title: Lipofuscins prepared by modification of photoreceptor cellsviaglycation or lipid peroxidation show the similar phototoxicity.
abstract: OBJECTIVE
  To investigate the effect of two ways of lipofuscin production (lipid peroxidation and glycation) on lipofuscin fluorescence characteristics and phototoxicity and to compare them with the properties of natural lipofuscin.
  
  
  METHODS
  Model lipofuscins were prepared on the basis of bovine photoreceptor outer segments (POS) with bisretinoid A2E addition. One set of samples was prepared from POS modified by lipid peroxidation, while another set from POS modified by glycation with fructose. Fluorescent properties and kinetics of photoinduced superoxide generation of model lipofuscins and human retinal pigment epithelium (RPE) lipofuscin were compared. The fluorescence spectra of samples were measured at 365 nm excitation wavelength and 380-650 emission wavelength.
  
  
  RESULTS
  The fluorescence spectra of model lipofuscins are almost the same as the spectrum of natural lipofuscin. Visible light irradiation of both model lipofuscins and natural lipofuscin isolated from RPE cells leads to decrease of a fluorescence maximum at 550 nm and to appearance of a distinct, new maximum at 445-460 nm. The rate of photogeneration of reactive oxygen forms by both model lipofuscins was almost the same and approximately two times less than that of RPE lipofuscin granules.
  
  
  CONCLUSIONS
  These data suggest that fluorescent characteristics and phototoxicity of lipofuscin granules depend only to an insignificant degree on the oxidative modification of POS proteins and lipids, and generally are defined by the bisretinoid fluorophores contained in them.
authors.affiliation: Alexander Dontsov, Anna Koromyslova, Mikhail Ostrovsky, Natalia Sakina, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Dontsov
authors.affiliation: Alexander Dontsov, Anna Koromyslova, Mikhail Ostrovsky, Natalia Sakina, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia.
authors.forename: Anna
authors.initials: A
authors.lastname: Koromyslova
authors.affiliation: Alexander Dontsov, Anna Koromyslova, Mikhail Ostrovsky, Natalia Sakina, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Ostrovsky
authors.affiliation: Alexander Dontsov, Anna Koromyslova, Mikhail Ostrovsky, Natalia Sakina, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia.
authors.forename: Natalia
authors.initials: N
authors.lastname: Sakina
keywords: Bisretinoids; Glycation; Lipid peroxidation; Model lipofuscins; Photoreceptor outer segments; Retinal pigment epithelium; Superoxide