Separation of α-tocotrienol oxidation products and eight tocochromanols by HPLC with DAD and fluorescence detection and identification of unknown peaks by DAD, PBI-EIMS, FTIR, and NMR

Abstract

Tocotrienols, like tocopherols, are members of the vitamin E family. While tocopherols (T) have been studied intensively, only recently have tocotrienols (T3) received increased attention due to their special health benefits. However, these positive attributes of T3 are probably lost as a result of degradation during food storage and processing, and there is little information about their oxidation products. Of particular interest are the oxidation products of α-tocotrienol (α-T3) as this is the least thermostable T3 isomer with the highest rate of degradation. The objective of this study was therefore to develop a reliable method for the determination of the most important oxidation products of α-T3 along with other tocochromanol isomers. We developed a high-performance liquid chromatography method with diode array detection, fluorescence detection, and a particle beam interface electron impact mass spectroscopy in order to separate the most important oxidation products of α-T3 (α-T3 spirodimers/spirotrimers, α-tocotrienoldihydroxy dimer, 7-formyl-β-tocotrienol (7-FβT3), 5-formyl-γ-tocotrienol (5-FγT3), α-tocotrienolquinone (α-T3Q), and α-T3Q dimers and α-tocotrienolquinone epoxides (α-T3QE)) from eight tocochromanol isomers. Furthermore, we sought to identify the as yet unknown oxidation products 5-FγT3, 7-FβT3, α-T3Q-dimer, and α-T3QE. Of these, 5-FγT3 was fully characterized by Fourier transform infrared spectroscopy and (1)H and (13)C nuclear magnetic resonance spectroscopy.

Comparison of dietary tocotrienols from barley and palm oils in hen's egg yolk: transfer efficiency, influence of emulsification, and effect on egg cholesterol

“…After thorough mixing and centrifugation at 3000 × g for 10 min, the supernatant was collected. T3 and T were determined using the normal phase HPLC method of Büsing and Ternes …”

“…T3 and T were determined using the normal phase HPLC method of Büsing and Ternes. 19 For determination of T and T3 vitamers in the lyophilized egg yolk, the HPLC method of Sookwong et al 20…”

A review of characterization of tocotrienols from plant oils and foods

“…However, in fats and oils, α-T3 shows the fastest degradation and the lowest relative antioxidant activity to protect against lipid peroxidation in relation to the other T3 isomers. This phenomenon may be due to the fact that at high temperature, high concentration and in the presence of oxygen, α-tocochromanols can easily act as a prooxidant by undergoing side reactions, leading to the loss of antioxidant efficiency [16].…”

“…Unlike T, T3 are reported to inhibit cholesterol biosynthesis and to have neuroprotective properties [22,23]. Moreover, α-T3 has outstanding antioxidant activity in liver microsomes, 40-60 times greater than that of α-tocopherol (α-T) [24], and shows special anti-carcinogenic properties [16].…”

Separation and determination of estrogen in the water environment by high performance liquid chromatography-fourier transform infrared spectroscopy

“…High performance liquid chromatography (HPLC) is an important way to analyze organic compounds with high boiling point and high molecular weight12, but it cannot determine quantitatively the unknown component or structure3. Fourier transform infrared spectrometry (FTIR) has been considered a fingerprint identification technology since the birth of FTIR.…”