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ParaHydrogen Polarized Ethyl‐[1‐ 13 C]pyruvate in Water, a Key Substrate for Fostering the PHIP‐SAH Approach to Metabolic Imaging
Author(s) -
Carrera Carla,
Cavallari Eleonora,
Digilio Giuseppe,
Bondar Oksana,
Aime Silvio,
Reineri Francesca
Publication year - 2021
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202100062
Subject(s) - spin isomers of hydrogen , chemistry , ethyl lactate , catalysis , hyperpolarization (physics) , photochemistry , medicinal chemistry , nuclear magnetic resonance spectroscopy , stereochemistry , organic chemistry , hydrogen
Abstract An efficient synthesis of vinyl‐[1‐ 13 C]pyruvate has been reported, from which 13 C hyperpolarized (HP) ethyl‐[1‐ 13 C]pyruvate has been obtained by means of ParaHydrogen Induced Polarization (PHIP). Due to the intrinsic lability of pyruvate, which leads quickly to degradation of the reaction mixture even under mild reaction conditions, the vinyl‐ester has been synthesized through the intermediacy of a more stable ketal derivative. 13 C and 1 H hyperpolarizations of ethyl‐[1‐ 13 C]pyruvate, hydrogenated using ParaHydrogen, have been compared to those observed on the more widely used allyl‐derivative. It has been demonstrated that the spin order transfer from ParaHydrogen protons to 13 C, is more efficient on the ethyl than on the allyl‐esterdue to the larger J‐couplings involved. The main requirements needed for the biological application of this HP product have been met, i. e. an aqueous solution of the product at high concentration (40 mM) with a good 13 C polarization level (4.8 %) has been obtained. The in vitro metabolic transformation of the HP ethyl‐[1‐ 13 C]pyruvate, catalyzed by an esterase, has been observed. This substrate appears to be a good candidate for in vivo metabolic investigations using PHIP hyperpolarized probes.