The Role of Ascorbic Acid in Senile Cataract

The reductone ascorbic acid, present in the crystalline lens in concentrations higher than those of glucose, is capable of undergoing nonenzymatic ``browning'' in the presence of lenticular proteins. We studied the nonenzymatic browning with ascorbate in model systems employing bovine seru...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1985-11, Vol.82 (21), p.7193-7196
Main Authors: Bensch, Klaus G., Fleming, James E., Lohmann, Wolfgang
Format: Article
Language:English
Subjects:
Anaerobiosis
Analytical, structural and metabolic biochemistry
Animals
Antioxidants - metabolism
Ascorbic Acid - metabolism
Ascorbic Acid - toxicity
Biochemistry
Biological and medical sciences
Carbohydrate Metabolism
Cataract - chemically induced
Cataract - metabolism
Cataracts
Crystallins
Crystallins - metabolism
Essential fatty acids
Fluorescence
Free Radicals
Fundamental and applied biological sciences. Psychology
Glutathione Reductase - physiology
Humans
Mice
Miscellaneous
Oxidation
Oxidation-Reduction
Phosphates
Proteins
Radioactive decay
Serum Albumin, Bovine - metabolism
Serum albumins
Ungulates
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Summary:The reductone ascorbic acid, present in the crystalline lens in concentrations higher than those of glucose, is capable of undergoing nonenzymatic ``browning'' in the presence of lenticular proteins. We studied the nonenzymatic browning with ascorbate in model systems employing bovine serum albumin and lens crystallins. When bovine serum albumin, α -crystallin, or γ -crystallin was incubated with [14C]ascorbic acid, the formation of yellow and then brown condensation products appeared to correlate with increasing protein-associated radioactivity. The fluorescence spectrum of these products was similar to that of homogenates of human cataractous lenses. We suggest that the nonenzymatic reaction of lens crystallins with ascorbic acid may contribute, at least in part, to the color changes of aging lenses and to the physical lenticular deterioration leading to senile cataract. High dietary intake of ascorbic acid did not affect the fluorescence spectrum of murine lenses; thus, we assume that the speed and extent of the lenticular browning reactions must depend on a deterioration of other factors of the multicomponent antioxidant system of the eye.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.82.21.7193