α-Tocopherol is the most biologically active form of vitamin E, a fat-soluble antioxidant that protects cell membranes from oxidative damage by scavenging free radicals. It consists of a chromanol ring with a phytyl side chain and is naturally found in vegetable oils, nuts, and green leafy vegetables. Used as a dietary supplement and food preservative (E307), it prevents lipid peroxidation in fats and oils. The compound exhibits stereoisomerism with the RRR configuration being the natural form predominant in plants. It plays roles in immune function, gene expression, and neurological health. Chemically stable under normal conditions but sensitive to oxidation when exposed to air, light, or heat in the presence of metals.