Rolf W Hartmann

Universität des Saarlandes, Saarbrücken, Saarland, Germany

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Publications (375)1103.8 Total impact

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    ABSTRACT: Infections with Pseudomonas aeruginosa have become a concerning threat in hospital-acquired infections and for cystic fibrosis patients. The major problem leading to high mortality lies in the appearance of drug-resistant strains. Therefore, a vast number of approaches to develop novel anti-infectives is currently pursued. These diverse strategies span from killing (new antibiotics) to disarming (anti-virulence) the pathogen. Particular emphasis lies on the development of compounds that inhibit biofilms formed in chronic infections to restore susceptibility towards antibiotics. Numerous promising results are summarized in this perspective. Antibiotics with a novel mode of action will be needed to avoid cross resistance against currently used therapeutic agents. Importantly, anti-virulence drugs are expected to yield a significantly reduced rate of resistance development. Most developments are still far from the application. It can however be expected that combination therapies, also containing anti-virulence agents, will pave the way towards novel treatment options against P. aeruginosa.
    No preview · Article · Jan 2016 · Journal of Medicinal Chemistry
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    ABSTRACT: Twelve derivatives of the general formula 3-substituted-6-chloroindoles were synthesized and tested for their growth inhibitory effects versus p53<sup>+/+</sup> colorectal cancer HCT116 and its p53 knockout isogenic cells; colorectal cancer cell p53<sup>-/-</sup> SW480; the lung cancer cell line p53<sup>-/-</sup> H1299; mouse embryonic fibroblasts (MEF) p53<sup>+/+</sup> and its p53 knockout isogenic cells. The compounds were also evaluated for their ability to induce p53 nuclear translocation and binding to murine double minute 2 (MDM2) and murine double minute 4 (MDM4). Of these, compound 5a was the most active in inhibiting the growth of cells, with selectivity towards the p53<sup>+/+</sup> cell lines, and it showed stronger binding to MDM4 rather than MDM2. The activity profile of compound 5a is strongly similar to that of Nutlin-3.
    Full-text · Article · Jan 2016 · CHEMICAL & PHARMACEUTICAL BULLETIN
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    Andreas Thomann · Volker Huch · Rolf W. Hartmann
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    ABSTRACT: The title compound, C 6 H 6 N 6 S, crystallized with two independent molecules ( A and B ) in the asymmetric unit. The conformation of the two molecules differs slightly. While the tetrazole ring is inclined to the pyrimidene ring by 5.48 (7) and 4.24 (7)° in molecules A and B , respectively, the N—C—S—C torsion angles of the thiomethyl groups differ by ca 180°. In the crystal, the A and B molecules are linked via a C—H...N hydrogen bond. They stack along the b -axis direction forming columns within which there are weak π–π interactions present [shortest inter-centroid distance = 3.6933 (13) Å].
    Preview · Article · Dec 2015
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    ABSTRACT: In the present study, a series of steroidal tetrazole derivatives of androstane and pregnane have been prepared in which the tetrazole moiety was appended at C-3 and 17a-aza locations. 3-Tetrazolo-3,5-androstadien-17-one (6), 3-tetrazolo-19-nor-3,5-androstadien-17-one (10), 3-tetrazolo-3,5-pregnadien-20-one (14), 17a-substituted 3-tetrazolo-17a-aza-d-homo-3,5-androstadien-17-one (26–31) and 3-(2-acetyltetrazolo)-17a-aza-d-homo-3,5-androstadien-17-one (32) were synthesized from dehydroepiandrosterone acetate (1) through multiple synthetic steps. Some of the synthesized compounds were evaluated for their in vitro 5α-reductase (5AR) inhibitory activity by measuring the conversion of [3H] androstenedione in human embryonic kidney (HEK) cells. In vivo 5α-reductase inhibitory activity also showed a significant reduction (p <0.05) in rat prostate weight. The most potent compound 14 showed 5AR-2 inhibition with IC50 being 15.6 nM as compared to clinically used drug finasteride (40 nM). There was also a significant inhibition of 5AR-1 with IC50 547 nM compared to finasteride (453 nM).
