Isoprostane

The isoprostanes are prostaglandin-like compounds formed in vivo from the free radical-catalyzed peroxidation of essential fatty acids (primarily arachidonic acid) without the direct action of cyclooxygenase (COX) enzyme. These nonclassical eicosanoids possess potent biological activity as inflammatory mediators that augment the perception of pain. These compounds are accurate markers of lipid peroxidation in both animal and human models of oxidative stress.

Abundance
Polyunsaturated fatty acids other than arachidonic acid are also vulnerable to reactive oxygen species and produce isoprostanes. For example, in addition to the four classes of F2-isoprostanes that can arise from arachidonic acid, peroxidation of eicosapentaenoic acid (EPA) is predicted to lead to the generation of six classes of F3 isoprostanes, &alpha;-linolenic and &gamma;-linolenic acids to two classes of E1- and F1-isoprostanes, and docosahexaenoic acid to eight classes of D4-isoprostanes and eight classes of E4-isoprostanes. Each of the classes comprise up to eight racemic isomers, leading to an astounding number of isoprostane molecules!