Rolf W Hartmann

Helmholtz Institute for Pharmaceutical Research Saarland, Saarbrücken, Saarland, Germany

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Publications (338)986.73 Total impact

  • [Show abstract] [Hide abstract]
    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.
    European Journal of Medicinal Chemistry 05/2015; 96. DOI:10.1016/j.ejmech.2015.04.007 · 3.43 Impact Factor
  • 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.
    European Journal of Medicinal Chemistry 05/2015; 96. DOI:10.1016/j.ejmech.2015.04.013 · 3.43 Impact Factor
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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.
    ChemBioChem 03/2015; DOI:10.1002/cbic.201402666 · 3.06 Impact Factor
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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.
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    ABSTRACT: 1-Phenylsulfinyl-3-(pyridin-3-yl)naphthalen-2-ols and related compounds were synthesized and evaluated for inhibition of aldosterone synthase (CYP11B2), a potential target for cardiovascular diseases associated with elevated plasma aldosterone levels like congestive heart failure and myocardial fibrosis. Introduction of substituents at the phenylsulfinyl moiety and changes of the substitution pattern at the naphthalene core were examined. Potent compounds were further examined for selectivity versus other important steroidogenic CYP enzymes, i.e. the highly homologous 11 beta-hydroxylase (CYP11B1), CYP17 and CYP19. The most potent compound (IC50 = 14 nM) discovered was the meta-trifluoromethoxy derivative 11, which also exhibited excellent selectivity toward CYP11B1 (SF = 415), and showed no inhibition of CYP17 and CYP19.
    European Journal of Medicinal Chemistry 01/2015; 89. DOI:10.1016/j.ejmech.2014.10.027 · 3.43 Impact Factor
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    ABSTRACT: Diseases triggered by an abnormally high level of cortisol (hypercortisolism), such as the Cushing's and metabolic syndromes, could be successfully tackled by inhibitors of CYP11B1, a steroidal cytochrome P450 enzyme that catalyzes the last hydroxylation step of the cortisol biosynthesis. Structural optimization of 7-(benzyloxy)-4-(1H-imidazol-1-ylmethyl)-2H-chromen-2-one 2, a selective aromatase inhibitor, afforded the 4-(1H-imidazol-1-ylmethyl)-7-{[3-(trifluoromethoxy)benzyl]oxy}-2H-chromen-2-one 7, with improved inhibitory potency at human CYP11B1 (IC50 = 5 nM) and an enhanced selectivity over human CYP11B2 (SIB = 25) compared to lead compound 2 (IC50 = 72 nM, SIB = 4.0) and metyrapone (IC50 = 15 nM, SIB = 4.8), a non-selective drug used in the therapy of the Cushing's syndrome. Structure-activity relationship studies allowed the design and optimization of a novel series of potent and selective compounds, that can be regarded as open analogues of 2H-chromen-2-one derivatives. Compound 23, 2-(1H-imidazol-1-yl)-1-(4-{[3(trifluoromethoxy)benzyl]oxy}phenyl) ethanone, was the most interesting inhibitor of the series displaying a high potency at CYP11B1 (IC50 = 15 nM), increased selectivities over CYP11B2 (SIB = 33), CYP19 (SIB = 390) and CYP17 (5% inhibition at 2.5 μM concentration). Copyright © 2014 Elsevier Masson SAS. All rights reserved.
    European Journal of Medicinal Chemistry 01/2015; 89:106–114. DOI:10.1016/j.ejmech.2014.10.021 · 3.43 Impact Factor
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    ABSTRACT: Aldosterone synthase (CYP11B2) catalyzes the conversion of 11-deoxycorticosterone to aldosterone via corticosterone and 18-hydroxycorticosterone. CYP11B2 is regarded as a new target for several cardiovascular diseases which are associated with chronically elevated aldosterone levels such as hypertension, congestive heart failure and myocardial fibrosis. In this paper, we optimized heterocycle substituted 3,4-dihydropyridin-2(1H)-ones as CYP11B inhibitors by systematic introduction of heteroatoms and by bioisosteric exchange of the lactame moiety by a sultame moiety. The most promising compounds regarding inhibition of human CYP11B2 and selectivity versus human enzymes CYP11B1, CYP17, and CYP19 were tested for inhibition of rat CYP11B2. Thus, we discovered compounds 4 and 9 which show potent inhibition of hCYP11B2 (IC50 < 1 nM) and the corresponding rat enzyme (4: 64%, 9: 51% inhibition, at 2 μM). Copyright © 2014. Published by Elsevier Masson SAS.
