Nuclear hyperpolarization of (1-13C)-pyruvate in aqueous solution by proton-relayed side-arm hydrogenation

We employ Parahydrogen Induced Polarization with Side-Arm Hydrogenation (PHIP-SAH) to polarize (1-C-13)-pyruvate. We introduce a new method called proton-relayed side-arm hydrogenation (PR-SAH) in which an intermediate proton is used to transfer polarization from the side-arm to the C-13-labelled site of the pyruvate before hydrolysis. This significantly reduces the cost and effort needed to prepare the precursor for radio-frequency transfer experiments while still maintaining acceptable polarization transfer efficiency. Experimentally we have attained on average 4.33% C-13 polarization in an aqueous solution of (1-C-13)-pyruvate after about 10 seconds of cleavage and extraction. PR-SAH is a promising pulsed NMR method for hyperpolarizing C-13-labelled metabolites in solution, conducted entirely in high magnetic field.

Automated summary

The study introduces a new method, PR-SAH, which reduces the cost and effort needed to prepare the precursor by using an intermediate proton to transfer polarization from the side-arm to the C-13-labelled site of the pyruvate. This method shows promise in hyperpolarizing C-13-labelled metabolites in solution, conducted entirely in high magnetic field.