Publications by authors named "Holger Stark"

390 Publications

Discovery of Potential, Dual-Active Histamine H Receptor Ligands with Combined Antioxidant Properties.

Molecules 2021 Apr 15;26(8). Epub 2021 Apr 15.

Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-699 Kraków, Poland.

In an attempt to find new dual acting histamine H receptor (HR) ligands, we designed a series of compounds, structurally based on previously described in our group, a highly active and selective human histamine H receptor (hHR) ligand KSK63. As a result, 15 obtained compounds show moderate hHR affinity, the best being the compound (hHR = 518 nM). Docking to the histamine HR homology model revealed two possible binding modes, with key interactions retained in both cases. In an attempt to find possible dual acting ligands, selected compounds were tested for antioxidant properties. Compound (hHR = 592 nM) showed the strongest antioxidant properties at the concentration of 10 mol/L. It significantly reduced the amount of free radicals presenting 50-60% of ascorbic acid activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, as well as showed antioxidative properties in the ferric reducing antioxidant power (FRAP) assay. Despite the yet unknown antioxidation mechanism and moderate hHR affinity, (QD13) constitutes a starting point for the search of potential dual acting HR ligands-promising tools for the treatment of neurological disorders associated with increased neuronal oxidative stress.
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http://dx.doi.org/10.3390/molecules26082300DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8071534PMC
April 2021

A pair of particles in inertial microfluidics: effect of shape, softness, and position.

Soft Matter 2021 Apr 19. Epub 2021 Apr 19.

Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.

Lab-on-a-chip devices based on inertial microfluidics have emerged as a promising technique to manipulate particles in a precise way. Inertial microfluidics exploits internal hydrodynamic forces and the mechanical structure of particles to achieve separation and focusing. The article focuses on the hydrodynamic interaction of two particles. This will help to develop an understanding of the dynamics of particle trains in inertial microfluidics, which are typical structures in multi-particle systems. We perform three-dimensional lattice Boltzmann simulations combined with the immersed boundary method to unravel the dynamics of various mono- and bi-dispersed pairs in inertial microfluidics. We study the influence of different starting positions for mono- and bi-dispersed pairs. We also change their deformability from relatively soft to rigid and choose spherical and biconcave particle shapes. The observed two-particle motions in the present work can be categorized into four types: stable pair, stable pair with damped oscillations, stable pair with bounded oscillations, and unstable pair. We show that stable pairs become unstable when increasing the particle stiffness. Furthermore, a pair with both capsules in the same channel half is more prone to become unstable than a pair with capsules in opposite channel halves.
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http://dx.doi.org/10.1039/d1sm00276gDOI Listing
April 2021

The histamine H3R and dopamine D2R/D3R antagonist ST-713 ameliorates autism-like behavioral features in BTBR T+tf/J mice by multiple actions.

Biomed Pharmacother 2021 Jun 24;138:111517. Epub 2021 Mar 24.

Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates; Zayed Center for Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates. Electronic address:

Several brain neurotransmitters, including histamine (HA), acetylcholine (ACh), and dopamine (DA) are suggested to be involved in several brain disorders including cognitive deficits, depression, schizophrenia, anxiety, and narcolepsy, all of which are comorbid with Autism spectrum disorder (ASD). Therefore, the ameliorative effects of the novel multiple-active compound ST-713 with high binding affinities at histamine H3 receptor (H3R), dopamine D2sR and D3R on ASD-like behaviors in male BTBR T+tf/J mice model were assessed. ST-713 (3-(2-chloro-10H-phenothiazin-10-yl)-N-methyl-N-(4-(3-(piperidin-1-yl)propoxy)benzyl)propan-1-amine; 2.5, 5, and 10 mg/kg, i.p.) ameliorated dose-dependently social deficits, and significantly alleviated the repetitive/compulsive behaviors of BTBR mice (all P < 0.05). Moreover, ST-713 modulated disturbed anxiety levels, but failed to obliterate increased hyperactivity of tested mice. Furthermore, ST-713 (5 mg/kg) attenuated the increased levels of hippocampal and cerebellar protein expressions of NF-κB p65, COX-2, and iNOS in BTBR mice (all P < 0.05). The ameliorative effects of ST-713 on social parameters were entirely reversed by co-administration of the H3R agonist (R)-α-methylhistamine or the anticholinergic drug scopolamine. The obtained results demonstrate the potential of multiple-active compounds for the therapeutic management of neuropsychiatric disorders, e.g. ASD.
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http://dx.doi.org/10.1016/j.biopha.2021.111517DOI Listing
June 2021

Demonstrating Ligandability of the LC3A and LC3B Adapter Interface.

J Med Chem 2021 Apr 26;64(7):3720-3746. Epub 2021 Mar 26.

Institute of Pharmaceutical Chemistry, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.

Autophagy is the common name for a number of lysosome-based degradation pathways of cytosolic cargos. The key components of autophagy are members of Atg8 family proteins involved in almost all steps of the process, from autophagosome formation to their selective fusion with lysosomes. In this study, we show that the homologous members of the human Atg8 family proteins, LC3A and LC3B, are druggable by a small molecule inhibitor novobiocin. Structure-activity relationship (SAR) studies of the 4-hydroxy coumarin core scaffold were performed, supported by a crystal structure of the LC3A dihydronovobiocin complex. The study reports the first nonpeptide inhibitors for these protein interaction targets and will lay the foundation for the development of more potent chemical probes for the Atg8 protein family which may also find applications for the development of autophagy-mediated degraders (AUTACs).
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http://dx.doi.org/10.1021/acs.jmedchem.0c01564DOI Listing
April 2021

The Multi-Targeting Ligand ST-2223 with Histamine H Receptor and Dopamine D/D Receptor Antagonist Properties Mitigates Autism-Like Repetitive Behaviors and Brain Oxidative Stress in Mice.

