ascorbate-2-phosphate and Cataract

In developing chick embryos, hydrocortisone induces cataract formation following a decrease in lens glutathione content but an increase in lipid peroxide content in lens, blood and liver. The preventive effects of ascorbic acid 2-O-alpha-glucoside (AA-2G) on these parameters were compared on cataract formation with those of ascorbic acid (AsA) and ascorbic acid 2-O-phosphate (AA-2P). In these tissues, AA-2G inhibited a decrease in glutathione content and an increase in lipid peroxide content more effectively than either AsA or AA-2P. Various tissues including lens and liver have alpha-glucosidase activity, strongly suggesting that AsA is enzymatically liberated from AA-2G in these tissues. In summary, these results suggest that AA-2G exerts a potent anti-cataract activity via a reduction in oxidative damage through AsA release.

Topics: alpha-Glucosidases; Animals; Ascorbic Acid; Cataract; Chick Embryo; Glutathione; Hydrocortisone; Lens, Crystalline; Lipid Peroxides; Liver

The effect of ascorbic acid 2-O-alpha-glucoside (AA-2G) on hydrocortisone (HC)-induced lens opacity in developing chick embryo was examined and compared with those of ascorbic acid (AsA) and ascorbic acid 2-phosphate (AA-2P). The opacity was dose-dependently inhibited by a single administration of 10 or 20 mumol/egg of AA-2G and by three repeated administrations of 1, 3 or 10 mumol/egg of AA-2G. AA-2G was the most effective among the three compounds. Glucose did not enhance the preventive effect of AsA against HC-induced opacity, and neither dehydro ascorbic acid nor glucose also prevented HC-induced cataract. In the histological study, we observed many small vacuoles in the nuclear region of the opaque lens treated with HC. AA-2G inhibited the formation of such vacuoles, an effect closely correlated with the prevention of cataract formation.

Topics: Animals; Ascorbic Acid; Cataract; Chick Embryo; Dose-Response Relationship, Drug; Hydrocortisone; Lens, Crystalline; Vacuoles