Laboratory of Analytical and Bio-Analytical Chemistry, School of Pharmaceutical Sciences, University of Shizuoka , 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
J Agric Food Chem. 2013 Feb 13;61(6):1228-34. doi: 10.1021/jf304822t. Epub 2013 Feb 5.
The presence of specific volatile and aminothiols in wine is associated with quality, worth, price, and taste. The identification of specific thiol-containing compounds in various wines has been reported in many valuable and interesting works. In this study, a novel foodomics assay of thiol-containing compounds, such as free aminothiols and related conjugates, was developed using ultra performance liquid chromatography (UPLC) with fluorescence (FL) and electrospray (ESI) time-of-flight mass spectrometric (TOF/MS) detections. FL specific derivatization was applied along with multivariate statistical analysis. First, the optimal experimental conditions were studied using representative thiols, such as l-cysteine, N-acetyl-l-cysteine, cysteamine, and l-glutathione, and then the UPLC-FL derivatization and separation steps were fixed for the subsequent screening of unknown thiol-containing compounds. The screening assay consisted of monitoring the UPLC-TOF/MS peaks of unknown thiols, which decreased due to the derivatization as compared to the nonderivatized thiols. The principal component analysis of the UPLC-TOF/MS data could be well-differentiated and categorized into two groups. The orthogonal signal correction partial least-squares discriminant analysis, the so-called S-plot, showed that the quality differentiation is directly related to the decrease of native thiols and increase of derivatized thiols. With this strategy, the mass difference from the derivatization reagent (+m/z 198) could be utilized for the identification of these thiols using the FL peaks retention time and metabolomics-databases. The presence of l-glutathione in rice wine was for the first time reported on the basis of the available metabolomics-databases and standard matching. This novel concept based on foodomics could be applied in food analysis for the ready screening of specific functional compounds by exploiting the various derivatization modes available.
葡萄酒中特定挥发性和氨基硫醇的存在与质量、价值、价格和口感有关。在许多有价值和有趣的工作中，已经报道了各种葡萄酒中特定含硫化合物的鉴定。在这项研究中，开发了一种新的基于超高效液相色谱（UPLC）与荧光（FL）和电喷雾（ESI）飞行时间质谱（TOF/MS）检测的含硫化合物（如游离氨基硫醇和相关缀合物）的食品组学分析方法。FL 特异性衍生化与多元统计分析一起应用。首先，使用代表性的硫醇，如 l-半胱氨酸、N-乙酰-l-半胱氨酸、半胱胺和 l-谷胱甘肽，研究了最佳实验条件，然后固定 UPLC-FL 衍生化和分离步骤，用于随后筛选未知含硫化合物。筛选分析包括监测未知含硫化合物的 UPLC-TOF/MS 峰，与未衍生化的硫醇相比，这些峰由于衍生化而减少。UPLC-TOF/MS 数据的主成分分析可以很好地区分和分类为两组。正交信号校正偏最小二乘判别分析，即所谓的 S-图，表明质量差异与天然硫醇的减少和衍生硫醇的增加直接相关。利用该策略，通过衍生化试剂（+m/z 198）的质量差异，可利用 FL 峰保留时间和代谢组学数据库来鉴定这些硫醇。首次基于可用的代谢组学数据库和标准匹配，报道了米酒后 l-谷胱甘肽的存在。这种基于食品组学的新概念可以应用于食品分析中，通过利用各种可用的衍生化模式，对特定功能化合物进行快速筛选。
