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Over 20% 15N Hyperpolarization in Under One Minute for Metronidazole, an Antibiotic and Hypoxia Probe

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journal contribution
posted on 20.06.2016, 00:00 by Danila A. Barskiy, Roman V. Shchepin, Aaron M. Coffey, Thomas Theis, Warren S. Warren, Boyd M. Goodson, Eduard Y. Chekmenev
Direct NMR hyperpolarization of naturally abundant 15N sites in metro­nid­azole is demonstrated using SABRE-SHEATH (Signal Amplification by Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei). In only a few tens of seconds, nuclear spin polarization P15N of up to ∼24% is achieved using parahydrogen with 80% para fraction corresponding to P15N ≈ 32% if ∼100% parahydrogen were employed (which would translate to a signal enhancement of ∼0.1-million-fold at 9.4 T). In addition to this demonstration on the directly binding 15N site (using J2H‑15N), we also hyperpolarized more distant 15N sites in metro­nid­azole using longer-range spin–spin couplings (J4H‑15N and J5H‑15N). Taken together, these results significantly expand the range of molecular structures and sites amenable to hyperpolarization via low-cost parahydrogen-based methods. In particular, hyperpolarized nitro­imid­azole and its derivatives have powerful potential applications such as direct in vivo imaging of mechanisms of action or hypoxia sensing.