The Formation of Fluorescent Substances by Lipidperoxides.

Abstract

Fluorescent substances were formed by the reaction of various amino compounds and malondialdehyde (MDA), the end product of lipid peroxidation. Reduction of these fluorescent substances with sodium borohydride resulted in disappearance of the fluorescence. Fluorescent substances were also obtained from the reaction of UV-irradiated phosphatidylethanolamine or methyl linolenate with 1-aminopentane, and the increase in fluorescent substances was accompanied by a decrease of thiobarbituric acid (TBA) reactants during the reaction. The resulting flnorescent substances were soluble in chloroform-methanol (2 : 1), and were not affected by treatment with sodium borohydride. On the other hand, fluorescent substances were not formed from conjugated diene compound, which is one of the primary compounds of lipid peroxidation. Lipofuscin-like fluorescent substances isolated from rat liver microsomes showed a similar characteristic to those derived from lipid peroxide and 1-aminopentane in vitro. These results suggested that lipofuscin-like fluorescent substances were not formed from MDA and amino compounds, but from TBA reactants, which were formed during the decomposition of conjugated diene compound to MDA in lipid peroxidation, by reaction with amino compounds.