Chromatographic analysis of lipoxygenase products Review Article

Lipoxygenases (LOXs) are non-heme iron-containing enzymes, widely distributed both in the plant and animal kingdom. They catalyse the regio- and stereospecific dioxygenation of polyunsaturated fatty acids (PUFAs) which contain a (1Z,4Z)-pentadiene system. Although, most LOXs catalyze the formation of one particular regioisomer, it has become apparent that several LOXs exhibit a dual or even multiple positional specificity. Hydroperoxides, the primary products of LOX, are short-lived and are transformed into various families of metabolites. In plants, hydroperoxides are metabolized via several secondary pathways to form bioactive compounds such as jasmonates. In animals, the oxidation of arachidonic acid (AA) by LOX is the source of highly active bioregulators such as leukotrienes and lipoxins. The ability of LOX products to initiate the synthesis of different signaling molecules is determined by the positional and stereospecific nature of the hydroperoxides produced. Thus, the complete characterization of LOX products is essential for establishing the physiological role of this enzyme. Different methods to determine the positional specificity of LOX products have been proposed. In this review, we will describe the different chromatographic methods (RP-, SP- and CP-HPLC, LC/MS and GC/MS) reported to date for analyzing the regio- and stereospecificity of the primary reaction products of LOX.