Int J Mol Sci 2021 Feb 16;22(4). Epub 2021 Feb 16.

Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates.

Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characterized by social and communicative impairments, as well as repetitive and restricted behaviors (RRBs). With the limited effectiveness of current pharmacotherapies in treating repetitive behaviors, the present study determined the effects of acute systemic treatment of the novel multi-targeting ligand ST-2223, with incorporated histamine H receptor (HR) and dopamine D/D receptor affinity properties, on ASD-related RRBs in a male Black and Tan BRachyury (BTBR) mouse model of ASD. ST-2223 (2.5, 5, and 10 mg/kg, i.p.) significantly mitigated the increase in marble burying and self-grooming, and improved reduced spontaneous alternation in BTBR mice (all < 0.05). Similarly, reference drugs memantine (MEM, 5 mg/kg, i.p.) and aripiprazole (ARP, 1 mg/kg, i.p.), reversed abnormally high levels of several RRBs in BTBR ( < 0.05). Moreover, ST-2223 palliated the disturbed anxiety levels observed in an open field test (all < 0.05), but did not restore the hyperactivity parameters, whereas MEM failed to restore mouse anxiety and hyperactivity. In addition, ST-2223 (5 mg/kg, i.p.) mitigated oxidative stress status by decreasing the elevated levels of malondialdehyde (MDA), and increasing the levels of decreased glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in different brain parts of treated BTBR mice (all < 0.05). These preliminary in vivo findings demonstrate the ameliorative effects of ST-2223 on RRBs in a mouse model of ASD, suggesting its pharmacological prospective to rescue core ASD-related behaviors. Further confirmatory investigations on its effects on various brain neurotransmitters, e.g., dopamine and histamine, in different brain regions are still warranted to corroborate and expand these initial data.
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http://dx.doi.org/10.3390/ijms22041947DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7920280PMC
February 2021

Synthesis, in silico, and in vitro studies of novel dopamine D and D receptor ligands.

Arch Pharm (Weinheim) 2021 Feb 22:e2000486. Epub 2021 Feb 22.

Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Universitaetsstr. 1, Duesseldorf, NRW, Germany.

Dopamine is an important neurotransmitter in the human brain and its altered concentrations can lead to various neurological diseases. We studied the binding of novel compounds at the dopamine D (D R) and D (D R) receptor subtypes, which belong to the D -like receptor family. The synthesis, in silico, and in vitro characterization of 10 dopamine receptor ligands were performed. Novel ligands were docked into the D R and D R crystal structures to examine the precise binding mode. A quantum mechanics/molecular mechanics study was performed to gain insights into the nature of the intermolecular interactions between the newly introduced pentafluorosulfanyl (SF ) moiety and D R and D R. A radioligand displacement assay determined that all of the ligands showed moderate-to-low nanomolar affinities at D R and D R, with a slight preference for D R, which was confirmed in the in silico studies. N-{4-[4-(2-Methoxyphenyl)piperazin-1-yl]butyl}-4-(pentafluoro-λ6-sulfanyl)benzamide (7i) showed the highest D R affinity and selectivity (pK values of 7.14 [D R] and 8.42 [D R]).
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http://dx.doi.org/10.1002/ardp.202000486DOI Listing
February 2021

Steering droplets on substrates using moving steps in wettability.

Soft Matter 2021 Mar;17(9):2454-2467

Technische Universität Berlin, Institut für Theoretische Physik, Straße des 17. Juni 135, 10623 Berlin, Germany.

Droplets move on substrates with a spatio-temporal wettability pattern as generated, for example, on light-switchable surfaces. To study such cases, we implement the boundary-element method to solve the governing Stokes equations for the fluid flow field inside and on the surface of a droplet and supplement it by the Cox-Voinov law for the dynamics of the contact line. Our approach reproduces the relaxation of an axisymmetric droplet in experiments, which we initiate by instantaneously switching the uniform wettability of a substrate quantified by the equilibrium contact angle. In a step profile of wettability the droplet moves towards higher wettability. Using a feedback loop to keep the distance or offset between step and droplet center constant, induces a constant velocity with which the droplet surfs on the wettability step. We analyze the velocity in terms of droplet offset and step width for typical wetting parameters. Moving instead the wettability step with constant speed, we determine the maximally possible droplet velocities under various conditions. The observed droplet speeds agree with the values from the feedback study for the same positive droplet offset.
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http://dx.doi.org/10.1039/d0sm02082fDOI Listing
March 2021

Novel compounds with dual S1P receptor agonist and histamine H receptor antagonist activities act protective in a mouse model of multiple sclerosis.

Neuropharmacology 2021 03 16;186:108464. Epub 2021 Jan 16.

