Simultaneous determination of RRR- and SRR-alpha-tocopherols and their quinones in rat plasma and tissues by using chiral high-performance liquid chromatography.

Abstract

We established a method to simultaneously determine RRR- and SRR-alpha-tocopherol (alpha-Toc) and their quinones in biological samples by chiral-phase high-performance liquid chromatography (HPLC). Alpha-Toc had a shorter retention time than alpha-tocopherylquinones (alpha-TQ), and 2-ambo-alpha-Toc was completely separated into two peaks; the first peak was RRR-alpha-Toc and the second SRR-isomer by chiral HPLC connected Chiralcel OD-H column and Sumichiral OA4100 column. In contrast, of the two peaks of alpha-TQ, the first was the SRR-isomer. We also investigated differences in the distribution of RRR- and SRR-alpha-TQ in rat tissues after oral administration of 2-ambo-alpha-Toc by the above HPLC method. Rats deficient in vitamin E were divided into two groups, control and experimental, and tissues were collected at 3, 6, and 24 h after oral 2-ambo-alpha-Toc administration. The concentrations of RRR- and SRR-alpha-Toc and their quinones in plasma and each tissue were determined. The concentration of SRR-alpha-TQ in plasma and adrenal glands was not significantly different from RRR-alpha-TQ. However, the concentration of SRR-alpha-TQ in liver up to 6 h after oral administration was higher than that of RRR-alpha-TQ, and SRR- and RRR-alpha-TQ levels were similar at 24 h after oral administration. Therefore, we may assume that the formation of alpha-TQ in vivo was not different between RRR- and SRR-isomer and that it was not affected by the presence of alpha-Toc stereoisomers.