Protective Effect of Morin Hydrate on Reactive Oxygen Injury in Rabbit Corneal Epithelium

ABSTRACT

PURPOSE: Free radicals are responsible for tissue injury in corneal preservation and transplantation. Morin hydrate, a flavonoid from Brazil wood, has been shown to be cytoprotective in several types of cells. The aim of this study was to investigate the effectiveness of morin hydrate on rabbit cornea against damage induced by oxyradicals and nitric oxide. METHODS: The rabbit cornea was studied in modified Ussing chambers to determine the effects of hydrogen peroxide (H2O2) or sodium nitroprusside (SNP) by measuring the bioelectrical properties (short-circuit current (Isc), tissue resistance (Rt) and potential difference (PD)). RESULTS: 1.0 mM H2O2 markedly increased the Isc at the tear side (T-side), but not at stromal side (S-side), suggesting the site of action of H2O2 was the apical membrane (T-side). After pretreatment with morin hydrate (T-side, 1.0 mM), H2O2-induced increase of Isc and PD was markedly reduced. In addition adding morin hydrate with H2O2 simultaneously, the increase of Isc and PD was also markedly reduced. Exposure of cornea to SNP at the T-side increased nitric oxide, and increased the bioelectrical properties (PD and Isc). This effect was attenuated by the treatment with morin hydrate. CONCLUSIONS: This study demonstrated that morin hydrate behaved as a antioxidant. This property of morin hydrate may help prevent protect cornea in preservative solutions from free radical damage.