Aldose reductase inhibitory potential and anti-cataract activity of Punica granatum Linn. leaves against glucose-induced cataractogenesis in goat eye lens

Cataract is one of the primitive secondary complications of diabetes mellitus and contributes to 50% blindness worldwide. Aldose reductase (AR) is the first and rate limiting enzyme in the intracellular polyol pathway responsible for the development of cataract. Thus, there is an imperative need for modest, non-surgical way in order to treat cataract. In Ayurveda, Punica granatum (Pomegranate) is considered as a pharmacy unto itself. Pomegranate leaves are traditionally used for their anti-diabetic activity. In this study, we investigated AR inhibitory activity and anti-cataract potential of Pomegranate leaves in glucose - induced cataract in goat lens. AR inhibitory activity was evaluated in vitro in goat lenses. In glucose induced cataract model, goat lenses were incubated in artificial aqueous humor containing 55 mM glucose along with methanolic extract of Punica granatum leaves (MPGL) or quercetin for 72 h. After 72 h, photographic evaluation of the lens was carried out and the lens antioxidant parameters were determined. Different concentrations of MPGL were found to inhibit lens AR activity with an IC50 value of 83.55 +/- 3.92 mu g/ml. Quercetin was taken as positive control which exhibited 56.461% AR inhibition at a concentration of 500 mu g/ml. Cataractous lenses exhibited marked opacity and decrease in the levels of reduced glutathione and superoxide dismutase. Treatment with MPGL and quercetin prevented the opacity and restored back the antioxidant activity. Together, Punica granatum leaves ameliorated glucose-induced cataractogenesis via AR inhibition, reduction in oxidative stress and improvement in antioxidant defense system.