HPLC Analysis of Lipid-derived Polyunsaturated Fatty Acid Peroxidation Products in Oxidatively Modified Human Plasma

Abstract

Lipid peroxidation is a prominent manifestation of free radical activity and oxidative stress in biological systems. Diverse methodologies have been developed that measure a variety of lipid peroxidation products used as markers of lipid peroxidation processes. Hydroxy and hydroperoxy polyunsaturated fatty acid (PUFA) peroxidation products were analyzed in human blood plasma by reversed-phase HPLC after liquid-liquid extraction of total lipids and alkaline hydrolysis of lipid esters to liberate free PUFAs. An isocratic mobile phase containing 1 g/L acetic acid-acetonitrile-tetrahydrofuran (52:30:18, by volume) over 60 min duration, with ultraviolet absorbance detection at 236 nm by photodiode array, enabled the resolution and quantification of 13 regioisomeric hydroxy and hydroperoxy PUFAs. As little as 250 microL of human plasma was utilized with an analytical range of 0.033-1.6 micromol/L for each compound. Intra- and interassay CVs for all compounds detected in normal or oxidatively modified human plasma were 3.2-11% and 4.7-12%, respectively. Analytical recoveries were 87-103%. Analysis of human plasma exposed to artificial oxidation with Cu(2+) ion and hydrogen peroxide, a free radical-generating reaction, showed marked increases in hydroxy and hydroperoxy PUFA concentrations. Lipid-derived hydroxy and hydroperoxy PUFAs may be useful as clinical markers of lipid peroxidation and oxidative stress in the peripheral circulation.