Institute of Pharmacology, University of Bern, Inselspital INO-F, CH-3010, Bern, Switzerland. Electronic address:

The sphingosine 1-phosphate (S1P) receptor 1 (S1P) has emerged as a therapeutic target for the treatment of multiple sclerosis (MS). Fingolimod (FTY720) is the first functional antagonist of S1P that has been approved for oral treatment of MS. Previously, we have developed novel butterfly derivatives of FTY720 that acted similar to FTY720 in reducing disease symptoms in a mouse model of experimental autoimmune encephalomyelitis (EAE). In this study, we have synthesized a piperidine derivative of the oxazolo-oxazole compounds, denoted ST-1505, and its ring-opened analogue ST-1478, and characterised their in-vitro and in-vivo functions. Notably, the 3-piperidinopropyloxy moiety resembles a structural motif of pitolisant, a drug with histamine HR antagonistic/inverse agonist activity approved for the treatment of narcolepsy. Both novel compounds exerted HR affinities, and in addition, ST-1505 was characterised as a dual S1P agonist, whereas ST-1478 was a dual S1P agonist. Both multitargeting compounds were also active in mice and reduced the lymphocyte numbers as well as diminished disease symptoms in the mouse model of MS. The effect of ST-1478 was dependent on SK-2 activity suggesting that it is a prodrug like FTY720, but with a more selective S1P receptor activation profile, whereas ST-1505 is a fully active drug even in the absence of SK-2. In summary, these data suggest that the well soluble piperidine derivatives ST-1505 and ST-1478 hold promise as novel drugs for the treatment of MS and other autoimmune or inflammatory diseases, and by their HR antagonist potency, they might additionally improve cognitive impairment during disease.
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http://dx.doi.org/10.1016/j.neuropharm.2021.108464DOI Listing
March 2021

Multi-particle collision dynamics with a non-ideal equation of state. I.

J Chem Phys 2021 Jan;154(2):024105

Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany.

The method of multi-particle collision dynamics (MPCD) and its different implementations are commonly used in the field of soft matter physics to simulate fluid flow at the micron scale. Typically, the coarse-grained fluid particles are described by the equation of state of an ideal gas, and the fluid is rather compressible. This is in contrast to conventional fluids, which are incompressible for velocities much below the speed of sound, and can cause inhomogeneities in density. We propose an algorithm for MPCD with a modified collision rule that results in a non-ideal equation of state and a significantly decreased compressibility. It allows simulations at less computational costs compared to conventional MPCD algorithms. We derive analytic expressions for the equation of state and the corresponding compressibility as well as shear viscosity. They show overall very good agreement with simulations, where we determine the pressure by simulating a quiet bulk fluid and the shear viscosity by simulating a linear shear flow and a Poiseuille flow.
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http://dx.doi.org/10.1063/5.0037934DOI Listing
January 2021

Structural modifications in the distal, regulatory region of histamine H receptor antagonists leading to the identification of a potent anti-obesity agent.

Eur J Med Chem 2021 Mar 24;213:113041. Epub 2020 Nov 24.

Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Kraków, 30-688, Poland. Electronic address:

A series of 4-pyridylpiperazine derivatives with varying regulatory region substituents proved to be potent histamine H receptor (HR) ligands in the nanomolar concentration range. The most influential modification that affected the affinity toward the HR appeared by introducing electron-withdrawing moieties into the distal aromatic ring. In order to finally discuss the influence of the characteristic 4-pyridylpiperazine moiety on HR affinity, two Ciproxifan analogues 2 and 3 with a slight modification in their basic part were obtained. The replacement of piperazine in 3 with piperidine in compound 2, led to slightly reduced affinity towards the HR (K = 3.17 and 7.70 nM, respectively). In fact, 3 showed the highest antagonistic properties among all compounds in this series, hence affirming our previous assumptions, that the 4-pyridylpiperazine moiety is the key element for suitable interaction with the human histamine H receptor. While its structural replacement to piperidine is also tolerated for HR binding, the heteroaromatic 4-pyridyl moiety seems to be essential for proper ligand-receptor interaction. The putative protein-ligand interactions responsible for their high affinity were demonstrated using molecular modeling techniques. Furthermore, selectivity, intrinsic activity at the HR, as well as drug-like properties of ligands were evaluated using in vitro methods. Moreover, pharmacological in vivo test results of compound 9 (structural analogue of Abbott's A-331440) clearly indicate that it may affect the amount of calories consumed, thus act as an anorectic compound.
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http://dx.doi.org/10.1016/j.ejmech.2020.113041DOI Listing
March 2021

Mechanism of protein-guided folding of the active site U2/U6 RNA during spliceosome activation.

Science 2020 12 26;370(6523). Epub 2020 Nov 26.

Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.

Spliceosome activation involves extensive protein and RNA rearrangements that lead to formation of a catalytically active U2/U6 RNA structure. At present, little is known about the assembly pathway of the latter and the mechanism whereby proteins aid its proper folding. Here, we report the cryo-electron microscopy structures of two human, activated spliceosome precursors (that is, pre-B complexes) at core resolutions of 3.9 and 4.2 angstroms. These structures elucidate the order of the numerous protein exchanges that occur during activation, the mutually exclusive interactions that ensure the correct order of ribonucleoprotein rearrangements needed to form the U2/U6 catalytic RNA, and the stepwise folding pathway of the latter. Structural comparisons with mature B complexes reveal the molecular mechanism whereby a conformational change in the scaffold protein PRP8 facilitates final three-dimensional folding of the U2/U6 catalytic RNA.
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http://dx.doi.org/10.1126/science.abc3753DOI Listing
December 2020

Atomic-resolution protein structure determination by cryo-EM.

Nature 2020 11 21;587(7832):157-161. Epub 2020 Oct 21.

Department of Structural Dynamics, MPI for Biophysical Chemistry, Göttingen, Germany.

