COMPARATIVE CYTOPROTECTION OF CULTURED CORNEAL ENDOTHELIAL-CELLS BY WATER-SOLUBLE ANTIOXIDANTS AGAINST FREE-RADICAL DAMAGE

We reported previously that purpurogallin (PPG) mark edly protects the cultured rabbit corneal endothelial cells (RCEC) against oxyradical d amage generated with hypoxanthine (HX) and xanthine oxidase (XO)(1). I n this study, we further compared the cytoprotective activities of PPG versus Trolox (TX, alpha-tocopherol, a water-soluble analogue of vita min E) and ascorbate (Asc) in confluent cultured RCEC with phase contr ast microscopy and confirmed by transmission electron microscopy. PPG prolonged survival of the oxyradical damaged cells longer than those w ithout PPG present (18.6 +/- 1.4 min at 1.0 mM and 11.2 +/- 1.0 min at 0.25 mM respectively vs. 7.3 +/- 0.8 min in control). At levels equim olar to PPG, TX, and Asc were less effective in delaying cell necrosis caused by HX and XO (p < 0.01). When exposed to superoxide radicals g enerated by menadione, RCEC necrosed at 29.8 +/- 1.5 min compared to P PG 47.2 +/- 1.0 min at 1.0 mM and 38.9 +/- 1.0 min at 0.25 mM. This wa s significantly different from TX and Asc at corresponding concentrati ons (p < 0.01). PPG scavenges not only HX-XO-generated oxyradicals, bu t also nonenzymatically produced superoxide radicals, more actively th an two well known antioxidants TX and Asc.