title: Nitrite-induced photo-oxidation of thiol and its implications in smog toxicity to the eye: prevention by ascorbate.
abstract: Studies have been conducted on nitrite-induced oxidation of corneal thiols and reduced glutathione (GSH). Oxidation of GSH in the presence of nitrite (NaNO2) was minimal in the dark. Exposure of GSH to UV (365 nm) in the presence of nitrite substantially accelerated this oxidation; only < 10% of the original GSH remained at the end of 20 minutes. A similar Thiol depletion was observed in the case of corneal epithelial extracts irradiated with UV in the presence of the nitrite. Nitrite is therefore considered to be a potent phototoxicant with possible pathophysiological implications to the external eye tissues. Ascorbate was found to be effective in preventing thiol oxidation, suggesting the possibility of preventing nitrogen oxide-based smog irritation to the eye by this physiologically compatible antioxidant.
authors.affiliation: Department of Ophthalmology, University of Maryland School of Medicine, Baltimore, USA.
authors.forename: S D
authors.initials: SD
authors.lastname: Varma
authors.forename: A H
authors.initials: AH
authors.lastname: Ali
authors.forename: P S
authors.initials: PS
authors.lastname: Devamanoharan
authors.forename: S M
authors.initials: SM
authors.lastname: Morris
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology* / Q000627:therapeutic use; D002417:Cattle; D003315:Cornea / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D004492:Edetic Acid / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism*; D066298:In Vitro Techniques; D010083:Oxidants, Photochemical / Q000494:pharmacology / Q000633:toxicity*; D010084:Oxidation-Reduction / Q000187:drug effects / Q000528:radiation effects; D012905:Smog / Q000009:adverse effects*; D012977:Sodium Nitrite / Q000494:pharmacology / Q000528:radiation effects / Q000633:toxicity*; D014466:Ultraviolet Rays
chemical_list: D016166:Free Radical Scavengers; D010083:Oxidants, Photochemical; D012905:Smog; D004492:Edetic Acid; D005978:Glutathione; D012977:Sodium Nitrite; D001205:Ascorbic Acid