A method based on amino acids for the prevention and/or dermatologic and/or cosmetic treatment of the skin disorders and of the related cutaneou-s structures, in particular nails and hair, for use in applications for moisturising, accelerating wound healing times, anti-age efficiency, antibacterial action, lightening/illuminating action, treating herpes and psoriasis, antioxidant and detoxifying action, barrier effect. In such method, an amino acid and/or a derivative and/or a mixture is carried in a hydrophobic medium to improve efficiency, stability and tolerabilxty of the product.

PRIOR ART

Amino acids are essential compounds for the metabolism of the skin and important components of the natural moisturising factor (NMF) in the horny layer.

The latter is a mixture that serves to maintain the correct amount of humidity, preventing excess demoisturising of the keratin lamellae. In this way, it allows keeping the surface of the skin whole, elastic and flexible.

NMF is formed by various substances and it is generated, besides keratin, by the cell breakage. Actually, when the cells of the skin die and form the horny layer, the proteins present therein are degraded into, amino acids which constitute almost half of the NMF.

This mixture, fundamental for maintaining a correct equilibrium in the skin, has the disadvantage of being water soluble, hence it is easily eliminated by water and detergents during washing.

An important objective of modern functional cosmetics is that of reconstructing this natural layer of moisturizing substance on the skin surface. The use of amino acids in the field of dermatology and cosmetics has been known over time. Actually, these molecules have emollient, cicatrizing and restitutive properties and they are used in creams and lotions with moisturising, anti-wrinkles action etc.

It is known that each amino acid has specific properties and performs particular actions on the skin.

Some of the main actions of the amino acids ^' which have the effect of protecting and keeping the skin healthy are indicated below by way of example:

- L-Lysine: conditioning agent for the skin and for repairing tissues, in that required for the formation of collagen. It confers the skin a smooth velvety effect. It is efficient at reducing symptoms caused by Herpes Simplex infection

- L-Histidine: it has antioxidant properties and protects the skin against the harmful effects of UV radiations

- L-Arginine: it accelerates the wound healing times

- L-aspartic acid: involved in the formation of DNA

L-Threonine: important for the formation of collagen and elastin

- L-Serine: involved in the formation of cellular membranes

- L-Proline: important for keeping the structures of the skin healthy and functional

- L-Glycine: crucial for repairing tissue damages, it enhances wound healing

- L-Alanine : involved in protein synthesis

- L-Methionine : it has antioxidant and detoxifying properties

L-Isoleucine : a branched chain amino acid, it plays an important role in protein synthesis and in tissue repair - L-Cysteine: it is one of the main amino acids of keratin, to which it confers stability and resistance due to the formation of disulfide bonds. It contributes to reinforcing and keeping the structures of the skin and the related cutaneous structures (nails and hair) functional

- L-Leucine: a branched chain amino acid, serves a protection, action against protein degradation

- L-Tyrosine: a fundamental protein constituent, it helps the penetration of moisturising agents into the skin. Furthermore, it is converted by the cells of the skin into melanin, which protects against the harmful effects of UV radiations. It can be used as L-Acetyl-tyrosine, the corresponding bioavailable form

- L-Phenylalanine : an amino acid present in numerous proteins, it can be converted into L-Tyrosine

- Taurine: it is a natural aminosulfonic acid which stimulates the synthesis of all the three classes of barrier lipids (ceramides, cholesterol, fatty acids) in the skin. Furthermore, it accelerates reparation of skin damages caused by heat stimuli or UV radiations.

Due to the properties thereof, the amino acids are widely used in the cosmetic industry for preparing formulations for maintaining a healthy skin and for the prevention and treatment of imperfections or mild disorders. Given that amino acids are water soluble molecules, the commercial products containing them are generally emulsions (creams, lotions , etc . ) .

Emulsions are oil dispersions in water or vice versa and thus subject of instability. Furthermore, given that they contain water, they create problems related to risks of contamination and thus they require addition of emulsifiers, stabilisers and preservatives which complicate the formulation of the product, increase the number of ingredients, the costs, the risk of intolerance, allergies and toxicity.

