NEAR UV-INDUCED FREE RADICALS IN OCULAR LENS, STUDIED BY ESR AND SPIN TRAPPING |
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| Authors: | JUNKO MURAKAMI MASAHARU OKAZAKI TAKESHI SHIGA |
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| Institution: | Department of Physiology. School of Medicine, Ehime University, Shigenobu, Onsen-gun, Ehime, 791–02, Japan;Department of Radiation Chemistry, Governmental Industrial Research Institute, Nagoya, Hirate, Kita-ku, Nagoya, 462, Japan |
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| Abstract: | 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. |
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