by Keyword: Fumarates
Eills, James, Picazo-Frutos, Roman, Bondar, Oksana, Cavallari, Eleonora, Carrera, Carla, Barker, Sylwia J, Utz, Marcel, Herrero-Gomez, Alba, Marco-Rius, Irene, Tayler, Michael C D, Aime, Silvio, Reineri, Francesca, Budker, Dmitry, Blanchard, John W, (2023). Enzymatic Reactions Observed with Zero- and Low-Field Nuclear Magnetic Resonance Analytical Chemistry 95, 17997-18005 
We demonstrate that enzyme-catalyzed reactions can be observed in zero- and low-field NMR experiments by combining recent advances in parahydrogen-based hyperpolarization methods with state-of-the-art magnetometry. Specifically, we investigated two model biological processes: the conversion of fumarate into malate, which is used in vivo as a marker of cell necrosis, and the conversion of pyruvate into lactate, which is the most widely studied metabolic process in hyperpolarization-enhanced imaging. In addition to this, we constructed a microfluidic zero-field NMR setup to perform experiments on microliter-scale samples of [1-C-13]-fumarate in a lab-on-a-chip device. Zero- to ultralow-field (ZULF) NMR has two key advantages over high-field NMR: the signals can pass through conductive materials (e.g., metals), and line broadening from sample heterogeneity is negligible. To date, the use of ZULF NMR for process monitoring has been limited to studying hydrogenation reactions. In this work, we demonstrate this emerging analytical technique for more general reaction monitoring and compare zero- vs low-field detection.
JTD Keywords: Fumarates, Hydrogenation, Magnetic resonance imaging, Magnetic resonance spectroscopy, Nmr j-spectroscopy, Pyruvic acid
Gierse, M, Nagel, L, Keim, M, Lucas, S, Speidel, T, Lobmeyer, T, Winter, G, Josten, F, Karaali, S, Fellermann, M, Scheuer, J, Müller, C, van Heijster, F, Skinner, J, Löffler, J, Parker, A, Handwerker, J, Marshall, A, Salhov, A, El-Kassem, B, Vassiliou, C, Blanchard, JW, Picazo-Frutos, R, Eills, J, Barth, H, Jelezko, F, Rasche, V, Schilling, F, Schwartz, I, Knecht, S, (2023). Parahydrogen-Polarized Fumarate for Preclinical in Vivo Metabolic Magnetic Resonance Imaging Journal Of The American Chemical Society 145, 5960-5969
We present a versatile method for the preparation of hyperpolarized [1-13C]fumarate as a contrast agent for preclinical in vivo MRI, using parahydrogen-induced polarization (PHIP). To benchmark this process, we compared a prototype PHIP polarizer to a state-of-the-art dissolution dynamic nuclear polarization (d-DNP) system. We found comparable polarization, volume, and concentration levels of the prepared solutions, while the preparation effort is significantly lower for the PHIP process, which can provide a preclinical dose every 10 min, opposed to around 90 min for d-DNP systems. With our approach, a 100 mM [1-13C]-fumarate solution of volumes up to 3 mL with 13-20% 13C-hyperpolarization after purification can be produced. The purified solution has a physiological pH, while the catalyst, the reaction side products, and the precursor material concentrations are reduced to nontoxic levels, as confirmed in a panel of cytotoxicity studies. The in vivo usage of the hyperpolarized fumarate as a perfusion agent in healthy mice and the metabolic conversion of fumarate to malate in tumor-bearing mice developing regions with necrotic cell death is demonstrated. Furthermore, we present a one-step synthesis to produce the 13C-labeled precursor for the hydrogenation reaction with high yield, starting from 13CO2 as a cost-effective source for 13C-labeled compounds.
JTD Keywords: Animals, Contrast media, Fumarates, Hydrogenation, Magnetic resonance imaging, Magnetic resonance spectroscopy, Mice, Para-hydrogen
