Analysis of minor vitamin E homologues in natural products

Abstract

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.

Free and Esterified Tocopherols, Tocotrienols and Other Extractable and Non-Extractable Tocochromanol-Related Molecules: Compendium of Knowledge, Future Perspectives and Recommendations for Chromatographic Techniques, Tools, and Approaches Used for Tocochromanol Determination

“…T1s and T2s are less common in nature and can be found in lower concentration than Ts and T3s [ 14 , 16 ]. 11′-α-T1 was first isolated and purified from palm and rice bran oils in 1995 [ 69 ].…”

“…The challenge with the determination of esterified tocochromanols is not only associated with the procedure of tocol determination but also with lack of standards. Similarly, commercial standards for some other tocochromanols are not available, e.g., the well-known plastochromanol-8 (PC-8) [ 12 , 13 ], tocodienols (T2s) and tocomonoenols (T1s) [ 14 , 15 , 16 , 17 ]. Research on the latter two has been gaining momentum in the past decade, and new commercial standards of tocochromanols or their metabolites are released to the market every year.…”