The invention relates to the use of an a-hydroxy acid in combination with a titanium oxide in or for the preparation of a cosmetic or dennatological composition applied topically to the skin of the face and/or body with the object of lightening the skin. These compositions can be care or make-up products.
It is common for people having a coloured or even a dark skin to wish to lighten the skin, and to use cosmetic or dennatological compositions containing lightening agents for this purpose.
The substances most widely used as lightening agents are hydroquinone and its derivatives, especially its ethers such as hydroquinone monomethyl ether and monoethyl ether, and most of all kojic acid and its derivatives.
Hydroquinone and its derivatives, while being undoubtedly effective, are unfortunately not without side effects as a result of their toxicity, which can make them awkward or even dangerous to use. Thus, hydroquinone, the use of which is, moreover, limited by law to a concentration of 2%, is an especially irritant and cytotoxic compound for melanocytes, and its total or partial replacement has been envisaged by many authors.
Hydroquinone may be used in combination with hydroxy acids. Thus, EP-A-273,202 describes the improvement of the efficacy of a topical active agent by the addition of an effective amount of a hydroxy acid. Hydroquinone is mentioned as an active agent for treating age spots. However, the combination has the drawbacks associated with the use of hydroquinone.
Moreover, kojic acid and its derivatives have the drawback of being expensive and of not being able, for this reason, to be used in a high concentration in products "for mass consumption", that is to say available to everyone.
Other lightening agents are known. Thus,
US-A-5,262,153 teaches the use of lactic acid and its salts for lightening the skin. However, the lightening effect
obtained is considered to be insufficient.
There hence remains the need for an effective lightening agent which is not toxic and which is reasonably priced, enabling effective lightening compositions "for mass consumption" to be obtained.
Thus, the present invention provides the use in combination of at least one α-hydroxy acid and at least one titanium oxide, in and/or for the preparation of a cosmetic composition, as an agent for lightening the skin.
The present invention also provides the use in combination of at least one α-hydroxy acid and at least one titanium oxide, in the preparation of a dermatological composition, as an agent for lightening the skin.
The present invention further provides a cosmetic process for lightening the skin which comprises applying to the skin a composition containing, in combination, at least one α-hydroxy acid and at least one titanium oxide as sole agent for lightening the skin.
The combination consists of inexpensive common products leading to a lightening composition that can be afforded by everyone. In addition, the Applicant has found that the claimed combination has a definite and surprising lightening power, similar to the effect obtainable with more expensive products such as kojic acid.
It is known from JP-A-57-123824 to use titanium dioxide to lighten the skin, but this document neither discloses nor suggests combining it with an α-hydroxy acid with a view to providing an effective lightening composition at reasonable cost.
CH-A-684739 describes a lightening composition for the skin, comprising a flavonoid and ascorbic acid. In an example, the composition also contains titanium dioxide and glycolic acid, but this document does not teach that titanium dioxide and glycolic acid may be used as a lightening agent.
The α-hydroxy acids may, for example, be saturated or unsaturated, linear, branched or cyclic. The hydrogen atoms of the carbon chain may, in addition, be replaced by halogens (i.e. may be halogenated), alkyl, acyl, acyloxy, alkoxycarbonyl or alkoxy radicals having from 2 to 28 carbon
atoms.
The α-hydroxy acid which can be used according to the invention can consist of a mono- or polycarboxylic acid containing one or more hydroxyl functions, it being necessary for at least one of these hydroxyl functions to occupy an a position to the acid group.
Preferably, the α-hydroxy acids used in the
invention are α-hydroxyalkanoic acids, especially having from 2 to 18 carbon atoms.
As α-hydroxy acids which can be used in the
invention, there may be mentioned, in particular, glycolic (or α-hydroxyethanoic), lactic (or α-hydroxypropanoic), malic (or hydroxybutanedioic), tartaric (or dihydroxybutanedioic), citric, mandelic, α-hydroxycaprylic (or α-hydroxyoctanoic) , α-hydroxyhexanoic, α-hydroxydecanoic, α-hydroxydodecanoic, α-hydroxytetradecanoic, α-hydroxyhexadecanoic, α-hydroxyoctadecanoic, α-hydroxyeicosanoic, α-hydroxydocosanoic, α-hydroxyhexacosanoic and α-hydroxyoctacosanoic acids.
