This work represents the first systematic speciation study of selenium (Se) in plasma from subjects participating in a pilot study for a cancer prevention trial (PRECISE). This involved supplementation of elderly British and Danish individuals with selenised yeast for 6 months and 5 years, respectively, at 100, 200, and 300 μg Se/day or placebo. Speciation data was obtained for male plasma using HPLC-ICP-MS and HPLC-ESI-MS/MS. With the proposed strategy, approximately 1.5 mL of plasma was needed to determine total Se concentration and the fractionation of Se in high molecular weight (HMW) and low molecular weight (LMW) pools, and for quantification and identification of small Se species. For the first time, Se-methyl-selenocysteine (MSC) and methyl-2-acetamido-2deoxy1-seleno-β-d-galactopyranoside (Selenosugar-1) were structurally confirmed in plasma after supplementation with selenised yeast within the studied range. Determination of selenomethionine (SeMet) incorporated non-specifically into albumin (SeALB) was achieved by HPLC-ICP-MS after hydrolysis. By subtracting this SeMet concentration from the total Se in the HMW pool, the concentration of Se incorporated into selenoproteins was calculated. Results from the speciation analysis of the free Se metabolite fraction (5% of total plasma Se) suggest a significant increase in the percentage of Se (as SeMet plus Selenosugar-1) of up to 80% of the total Se in the LMW fraction after 6 months of supplementation. The Se distribution in the HMW fraction reflects a significant increase in SeALB with Se depletion from selenoproteins, which occurs most significantly at doses of over 100 μg Se/day after 5 years. The results of this work will inform future trial design.

这项工作代表了参与癌症预防试验 (PRECISE) 试点研究的受试者血浆中硒 (Se) 的首次系统形态研究。这涉及分别以 100、200 和 300 μg Se/天或安慰剂向英国和丹麦老年人补充硒化酵母 6 个月和 5 年。使用 HPLC-ICP-MS 和 HPLC-ESI-MS/MS 获得男性血浆的形态数据。使用所提出的策略，需要大约 1.5 mL 的血浆来确定总 Se 浓度和高分子量 (HMW) 和低分子量 (LMW) 池中的 Se 分馏，以及定量和鉴定小 Se 物种。首次，Se-甲基-硒代半胱氨酸（MSC）和甲基-2-乙酰氨基-2deoxy1-seleno-β- d在研究范围内补充硒化酵母后，-吡喃半乳糖苷 (Selenosugar-1) 在血浆中得到结构证实。水解后通过 HPLC-ICP-MS 测定非特异性掺入白蛋白 (SeALB) 的硒代甲硫氨酸 (SeMet)。通过从 HMW 池中的总 Se 中减去该 SeMet 浓度，计算出掺入硒蛋白中的 Se 浓度。游离硒代谢物部分（总血浆硒的 5%）的形态分析结果表明，在 LMW 部分后，硒（作为 SeMet 加 Selenosugar-1）的百分比显着增加，最高可达总硒的 80%。 6个月的补充。HMW 部分中的 Se 分布反映了 SeALB 的显着增加，硒蛋白中的 Se 耗竭，这在 5 年后每天超过 100 μg Se/天的剂量下最显着。这项工作的结果将为未来的试验设计提供信息。