence of hydrated lipidic lamellar phases or liposomes, which may or may not incorporate said extract. It is pointed out that the expression "incorporate" covers the case where the extract is totally incorporated and the case where only a certain amount of this extract is incorporated in the hydrated lipidic lamellar phases or the liposomes.

The term "lipidic" in the expression "lipidic lamellar phase" covers all substances which comprise a so-called fatty hydrocarbon chain generally containing more than 5 carbon atoms, this substance usually being called a "lipid".

According to the invention, the lipids used to form the lipidic lamellar phases or the liposomes are amphiphilic lipids, i.e. lipids consisting of molecules which possess either an ionic or a non-ionic hydrophilic group and a lipophilic group, these amphiphilic lipids being capable of forming lipidic lamellar phases or liposomes in the presence of an aqueous phase, depending on the amount of water in the mixture.

The following may be mentioned in particular among these lipids: phospholipids, phosphoaminolipids, glycolipids, polyoxyethylenated fatty alcohols and optionally polyoxyethylenated polyol esters. Such substances consist for example of an egg or soya lecithin, a phosphatidylserine, a sphyngomyelin, a cerebroside or an oxyethylenated polyglycerol stearate.

It is preferable according to the invention to use a mixture of lipids made up of at least one amphiphilic lipid and at least one hydrophobic lipid such as a sterol like cholesterol or .beta.-sitosterol. The amount of hydrophobic lipid, expressed in mol, must not generally exceed the amount of amphiphilic lipid and preferably must not exceed 0.5 times this amount.

The compounds or the extracts containing these compounds used according to the present invention can be incorporated into hydrated lipidic lamellar phases or into liposomes by known preparative techniques described for example in the document EP-B1-0 087 993 =U.S. Pat. No. 4,508,703, if appropriate in combination with the document EP-B1-0 107 559 = U.S. Pat. No. 4,621,023.

Other objects, characteristics and advantages of the invention will become clearly apparent from the following explanatory description referring to several Examples, which are given simply by way of illustration.

In fact, the present invention is in no way limited to the embodiments described and illustrated. Thus, for example, it also covers a cosmetic or dermatological composition intended for preventing the eyebrows or eyelashes from turning white or for slowing down this process.

The percentages are given by weight in the Examples, unless indicated otherwise.

500 g of aerial parts of Marrubium vulgare, composed of stems and leaves, are refluxed for 3 h with about 5 l of methanol.

The methanolic extracts are filtered and the filtrate is evaporated under reduced pressure and then lyophilized to give a methanolic extract of Marrubium vulgare called extract I.sub.1.

An ethyl acetate extract of Marrubium vulgare called extract I.sub.2 is obtained by following the procedure described in Example 1, except that the whole plant is used and ethyl acetate is used as the solvent.

An extract of aerial parts of Marrubium vulgare obtained according to Example 1 is incorporated into hydrated lipidic lamellar phases or into liposomes by the following preparative technique:

The following are weighed out:

soya lecithin: 1.8 g

.beta.-sitosterol: 0.2 g

lyophilized extract of Marrubium vulgare I.sub.1 of Example 1: 0.03 g

These constituents are dissolved in a mixture made up of 25 ml of dichloromethane and 10 ml of methanol.

The resulting mixture is evaporated on a rotary evaporator at a temperature of 60.degree. C. under reduced pressure.

The resulting lipidic film is then taken up and dispersed in distilled water qsp 50 g at room temperature for 12 h, with agitation.

The suspension of lipidic vesicles obtained is then homogenized by treatment with ultrasound for 10 min at 4.degree. C., at a power of 150 W.

The resulting liposomes have a mean size of about 140 nm.

In one advantageous variant, this suspension is then gelled by being mixed with 50 g of 1.25% Carbopol.RTM. 940 gel, separately prepared in conventional manner. This gives about 100 g of a gelled suspension of liposomes encapsulating the extract of Marrubium vulgare, the concentration of which is about 0.030%, based on the total weight of the suspension.

This gel is called "composition I.sub.3 " and can be used as such within the framework of the invention.

Protocol:

S91 murine melanocytes, inoculated at a rate of 2.multidot.10.sup.5 cells per dish, are cultivated in EMEM complemented with non-essential amino acids and also containing 1% of fetal calf serum and 0.08 .mu.g/ml of mitomycin C. 24 h after inoculation, the culture medium is replaced with fresh medium free of mitomycin C and comprising only complemented EMEM, 1% of fetal calf serum and, if appropriate, the test product solubilized in DMSO.

Six days after inoculation, the cells are removed and isolated by centrifugation and the cellular residue is recovered and dissolved in 0.5N sodium hydroxide.

The optical density of the solution obtained is read on a spectrophotometer at 405 nm, which makes it possible to evaluate the amount of melanin formed by comparison with the optical density of a solution of melanin of known concentration.

The cells are also counted and the amount of melanin formed per 10.sup.6 cells is calculated.

Extracts I.sub.1 and I.sub.2 of Marrubium vulgare were tested, at various concentrations, using as positive control a culture receiving only .beta.-MSH (melanocyte-stimulating hormone) at a concentration of 2.multidot.10.sup.-8 M.

The melanogenesis-stimulating efficacy E of the test products is calculated by means of the following formula: ##EQU1## in which the quantities q represent the amounts of melanin formed per 10.sup.6 cells:

q.sub.p : culture receiving the test product

q.sub.t : culture receiving .beta.-MSH

q.sub.o : control culture receiving no product

The efficacy E of the extracts tested at different concentrations, calculated according to the above formula, is shown

a) in Table I below for extract I.sub.1 of Example 1, or

b) in Table II below for extract I.sub.2 of Example 2.

The tests were performed with three dishes per concentration and per product, so the values shown in Tables I and II, relating to the number of cells per dish and to the amount of melanin, are mean values.

A statistical study by the Student t test compares the results of the control cultures with those of the cultures treated with the products according to the invention or with .beta.-MSH.

S = significant at 5%,

NS = not significant at 5%.

Tables I and II above show that the extracts according to the invention stimulate the production of melanin to a significant extent, representing a totally unexpected result for those skilled in the art.

Various Examples of the formulation of cosmetic or pharmaceutical compositions, especially dermatological compositions, are given below.

Apply the lotion to the hair at a rate of 1 ml twice a day for 6 months to obtain a significant pigmenting effect.

The gel is prepared from the following two phases A and B:

Phase A is added gradually to phase B and the components are mixed with a propeller mixer until dispersion is complete.

This gives a gel for promoting tanning of the skin, which can be applied before or during exposure to the sun.