Topical cosmetic compositions comprising benzaldoximes

Details Topical cosmetic compositions comprising benzaldoximes Topical cosmetic compositions comprising benzaldoximes

2000-06-30

2002-05-28

Dees, Jose′ G. (Department: 1616)

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

C424S060000, C424S070100, C424S401000, C514S507000

Reexamination Certificate

active

06395260

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to topical cosmetic compositions, in particular, skin lightening compositions, comprising benzaldoximes having at least one aromatic hydroxyl or alkoxy group for cosmetic or dermatological applications.
BACKGROUND OF THE INVENTION
Skin-lightening active ingredients somehow interfere with melanin metabolism or catabolism. The melanins, which are usually brown to black in color, are formed in the melanocytes of the skin, transferred to the keratinocytes and cause the coloration of skin or hair. The brown-black eumelanins are formed in mammals predominantly from hydroxy-substituted aromatic amino acids such as L-tyrosine and L-DOPA, and the yellow to red pheomelanins are additionally formed from sulfur-containing molecules (Cosmetics & Toiletries 1996, 111 (5), 43-51). Starting from L-tyrosines, the copper-containing key enzyme tyrosinase forms L-3,4-dihydroxyphenylalanine (
L
-DOPA), which for its part is oxidized again by the tyrosinase via the red-brown dopaquinone to give melanin. A comparison of tyrosinases from plants, fungi and mammals shows that the mechanism and the substrate specificity is comparable in all of the tyrosinases examined.
If, for some reason, the melanin-forming melanocytes are not distributed evenly in the human skin, pigmentation spots form, which are either lighter or darker than the surrounding areas of skin. In order to overcome this problem, skin lightening compositions are offered on the market which help to at least partially even out pigmentation spots. In addition, many people have a desire to lighten their naturally dark skin color. Very safe and effective skin lightening compositions are required for this purpose. Many skin lightening compositions comprise tyrosinase inhibitors of greater or lesser strength.
Commercially available skin lightening compositions comprise, in particular, hydroquinone, hydroquinone derivatives, such as, for example, arbutin, vitamin C, derivatives of ascorbic acid, such as, for example, ascorbyl palmitate, kojic acid and derivatives of kojic acid, such as, for example, kojic acid dipalmitate.
One of the most frequently used skin lighteners is hydroquinone. However, the substance has a cytotoxic effect towards melanocytes and can damage the skin. For this reason, such preparations are no longer authorized for cosmetic applications in, for example, Japan and South Africa. In addition, hydroquinone is very oxidation-sensitive and can only be stabilized, with difficulty, in cosmetic formulations.
Vitamin C and ascorbic acid derivatives have only an inadequate action on the skin. Further, they do not act directly as tyrosinase inhibitors, but reduce the colored intermediates of melanin biosynthesis.
Kojic acid (5-hydroxy-2-hydroxymethyl-4-pyranone) is a tyrosinase inhibitor which, by chelating the copper atoms of the enzyme, inhibits the catalytic activity of the latter; it is used in commercial skin lightening compositions. The substance is formed predominantly in Aspergillus cultures and can only be isolated therefrom in small amounts.
SUMMARY OF THE INVENTION
The object of the present invention was to find low-cost, easy-to-prepare, highly effective tyrosinase inhibitors which can be used as active ingredients in skin lightening compositions.
The invention relates to topical cosmetic compositions comprising benzaldoximes of the general formula
geometric isomers thereof or mixtures of these isomers
wherein
R
1
, R
5
independently of one another are hydrogen atoms or alkyl groups having from 1 to 4 carbon atoms,
R
2
, R
3
and R
4
independently of one another are hydrogen atoms, hydroxyl groups, alkyl groups having from 1 to 4 carbon atoms or —O—R
7
groups, where R
7
can be an alkyl group having from 1 to 4 carbon atoms or an arylalkyl group having from 7 to 10 carbon atoms,
with the proviso that at least one of the radicals R
