Tanning preparation for the skin

Details Tanning preparation for the skin Tanning preparation for the skin

2002-08-14

2003-11-18

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S060000, C424S400000, C424S401000, C514S937000, C514S938000

Reexamination Certificate

active

06649149

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a tanning preparation for the skin comprising at least one tyrosine derivative of formula 1
where
R
1
=—H,— (CH
2
) X—CH
3
, x being an integer from 1 to 20,
R
2
=CH
3
CO—, CH
3
— (CH
2
) yCO—, y being an integer from 1 to 20, and an activator.
A preparation of this type is disclosed by DE-C-3 732 154. As this publication states, the skin pigment melanin is formed in the skin from the amino acid tyrosine. This reaction takes place under the influence of light, heat and oxygen, with the aid of the enzyme tyrosinase.
On the basis of this known biological process it was found that certain tyrosine derivatives, in combination with an activator as a substitute for the expensive and chemically unstable enzyme, may lead to the desired tanning of the skin, if used as a sunburn preparation. As an activator, this known preparation comprises an adenosine compound such as an ester or a salt of adenosine mono-, di- or triphosphoric acid.
Adenosine di- and triphosphate are known to be involved in various enzymatic reactions in the body, in particular in processes requiring energy such as the oxidation of sugars, proteins and fats.
DISCLOSURE OF THE INVENTION
Surprisingly, a tanning preparation has now been found for the skin wherein the activator used is not a substance which naturally occurs in the body and has an enzymatic reaction, but instead a compound which preferably has humectant activity.
The invention therefore relates, in a first embodiment, to a tanning preparation of the type mentioned at the outset, wherein the activator consists of an aliphatic polyol having at least 10 C atoms in the molecule.
Preferably, the aliphatic polyol consists of a hexadecanetriol, in particular phytantriol.
Phytantriol, or 3,7,11,15-tetramethyl-1,2,3-hexadecanetriol, is a compound which improves the moisture retention capability of the skin and of hair and-is therefore used in shampoos and hair conditioners; in this context, the Japanese patent application Kokai No JP-A2-61,236,737 can be mentioned.
It has now been found that an aliphatic polyol, and in particular phytantriol, improves the deposition of a tyrosine derivative as specified hereinabove on and in the skin, thereby allowing rapid and persistent, natural tanning of the skin to be achieved. Such an effect is rather surprising, all the more since only very small amounts of aliphatic polyol, in particular phytantriol, need be present in the tanning preparation.
Preferably, the tanning preparation according to the invention merely contains at least 0.01 wt % of phytantriol, it being noted in this context that even with this very small amount of phytantriol, rapid tanning of the skin is achieved.
Tyrosine derivatives which are particularly suitable for use in a tanning preparation according to the invention are N-acetyltyrosine; N-acetyltyrosine ethyl ester; N-myristoyltyrosine; N-myristoyltyrosine-myristylester; N-palmitoyltyrosine; N-palmitoyltyrosine-palmityl ester; N-stearoyltyrosine and N-stearoyltyrosine stearyl ester.
According to another expedient embodiment of a preparation according to the invention, the preparation further comprises riboflavin.
Riboflavin or vitamin B2 is 7,8-dimethyl-10 (D-1′-ribityl)-isoalloxazine and is a compound which in the body is converted into two coenzymes, viz. FMN and FAD, which are involved in numerous oxidation-reduction processes.
It should be noted that the use of riboflavin as an activator in a sunburn preparation comprising a tyrosine derivative is known per se from CH 642 537. An activator consisting of an aliphatic polyol, as described hereinabove, is not mentioned in this publication, however. The use of riboflavin according to the invention is optional, moreover, rather than mandatory as in CH 642 537.
According to yet another expedient embodiment of a preparation according to the invention, this preparation further comprises a W filter. The UV filter used can be any of the compounds suitable for this purpose in the customary quantities without any limitation.
The tanning preparation according to the invention can further be in the form of a gel, lotion, cream, foam, spray based on water and/or an aqueous alcohol and/or an aqueous glycol, or of an emulsion of the type O/W, W/O, O/W/O, etc.
Used as a solvent for aqueous solutions is, for example, water, aqueous ethanol, aqueous isopropanol, aqueous glycols or a mixture thereof. By adding a suitable emulsifier it is possible to form an emulsion or a gel, while an aerosol or a foam can be formed with the aid of a suitable propellant.
It should be noted that the tyrosine derivatives carrying relatively long-chain substituents are preferably dissolved in an oil. Examples of these are mineral oils such as paraffin oil, vegetable oil such as olive oil and animal oil such as squalene. Waxes such as beeswax and fat-dissolving glycols and polyglycols can also be used, however.
In addition, a tanning preparation according to the invention can comprise customary adjuvants, depending on the desired form of the preparation, such as surfactants, swelling agents or thickeners, emulsifiers and hydrolysed vegetable protein such as hydrolysed soya protein and hydrolysed wheat protein.
The invention further relates to a method of preparing a tanning preparation as described hereinabove, wherein a mixture is formed which comprises
5-15 wt % of N-acetyl-L-tyrosine,
0.5-5 wt % of phytantriol,
15-25 wt % of butylene glycol,
1-5 wt % of hydrolysed vegetable protein,
0.1-5 wt % of polysorbate-20,
0-5 wt % of riboflavin,
remainder: water/alcohol,
and this mixture is taken up in an amount of from 1 to 10%, preferably 5%, in a pharmacologically acceptable base to form a preparation for topical application.
According to a preferred embodiment of a method of preparing a tanning preparation according to the invention, a mixture is formed which comprises
10 wt % of N-acetyl-L-tyrosine,
20 wt % of butylene glycol,
2 wt % of phytantriol,
3 wt % of hydrolysed soya protein,
3 wt % of polysorbate-20,
1 wt % of riboflavin,
remainder: water,
and this mixture is taken up in an amount of 5%, in a water/ethanol/glycol mixture to form a lotion.
According to another embodiment, the present invention relates to a controlled release tanning preparation.
With respect to the phenomenon of controlled release preparations the following explanation is given.
Stable emulsions, produced for application in food, pharmacy, personal care and cosmetics, lacquers and coatings, paper products, etc., are characterized by the presence of a nematic, liquid crystalline structure.
The rationale for the existence of thermodynamically stable liquid crystalline (LC) structures is dependant on the temperature, and it is a boundary condition for stable emulsions that these LC structures are manifest in the temperature range of storage and application of the particular product.
Griffin defined in the 50's the famous HLB concept whereby it was stated that stable emulsions can be prepared when the HLB value was −10. Israelachvili et. al. (1975) showed that an optimum liquid crystalline phase exists in the case the emulsifier/emulsifier combination had an HLB value −10.
The nematic liquid crystalline structures reside in the continuous phase of emulsions. These are organised in double layers whereby the theme “like-dissolves-like” is applicable.
The double layers, relative to the continuous phase applicable, may be organised as:
H══L⇄L══H  (1)
L══H⇄H══L  (2)
whereby H represents the hydrophilic (water-loving) part hydrophlllc the surface active agent, and <<L >> represents the lipophilic (oil-loving) part of the surface active agent. Thus, structure (1) will reside in the water phase and is characteristic for Oil-in-Water (O/W) emulsions. Structure (2) will reside in the oil phase and is therefore characteristic for Water-in-Oil (W/O) emulsions.
The LC structure is present in the form of a sponge structure. A number of parameters are determining

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