NMR is a central tool in the field of metabolomics, thanks to its ability to provide valuable structural and quantitative information with high precision. Most NMR-based metabolomics studies rely on 1D ¹H detection, which is heavily limited by strong peak overlap. ¹³C NMR benefits from a wider spectral dispersion and narrower signal line width but is barely used in metabolomics due to its low sensitivity. Dissolution dynamic nuclear polarization (d-DNP) offers an opportunity to improve ¹³C NMR sensitivity by several orders of magnitude. Here, we show that this emerging hyperpolarized metabolomics approach can provide meaningful information about clinical samples. Achieving sub-mM limits of detection with ¹³C at natural abundance in urine samples was made possible by a meticulous design of the experimental workflow. The analysis of human urine samples from patients with different stages of chronic kidney disease (CKD) was performed using ¹³C d-DNP NMR and benchmarked to conventional ¹H NMR metabolomics at a high magnetic field to explore the complementarity between the two methods. Multivariate analysis of the d-DNP ¹³C NMR dataset provided a statistical model able to distinguish patients with CKD from control patients. Moreover, ¹³C d-DNP NMR spectra highlighted several biomarkers known to be biologically relevant. Some of them were in agreement with those obtained with conventional ¹H NMR, and the results also highlighted the complementarity of biomarker coverage between hyperpolarized and conventional NMR metabolomics. In particular, ¹³C hyperpolarized NMR allowed the annotation of two biomarkers that could not be detected by ¹H NMR because of peak overlap (i.e., guanine and guanidoacetate).

中文翻译：

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自然丰度尿液样本的超极化 13C NMR 代谢组学应用于慢性肾病


NMR 是代谢组学领域的核心工具，因为它能够高精度地提供有价值的结构和定量信息。大多数基于 NMR 的代谢组学研究依赖于 1D ¹H 检测，这在很大程度上受到强峰重叠的限制。¹³C NMR 受益于更宽的光谱色散和更窄的信号线宽度，但由于灵敏度低，几乎不用于代谢组学。溶出动态核极化 （d-DNP） 为将 ¹³C NMR 灵敏度提高了几个数量级提供了机会。在这里，我们表明这种新兴的超极化代谢组学方法可以提供有关临床样本的有意义信息。通过精心设计的实验工作流程，尿液样品中自然丰度为 ¹³C 时可实现亚 mM 检测限。使用 ¹³C d-DNP NMR 对不同阶段慢性肾脏病 （CKD） 患者的人尿液样本进行分析，并在高磁场下与传统的 ¹H NMR 代谢组学进行基准测试，以探索两种方法之间的互补性。d-DNP ¹³C NMR 数据集的多变量分析提供了一个能够区分 CKD 患者和对照患者的统计模型。此外，¹³C d-DNP NMR 波谱突出了几种已知具有生物学相关性的生物标志物。其中一些与常规 ¹H NMR 获得的一致，结果还强调了超极化和常规 NMR 代谢组学之间生物标志物覆盖率的互补性。 特别是，¹³C 超极化 NMR 允许注释由于峰重叠而无法被 ¹H NMR 检测到的两种生物标志物（即鸟嘌呤和胍基乙酸）。