¹³C MR Hyperpolarization of Lactate by Using ParaHydrogen and Metabolic Transformation in Vitro

Abstract

Abstract:Hyperpolarization of the 13C magnetic resonance signal of L-[1-13C]Lactate has been obtained using the chemically based, cost-effective method named ParaHydrogen Induced Polarization by means of Side Arm Hydrogenation (PHIP-SAH). Two ester derivatives of lactate have been tested and the factors that determine the polarization level on the product have been investigated into details. The metabolic conversion of hyperpolarized L-[1-13C]Lactate into Pyruvate has been observed in vitro using lactate dehydrogenase (LDH) and in a cells lysate. From the acquisition of a series of 13C-NMR spectra, the metabolic build-up of the [1-13C]Pyruvate signal has been observed. These studies demonstrate that, even if the experimental set-up used for these PHIP-SAH hyperpolarization studies is still far from optimal, the attained polarization level is already sufficient to carry out in vitro metabolic studies.Author Comments: Dear editor, enclosed please find the manuscript entitled "13C-MR Hyperpolarization of Lactate using ParaHydrogen and metabolic transformation in vitro " to be considered for publication in Chemistry, a European Journal. A previous version of the manuscript had been submitted to this journal and one of the two referees evaluated it a highly important manuscript, while the other considered it too specialized for publication, than the manuscript was rejected. Nevertheless, the editor suggested that an appropriately supplemented manuscript should be reconsidered.Here is submitted a deeply revised version of the manuscript. New experiments have been added, in accordance with the reviewers' suggestions, and new results have been obtained. The whole text has been extensively edited and integrated. We hope that, with the integration of the new results, the manuscript will be considered worth of publication in Chemistry. C]Pyruvate signal has been observed. These studies demonstrate that, even if the experimental set-up used for these PHIP-SAH hyperpolarization studies is still far from optimal, the attained polarization level is already sufficient to carry out in vitro metabolic studies. Yours sincerely Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation

Signal Amplification by Reversible Exchange (SABRE): From Discovery to Diagnosis

“…[5] An alternative and simple route to nuclear spin polarization involves the addition of singlet-state-based parahydrogen (p-H 2 )t oa nu nsaturated center, collectively termed parahydrogen-induced polarization (PHIP). [8] In 2009, the PHIP technique termed signal amplification by reversible exchange (SABRE) allowed access to hyperpolarized substrates without changing their chemical identity. [7] Recently,t he use of cleavable,u nsaturated molecular tags, including propargyl esters,h as broadened the scope of the PHIP method to include access to pyruvate,acetate,and even lactate for the monitoring of metabolism in vitro.…”

Metabolic Studies of Tumor Cells Using [1‐13C] Pyruvate Hyperpolarized by Means of PHIP‐Side Arm Hydrogenation

“…The transfer of the parahydrogen spin order to 13 C net magnetization takes place though very small, long range J‐couplings and this transfer is efficiently pursued by means of a properly designed magnetic field cycle (MFC), i. e. a polarization transfer method that can facilitate hyperpolarization transfer through long distance spins . The PHIP‐SAH method appears of general applicability and it has been successfully tested to obtain 13 C HP acetate, [1‐ 13 C]lactate and [1‐ 13 C]‐pyruvate.…”

Over 50 % 1H and 13C Polarization for Generating Hyperpolarized Metabolites—A para‐Hydrogen Approach

“…Cleavage of the precursor molecule leads to hyperpolarized metabolites. In the case of lactate, it was demonstrated that, after the polarization procedure, lactate can enzymatically be converted into pyruvate . So far, the most successful approach of hyperpolarizing metabolites with para ‐hydrogen relies on a field cycling technique, for which 13 C polarization values of about 5 % have been experimentally demonstrated in highly concentrated solutions of acetate and pyruvate .…”