    No preview · Article · Dec 2015 · Bioorganic & medicinal chemistry
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    ABSTRACT: Four different classes of new 17β-hydroxysteroid dehydrogenase type 2 (17β-HSD2) inhibitors were synthesized, in order to lower the cytotoxicity exhibited by the lead compound A, via disrupting the linearity and the aromaticity of the biphenyl moiety. Compounds 3, 4, 7a and 8 displayed comparable or better inhibitory activity and selectivity, as well as a lower cytotoxic effect, compared to the reference compound A. The best compound 4 (IC50=160nM, selectivity factor=168, LD50≈25μM) turned out as new lead compound for inhibition of 17β-HSD2.
    Full-text · Article · Nov 2015 · Bioorganic & medicinal chemistry letters
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    ABSTRACT: Typically, 4,6-disubstituted 2-thiomethylpyrimidines are synthesized starting from 4,6-dichloro-2-thiomethylpyrimidine or an amino-substituted precursor. However, these reactions take several hours up to days and require multiple steps. Herein, we report a novel, easy, and quick-to-prepare synthetic intermediate, namely 2-(methylthio)-4,6-di(1H-tetrazol-1-yl)pyrimidine, for the synthesis of these interesting target compounds. The intermediate can be transformed within minutes into desired substituted pyrimidines under mild conditions with moderate to excellent yields. The reaction can be conducted in an automated microwave system, at room temperature or by conventional heating. Furthermore, we demonstrate the robustness of the method in a one-pot procedure.
    No preview · Article · Oct 2015 · Synlett
  • A Thomann · J Zapp · M Hutter · M Empting · R W Hartmann
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    ABSTRACT: This paper focuses on an interesting constitutional isomerism called azido-tetrazole equilibrium which is observed in azido-substituted N-heterocycles. We present a systematic investigation of substituent effects on the isomer ratio within a 2-substituted 4-azidopyrimidine model scaffold. NMR- and IR-spectroscopy as well as X-ray crystallography were employed for thorough analysis and characterization of synthesized derivatives. On the basis of this data, we demonstrate the possibility to steer this valence tautomerism towards the isomer of choice by means of substituent variation. We show that the tetrazole form can act as an efficient disguise for the corresponding azido group masking its well known reactivity in azide-alkyne cycloadditions (ACCs). In copper(i)-catalyzed AAC reactions, substituent-stabilized tetrazoles displayed a highly decreased or even abolished reactivity whereas azides and compounds in the equilibrium were directly converted. By use of an acid sensitive derivative, we provide, to our knowledge, the first experimental basis for a possible exploitation of this dynamic isomerism as a pH-dependent azide-protecting motif for selective SPAAC conjugations in aqueous media. Finally, we demonstrate the applicability and efficiency of stabilized tetrazolo[1,5-c]pyrimidines for Fragment-Based Drug Design (FBDD) in the field of quorum sensing inhibitors.
    No preview · Article · Sep 2015 · Organic & Biomolecular Chemistry
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    Dataset: mmc1

    Full-text · Dataset · Aug 2015
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    ABSTRACT: Design and synthesis of a new class of inhibitors for the treatment of osteoporosis and its comparative h17β-HSD2 and m17β-HSD2 SAR study are described. 17a is the first compound to show strong inhibition of both h17β-HSD2 and m17β-HSD2, intracellular activity, metabolic stability, selectivity toward h17β-HSD1, m17β-HSD1 and estrogen receptors α and β as well as appropriate physicochemical properties for oral bioavailability. These properties make it eligible for pre-clinical animal studies, prior to human studies.
    Full-text · Article · Jul 2015 · PLoS ONE
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    Full-text · Dataset · Jul 2015
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    ABSTRACT: Hit-to-lead efforts resulted in the discovery of compound 19, a potent CYP11B2 inhibitor that displays high selectivity vs related CYPs, good pharmacokinetic properties in rat and rhesus, and lead-like physical properties. In a rhesus pharmacodynamic model, compound 19 displays robust, dose-dependent aldosterone lowering efficacy, with no apparent effect on cortisol levels.
