Development of stable isotope dilution analyses for components of the vitamin B6 group in foods

全世界的社会都认为B6维生素供应不足。由于食物中天然存在的八种B6维生素的生物利用度差异很大，有关食物中维生素分布的知识对于验证摄取数据和准确的饮食建议至关重要。这对糖基化维生素尤其重要，它在植物性食品中含量很高，生物利用度特别低。根据目前的技术水平，只有通过LC-MS才能准确分析所有维生素。在这方面，一个瓶颈是缺乏吡哆醇葡萄糖苷形式的参考化合物。此外，LC-MS定量通常会受到基质干扰的阻碍。因此，本项目旨在合成4-和5-O-(β-D-葡萄糖基)-吡哆醇，并对食品中所有准确的B6维生素进行分析。为了定量八种B6维生素，将合成各自的稳定同位素制剂，并将其用作稳定同位素稀释分析的内标。经过充分的验证，该方法的应用将在小规模的市场调查中得到验证。该方法将在后续研究中作为测定血浆中B6的基础，以便准确地评估吡哆醇糖苷的生物利用度，这里将首次明确描述这些糖苷的特征。

An insufficient supply with vitamins of the B6 group is assumed in all society over the world. As the eight B6 vitamers naturally occurring in foods reveal strongly varying bioavailability, knowledge on vitamer distribution in foods is essential for validated uptake data and accurate dietary recommendations. This is in particular crucial for glucosylated vitamers, which are highly abundant in foods of plant origin and show particularly low bioavailabilities. According to the current state of the art an accurate analysis of all vitamers is only possible by LC-MS. In this regard a bottleneck is the lacking availability of reference compounds for the glucysidic forms of pyridoxine. Besides this, a quantitation by LC-MS generally is hindered by matrix interferences. Therefore, the project presented here aims at chemical syntheses of 4- and 5-O-(beta-D-glucopyranosyl)-pyridoxine and analysis of all accurring B6 vitamers in foods. For quantitation of eight B6 vitamers the respective stable isotopologues will be synthesized and applied as internal standards in stable isotope dilution assays. Following a thorough validation, application of the method will be proved in a small-scale market survey. The method will serve in follow-up studies as the basis for a determination of B6 in blood plasma in order to assess accurately the bioavailability of the pyridoxine glucosides that will be characterized unambiguously here for the first time.