Metabolism of Gamma-tocopherol in the Liver of Male Sprague-Dawley Rat

Vitamin E (VE) plays important roles in the physiological and biochemical processes of animals and humans. However, VE is an unique vitamin that has not been understood thoroughly because the metabolites of VE are very complicated and hard to be analysed. This experiment was conducted to study the metabolism of γ-tocopherol, one of 8 VE isomers, in the liver post-mitochondrial supernatant (S9) of male Sprague-dawley rat (Rattus norvegiens, SD-rat) using a novel approach. The results showed that an optimal reactive system of γ-tocopherol metabolism in vitro was composed of 5 mg/ml of S9, 8 μg/ml of γ-tocopherol, 1 mmol/ml of nicotine amide adenine dinucleotide phosphate (NADPH) and 45 min of reactive time at 35°C. The metabolites of γ-tocopherol could be successfully analyzed using gradient elution and reverse-phase high-performance liquid chromatography (RP-HPLC). A main metabolite was identified as ω-hydroxylate, a side chain of γ-tocopherol, when the structure of γ-tocopherol metabolites was determined using gas chromatography-mass spectrometry (GC-MS). A conclusion was drawn that ω-hydroxylate, a main metabolite of γ-tocopherol, could be most utilized by SD-rat and other mammals.