• 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.
    • 17β-Hydroxysteroid Dehydrogenase Type 2 Inhibition: Discovery of Selective and Metabolically Stable Compounds Inhibiting Both the Human Enzyme and Its Murine Ortholog.

      Gargano, Emanuele M; Allegretta, Giuseppe; Perspicace, Enrico; Carotti, Angelo; Van Koppen, Chris; Frotscher, Martin; Marchais-Oberwinkler, Sandrine; Hartmann, Rolf W; Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS),Saarland 9 University, 66123 Saarbrücken, Germany. (2015)
      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.
    • 2-Aminothiazole Derivatives as Selective Allosteric Modulators of the Protein Kinase CK2. 2. Structure-Based Optimization and Investigation of Effects Specific to the Allosteric Mode of Action.

      Bestgen, Benoît; Kufareva, Irina; Seetoh, Weiguang; Abell, Chris; Hartmann, Rolf W; Abagyan, Ruben; Le Borgne, Marc; Filhol, Odile; Cochet, Claude; Lomberget, Thierry; et al. (American Chemical Society, 2019-02-28)
      Protein CK2 has gained much interest as an anticancer drug target in the past decade. We had previously described the identification of a new allosteric site on the catalytic α-subunit, along with first small molecule ligands based on the 4-(4-phenylthiazol-2-ylamino)benzoic acid scaffold. In the present work, structure optimizations guided by a binding model led to the identification of the lead compound 2-hydroxy-4-((4-(naphthalen-2-yl)thiazol-2-yl)amino)benzoic acid (27), showing a submicromolar potency against purified CK2α (IC
    • 3-Pyridyl substituted aliphatic cycles as CYP11B2 inhibitors: aromaticity abolishment of the core significantly increased selectivity over CYP1A2.

      Yin, