Near UV-induced free radicals in ocular lens, studied by ESR and spin trapping.
An electron spin resonance (ESR) study on UV-photolysis of human and canine lens nuclei was carried out at room temperature. (1) At least two kinds of free radical signals, a narrow signal and a broad one, were detected at around g = 2.004. The latter is similar to that observed upon irradiation of a model solution containing both tryptophan and cysteine. (2) Two spin adducts were detected upon irradiation of canine lens in the presence of a spin trapping reagent (DMPO, 5,5-dimethyl-1-pyrroline N-oxide), i.e. a spin adduct of sulphur-centered radical (most likely glutathione thiyl radical) and the protonated adduct of solvated electron (presumably due to photo-ionization of tryptophan). (3) A tentative and simplified reaction mechanism of UV-induced damage is discussed on the basis of these observations.
Murakami
J
J
Okazaki
M
M
Shiga
T
T
D000818:Animals; D004285:Dogs; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006801:Humans; D007908:Lens, Crystalline / Q000032:analysis / Q000528:radiation effects*; D010782:Photolysis; D014466:Ultraviolet Rays / Q000009:adverse effects*
D005609:Free Radicals