6533b82cfe1ef96bd128e9c6

RESEARCH PRODUCT

[39] Lipoperoxyl radical-scavenging activity of vitamin A and analogs in homogeneous solution

subject

description

Publisher Summary This chapter describes the assay method for determining the reactivity of all- trans -retinol and other natural and synthetic retinoids, with radicals generated by reaction of the lipid-soluble azo initiator 2,2 ' -azobis(2,4-dimethylvaleronitrile) (AMVN) with methyl linoleate. The chapter discusses the general principles for measuring antioxidant activity. The oxidation of linoleic acid methyl ester (LAME) is the simplest model for studying the oxidation of polyunsaturated lipids and has been widely adopted to evaluate antioxidant activity. Because linoleic acid has two double bonds, peroxidation occurs at the bisallylic hydrogens and generates conjugated diene hydroperoxides quantitatively. Therefore, lipid oxidation can be followed quantitatively by ultraviolet (UV) measurements of the conjugated dienes formed. To obtain a constant rate of chain initiation, which is essential to kinetic studies, azo initiators are commonly used. Antioxidant parameters can be quantitatively obtained from the lipid model system if substrate and reaction conditions are carefully controlled.