Single-particle electron cryo-microscopy (cryo-EM) is a powerful method for solving the three-dimensional structures of biological macromolecules. The technological development of transmission electron microscopes, detectors and automated procedures in combination with user-friendly image processing software and ever-increasing computational power have made cryo-EM a successful and expanding technology over the past decade. At resolutions better than 4 Å, atomic model building starts to become possible, but the direct visualization of true atomic positions in protein structure determination requires much higher (better than 1.5 Å) resolution, which so far has not been attained by cryo-EM. The direct visualization of atom positions is essential for understanding the mechanisms of protein-catalysed chemical reactions, and for studying how drugs bind to and interfere with the function of proteins. Here we report a 1.25 Å-resolution structure of apoferritin obtained by cryo-EM with a newly developed electron microscope that provides, to our knowledge, unprecedented structural detail. Our apoferritin structure has almost twice the 3D information content of the current world record reconstruction (at 1.54 Å resolution). We can visualize individual atoms in a protein, see density for hydrogen atoms and image single-atom chemical modifications. Beyond the nominal improvement in resolution, we also achieve a substantial improvement in the quality of the cryo-EM density map, which is highly relevant for using cryo-EM in structure-based drug design.
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http://dx.doi.org/10.1038/s41586-020-2833-4DOI Listing
November 2020

Eosinophils adhesion assay as a tool for phenotypic drug screening - The pharmacology of 1,3,5 - Triazine and 1H-indole like derivatives against the human histamine H receptor.

Eur J Pharmacol 2021 Jan 2;890:173611. Epub 2020 Oct 2.

Jagiellonian University Medical College, Faculty of Pharmacy, Department of Technology and Biotechnology of Drugs, Medyczna 9, 30-688, Kraków, Poland. Electronic address:

Histamine is a pleiotropic biogenic amine, having affinity towards four distinct histamine receptors. The existing pharmacological studies suggest the usefulness of histamine H receptor ligands in the treatment of many inflammatory and immunomodulatory diseases, including allergic rhinitis, asthma, atopic dermatitis, colitis or pruritus. Up to date, several potent histamine H receptor ligands were developed, none of which was registered as a drug yet. In this study, a series of potent indole-like and triazine derivatives were tested, in radioligand displacement and functional assays at histamine H receptor, as well as in human eosinophils adhesion assay to endothelium. For selected compounds permeability, cytotoxicity, metabolic and in vivo studies were conducted. Adhesion assay differentiated the activity of different groups of compounds with a known affinity towards the histamine H receptor. Most of the tested compounds downregulated the number of adherent cells. However, adhesion assay revealed additional properties of tested compounds that had not been detected in radioligand displacement and aequorin-based functional assays. Furthermore, for some tested compounds, these abnormal effects were confirmed during the in vivo studies. In conclusion, eosinophils adhesion assay uncovered pharmacological activity of histamine H receptor ligands that has been later confirmed in vivo, underscoring the value of well-suited cell-based phenotypic screening approach in drug discovery.
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http://dx.doi.org/10.1016/j.ejphar.2020.173611DOI Listing
January 2021

Structural Insights into the Roles of Metazoan-Specific Splicing Factors in the Human Step 1 Spliceosome.

Mol Cell 2020 10;80(1):127-139.e6

Cellular Biochemistry, MPI for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany. Electronic address:

Human spliceosomes contain numerous proteins absent in yeast, whose functions remain largely unknown. Here we report a 3D cryo-EM structure of the human spliceosomal C complex at 3.4 Å core resolution and 4.5-5.7 Å at its periphery, and aided by protein crosslinking we determine its molecular architecture. Our structure provides additional insights into the spliceosome's architecture between the catalytic steps of splicing, and how proteins aid formation of the spliceosome's catalytically active RNP (ribonucleoprotein) conformation. It reveals the spatial organization of the metazoan-specific proteins PPWD1, WDR70, FRG1, and CIR1 in human C complexes, indicating they stabilize functionally important protein domains and RNA structures rearranged/repositioned during the B to C transition. Structural comparisons with human B, C, and P complexes reveal an intricate cascade of RNP rearrangements during splicing catalysis, with intermediate RNP conformations not found in yeast, and additionally elucidate the structural basis for the sequential recruitment of metazoan-specific spliceosomal proteins.
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http://dx.doi.org/10.1016/j.molcel.2020.09.012DOI Listing
October 2020

Active open-loop control of elastic turbulence.

Sci Rep 2020 Sep 24;10(1):15704. Epub 2020 Sep 24.

Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstrasse 36, 10623, Berlin, Germany.

We demonstrate through numerical solutions of the Oldroyd-B model in a two-dimensional Taylor-Couette geometry that the onset of elastic turbulence in a viscoelastic fluid can be controlled by imposed shear-rate modulations, one form of active open-loop control. Slow modulations display rich and complex behavior where elastic turbulence is still present, while it vanishes for fast modulations and a laminar response with the Taylor-Couette base flow is recovered. We find that the transition from the laminar to the turbulent state is supercritical and occurs at a critical Deborah number. In the state diagram of both control parameters, Weissenberg versus Deborah number, we identify the region of elastic turbulence. We also quantify the transition by the flow resistance, for which we derive an analytic expression in the laminar regime within the linear Oldroyd-B model. Finally, we provide an approximation for the transition line in the state diagram introducing an effective critical Weissenberg number in comparison to constant shear. Deviations from the numerical result indicate that the physics behind the observed laminar-to-turbulent transition is more complex under time-modulated shear flow.
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http://dx.doi.org/10.1038/s41598-020-72402-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7519150PMC
September 2020

Morpholino Analogues of Fingolimod as Novel and Selective S1P Ligands with In Vivo Efficacy in a Mouse Model of Experimental Antigen-Induced Encephalomyelitis.

