F-2 isoprostanes, potential specific markers of oxidative damage in human retina

F-2 isoprostanes (F-2-IPs) are a series of prostaglandin-F-2(PGF(2))-like c ompounds produced during peroxidation of arachidonic acid (AA) by a mechani sm independent of the cyclo-oxygenase. Of these, 8-epi-PGF(2 alpha) has pro ved a reliable marker of oxidative stress in studies both in vitro and in v ivo, Human retinas (n = 28) were obtained from healthy donors (age 15-59 ye ars) and analysed for the content of free (non-esterified) as well as total (sum of free and esterified) F-2-IPs. Retina tissue was homogenised, total lipids were partitioned with ethyl acetate and isoprostanes were isolated by chromatography on an NH2 cartridge. After formation of pentafluorobenzyl ester and trimethylsilyl derivatives, F-2-IPs were analysed by negative io n-chemical ionisation mass spectrometry using tetradeuterated PGF(2 alpha) as the internal standard. Analysis of retina samples revealed the presence of measurable amounts of esterified 8-epi-PGF(2 alpha) (mean: 81.71 mu g/g AA; range: 3.29-187.89 mu g/g AA) but not free F-2-IPs. There was no correl ation between age and content of 8-epi-PGF(2 alpha). Detection of esterifie d F-2-IPs in human retina provides the first direct evidence for free-radic al-catalysed peroxidation of AA in retinal tissue. Analysis of F-2- IPs sho uld provide new opportunities for studying the implications of oxidative in jury in various diseases of retina, including diabetic retinopathy and age- related macular degeneration, Copyright (C) 2000 S. Karger AG. Basel.