Photostabilität und Hautaffinität - zwei Kriterien für kosmetische Lichtschutzsubstanzen am Beispiel der Naphthalin-1,5-bis-harnstoffe
Udo Hoppe

Synopsis

Photostability and skin affinity — two criteria for cosmetic light protective substances, e.g. naphthalene-1,5-bisureas . — The assessment of ULTRAVIOLET LIGHT ABSORBERS for SUNSCREENING PRODUCTS includes not only practical utility and absence of toxicity, both of which play an important role, but the equally important aspects of PHOTOSTABILITY and SKIN AFFINITY. With the aid of a simple illuminator it is shown that — with or without the addition of DIHYDROXYACETONE AS A PHOTO-SENSITIZER — some light protective substances in hydroalcoholic solution show varying photostability. NEW NAPHTHALENE-1,5-BISUREAS are described which are stable and, depending on their substitution, can be used as UV-B OR UV-A ABSORBERS. Rinse tests have shown that these compounds adhere well to PIGSKIN. Furthermore, they exhibit the remarkable and unusual PROPERTY OF FORMING GELS in hydrophobic solvents.

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