title: Synthesis and hyperpolarisation of eNOS substrates for quantification of NO production by1H NMR spectroscopy.
abstract: 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 (≈5s), therefore direct NO quantification is challenging. An indirect method - based on quantifying conversion of an l-Arg- to l-Cit-derivative by1H NMR spectroscopy - is herein proposed. A small library of pyridyl containing l-Arg derivatives was designed and synthesised. In vitro tests showed that compounds 4a-j and 11a-c were better or equivalent substrates for the eNOS enzyme (NO2-production=19-46μM) than native l-Arg (NO2-production=25μM). Enzymatic conversion of l-Arg to l-Cit derivatives could be monitored by1H 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.
authors.affiliation: Centre for Therapeutics and School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, United Kingdom.
authors.forename: Fernando
authors.initials: F
authors.lastname: Fernandez Diaz-Rullo
authors.affiliation: Centre for Therapeutics and School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, United Kingdom.
authors.forename: Francesco
authors.initials: F
authors.lastname: Zamberlan
authors.affiliation: Centre for Hyperpolarisation in Magnetic Resonance, University of York, Heslington, York YO10 5NY, United Kingdom.
authors.forename: Ryan E
authors.initials: RE
authors.lastname: Mewis
authors.affiliation: Centre for Hyperpolarisation in Magnetic Resonance, University of York, Heslington, York YO10 5NY, United Kingdom.
authors.forename: Marianna
authors.initials: M
authors.lastname: Fekete
authors.affiliation: Centre for Therapeutics and School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, United Kingdom.
authors.forename: Lionel
authors.initials: L
authors.lastname: Broche
authors.affiliation: Centre for Therapeutics and School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, United Kingdom.
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Cheyne
authors.affiliation: Centre for Therapeutics and School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, United Kingdom.
authors.forename: Sergio
authors.initials: S
authors.lastname: Dall'Angelo
authors.affiliation: Centre for Hyperpolarisation in Magnetic Resonance, University of York, Heslington, York YO10 5NY, United Kingdom.
authors.forename: Simon B
authors.initials: SB
authors.lastname: Duckett
authors.affiliation: Centre for Therapeutics and School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, United Kingdom.
authors.forename: Dana
authors.initials: D
authors.lastname: Dawson
authors.affiliation: Centre for Therapeutics and School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB25 2ZD, United Kingdom; C.N.R.- I.C.R.M., via Mancinelli 7, 20131 Milan, Italy. Electronic address: m.zanda@abdn.ac.uk.
authors.forename: Matteo
authors.initials: M
authors.lastname: Zanda
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000378:metabolism; D055162:Biocatalysis; D002417:Cattle; D009682:Magnetic Resonance Spectroscopy; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D013379:Substrate Specificity
chemical_list: D011994:Recombinant Proteins; D009569:Nitric Oxide; D001120:Arginine; D052250:Nitric Oxide Synthase Type III
keywords: Hyperpolarization; MRI; Real-time imaging; SABRE; l-Arginine