Ornithine decarboxylase induction in psoralen-treated mouse epidermis used as a test of UV-A sunscreen potency.
Inhibition by sunscreens of UV-A-induced epidermal ornithine decarboxylase (ODC) activity in 8-methoxypsoralen-treated mice was used to examine the UV-A sunscreen activity of two commercial preparations, Uval (para-aminobenzoic acid) and PreSun (a benzophenone derivative). Both gave significant protection against UV-A doses of up to 3 J/cm2 and Uval was more effective that PreSun in the UV-A range. At intermediate doses (5-15 J/cm2) neither Uval nor PreSun significantly altered the ODC response to UV-A. At doses of 20-40 J/cm2 UV-A, control and PreSun-treated animals showed a decline in ODC activity which histological studies suggested was due to severe epidermal damage. This decline in ODC activity and severe epidermal damage was not seen in Uval-treated animals. Topical zinc oxide was highly effective in preventing induction of ODC by UV-A irradiation at doses up to 40 J/cm2, and was significantly more effective than either PreSun or Uval.
D010129:4-Aminobenzoic Acid / Q000494:pharmacology; D000818:Animals; D001577:Benzophenones / Q000494:pharmacology; D002262:Carboxy-Lyases / Q000096:biosynthesis*; D004307:Dose-Response Relationship, Radiation; D004790:Enzyme Induction / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D008730:Methoxsalen / Q000494:pharmacology; D051379:Mice; D008812:Mice, Hairless; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D012867:Skin / Q000201:enzymology*; D013473:Sunscreening Agents; D013997:Time Factors; D014466:Ultraviolet Rays; D015034:Zinc Oxide / Q000494:pharmacology
D001577:Benzophenones; D013473:Sunscreening Agents; C005290:oxybenzone; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; D015034:Zinc Oxide; D010129:4-Aminobenzoic Acid; D008730:Methoxsalen