It is preferable to use, according to the invention, lactic acid, glycolic acid, citric acid and/or tartaric acid.
These acids may occur in the composition in free acid form and/or in the form of one of their associated salts, or alternatively in the form of one of their esters or their corresponding amides or, as a further possibility, where appropriate, in the form of the corresponding lactide (form obtained by self-esterification of the molecules).
The salts may be prepared by known processes, for example by neutralization of an α-hydroxy acid with a suitable base such as sodium, potassium or ammonium hydroxides, or an organic base such as triethanolamine or amino acids (e.g. lysine, arginine).
When an α-hydroxy acid ester is used, it can be, in particular, a methyl, ethyl, propyl, butyl, pentyl, hexyl or octyl ester.
To obtain a satisfactory lightening effect, the composition according to the invention preferably has a final pH of 2.5 to 6.
The α-hydroxy acids are preferably used, according
to the present invention, in an amount of from 0.01 to 50% by weight, still more preferably from 0.5 to 20 %, and better still from 2 to 10 %.
As the titanium oxide used according to the
invention, it is possible to use, in particular, a titanium dioxide, as it is or optionally surface-treated, taking the form of pigments or of nanopigments. In the form of nanopigments, the average sizes of the particles are, for example, from 5 to 100 run.
The untreated titanium oxides can be, for example, those sold by the company Tayca under the trade names "Microtitanium Dioxide MT 500 B" or "Microtitanium Dioxide MT 600 B", or those sold by the company Tioxide under the trade name "Selected Tioxide A-HRC".
The surface-treated titanium oxides can be, for example, the oxides treated with:
- silica and alumina, such as the products "Microtitanium
Dioxide MT 500 SA" and "Microtitanium Dioxide MT 100 SA" from
the company Tayca, and the products "Tioveil Fin", "Tioveil
OP", "Tioveil MOTG" and "Tioveil IPM" from the company
Tioxide,
- alumina and aluminium stearate, such as the product
"Microtitanium Dioxide MT 100 T" from the company Tayca,
- alumina and aluminium laurate, such as the product
"Microtitanium Dioxide MT 100 S" from the company Tayca,
- iron oxides and iron stearate, such as the product
"Microtitanium Dioxide MT 100 F" from the company Tayca,
- silica, alumina and silicone, such as the products
"Microtitanium Dioxide MT 100 SAS", "Microtitanium Dioxide
MT 600 SAS" and "Microtitanium Dioxide MT 500 SAS" from the
company Tayca,
- sodium hexametaphosphate, such as the product
"Microtitanium Dioxide MT 150 W" from the company Tayca,
- octyltrimethoxysilane, such as the product "T-805" from the
company Degussa,
- alumina and stearic acid, such as the product "UVT-M160"
from the company Kemira,
- alumina and glycerol, such as the product "UVT-M212" from
the company Kemira, or
- alumina and silicone, such as the product "UVT-M262" from the company Kemira.
The titanium oxides may be also used as pigmentary pastes, i.e. in a pastry mixture containig pigments and a binder such as oil(s) with a dispersing agent. The use of pigmentary pastes allows the introduction with ease of a greater amount of pigment.
The titanium oxides are preferably used, according to the present invention, in an amount of from 0.05 to 20% by weight, still more preferably from 0.5 to 10%.
The application of a composition containing the above combination enables a distinct lightening of the skin to be obtained.
In the cosmetic process of the invention the
α-hydroxy acid and the titanium oxide are used in effective amounts so as to see a visible lightening of the skin as soon as the composition has been applied. The compositions according to the invention are especially adapted for non-Caucasian skins such as black skins, asian skins or oriental skins.
The compositions may be presented in all the application formulations normally used for a topical application, for example in the form of solutions, gels, dispersions of the lotion or serum type, emulsions of liquid or semi-liquid consistency of the milk type, obtained by dispersing a fatty phase in an aqueous phase (O/W) or vice versa (W/O), or suspensions or emulsions of soft, semi-solid or solid consistency of the cream or gel type, or alternatively of microemulsions, microcapsules, microparticles or vesicular dispersions of the ionic and/or nonionic type. These compositions are prepared according to standard methods.
