4-Hydroxynonenal

4-Hydroxynonenal (4-HNE) is a highly reactive α,β-unsaturated hydroxyalkenal and one of the most significant and extensively studied end-products of lipid peroxidation (LPO). It is formed during oxidative stress when reactive oxygen species (ROS) attack polyunsaturated fatty acids, particularly omega-6 fatty acids like arachidonic and linoleic acids, in biological membranes. 4-HNE acts as a "second messenger" of oxidative stress, propagating and extending the damaging effects of free radicals throughout the cell and even to distant sites.

4-Hydroxynonenal, or 4-hydroxy-2-nonenal or 4-HNE or HNE, (C9H16O2), is an α,β-unsaturated hydroxyalkenal that is produced by lipid peroxidation in cells. 4-HNE is the primary alpha,beta-unsaturated hydroxyalkenal formed in this process.