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

Hyperpolarization of the C-13 magnetic resonance signal of L-[1-C-13] lactate has been obtained using the chemically based, cost-effective method called parahydrogen-induced polarization by means of side-arm hydrogenation (PHIP-SAH). Two ester derivatives of lactate were tested and the factors that determine the polarization level on the product have been investigated in detail. The metabolic conversion of hyperpolarized L-[1-C-13] lactate into pyruvate has been observed in vitro using lactate dehydrogenase (LDH) and in a cells lysate. From the acquisition of a series of C-13 NMR spectra, the metabolic build-up of the [1-C-13] 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.