    European Journal of Medicinal Chemistry 12/2014; 90C:788-796. DOI:10.1016/j.ejmech.2014.12.022 · 3.43 Impact Factor
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    ABSTRACT: A new series of pregnenonlone analogs were synthesized and evaluated for their inhibitory activity against cytochrome P450 (CYP17 hydroxylase enzyme). In general, the 5-aryl-1,3,4-thiadiazol-2-yl)-imino-pregnenolone derivatives 11–15 were more active than the sulfonate 24–31 and the ester 37–41 analogs. Derivative 12 showed optimal activity in this series, with IC50 values of 2.5 µM compared with the standard abiraterone (IC50 = 0.07 µM). However, the analogs 11 and 25 showed a better selectivity profile (81.5 and 82.7% inhibition of hydroxylase, respectively), which may be a useful lead in CYP17 inhibition studies. Molecular docking studies demonstrated quite similar binding patterns of all new pregnenolone derivatives at the active site of CYP17 through hydrogen bonding and hydrophobic interaction.
    Archiv der Pharmazie 12/2014; 347(12). DOI:10.1002/ardp.201400255 · 1.40 Impact Factor
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    ABSTRACT: In order to identify new scaffolds for drug discovery, surface plasmon resonance is frequently used to screen structurally diverse libraries. Usually, hit rates are low and identification processes are time consuming. Hence, approaches which improve hit rates and, thus, reduce the library size are required. In this work, we studied three often used strategies for their applicability to identify inhibitors of PqsD. In two of them, target-specific aspects like inhibition of a homologous protein or predicted binding determined by virtual screening were used for compound preselection. Finally, a fragment library, covering a large chemical space, was screened and served as comparison. Indeed, higher hit rates were observed for methods employing preselected libraries indicating that target-oriented compound selection provides a time-effective alternative.
    Future medicinal chemistry 12/2014; 6(18):2057-72. DOI:10.4155/fmc.14.142 · 4.00 Impact Factor
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    ABSTRACT: A new strategy for treating Pseudomonas aeruginosa infections could be disrupting the Pseudomonas Quinolone Signal (PQS) quorum sensing (QS) system. The goal is to impair communication among the cells and, hence, reduce the expression of virulence factors and the formation of biofilms. PqsD is an essential enzyme for the synthesis of PQS and shares some features with chalcone synthase (CHS2), an enzyme expressed in Medicago sativa. Both proteins are quite similar concerning the size of the active site, the catalytic residues and the electrostatic surface potential at the entrance of the substrate tunnel. Hence, we evaluated selected substrates of the vegetable enzyme as potential inhibitors of the bacterial protein. This similarity-guided approach led to the identification of a new class of PqsD inhibitors having a catechol structure as an essential feature for activity, a saturated linker with two or more carbons and an ester moiety bearing bulky substituents. The developed compounds showed PqsD inhibition with IC50 values in the single-digit micromolar range. The binding mode of these compounds was investigated by Surface Plasmon Resonance (SPR) experiments revealing that their interaction with the protein is not influenced by the presence of the anthranilic acid bound to active site cysteine. Importantly, some compounds reduced the signal molecule production in cellulo. Copyright © 2014. Published by Elsevier Masson SAS.
    European Journal of Medicinal Chemistry 11/2014; 90C:351-359. DOI:10.1016/j.ejmech.2014.11.055 · 3.43 Impact Factor
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  • ChemInform 11/2014; 45(45). DOI:10.1002/chin.201445185
