Studies on Peroxidized Lipids. III.1) Fluorescent Pigments derived from the Reaction of Malonaldehyde and Amino Acids

Abstract

Reactions of malonaldehyde (MA), a secondary product of lipid peroxidation, with amino acids and related compounds were performed under mild conditions. Thus, mixtures of 200 mM MA-50 mM amino acid (or related compound) were treated at around pH 7 at 37°C. The major fluorescent products Ig, Ige and Ih were isolated as crystals from the reaction mixtures of glycine, its ethyl ester and n-hexylamine, respectively, and their structures were established to be 1-substituted 4-methyl-l,4-dihydropyridine-3,5-dicarbaldehyde (I). The compounds showed fluorescence with [formula omitted] 365, 403 nm and [formula omitted] 440–460 nm. The reaction mixtures of MA and amino acids except for l-tryptophan, crysteamine and l-cysteine exhibited the same fluorescence spectra. The reactions of MA with cysteamine and l-cysteine produced a different type of fluorescent products. Under the reaction conditions employed here, formation of conjugated Schiff bases (III) as described by Chio and Tappel (Biochemistry, 8, 2821 (1969)) could not be detected. The fluorescence spectrum of I resembled those of lipofuscin pigments extracted from the tissue homogenates. © 1981, The Pharmaceutical Society of Japan. All rights reserved.