• Design and synthesis of a library of lead-like 2,4-bisheterocyclic substituted thiophenes as selective Dyrk/Clk inhibitors.

      Schmitt, Christian; Kail, Dagmar; Mariano, Marica; Empting, Martin; Weber, Nadja; Paul, Tamara; Hartmann, Rolf W.; Engel, Matthias; Helmholtz Institute für Pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2014)
      The Dyrk family of protein kinases is implicated in the pathogenesis of several diseases, including cancer and neurodegeneration. Pharmacological inhibitors were mainly described for Dyrk1A so far, but in fewer cases for Dyrk1B, Dyrk2 or other isoforms. Herein, we report the development and optimization of 2,4-bisheterocyclic substituted thiophenes as a novel class of Dyrk inhibitors. The optimized hit compounds displayed favorable pharmacokinetic properties and high ligand efficiencies, and inhibited Dyrk1B in intact cells. In a larger selectivity screen, only Clk1 and Clk4 were identified as additional targets of compound 48, but no other kinases frequently reported as off-targets. Interestingly, Dyrk1A is implicated in the regulation of alternative splicing, a function shared with Clk1/Clk4; thus, some of the dual inhibitors might be useful as efficient splicing modulators. A further compound (29) inhibited Dyrk1A and 1B with an IC50 of 130 nM, showing a moderate selectivity over Dyrk2. Since penetration of the central nervous system (CNS) seems possible based on the physicochemical properties, this compound might serve as a lead for the development of potential therapeutic agents against glioblastoma. Furthermore, an inhibitor selective for Dyrk2 (24) was also identified, which might be are suitable as a pharmacological tool to dissect Dyrk2 isoform-mediated functions.
    • Dynamic Combinatorial Chemistry to Identify Binders of ThiT, an S-Component of the Energy-Coupling Factor Transporter for Thiamine.

      Monjas, Leticia; Swier, Lotteke J Y M; Setyawati, Inda; Slotboom, Dirk J; Hirsch, Anna K H; Helmholtz-Institut für pharmazeutische Forschung Saarland, Universitätscampus E9.1, 66123 Saarbrücken, Germany. (2017-10-20)
      We applied dynamic combinatorial chemistry (DCC) to identify ligands of ThiT, the S-component of the energy-coupling factor (ECF) transporter for thiamine in Lactococcus lactis. We used a pre-equilibrated dynamic combinatorial library (DCL) and saturation-transfer difference (STD) NMR spectroscopy to identify ligands of ThiT. This is the first report in which DCC is used for fragment growing to an ill-defined pocket, and one of the first reports for its application with an integral membrane protein as target.
    • Structural basis for species specific inhibition of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1): computational study and biological validation.

      Klein, Tobias; Henn, Claudia; Negri, Matthias; Frotscher, Martin; Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, Germany. (2011)
      17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) catalyzes the reduction of estrone to estradiol, which is the most potent estrogen in humans. Inhibition of 17β-HSD1 and thereby reducing the intracellular estradiol concentration is thus a promising approach for the treatment of estrogen dependent diseases. In the past, several steroidal and non-steroidal inhibitors of 17β-HSD1 have been described but so far there is no cocrystal structure of the latter in complex with 17β-HSD1. However, a distinct knowledge of active site topologies and protein-ligand interactions is a prerequisite for structure-based drug design and optimization. An elegant strategy to enhance this knowledge is to compare inhibition values obtained for one compound toward ortholog proteins from various species, which are highly conserved in sequence and differ only in few residues. In this study the inhibitory potencies of selected members of different non-steroidal inhibitor classes toward marmoset 17β-HSD1 were determined and the data were compared with the values obtained for the human enzyme. A species specific inhibition profile was observed in the class of the (hydroxyphenyl)naphthols. Using a combination of computational methods, including homology modelling, molecular docking, MD simulation, and binding energy calculation, a reasonable model of the three-dimensional structure of marmoset 17β-HSD1 was developed and inhibition data were rationalized on the structural basis. In marmoset 17β-HSD1, residues 190 to 196 form a small α-helix, which induces conformational changes compared to the human enzyme. The docking poses suggest these conformational changes as determinants for species specificity and energy decomposition analysis highlighted the outstanding role of Asn152 as interaction partner for inhibitor binding. In summary, this strategy of comparing the biological activities of inhibitors toward highly conserved ortholog proteins might be an alternative to laborious x-ray or site-directed mutagenesis experiments in certain cases. Additionally, it facilitates inhibitor design and optimization by offering new information on protein-ligand interactions.