Effects of water extract of 1:1 mixture of Phellodendron cortex and Aralia cortex on polyol pathway and oxidative damage in lenses of diabetic rats.

Enhanced activity of the polyol pathway and oxidative damage have been implicated in the pathogenesis of diabetic cataract. We decided to investigate whether these changes in diabetic lenses could be prevented by the water extract of Phellodendron cortex and Aralia cortex (P55A). Aldose reductase activity was inhibited significantly by the treatment with P55A. Consequently, it caused a dramatic reduction in the high sorbitol contents observed in the lenses of diabetic rats. In addition, the greatly elevated content of thiobarbituric acid reactive substances (TBARS) and carbonylated protein in diabetic rats were reduced by P55A treatment. These results suggest that P55A extract exerts an antioxidant effect by reducing lipid peroxidation and protein carbonylation as well as having an inhibitory action against aldose reductase in the lenses of diabetic rats.