Prevention of selenite-induced cataractogenesis in Wistar rats by the polyphenol, ellagic acid.

The present study sought to evaluate the efficacy of the naturally-occurring polyphenol, ellagic acid, in preventing selenite-induced cataractogenesis. In the present study, Wistar rat pups were divided into 3 groups of 15 each. Group I (normal) rats received an intraperitoneal (i.p.) injection of normal saline on postpartum day 10; group II (cataract-untreated) rats received a single subcutaneous (s.c.) injection of sodium selenite (19 micromol/kg body weight) on postpartum day 10; group III (cataract-treated) pups received a single s.c. injection of sodium selenite on postpartum day 10 and intraperitoneal injections of ellagic acid (200mg/kg body weight) on postpartum days 9-14. At the end of the study period (30th postpartum day), slit-lamp examination of both eyes of each rat pup revealed no lenticular opacification (cataract stage 0) in all eyes of group I pups, definite nuclear cataracts (stages 4-6) in the eyes of all (100%) group II rat pups and no lenticular opacification in eight (53%) and mild lenticular opacification (cataract stages 1-3) in seven (47%) of group III rats (changes in group II vs group III, P<0.01). The mean activities of the antioxidant enzymes catalase, glutathione peroxidase, superoxide dismutase and glutathione-S-transferase were significantly lower in lenses of Group II rats than in Group I or Group III rat lenses. In addition, the mean levels of GSH in lenses and erythrocytes were also significantly lower in Group II rats than in Group I or Group III rats. Conversely, the mean concentration of MDA (an indicator of lipid peroxidation) in lenses and erythrocytes was found to be significantly higher in Group II rats than that in Group I or Group III rats. Also, the mean concentration of calcium was found to be significantly higher in lenses of Group II rats than in those of Group I and Group III rats. The results suggest that ellagic acid can prevent or retard experimental selenite-induced cataractogenesis in Wistar rats. This protective effect in rat lenses appears to occur by maintaining the antioxidant defense system and inhibition of lipid peroxidation.