Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-01-31
2002-06-18
Higel, Floyd D. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C548S483000, C549S068000, C549S079000, C549S274000, C549S480000, C560S043000
Reexamination Certificate
active
06407247
ABSTRACT:
The invention relates to the use of enamine derivatives as photo-stable UV filters in cosmetic and pharmaceutical formulations for the protection of the human sepidermis or human hair from UV radiation, specifically that ranging from 320 to 400 nm.
It is the purpose of the screening agents used in cosmetic and pharmaceutical formulations to prevent injurious influences of sunlight on the human skin or at least to reduce the effects thereof. On the other hand these screening agents also serve to protect other ingredients from destruction or degradation due to UV radiation. In hair-care formulations it is desirable to reduce damage to the keratin fiber caused by UV radiation.
The sunlight reaching the earth's surface has a concentration of UV-B radiation (from 280 to 320 nm) and UV-A radiation (>320 nm ), which follow directly on the visible light range. The effect thereof on the human skin is demonstrated by sunburn, this being particularly so in the case of UV-B radiation. Accordingly the market offers a relatively large number of substances which absorb UV-B radiation and thus prevent sunburn.
Dermatological investigations have now shown that UV-A radiation can also cause skin lesions and allergies by, for example, causing damage to keratin or elastin. This means that the elasticity and water-holding capacity of the skin are reduced, ie the skin is less supple and tends to form wrinkles. The remarkably high abundance of skin cancer in areas of strong sunshine clearly shows that damage to hereditary factors in the cells is caused by sunlight, specifically by UV-A radiation. Knowing all this, it is clear that the development of efficient filtering substances for the UV-A range is necessary.
There is a growing need for screening agents for cosmetic and pharmaceutical formulations which may primarily serve as UV-A filters and whose absorption maxima should therefore be in the range of from approximately 320 to 380 nm. In order to achieve the desired action with a minimal amount of material, such screening agents should additionally show a high degree of specific absorption.
Furthermore, screening agents for cosmetic preparations must also satisfy a large number of other demands, for example show good solubility in cosmetic oils, high stability of the emulsions prepared therefrom, toxicological acceptability and also little intrinsic odor and little intrinsic color.
Another requirement to be satisfied by screening agents is: adequate photostability. However, this is not or only insufficiently provided by the hitherto available screening agents for the absorption of UV-A radiation.
In French patent specification No. 2,440,933, 4-(1,1-dimethylethyl)-4-methoxy-dibenzoylmethane is described as a UV-A filter. It is proposed therein that this specific UV-A filter, which is sold by GIVAUDAN under the trade name “PARSOL 1789”, be used in combination with UV-B filters in order to absorb all of the UV radiation having a wavelength from 280 to 380 nm.
However, this UV-A filter, when used alone or in combination with UV-B filters, is not sufficiently photochemically stable to ensure constant protection of the skin during a lengthy sunbath, which makes it necessary to re-apply it to the skin at regular short intervals, if it is desired to achieve effective protection of the skin from the entire range of UV radiation.
EP 0,514,491 therefore proposes that the insufficiently photo-stable UV-A filters be stabilized by the addition of 2-cyano-3,3-diphenylacrylates, which are themselves active as filters for the UV-B range.
Furthermore, EP 251,398 has already proposed that chromophores that are capable of absorbing UV-A radiation and UV-B radiation be combined to a single molecule by a connecting link. This suffers from the drawbacks that free combination of UV-A filters and UV-B filters in cosmetic formulations is no longer possible and that difficulties encountered in chemically linking the chromophores permit the use of only certain combinations.
It is thus an object of the present invention to propose screening agents for cosmetic and pharmaceutical purposes which achieve high absorption in the UV-A range and which are photo-stable, have little intrinsic color ie exhibit a well-defined band structure and are soluble in oil or water depending on the substituent incorporated.
