Gamma tocopherol, its dimmers, and quinones: Past and future trends

Gamma-tocopherol (γ-T), the major form of vitamin E in many plant seeds and products derived from them, has been attracting increasing attention because of its health-promoting roles. However, the underlying molecular mechanisms are still unclear, to some degree. Furthermore, its dimmers and quinones are expected to be potential nutritious and pharmaceutical agents, however, the knowledge about these dimmers (γ-TBD and γ-TED) and quinones (para- and ortho-quinones) is relatively limited. Thus, a comprehensive summary of the history, chemical structure, source, determination, absorption, transport, and metabolism of its dimmers and quinones compared to γ-T has been reviewed. In addition, the antioxidant activity (AOA) and non-AOA activity of these substances are highlighted. It is suggested that more special attention be paid to the dimmers and quinones for better understanding and further applications.