Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1996-06-27
1998-03-17
Gardner-Lane, Sally
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424401, 424 7051, A61K 742, A61K 700
Patent
active
057283737
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to light protection agents, in particular cosmetic and dermatological light protection agents.
The damaging effect of the ultraviolet component of solar radiation on the skin is generally known. While rays having a wavelength of less than 290 nm (the so-called UVC range) are absorbed by the ozone layer in the earth's atmosphere, rays in the range between 290 nm and 320 nm, the so-called UVB range, cause erythema, simple sunburn or even burns of greater or lesser severity.
The narrower range around 308 nm is stated as having the maximum erythema activity of sunlight.
Numerous compounds are known for protection against UVB radiation, these being 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 filter substances available for the range between about 320 nm and about 400 nm, the so-called UVA range, since its rays can also cause damage. Thus, it has been proved that UVA radiation causes damage to the elastic and collagenic fibres of connective tissue, which ages the skin prematurely, and that it is to be regarded as the cause of numerous phototoxic and photoallergic reactions. The harmful influence of UVB radiation can be intensified by UVA radiation.
DESCRIPTION OF THE PRIOR ART
Certain derivatives of dibenzoylmethane are therefore used for protection against rays in the UVA range, although the photostability of these derivatives (Int. J. Cosm. Science 10, 53 (1988)) is not adequate.
However, UV radiation can also lead to photo-chemical reactions, the photochemical reaction products then intervening in skin metabolism.
Such photochemical reaction products are chiefly free radical compounds, for example hydroxyl radicals. Undefined free radical photoproducts which are formed in the skin itself can also display uncontrolled secondary reactions because of their high reactivity. Singlet oxygen, an excited state of the oxygen molecule without free radicals, however, can also occur under UV irradiation, as can short-lived epoxides and many other compounds. Singlet oxygen is distinguished, for example, by an increased reactivity compared with the triplet oxygen usually present (free radical ground state). Nevertheless, excited, reactive (free radical) triplet states of the oxygen molecule also exist.
In order to prevent these reactions, antioxidants and/or agents which trap free radicals can additionally be incorporated into the cosmetic or dermatological formulations.
The compounds, some of which are mentioned above, which are employed as light protection agents for cosmetic and dermatological light protection formulations are distinguished by a good light protection action. However, they have the disadvantage that to date it has been difficult to incorporate them into such formulations in a satisfactory manner. Furthermore, these compounds are pure UV-absorbing agents and are unsuitable as agents which trap free radicals.
It has already been proposed to employ vitamin E, a substance having a known antioxidative action, in light protection formulations, but here also, the action achieved remains far below that hoped for.
SUMMARY OF THE INVENTION
However, it was surprising and not to be foreseen by the expert that cosmetic and dermatological light protection formulations having an active content of thiols and/or thiol derivatives remedy the disadvantages of the prior art.
It was not to be foreseen that the thiols or thiol derivatives according to the invention or the cosmetic or dermatological formulations according to the invention would better extent foreseen that the thiols or thiol derivatives according to the invention or the cosmetic or dermatological formulations according to the invention would
In particular, it was not to be predicted that the thiols or thiol derivatives according to the invention or the cosmetic or dermatological formulations according to the invention would be distinguished by a pronounced delayed
REFERENCES:
patent: 4827016 (1989-05-01), Morgan
patent: 4992267 (1991-02-01), DenBeste et al.
patent: 5208014 (1993-05-01), Dubief et al.
Alert Dirk
Beijersbergen van Henegouwen Gerard M. J.
Gers-Barlag Heinrich
Van Den Broeke Leon T.
Beiersdorf AG
Gardner-Lane Sally
Rijksuniversiteit Leiden
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