Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2001-07-16
2003-08-05
Padmanabhan, Sreeni (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S059000, C560S001000, C560S055000, C562S400000, C568S306000
Reexamination Certificate
active
06602515
ABSTRACT:
BACKGROUND OF THE INVENTION
Topical sunscreen compositions are commonly used during outdoor work or leisure as a means for providing protection of exposed skin against acute and chronic adverse effects of solar radiation such as sunburn, cancer and photo-aging. Many effective sunscreen preparations are sold commercially or are described in cosmetic or pharmaceutical literature. In general sunscreen preparations are formulated as creams, lotions or oils containing as the active agent an ultra violet radiation absorbing chemical compound. The sunscreen functions by blocking passage of ultra violet radiation thereby preventing its penetration into the skin.
According to Zecchino et al. (U.S. Pat. No. 5,008,100), sunscreen agents may be characterized in the order of decreasing effectiveness as either highly chromophoric (monomeric organic compounds and inorganic compounds such as titanium dioxide) and minimally chromophoric (polymeric organic solids).
Organic sunscreens are classified into UV-A filters, UV-B filters or broad spectrum filters (UV-A and UV-B functionality in a single molecule) depending on the type of radiation they absorb. UV-A sunscreens absorb radiation in the 320 to 400 mn regions of the ultra violet spectrum and UV-B sunscreens absorb radiation in the 290 to 320 nm regions of the ultra violet spectrum.
Broad band sunscreens (UV-A and UV-B functionality) absorb radiation in the 290 to 400 nm region of the ultra violet spectrum and have two maximums, one in the UV-B region and the other in the UV-A region.
Representative references related to UV sunscreens are:
U.S. Pat. No. 3,278,448, which discloses cinnamic acid derivatives such as 4-hydroxy, 3-5-ditertbutyl-alphacarbethoxy-cinnamic acid ether ester in column 2, line 20;
U.S. Pat. No. 3,538,226, which describes cinnamic acid alkyl ester derivatives at column 1, lines 15-31 and column 2, lines 1-12 and column 3, lines 30-55 and 60;
U.S. Pat. No. 5,175,340, which describes cinnamic acid alkyl esters having hydroxy radicals and alkoxy radicals on the phenyl ring, and
U.S. Pat. No. 5,830,441, which describes UV absorbents containing a cyano or cinnamyl moiety by the generic formula at col. 2, lines 1-21.
Other references which disclose cinnamide compounds include U.S. Pat. Nos. 5,601,811, 4,335,054, 5,124,354, 5,294,643 and 5,514,711.
Unfortunately, some of the highly chromophoric monomeric organic compounds employed in sunscreen compositions are not photostable and the protection from sun damage is lost. For example, Avobenzone, a UV-A sunscreen, is highly photo-unstable. In addition to lack of photostability of many organic sunscreens, they do not possess an antioxidant property which is essential for protecting skin or hair.
The ideal sunscreen formulation should be nontoxic and non-irritating to the skin tissue and be capable of convenient application in a uniform continuous film. The product should be chemically and physically stable so as to provide an acceptable shelf life upon storage. It is particularly desirable that the preparation should retain its protective effect over a prolonged period after application. Thus, the active agent when present on the skin must be resistant to chemical and/or photo degradation.
Techniques for stabilizing UV absorbent compositions are known. Representative disclosures in this area include U.S. Pat. Nos. 5,567,418, 5,538,716, 5,951,968 and 5,670,140.
Antioxidants are believed to function by providing protection from free-radical damage. To be an effective quencher, it is believed the antioxidant must be present in an adequate concentration at the site of free radical generation. Since antioxidants are used in low concentrations and are a separate ingredient, they may not be available at the site of generation, thereby reducing the desired skin protection. Based on these drawbacks, it is desirable to provide the antioxidant and photostable sunscreen functionality in a single molecule to enhance the effectiveness of the antioxidant properties.
