WO2008034703A1

WO2008034703A1 - Obtaining a controlled coloured effect from a vegetable extract

Info

Publication number: WO2008034703A1
Application number: PCT/EP2007/059016
Authority: WO
Inventors: Véronique Chevalier; Quang Lan Nguyen
Original assignee: L'oreal
Priority date: 2006-09-20
Filing date: 2007-08-29
Publication date: 2008-03-27

Abstract

The invention relates to a method of preparation of a vegetable extract, characterized in that it comprises (1) a stage of percolation of fluid under pressure through at least one vegetable substance in the form of solid or paste, and (2) the use of a catalytic mixture comprising (i) a first constituent selected from the salts and oxides of Mn(II) and/or of Zn(II) and mixtures thereof, and (ii) a second constituent selected from the alkali-metal hydrogen carbonates, the alkaline-earth hydrogen carbonates and mixtures thereof, the catalytic mixture being either contained in the percolation fluid or added to the extract obtained after the percolation stage. The extract obtained can be used 'as is' on keratinous materials such as the skin, or incorporated in a composition before being applied to the keratinous material.

Description

Obtaining a controlled coloured effect from a vegetable extract

The present invention relates to a method of preparation of a vegetable extract which makes it possible to obtain a controlled coloured effect on the skin. The invention further relates to the extract obtained, and its use for the treatment of keratinous materials, in particular the skin and human keratin fibres such as the hair, as well as a composition containing said extract.

In cosmetics, we are constantly trying to improve the cosmetic properties of keratinous materials. Thus, the use of actives and notably of vegetable extracts in cosmetic compositions is known, for maintaining the skin in good condition or for improving the condition of the skin, notably by fighting against the signs of ageing of the skin, and by supplying the skin and other keratinous materials treated with these compositions all the beneficial effects associated with these vegetable extracts.

It is known that, in the course of the ageing process, various signs appear on human skin, which are very characteristic of said ageing, notably in the form of a change in skin structure and skin function. The main clinical signs of skin ageing are notably the appearance of lines and then of deep wrinkles, increasing with age, and disturbance of the "grain" of the skin, i.e. the micro-relief becomes less regular and displays an anisotropic character.

Furthermore, the complexion generally changes; it appears paler and more yellowish, which seems to be due essentially to a disturbance of the microcirculation (less haemoglobin in the papillary dermis). In addition, coloured spots appear on the surface, owing to altered melanogenesis. Another clinical sign of ageing is rough, dry appearance of the skin, due essentially to increased desquamation, with the resultant scales diffracting the light rays and thus contributing to the greyish appearance of the complexion.

The use of cosmetic or dermatologic compositions containing, among other actives, vegetable extracts containing polyphenols, which notably improve the radiance of the complexion and may give a coloured effect on the skin, is known for treating these signs of ageing.

However, natural vegetable extracts containing polyphenols generally have a low concentration of polyphenols and are unstable, and it is known that it is necessary to stabilize them when they are included in a cosmetic composition.

This stabilization is difficult, however, and generally the proportion of polyphenol originally present in a composition decreases considerably during storage of the composition, leading to the formation of by-products and the appearance of coloration that is neither desired nor desirable, and which is difficult to control, both in colour and in intensity. Moreover, it is advantageous that the polyphenol extracts are stable in the course of their storage prior to use, but are able to undergo oxidation readily when applied to the skin. Oxidation brings about their destabilization, which is in contradiction to the desired stability, moreover; however, when they undergo oxidation on the skin, the polyphenols endow the skin with a coloration, giving it an effect of looking well, and a tan similar to a mild suntan.

There is therefore a need for vegetable extracts containing polyphenols, which do not denature over time, but remain stable, while being active when applied to the skin, and which allow a controlled coloured effect to be obtained on the skin. A "controlled effect" is an effect which appears only on application to the skin and not before application to the skin. This effect may be a coloration or a tanning of the skin.

The applicant discovered, surprisingly, that by using a percolation method in combination with a special catalytic mixture, it was possible to obtain aqueous vegetable extracts that are stable and therefore no longer have the drawbacks mentioned above, yet still have very good activity on the skin. In fact, using the method of the invention, the polyphenols contained in the vegetable substances are much more available after percolation, and the extract obtained, in mixing at the time of use with the catalytic mixture, makes the polyphenols oxidizable on the skin, thereby endowing the skin with a coloration whose intensity is dependent on the vegetable extracts used and on their concentration in the final composition.

