8-isoProstaglandin F2α (8-isoPGF2α; 8-isoprostane) is a byproduct of non-specific lipid peroxidation, resembling prostaglandin in structure. In humans and rats, its metabolite, 12,3-dinor-8-isoPGF2α, is formed following exogenous administration of 8-isoPGF2α, which is converted to 2,3-dinor-8-isoPGF1α and 2,3-dinor-8-isoPGF2α. Additionally, rat hepatocytes can further break down 8-isoPGF2α into a β-oxidation product, 2,3,4,5-tetranor-8-isoPGF2α. The metabolite, 2,3-dinor-8-isoPGF2α, is normally found in human urine at concentrations of 200-300 pg ml. Its levels rise in conditions associated with oxidative stress, such as smoking, demonstrating a correlation with the concentration of its precursor, 8-isoPGF2α.
8-isoProstaglandin F2β (8-iso PGF2β) is an isomer of PGF2α of non-enzymatic origin. It is one of 64 possible isomers of PGF2α which can be produced by free radical peroxidation of arachidonic acid. 8-iso PGF2β exhibits very weak contraction of human umbilical vein artery and does not promote aggregation of human whole blood. However, 8-iso PGF2β moderately contracts both the canine and porcine pulmonary vein, although the effect is much weaker than that exhibited by other isoprostanes such as 8-iso PGE1, 8-iso PGE2, or 8-iso PGF2α. 8-iso-15-keto PGF2β is a potential metabolite of 8-iso PGF2β via the 15-hydroxy PG dehydrogenase pathway. There are no published reports on the formation or biological activity of 8-iso-15-keto PGF2β.