• 1-Phenylsulfinyl-3-(pyridin-3-yl)naphthalen-2-ols: a new class of potent and selective aldosterone synthase inhibitors.

      Grombein, Cornelia M; Hu, Qingzhong; Heim, Ralf; Rau, Sabrina; Zimmer, Christina; Hartmann, Rolf W; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarland University, Campus C23, D-66123 Saarbrücken, Germany. (2015-01-07)
      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 11β-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.
    • Benzamidobenzoic acids as potent PqsD inhibitors for the treatment of Pseudomonas aeruginosa infections.

      Hinsberger, Stefan; de Jong, Johannes C; Groh, Matthias; Haupenthal, Jörg; Hartmann, Rolf W (2014-04-09)
      Targeting PqsD is a promising novel approach to disrupt bacterial cell-to-cell-communication in Pseudomonas aeruginosa. In search of selective PqsD inhibitors, two series of benzamidobenzoic acids - one published as RNAP inhibitors and the other as PqsD inhibitors - were investigated for inhibitory activity toward the respective other enzyme. Additionally, novel derivatives were synthesized and biologically evaluated. By this means, the structural features needed for benzamidobenzoic acids to be potent and, most notably, selective PqsD inhibitors were identified. The most interesting compound of this study was the 3-Cl substituted compound 5 which strongly inhibits PqsD (IC₅₀ 6.2 μM) while exhibiting no inhibition of RNAP.
    • Catechol-based substrates of chalcone synthase as a scaffold for novel inhibitors of PqsD.

      Allegretta, Giuseppe; Weidel, Elisabeth; Empting, Martin; Hartmann, Rolf W; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), PO Box 15 11 50, D-66041 Saarbrücken, Germany. (2015-01-27)
      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.
    • Discovery of new 7-substituted-4-imidazolylmethyl coumarins and 4'-substituted-2-imidazolyl acetophenones open analogues as potent and selective inhibitors of steroid-11β-hydroxylase.

      Stefanachi, Angela; Hanke, Nina; Pisani, Leonardo; Leonetti, Francesco; Nicolotti, Orazio; Catto, Marco; Cellamare, Saverio; Hartmann, Rolf W; Carotti, Angelo; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), PO Box 15 11 50, D-66041 Saarbrücken, Germany. (2015-01-07)
      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).
    • Drifting of heme-coordinating group in imidazolylmethylxanthones leading to improved selective inhibition of CYP11B1.

      Gobbi, Silvia; Hu, Qingzhong; Zimmer, Christina; Belluti, Federica; Rampa, Angela; Hartmann, Rolf W.; Bisi, Alessandra; HIPS, Helmholtz Institut für pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2017-08-02)
      An abnormal increase in glucocorticoid levels is responsible for pathological disorders affecting different organs and systems, and the selective inhibition of appropriate steroidogenic enzymes represents a validated strategy to restore their physiological levels. In continuing our studies on CYP11B inhibitors, in this paper a small series of 6-substituted 3-imidazolylmethylxanthones was designed and synthesized, according to the data acquired from previously reported series of derivatives and from a purposely-performed docking study. The new compounds proved to be potent inhibitors of CYP11B isoforms, being effective on CYP11B1 in the low nanomolar range and improving selectivity with respect to CYP11B2, compared to previously reported related compounds. These data further confirmed that a suitable mutual arrangement of the imidazolylmethyl pharmacophore and a properly selected substituent on the xanthone core allows a fine tuning of the activity towards the different CYPs and further corroborate the role of the xanthone scaffold as a privileged structure in this field.
    • Exploring the chemical space of ureidothiophene-2-carboxylic acids as inhibitors of the quorum sensing enzyme PqsD from Pseudomonas aeruginosa.

      Sahner, J Henning; Empting, Martin; Kamal, Ahmed; Weidel, Elisabeth; Groh, Matthias; Börger, Carsten; Hartmann, Rolf W; Pharmaceutical and Medicinal Chemistry, Saarland University & Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Department of Drug Design and Optimization, Campus C2 3, 66123 Saarbrücken, Germany. (2015-05-26)
      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.
    • Heteroatom insertion into 3,4-dihydro-1H-quinolin-2-ones leads to potent and selective inhibitors of human and rat aldosterone synthase.

      Grombein, Cornelia M; Hu, Qingzhong; Rau, Sabrina; Zimmer, Christina; Hartmann, Rolf W; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) Campus C2 3, D-66123 Saarbrücken, Germany. (2015-01-27)
      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).
    • Hit-to-lead optimization of a latency-associated nuclear antigen inhibitor against Kaposi's sarcoma-associated herpesvirus infections.

      Kirsch, Philine; Stein, Saskia C; Berwanger, Aylin; Rinkes, Julia; Jakob, Valentin; Schulz, Thomas F; Empting, Martin; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Elsevier, 2020-06-28)
      The Latency-associated nuclear antigen (LANA) plays a central role for the latent persistence of the Kaposi's Sarcoma Herpesvirus (KSHV) in the human host and helps to establish lifelong infections. Herein, we report our efforts towards hit-to-lead generation starting from a previously discovered LANA-DNA inhibitor. By tethering the viral genome to the host nucleosomes, LANA ensures the segregation and persistence of the viral DNA during mitosis. LANA is also required for the replication of the latent viral episome during the S phase of the cell cycle. We aim to inhibit the interaction between LANA and the viral genome to prevent the latent persistence of KSHV in the host organism. Medicinal chemistry-driven optimization studies and structure-activity-relationship investigation led to the discovery of an improved LANA inhibitor. The functional activity of our compounds was evaluated using a fluorescence polarization (FP)-based interaction inhibition assay and electrophoretic mobility shift assay (EMSA). Even though a crystal structure of the ligand protein complex was not available, we successfully conducted hit optimization toward a low micromolar protein-nucleic acid-interaction inhibitor. Additionally, we applied STD-NMR studies to corroborate target binding and to gain insights into the binding orientation of our most potent inhibitor, providing opportunities for further rational design of more efficient LANA-targeting anti KSHV agents in future studies.
    • Identification of 4-(4-nitro-2-phenethoxyphenyl)pyridine as a promising new lead for discovering inhibitors of both human and rat 11β-Hydroxylase.