Int J Mol Sci 2020 Sep 4;21(18). Epub 2020 Sep 4.

Institute of Pharmacology, University of Bern, Inselspital INO-F, CH-3010 Bern, Switzerland.

Multiple sclerosis (MS) is a chronic, inflammatory, autoimmune disease of the central nervous system (CNS) which is associated with lower life expectancy and disability. The experimental antigen-induced encephalomyelitis (EAE) in mice is a useful animal model of MS, which allows exploring the etiopathogenetic mechanisms and testing novel potential therapeutic drugs. A new therapeutic paradigm for the treatment of MS was introduced in 2010 through the sphingosine 1-phosphate (S1P) analogue fingolimod (FTY720, Gilenya), which acts as a functional S1P antagonist on T lymphocytes to deplete these cells from the blood. In this study, we synthesized two novel structures, ST-1893 and ST-1894, which are derived from fingolimod and chemically feature a morpholine ring in the polar head group. These compounds showed a selective S1P activation profile and a sustained S1P internalization in cultures of S1P-overexpressing Chinese hamster ovary (CHO)-K1 cells, consistent with a functional antagonism. In vivo, both compounds induced a profound lymphopenia in mice. Finally, these substances showed efficacy in the EAE model, where they reduced clinical symptoms of the disease, and, on the molecular level, they reduced the T-cell infiltration and several inflammatory mediators in the brain and spinal cord. In summary, these data suggest that S1P-selective compounds may have an advantage over fingolimod and siponimod, not only in MS but also in other autoimmune diseases.
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http://dx.doi.org/10.3390/ijms21186463DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7555234PMC
September 2020

Simultaneous Blockade of Histamine H Receptors and Inhibition of Acetylcholine Esterase Alleviate Autistic-Like Behaviors in BTBR T+ tf/J Mouse Model of Autism.

Biomolecules 2020 08 28;10(9). Epub 2020 Aug 28.

Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, UAE.

Autism spectrum disorder (ASD) is a heterogenous neurodevelopmental disorder defined by persistent deficits in social interaction and the presence of patterns of repetitive and restricted behaviors. The central neurotransmitters histamine (HA) and acetylcholine (ACh) play pleiotropic roles in physiological brain functions that include the maintenance of wakefulness, depression, schizophrenia, epilepsy, anxiety and narcolepsy, all of which are found to be comorbid with ASD. Therefore, the palliative effects of subchronic systemic treatment using the multiple-active test compound E100 with high HR antagonist affinity and AChE inhibitory effect on ASD-like behaviors in male BTBR T+tf/J (BTBR) mice as an idiopathic ASD model were assessed. E100 (5, 10 and 15 mg/kg, i.p.) dose-dependently palliated social deficits of BTBR mice and significantly alleviated the repetitive/compulsive behaviors of tested animals. Moreover, E100 modulated disturbed anxiety levels, but failed to modulate hyperactivity parameters, whereas the reference AChE inhibitor donepezil (DOZ, one milligram per kilogram) significantly obliterated the increased hyperactivity measures of tested mice. Furthermore, E100 mitigated the increased levels of AChE activity in BTBR mice with observed effects comparable to that of DOZ and significantly reduced the number of activated microglial cells compared to the saline-treated BTBR mice. In addition, the E100-provided effects on ASD-like parameters, AChE activity, and activated microglial cells were entirely reversed by co-administration of the HR agonist ()-α-methylhistamine (RAM). These initial overall results observed in an idiopathic ASD mice model show that E100 (5 mg/kg) alleviated the assessed behavioral deficits and demonstrate that simultaneous targeting of brain histaminergic and cholinergic neurotransmissions is crucial for palliation of ASD-like features, albeit further in vivo assessments on its effects on brain levels of ACh as well as HA are still needed.
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http://dx.doi.org/10.3390/biom10091251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7563744PMC
August 2020

N-Substituted piperazine derivatives as potential multitarget agents acting on histamine H receptor and cancer resistance proteins.

Bioorg Med Chem Lett 2020 11 29;30(22):127522. Epub 2020 Aug 29.

Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Kraków 30-688, Poland.

Taking into account that multidrug resistance (MDR) is the main cause for chemotherapeutic failure in cancer treatment, the ability of novel histamine H receptor ligands to reverse the cancer MDR was evaluated, using the ABCB1 efflux pump inhibition assay in mouse MDR T-lymphoma cells. The most active compounds displayed significant cytotoxic and antiproliferative effects as well as a very potent MDR efflux pump inhibitory action, 3-5-fold stronger than that of reference inhibitor verapamil. Although these compounds possess weak antagonistic properties against histamine H receptors, they are valuable pharmacological tools in the search for novel anticancer molecules. Furthermore, for the most active compounds, an insight into mechanisms of action using either, the luminescent Pgp-Glo™ Assay in vitro or docking studies to human Pgp, was performed.
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http://dx.doi.org/10.1016/j.bmcl.2020.127522DOI Listing
November 2020

Epigenetics meets GPCR: inhibition of histone H3 methyltransferase (G9a) and histamine H receptor for Prader-Willi Syndrome.

Sci Rep 2020 08 11;10(1):13558. Epub 2020 Aug 11.

Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225, Duesseldorf, Germany.

The role of epigenetic regulation is in large parts connected to cancer, but additionally, its therapeutic claim in neurological disorders has emerged. Inhibition of histone H3 lysine N-methyltransferase, especially G9a, has been recently shown to restore candidate genes from silenced parental chromosomes in the imprinting disorder Prader-Willi syndrome (PWS). In addition to this epigenetic approach, pitolisant as G-protein coupled histamine H receptor (HR) antagonist has demonstrated promising therapeutic effects for Prader-Willi syndrome. To combine these pioneering principles of drug action, we aimed to identify compounds that combine both activities, guided by the pharmacophore blueprint for both targets. However, pitolisant as selective HR inverse agonist with FDA and EMA-approval did not show the required inhibition at G9a. Pharmacological characterization of the prominent G9a inhibitor A-366, that is as well an inhibitor of the epigenetic reader protein Spindlin1, revealed its high affinity at HR while showing subtype selectivity among subsets of the histaminergic and dopaminergic receptor families. This work moves prominent G9a ligands forward as pharmacological tools to prove for a potentially combined, symptomatic and causal, therapy in PWS by bridging the gap between drug development for G-protein coupled receptors and G9a as an epigenetic effector in a multi-targeting approach.
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http://dx.doi.org/10.1038/s41598-020-70523-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7419559PMC
August 2020

Particle pairs and trains in inertial microfluidics.

Eur Phys J E Soft Matter 2020 Aug 4;43(8):50. Epub 2020 Aug 4.

Technische Universität Berlin, Institut für Theoretische Physik, Straße des 17. Juni 135, 10623, Berlin, Germany.

Staggered and linear multi-particle trains constitute characteristic structures in inertial microfluidics. Using lattice-Boltzmann simulations, we investigate their properties and stability, when flowing through microfluidic channels. We confirm the stability of cross-streamline pairs by showing how they contract or expand to their equilibrium axial distance. In contrast, same-streamline pairs quickly expand to a characteristic separation but even at long times slowly drift apart. We reproduce the distribution of particle distances with its characteristic peak as measured in experiments. Staggered multi-particle trains initialized with an axial particle spacing larger than the equilibrium distance contract non-uniformly due to collective drag reduction. Linear particle trains, similar to pairs, rapidly expand toward a value about twice the equilibrium distance of staggered trains and then very slowly drift apart non-uniformly. Again, we reproduce the statistics of particle distances and the characteristic peak observed in experiments. Finally, we thoroughly analyze the damped displacement pulse traveling as a microfluidic phonon through a staggered train and show how a defect strongly damps its propagation.
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http://dx.doi.org/10.1140/epje/i2020-11975-6DOI Listing
August 2020

Squirmer rods as elongated microswimmers: flow fields and confinement.

Soft Matter 2020 Jul 25;16(27):6400-6412. Epub 2020 Jun 25.

Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany.

Microswimmers or active elements, such as bacteria and active filaments, have an elongated shape, which determines their individual and collective dynamics. There is still a need to identify what role long-range hydrodynamic interactions play in their fascinating dynamic structure formation. We construct rods of different aspect ratios using several spherical squirmer model swimmers. With the help of the mesoscale simulation method of multi-particle collision dynamics we analyze the flow fields of these squirmer rods both in a bulk fluid and in Hele-Shaw geometries of different slab widths. Based on the hydrodynamic multipole expansion either for bulk or confinement between two parallel plates, we categorize the different multipole contributions of neutral as well as pusher-type squirmer rods. We demonstrate how confinement alters the radial decay of the flow fields for a given force or source multipole moment compared to the bulk fluid.
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http://dx.doi.org/10.1039/d0sm00616eDOI Listing
July 2020

The chemical probe - scopes, limitations and challenges.

Authors:
Holger Stark

Expert Opin Drug Discov 2020 12 19;15(12):1365-1367. Epub 2020 Jun 19.

Heinrich Heine University Düsseldorf, Institut fuer Pharmazeutische und Medizinische Chemie , Duesseldorf, Germany.

Drug design needs high-quality chemical probes for target validation, but the demands on chemical probes are largely different than those on drugs. Whereas therapeutic value and safety are main criteria for a drug evaluation, the chemical probe is influencing a biological target in a well-characterized way. Affinity, efficacy, selectivity and versatility in different read-outs are main criteria for chemical probes to test biochemical hypothesis and verify targets for new therapeutic approaches.
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http://dx.doi.org/10.1080/17460441.2020.1781086DOI Listing
December 2020

Optimal Control of Colloidal Trajectories in Inertial Microfluidics Using the Saffman Effect.

Micromachines (Basel) 2020 Jun 15;11(6). Epub 2020 Jun 15.

Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin, Germany.

In inertial microfluidics colloidal particles in a Poiseuille flow experience the Segré-Silberberg lift force, which drives them to specific positions in the channel cross section. An external force applied along the microchannel induces a cross-streamline migration to a new equilibrium position because of the Saffman effect. We apply optimal control theory to design the time protocol of the axial control force in order to steer a single particle as precisely as possible from a channel inlet to an outlet at a chosen target position. We discuss the influence of particle radius and channel length and show that optimal steering is cheaper than using a constant control force. Using a single optimized control-force protocol, we demonstrate that even a pulse of particles spread along the channel axis can be steered to a target and that particles of different radii can be separarted most efficiently.
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http://dx.doi.org/10.3390/mi11060592DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7345581PMC
June 2020

The Dual-Active Histamine H Receptor Antagonist and Acetylcholine Esterase Inhibitor E100 Alleviates Autistic-Like Behaviors and Oxidative Stress in Valproic Acid Induced Autism in Mice.

