2,2'-AZOBIS (4-METHOXY-2,4-DIMETHYLVALERONITRILE), A NEW LIPID-SOLUBLE AZO INITIATOR - APPLICATION TO OXIDATIONS OF LIPIDS AND LOW-DENSITY-LIPOPROTEIN IN SOLUTION AND IN AQUEOUS DISPERSIONS

Both hydrophilic and hydrophobic azo radical initiators are useful for in vitro studies on lipid peroxidation and its inhibition by antioxid ants. In the present study, a new lipophilic azo compound, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (MeO-AMVN), was introduced and i ts action as an initiator of lipid peroxidation was examined. MeO-AMVN decomposed about 15 times as fast as 2,2'-azobis(2,4-dimethylvaleroni trile) (AMVN), a widely used lipophilic azo initiator, and MeO-AMVN-in itiated free radical-mediated peroxidations of lipids in organic solut ion and in micelles, membranes, and low-density lipoprotein in aqueous dispersions with much smaller concentration than AMVN. The rate of ch ain initiation by MeO-AMVN varied significantly with the medium and de creased with increasing viscosity of the medium. The advantage and cau tions for using MeO-AMVN as a lipophilic radical source have been disc ussed and it has been concluded that MeO-AMVN, when properly used, is a useful radical initiator of lipid peroxidations especially in micell es, membranes, and lipoproteins. (C) 1998 Elsevier Science Inc.