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