Phosphatidylethanolamine (PE) has an antioxidant effect by itself or in the presence of tocopherol. Due to this antioxidant action, it plays a role as an intracellular storage of docosahexaenoic acid （DHA） which is preferentially taken up by PE. Plasmalogen-type PE（P-PE）present in the brain protects from DHA radical damage more strongly by the vinyl ether bond in its structure. Brain PE produces N-acyl ethanolamine from N-acyl PE by phospholipase D. It acts as a ligand for various receptors represented by anandamide (a blissful substance) and exerts various physiological functions. Decreased DHA-binding P-PE (DHA-P-PE) in the brain and lipoproteins loaded from the liver with DHA-P-PE were associated with the pathology of dementia, 7 years before mild onset. DHA-P-PE found in the skin is recognized by a specific phospholipase A2G2F as a substrate and metabolized to lyso-DHA-P-PE, which is a psoriasis responsible metabolite. Lyso-DHA-P-PE was recognized as a novel lipid mediator that regulates skin homeostasis and diseases. PE affects the utilization of PE methyl transferase-mediated phosphatidylcholine production in the placenta and fetus in the choline metabolism pathway during pregnancy. PE unevenly distributed in the inner leaflet of the cell membrane has its unsaturated fatty acid and is protected from radical damage from the outside. Furthermore, PE interacts with tocopherols present in the membrane, and protects fatty acids with ethanolamine and vinyl ether bond.

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