title: Parahydrogen induced polarization in face of keto-enol tautomerism: proof of concept with hyperpolarized ethanol.
abstract: Hyperpolarization (HP) techniques are increasingly important in magnetic resonance imaging (MRI) and spectroscopy (MRS). HP methods have the potential to overcome the fundamentally low sensitivity of magnetic resonance (MR). A breakthrough of HP-MR in life sciences and medical applications is still limited by the small number of accessible, physiologically relevant substrates. Our study presents a new approach to extend PHIP to substrates that primarily cannot be hyperpolarized due to a steady intramolecular re-arrangement, the so-called keto-enol tautomerism. To overcome this obstacle we exploited the fact that instead of the instable enol form the corresponding stable ester can be used as a precursor molecule. This strategy now enables the hydrogenation which is required to apply the standard PHIP procedure. As the final step a hydrolysis is necessary to release the hyperpolarized target molecule. Using this new approach ethanol was successfully hyperpolarized for the first time. It may therefore be assumed that the outlined multi-step procedure can be used for other keto-enol tautomerized substances thereby opening the application of PHIP to a multitude of molecules relevant to analyzing metabolic pathways.
authors.affiliation: Dept. for Biometry and Medical Informatics, Otto-von-Guericke-University Magdeburg, Germany. thomas.trantzschel@med.ovgu.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Trantzschel
authors.forename: Johannes
authors.initials: J
authors.lastname: Bernarding
authors.forename: Markus
authors.initials: M
authors.lastname: Plaumann
authors.forename: Denise
authors.initials: D
authors.lastname: Lego
authors.forename: Torsten
authors.initials: T
authors.lastname: Gutmann
authors.forename: Tomasz
authors.initials: T
authors.lastname: Ratajczyk
authors.forename: Sonja
authors.initials: S
authors.lastname: Dillenberger
authors.forename: Gerd
authors.initials: G
authors.lastname: Buntkowsky
authors.forename: Joachim
authors.initials: J
authors.lastname: Bargon
authors.forename: Ute
authors.initials: U
authors.lastname: Bommerich
mesh_terms: D000431:Ethanol / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D007659:Ketones; D000431:Ethanol; D006859:Hydrogen