Thus, the invention relates to a method of preparation of a vegetable extract, characterized in that it comprises (1 ) a stage of percolation of fluid under pressure through at least one vegetable substance in the form of solid or paste, yielding an extract, and (2) the use of a catalytic mixture comprising (i) a first constituent selected from the salts and oxides of Mn(II) and/or of Zn(II) and mixtures thereof, and (ii) a second constituent selected from the alkali-metal hydrogen carbonates, the alkaline-earth hydrogen carbonates and mixtures thereof, the catalytic mixture being either contained in the percolation fluid of stage (1 ), or added to the extract obtained after percolation.

The vegetable substance can come from the wood, leaves, grasses, flowers, fruits, roots, bark or rind, pulp, peel, berries, beans and seeds of plants.

The vegetable extract prepared according to the method of the invention is an aqueous extract and it must be usable directly in topical application, in particular on keratinous materials, and it therefore contains a physiologically acceptable medium. "Physiologically acceptable medium" means a medium that is non-toxic, that can be applied to keratinous materials, and which is pleasant to use. By keratinous materials, we mean the skin, the scalp, the lips, and/or the integumentary appendages such as the nails, the eyelashes, the eyebrows and the hair. The extract obtained by the method according to the invention can be used directly and can constitute a cosmetic or dermatologic composition, or it can be added to a composition that will then constitute the topical, notably cosmetic or dermatologic, composition.

The vegetable substances prior to their percolation are stable because they are in solid or pasty form, and the extracts obtained according to the invention contain a high concentration of polyphenols which are activated by the catalytic mixture at the time of application to the skin.

The method according to the invention can be carried out in two ways: - either the catalytic mixture is present in the percolation fluid before percolation;

- or the catalytic mixture is added to the extract obtained after percolation.

An important advantage of the method of preparation is that vegetable extracts are obtained that impart good cosmetic properties to keratinous materials, owing to their high concentration of polyphenols and good activity when applied to the skin.

The invention also relates to the cosmetic use of the extract obtained according to the method of the invention, for the cosmetic treatment of keratinous materials, particularly in order to give the skin an effect of looking well. The extract may in particular be used as a self-tanning product and/or in a self- tanning composition.

The invention relates in particular to the cosmetic use of the extract obtained according to the method defined above, for the purpose of imparting a coloration or a tan to the skin.

The invention finally relates to a composition containing the extract obtained by the method according to the invention.

Other aims, characteristics, aspects and advantages of the invention will become clearer on reading the description and the examples given below.

Percolation method

The percolation method is carried out according to the usual technique of percolation. A fluid at a temperature preferably greater than or equal to 30 °C, preferably ranging from 30°C to 150°C, and more preferably ranging from 40°C to 120°C, under a pressure preferably of at least 3 bar (3.10⁵ Pa), for a very short time, less than one minute, is passed through at least one vegetable substance in the form of solid or paste, preferably in the form of a solid, and more preferably in the form of powder. The percolation stage leads to the production of a vegetable extract that can be ready to use directly, if the percolation fluid contained the catalytic mixture. Otherwise, the extract obtained after percolation is mixed with the catalytic mixture, and a stabilized vegetable extract is obtained. It is generally used quickly after it is obtained, for example within 5 minutes after being obtained, notably after cooling to a physiologically acceptable temperature, preferably below 60 °C. However, said extract can be used up to a week after it is produced.

Since the preparation time is very short, the vegetable extracts obtained by the method described above and the cosmetic compositions containing them can be prepared "as required" by mixing together the vegetable extracts and other actives depending on the desired cosmetic properties.

According to another embodiment, the vegetable substances can be packaged in a ready-to-use kit, and it is not necessary to determine beforehand the concentrations of the vegetable substances in solution, which limits measurement errors on the part of the user.

Moreover, the method according to the invention avoids the use of multi- compartment bottles, making the method particularly economical and more reliable for the user.

Percolation is the movement of fluid through a saturated porous medium that permits passage of the fluid, under the action or the effect of pressure.

The fluid can comprise steam, optionally accompanied by liquid water, or one or more physiologically acceptable liquid and/or gaseous, notably organic, solvents, or a mixture of steam optionally accompanied by liquid water, and one or more physiologically acceptable liquid and/or gaseous solvents. Preferably, the fluid comprises at least steam, which may be accompanied by liquid water, and more preferably it is steam, which may be accompanied by liquid water.

As organic solvent, we may mention for example the CrC₄ alcohols, such as ethanol and isopropanol; the polyols and ethers of polyols such as 2- butoxyethanol, propylene glycol, monomethylether of propylene glycol, monoethylether and monomethylether of diethylene glycol, as well as the aromatic alcohols such as benzyl alcohol or phenoxyethanol, and mixtures thereof.

