Retinal pigment epithelium pigment granules stimulate the photo- oxidation of unsaturated fatty acids

Alexander E. Dontsov, Randolph D. Glickman, Mikhail A. Ostrovsky

Research output: Contribution to journalArticle

72 Scopus citations

Abstract

The cellular pigments of the retinal pigment epithelium (RPE) have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. This activity is sufficient to cause photooxidation of several major cellular components. The present investigation determined the relative ability of melanin, lipofuscin, and melanolipofuscin granules isolated from human and bovine eyes to oxidize polyunsaturated fatty acids, specifically linoleic and docosahexaenoic acids. The dark reactivity as well as the light-stimulated reactions were determined. The production of hydroperoxide derivatives of the linoleic and docosahexaenoic acids were determined by NADPH oxidation coupled to the activity of glutathione peroxidase, and also by production of thiobarbituric acid reactive substances. All RPE pigment granules stimulated fatty acid oxidation when irradiated with short wavelength (<550 nm) visible light, with the melanosomes exhibiting the greatest light-induced activity. Only lipofuscin granules, however, caused peroxidation of fatty acids in the dark. These findings provide additional support for the role of RPE pigments in 'blue light toxicity' as well as indicating that accumulation of lipofuscin may contribute to increased photooxidation in the aging RPE.

Original languageEnglish (US)
Pages (from-to)1436-1446
Number of pages11
JournalFree Radical Biology and Medicine
Volume26
Issue number11-12
DOIs
StatePublished - Jun 1 1999

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Keywords

  • Free radicals
  • Lipofuscin
  • Melanin
  • Melanolipofuscin
  • Photooxidative stress
  • Polyunsaturated fatty acids
  • Retinal degeneration
  • Retinal pigment epithelium

ASJC Scopus subject areas

  • Biochemistry
  • Physiology (medical)

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