STRUCTURAL FEATURES AND PHARMACOLOGICAL IMPORTANCE OF VITAMIN E AS AN ANTIOXIDANT IN HUMANS

Abstract

Oxidative stress, resulting from an imbalance between reactive oxygen species production and antioxidant defense mechanisms, plays a central role in the pathogenesis of numerous chronic and degenerative diseases. Vitamin E represents a major group of lipid-soluble antioxidants that protect cellular membranes and lipoproteins from oxidative damage. This review comprehensively summarizes the chemistry, structural classification, transport mechanisms, and pharmacological roles of vitamin E, with particular emphasis on its antioxidant function in human health. Vitamin E encompasses eight naturally occurring tocochromanols, including four tocopherols and four tocotrienols, each exhibiting distinct biological activities influenced by their chemical structure, stereochemistry, and metabolism. The review highlights dietary sources, physicochemical characteristics, and the preferential biological activity of α-tocopherol mediated through the α-tocopherol transfer protein. Furthermore, the mechanistic role of vitamin E as a chain-breaking antioxidant in preventing lipid peroxidation is discussed, along with its synergistic interaction with other antioxidants such as vitamin C. The pharmacological significance of vitamin E in the prevention and modulation of cardiovascular diseases, cancer, cataracts, neurodegenerative disorders such as Alzheimer’s disease, immune dysfunction, and infectious diseases is critically evaluated. Despite promising mechanistic and observational evidence, clinical outcomes of vitamin E supplementation remain inconsistent, emphasizing the importance of isoform specificity, dosage, and population characteristics. Overall, this review underscores the multifaceted biological roles of vitamin E and highlights future research directions necessary to optimize its therapeutic and preventive applications.