Moreover, according to a particular embodiment of the invention, the percolation fluid contains the catalytic mixture comprising (i) a first constituent selected from the salts and oxides of Mn(II) and/or of Zn(II) and mixtures thereof, and (ii) a second constituent selected from the alkali-metal hydrogen carbonates, the alkaline-earth hydrogen carbonates and mixtures thereof. This catalytic mixture can be prepared from the constituents described hereunder and added to the percolation fluid, which can be, for example, purified or demineralized water, or alternatively the catalytic mixture may be present naturally in bicarbonate mineral waters rich in salts of manganese or of zinc, for example Vichy waters (Lucas, Hόpital, Grande-Grille springs); Roche Posay water, Avene water, Vittel water, and this mineral water is to be used as percolation fluid or added to the percolation fluid. Thus, the percolation fluid can comprise or contain a bicarbonate mineral water rich in salts of manganese and/or of zinc.

The amount of catalytic mixture added to the percolation fluid can range for example from 0.01 to 1 wt.% relative to the weight of percolation fluid.

As stated above, when the catalytic mixture is not contained in the percolation liquid, it is added to the extract obtained after percolation, the amount being in the same range as stated above.

The method of the present invention can be carried out using a conventional device for generating a fluid under pressure, at a temperature preferably greater than or equal to 30°C, and more preferably ranging from 30°C to 150°C. Said device comprises a pressure-resistant chamber, equipped with a heating unit, as well as a circuit for conveying the fluid produced to the vegetable substance.

According to another embodiment, the device comprises a reservoir for liquid(s) and a pump for conveying the liquid or liquids to the chamber. The liquid contained in the reservoir is the percolation fluid as described above.

A device that is particularly useful for carrying out the method of the present invention is a coffee percolator of the "espresso" type. Such machines are well known in the industry. For example, these machines are described in documents AT-A- 168405, US-A-268891 1 , DE-A-32433870 and IT-A- 1265636, and in applications FR0650303, FR0650304, FR0650306, FR0650308.

According to a particular embodiment of the invention, the percolation stage is carried out with a fluid at a temperature above 30 °C, preferably between 30 °C and 150°C, under a pressure preferably of at least 3 bar, better still of at least 4 bar, more preferably of at least 10 bar. The pressure may range in particular from 3 to 30 bar, preferably from 4 to 30 bar, and quite particularly from 10 to 30 bar.

The vegetable substance or substances, in the form of solid or paste, can be used directly, in the device generating the fluid under pressure, in a container intended for this purpose. They can also be packaged in a special packaging device of the monodose type comprising a closed housing delimited by at least one wall that is at least partially permeable to a fluid under a pressure of at least 3 bar. Such devices are described, for example, in documents WO-A-00/56629, EP-A-512470, US-A-5897899 or WO-A-99/03753. These packaging devices are generally air-tight, moisture-proof and/or light-proof.

According to a particular embodiment, the housing is delimited by two sealed plates. According to another embodiment, the housing is delimited by a tray closed by a lid.

These devices can be made from woven or nonwoven materials, of plastics or vegetable matter, for example cellulose, of metal such as aluminium or a composite. Such devices are described for example in documents WO-A- 00/56629, EP-A-512470, US-A-5897899 or WO-A-99/03753. Catalytic mixture

In the catalytic mixture, according to a preferred embodiment of the invention, the proportions of the first constituent (i) and of the second constituent (ii) are such that:

[Mn(II)]

≤ 1 with [Mn(II)] ≠ 0

[HCO₃]

[Zn(II)]

< 1 with [Zn(II)] ≠ 0

[HCO₃] to [M°(g+ai(iD] _{≤ λ w}._{th [Mn(π)] and [zn(π)] ≠ o}

where [Mn(II)], [Zn(II)] and [HCO₃] represent, respectively, the molar concentrations of Mn(II), Zn(II) and HCO₃ in the mixture.

Generally, the ratio ^^Mn(π^ varies from 10^"5 to 10^"1, preferably from 10^"3 to 10^"2

[HCO₃] and is typically of the order of 5.10 -₃.

In the case of Zn(II), the ratio is generally from about 10 to 100 times

[HCO₃] greater than the ratio in the case of Mn(II).

Typically, said ratio is 10^"4 or more, preferably 10^"3 or more, and preferably of the order of 5.10^"1.

In the case of a mixture of Mn(II) and Zn(II), the ratio generally varies from 10^"5 to 10^"1, preferably 10^"3 to 10^"2, selecting a higher ratio when the proportion of Zn(II) in the mixture increases.

Generally, the molar concentration of Mn(II), Zn(II), or Mn(II) + Zn(II) in the final composition varies from 10^"3 to 10 mM/l, preferably from 10^"2 to 1 mM/l. When using only one or more salts or oxides of Mn(II), the molar concentration of Mn(II) in the final composition is typically from 10^"3 to 10^"1 mM/l, preferably 10^"2 to 10^"1 mM/l.

