Simultaneous Determination of Polyunsaturated Fatty Acids and Corresponding Monohydroperoxy and Monohydroxy Peroxidation Products by HPLC

Lipid peroxidation (LPO) is a prominent manifestation of free radical (FR) activity in biological systems. The primary target of FR attack on lipids is the 1,4-pentadiene structure of a polyunsaturated fatty acid (PUFA), which are either free or esterified to cholesterol or glycerol. Initiation occurs when a FR abstracts a methylene hydrogen from PUFA. In this reaction the FR is quenched and a PUFA centered alkoxyl radical (L•) is formed. L• then undergoes a spontaneous rearrangement of its double bonds forming a conjugated diene. Reaction of L• with molecular oxygen produces a PUFA-centered peroxyl radical (LOO•). Propagation occurs when either L• or LOO• act as initiating FR and attack a neighboring PUFA in a tightly packed lipid bilayer structure of a membrane or within a lipoprotein. The product of this reaction is a new L•, which can further propagate the reaction and form a lipid hydroperoxide (LHP) (1 ). Termination occurs when an antioxidant (AOX) molecule capable of absorbing the intermediate free radicals, or free-radical scavengers, interrupts this chain reaction.