α-Tocopheryl phosphate:: A novel, natural form of vitamin E

We have detected a-tocopheryl phosphate in biological tissues including liver and adipose tissue, as well as in a variety of foods, suggesting a ubiquitous presence in animal and plant tissue. a.-Tocopheryl phosphate is a water-soluble molecule that is resistant to both acid and alkaline hydrolysis, making it undetectable using standard assays for vitamin E. A new method was therefore developed to allow the extraction of both alpha-tocopheryl phosphate and alpha-tocopherol from a single specimen. We used ESMS to detect endogenous alpha-tocopheryl phosphate in biological samples that also contained alpha-tocopherol. Due to the significance of these findings, further proof was required to unequivocally demonstrate the presence of endogenous a-tocopheryl phosphate in biological samples. Four independent methods of analysis were examined: HPLC, LCMS, LCMS/MS, and GCMS. alpha-Tocopherol phosphate was identified in all instances by comparison between standard a-tocopheryl phosphate and extracts of biological tissues. The results show that alpha-tocopheryl phosphate is a natural form of vitamin E. The discovery of endogenous a-tocopheryl phosphate has implications for the expanding knowledge of the roles of a-tocopherol in biological systems. (c) 2005 Elsevier Inc. All rights reserved.