Preferably, when using only one or more salts or oxides of Zn(II), the concentration of Zn(II) in the final composition is from 5.10^"2 to 10 mM/l, preferably from 5.10^"1 to 1 mM/l.

Constituent (i) is selected from the salts and oxides of Mn(II) and/or of Zn(II) and mixtures thereof. Among the salts of Mn(II) and Zn(II) that are suitable for the present invention, we may mention the chloride, fluoride, iodide, sulphate, phosphate, nitrate and perchlorate, the salts of carboxylic acids and mixtures thereof.

As an example, we may mention manganese chloride, manganese carbonate (for example rhodochrosite), Mn(II) difluohde, Mn(II) acetate tetrahydrate, Mn(II) lactate thhydrate, Mn(II) phosphate, Mn(II) iodide, Mn(II) nitrate thhydrate, Mn(II) bromide and Mn(II) perchlorate tetrahydrate, Mn(II) sulphate monohydrate, zinc chloride, zinc sulphate.

Salts that are particularly preferred are MnCI₂ and ZnCI₂.

The second constituent is selected from the alkali-metal hydrogen carbonates, the alkaline-earth hydrogen carbonates and mixtures thereof. Among the alkali- metal and alkaline-earth hydrogen carbonates, we may mention the hydrogen carbonates of Na, K, Mg, Ca and mixtures thereof, preferably the hydrogen carbonate of Na.

As stated above, instead of using constituents (i) and (ii), it is also possible to use a natural water containing the two constituents, i.e. bicarbonate mineral waters rich in salts of manganese or of zinc, such as the Vichy waters (Lucas, Hόpital, Grande-Grille springs); from Roche Posay, Avene, or Vittel. This water can then be used as the percolation fluid or can be added to the percolation fluid. As stated above, the catalytic mixture can be put in the percolation fluid or added to the extract obtained after percolation.

In general, the amount of catalytic mixture can range for example from 0.01 to 1 wt.% relative to the weight of the extract obtained by the method of the invention.

Vegetable substance The vegetable extract can be prepared using any vegetable substance. The vegetable substance can be in the form of a solid or a paste, preferably in the form of a solid, and more preferably in the form of powder.

In the present invention, "solid form" means a compound or a composition in the form of a tablet, a film or a powder, a powder being a solid that is finely divided as particles, in contrast to a composition in the form of a cream or a gel, which are pliable compositions. In addition, "pulverulent" means a compound or a composition that is in the form of powder (comprising particles or grains).

"Paste form" in the sense of the present invention means a consistency intermediate between a solid phase and a liquid phase. The viscosity of this paste phase is preferably greater than 0.1 Pa.s, and more preferably greater than 1 Pa.s, measured at 25 °C with a shear rate of 10 s^"1.

The vegetable substances for use according to the invention can be obtained from wood, leaves, grasses, flowers, fruits, roots, bark or rind, pulp, peel, berries, beans and seeds of plants. They can be obtained for example from citrus fruits (lemon, orange, grapefruit), from other fruits (apple, kiwi, black currant, cherry), from [...] (green tea), from flowers (chamomile) and from any plant or any tree.

As examples of vegetable substances, we may notably mention: - for their emollient properties: apricot tree, cornflower, mullein, Roman chamomile, matricaha, corn poppy, fenugreek, marsh mallow, flax, lily, mallow, marigold, elder, lime, coltsfoot, psyllium, plantain, quince, peach tree, orange tree, cactus, apple tree;

- for their anti-inflammatory properties: agrimony, hawthorn, heather, couch grass, juniper, marshmallow, elder, lime, fenugreek, gentian, lettuce, wild pansy, plantain, bramble, rosemary, sage, black bryony, coltsfoot, everlasting, daisy;

- for their antipruritic properties: lady's mantle, lavender, walnut, plantain, scabious, cabbage, chervil, clematis, cucumber, comfrey, birthwort, burdock, mullein, Roman chamomile, eyebhght, climbing ivy;

- for their antiseptic properties: garlic, agrimony, bilberry, burdock, oak, comfrey, eucalyptus, juniper, rose geranium, laurel, lavender, marjoram, mint, pine, rosemary, sandalwood, wild thyme, thyme, sage, honeysuckle, everlasting, daisy, tansy;

- for their antisudohfic properties: sage, oak, walnut, pine, horsetail, coltsfoot;

