AbstractThe formation and properties of the fluorescent compounds originated in the browning reactions of phospholipids have been investigated. The compounds exhibited fluorescence with excitation maximum 345–350 nm and emission maximum at 420–430 nm, which were similar to those of lipofuscin and fluorescent substances derived from the reaction of oxidized fatty acids with glutathione. The fluorescence of the compound was affected neither with the pH 2–11 nor by treatment with sodium borohydride. The fluorescent compounds formed in the browning reaction of peroxidized phosphatidylethanolamine are produced, mainly, by interaction of the amine group of phosphatidylethanolamine and saturated aldehydes produced through the decomposition of fatty acid hydroperoxides of phosphatidylethanolamine. Phospholipids do not interact per se with bovine serum albumin, and their interaction is similar to that of polyunsaturated fatty acid hydroperoxides: the phospholipids give secondary products (aldehydes) that subsequently react with protein.