Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2001-03-05
2002-06-04
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S060000, C424S401000
Reexamination Certificate
active
06399046
ABSTRACT:
The present invention relates to cosmetic and dermatological preparations for tanning the skin, in particular to those which also offer protection against UV radiation.
The harmful effect of the ultraviolet part of solar radiation on the skin is generally known. While rays having a wavelength of less than 290 nm (the UVC region), are absorbed by the ozone layer in the earth's atmosphere, rays in the range between 290 nm and 320 nm, the UVB region, cause erythema, simple sunburn or even burns of varying severity.
The erythema activity maximum of sunlight is given as the relatively narrow region around 308 nm.
Numerous compounds are known for protecting against UVB radiation; these are mostly derivatives of 3-benzylidenecamphor, of 4-aminobenzoic acid, of cinnamic acid, of salicylic acid, of benzophenone and also of 2-phenylbenzimidazole.
It is also important to have available filter substances for the range between about 320 nm and about 400 nm, the UVA region, since its rays can also cause damage. Thus, it has been found that UVA radiation leads to damage of the elastic and collagenous fibers of connective tissue, causing premature aging of the skin, and that it is to be regarded as a cause of numerous phototoxic and photoallergic reactions. The harmful effect of UVB radiation can be intensified by UVA radiation. In addition, UVA radiation can cause skin damage by damaging keratin or elastin in the skin. This leads to a reduction in elasticity and water-storage capacity, i.e. the skin becomes less supple and tends towards wrinkling. The notably high incidence of skin cancer in regions where solar irradiation is strong indicates that damage to the genetic information in cells is also apparently caused by sunlight, specifically by UVA radiation.
However, UV radiation can also lead to photochemical reactions, the photochemical reaction products interfering with the skin's metabolism.
Such photochemical reaction products are predominantly free-radical compounds, e.g. hydroxyl radicals. Undefined free-radical photoproducts which are formed in the skin itself can also display uncontrolled secondary reactions as a result of their high reactivity. However, singlet oxygen, a non-free-radical excited state of the oxygen molecule, can also arise during UV irradiation, as can short-lived epoxides and many others. Singlet oxygen, for example, differs from the normal triplet oxygen (free-radical ground state) by virtue of its increased reactivity. However, excited, reactive (free-radical) triplet states of the oxygen molecule also exist.
UV radiation is also a type of ionizing radiation. There is therefore the risk that ionic species may also arise during UV exposure, which then, for their part, are capable of oxidative intervention in the biochemical processes.
The pigmentation of human skin is essentially brought about by the presence of melanin. Melanin and its degradation products (melanoids), carotene, degree of perfusion, and the condition and thickness of the Stratum corneum and other skin layers permit skin shades from virtually white (in cases of reduced filling or in cases of an absence of blood vessels) or yellowish via pale brown-reddish, bluish to brown of different shades and finally almost black. The individual regions of the skin display differing depths of shade as a result of varying amounts of melanin.
Natural melanin protects the skin from penetrating UV radiation. The number of melanin granules produced in the melanocytes determines whether a person has pale skin or dark skin. In cases of strong pigmentation (e.g. in colored races, but also in those with pale skin following UV irradiation) melanin is also to be found in the Stratum spinosum and even in the Stratum corneum. It attenuates the UV radiation by up to about 90% before it reaches the corium.
Depending on their sensitivity to light, the skin types below are normally differentiated:
Skin type I never tans, always burns.
Skin type II rarely tans, burns easily.
Skin type III tans averagely well.
Skin type IV tans easily to give a lasting tan, almost never burns.
Skin type V dark, often almost black skin, never burns.
The natural shielding from harmful UV radiation is a tangible advantage of natural skin tanning. Moreover, for many decades a “healthy” skin color has been a sign of, in particular, sporting activity and is therefore considered to be desirable by a broad section of consumers. Representatives of skin types I and II who wish to enjoy such a skin shade in any case therefore have to rely on self-tanning preparations. However, representatives of skin type IIII who do not wish to excessively be exposed to the risks of sunbathing but nevertheless want to appear tanned are also thankful target groups for self-tanning preparations.
Artificial skin tanning can be brought about in a cosmetic or medicinal way, the following approaches essentially playing a role:
The regular taking of carotene preparations results in carotene being stored in the subcutaneous fatty tissue, and the skin gradually turns orange to yellow-brown.
Using make-up preparations which can be washed off it is possible to achieve a slight skin shading (e.g. extracts of fresh green walnut shells, henna).
Coloring can also take place via the route of a chemical change in the horny layer of the skin using self-tanning preparations. The most important active ingredient is dihydroxyacetone (DHA). The skin tanning achieved in this way cannot be washed off and is removed only with the normal flaking of the skin (after about 10-15 days). Dihydroxyacetone can be referred to as ketotriose and reacts as a reducing sugar with the amino acids of the skin and the free amino and imino groups of keratin via a number of intermediates in the sense of a Maillard reaction to give brown-colored substances, so-called melanoids, which are sometimes also called melanoidins.
A disadvantage of tanning with dihydroxyacetone is that the skin tanned therewith is not protected from sunburn, in contrast to “sun-tanned” skin.
A further disadvantage of dihydroxyacetone is that, particularly under the influence of ultraviolet radiation, formaldehyde is eliminated, albeit in small amounts in most cases. There was therefore an urgent need to find ways in which the decomposition of dihydroxyacetone can be effectively countered.
To overcome the disadvantages of the prior art was therefore the object of the present invention.
It was therefore surprising and could not have been foreseen by the person skilled in the art that the use of catechins or gallic esters of catechins or aqueous or organic extracts from plants or parts of plants which have a content of catechins or gallic esters of catechins, for example the leaves of the Theaceae plant family, in particular of the species Camellia sinensis (green tea) or typical ingredients thereof (such as e.g. polyphenols or catechins, caffeine, vitamins, sugars, minerals, amino acids, lipids) for intensifying natural skin tanning or for stimulating melanogenesis in human skin would overcome the disadvantages of the prior art.
Catechins are a group of compounds which are to be regarded as hydrated flavones or anthocyanidines. The catechins form the base substance of a series of natural oligo- or polymeric tannins, e.g. in tea. They occur together with other phenols in many types of fruit and are involved in the browning, catalyzed by phenol oxidases, of areas which have been subjected to pressure or have been cut (e.g. in the case of apples).
The base substance “catechin” (catechol, 3,3′,4′,5,7-flavanpentol, 2-(3,4-dihydroxy-phenyl)chroman-3,5,7-triol) is widespread in plants and occurs, for example, in the catechu. It is characterized by the structural formula
Epicatechin ((2R,3R)-3,3′,4′,5,7-flavanpentol) is an epimer of catechin and is characterized by the structural formula
The objects according to the invention are likewise achieved by cosmetic or dermatological preparations comprising vegetable extracts having a content of catechins, in particular those preparations which comprise green tea extracts
Max Heiner
Schönrock Uwe
Beiersdorf AG
Dees Jose′ G.
Lamm Marina
Norris & McLaughlin & Marcus
LandOfFree
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