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Heterogeneous 1H and 13C Parahydrogen-Induced Polarization of Acetate and Pyruvate Esters |
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| Authors: | Dr Oleg G Salnikov Dr Nikita V Chukanov Dr Larisa M Kovtunova Prof Valerii I Bukhtiyarov Dr Kirill V Kovtunov Prof Roman V Shchepin Prof Igor V Koptyug Prof Eduard Y Chekmenev |
| Institution: | 1. International Tomography Center SB RAS, 3?A Institutskaya St., 630090 Novosibirsk, Russia;2. International Tomography Center SB RAS, 3?A Institutskaya St., 630090 Novosibirsk, Russia
Boreskov Institute of Catalysis SB RAS, 5 Acad. Lavrentiev Pr., 630090 Novosibirsk, Russia Department of Natural Sciences, Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russia;3. Boreskov Institute of Catalysis SB RAS, 5 Acad. Lavrentiev Pr., 630090 Novosibirsk, Russia Department of Natural Sciences, Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russia;4. International Tomography Center SB RAS, 3?A Institutskaya St., 630090 Novosibirsk, Russia Department of Natural Sciences, Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russia Deceased;5. Department of Chemistry, Biology, and Health Sciences, South Dakota School of Mines & Technology, 57701 Rapid City, South Dakota, United States;6. Department of Chemistry, Integrative Biosciences (Ibio), Karmanos Cancer Institute (KCI), Wayne State University, 48202 Detroit, Michigan, United States |
| Abstract: | Magnetic resonance imaging of 1-13C]hyperpolarized carboxylates (most notably, 1-13C]pyruvate) allows one to visualize abnormal metabolism in tumors and other pathologies. Herein, we investigate the efficiency of 1H and 13C hyperpolarization of acetate and pyruvate esters with ethyl, propyl and allyl alcoholic moieties using heterogeneous hydrogenation of corresponding vinyl, allyl and propargyl precursors in isotopically unlabeled and 1-13C-enriched forms with parahydrogen over Rh/TiO2 catalysts in methanol-d4 and in D2O. The maximum obtained 1H polarization was 0.6±0.2 % (for propyl acetate in CD3OD), while the highest 13C polarization was 0.10±0.03 % (for ethyl acetate in CD3OD). Hyperpolarization of acetate esters surpassed that of pyruvates, while esters with a triple carbon-carbon bond in unsaturated alcoholic moiety were less efficient as parahydrogen-induced polarization precursors than esters with a double bond. Among the compounds studied, the maximum 1H and 13C NMR signal intensities were observed for propyl acetate. Ethyl acetate yielded slightly less intense NMR signals which were dramatically greater than those of other esters under study. |
| Keywords: | parahydrogen hyperpolarization PHIP NMR spectroscopy imaging agents |