Identification of α-Tocotrienolquinone Epoxides and Development of an Efficient Molecular Distillation Procedure for Quantitation of α-Tocotrienol Oxidation Products in Food Matrices by High-Performance Liquid Chromatography with Diode Array and Fluorescence Detection

Abstract

The aim of this study was to investigate the most important oxidation products of α-tocotrienol (α-T3) along with other tocochromanols in lipid matrices and tocotrienol-rich foods. For this purpose, an efficient molecular distillation procedure was developed for the extraction of analytes, and α-T3-spiked and thermally oxidized natural lipids (lard and wheat germ oil) and α-T3-rich foods (wholemeal rye bread and oil from dried brewer's spent grain) were investigated through HPLC-DAD-F. The following α-T3 oxidation products were extractable from lipid matrices along with tocochromanols: α-tocotrienolquinone (α-T3Q), α-tocotrienolquinone-4a,5-epoxide (α-T3Q-4a,5-E), α-tocotrienolquinone-7,8-epoxide (α-T3Q-7,8-E), 7-formyl-β-tocotrienol (7-FβT3), and 5-formyl-γ-tocotrienol (5-FγT3). Recovery rates were as high as 88% and enrichment factors up to 124. The proposed method allows the investigation of α-T3Q, α-T3Q-4a,5-E, α-T3Q-7,8-E, 7-FβT3, and 5-FγT3 in small quantities (<0.78 μg/g) in lipid matrices, which is necessary for the investigation and analysis of the formation kinetics of these oxidation products in fat, oils, and tocotrienol-rich foods.

Identification of α-Tocopherol and Its Oxidation Products by Ultra-Performance Liquid Chromatography Coupled with Quadrupole Time-of-Flight Mass Spectrometry

“…The same result was found in α-tocotrienol: researchers found homologous aldehydic oxidation products of α-tocotrienol after thermal oxidation, such as 5-formyl-γ-tocotrienol (5-F-γ-T3) and 7-formyl-β-tocotrienol (7-F-β-T3). 22,32 The carbonyl groups on the benzene ring of these compounds could easily combine with the hydroxyl groups in the ortho position, thus forming intramolecular hydrogen bonds, further leading to relatively insignificant antioxidant properties compared to αtocotrienol. What is interesting is that, in different matrices, compared with 5-formyl-γ-tocochromanols, 7-formyl-β-tocochromanols were always less likely to form.…”

Chemical Composition, Antimicrobial, Antioxidant, and Antiproliferative Properties of Grapefruit Essential Oil Prepared by Molecular Distillation

“…Molecular distillation is a special liquid-liquid separation technology under high vacuum, which is employed as a separation process in the food industry [32,33]. Molecular distillation can divide the EO mixture into two different phases according to the free path of different molecules at low temperature.…”

Antioxidant and Anticancer Activities of Essential Oil from Gannan Navel Orange Peel

“…To avoid this problem, we used a molecular distillation method to remove them. The separation principle of molecular distillation is based on the difference of molecular mean free path [ 16 ]. It is very suitable for heat sensitive compounds and characterized by very high vacuum so that the product can be obtained at low temperature [ 17 , 18 ].…”