A nomenclature system for the isoprostanes

In 1990, prostaglandin (PG) F₂-like compounds were discovered to be produced in abundance in vivo by a free radical mechanism independent of the cyclooxygenase enzyme. Because these compounds are isomeric to cyclooxygenase-derived PGF_2α, they were termed F₂-isoprostanes (F₂-ISOP's). Subsequently, it was also demonstrated that PGD₂-like compounds (D₂-IsoP'S) and PGE₂-like compounds (E₂-IsoP's) are also produced in vivo as products of this pathway. Four different regioisomers of each of these classes of ISOP'S are formed, each of which can be comprised of eight racemic diastereomers. Thus, 64 different F₂-IsoP's, E₂-IsoP's, and D₂-IsoP's can be formed. Interest in these molecules stems not only from the fact that quantification of IsoP'S can provide a valuable index of free radical-induced lipid peroxidation in vivo but also from the fact that it has been shown that these compounds are capable of exerting potent biological activity. Because of this potential for exerting biological activity, the chemical syntheses of various IsoP compounds for biological testing has been initiated. As a result, a need for a systematic nomenclature for these compounds has evolved. A facile nomenclature that will allow rational differentiation and designation of each of the isomeric structures comprising the family of IsoP'S is presented.