Oxidation of lipids and membranes I: in vitro formation of peroxidative lipid polymers.

Fluorescent polymers were obtained by oxidizing partly emulsified linolenic acid with different oxidants. The speed of formation of polymers differed for the various oxidants, and the difference was not a simple function of the oxidation potential. The speed of polymerization also depended on the nature of the emulsion. The presence of egg albumen in the emulsion enhanced polymer formation with all oxidants. When the oxidants used are arranged in the order of decreasing speed of polymer formation, the order is different in the presence of albumen from what it is in the absence of albumen. With different oxidation catalysts most antioxidants and amino acids tested enhanced polymerization. In oxidation with ferric ions, with K-dichromate, and without added oxidants the only antioxidants which delayed polymerization were "inhibitors." "Retarders" enhanced polymerization. With KMnO4 slight delay was caused by some retarders. The findings indicate that not only oxidation catalysts, but also proteins, amino acids, and antioxidants enhance polymerization. The possibility is suggested that in animal cells lipid pigment formation might represent a mechanism for neutralizing free radicals.