- for their astringent properties: acacia, yarrow, agrimony, lady's mantle, arbutus, artemisia, comfrey, cypress, oak, dog rose, hamamelis, blackberry bush, bilberry, hazel, walnut, nettle, poplar, plantain, bramble, rhatany, rose bush, loosestrife, willow, tormentil, red vine, melilot;

- for their calmative properties: carrot, wild pansy, elder, lime, passionflower, basil, camphor, pear tree, apple tree, grapevine, lettuce, rose bush, ginger;

- for their healing properties:

St. John's wort, silverweed (Potentilla anserine), marigold, matricaha, Roman chamomile, comfrey, yarrow, wormwood, agrimony, artemisia, arnica, chervil, myrtle, periwinkle, plantain, poplar, primrose, sage, groundsel, elder, vervain (Verbena), angelica, birthwort, alder, aurone, bistort, birch, blessed thistle, juniper, medlar, eucalyptus, kidney vetch, bennet, centaury, cabbage, houseleek, strawberry, horsetail, meadowsweet, coltsfoot, wild pansy, burdock, daisy, lily;

- for their invigorating properties: St. John's wort, eglantine, mistletoe, mate, cassia tree, wormwood, arnica, calamint, cinnamon, geranium, hyssop, marjoram, balm, parsley, Scots pine, rosemary, savory, wild thyme, basil, dog rose, gentian, hop, white laurel, mint, sage, tormentil, yarrow, agrimony, bennet, bistort, oak, quince, cypress, horse- chestnut, medlar, walnut, nettle, plantain, water pear, cinquefoil, knotgrass (Polygonum), loosestrife, speedwell, angelica, artemisia, asperula, juniper, mustard, cinchona, fumitory, nasturtium, cress, kelp, butcher's-broom, tansy;

- for their properties promoting maintenance of the blood and lymphatic microcirculation: black currant, bilberry and grape seeds;

- for their textuhzing properties: wheat, fucus;

- for their antioxidant properties: rice, rosemary, sage, thyme, green tea, liquorice; - for their foaming or emulsifying properties:

Saponaria, ivy, butcher's-broom, Panama bark, Quillaja, sarsapahlla, quinoa, soya, citrus fruits such as lemon;

- for their photoprotective properties: aloe, sunflower, liquorice, magnolia, kaempeha; - for their thickening or absorbent properties: pea, wheat, potatoes, maize; and

- for their odorous properties: rosemary, violet, lavender, and rose.

More particularly, the vegetable substances used in the method according to the present invention are those containing polyphenols and oligomers of the flavonoid classes, such as:

- substances containing flavonols and oligomers which are present for example in lemon peel; liquorice roots; seeds of grapes and of blackcurrant; leaves of green teas, pine bark; hawthorn berries; cacao pods and beans;

- substances containing flavones, which are present for example in chamomile flowers and in skullcap root;

- substances containing flavanes, which are present for example in flower petals (cotton etc.); - substances containing isoflavones, which are present for example in soya bean sprouts;

- substances containing flavanones, which are present for example in pine bark, rind of citrus fruits (orange, lemon etc.) - substances containing chalcones, which are present for example in rind of citrus fruits and apple peel;

- substances containing arylchromanes, which are present for example in campeachy wood and brazilwood;

- substances containing anthocyanidines, which are present for example in sorghum seeds and leaves, and cacao pods and beans;

- substances containing coumahn derivatives, which are present for example in the bark of Skimmia japonica;

- and mixtures thereof.

The vegetable substances used according to the invention are preferably selected from the seeds of grapes and of black currant; the leaves of green teas, pine bark; hawthorn berries; cacao pods and beans; apple peel; campeachy wood; brazilwood; seeds and leaves of sorghum; and mixtures thereof.

The vegetable substance or substances can be used mixed with one or more solid or pasty, and preferably pulverulent, additives. On completion of percolation, these additives remain in the percolator. The additives can be selected from clays, salts, anionic, cationic, non-ionic, amphoteric, and zwittehonic surfactants, natural or synthetic thickeners, beads of glass, silica, nylon, waxes, pigments, alumina, titanium dioxide, zeolites, polymethylmethacrylate (PMMA), chitosan, maltodexthn, cyclodexthn, mono- or disaccharides such as glucose, sucrose, sorbitol, fructose, zinc oxide, zirconium oxide, particles of resin such as silicone or silicabades, talc, polyaspartic acid, borosilicates notably of calcium, polyethylene, cotton, polytetrafluoroethylene (PTFE), cellulose and its derivatives, superabsorbent compounds, carbonates of magnesium or of calcium, starch, optionally modified, maize seeds, gums of polydimethylsiloxane, polyacrylamide, porous hydroxyapatite, silk, collagen, sawdust, fucus powder, flours or extracts of wheat, of rice, of pea, of lupin, of soya, of barley, crosslinked polyvinylpyrrolidone, calcium alginate, activated charcoal, particles of poly(vinylidene chloride/acrylonitrile), notably those marketed under the general designation Expancel by the company AKZO NOBEL, and mixtures thereof.

