Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2002-07-18
2003-09-09
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S060000, C424S400000, C424S401000
Reexamination Certificate
active
06616918
ABSTRACT:
The present invention relates to a cosmetic and/or dermatological composition more particularly intended for artificially tanning and/or browning the skin and comprising, in a cosmetically acceptable support, at least one N-acyl amino acid ester and at least one self-tanning agent.
The present invention also relates to a cosmetic treatment process for artificially tanning or browning the skin and to the use of an N-acyl amino acid ester for improving the coloration and/or stability of a self-tanning agent.
The invention also relates to the use of these compositions for giving the skin a coloration close to that of natural tanning of the skin.
For the purposes of the present invention, the expression “self-tanning agent” means an agent which, when applied to the skin, especially to the face, gives a tanning effect that is more or less similar in appearance to that which may result from a prolonged exposure to sunlight (natural tan) or a UV lamp.
Nowadays, it is important to have a healthy appearance and tanned skin is always a sign of good health. However, natural tanning is not always desirable since it requires prolonged exposure to UV radiation, in particular to UV-A radiation which causes tanning of the skin, but is also liable to induce reactions or even impairment of the skin, especially in the case of sensitive skin or skin that is continually exposed to solar radiation: erythema, burns, loss of elasticity, appearance of wrinkles, premature ageing. It is thus desirable to find an alternative to natural tanning, which is compatible with the requirements of such skin.
Most of the cosmetic products intended for artificially tanning the skin are based on carbonyl derivatives allowing, by interaction with the amino acids of the skin, the formation of coloured products, among which mention is made of mono- or polycarbonyl compounds such as, for example, isatin, alloxan, ninhydrin, glyceraldehyde, mesotartaric aldehyde, glutaraldehyde, erythrulose and dihydroxyacetone (DHA).
DHA is a particularly advantageous product that is commonly used in cosmetics as an agent for artificially tanning the skin: when applied to the skin, especially to the face, it gives a tanning or browning effect that is similar in appearance to that which may result from a prolonged exposure to sunlight (natural tanning) or a UV lamp.
One drawback of DHA is the slow speed with which the coloration develops: in point of fact, it takes several hours (3 to 5 hours in general) for the coloration to be developed. The intensity of the coloration obtained on the skin and/or its staying power over time (resistance to washing) and/or the speed with which the coloration develops are often considered as insufficient by the users of DHA-based self-tanning compositions.
Another problem posed by DHA-based compositions is that they have the annoying tendency, that is more or less pronounced depending on the nature of the medium in which they are formulated, of degrading over time. These problems associated with the storage and/or conservation of DHA-based compositions are generally reflected in the end by an undesirable yellowing of these compositions.
There is thus increasing demand for fast-acting self-tanning products that give a coloration close to that of natural tanning.
Surprisingly and advantageously, the inventor has found that the use of an N-acyl amino acid ester improves the stability and coloration of compositions comprising a self-tanning agent. The colorations obtained are more chromatic and more stable over time, and also show good water resistance and good homogeneity.
The compositions according to the present invention also have the advantage of having improved cosmetic properties: they give the skin a feeling of softness and freshness, and prevent the skin from drying out and also from having an excessively greasy feel.
The composition according to the present invention comprises, in a cosmetically acceptable support, at least one N-acyl amino acid ester and at least one self-tanning agent.
A subject of the present invention is also the use of the composition according to the invention as a composition for tanning or browning the skin; and a cosmetic process for tanning or browning the skin such that it consists in applying to the skin an effective amount of a composition according to the invention.
Finally, the present invention also relates to the use of at least one N-acyl amino acid ester in compositions for artificially tanning and/or browning the skin, containing at least one self-tanning agent, in order to improve the coloration and/or stability of the self-tanning agent.
The compositions in accordance with the invention give an artificial coloration that is close to that of natural tanning in a short space of time. Thus, an immediate coloration is obtained, which allows visualization of the application and, consequently, better uniformity in the spreading of the composition onto the skin and thus of the resulting coloration. Furthermore, the artificial coloration obtained on the skin according to the invention is extremely close to that of a natural tan.
Other characteristics, aspects and advantages of the invention will become apparent on reading the detailed description that follows.
The N-acyl amino acid ester used in the present invention is an ester of formula:
R′
1
(CO)N(R′
2
)CH(R′
3
)(CH
2
)
n
(CO)OR′
4
in which:
n is an integer equal to 0, 1 or 2,
R′
1
represents a linear or branched C
5
to C
21
alkyl or alkenyl radical,
R′
2
represents a hydrogen atom or a C
1
to C
3
alkyl group,
R′
3
represents a radical chosen from the group formed by a hydrogen atom, a methyl group, an ethyl group and a linear or branched C
3
or C
4
alkyl radical,
R′
4
represents a linear or branched C
1
to C
10
alkyl radical or a linear or branched C
2
to C
10
alkenyl radical or a sterol residue.
In the above formula, the group R′
1
(CO)— is an acyl group of an acid preferably chosen from the group formed by capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, linoleic acid, linolenic acid, oleic acid, isostearic acid, 2-ethylhexanoic acid, coconut oil fatty acids, palm kernel oil fatty acids and hydrogenated palm kernel oil fatty acids. These fatty acids may also contain a hydroxyl group. Even more preferably, the fatty acid is lauric acid.
The portion —N(R′
2
)CH(R′
3
)(CH
2
)
n
(CO)— of the N-acyl amino acid ester is preferably chosen from the following amino acids: glycine, alanine, valine, leucine, isoleucine, serine, threonine, proline, hydroxyproline, &bgr;-alanine, aminobutyric acid, aminocaproic acid, sarcosine or N-methyl-&bgr;-alanine.
Even more preferably, the amino acid is sarcosine.
The portion of the N-acyl amino acid esters corresponding to the group OR′
4
may be obtained from alcohols chosen from the group formed by methanol, ethanol, propanol, isopropanol, butanol, tert-butanol, isobutanol, 3-methyl-1-butanol, 2-methyl-1-butanol, fusel oil, pentanol, hexanol, cyclohexanol, octanol, 2-ethylhexanol, decanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, cetostearyl alcohol, stearyl alcohol, oleyl alcohol, behenyl alcohol, jojoba alcohol, 2-hexadecyl alcohol, 2-octyldodecyl alcohol and isostearyl alcohol.
These N-acyl amino acid esters may be obtained in particular from natural sources of amino acids. In this case, the amino acids are obtained from the hydrolysis of natural proteins of plants (oat, wheat, soybean, palm or coconut) and then necessarily lead to mixtures of amino acids that will subsequently be esterified and then N-acylated. The preparation of such amino acids is more particularly described in patent application FR 2 796 550, which is incorporated herein by reference.
The amino acid ester that is more particularly preferred for its use in the present invention is isopropyl N-lauroylsarcosinate of formula:
CH
3
—(CH
2
)
10
CO—N(CH
3
)—CH
2
—COO—CH
2
—(CH
3
)
2
.
These amino acid esters and the process for synthesizing them are described in patent applications EP 1
Dodson Shelley A.
L'Oreal
Price D. Douglas
Steptoe & Johnson LLP
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