MORIN HYDRATE - A BETTER PROTECTOR THAN PURPUROGALLIN OF CORNEAL ENDOTHELIAL-CELL DAMAGE-INDUCED BY XANTHINE-OXIDASE AND SIN-1

Purpose. Free radicals are responsible for tissue injury in corneal pr eservation 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 hy drate on rabbit corneal endothelial cells against damage induced by ox yradicals and nitric oxide. Methods. Corneal endothelial cell cultures were prepared from New Zealand white rabbits, using standard microcar rier technique. Two free-radical-generating systems were used-17 IU/L xanthine oxidase/1 mM hypoxanthine and 5 mM 3-morpholinosydnonimine-N- ethylcarbamide (SIN-1, a nitric oxide-donating agent). Results. Over 9 5% of cultured corneal endothelial cells necrosed within 3.6 +/- 1.5 m in after exposure to xanthine oxidase/hypoxanthine. Adding morin hydra te delayed cell necrosis to 5.8 +/- 0.3 min (0.25 mM morin hydrate), 1 3.3 +/- 5.0 min (0.5 mM), and 41.5 +/- 8.6 min (1.0 mM). Exposed to ni tric oxide generated by SIN-1, cells necrosed by 9.5 +/- 2.5 min, vers us 14.1 +/- 1.3 min (0.25 mM morin hydrate), 27.2 +/- 2.0 min (0.5 mM) , and 43.3 +/- 5.4 min (1.0 mM). Morin hydrate significantly prolonged survival of cells compared to equimolar concentrations of purpurogall in, Trolox, or ascorbate (P < 0.01). Conclusion. This study demonstrat es that morin hydrate behaves as a broad-spectrum antioxidant: it scav enges not only xanthine oxidase/hypoxanthine-generated oxyradicals, bu t also nonenzymatic, nitrogen-derived radicals, better than those abov e mentioned antioxidants. This property of morin hydrate may help prev ent free radical damage in corneal preservation solutions.