When one or more additives are present, the vegetable substance or substances are preferably present in an amount ranging from 0.5 to 99 wt.%, better still from 1 to 80 wt.%, and even more preferably from 2 to 60 wt.% relative to the total weight of vegetable substance(s) and additives.

As stated above, the vegetable extract obtained by the method according to the invention can be used "as is" on keratinous materials and notably on the skin, to give an effect of looking well, or alternatively it can be incorporated in a composition containing a physiologically acceptable medium. The extract obtained or the composition containing it offers the advantage that they can be free from preservatives.

It is also possible to incorporate several extracts obtained by the method of the invention in a composition containing a physiologically acceptable medium.

The invention also relates to a vegetable extract obtained by the method of the invention, and a composition for topical, and notably cosmetic, application, containing an extract obtained by the method according to the invention.

The invention also relates to a method of cosmetic treatment of keratinous materials, characterized in that a vegetable extract is prepared according to the method defined above, and this extract is applied on the keratinous material.

The invention further relates to a method of cosmetic treatment of keratinous materials, characterized in that a vegetable extract is prepared according to the method defined above, it is added to a composition containing a physiologically acceptable medium, and this composition is applied on the keratinous material.

The keratinous material is preferably the skin. Application on the keratinous materials can be carried out for example by an operative or by means of a device not requiring human intervention. The application time can vary between 15 seconds and 1 hour.

When the extract is incorporated in a composition, the amount of vegetable extract(s) present in the composition can vary widely. It can range for example from 1.10^"3 to 99 wt.%, preferably from 1.10^'2 to 50 wt.%, and more preferably from 0.05 to 30 wt.% relative to the total weight of the composition.

In the composition containing a physiologically acceptable medium, the medium generally comprises water or a mixture of water and of at least one organic solvent for dissolving the compounds that would not be sufficiently soluble in water. As organic solvent, we may mention for example the CrC₄ lower alkanols, such as ethanol and isopropanol; polyols and polyol ethers such as 2- butoxyethanol, propylene glycol, monomethylether propylene glycol, monoethylether and monomethylether diethylene glycol, as well as aromatic alcohols such as benzyl alcohol or phenoxyethanol, and mixtures thereof.

The solvents are, preferably, present in proportions preferably between 1 and 40 wt.% relative to the total weight of the composition, and more preferably between 5 and 30 wt.%.

The physiologically acceptable medium can also contain one or more additives selected from those conventionally used in cosmetics. As examples of such additives, we may mention anionic, cationic, non-ionic, amphoteric, and zwittehonic surfactants or mixtures thereof, anionic, cationic, non-ionic, amphoteric, and zwittehonic polymers or mixtures thereof, mineral or organic thickeners, and in particular combination thickeners of anionic, cationic, non-ionic and amphoteric polymers, antioxidants, penetrants, sequestering agents, perfumes, buffers, dispersants, conditioners such as, for example, oils, film- forming agents, preservatives, opacifiers, as well as waxes, gums, coloured or nacreous pigments. The above additives are generally present in an amount that varies depending on the additive. Said amount can vary for example from 0.01 to 30 wt.% relative to the weight of the composition.

Of course, a person skilled in the art will be careful to select any such compound or compounds in such a way that the advantageous properties intrinsically associated with the cosmetic composition according to the invention are not, or substantially not, adversely affected by the addition or additions envisaged.

The pH of the composition is generally between 3 and 12, and preferably between 5 and 1 1. It can be adjusted to the desired value by means of acidifying or alkalizing agents usually used in cosmetics or alternatively using conventional buffering systems.

Among the acidifying agents, we may mention, as examples, the inorganic or organic acids such as hydrochloric acid, orthophosphoric acid, sulphuric acid, carboxylic acids such as acetic acid, tartaric acid, citric acid, lactic acid, sulphonic acids.

Among the alkalizing agents, we may mention, as examples, ammonia, alkaline carbonates, alkanolamines such as mono-, di- and triethanolamines as well as their derivatives, hydroxides of sodium or of potassium.

The composition can also contain one or more actives selected from those usually used in the field in question. As actives, we can notably use vitamins (vitamin A or retinol, vitamin C or ascorbic acid, vitamin E or tocopherol, vitamin K, vitamin PP or B3 or nicotinamide), alone or mixed together, as well as their derivatives and notably their esters; keratolytic and/or exfoliating agents such as β-hydroxyacids for example salicylic acid and its derivatives, α-hydroxyacids for example glycolic acid, lactic acid and citric acid, ascorbic acid and its derivatives; anti-inflammatory agents; soothing agents; hydrating agents; dulling agents; antiacne agents; and mixtures thereof.