SUMMARY OF THE INVENTION
There is provided by the present invention compounds with sunscreen activity, i.e. they are chromophoric within the ultra violet radiation range of from 290-400 nm and they also exhibit antioxidant properties. These compounds are represented by general formula I
In formula I, A is a moiety which provides chromophoric properties within the UV radiation range of 290-400 nm. This moiety comprises one divalent group or two monovalent groups with at least one group having carbonyl (C═O) functionality. For formula I, each R is independently linear or branched C
1
-C
8
alkyl. The one or more compounds of formula I can preferably stabilize an additional sunscreening agent against photodegradation from exposure to sunlight. Preferred compounds are of formula II below.
For formula II,
each R is independently linear or branched C
1
to C
8
alkyl;
R
1
is selected from the group consisting —C(O)CH
3
, —CO
2
R
3
, —C(O)NH
2
, —C(O)N(R
4
)
2
, and —CN;
X is O or NH;
R
2
is linear or branched C
1
to C
20
alkyl;
R
3
is linear or branched C
1
to C
20
alkyl; and
each R
4
is independently hydrogen or linear or branched C
1
to C
8
alkyl.
Included within the preferred compounds are those of formula II wherein R is linear or branched C
1
-C
4
alkyl, X is oxygen and R
2
is linear or branched C
1
-C
12
alkyl. Of these compounds, those more preferred have R
1
as C(O)CH
3
or CO
2
R
3
wherein R
3
is a linear or branched C
1
to C
4
alkyl. For compounds wherein R
1
is C(O)N(R
4
)
2
, R
4
is preferably hydrogen or a linear or branched C
1
-C
4
alkyl.
While compounds having from C
1
-C
4
alkyl groups for R
2
and R
3
are preferred, significant utility can be obtained from compounds wherein R
2
and R
3
are linear or branched C
8
to C
20
alkyl or C
12
to C
20
alkyl groups.
Another preferred class of compounds are those of formulae III and IV wherein R
1
and R
2
are as defined for formula I with R
3
being C
1
-C
8
alkyl and R
4
being C
1
-C
4
alkyl.
Preferred compounds include those selected from the group consisting of ethyl- alpha- cyano-3,5-dimethoxy-4-hydroxy cinnamate, ethyl- alpha- acetyl-3,5-dimethoxy-4-hydroxy cinnamate, iso-propyl-alpha-acetyl-3,5-dimethoxy-4-hydroxy cinnamate, iso-amyl-alpha-acetyl-3,5-dimethoxy-4-hydroxy cinnamate, 2-ethylhexyl-alpha-acetyl-3,5-dimethoxy-4-hydroxy cinnamate, diethyl-3,5-dimethoxy-4-hydroxy benzylidene malonate, di-(2-ethylhexyl)-3,5-dimethoxy-4-hydroxy benzylidene malonate, diisoamyl-3,5- dimethoxy-4- hydroxy benzylidene malonate, didodecyl-3,5-dimethoxy-4-hydroxy benzylidene malonate, dipalmitoyl-3,5-dimethoxy-4-hydroxy benzylidene malonate, and di-isopropyl-3,5-dimethoxy-4-hydroxy benzylidene malonate.
The present invention also provides sunscreen formulations which comprise a compound of formula I, II, III and/or IV. These sunscreen formulations are effective in absorbing illumination in the range of wavelengths of 320 nm and above. Amounts of the compounds of formula I, II, III and/or within such compositions typically range from 0.1 to 40 wt % based on the total weight of the sunscreen. These sunscreen formulations can contain one or more additional organic sunscreen agents for filtering UV-B or UV-A rays or they may additionally contain one or more metal oxide sunscreen agents such as titanium dioxide or zinc oxide.
These sunscreen formulations may additionally contain a carrier and at least one component selected from the group consisting of dispersing agents, preservatives, anti-foams, perfumes, oils, waxes, propellants, dyes, pigment emulsifiers, surfactants, thickeners, humectants, exfoliants and emollients. These sunscreen formulations may be in the form of a cosmetic composition with a cosmetically acceptable carrier and one or more cosmetic adjuvants. The sunscreen formulation can optionally have conventional antioxidants or other stabilizers which do not have UV absorbing characteristics.
Methods of using these sunscreen compositions and methods for improving the photostability of sunscreen formulations are also provided. The methods of usi
EM Industries
Millen White Zelano & Branigan P.C.
Padmanabhan Sreeni
Willis Michael A.
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