Antioxidant activity of aminoethylcysteine ketimine decarboxylated dimer on copper-induced LDL oxidation.

Aminoethylcysteine ketimine decarboxylated dimer (AECK-DD), a member of a family of natural cyclic sulfur-containing aminoacids, recently detected in biological samples, protects low density lipoprotein (LDL) against copper-mediated oxidation, as assessed by monitoring the kinetics of conjugated diene formation, thiobarbituric acid-reactive substances production and LDL-tryptophan fluorescence quenching. Moreover, AECK-DD exerts a protective effect also against metal-independent, peroxyl radical-induced lipoprotein oxidation. It is of note that the concentrations exerting a protective effect against LDL oxidation are similar to those found in biological samples.