The compositions in which the vegetable extract obtained according to the method of the invention can be incorporated can be in all the dosage forms conventionally used for topical application and notably in the form of aqueous or aqueous-alcoholic solutions, oil-in-water (O/W) or water-in-oil (W/O) or multiple (triple: W/O/W or 0/W/O) emulsions, aqueous gels, dehydrated anhydrous products, or dispersions of an oily phase in an aqueous phase using spherules, where said spherules can be polymeric nanoparticles such as nanospheres and nanocapsules, or lipid vesicles of the ionic type (liposomes) and/or non-ionic type. These compositions are prepared according to the usual methods. Moreover, they can be more or less fluid and can for example be in the form of a white or coloured cream, a milk, a lotion, a serum, a film or a powder.

Depending on the desired dosage form, any compound usually required for obtaining the desired dosage form can be added to the composition; for example, if we wish to have an emulsion, fats are added, for example oils, and optionally emulsifying agents.

The extract obtained by the method of the invention or the composition containing it can constitute a product for care of the skin, having a nourishing, moisturizing, anti-wrinkle, or anti-drying effect, or any other application for care of the skin (for example an effect of looking well), or a make-up product such as a foundation for colouring the skin and/or protecting it while providing care.

The invention also relates to a kit for carrying out the method as defined above, comprising one or more containers notably in the form of a sachet or of a capsule, suitable for percolation under pressure by fluid means, the container or containers delimiting at least one housing containing at least one vegetable substance in the form of solid or paste, one or more containers containing a catalytic mixture comprising (i) a first constituent selected from the salts and oxides of Mn(II) and/or of Zn(II) and mixtures thereof, and (ii) a second constituent selected from the alkali-metal hydrogen carbonates, the alkaline- earth hydrogen carbonates and mixtures thereof, and optionally one or more containers containing a physiologically acceptable medium. This kit makes it possible to obtain a composition according to the invention, where the catalytic mixture is added to the percolation fluid or it is added to the percolation extract, the mixture obtained being optionally added to a physiologically acceptable medium which can be an emulsion, a dry carrier or any other cosmetic dosage form as described above.

The examples given below are intended to illustrate the present invention.

Example 1 :

Put 2 g of cacao pods in a capsule, and put the capsule in a commercially available espresso machine. The steam produced by the machine is then passed through this pulverulent mixture until a composition (A) is obtained, having a final volume of 20 ml. The extract is collected in a solution containing sodium bicarbonate at a concentration of 1 mM/l (millimoles per litre) and manganese chloride at a concentration of 5 mM/l.

We thus obtain a self-tanning composition that is ready to be applied to the skin.

Example 2:

Using the same procedure as in example 1 , steam from Vichy water is passed through 5 g of powdered sorghum seeds, which are in the container that is provided for receiving a solid compound, until an extract is obtained with a volume of 10 ml. The aqueous extract obtained is collected in a beaker that can contain 10O g of the dry carrier stated below, which dissolves on contact. We thus obtain a self-tanning composition that is ready to be applied to the skin.

Dry carrier:

- Modified starch (C^* Flo 06205) 39.5 %

- Silicone oil (phenyl thmethicone sold under the name

DC 556 Fluid by Dow Corning) 60 %

- Sodium bicarbonate 0.5 %

Claims

1. Method of preparation of a vegetable extract, characterized in that it comprises (1 ) a stage of percolation of fluid under pressure through at least one vegetable substance in the form of solid or paste, and (2) the use of a catalytic mixture comprising (i) a first constituent selected from the salts and oxides of Mn(II) and/or of Zn(II) and mixtures thereof, and (ii) a second constituent selected from the alkali-metal hydrogen carbonates, the alkaline-earth hydrogen carbonates and mixtures thereof, the catalytic mixture being either contained in the percolation fluid or added to the extract obtained after the percolation stage.

2. Method according to Claim 1 , characterized in that the pressure is at least 3 bar and preferably at least 4 bar.

3. Method according to Claim 1 or 2, characterized in that the fluid comprises steam optionally accompanied by liquid water, or by one or more physiologically acceptable liquid and/or gaseous solvents, or by a mixture of steam optionally accompanied by liquid water, and one or more physiologically acceptable liquid and/or gaseous solvents.

4. Method according to any one of the preceding claims, characterized in that the catalytic mixture comprises or contains a bicarbonate mineral water rich in salts of manganese and/or of zinc.