This object is achieved, according to the invention, by the use of compounds of formula I
in which the C═C double bond is present in E and/or Z configuration and the variables have the following meanings:
R
1
denotes COOR
5
, COR
5
, CONR
5
R
6
, CN, O═S(—R
5
)═O, O═S(—OR
5
)═O, R
7
O—P(—OR
8
)═O;
R
2
denotes COOR
6
, COR
6
, CONR
5
R
6
, CN, O═S(—R
8
)═O, O═S(═OR
6
)═O, R
7
O—P(—OR
8
)═O;
R
3
denotes hydrogen, an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic radical having in each case up to 18 carbon atoms;
R
4
denotes an optionally substituted aromatic or heteroaromatic radical containing from 5 to 12 ring atoms;
R
5
to
R
8
independently denote hydrogen, an open-chain or branched-chain aliphatic, araliphatic, cycloaliphatic or optionally substituted aromatic radical containing in each case up to 18 carbon atoms,
where the variables R
3
to R
8
may also form, together with the carbon atoms to which they are attached, a 5-membered or 6-membered ring, which may be anellated if desired,
as UV filters, particularly UV-A filters, in cosmetic and pharmaceutical formulations-for the protection of the human skin or human hair from solar radiation, alone or together with compounds known per se in cosmetic and pharmaceutical formulations and capable of absorbing radiation in the UV range.
We prefer those compounds of formula I, in which R
3
stands for hydrogen, R
1
for CN, COOR
5
and COR
5
and R
2
for CN, COOR
6
and COR
6
, where R
5
and R
6
independently denote open-chain or branched-chain aliphatic or optionally substituted aromatic radicals containing up to 8 carbon atoms.
We particularly prefer the use of compounds of formula I in which R
3
stands for shydrogen, R
1
for CN, COOR
5
and COR
5
and R
2
for CN, COOR
6
and COR
6
, where R
5
and R
6
independently denote open-chain or branched-chain aliphatic or optionally substituted aromatic radicals containing up to 8 carbon atoms and R
4
stands for an optionally substituted aromatic or heteroaromatic radical containing up to 10 carbon atoms in the ring, particularly a substituted phenyl, thienyl, furyl, pyridyl, indolyl or naphthylene radical and more preferably stands for an optionally substituted phenyl or thienyl radical.
Suitable substituents comprise both lipophilic and hydrophilic substituents containing, eg up to 20 carbon atoms. Lipophilic radicals, ie radicals which improve the oil-solubility of the compounds of formula I are, for example, aliphatic or cycloaliphatic radicals, particularly alkyl radicals containing from 1 to 18 carbon atoms, alkoxy, monoalkylamino and dialkylamino, alkoxycarbonyl, monoalkyl- and dialkyl-aminocarbonyl, monoalkyl- and dialkyl-aminosulfonyl radicals, and also cyanogeno, nitro, bromo, chloro, iodo or fluoro substituents.
Hydrophilic radicals, ie radicals which make the compounds of formula I soluble in water, are, for example, carboxy and sulfoxy radicals and particularly their salts with any physiologically acceptable cation, such as the alkali metal salts or the trialkylammonium salts, such as tri(hydroxyalkyl)ammonium salts or 2-methylpropan-1-ol-2-ammonium salts. Other suitable radicals are ammonium, particularly alkylammonium, radicals containing any physiologically acceptable anion.
Suitable alkoxy radicals are those containing from 1 to 12 carbon atoms, preferably those having from 1 to 8 carbon atoms.
Specific examples thereof are:
methoxy
ethoxy
isopropoxy
n-propoxy
1-methlypropoxy
n-butoxy
n-pentoxy
2-methylpropoxy
3-methylbutoxy
1,1-dimethylpropoxy
2,2-dimethylpropoxy
hexoxy
1-methyl-1-ethylpropoxy
heptoxy
octoxy
2-ethylhexoxy
Suitable monoalkylamino or dialkylamino radicals are for example those containing alkyl r
Aumüller Alexander
Habeck Thorsten
Schehlmann Volker
Westenfelder Horst
Wünsch Thomas
BASF - Aktiengesellschaft
Higel Floyd D.
Keil & Weinkauf
Sackey Ebenezer
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