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

全世界所有社会都认为B6族维生素供应不足。由于食物中天然存在的八种B6维生素显示出强烈的生物利用度差异，因此了解维生素在食物中的分布对于验证摄取数据和准确的饮食建议至关重要。这对于葡萄糖基化维生素尤其重要，葡萄糖基化维生素在植物来源的食物中含量非常丰富，并且显示出特别低的生物利用度。根据现有技术，所有维生素的准确分析仅可能通过LC-MS进行。在这方面，瓶颈是缺乏用于吡哆醇的糖苷形式的参考化合物的可用性。除此之外，LC-MS定量通常会受到基质干扰的阻碍。因此，本课题的研究目标是4-和5-O-（β-D-吡喃葡萄糖基）-吡哆醇的化学合成及食品中所有维生素B6的分析。为了定量八种B6维生素，将合成相应的稳定同位素体，并将其用作稳定同位素稀释测定中的内标。经过全面验证后，将在小规模市场调查中证明该方法的应用。该方法将在后续研究中作为血浆中B6测定的基础，以准确评估吡哆醇葡萄糖苷的生物利用度，这将是首次明确描述。

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.