Oxygen-free radicals may injure the epithelium of corneas in storage awaiting transplantation. This study compared the cytoprotective effects of several antioxidants against oxygen-free radical injury to rabbit corneal epithelial cells in vitro. Cultured rabbit corneal epithelial cells were exposed to oxygen-free radicals generated by xanthine oxidase and hypoxanthine. The cytoprotective activities of various antioxidants on this system were compared using established morphologic criteria. The results demonstrated that purpurogallin at 1.0 mM delayed cell necrosis to 9.98 +/- 1.16 min compared with 2.96 +/- 0.67 min without antioxidant protection. This degree of protection was significantly different from that provided by ascorbate (1.0 mM), trolox (1.0 mM), superoxide dismutase + catalase, catalase (92,000 IU/L), mannitol (1.0 mM), and superoxide dismutase (24,200 IU/L) (p < 0.01). We concluded that purpurogallin effectively protects corneal epithelium from oxygen-free radical injury and may help prevent such injury in corneal preservation solutions.