Watermann Stephanie, Schmitt Caroline, Schneider Tobias, Hackl Thomas
Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany.
Hamburg School of Food Science-Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany.
Metabolites. 2021 Jan 8;11(1):39. doi: 10.3390/metabo11010039.
H NMR spectroscopy, in combination with chemometric methods, was used to analyze the methanol/acetonitrile (1:1) extract of walnut ( L.) regarding the geographical origin of 128 authentic samples from different countries (France, Germany, China) and harvest years (2016-2019). Due to the large number of different metabolites within the acetonitrile/methanol extract, the one-dimensional (1D) H NOESY (nuclear Overhauser effect spectroscopy) spectra suffer from strongly overlapping signals. The identification of specific metabolites and statistical analysis are complicated. The use of pure shift H NMR spectra such as PSYCHE (pure shift yielded by chirp excitation) or two-dimensional ASAP-HSQC (acceleration by sharing adjacent polarization-heteronuclear single quantum correlation) spectra for multivariate analysis to determine the geographical origin of foods may be a promising method. Different types of NMR spectra (1D H NOESY, PSYCHE, and ASAP-HSQC) were acquired for each of the 128 walnut samples and the results of the statistical analysis were compared. A support vector machine classifier was applied for differentiation of samples from Germany/China, France/Germany, and France/China. The models obtained by conduction of a repeated nested cross-validation showed accuracies from 58.9% (±1.3%) to 95.9% (±0.8%). The potential of the H-C HSQC as a 2D NMR experiment for metabolomics studies was shown.
采用核磁共振氢谱（¹H NMR）结合化学计量学方法，对核桃（Juglans regia L.）的甲醇/乙腈（1:1）提取物进行分析，该提取物来自不同国家（法国、德国、中国）的128个真实样本以及不同收获年份（2016 - 2019年）。由于乙腈/甲醇提取物中存在大量不同的代谢物，一维（1D）核Overhauser效应光谱（¹H NOESY）谱存在严重的信号重叠。特定代谢物的鉴定和统计分析变得复杂。使用纯位移¹H NMR谱，如PSYCHE（线性调频激发产生的纯位移）或二维ASAP - HSQC（通过共享相邻极化 - 异核单量子相关实现加速）谱进行多变量分析以确定食品的地理来源可能是一种有前景的方法。对128个核桃样本中的每一个都采集了不同类型的NMR谱（1D ¹H NOESY、PSYCHE和ASAP - HSQC），并比较了统计分析结果。应用支持向量机分类器对来自德国/中国、法国/德国和法国/中国的样本进行区分。通过重复嵌套交叉验证得到的模型准确率在58.9%（±1.3%）至95.9%（±0.8%）之间。展示了¹H - ¹³C HSQC作为代谢组学研究的二维NMR实验的潜力。
