@article{GentzschChenSpatzetal.2021,
  author    = {Gentzsch, Christian and Chen, Xinyu and Spatz, Philipp and Košak, Urban and Knez, Damijan and Nose, Naoko and Gobec, Stanislav and Higuchi, Takahiro and Decker, Michael},
  title     = {Synthesis and Initial Characterization of a Reversible, Selective \(^{18}\)F-Labeled Radiotracer for Human Butyrylcholinesterase},
  series = {Molecular Imaging and Biology},
  volume    = {23},
  journal   = {Molecular Imaging and Biology},
  number    = {4},
  issn      = {1860-2002},
  doi       = {10.1007/s11307-021-01584-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-269870},
  pages     = {505-515},
  year      = {2021},
  abstract  = {Purpose A neuropathological hallmark of Alzheimer's disease (AD) is the presence of amyloid-β (Aβ) plaques in the brain, which are observed in a significant number of cognitively normal, older adults as well. In AD, butyrylcholinesterase (BChE) becomes associated with A\(_{β}\) aggregates, making it a promising target for imaging probes to support diagnosis of AD. In this study, we present the synthesis, radiochemistry, in vitro and preliminary ex and in vivo investigations of a selective, reversible BChE inhibitor as PET-tracer for evaluation as an AD diagnostic. Procedures Radiolabeling of the inhibitor was achieved by fluorination of a respective tosylated precursor using K[\(^{18}\)F]. IC\(_{50}\) values of the fluorinated compound were obtained in a colorimetric assay using recombinant, human (h) BChE. Dissociation constants were determined by measuring hBChE activity in the presence of different concentrations of inhibitor. Results Radiofluorination of the tosylate precursor gave the desired radiotracer in an average radiochemical yield of 20 ± 3 \%. Identity and > 95.5 \% radiochemical purity were confirmed by HPLC and TLC autoradiography. The inhibitory potency determined in Ellman's assay gave an IC\(_{50}\) value of 118.3 ± 19.6 nM. Dissociation constants measured in kinetic experiments revealed lower affinity of the inhibitor for binding to the acylated enzyme (K2 = 68.0 nM) in comparison to the free enzyme (K\(_{1}\) = 32.9 nM). Conclusions The reversibly acting, selective radiotracer is synthetically easily accessible and retains promising activity and binding potential on hBChE. Radiosynthesis with \(^{18}\)F labeling of tosylates was feasible in a reasonable time frame and good radiochemical yield.},
  language  = {en}
}
@article{GentzschHoffmannOhshimaetal.2021,
  author    = {Gentzsch, Christian and Hoffmann, Matthias and Ohshima, Yasuhiro and Nose, Naoko and Chen, Xinyu and Higuchi, Takahiro and Decker, Michael},
  title     = {Synthesis and Initial Characterization of a Selective, Pseudo-irreversible Inhibitor of Human Butyrylcholinesterase as PET Tracer},
  series = {ChemMedChem},
  volume    = {16},
  journal   = {ChemMedChem},
  number    = {9},
  doi       = {10.1002/cmdc.202000942},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239904},
  pages     = {1427 -- 1437},
  year      = {2021},
  abstract  = {The enzyme butyrylcholinesterase (BChE) represents a promising target for imaging probes to potentially enable early diagnosis of neurodegenerative diseases like Alzheimer's disease (AD) and to monitor disease progression in some forms of cancer. In this study, we present the design, facile synthesis, in vitro and preliminary ex vivo and in vivo evaluation of a morpholine-based, selective inhibitor of human BChE as a positron emission tomography (PET) tracer with a pseudo-irreversible binding mode. We demonstrate a novel protecting group strategy for 18F radiolabeling of carbamate precursors and show that the inhibitory potency as well as kinetic properties of our unlabeled reference compound were retained in comparison to the parent compound. In particular, the prolonged duration of enzyme inhibition of such a morpholinocarbamate motivated us to design a PET tracer, possibly enabling a precise mapping of BChE distribution.},
  language  = {en}
}
@phdthesis{Gentzsch2021,
  author    = {Gentzsch, Christian},
  title     = {Molecular Imaging of Opioid Receptors and Butyrylcholinesterase with Selective, Tailored Probes Using Positron Emission Tomography and Fluorescence Microscopy},
  doi       = {10.25972/OPUS-24752},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-247529},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The present thesis concerns the molecular imaging of opioid receptors and human butyrylcholinesterase with the aid of tailored probes, which are suitable for the respective applied imaging techniques. The first part focusses on imaging of opioid receptors with selective probes using total internal reflection- and single molecule fluorescence microscopy. Design and synthesis of the ligands are presented and their pharmacological characterization and application in microscopy experiments are shown. The second part of this thesis focused on the development of 18F-labeled, selective radiotracers for imaging of butyrylcholinesterase via positron emission tomography. The design and synthesis of each a reversible and pseudoirreversible 18F-labeled tracer are presented. After evaluation of the binding properties of each tracer, their initial application in ex vivo autoradiography- and preliminary in vivo microPET studies is described and analyzed.},
  subject      = {Fluoreszenzmikroskopie},
  language  = {en}
}