In a known manner, the cosmetic or dermatological compositions may contain adjuvants which are customary in the cosmetic or dermatological field, such as emulsifiers, hydrophilic or lipophilic gelling agents, hydrophilic or lipophilic active agents other than the titanium oxide and the α-hydroxy acid, preservatives, antioxidants, perfumes, fillers, screening agents and colourants. The amounts of
these different adjuvants are those traditionally used in the cosmetic and/or dermatological fields. They may, for example, be from 0.01 % to 20 % of the total weight of the composition. These adjuvants, depending on their nature, may be introduced into the fatty phase, into the aqueous phase and/or into the lipid vesicles.
As emulsifiers, water-in-oil (W/O) or oil-in-water (O/W) emulsifiers may be used, depending on the final emulsion desired.
As emulsifiers, there may be mentioned, for example, a glyceryl stearate/PEG-100 stearate mixture (Arlacel 165 sold by the company ICI), PEG-20 stearate (Myrj 49 sold by the company ICI), PEG-40 stearate (Myrj 52 sold by the company ICI) and sorbitan tristearate (Span 65 sold by the company ICI).
The emulsifier content can, for example, be from 0.1 % to 15 % by weight, preferably from 0.5 % to 5 % by weight, relative to the total weight of the composition.
Coemulsifiers may be added to the composition
according to the invention, for example in an amount of from 0.05 % to 10 % by weight relative to the total weight of the composition. Glyceryl stearate may be mentioned as a coemulsifier.
In the dispersions of lipid vesicles, the emulsifier can consist of the vesicles themselves or of ionic and/or nonionic lipids.
As oils which can be used, mineral oils, vegetables oils (maize-germ oil), synthetic oils (isohexadecane), silicone oils (cyclomethicone) and fluorinated oils may be mentioned. It is also possible to use fatty alcohols (stearyl alcohol, cetyl alcohol), fatty acids (stearic acid) and waxes.
As hydrophilic active agents, it is possible to use, for example, proteins or protein hydrolysates, amino acids, polyols, especially glycerol or sorbitol, urea, allantoin, sugars and their derivatives and glycyrrhetinic acid.
As lipophilic active agents, tocopherol (vitamin E) and its derivatives, essential fatty acids, ceramides and essential oils may be mentioned.
It is also possible to use UV screening agents having a lipophilic or hydrophilic property and zinc oxides in these compositions.
These compositions constitute, in particular, treatment or care creams for the face, hands or body, body milks for protection or care, and lotions, gels or mousses for the care or treatment of the skin.
The following Examples further illustrate the invention. In these Examples, the proportions shown are percentages by weight.
Example 1; O/W emulsion: lightening cream for the face Oily phase Al:
Arlacel 165 1.2 %
Myrj 49 1.2 %
Maize-germ oil 5 %
Cyclomethicone 10 %
Stearic acid 0.6 %
Stearyl alcohol 0.6 %
Cetyl alcohol 0.6%
Preservatives 0.3 %
Oily phase A2:
Isohexadecane 5 %
Titanium dioxide (selected Tioxide A-HRC) 5 %
Aqueous phase:
Glycolic acid 3 %
Sodium hydroxide qs pH 3.8
Glycerol 3 %
Water qs 100 %
Procedure: the oily phase Al is heated to 80°C. Separately, the oily phase A2 is prepared by dispersing the titanium oxide in the isohexadecane. The phases Al and A2 are then mixed and poured into the aqueous phase with stirring. The resulting mixture is cooled while stirring is maintained.
A white cream having a lightening property is obtained.
Example 2; O/W emulsion: lightening cream for the face
Example 2 is identical to Example 1, except for the fact that the composition contains surface-treated titanium dioxide (Microtitanium Dioxide MT 100 T from Tayca) as the titanium dioxide.
Example 3; O/W emulsion: lightening cream for the hands and
body
Oily phase Al:
Cetyl alcohol 0.6 %
Span 65 1.9 %
Myrj 52 0.85 %
Glyceryl stearate 2 %
Cyclomethicone 8 %
Tocopherol acetate 0.5 %
Oily phase A2:
Isohexadecane 5 %
Titanium dioxide (selected Tioxide A-HRC
from Tioxide) 5 %
Aqueous phase:
Glycolic acid 2.9 %
Citric acid 0.9 %
Lactic acid 3.1 %
Tartaric acid 0.1 %
Sodium hydroxide qs pH 3
Glycerol 4 %
Preservatives 0.3 %
Water qs 100 %
The procedure is the same as for Example 1. A cream is obtained, the application of which enables a good lightening effect to be obtained.

