title: Role of iron in the photosensitization by uroporphyrin.
abstract: The role of iron in the mechanism of photosensitivity due to uroporphyrin was investigated. There is frequently increased levels of Fe in the serum from patients with porphyria cutanea tarda, where the photosensitivity is due to uroporphyrin. It has been reported that H2O2 has a major role in the uroporphyrin induced photosensitivity. Hence we examined the hypothesis that Fe would catalyze the production of OH from H2O2 and the OH thus formed may have a significant role in the uroporphyrin photosensitivity. This was examined by studying the effects of the Fe chelating compound deferoxamine in an in vitro system. Our results show that deferoxamine inhibited the uroporphyrin photosensitivity, but not the photosensitivity due to protoporphyrin. This indicates that Fe may play a role in the uroporphyrin photosensitization in the skin, by accelerating the formation of OH, which may be a major reactive species responsible for the photosensitization in porphyria cutanea tarda.
authors.affiliation: Department of Medicine and Ophthalmology, University of Toronto, ON, Canada.
authors.forename: I A
authors.initials: IA
authors.lastname: Menon
authors.forename: M A
authors.initials: MA
authors.lastname: Becker
authors.forename: H F
authors.initials: HF
authors.lastname: Haberman
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor; D002470:Cell Survival / Q000187:drug effects* / Q000528:radiation effects; D002860:Chromium Radioisotopes; D003624:Darkness; D003676:Deferoxamine / Q000494:pharmacology*; D007501:Iron / Q000378:metabolism*; D008027:Light; D051379:Mice; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014578:Uroporphyrins / Q000494:pharmacology*
chemical_list: D002860:Chromium Radioisotopes; D011838:Radiation-Sensitizing Agents; D014578:Uroporphyrins; D007501:Iron; D003676:Deferoxamine