Quercitrin gallate inhibits aldose reductase activity and xylose-induced lens opacity and oxidation

In this study, the inhibitory effects of quercitrin gallate (QG), a polyphenolic compound, were investigated on aldose reductase (AR) activity as well as on antioxidant levels and enzyme activity in the lens. The effects of QG on xylose-induced lens opacity (cataracts), as seen in diabetes, were also examined. QG showed potential inhibitory activity against rat lens AR activity with an IC50 value of 0.064 μM. The xylose-induced opacity of the lens was significantly improved after treatment with QG. Exposure of rat lenses to xylose significantly increased the oxidized glutathione/reduced glutathione ratio, and treatment with QG significantly decreased this ratio. Antioxidant enzyme (i.e., superoxide dismutase and catalase) activities were significantly decreased under high xylose conditions, and treatment with QG significantly increased the activities and levels of these factors. These results suggest that QG may provide a potential therapeutic approach for the prevention of diabetic complications, such as cataracts.