We Claim
1. Use in combination of at least one α-hydroxy
acid and at least one titanium oxide, in and/or for the
preparation of a cosmetic composition, as an agent for
lightening the skin.
2. Use in combination of at least one α-hydroxy
acid and at least one titanium oxide, in the preparation of a
dermatological composition, as an agent for lightening the
skin.
3. Use according to claim 1 or 2, wherein the
α-hydroxy acid is an α-hydroxyalkanoic acid.
4. Use according to any one of the preceding
claims wherein the α-hydroxy acid is glycolic, lactic, malic, tartaric, citric, mandelic, α-hydroxycaprylic, α-hydroxyhexanoic, α-hydroxydecanoic, α-hydroxydodecanoic, α-hydroxytetradecanoic, α-hydroxyhexadecanoic, α-hydroxyoctadecanoic, α-hydroxyeicosanoic, α-hydroxydocosanoic, α-hydroxyhexacosanoic or α-hydroxyoctacosanoic acid.
5. Use according to any one of the preceding
claims wherein the titanium oxide is a titanium dioxide.
6. Use according to claim 5 wherein the titanium
dioxide has been surface-treated.
7. Use according to any one of the preceding
claims wherein the α-hydroxy acid is present in a
concentration of from 0.01 to 50 % by weight relative to the
total weight of the composition.
8. Use according to claim 7 wherein the α-hydroxy
acid is present in a concentration of from 0.5 to 20 % by
weight relative to the total weight of the composition.
9. Use according to any one of the preceding
claims wherein the titanium oxide is present in a
concentration of from 0.05 to 20 % by weight relative to the
total weight of the composition.
10. Use according to claim 9 wherein the titanium
oxide is present in a concentration of from 0.5 to 10 % by
weight relative to the total weight of the composition.
11. Use according to any one of the preceding
claims wherein the composition has a final pH of 2.5 to 6.
12. Use according to any one of the preceding
claims wherein the composition is a water-in-oil emulsion, an oil-in-water emulsion, a microemulsion, a serum or a dispersion of vesicles.
13. A cosmetic process for lightening the skin
which comprises applying to the skin a composition
containing, in combination, at least one α-hydroxy acid and
at least one titanium oxide as sole agent for lightening the
skin.
14. A process according to claim 13 wherein the
composition is applied on non-Caucasian skin.
15. A process according to claim 13 or 14 wherein
the α-hydroxy acid is an α-hydroxyalkanoic acid.
16. A process according to any one of claims 13 to
15 wherein the α-hydroxy acid is glycolic, lactic, malic,
tartaric, citric, mandelic, α-hydroxycaprylic,
α-hydroxyhexanoic, α-hydroxydecanoic, α-hydroxydodecanoic,
α-hydroxytetradecanoic, α-hydroxyhexadecanoic,
α-hydroxyoctadecanoic, α-hydroxyeicosanoic,
α-hydroxydocosanoic, α-hydroxyhexacosanoic or
or-hydroxyoctacosanoic acid.
17. A process according to any one of Claims 13 to
16 wherein the titanium oxide is a titanium dioxide.
18. A process according to any one of claims 13 to
17 wherein the titanium dioxide has been surface-treated.
19. A process according to any one of claims 13 to
18 wherein the α-hydroxy acid is present in a concentration
of from 0.01 to 50 % by weight relative to the total weight
of the composition.
20. A process according to claim 19 wherein the
α-hydroxy acid is present in a concentration of from 0.5 to
20 % by weight relative to the total weight of the
composition.
21. A process according to any one of claims 13 to
20 wherein the titanium oxide is present in a concentration
of from 0.05 to 20 % by weight relative to the total weight
of the composition.
22. A process according to claim 21 wherein the
titanium oxide is present in a concentration of from 0.5 to
10 % by weight relative to the total weight of the
composition.
23. A process according to any one of claims 13 to
22 wherein the composition has a final pH of 2.5 to 6.
24. A process according to any one of claims 13 to
23 wherein the composition is a water-in-oil emulsion, an
oil-in-water emulsion, a microemulsion, a serum or a
dispersion of vesicles.
25. Use according to claim 1 wherein the
composition is substantially as described in any one of the Examples.
26. A process according to claim 13 wherein the
composition is substantially as described in any one of the
Examples.