Developing Analytical Applications for Parahydrogen Hyperpolarization: Urinary Elimination Pharmacokinetics of Nicotine

Abstract

Nuclear magnetic resonance spectroscopy (NMR) is a valuable analytical tool with applications in a vast array of research fields from chemistry and biology to medicine and beyond. NMR is renowned for its straightforward data interpretation and quantitative properties, making it attractive for pharmacokinetic applications, where drug metabolism pathways, concentrations, and kinetics need to be evaluated. However, pharmacologically active compounds and their metabolites in biofluids often appear in minute concentrations, well below the detection limit of NMR. Herein, we demonstrate how parahydrogen hyperpolarization overcomes this sensitivity barrier, allowing us to detect mid-nanomolar concentrations of a drug and a drug metabolite in a biofluid matrix. The performance of the method is demonstrated by monitoring nicotine and cotinine urinary elimination, reflected by their concentrations in urine during the onset and withdrawal from nicotine consumption. An NMR limit of detection of 0.1 μM and a limit of quantitation of 0.7 μM is achieved in a practical pharmacokinetics scenario where precise quantitative and qualitative analysis is desired.

Human metabolite detection by surface-enhanced Raman spectroscopy

“…The benefits and shortcomings of MS and NMR are listed in Table 1 . Nevertheless, limited by relatively low sensitivity, NMR is only appliable for metabolites of adequate concentrations [ 52 ].…”

Understanding Parahydrogen Hyperpolarized Urine Spectra: The Case of Adenosine Derivatives

“…Signals of structurally similar analytes have been found to form linear patterns in the 2D ZQ plots ([6] and Figure 2). These patterns aid identification [6,9] but the physical explanation for their formation has not been described yet. Analyte scope of the method is limited by its chemoselectivity, making it less universal than traditional NMR as it detects only analytes capable of binding to 2.…”

“…Signal assignment is arguably the most notable limitation hindering wider adoption of the technique. Since hydride signals do not carry as much structural information as traditional NMR, the only reliable way of assigning signals has proven to be internal standard addition [4,7,9]. The most practical pulse sequence for hyperpolarized chemosensing [6], which can also be carried out as very fast experiments [20], resolves hydride signals (red in Figure 1) according to their mutual zero quantum (ZQ) frequency in the indirect dimension of 2D spectra.…”

“…10 ppm region [4]. Furthermore, the complexity of published hyperpolarized urine spectra [6][7][8][9] demonstrates that even the catalyst's limited chemical scope allows for the detection of large numbers of metabolites. The list of known 2 binding analytes is growing and includes, on top of nitrogenous heteroaromatics, pyruvate [10], tagged oligopeptides [11,12], amino acids [13,14], nitriles [15], and sulfur heteroaromatics [16], suggesting the chemoselectivity envelope is wide.…”

Parahydrogen Hyperpolarization Allows Direct NMR Detection of α‐Amino Acids in Complex (Bio)mixtures

“…NhPHIP-NMR chemosensing is based on the reversible binding of substrates to ac omplex of iridium with an Nheterocyclic carbene ligand, such as the Ir-IMes catalyst, together with p-H 2 and asuitable co-substrate,asillustrated in Figure 1. [28][29][30] Formation of these transient asymmetric complexes at high magnetic field allows the conversion of the singlet state originating from p-H 2 to hydrides magnetization that can be detected via NMR with enhanced sensitivity.W e have previously shown that the hydrides chemical shifts are highly sensitive to the structure of the analyte associating to the iridium complex and, therefore,can act as hyperpolarized probes to reveal the presence of specific substrates in the sample. [29] Thesame approach can be applied to detect most a-amino acids with enhanced NMR sensitivity.I twas previously demonstrated that these compounds can bind to iridium catalysts as bidentate ligands,v ia their amino-and carboxy groups.…”