    Full-text · Article · Jul 2015 · ACS Medicinal Chemistry Letters
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    ABSTRACT: The aim of this work was to develop clarithromycin microparticles (CLARI-MP) and evaluate their aerodynamic behavior, safety in bronchial cells and anti-bacterial efficacy. Microparticles containing clarithromycin were prepared as dry powder carrier for inhalation, using leucine and chitosan. CLARI-MP were deposited on Calu-3 grown at air-interface condition, using the pharmaceutical aerosol deposition device on cell cultures (PADDOCC). Deposition efficacy, transport across the cells and cytotoxicity were determined. Anti-antibacterial effect was evaluated against Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. Microparticles were of spherical shape, smooth surface and size of about 765 nm. Aerosolization performance showed a fine particle fraction (FPF) of 73.3%, and a mass median aerodynamic diameter (MMAD) of 1.8 μm. Deposition on Calu-3 cells using the PADDOCC showed that 8.7 μg/cm(2) of deposited powder were transported to the basolateral compartment after 24 h. The safety of this formulation is supported by the integrity of the cellular epithelial barrier and absence of toxicity, and the antimicrobial activity demonstrated for Gram positive and Gram negative bacteria. The appropriate aerodynamic properties and the excellent deposition on Calu-3 cells indicate that clarithromycin microparticles are suitable for administration via pulmonary route and are efficient to inhibit bacteria proliferation.
    Full-text · Article · Jun 2015 · Pharmaceutical Research
  • Chris J van Koppen · Rolf W Hartmann
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    ABSTRACT: Introduction: About 2% of the Western world population suffer from chronic wounds, resulting from underlying disorders (e.g., diabetes, excessive pressure, vascular insufficiencies and vasculitis), with a significant adverse effect on Quality of Life. Despite high incidence and economic burden, management of chronic wounds is still far from effective and novel therapies are in urgent need. Wound healing is a dynamic process of transient expression, function and clearance of mediators, enzymes and cell types. Failure to initiate, terminate or regulate leads to pathologic wound healing. Areas covered: The present review discusses patents of the seven most promising classes of biological agents, mostly published in 2009 - 2014 (CYP11B1 inhibitors, peptide growth factors, prolyl-4-hydroxylase and matrix metalloproteinase inhibitors, bone marrow-derived mesenchymal stem cells, elastase and connexin43 inhibitors). Relevant information from peer-reviewed journals is also presented. Expert opinion: The aforementioned biological agents have different mechanisms of action, and considering the multifactorial pathogenesis of chronic wounds, they hold promise in treating chronic wounds. However, as administration of a certain biological agent may be beneficial in an early phase, it may slow down wound healing in a later phase. Basic and clinical research on chronic wound healing should therefore investigate the efficacy of these agents, alone and in concert, during the consecutive phases of wound healing.
    No preview · Article · Jun 2015 · Expert Opinion on Therapeutic Patents
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    ABSTRACT: Loop diuretics are used for fluid control in patients with heart failure. Furosemide and torasemide may exert differential effects on myocardial fibrosis. Here, we studied the effects of torasemide and furosemide on atrial fibrosis and remodeling during atrial fibrillation METHODS AND RESULTS: In primary neonatal cardiac fibroblasts, torasemide (50 μM, 24 h) but not furosemide (50 μM, 24 h) reduced the expression of connective tissue growth factor (CTGF; 65±6%) and the pro-fibrotic miR-21 (44±23%), as well as the expression of lysyl oxidase (LOX; 57±8%), a regulator of collagen crosslinking. Mineralocorticoid receptor (MR) expression and activity were not altered. Torasemide but not furosemide inhibited human aldosterone synthase (CYP11B2) activity in transfected lung fibroblasts (V79MZ cells) by 75±1.8%. The selective CYP11B2 inhibitor SL242 mimicked the torasemide effects. Mice with cardiac overexpression of Rac1 GTPase (RacET), which develop atrial fibrosis and spontaneous AF with aging, were treated long-term (8 months) with torasemide (10mg/kg/day), furosemide (40mg/kg/day) or vehicle. Treatment with torasemide but not furosemide prevented atrial fibrosis in RacET as well as the up-regulation of CTGF, LOX and miR-2, whereas MR expression and activity remained unaffected. These effects correlated with a reduced prevalence of atrial fibrillation (33% RacET+Tora vs. 80% RacET). Torasemide but not furosemide inhibits CYP11B2 activity and reduces the expression of CTGF, LOX and miR-21. These effects are associated with prevention of atrial fibrosis and a reduced prevalence of atrial fibrillation in mice. Copyright © 2015. Published by Elsevier Ltd.
