The isoprostanes are

prostaglandin The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derive ...

-like compounds formed ''in vivo'' from the free radical-catalyzed

peroxidation Lipid peroxidation is the chain of reactions of oxidative degradation of lipids. It is the process in which free radicals "steal" electrons from the lipids in cell membranes, resulting in cell damage. This process proceeds by a free radical chai ...

essential fatty acid Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them. Only two fatty acids are known to be essential for humans: alpha-linolenic ac ...

s (primarily

arachidonic acid Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6), or 20:4(5,8,11,14). It is structurally related to the saturated arachidic acid found in cupuaçu butter. Its name derives from the New Latin word ''arachi ...

) without the direct action of

cyclooxygenase Cyclooxygenase (COX), officially known as prostaglandin-endoperoxide synthase (PTGS), is an enzyme (specifically, a family of isozymes, ) that is responsible for formation of prostanoids, including thromboxane and prostaglandins such as prosta ...

(COX) enzymes. The compounds were discovered in 1990 by L. Jackson Roberts and Jason D. Morrow in the Division of Clinical Pharmacology at Vanderbilt University. These

nonclassical eicosanoid Nonclassic eicosanoids are biologically active signaling molecules made by oxygenation of twenty-carbon fatty acids other than the classic eicosanoids. Terminology : "Eicosanoid" is the collective term for oxygenated derivatives of three differ ...

s possess potent

biological activity In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...

as inflammatory mediators that augment the perception of

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

. These compounds are accurate markers of

lipid peroxidation Lipid peroxidation is the chain of reactions of oxidative degradation of lipids. It is the process in which radical (chemistry), free radicals "steal" electrons from the lipids in cell membranes, resulting in cell damage. This process proceeds by ...

in both animal and human models of

oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily Detoxification, detoxify the reactive intermediates or to repair the resulting damage. Disturbances ...

. Elevated levels of isoprostanes are suspected of contributing to increased risk of heart attack in patients taking

Coxibs COX-2 inhibitors are a type of nonsteroidal anti-inflammatory drug (NSAID) that directly targets cyclooxygenase-2, COX-2, an enzyme responsible for inflammation and pain. Targeting selectivity for COX-2 reduces the risk of peptic ulceration and ...

. Isoprostanes and their metabolites have also been shown to be elevated in the urine of cigarette smokers, and have been suggested as biomarkers of oxidative stress in smokers.

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

, peroxidation of

eicosapentaenoic acid Eicosapentaenoic acid (EPA; also icosapentaenoic acid) is an omega-3 fatty acid. In physiological literature, it is given the name 20:5(n-3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid with a 20-c ...

(EPA) is predicted to lead to the generation of six classes of F3 isoprostanes, α-linolenic and γ-linolenic acids to two classes of E1- and F1-isoprostanes, and

docosahexaenoic acid Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. In physiological literature, it is given the name 22:6(n-3). It can be synthesized from alpha-lino ...

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.{{cite journal , author=Janssen LJ , title=Isoprostanes: an overview and putative roles in pulmonary pathophysiology , journal=Am. J. Physiol. Lung Cell Mol. Physiol. , volume=280 , issue=6 , url=http://ajplung.physiology.org/cgi/reprint/280/6/L1067 , pages=L1067–82 , year=2001 , pmid=11350785 , doi=10.1152/ajplung.2001.280.6.L1067 , access-date=2007-11-02

References

Prostaglandins

Abundance

See also

References