      Hu, Qingzhong; Kunde, Jessica; Hanke, Nina; Hartmann, Rolf W; Pharmaceutical and Medicinal Chemistry, Saarland University, Campus C2.3, D-66123 Saarbrücken, Germany. (2015-05-26)
      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.
    • Inhibition of 17β-HSD1: SAR of bicyclic substituted hydroxyphenylmethanones and discovery of new potent inhibitors with thioether linker.

      Abdelsamie, Ahmed S; Bey, Emmanuel; Hanke, Nina; Empting, Martin; Hartmann, Rolf W; Frotscher, Martin (2014-07-23)
      Estradiol is the most potent estrogen in humans. It is known to be involved in the development and proliferation of estrogen dependent diseases such as breast cancer and endometriosis. The last step of its biosynthesis is catalyzed by 17β-hydroxysteroid dehydrogenase type 1 (17β- HSD1) which consequently is a promising target for the treatment of these diseases. Recently, we reported on bicyclic substituted hydroxyphenylmethanones as potent inhibitors of 17β-HSD1. The present study focuses on rational structural modifications in this compound class with the aim of gaining more insight into its structure-activity relationship (SAR). (4-Hydroxyphenyl)-(5-(3-hydroxyphenylsulfanyl)-thiophen-2-yl)methanone (25) was discovered as a member of a novel potent class of human 17β-HSD1 inhibitors. Computational methods were used to elucidate its interactions with the target protein. The compound showed activity also towards the murine 17β-HSD1 enzyme and thus is a starting point for the design of compounds suitable for evaluation in an animal disease model.
    • Metabolic stability optimization and metabolite identification of 2,5-thiophene amide 17β-hydroxysteroid dehydrogenase type 2 inhibitors.

      Gargano, Emanuele M; Perspicace, Enrico; Hanke, Nina; Carotti, Angelo; Marchais-Oberwinkler, Sandrine; Hartmann, Rolf W; Pharmaceutical and Medicinal Chemistry, Saarland University, Campus C2.3, D-66123 Saarbrücken, Germany. (2014-11-24)
      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.
    • Optimization of anti-virulence PqsR antagonists regarding aqueous solubility and biological properties resulting in new insights in structure-activity relationships.

      Lu, Cenbin; Kirsch, Benjamin; Maurer, Christine K; de Jong, Johannes C; Braunshausen, Andrea; Steinbach, Anke; Hartmann, Rolf W; Helmholtz-Institut für Pharmazeutische Forschung Saarland Campus, Geb. C2.3 Universität des Saarlandes, D-66123 Saarbrücken, Germany. (2014-05-22)
      Increasing antibiotic resistance urgently requires novel therapeutic options to combat bacterial infections. The anti-virulence therapy selectively intervening with pathogenicity without affecting bacterial viability is such a strategy to overcome resistance. We consider the virulence regulator PqsR as an attractive target in the human pathogen Pseudomonas aeruginosa, and recently discovered the first PqsR antagonists, which, however, suffered from poor aqueous solubility. In this work, the antagonists were structurally modified to become more soluble, and their structure-activity as well as structure-property relationships were studied. A novel promising compound with improved solubility and enhanced anti-virulence activity was discovered (IC50: 3.8 μM, pyocyanin). Our findings emphasize the crucial role of substituents at the 3-position and the carbonyl group at the 4-position for ligand-receptor interactions, and illuminate the way for further optimization of PqsR antagonists as anti-virulence agents.
    • Towards the evaluation in an animal disease model: Fluorinated 17β-HSD1 inhibitors showing strong activity towards both the human and the rat enzyme.

      Abdelsamie, Ahmed S; Bey, Emmanuel; Gargano, Emanuele M; van Koppen, Chris J; Empting, Martin; Frotscher, Martin; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus C23, D-66123 Saarbrücken, Germany. (2015-10-20)
      17β-Estradiol (E2), the most potent human estrogen, is known to be involved in the etiology of estrogen-dependent diseases (EDD) like breast cancer and endometriosis. 17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) catalyses the last step of E2 biosynthesis and is thus a promising target for the treatment of EDD. The previously described bicyclic substituted hydroxyphenylmethanones (BSHs) display high inhibitory potency towards human 17β-HSD1, but marginal activity towards rodent 17β-HSD1, precluding a proof of principle study in an animal endometriosis model. The aim of this work was to perform structural optimizations in the BSHs class to enhance inhibitory activity against rodent (mouse and rat) 17β-HSD1 while maintaining activity against the human enzyme. The introduction of fluorine atoms on the benzoyl moiety resulted in compounds with the desired properties. Molecular docking and homology modeling were applied to elucidate the binding mode and interspecies differences in activity. Compound 33 is the most potent inhibitor of both human and rat 17β-HSD1 up to date (IC50 = 2 nM and 97 nM, respectively).