    No preview · Article · Jun 2015 · Journal of Molecular and Cellular Cardiology
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    ABSTRACT: Pseudomonas aeruginosa employs a quorum sensing (QS) communication system that makes use of small diffusible molecules. Among other effects, the QS system coordinates the formation of biofilm which decisively contributes to difficulties in the therapy of Pseudomonas infections. The present work deals with the structure-activity exploration of ureidothiophene-2-carboxylic acids as inhibitors of PqsD, a key enzyme in the biosynthetic pathway of signal molecules in the Pseudomonas QS system. We describe an improvement of the inhibitory activity by successfully combining features from two different PqsD inhibitor classes. Furthermore the functional groups, which are responsible for the inhibitory potency, were identified. Moreover, the inability of the new inhibitors, to prevent signal molecule formation in whole cell assays, is discussed. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    No preview · Article · May 2015 · European Journal of Medicinal Chemistry
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    Qingzhong Hu · Jessica Kunde · Nina Hanke · Rolf W. Hartmann
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    ABSTRACT: The inhibition of 11β-hydroxylase is a promising strategy for the treatment of Cushing's syndrome, in particular for the recurrent and subclinical cases. To achieve proof of concept in rats, efforts were paid to identify novel lead compounds inhibiting both human and rat CYP11B1. Modifications on a potent promiscuous inhibitor of hCYP11B1, hCYP11B2 and hCYP19 (compound IV) that exhibited moderate rCYP11B1 inhibition led to compound 8 as a new promising lead compound. Significant improvements compared to starting point IV were achieved regarding inhibitory potency against both human and rat CYP11B1 (IC50 values of 2 and 163 nM, respectively) as well as selectivity over hCYP19 (IC50 = 1900 nM). Accordingly, compound 8 was around 7- and 28-fold more potent than metyrapone regarding the inhibition of human and rat CYP11B1 and exhibited a comparable selectivity over hCYP11B2 (SF of 3.5 vs 4.9). With further optimizations on this new lead compound 8, drug candidates with satisfying profiles are expected to be discovered. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    Full-text · Article · May 2015 · European Journal of Medicinal Chemistry
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    ABSTRACT: The first total synthesis of cystobactamid 507, a member of a class of new natural products with strong inhibitory activity towards bacterial topoisomerases, is reported. Synthetic key challenges are the central tetrasubstitued arene and the low chemical reactivity of anilines and ortho-phenolic and isopropoxy-substituted benzoic acids. Biological evaluations demonstrate that cystobactamid 507 inhibits several Gram-positive pathogens but at significantly lower concentrations than described for the larger members of this natural product family.
