Determination of lipid conjugated dienes with tetracyano-ethylene-14C: Significance for study of the pathology of lipid peroxidation

A method for quantitative analysis of conjugated diene unsaturation has been developed utilizing tetracyanoethylene-¹⁴C (TCNE-¹⁴C) in a Diels-Alder condensation. The amount of C¹⁴ found in the Diels-Alder adduct has been shown to be a measure of conjugated diene content. The method has proven successful in analysis of a variety of triglycerides, phospholipids, and peroxidized tissue lipids. In the course of this work, a method for removing the fatty acid substituents from phospholipids using lithium aluminum hydride was developed. TCNE-¹⁴C analysis for conjugated dienes in rat liver microsomal lipids after dosing with CCl₄ or BrCCl₃ has provided conclusive evidence that the increase in ultraviolet absorption at 233 nm of these lipids is due to conjugated dienes.