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    ABSTRACT: The inhibition of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1), which catalyzes the conversion of estrone into the potent estrogen receptor agonist estradiol (E2), is discussed as a novel therapeutic approach for the treatment of estrogen-dependent diseases. Because the reduction of E2 would be basically limited to the target tissues, this approach is expected to cause fewer side effects than the currently employed antihormonal therapies. Recently, we reported on 6-hydroxybenzothiazole ketones as a new class of 17β-HSD1 inhibitors with a notable activity/selectivity profile. In an attempt to further optimize these parameters, we modified the benzothiazole core by a systematic bioisosteric replacement. Thus, we were able to identify a new 6-hydroxybenzothiophene derivative that displayed stronger inhibition of 17β-HSD1 (IC50=13 nM) and that was also more selective than a benzothiazole analog. Using ab initio calculations, we found that the higher potency of the 6-hydroxybenzothiophene derivative was probably due to more favorable conformational preorganization of the scaffold for binding to the enzyme.
    ChemMedChem 10/2014; 9(10). DOI:10.1002/cmdc.201402050 · 3.05 Impact Factor
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    ABSTRACT: In Alzheimer's disease (AD), multiple factors account for the accumulation of neurocellular changes, which may begin several years before symptoms appear. The most important pathogenic brain changes that are contributing to the development of AD are the formation of the cytotoxic β-amyloid aggregates and of the neurofibrillary tangles, which originate from amyloid-β peptides and hyperphosphorylated tau protein, respectively. New therapeutic agents that target both major pathogenic mechanisms may be particularly efficient. In this study, we introduce bis(hydroxyphenyl)-substituted thiophenes as a novel class of selective, dual inhibitors of the tau kinase Dyrk1A and of the amyloid-β aggregation.
    ACS Chemical Neuroscience 09/2014; DOI:10.1021/cn5001815 · 4.21 Impact Factor
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    ABSTRACT: 17β-HSD2 is a promising new target for the treatment of osteoporosis. In this paper, a rational strategy to overcome the metabolic liability in the 2,5-thiophene amide class of 17β-HSD2 inhibitors is described, and the biological activity of the new inhibitors. Applying different strategies, as lowering the cLogP or modifying the structures of the molecules, compounds 27, 31 and 35 with strongly improved metabolic stability were obtained. For understanding biotransformation in the 2,5-thiophene amide class the main metabolic pathways of three properly selected compounds were elucidated.
    European Journal of Medicinal Chemistry 09/2014; 87:203-219. DOI:10.1016/j.ejmech.2014.09.061 · 3.43 Impact Factor
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    ABSTRACT: Dysregulated usage of pre-mRNA splicing sites contributes to the progression of cancer, neurodegenerative diseases, and viral infections. Serine/arginine-rich (SR) proteins play major roles in the splice site recognition and are largely regulated by phosphorylation. This provides an option for the pharmacological correction of aberrant splicing by inhibiting the relevant kinases. Cdc2-like kinases (Clks) and dual specificity tyrosine phosphorylation-regulated kinases (Dyrks) were both reported to phosphorylate numerous SR proteins in vitro and in vivo. In this study, we describe the discovery of new selective dual Clk/Dyrk1A/1B inhibitors, which are able to modulate alternative pre-mRNA splicing of model gene transcripts in cells with submicromolar potencies. The optimization process yielded a dual Clk and Dyrk inhibitor with exceptionally high ligand efficiency. Our results suggested that dual inhibition of both Clk1 and Dyrk1A increased the efficacy of pre-mRNA splicing modulation.
    ACS Medicinal Chemistry Letters 09/2014; 5(9):963-7. DOI:10.1021/ml500059y · 3.07 Impact Factor