    No preview · Article · May 2015 · Synlett
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    ABSTRACT: Myxopyronins are α-pyrone antibiotics produced by the terrestrial bacterium Myxococcus fulvus Mx f50 and possess antibacterial activity against Gram-positive and Gram-negative pathogens. They target the bacterial RNA polymerase (RNAP) “switch region” as non-competitive inhibitors and display no cross-resistance to the established RNAP inhibitor rifampicin. Recent analysis of the myxopyronin biosynthetic pathway lead to the hypothesis that this secondary metabolite is produced from two separate polyketide parts, which are condensed by the stand-alone ketosynthase MxnB. Using in vitro assays we show that MxnB catalyzes a unique condensation reaction forming the α-pyrone ring of myxopyronins from two activated acyl chains in form of their β-keto intermediates. MxnB is able to accept thioester substrates coupled to either N-acetylcysteamine (NAC) or a specific carrier protein (CP). The turnover rate of MxnB for substrates bound to CP was 12-fold higher than for SNAC substrates, demonstrating the importance of protein-protein interactions in multimodular polyketide synthases (PKSs). The crystal structure of MxnB reveals the enzyme to be an unusual member of the ketosynthase group capable of binding and condensing two long alkyl chains bound to carrier proteins. The geometry of the two binding tunnels supports the biochemical data and allows us to propose an order of reaction, which is supported by the identification of novel myxopyronin congeners in the extract of the producer strain. Insights into the mechanism of this unique condensation reaction do not only expand our knowledge regarding the thiolase enzyme family but also opens up opportunities for PKS bioengineering to achieve directed structural modifications.
    No preview · Article · May 2015 · Chemical Science
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    ABSTRACT: Myxopyronin is a natural α-pyrone antibiotic from the soil bacterium Myxococcus fulvus Mx f50. Myxopyronin inhibits bacterial RNA polymerase (RNAP) by binding to a part of the enzyme not targeted by the clinically used rifamycins. This mode of action makes myxopyronins promising molecules for the development of novel broad-spectrum antibacterials. We describe the derivatization of myxopyronins by an advanced mutasynthesis approach as a first step towards this goal. Site-directed mutagenesis of the biosynthetic machinery was used to block myxopyronin biosynthesis at different stages. The resulting mutants were fed with diverse precursors that mimic the biosynthetic intermediates to restore production. Mutasynthon incorporation and production of novel myxopyronin derivatives were analyzed by HPLC-MS/MS. This work sets the stage for accessing numerous myxopyronin derivatives, thus significantly expanding the chemical space of f α-pyrone antibiotics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    No preview · Article · Mar 2015 · ChemBioChem
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    ABSTRACT: CYP11B2 inhibition is a promising treatment for diseases caused by excessive aldosterone. To improve the metabolic stability in human liver miscrosomes of previously reported CYP11B2 inhibitors, scaffold hopping was performed via a combination of ligand- and structure-based drug design approaches leading to pyridyl 4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolones. Compound 26 not only exhibited a much longer half-life (t1/2 > 120 min), but also sustained inhibitory potency (IC50 = 4.2 nM) and selectivity over CYP11B1 (SF = 422), CYP17, CYP19 and a panel of hepatic CYP enzymes.
    Full-text · Article · Feb 2015 · Journal of Medicinal Chemistry

Publication Stats

6k Citations
1,103.80 Total Impact Points

Institutions

  • 1990-2016
    • Universität des Saarlandes
      • Pharmazeutische und Medizinische Chemie
      Saarbrücken, Saarland, Germany
    • Freie Universität Berlin
      • Institute of Pharmacy
      Berlín, Berlin, Germany
  • 2010-2015
    • Helmholtz Institute for Pharmaceutical Research Saarland
      • Department of Microbial Natural Products
      Saarbrücken, Saarland, Germany
    • University of Vienna
      Wien, Vienna, Austria
  • 1980-2010
    • Universität Regensburg
      • • Institute of Pharmacy
      • • Lehrstuhl für Pharmazeutische Chemie II
      Ratisbon, Bavaria, Germany
  • 2006-2007
    • University of Bologna
      • Department of Pharmacy and Biotechnology FaBiT
      Bolonia, Emilia-Romagna, Italy
  • 2005
    • Panjab University
      Chandigarh, Chandigarh, India
    • Università degli Studi di Bari Aldo Moro
      • Dipartimento di Farmacia - Scienze del Farmaco
      Bari, Apulia, Italy