Unveiling the antioxidant superiority of α-tocopherol: Implications for vitamin E nomenclature and classification

Since the discovery of tocopherols a century ago, α-tocopherol has been distinguished for its unique biological functions. In this study, we aim to elucidate the unique characteristics of α-tocopherol from a chemical perspective. Utilizing density functional theory (DFT) calculations, we evaluated the thermodynamic and kinetic properties of tocopherols, tocotrienols and their oxidation products. Our findings highlight the superior thermodynamic and kinetic properties of α-tocopherol. Although tocopherol substrates generally exhibit similar reactivities, α-tocopherol is distinguished by a larger gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in intermediates, indicating a potential for greater energy release and favoring reaction progression. Moreover, α-tocopherol shows enhanced efficiency in quenching radical intermediates, especially when combined with vitamin C. All these dates provide valuable support for the naming of vitamin E.