Toward Optimizing and Understanding Reversible Hyperpolarization of Lactate Esters Relayed from para-Hydrogen

The SABRE-Relay hyperpolarization method is used to enhance the H-1 and C-13 NMR signals of lactate esters, which find use in a wide range of medical, pharmaceutical, and food science applications. This is achieved by the indirect relay of magnetization from para- hydrogen, a spin isomer of dihydrogen, to OH-containing lactate esters via a SABRE-hyperpolarized NH intermediary. This delivers H-1 and C-13 NMR signal enhancements as high as 245-and 985-fold, respectively, which makes the lactate esters far more detectable using NMR. DFT-calculated J-couplings and spin dynamics simulations indicate that, while polarization can be transferred from the lactate OH to other H-1 nuclei via the J-coupling network, incoherent mechanisms are needed to polarize the C-13 nuclei at the 6.5 mT transfer field used. The resulting sensitivity boost is predicted to be of great benefit for the NMR detection and quantification of low concentrations (mM) of lactate esters and could provide a useful precursor for the production of hyperpolarized lactate, a key metabolite

Automated summary

The SABRE-Relay hyperpolarization method significantly enhances the NMR signals of lactate esters, making them easier to detect in various applications. By indirectly transferring magnetization from para-hydrogen to OH-containing lactate esters, the method achieves a high sensitivity boost in H-1 and C-13 NMR signal enhancements. This technique has important implications for the detection and quantification of low concentrations of lactate esters and could be used as a precursor for the production of hyperpolarized lactate.