Vonderheide Anne P, Wrobel Kazimierz, Kannamkumarath Sasi S, B'Hymer Clayton, Montes-Bayón Maria, Ponce De León Claudia, Caruso Joseph A
Department of Chemistry, University of Cincinnati, Ohio 45221-0172, USA.
J Agric Food Chem. 2002 Sep 25;50(20):5722-8. doi: 10.1021/jf0256541.
Brazil nuts have been classified as the foodstuffs that contain the highest level of unadulterated selenium, an essential trace element that appears to prevent cancer. To date, characterization of the selenium species in brazil nuts has not yet been investigated. In this work, various sample preparation approaches, including microwave extractions and enzymatic treatments, are examined with the goal of species preservation and subsequent selenium speciation; of these approaches, an enzymatic treatment with Proteinase K proved most effective. High-performance liquid chromatography (HPLC) separation strategies and inductively coupled plasma mass spectrometry (ICP-MS) detection schemes will also be presented. Extracts are evaluated against available standards for the commercially obtainable seleno-amino acids, selenomethionine (SeMet), selenoethionine (SeEt), and selenocystine (SeCys); selenomethionine was demonstrated to be the most abundant of these seleno-amino acids. Further characterization of unidentified selenium-containing peaks is attempted by the employment of several procedures, including electrospray-mass spectrometry (ES-MS). A peptide structure was identified; however, this was considered a tentative proposal due to the large background produced by the extremely complicated brazil nut matrix.
巴西坚果被归类为含未掺杂硒水平最高的食品，硒是一种似乎能预防癌症的必需微量元素。迄今为止，尚未对巴西坚果中的硒形态进行表征研究。在这项工作中，研究了各种样品制备方法，包括微波萃取和酶处理，目的是保存形态并随后进行硒形态分析；在这些方法中，用蛋白酶K进行的酶处理被证明最有效。还将介绍高效液相色谱（HPLC）分离策略和电感耦合等离子体质谱（ICP-MS）检测方案。提取物对照市售可得的硒代氨基酸（硒代蛋氨酸（SeMet）、硒代乙硫氨酸（SeEt）和硒代胱氨酸（SeCys））的现有标准进行评估；结果表明，硒代蛋氨酸是这些硒代氨基酸中含量最丰富的。通过采用多种程序，包括电喷雾质谱（ES-MS），尝试对未鉴定的含硒峰进行进一步表征。鉴定出了一种肽结构；然而，由于极其复杂的巴西坚果基质产生的大量背景信号，这被认为是一个初步的推测。
