Drug – bio-affecting and body treating compositions – Bleach for live hair or skin
Reexamination Certificate
1999-09-10
2003-02-04
Travers, Russell (Department: 1617)
Drug, bio-affecting and body treating compositions
Bleach for live hair or skin
C424S401000
Reexamination Certificate
active
06514486
ABSTRACT:
The present invention relates to a composition for topical application to the skin and/or its superficial growths comprising, in a cosmetically and/or dermatologically acceptable medium, at least one compound comprising an iminophenol fragment and to the use of the said compound as depigmenting or lightening agent in a cosmetic and/or dermatological composition.
The colour of the human skin depends on various factors, in particular on the seasons of the year, race and sex, and it is mainly determined by the nature and the concentration of melanin produced by the melanocytes. Melanocytes are specialized cells which synthesize melanin via specific organelles, the melanosomes. In addition, at different periods in their lives, some people witness the appearance on the skin and more especially on the hands of darker and/or more highly coloured blemishes which give the skin a heterogeneous appearance. These blemishes are also due to a high concentration of melanin in the keratinocytes situated at the surface of the skin.
In the same way, the colour of the body hairs and of the hair is due to melanin, when the body hairs or the hair are dark, some people want these to be lighter. This is particularly important for body hairs, which are less visible when they are light than when they are dark.
The mechanism of formation of the pigmentation of the skin, of the body hairs and of the hair, that is to say of the formation of melanin, is particularly complex and involves, schematically, the following main stages:
Tyrosine→Dopa→Dopaquinone→Dopachrome→Melanin
Tyrosinase (monophenol dihydroxyl phenylalanine:oxygen oxidoreductase EC 1.14.18.1) is the essential enzyme involved in this sequence of reactions. In particular, it catalyses the conversion reaction of tyrosine to Dopa (dihydroxyphenylalanine), by virtue of its hydroxylase activity, and the conversion reaction of Dopa to dopaquinone, by virtue of its oxidase activity. This tyrosinase only acts when it is in the maturation state under the effect of certain biological factors.
A substance is recognized as depigmenting if it acts directly on the vitality of the epidermal melanocytes where melanogenesis takes place and/or if it interferes with one of the stages in the biosynthesis of melanin, either by inhibiting one of the enzymes involved in melanogenesis or by being inserted as structural analogue of one of the chemical compounds in the sequence for the synthesis of melanin, which sequence can then be blocked and thus ensure depigmentation.
The substances most commonly used as depigmenting agents are more particularly hydroquinone and its derivatives, in particular its ethers, such as hydroquinone monomethyl ether and monoethyl ether. These compounds, although they are certain to be effective, are unfortunately not free of side effects due to their toxicity, which can make their use problematic or indeed dangerous. This toxicity arises from their intervention in fundamental mechanisms of melanogenesis, killing cells which then risk disturbing their biological environment and which consequently oblige the skin to discharge them, producing toxins.
Thus, hydroquinone is a compound which is particularly irritating and cytotoxic for melanocytes, the complete or partial replacement of which has been envisaged by many writers.
A search has thus been carried out for substances which do not interfere in the mechanism of melanogenesis but which act upstream on tyrosinase, preventing its activation, and which are, for this reason, much less toxic. Use is commonly made, as inhibitor of the activation of tyrosinase, of kojic acid, which complexes the copper present in the active site of this enzyme. Unfortunately, this compound can cause allergic reactions (“Contact allergy to kojic acid in skin care products”, Nakagawa M. et al., in Contact Dermatitis, Jan. 95, Vol. 42 (1), pp. 9-13). This compound is also unstable in solution, which somewhat complicates the manufacture of the composition.
