Synthesis and hyperpolarisation of eNOS substrates for quantification of NO production by 1H-NMR spectrscopy

TY - JOUR

T1 - Synthesis and hyperpolarisation of eNOS substrates for quantification of NO production by 1H-NMR spectrscopy

AU - Diaz-Rullo, Fernando

AU - Zamberlan, Francesco

AU - Mewis, Ryan Edward

AU - Fekete, Marianna

AU - Broche, Lionel

AU - Cheyne, Lesley

AU - Dall’Angelo, Sergio

AU - Duckett, Simon

AU - Dawson, Dana

AU - Zanda, Matteo

N1 - © 2017 The Authors

PY - 2017/3/21

Y1 - 2017/3/21

N2 - Hyperpolarization enhances the intensity of the NMR signals of a molecule, whose in vivo metabolic fate can be monitored by MRI with higher sensitivity. SABRE is a hyperpolarization technique that could potentially be used to image nitric oxide (NO) production in vivo. This would be very important, because NO dysregulation is involved in several pathologies, including cardiovascular ones. The nitric oxide synthase (NOS) pathway leads to NO production via conversion of L-arginine into L-citrulline. NO is a free radical gas with a short half-life in vivo (≈ 5 s), therefore direct NO quantification is challenging. An indirect method – based on quantifying conversion of an L-Arg- to L-Cit-derivative by 1H-NMR spectroscopy – is herein proposed. A small library of pyridyl containing L-Arg derivatives was designed and synthesized. In vitro tests showed that compounds 4a-j and 11a-c were better or equivalent substrates for the eNOS enzyme (NO2- production = 19-46 μM) than native L-Arg (NO2- production = 25 μM). Enzymatic conversion of L-Arg to L-Cit derivatives could be monitored by 1H-NMR. The maximum hyperpolarization achieved by SABRE reached 870-fold NMR signal enhancement, which opens up exciting future perspectives of using these molecules as hyperpolarized MRI tracers in vivo.

AB - Hyperpolarization enhances the intensity of the NMR signals of a molecule, whose in vivo metabolic fate can be monitored by MRI with higher sensitivity. SABRE is a hyperpolarization technique that could potentially be used to image nitric oxide (NO) production in vivo. This would be very important, because NO dysregulation is involved in several pathologies, including cardiovascular ones. The nitric oxide synthase (NOS) pathway leads to NO production via conversion of L-arginine into L-citrulline. NO is a free radical gas with a short half-life in vivo (≈ 5 s), therefore direct NO quantification is challenging. An indirect method – based on quantifying conversion of an L-Arg- to L-Cit-derivative by 1H-NMR spectroscopy – is herein proposed. A small library of pyridyl containing L-Arg derivatives was designed and synthesized. In vitro tests showed that compounds 4a-j and 11a-c were better or equivalent substrates for the eNOS enzyme (NO2- production = 19-46 μM) than native L-Arg (NO2- production = 25 μM). Enzymatic conversion of L-Arg to L-Cit derivatives could be monitored by 1H-NMR. The maximum hyperpolarization achieved by SABRE reached 870-fold NMR signal enhancement, which opens up exciting future perspectives of using these molecules as hyperpolarized MRI tracers in vivo.

M3 - Article

SN - 0968-0896

JO - Bioorganic & Medicinal Chemistry

JF - Bioorganic & Medicinal Chemistry

M1 - BMC_2016_473_R1

ER -