Int J Mol Sci 2020 Jun 3;21(11). Epub 2020 Jun 3.

Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, UAE.

The histamine H3 receptor (H3R) functions as auto- and hetero-receptors, regulating the release of brain histamine (HA) and acetylcholine (ACh), respectively. The enzyme acetylcholine esterase (AChE) is involved in the metabolism of brain ACh. Both brain HA and ACh are implicated in several cognitive disorders like Alzheimer's disease, schizophrenia, anxiety, and narcolepsy, all of which are comorbid with autistic spectrum disorder (ASD). Therefore, the novel dual-active ligand E100 with high H3R antagonist affinity (hH3R: = 203 nM) and balanced AChE inhibitory effect (AChE: IC = 2 µM and BuChE: IC = 2 µM) was investigated on autistic-like sociability, repetitive/compulsive behaviour, anxiety, and oxidative stress in male C57BL/6 mice model of ASD induced by prenatal exposure to valproic acid (VPA, 500 mg/kg, intraperitoneal (i.p.)). Subchronic systemic administration with E100 (5, 10, and 15 mg/kg, i.p.) significantly and dose-dependently attenuated sociability deficits of autistic (VPA) mice in three-chamber behaviour (TCB) test (all < 0.05). Moreover, E100 significantly improved repetitive and compulsive behaviors by reducing the increased percentage of marbles buried in marble-burying behaviour (MBB) (all < 0.05). Furthermore, pre-treatment with E100 (10 and 15 mg/kg, i.p.) corrected decreased anxiety levels ( < 0.05), however, failed to restore hyperactivity observed in elevated plus maze (EPM) test. In addition, E100 (10 mg/kg, i.p.) mitigated oxidative stress status by increasing the levels of decreased glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT), and decreasing the elevated levels of malondialdehyde (MDA) in the cerebellar tissues (all < 0.05). Additionally, E100 (10 mg/kg, i.p.) significantly reduced the elevated levels of AChE activity in VPA mice ( < 0.05). These results demonstrate the promising effects of E100 on in-vivo VPA-induced ASD-like features in mice, and provide evidence that a potent dual-active H3R antagonist and AChE inhibitor (AChEI) is a potential drug candidate for future therapeutic management of autistic-like behaviours.
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http://dx.doi.org/10.3390/ijms21113996DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7312782PMC
June 2020

Molecular architecture of the human 17S U2 snRNP.

Nature 2020 07 3;583(7815):310-313. Epub 2020 Jun 3.

Department of Structural Dynamics, MPI for Biophysical Chemistry, Göttingen, Germany.

The U2 small nuclear ribonucleoprotein (snRNP) has an essential role in the selection of the precursor mRNA branch-site adenosine, the nucleophile for the first step of splicing. Stable addition of U2 during early spliceosome formation requires the DEAD-box ATPase PRP5. Yeast U2 small nuclear RNA (snRNA) nucleotides that form base pairs with the branch site are initially sequestered in a branchpoint-interacting stem-loop (BSL), but whether the human U2 snRNA folds in a similar manner is unknown. The U2 SF3B1 protein, a common mutational target in haematopoietic cancers, contains a HEAT domain (SF3B1) with an open conformation in isolated SF3b, but a closed conformation in spliceosomes, which is required for stable interaction between U2 and the branch site. Here we report a 3D cryo-electron microscopy structure of the human 17S U2 snRNP at a core resolution of 4.1 Å and combine it with protein crosslinking data to determine the molecular architecture of this snRNP. Our structure reveals that SF3B1 interacts with PRP5 and TAT-SF1, and maintains its open conformation in U2 snRNP, and that U2 snRNA forms a BSL that is sandwiched between PRP5, TAT-SF1 and SF3B1. Thus, substantial remodelling of the BSL and displacement of BSL-interacting proteins must occur to allow formation of the U2-branch-site helix. Our studies provide a structural explanation of why TAT-SF1 must be displaced before the stable addition of U2 to the spliceosome, and identify RNP rearrangements facilitated by PRP5 that are required for stable interaction between U2 and the branch site.
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http://dx.doi.org/10.1038/s41586-020-2344-3DOI Listing
July 2020

Emergent collective dynamics of bottom-heavy squirmers under gravity.

Eur Phys J E Soft Matter 2020 May 25;43(5):26. Epub 2020 May 25.

Technische Universität Berlin, Institut für Theoretische Physik, Hardenbergstr. 36, D-10623, Berlin, Germany.

We present the results of hydrodynamic simulations using the method of multi-particle collision dynamics for a system of squirmer microswimmers moving under the influence of gravity at low Reynolds numbers. In addition, the squirmers are bottom-heavy so that they experience a torque which aligns them along the vertical. The squirmers interact hydrodynamically by the flow fields of a stokeslet and rotlet, which are initiated by the acting gravitational force and torque, respectively, and by their own flow fields. By varying the ratio of swimming to bulk sedimentation velocity and the torque, we determine state diagrams for the emergent collective dynamics of neutral squirmers as well as strong pushers and pullers. For low swimming velocity and torque we observe conventional sedimentation, while the sedimentation profile becomes inverted when their values are increased. For neutral squirmers we discover convective rolls of circulating squirmers between both sedimentation states, which sit at the bottom of the system and are fed by plumes made of collectively sinking squirmers. At larger torques porous clusters occur that spawn single squirmers. The two latter states can also occur transiently starting from a uniform squirmer distribution and then disappear in the long-time limit. For strong pushers and pullers only weak plume formation is observed.
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http://dx.doi.org/10.1140/epje/i2020-11949-8DOI Listing
May 2020

Dual Target Ligands with 4-Butylphenoxy Scaffold as Histamine H Receptor Antagonists and Monoamine Oxidase B Inhibitors.