The use of inoffensive topical depigmenting substances which are highly effective is very particularly sought after with a view to treating regional hyperpigmentations by melanocytic hyperactivity, such as idiopathic melasmas, arising during pregnancy (“mask of pregnancy” or chloasma) or oestrone/progestogen contraception, localized hyperpigmentation by benign melanocytic hyperactivity and proliferation, such as senile pigmental blemishes known as actinic lentigines, accidental hyperpigmentations or depigmentations, possibly due to photo-sensitization or to post-lesional healing, as well as certain leucodermas, such as vitiligo. For the latter conditions (healing which can result in a scar giving the skin a whiter appearance and leucodermas), for want of being able to repigment the damaged skin, the end result is to depigment the remaining normal skin regions to give the whole skin a homogeneous white colouring.
The need consequently remains for a novel lightening agent for the human skin, body hairs and/or hair with an action as effective as those known but which does not have their disadvantages, that is to say which is non-irritating, non-toxic and/or non-allergizing for the skin and which is stable in a composition.
The Applicant Company has unexpectedly found that compounds comprising an iminophenol fragment exhibit a depigmenting activity, even at low concentrations, without showing cytotoxicity.
Compounds with an iminophenol fragment which can be used as antipathogens, antivirals or antibacterials and which are intended to be administered orally or parenterally are known from U.S. Pat. No. 3,182,053. In addition, certain compounds with an iminophenol fragment which can be used as antioxidants for fuel, rubber and other auto-oxidizable materials are known from U.S. Pat. No. 2,220,065.
However, to the knowledge of the Applicant Company, provision has never yet been made to administer compounds with an iminophenol fragment by the topical route, in particular for the purpose of lightening or depigmenting the skin or its superficial growths. The subject-matter of the present invention is therefore a composition for topical application to the skin and/or its superficial growths comprising, in a cosmetically and/or dermatologically acceptable medium, at least one compound of following formula (I):
in which:
R represents a group chosen from:
the hydrogen atom;
a saturated or unsaturated, linear, branched or cyclic C
1
-C
24
alkyl group which is optionally hydroxylated by one or more hydroxyl functional groups;
an aryl group which is unsubstituted or substituted by one or more functional groups chosen from: —OH, NH
2
, —COOH, —NO
2
, —OR
5
with R
5
=C
1
-C
24
alkyl, —COOR
6
with R
6
=C
1
-C
24
alkyl, or —NR
7
R
8
with R
7
=H or C
1
-C
24
alkyl and R
8
=H or C
1
-C
24
alkyl;
a —COR
9
group, R
9
representing a saturated or unsaturated, linear, branched or cyclic C
1
-C
24
alkyl group which is optionally hydroxylated by one or more hydroxyl functional groups or an aryl group which is unsubstituted or substituted by one or more functional groups chosen from —OH, —NH
2
, —COOH, —NO
2
, —OR
5
, —COOR
6
or —NR
7
R
8
in which R
5
, R
6
, R
7
and R
8
have the same definition as above;
R
1
, R
2
, R
3
and R
4
, which are identical or different, represent a group chosen from:
the hydrogen atom;
a saturated or unsaturated, linear, branched or cyclic C
1
-C
24
alkyl group which is optionally hydroxylated by one or more hydroxyl functional groups;
an aryl group which is unsubstituted or substituted by one or more functional groups chosen from —OH, —NH
2
, —COOH, —NO
2
, —OR
5
, —COOR
6
or —NR
7
R
8
in which R
5
, R
6
, R
7
and R
8
have the same definition as above;
a group chosen from: —OH, —OQ
1
, —COQ
2
, —COOQ
3
, —NQ
4
Q
5
, —CONQ
6
Q
7
, —SQ
8
or —CH
2
OQ
9
, Q
1
, Q
2
, Q
3
, Q
4
Q
5
, Q
6
, Q
7
, Q
8
and Q
9
being chosen from the hydrogen atom, saturated or unsaturated, linear, branched or cyclic C
1
-C
24
alkyl groups which are optionally substituted by one or more hydroxyl groups or aryls which a
Blaise Christian
Tuloup Remy
Berman Alysia
L'Oreal
Travers Russell
LandOfFree
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