15N hyperpolarisation of the antiprotozoal drug ornidazole by Signal Amplification By Reversible Exchange in aqueous medium. (8th March 2021)

• Record Type: Journal Article
• Authors: Iali, Wissam; Moustafa, Gamal A. I.; Dagys, Laurynas; Roy, Soumya S.
• Other Names: Mewis Ryan E. guestEditor.
• Is Part Of: Magnetic resonance in chemistry. Volume 59:Number 12(2021)
• Page Start: 1199
• Page End: 1207
• Publication Date: 2021-03-08
• Subjects: Nuclear magnetic resonance spectroscopy -- Periodicals; Chemistry, Organic -- Periodicals; Magnetic resonance -- Periodicals; 538.36
• DOI: 10.1002/mrc.5144
• Languages: English
• ISSNs: 0749-1581

Abstract

Abstract: Signal amplification by reversible exchange (SABRE) offers a cost‐effective route to boost nuclear magnetic resonance (NMR) signal by several orders of magnitude by employing readily available para ‐hydrogen as a source of hyperpolarisation. Although 1 H spins have been the natural choice of SABRE hyperpolarisation since its inception due to its simplicity and accessibility, limited spin lifetimes of 1 H makes it harder to employ them in a range of time‐dependent NMR experiments. Heteronuclear spins, for example, 13 C and 15 N, in general have much longer T 1 lifetimes and thereby are found to be more suitable for hyperpolarised biological applications as demonstrated previously by para ‐hydrogen induced polarisation (PHIP) and dynamic nuclear polarisation (DNP). In this study we demonstrate a simple procedure to enhance 15 N signal of an antibiotic drug ornidazole by up to 71, 000‐folds with net 15 N polarisation reaching ~23%. Further, the effect of co‐ligand strategy is studied in conjunction with the optimum field transfer protocols and consequently achieving 15 N hyperpolarised spin lifetime of >3 min at low field. Finally, we present a convenient route to harness the hyperpolarised solution in aqueous medium free from catalyst contamination leading to a strong 15 N signal detection for an extended duration of time. Abstract : A simple experimental route to hyperpolarise natural abundance ornidazole, a routinely used antibiotic, is demonstrated by SABRE hyperpolarisation technique. The co‐ligand effects are studied to optimise the hyperpolarisation effect. A remarkable level of nitrogen‐15 polarisation (23%) is achieved in conjunction with a T 1 lifetime of ~3 min using only 50% enriched para ‐hydrogen. Further, by employing a phase separation approach, we were able to extract hyperpolarised solution of ornidazole in aqueous form with minimal hint of catalyst contamination.