Characterization of LY231617 protection against hydrogen peroxide toxicity

The compound LY231617 {2,6-bis(1,1-dimethylethyl)-4-[[(1- ethyl)amino]methy l]phenol hydrochloride} has been reported to afford significant neuroprotec tion against hydrogen peroxide (H2O2)-induced toxicity in vitro and global ischemia in vivo. We now report on further mechanistic studies of H2O2 toxi city and protection by LY231617. Brief exposure to H2O2 (15 min) elicited a n oxidative insult comparable with that generated by overnight treatment. H 2O2-mediated cellular degeneration was characterized using lactate dehydrog enase (LDH) release, changes in total glutathione, and a new marker of oxid ative stress, 8-epiprostaglandin F-2 alpha (8-isoprostane). LY231617 attenu ated H2O2-mediated degeneration under a variety of exposure conditions, inc luding a more clinically relevant posttreatment paradigm. Levels of 8-isopr ostane paralleled LDH release under various treatment paradigms of 100 mu M H2O2 +/- 5 mu M drug. In contrast, despite affording significant protectio n, LY231617 had modest to no effects on cellular levels of glutathione. Tak en together, these results are consistent with a membrane site of action fo r LY231617 and suggest that the compound affords cytoprotection via its ant ioxidant properties.