A relay model of lipid peroxidation in biological membranes

Abstract

It is believed that in lipid peroxidation in membranes an important role is played by unoxygenated hydrocarbon radicals whose movement within the hydrocarbon moiety of the membrane is through intra- and intermolecular relay rearrangements (H-shift). In membranes containing a high concentration of polyunsaturated lipids, the radical mobility may be higher than the laterial diffusion of the lipids allowed by the microviscosity of the membrane. The action mechanism of antioxidants having a side hydrocarbon tail (e.g., tocopherols) rests upon the relay radical reaction, as a multistep process. The initial step is the relay transfer of unoxygenated free radical to the side hydrocarbon chain of antioxidant. In subsequent steps the aroxyl radical is formed by the intramolecular rearrangement of radical in an antioxidant molecule. Hence, the inhibitor interrupts the propagation chain in the membrane by the scavenge of unoxygenated hydrocarbon radical.