4-hydroxy Nonenal (4-HNE) is a major aldehyde produced during the lipid peroxidation of ω-6 polyunsaturated fatty acids, such as arachidonic acid and linoleic acid. It is considered a potential causal agent in numerous diseases, including chronic inflammation, neurodegenerative diseases, atherosclerosis, diabetes, and cancer, in part because it covalently modifies DNA and proteins resulting in genetic mutations and altered cell signaling, respectively. 4-HNE Alkyne is a form of 4-HNE with a terminal alkyne. Such terminal alkyne groups can be used in linking reactions, known as click chemistry, characterized by high dependability and specificity of azide-alkyne bioconjugation reactions. Click chemistry has only recently been applied to the study of oxidized lipids.
Peroxidation of common ω-6 polyunsaturated fatty acids (PUFAs) such as linoleic acid, DGLA, and arachidonic acid can give rise to 4-HNE. 4-HNE is cleared rapidly from the plasma and undergoes enterohepatic circulation as a glutathione conjugate in the rat. About two thirds of an administered dose of 4-HNE is excreted within 48 hours in the urine, primarily in the form of mercapturic acid conjugates. The C-1 aldehyde of 4-HNE is reduced to an alcohol in about half of these metabolites. The remainder are C-1 aldehydes or have been oxidized to C-1 carboxylic acids. These aldehydes and carboxylic acids can also form γ-lactols and γ-lactones, respectively, producing at least 4 or 5 end urinary metabolites of 4-HNE in vivo.