Entwicklung und Synthese potenzieller allosterischer Modulatoren ausgewählter G-Protein gekoppelter Rezeptoren sowie potenzieller Inhibitoren des eukaryotischen Initiationsfaktors 4A
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Philipps-Universität Marburg
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This work is divided into three different parts. In the first part of this thesis potential allosteric ligands were synthesized to address one of the following G-protein coupled receptors (GPCRs): Endothelin B-, free fatty acid 3-receptor or the orphan receptor GPRC5B. GPCRs represent one of the largest protein families with more than 800 members. Consisting of a seven transmembrane domain they couple to different Gα-proteins on their intracellular side. Furthermore, they are targeted by a variety of different endogenous ligands and therefore are involved in various physiological processes, making them an interesting drug target for several diseases. More than 30 percent of the approved drugs target GPCRs. However, the development of selective ligands is challenging due to their highly conserved orthosteric binding side within a receptor family. Hence, identification as well as targeting alternative and less conserved binding pockets with allosteric modulators could provide selective ligands causing less undesired side effects. As part of the GLUE-project (G-protein coupled receptor ligands for underexplored epitopes) the group of Prof. Kolb identified promising ligands with in silico docking methods. Based on the evaluation of the docking poses and the synthetic accessibility the most promising molecules were selected for synthesis. Overall, 110 compounds were synthesized based on 10 different base structures out of four docking studies performed by the group of Prof. Kolb and an own de novo approach. 86 of these compounds should target the G-protein binding pocket of ETBR, while 7 compounds should address the known site 5 (KS5). Additionally, two already known allosteric modulators and two derivatives were synthesized. All synthesized derivatives were analytically characterized and tested afterwards in the group of Prof. Bünemann. Using FRET-based methods the compounds were tested in a G-protein binding and a receptor sensor assay at an initial concentration of 100 μM on the ETBR and the FFAR3. None of the tested compounds has shown a biological activity in the performed assays. The last 13 compounds were synthesized to address the orphan receptor GPRC5B. Due to the lack of a suitable assay these 13 compounds were not tested for their biological activity so far.
In the second part of this thesis the focus was to design and synthesize potential inhibitors for the eucaryotic initiation factor 4A (eIF4A). The RNA-helicase eIF4A is involved in the initiation process of the translation by unwinding secondary structures within the 5’-UTR of a mRNA and therefore enabling protein synthesis. Due to their lack of an own mechanism for protein synthesis viruses are dependent on the mechanism of their host, making eIF4A a suitable target for potential host-targeting antivirals. Based on a benzoxazole-fragment designed by H. Kutzner (group of Prof. Schlitzer) the aim of this work was to address arginine-residues in the binding pocket by adding polar groups. Therefore 27 different benzoxazole-derivatives with a modified base structure or an additional polar residue were synthesized. All compounds were then tested in the group of Prof. Grünweller in a thermal shift assay. All synthesized compounds had shown a positive thermal shift suggesting the binding to eIF4A. The most promising compound containing a polar residue was selected to be tested in a Dual Luciferase assay to determine the potential of reducing the translation efficiency. Unfortunately, this assay could not be performed due to a bacterial contamination of the selected compound.
In the third part of this work derivatives of a piperazine-containing anthranilic amide originally designed by S. Heinrich (group of Prof. Schlitzer) were synthesized as potential anthelmintics against Schistosoma mansoni. Schistosomiasis is a parasitic disease which is caused by blood flukes of the genus Schistosoma. It is endemic in 78 countries in tropical and subtropical regions and at least 230 million people need preventive treatment annually. The treatment relies mainly on praziquantel, so new antischistosomal drugs are required. The original piperazine-containing compounds designed by S. Heinrich were developed for Plasmodium falciparum and were tested for their antischistosomal potential as part of this work. Besides the synthesis of two compounds from S. Heinrich additional four derivatives were designed and synthesized. The compounds were tested in collaboration with the group of Prof. Grevelding by Dr. T. Gallinger (group of Prof. Schlitzer) against S. mansoni at 25 μM. Only the two original compounds had shown antischistosomal activity but were also cytotoxic at these concentrations, so a further development was not taken into consideration.
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Created: 2024Issued: 2024-12-09Updated: 2024-12-09
Faculty
Fachbereich Pharmazie
Publisher
Philipps-Universität Marburg
Language
ger
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DoctoralThesis
DFG-subjects
Chemiemedizinische ChemieSyntheseorganische ChemieHelikaseGPCRseIF4A
DDC-Numbers
540
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Klüppel, Maike: Entwicklung und Synthese potenzieller allosterischer Modulatoren ausgewählter G-Protein gekoppelter Rezeptoren sowie potenzieller Inhibitoren des eukaryotischen Initiationsfaktors 4A. : Philipps-Universität Marburg 2024-12-09. DOI: https://doi.org/10.17192/z2024.0495.