The object of the present invention is to provide a rational solution to the problem through vehicles with extremely low water content and where solubilisation of amino acids in a hydrophobic medium is obtained through fat-soluble chelating agents .

DESCRIPTION OF THE INVENTION

The present invention regards a cosmetic formulation for topical use containing at least one amino acid in a mainly hydrophobic vehicle for the treatment of skin ^' and the related cutaneous structures, in particular nails and hair, as a novel approach for solving numerous dermatologic and/or cosmetic problems.

In particular, the subject of the invention is a composition for dermatologic and/or cosmetic use as a hydrophobic gel, oleolite or butter comprising at least one amino acid; at least one hydrophobic vehicle such as oil, silicone or butter; a porous polymer and/or a "spider ester" and/or micro-and nano-particle carriers and vesicular carriers; molecular inclusion systems; thickeners and stabilisers of the hydrophobic phase; hydrogenated oils, silicone and non-silicon waxes such as bee wax; hydrophobic silicas. The amount of amino acids used may widely vary from 0.01% to 30%, preferably from 0.05% to 10%, even more preferably from 0.1% to 5% of the total weight of the cosmetic formulation. The amino acids, alone or combined, are selected from among L-alanine, L-aspartic acid, L-glutaminic acid, L-glycine, L-proline, L-serine, L-tyrosine, L- cysteine, L-arginine, L-histidine, L-leucine, L- isoleucine, L-lysine, L-methionine, L-phenylalanine, L-threonine, L-tryptophan, L-valine, L-asparagine, L-glutamine, L-acetyl-tyrosine, taurine. The hydrophobic composition constituting the vehicle for the amino acids comprises, in weight/weight percentage on the total weight of the formulation, from 70% to 90% of suitable oil, butter or silicone vehicle for cosmetic use; such as: vegetable oils like squalene, argania spinosa, adansonia digitata; synthetic oils such as decyl oleate, caprylic capric triglyceride .

The silicon medium is preferably selected from among the group including pentamer cyclomethicone, tetramer cyclomethicone, hexamer cyclomethicone, dimethicone, phenyl trimethicone, diphenyl trimethicone, polysilicone-11, hexamethyldisiloxane, disiloxane, dimethicone/vinyl dimethicone crosspolymer , dimethicone crosspolymer or a mixture thereof .

The formulation, according to the present invention, may also include another oil component at a percentage comprised between 5% and 20% selected from among vegetable oils and esters of fatty acids, such as for example octyl palmitate, isopropyl myristate, ethyl oleate, ethers, fatty alcohols, unsaponifiables, such as those derived from olive, avocado, soy oil or a mixture thereof.

Regardless of the mainly hydrophobic characteristic of the formulation, the composition may contain small percentages of water (not exceeding 10%) in association to a porous polymer, such as methylmetacrilate crosspolymer , in a polymer/water ratio comprised between 4:6 and 7:3. Said polymer facilitates the solubilisation of the active components in the formulation increasing stability thereof and simultaneously contributes to improve the likability of the preparation.

Alternatively or in association with the above- mentioned porous polymer, "spider esters" (U.S. Pat. No. 7,437,707), such as for example sorbeth-2 hexaoleate, glycereth-6-tricocoate, can be used. Due to their distinctive chemical structure, such molecules are capable of binding hydrophilic molecules and allowing solubilisation thereof in hydrophobic media, considerably limiting the amount of water present in the formulation (not exceeding 2%) . "Spider esters" are capable of increasing the stability of the product sequestering and protecting it against degradation. Once at contact with the skin, the "spider esters" release the active compound and facilitate penetration thereof into the surface layers of the epidermis with an ensuing increase of efficiency. Either microspheres or cyclodextrins can be used alternatively or in association therewith also with the aim of increasing stability, facilitating a slow release and increasing efficiency.