5. Method according to any one of the preceding claims, characterized in that in the catalytic mixture, the proportions of the first constituent (i) and of the second constituent (ii) are such that:

^™ < 1 with [Mn(II)] _≠ 0

[HCO₃]

^™ < 1 with [Zn(II)] ≠ 0

[HCO₃] ^{[Mn(II) + Zn(II)]} < 1 with [Mn(II)] and [Zn(II)] ≠ 0 [HCO3]

6. Method according to any one of the preceding claims, characterized in that in the catalytic mixture, the second constituent is selected from the alkali-metal hydrogen carbonates, the alkaline-earth hydrogen carbonates and mixtures thereof.

7. Method according to any one of the preceding claims, characterized in that the catalytic mixture is present in an amount from 0.01 to 1 wt.% relative to the total weight of the percolation fluid.

8. Method according to any one of the preceding claims, characterized in that the percolation fluid contains the catalytic mixture.

9. Method according to any one of the preceding claims, characterized in that the vegetable substance is selected from:

- substances containing flavonols and flavonol oligomers,

- substances containing flavones,

- substances containing flavanes,

- substances containing isoflavones, - substances containing flavanones,

- substances containing chalcones,

- substances containing arylchromanes,

- substances containing anthocyanidines,

- substances containing coumarin derivatives; - and mixtures thereof.

10. Method according to any one of the preceding claims, characterized in that the vegetable substance is selected from lemon peel; liquorice roots; seeds of grapes and of blackcurrant; leaves of green teas, pine bark; hawthorn berries; cacao pods and beans; chamomile flowers; skullcap root; flower petals; soya bean sprouts; pine bark, peel of citrus fruits; peel of citrus fruits and apple peel; campeachy wood; brazilwood; sorghum seeds and leaves, cacao pods and beans; bark of Skimmia japonica.

11. Method according to any one of the preceding claims, characterized in that the vegetable substance is used mixed with one or more additives in solid or paste form.

12. Method according to the preceding claim, characterized in that the additive is selected from clays, salts, anionic, non-ionic, cationic or zwitterionic surfactants, natural or synthetic thickeners, starch, optionally modified, beads of glass, silica, nylon, alumina, titanium dioxide, zeolites, poly(methyl methacrylate), chitosan, maltodexthn, cyclodextrin, mono or disacchahdes, zinc oxide, zirconium oxide, particles of resin, talc, polyaspartic acid, borosilicates, polyethylene, cotton, polytetrafluoroethylene, cellulose and its derivatives, superabsorbent compounds, carbonates of magnesium or of calcium, maize seeds, gums of polydimethylsiloxane, polyacrylamide, porous hydroxyapatite, silk, collagen, sawdust, fucus powder, flours or extracts of wheat, of rice, of pea, of lupin, of soya, of barley, crosslinked polyvinylpyrrolidone, calcium alginate, activated charcoal, and particles of poly(vinylidene chloride/acrylonitrile).

13. Vegetable extract obtained by the method according to any one of the preceding claims.

14. Composition for topical application, containing the vegetable extract obtained by the method according to any one of the preceding claims.

15. Composition according to the preceding claim, characterized in that it is preservative-free.

16. Cosmetic use of the extract obtained by the method according to any one of Claims 1 to 12, for the cosmetic treatment of keratinous materials.

17. Cosmetic use of the extract obtained by the method according to any one of Claims 1 to 12, as a self-tanning product or in a self-tanning composition.

18. Cosmetic use of the extract obtained by the method according to any one of Claims 1 to 12, for imparting a coloration or a tan to the skin.

19. Method of cosmetic treatment of keratinous materials, characterized in that an extract is prepared by the method according to any one of Claims 1 to 12, and this extract is applied to the keratinous material.

20. Method of cosmetic treatment of keratinous materials, characterized in that an extract is prepared by the method according to any one of Claims 1 to 12, it is added to a composition containing a physiologically acceptable medium, and this composition is applied to the keratinous material.

21. Method according to Claim 19 or 20, characterized in that the keratinous material is the skin.

22. Cosmetic kit for carrying out the method according to any one of Claims 1 to 12, comprising (1 ) one or more containers suitable for percolation under pressure by fluid means, the container or containers delimiting at least one housing containing at least one vegetable substance in the form of solid or paste, (2) one or more containers containing a catalytic mixture comprising (i) a first constituent selected from the salts and oxides of Mn(II) and/or of Zn(II) and mixtures thereof, and (ii) a second constituent selected from the alkali-metal hydrogen carbonates, the alkaline-earth hydrogen carbonates and mixtures thereof, and (3) optionally one or more containers containing a physiologically acceptable medium.