Fatty acids biomarker molecules

The isoprostanes are a unique series of prostaglandin-like compounds formed in vivo via a nonenzymatic mechanism involving the free radical-initiated peroxidation of arachidonic acid. This article summarizes our current knowledge of these compounds. Herein, a historical account of their discovery and the mechanism of their formation are described. Methods by which these compounds can be analyzed and quantified are also discussed, and the use of these molecules as biomarkers of in vivo oxidant stress is summarized. In addition to being accurate indices of lipid peroxidation, some isoprostanes possess potent biological activity. This activity will be discussed in detail. Finally, in more recent years, isoprostane-like compounds have been shown to be formed from polyunsaturated fatty acids, including eicosapentaenoic acid and docosahexaenoic acid. These findings will be summarized as well. 

Compound-specific A C values for 31 different lipid biomarker molecules are shown in Figure 8 for sedimentary horizons corresponding to pre-bomb (before ad 1950) and post-bomb (1950-1996) eras. These organic compounds represent phytoplank-tonic, zooplanktonic, bacterial, archaeal, terrestrial higher plant, and fossil carbon sources. The lipid classes include long-chain n-alkanes, alkanoic (fatty) acids, -alcohols, C30 mid-chain ketols and diols, sterols, hopanols, and C40 isoprenoid side chains of the ether-linked glycerols of the Archaea. 

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