Lipid peroxidation

Lipid peroxidation is an autocatalytic, radical-mediated oxidative degradation of polyunsaturated fatty acids (PUFAs) in cell membranes, lipoproteins, and lipid droplets, initiated when reactive oxygen species (ROS) or other radicals abstract a bis-allylic hydrogen atom from a PUFA chain. The resulting lipid radical reacts with molecular oxygen to form a lipid peroxyl radical, which propagates the chain reaction and yields end-products including malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) — reactive aldehydes that form adducts with proteins and DNA. Elevated lipid peroxidation is implicated in membrane dysfunction, mitochondrial damage, and ferroptosis, a form of regulated cell death driven by uncontrolled phospholipid peroxidation that is increasingly linked to neurodegenerative and cardiovascular ageing pathology.