Abstract
Deleterious effect mediated by glucose degradation, as a parallel pathway to Maillard reaction, was analyzed in terms of the feasibility of inducing photo-crosslinking in isolated bovine crystalline proteins when exposed to ultraviolet A (UVA)-visible light. These experiments showed evidence supporting the generation of a glucose-derived chromophore (GDC). The ability of this chromophore to induce oxidative damage in lens protein and bovine lens epithelial cells (BLEC) was further assessed. The analysis of dityrosine and carbonyl levels in lens proteins irradiated at 5 and 20% O 2 indicates the occurrence of mixed type I/type II photosensitizing mechanisms. When BLEC were exposed to photosensitized reactions induced by GDC a decrease in cellular viability and intracellular reduced (GSH) and oxidized (GSSG) glutathione ratio was observed, as well as an increase in the amount of intracellular reactive oxygen species. Our data suggest a major effect of type I photosensitizing mechanism in both lens proteins photo-oxidation and oxidative stress induced in BLEC.
Highlights
Cataract is one of the main causes of blindness worldwide and currently it has been proposed to play a role in systemic health through disruption of the circadian biological clock.[1,2] Sunlight has been established as a risk factor for nuclear and cortical cataract diseases.[3,4,5] In the same sense, the effect of the cumulative light-exposure from the modern and widely used white light-emitting diodes (LED) as a source of potential oxidative risk to Oxidative Modifications in Crystallin Proteins and Lens Epithelial CellsJ
In this work we have studied the generation of chromophores from glucose and the photosensitizing capacity of the major chromophore arising from its degradation, in terms of the effects of the photosensitizing mechanism in oxidative chemical modifications in bovine lens proteins and epithelial cells
For this reason we conducted experiments aimed to determining the contribution of photosensitized reactions mediated by AGEs derived from glucose, in a model where bovine eye lens proteins were incubated with this monosaccharide in the presence and absence of permanent exposure to ultraviolet A (UVA)‐visible light
Summary
Cataract is one of the main causes of blindness worldwide and currently it has been proposed to play a role in systemic health through disruption of the circadian biological clock.[1,2] Sunlight has been established as a risk factor for nuclear and cortical cataract diseases.[3,4,5] In the same sense, the effect of the cumulative light-exposure from the modern and widely used white light-emitting diodes (LED) as a source of potential oxidative risk to Oxidative Modifications in Crystallin Proteins and Lens Epithelial CellsJ. When bovine lens proteins were incubated during the same time period in the absence of glucose and exposed to UVA-Visible light, no significant modifications in the SDS‐PAGEs profiles were observed (data not shown).
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