No abstract

The dynamics of the chain initiation of the oxidations of lipids by hyponitrites were studied in organic homogeneous solution and in aqueous dispersions of micelles and liposomal membranes. Di-t-butyl and distearyl hyponitrites were used in order to examine the effect of bulkiness of the alkoxyl radicals in different reaction media. Both hyponitrites induced the free radical-mediated chain oxidations of methyl linoleate in homogeneous solution and in aqueous emulsions and also of soybean phosphatidylcholine liposomal membranes. In aqueous dispersions, these lipophilic hyponitrites generated free radicals in the lipid compartment and aqueous radical-scavenging antioxidants could not suppress the oxidations induced by these hyponitrites. The efficiency of chain initiation decreased in the order of homogeneous solution > micelles > liposomal membranes in accordance with increasing viscosity of the medium. It was also dependent on the size of alkoxyl radical and distearyl hyponitrites was less efficient than di-t-butyl hyponitrite in initiating the chain oxidation in all of the above reaction media.