Int J Mol Sci 2020 May 12;21(10). Epub 2020 May 12.

Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, 9 Medyczna Str, 30-688 Kraków, Poland.

Dual target ligands are a promising concept for the treatment of Parkinson's disease (PD). A combination of monoamine oxidase B (MAO B) inhibition with histamine H receptor (HR) antagonism could have positive effects on dopamine regulation. Thus, a series of twenty-seven 4--butylphenoxyalkoxyamines were designed as potential dual-target ligands for PD based on the structure of 1-(3-(4--butylphenoxy)propyl)piperidine (). Probed modifications included the introduction of different cyclic amines and elongation of the alkyl chain. Synthesized compounds were investigated for human HR (hHR) affinity and human MAO B (hMAO B) inhibitory activity. Most compounds showed good hHR affinities with K values below 400 nM, and some of them showed potent inhibitory activity for hMAO B with IC values below 50 nM. However, the most balanced activity against both biological targets showed (hHR: K = 38 nM and hMAO B: IC = 48 nM). Thus, was chosen for further studies, revealing the nontoxic nature of in HEK293 and neuroblastoma SH-SY5Ycells. However, no neuroprotective effect was observed for in hydrogen peroxide-treated neuroblastoma SH-SY5Y cells. Furthermore, in vivo studies showed antiparkinsonian activity of in haloperidol-induced catalepsy (Cross Leg Position Test) at a dose of 50 mg/kg body weight.
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http://dx.doi.org/10.3390/ijms21103411DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7279487PMC
May 2020

Discovery of a Regulatory Subunit of the Yeast Fatty Acid Synthase.

Cell 2020 03 10;180(6):1130-1143.e20. Epub 2020 Mar 10.

Department of Structural Dynamics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany. Electronic address:

Fatty acid synthases (FASs) are central to metabolism but are also of biotechnological interest for the production of fine chemicals and biofuels from renewable resources. During fatty acid synthesis, the growing fatty acid chain is thought to be shuttled by the dynamic acyl carrier protein domain to several enzyme active sites. Here, we report the discovery of a γ subunit of the 2.6 megadalton α-βS. cerevisiae FAS, which is shown by high-resolution structures to stabilize a rotated FAS conformation and rearrange ACP domains from equatorial to axial positions. The γ subunit spans the length of the FAS inner cavity, impeding reductase activities of FAS, regulating NADPH turnover by kinetic hysteresis at the ketoreductase, and suppressing off-pathway reactions at the enoylreductase. The γ subunit delineates the functional compartment within FAS. As a scaffold, it may be exploited to incorporate natural and designed enzymatic activities that are not present in natural FAS.
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http://dx.doi.org/10.1016/j.cell.2020.02.034DOI Listing
March 2020

Isoquinoline alkaloids from the roots of Zanthoxylum rigidum as multi-target inhibitors of cholinesterase, monoamine oxidase A and Aβ aggregation.

Bioorg Chem 2020 05 4;98:103722. Epub 2020 Mar 4.

Universidad Nacional de Colombia, Sede Bogotá, Facultad de Ciencias, Departamento de Química, Grupo de Investigación en Productos Naturales Vegetales Bioactivos, Cr 30 N°45-03, 111321 Bogotá, Colombia.

Multifactorial neurodegenerative disorders such as Alzheimer's disease (AD) are considered a growing public health problem due the rising incidence and low effectiveness of current treatments [6]. Since pharmacotherapy based on a single target has been insufficient for drug development in complex diseases, the emerging multi-target approach is a promising strategy for the search of new anti-AD drug candidates. Herein described natural isoquinoline alkaloids were investigated for multi-target activity on key mechanisms associated with the AD's pathogenesis, i.e. cholinergic depletion, beta amyloid (Aβ) aggregation and oxidative stress. Alkaloid isolation from root extract of Zanthoxylum rigidum was carried out using multi-step chromatography and TLC-bioautography against acetylcholinesterase (AChE) giving eight purified isoquinoline alkaloids. Isolated compounds were tested for inhibitory activity against cholinesterase (AChE and BChE), monoamine oxidase (MAO-A and B) and Aβ aggregation. Our study revealed two benzophenanthridine alkaloids, nitidine (5) and avicine (7), as the most potent multi-target candidates. Both showed dual cholinesterase inhibition, being more active against AChE over BChE, with IC values in sub-micromolar range in AChE. Kinetic analysis with cholinesterase showed, that both compounds are reversible-mixed inhibitors, where avicine (7) presented highest potency with K values of 0.063 µM (EeAChE), 0.511 µM (HrAChE) and 0.123 µM (EqBChE). In addition, these alkaloids presented moderate Aβ anti-aggregation activity and MAO-A inhibition with IC values between 0.5 and 2 µM. Our findings suggest that avicine (7) is a promising natural compound and multifunctional candidate representing a suitable starting point for the development of new therapeutic agents for Alzheimer's disease.
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http://dx.doi.org/10.1016/j.bioorg.2020.103722DOI Listing
May 2020