Analysis of minor vitamin E homologues in natural products

Fruits and seeds are naturally rich in antioxidants, which provide protection against UV light and oxygen. Vitamin E is a typical antioxidant, and offers radical scavenging activity to prevent the oxidation of the polyunsaturated fatty acids in cell membranes, contribute to homeostasis, and support the biological functions of animals and plants. Tocopherol and tocotrienol are forms of vitamin E widely found in natural products. In addition, recent studies have demonstrated the existence of minor homologues, namely tocomonoenol and tocodienol. The characteristic physiological functions of vitamin E homologues are dependent on their structure. Consequently, the nutritional functionality of the minor homologues has attracted much research interest, which relies on highly accurate analytical methods. This review aimed to summarize the literature concerning the diversity of tocomonoenol and tocodienol, as well as reports on the various methods for their analysis and detection in different sample matrices. This paper is expected to contribute to future exploratory research and the functional evaluation of minor homologues.