With the aim of improving the stability of the hydrophobic formula, such as for example a hydrophobic gel, the formulation may include- aluminium/magnesium hydroxide stearate, or hydrophobic silicas such as silica dimethyl silylate, or polyethylene and derivatives or hydrogenated oils, such as castor oil or rheocin, or natural waxes such as bee wax, minerals such as ozokerite, and synthetic waxes such as silicone waxes. An example consists in hydrogenated castor oil or rheocin at percentage, with respect to the total weight of the composition, comprised between 1% and 5%.

The incorporation of the amino acids, substances soluble in water, in an anhydrous vehicle offers interesting advantages with respect to the conventional formulations (emulsions) .

Firstly, the hydrophobic gel subject of the present invention contains a limited number of ingredients, such characteristic being particularly desired, given that the lower the number of- components inserted in the cosmetic formulation the lower is the risk of developing sensitivity or allergy phenomena due to single allergens.

Furthermore, the hydrophobic vehicle described by the present invention is characterized by low water content. This offers the important advantage of increasing the stability of the composition with a lower risk of microbial contamination. In particular, the innovative combination of ingredients used in the present formulation is characterized by a surprising microbiological stability which thus allows eliminating preservatives entirely. It is actually known that preservatives used in the dermatology and/or cosmetic field are among the greatest sensitising agents present in products for topic use, responsible for unwanted adverse reaction, including contact dermatitis, urticaria, photosensitisation. Elimination of preservatives from the formulation allows safely extending the use even to sensitive and allergic subjects or subjects with sensitive skin.

The hydrophobic form whose example is a hydrophobic gel, offers the further advantage of making the product adapted to a packaging ^' incompatible with water, such as for example the use of capsules made of plant or animal gelatine in single dose of like softgel. Furthermore, such formulation has distinctive characteristics of cosmetic likability, due to a silky and velvety texture and an excellent spreadability and flowability on the skin. These characteristics allow the product to be easily applied on the skin, where it forms a thin and homogeneous film which facilitates the penetration of the active ingredients.

The cosmetic composition subject of the invention is characterised by an ideal stability over time both from a microbiological evaluation and from a viscosity and rheological properties point of view. The formulation for topical use described in the present invention is indicated for use in methods for the treatment of the skin and the related cutaneous structures (nails and hair) in wide range of methods, comprising as a result for example moisturising, accelerations of wound healing times, anti-ageing effect (by promoting the synthesis of collagen and inhibition of collagenase which determines an increase of the collagen of type I) , antibacterial action, lightening/illuminating action, dermatological and/or cosmetic treatment of herpes and psoriasis, antioxidant and detoxifying action, barrier effect.

EXAMPLES

With the aim of further illustrating the present invention, following are two general examples, non- limiting of the present invention, describing a possible method for providing a hydrophobic form based on amino acids, such as a hydrophobic gel, according to what has been described up to now:

Example 1

Ingredients % weight

Cyclomethicone 51

Dimethicone Crosspolymer 35

Amino acid (or combination of several 2 amino acids)

Methylmethacrilate Crosspolymer 5

Water 5

Rheocin 2

Amino acids, or a mixture thereof, and water are mixed together up to obtaining a limpid solution. The methylmethacrilate crosspolymer is added thereto, stirring using a helical stirrer (400 rpm for 30 minutes) . Upon obtaining a homogeneous paste, cyclomethicone is added continuing to stir for another 30 minutes, after which dimethicone crosspolymer and rheocin are added to the compound continuing stirring up to obtaining a homogeneous gel .

Example 2

Ingredients % weight

Cyclomethicone 46

Dimethicone Crosspolymer 30

Amino acid (or combination of several 0.1 amino acids)

Sorbeth-2 hexaoleate 20

Water 2

Rheocin 1.9

Amino acids, or a mixture thereof, and water are mixed together up to obtaining a limpid solution. After being heated to 60°, sorbeth-2 hexaoleate is added thereto. The compound is stirred using a helical stirrer for 30 minutes, after which, still stirring, first cyclomethicone and at the end dimethicone crosspolymer and rheocin are added, up to obtaining a homogeneous gel. As observable from the above-indicated non-limiting examples, the application of this method allows considerably simplifying the formula reducing the costs of preparation as well as the number of ingredients.