Dataset Information

Heterogeneous ¹ H and ¹³ C Parahydrogen-Induced Polarization of Acetate and Pyruvate Esters.

ABSTRACT: Magnetic resonance imaging of [1-¹³ C]hyperpolarized carboxylates (most notably, [1-¹³ C]pyruvate) allows one to visualize abnormal metabolism in tumors and other pathologies. Herein, we investigate the efficiency of ¹ H and ¹³ C 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 1-¹³ C-enriched forms with parahydrogen over Rh/TiO₂ catalysts in methanol-d₄ and in D₂ O. The maximum obtained ¹ H polarization was 0.6±0.2 % (for propyl acetate in CD₃ OD), while the highest ¹³ C polarization was 0.10±0.03 % (for ethyl acetate in CD₃ OD). 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 ¹ H and ¹³ C 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.

SUBMITTER: Salnikov OG

PROVIDER: S-EPMC8249325 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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Publications

Heterogeneous 1 H and 13 C Parahydrogen-Induced Polarization of Acetate and Pyruvate Esters.

Salnikov Oleg G OG Chukanov Nikita V NV Kovtunova Larisa M LM Bukhtiyarov Valerii I VI Kovtunov Kirill V KV Shchepin Roman V RV Koptyug Igor V IV Chekmenev Eduard Y EY

Chemphyschem : a European journal of chemical physics and physical chemistry 20210528 13

Magnetic resonance imaging of [1-13 C]hyperpolarized carboxylates (most notably, [1-13 C]pyruvate) allows one to visualize abnormal metabolism in tumors and other pathologies. Herein, we investigate the efficiency of 1 H and 13 C 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 1-13< ...[more]

PMID: 33929077

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Project description:We report herein a large-scale (>10 g) synthesis of isotopically enriched 1-13C-phosphoenolpyruvate and 1-13C-phosphoenolpyruvate-d2 for application in hyperpolarized imaging technology. The 1-13C-phosphoenolpyruvate-d2 was synthesized with 57% overall yield (over two steps), and >98% 2H isotopic purity, representing an improvement over the previous report. The same outcome was achieved for 1-13C-phosphoenolpyruvate. These two unsaturated compounds with C=C bonds were employed for parahydrogen-induced polarization via pairwise parahydrogen addition in aqueous medium. We find that deuteration of 1-13C-phosphoenolpyruvate resulted in overall increase of 1H T1 of nascent hyperpolarized protons (4.30 ± 0.04 s versus 2.06 ± 0.01 s) and 1H polarization (~2.5% versus ~0.7%) of the resulting hyperpolarized 1-13C-phospholactate. The nuclear spin polarization of nascent parahydrogen-derived protons was transferred to 1-13C nucleus via magnetic field cycling procedure. The proton T1 increase in hyperpolarized deuterated 1-13C-phospholactate yielded approximately 30% better 13C polarization compared to non-deuterated hyperpolarized 1-13C-phospholactate. Analysis of T1 relaxation revealed that deuteration of 1-13C-phospholactate may have resulted in approximately 3-fold worse H→13C polarization transfer efficiency via magnetic field cycling. Since magnetic field cycling is a key polarization transfer step in the Side-Arm Hydrogenation approach, the presented findings may guide more rationale design of contrast agents using parahydrogen polarization of a broad range of 13C hyperpolarized contrast agents for molecular imaging employing 13C MRI. The hyperpolarized 1-13C-phospholactate-d2 is of biomedical imaging relevance because it undergoes in vivo dephosphorylation and becomes 13C hyperpolarized lactate, which as we show can be detected in the brain using 13C hyperpolarized MRI; an implication for future imaging of neurodegenerative diseases and dementia.

Dataset Information

Heterogeneous ¹ H and ¹³ C Parahydrogen-Induced Polarization of Acetate and Pyruvate Esters.

Publications

Heterogeneous <sup>1</sup> H and <sup>13</sup> C Parahydrogen-Induced Polarization of Acetate and Pyruvate Esters.

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