Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2001-02-07
2002-06-04
Dees, Jose'G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S401000, C424S060000, C544S196000, C544S197000, C544S198000
Reexamination Certificate
active
06399047
ABSTRACT:
The present invention relates to benzoxazole derivatives and their use in cosmetic compositions and in the stabilization of synthetic polymers.
It is well known that sun radiations ranging from 290 to 400 nm are noxious for the organic materials, among which cutaneous tissue too. In fact, prolonged exposition to sun radiation is considered to be the main cause of the development of degenerative processes and of skin cancer forms. In particular, radiations of wavelength between 290 and 320 nm, so called UV-B radiations, cause erythema and sunburns, whose severity depends on exposure length.
It was ascertained that also the radiations ranging between 320 and 400 nm, so called UV-A, and responsible of skin tanning, can cause alterations and damages in the skin may not be disregarded, such as for example degenerative processes and even cancer forms; especially in case of sensible skins or in case of prolonged exposition to radiation.
It has also been demonstrated that the UV-A radiation other than causing damages to elastin and collagen, whose consequence is ageing of the skin, can also be the cause of a number of phototoxic and photoallergic reactions. Besides, the noxious action of UV-B may be enhanced by the presence of UV-A (see: Willis et al.: Journal of Investigative Dermatology vol. 59, 416, 1072).
By means of the use of particular compounds or of compositions containing these particular compounds, so called sunscreens or UV filters, capable of absorbing, at least partially, UV sunlight radiations, noxious effects on organic materials, in particular on synthetic polymers and on human skin can be prevented or at least attenuate and ageing of the same showed down. As protective agents a number of substances have been studied and experimented and a wide patent literature exists on this matter, wherein compounds belonging to different chemical classes capable of absorbing in the UV zone of sun radiation and particularly that between 290 and 360 nm are proposed.
Many compounds such as for example derivatives of cinnamic acid, 4-aminobenzoic acid, benzylydenecamphor, benzophenone and diphenylcyanoacrylic acid are well known and widely used in cosmetic preparations for the protection from sunburns and erythema due to noxious UV-B radiation.
Until recently the use of sunscreens for the protection from the UV-A radiation was practically unknown, other than some special cases of therapy. But recent studies show that also a continuous and intensive UV-A radiation can cause severe cutaneous damages, especially to persons having very sensible and delicate skin.
For the protection against UV-A, really suitable products are not yet available, even if in the patent literature some compounds have been proposed, but in practice, the outcome of these compounds may not be considered sufficiently positive.
2-Hydroxy-4-methoxybenzophenone is an often used commercial product, whose maximum absorption in the UV-A zone, at about 325 nm, is too low to give an effective protection, moreover its solubility in solvents usually used in cosmetics is very low thus making difficult its handling.
Another compound presently used in practice is a dibenzoylmethane derivative, but not only it is incompatible with many ingredients usually employed for cosmetic compositions, but also has the severe defect of not being sufficiently photostable (Int. J. Cosm. Science 10, 53 1988), therefore the sun formulations containing these compounds may not guarantee a sufficient protection from UV-A since the sunscreens are either too weak (such as the benzophenone derivative) or are degraded too quickly by the radiation itself (such as the dibenzoylmethane derivative).
Better results were obtained with the benzoxazole derivatives disclosed in U.S. Pat. No. 5,744,127.
However, the problems connected with the use of such UV sunscreens, particularly those concerning their solubility in the oily solvents conventionally used in cosmetic formulations, have not been solved.
A high solubility of UV filters in the cosmetic ingredients is, in fact, mandatory for the preparation of formulations having optimal sun protection factors.
DISCLOSURE OF THE INVENTION
It has now surprisingly been found that particular benzoxazole derivatives have such characteristics as to meet the present market requirements. In fact, in addition to good absorption, and therefore high protective efficiency in the zone between 320 and 360 nm, they also show good photostability, wide compatibility with the cosmetic ingredients and high solubility in the solvents usually employed in cosmetic compositions. The compounds according to the present invention have the following formula (I):
wherein
R and R1, which can be the same or different, are hydrogen, straight or branched C1-C8 alkyl, —OR3 wherein R3 is a C1-C4 alkyl group, —COOR4 wherein R4 is a straight or branched C1-C24 alkyl, a C7-C12 aralkyl or C5-C8 cycloalkyl group or a group of formula (II) or (III):
wherein
A is straight or branched C1-C8 alkyl, C5-C8 cycloalkyl, C6-C10 aryl optionally substituted with one or more C1-C4 alkyl, R5 and R6 are independently hydrogen or methyl, n can have values of 1 to 10, R2 is independently straight or branched C1-C18 alkyl, C5-12 cycloalkyl, optionally substituted with 1 to 3 straight or branched C1-C4 alkyl groups; an ammonium group optionally substituted with 1 to 4 C1-C4 alkyl groups or a group of formula (II) or (III) and the —CO—X—R2 moiety can be at the ortho or meta positions,
X is oxygen or NH.
A first group of preferred compounds comprises those wherein R and R1 have the meanings defined above and R2 is a straight or branched C1-C18 alkyl group.
A second group of preferred compounds comprises those wherein R and R1 have the meanings defined above and R2 is a group of formula (III).
A third group of preferred compounds comprises those wherein R and R1 have the meanings defined above, R2 is a straight or branched C2-C12 alkyl residue and X is oxygen.
Examples of alkyl groups are methyl, propyl, butyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl, heptadecyl, eicosanyl and the branched isomers thereof, optionally containing oxygen bridges in the form of ether groups. Particularly preferred are 2-octyldodecyl, 2-ethyldecyl, tert-butyl, 2-ethylhexyl, 1,1,3,3-tetramethylbutyl, isobutyl groups.
Examples of aralkyl groups are benzyl, phenylethyl, phenylpropyl, phenylhexyl, naphthylmethyl, naphthylethyl and the isomers thereof. Aryl is phenyl or naphthyl, any substitutions with alkyl groups, such as methyl, ethyl, isopropyl, tert-butyl, can be at the ortho, meta and para positions and on the naphthyl fused ring.
Examples of cycloalkyl groups are cyclopentyl, cyclohexyl, cyclooctyl.
The compounds according to the present invention absorb UV radiations intensely and particularly in the UV-A range, therefore small amounts of these compounds are sufficient to obtain cosmetic compositions with high SPF (Sun Protecting factor). SPF is directly related to the specific extinction and is determined in vivo on man or according to a in vitro method as described by B. Diffey J. Robson in J. Soc. Cosmet. Chem. 40, 127-133 (1989).
Moreover, the compounds of formula (I), also depending on the R
2
-R
4
substituents, show a wide absorption, which is not only confined in the UV-A range, but also extended to the UV-B range. Therefore, they can provide protection against both UV-A and UV-B radiations.
It is therefore a further object of the invention the use of the compounds of formula (I) as sunscreens in cosmetic compositions and as photostabilizing agents for the protection of synthetic polymers.
In particular, it is an object of the present invention the use of the compounds of formula (I) as sunscreens in the cosmetic treatment of the skin.
A further object of the present invention are cosmetic compositions containing at least a compound of formula (I).
The compounds according to the present invention can be prepared by reacting a compound of formula (IV):
with compounds of formula (V):
wherein R, R1, R2 and X have the meanings defined above, z is bromine or preferably chlo
Raspanti Giuseppe
Zanchi Giorgio
3V Sigma S.p.A.
Birch & Stewart Kolasch & Birch, LLP
Dees Jose'G.
George Konata M.
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