The Effect of Pinitol on Cataractogenesis and Anti-oxidative effect in Streptozotocin Induced Diabetic Rats

ABSTRACT

PURPOSE: Pinitol, a natural extract of soybeans, is metabolized to chiroinositol in the body. We evaluated the ability of pinitol to protect diabetic cataracts from oxidative stress in streptozotocin (STZ)-induced diabetic rats. METHODS: We used Sprague-Dawley rats (n=80). Diabetes was induced with STZ (60 mg/kg, i.p.). These STZ-injected rats were administered pinitol or chiroinositol, each 20 mg/ml, and given access to regular chow. The efficacies of pinitol and chiroinositol were studied by monitoring a series of lens opacity and corneal lesion by photodocumentation. Aqueous humor and lens samples were collected at the 2nd week, 4th week, and 12th week. We measured glutathione, malondialdehyde (MDA) and used ELISA to evaluate its antioxidant effect. RESULTS: STZ-diabetic rats showed typical Y sutural lens opacity beginning on the 3rd day and progressed diffusely to more cortical opacity from the 1st week. However, in pinitol-treated diabetic rats, these cataractous changes were remarkably decreased. Corneal edema and opacity also remarkably reduced in the pinitol-treated group. Glutathione level markedly increased compared to that of the non-treated diabetic group (230.12+/-10.96 micrometer, 156.42+/-5.09 micrometer, respectively). This resulted in a decrease in peroxidized MDA product in the treated group. Similarly, the anti-cataractogenic and anti-oxidative effects of pinitol were also observed in the chiroinositol-treated group. CONCLUSIONS: These results suggest that pinitol could be effective in preventing cataract and cornea edema caused by oxidative stress in a hyperglycemic environment.