2
to R
4
is a hydroxyl group or an —O—R
7
group, where R
7
is as defined above,
and
R
6
is a hydrogen atom, an alkyl or alkenyl group having from 1 to 12 carbon atoms or an optionally substituted aryl or arylalkyl group having from 7 to 10 carbon atoms or an optionally substituted heteroaryl or heteroarylalkyl group having from 2 to 10 carbon atoms which contain one or more heteroatoms from the group consisting of sulfur, nitrogen and oxygen.
DETAILED DESCRIPTION OF THE INVENTION
Preference is given to topical cosmetic compositions comprising benzaldoximes of the general formula
geometric isomers thereof or mixtures of these isomers, wherein
R
1
and R
5
are hydrogen,
and
R
2
, R
3
and R
4
independently of one another are hydrogen atoms, hydroxyl groups, alkyl groups having from 1 to 4 carbon atoms or —O—R
7
groups, where R
7
can be an alkyl group having from 1 to 4 carbon atoms or an arylalkyl group having from 7 to 10 carbon atoms,
with the proviso that at least one of the radicals R
2
to R
4
is a hydroxyl group or an —O—R
7
group, where R
7
is as defined above,
and
R
6
is a hydrogen atom, an alkyl or alkenyl group having from 1 to 12 carbon atoms or an optionally substituted arylalkyl group having from 7 to 10 carbon atoms.
Particular preference is given to topical cosmetic compositions comprising benzaldoximes chosen from the group comprising, for example,
4-hydroxybenzaldoxime;
3,4,5-trihydroxybenzaldoxime;
3-hydroxy-4-methoxybenzaldehyde O-ethyloxime;
3-ethoxy-4-hydroxybenzaldehyde O-ethyloxime;
3,4-dihydroxybenzaldoxime;
3-hydroxy-4-methoxybenzaldoxime;
4-hydroxy-3-methoxybenzaldehyde O-ethyloxime;
3,4-dihydroxybenzaldehyde O-(4-methylbenzyl)-oxime;
3-ethoxy-4-hydroxybenzaldoxime;
4-hydroxy-3-methoxybenzaldoxime;
3,4-dihydroxybenzaldehyde O-ethyloxime;
but not limited thereto.
Surprisingly, we have now found that the benzaldoximes present in the topical compositions according to the present invention are particularly effective tyrosinase inhibitors. In particular, many of the benzaldoximes according to the present invention are significantly more effective than kojic acid. They can, therefore, be used as active ingredients in cosmetic or dermatological skin lightening compositions.
The topical cosmetic compositions according to the present invention, in particular, skin lightening compositions comprising the benzaldoximes are prepared by customary methods known per se by incorporating one or more of the benzaldoximes according to the present invention into cosmetic or dermatological formulations which have the customary composition and, in addition to the skin lightening action, can also be used for the treatment, care and cleansing of skin or hair and as make-up products in decorative cosmetics.
Accordingly, the present invention also relates to topical cosmetic compositions, in particular, cosmetic and dermatological skin lightening compositions, which comprise the benzaldoximes, according to the present invention, in an effective amount alongside other, otherwise customary composition constituents. They comprise from 0.01% by weight to 30% by weight, preferably from 0.01 to 20% by weight, but, in particular, from 0.01% by weight to 5% by weight, based on the total weight of the formulation, of the benzaldoximes according to the present invention and can be in the form of “water-in-oil”, “oil-in-water”, “water-in-oil-in-water” or “oil-in-water-in-oil” emulsions, microemulsions, gels, solutions, e.g., in oils, alcohols or silicone oils, sticks, soaps, aerosols, sprays and also foams. Further customary cosmetic auxiliaries and additives can be present in amounts from 5 to 99% by weight, preferably from 10 to 80% by weight, based on the total weight of the formulation. In addition, the formulations can comprise water in an amount up to 99.99% by weight, preferably from 5 to 80% by weight, based on the total weight of the formulation.
Some of the benzaldoximes present in the skin lightening compositions according to the present invention are known. The known benzaldoximes according to the present invention are described, for example, in Chem. Ber. 1883, 16, 1780 to 1787, Chem. Ber. 1941, 74, 79, 87 and 89, Chem. Ber. 1922, 55,

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