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    ABSTRACT: The bacterial RNA polymerase (RNAP) represents a validated target for the development of broad-spectrum antibiotics. However, the medical value of RNAP inhibitors in clinical use is limited by the prevalence of resistant strains. To overcome this problem, we focused on the exploration of alternative target sites within the RNAP. Previously, we described the discovery of a novel RNAP inhibitor class containing an ureidothiophene-2-carboxylic acid core structure. Herein, we demonstrate that these compounds are potent against a set of methicillin-resistant Staphylococcus aureus (MRSA) strains (MIC: 2-16 μg ml-1) and rifampicin-resistant Escherichia coli TolC strains (MIC: 12.5-50 μg ml-1). Additionally, an abortive transcription assay revealed that these compounds inhibit the bacterial transcription process during the initiation phase. Furthermore, the binding mode of the ureidothiophene-2-carboxylic acids was characterized by mutagenesis studies and ligand-based NMR spectroscopy. Competition saturation transfer difference (STD) NMR experiments with the described RNAP inhibitor myxopyronin A (Myx) suggest that the ureidothiophene-2-carboxylic acids compete with Myx for the same binding site in the RNAP switch region. INPHARMA (Interligand NOE for PHARmacophore MApping) experiments and molecular docking simulations provided a binding model in which the ureidothiophene-2-carboxylic acids occupy the region of the Myx western chain binding site and slightly occlude that of the eastern chain. These results demonstrate that the ureidothiophene-2-carboxylic acids are a highly attractive new class of RNAP inhibitors that can avoid the problem of resistance.
    ACS Chemical Biology 09/2014; DOI:10.1021/cb5005433 · 5.36 Impact Factor
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    ABSTRACT: Antibiotic resistance has become a major health problem. The σ(70):core interface of bacterial RNA polymerase is a promising drug target. Recently, the coiled-coil and lid-rudder-system of the β' subunit has been identified as an inhibition hot spot. Materials & methods & Results: By using surface plasmon resonance-based assays, inhibitors of the protein-protein interaction were identified and competition with σ(70) was shown. Effective inhibition was verified in an in vitro transcription and a σ(70):core assembly assay. For one hit series, we found a correlation between activity and affinity. Mutant interaction studies suggest the inhibitors' binding site.
    Future medicinal chemistry 09/2014; 6(14):1551-65. DOI:10.4155/fmc.14.105 · 4.00 Impact Factor
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    ABSTRACT: Topical application of CYP11B1 inhibitors to reduce cutaneous cortisol is a novel strategy to promote healing of chronic wounds. Pyridyl substituted arylsulfonyltetrahydroquinolines were designed and synthesized resulting in a strong inhibitor 34 (IC50 = 5 nM). It showed no inhibition of CYP17 and CYP19 and no mutagenic effects. It exhibited inverse metabolic stability in plasma (t1/2 > 150 min), which is similar to wound fluid in composition, and in liver S9 fractions (t1/2 = 16 min).
    Journal of Medicinal Chemistry 08/2014; 57(18). DOI:10.1021/jm501004t · 5.48 Impact Factor
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    ABSTRACT: FULL PAPER Martin Empting, Rolf W. Hartmann et al. From in vitro to in cellulo: structure–activity relationship of (2-nitrophenyl)- methanol derivatives as inhibitors of PqsD in Pseudomonas aeruginosa

Publication Stats

4k Citations
986.73 Total Impact Points

Institutions

  • 2010–2015
    • Helmholtz Institute for Pharmaceutical Research Saarland
      • Department of Microbial Natural Products
      Saarbrücken, Saarland, Germany
    • University of Vienna
      Wien, Vienna, Austria
  • 1990–2015
    • Universität des Saarlandes
      • Pharmazeutische und Medizinische Chemie
      Saarbrücken, Saarland, Germany
    • Freie Universität Berlin
      • Institute of Pharmacy
      Berlín, Berlin, Germany
  • 2001–2007
    • University of Bologna
      • Department of Pharmacy and Biotechnology FaBiT
      Bolonia, Emilia-Romagna, Italy
  • 2005
    • Università degli Studi di Bari Aldo Moro
      • Dipartimento di Farmacia - Scienze del Farmaco
      Bari, Apulia, Italy
  • 1998
    • University of Wales
      • Welsh School of Pharmacy
      Cardiff, Wales, United Kingdom
  • 1980–1987
    • Universität Regensburg
      • • Institute of Pharmacy
      • • Lehrstuhl für Pharmazeutische Chemie II
      Ratisbon, Bavaria, Germany