The Behaviour of Vitamin E in Membranes
The neutral lipids of the vitamin E family (tocopherols and tocotrienols) are well known antioxidants with α-tocopherol (α-Toc) being the sole tocopherol retained in mammalian tissues after absorption from the diet. Because of their high hydrophobicity, tocopherols partition easily into biological membranes. The location and dynamic behavior of tocopherols and tocotrienols in phospholipid membranes is essential information for describing the mechanism(s) of action of these molecules. The bilayer orientation and dynamics are central to our comprehension of their action as antioxidants, protecting free radical-induced peroxidation of polyunsaturated phospholipids. Tocopherols and tocotrienols may also affect sub-membrane domains such as lipid rafts, and the unusual biological activities for non-α-tocopherols is potentially explainable by their oxidative conversion to arylating quinones. In this review we describe recent work on the location and behavior of mainly α-Toc in model bilayers.