Enzyme Immunoassay of Isoprostanes

Isoprostanes are a group of prostaglandin-like compounds that are derived in vivo primarily by free radical-mediated peroxidation of arachidonic acid within phospholipids. The resulting isoprostane moieties are rapidly hydrolyzed, metabolized, and excreted. It is now well recognized that isoprostane levels, most commonly those of 15F_2t -isoprostane (formerly denoted 8-iso-prostaglandin F_{2 α} ) in blood or urine, are useful biomarkers for the assessment of oxidative stress, which is a major risk factor for many diseases. Isoprostanes were initially quantified by GC/MS following multiple extraction and purification steps. However, to facilitate routine cost-effective analysis of these biomarkers, immunoassays for isoprostanes were developed. Given the large number of isoprostanes, isoprostane metabolites, and isoprostane conjugates in vivo, the potential for their ex vivo generation from arachidonic acid, and differences among protocols for GC/MS and immunoassay of these biomarkers, it is not surprising that discrepancies arise in values obtained using different methods. When appropriate precautions are taken during sample collection, preparation, and analysis, enzyme immunoassays for 15F_2t -isoprostane can be used for the reproducible and reliable assessment of oxidative stress in experimental animals or human subjects.