The Role of Ascorbic Acid in Senile Cataract

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 82; no. 21; pp. 7193 - 7196
• Main Authors: Bensch, Klaus G., Fleming, James E., Lohmann, Wolfgang
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.11.1985; National Acad Sciences
• 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; Human; Cataract; Ascorbic acid; Ageing; Molecular interaction; In vitro; Mechanism; Proteins; Opacification; Investigation method; Lens; Oxidation; Elderly
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.82.21.7193

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.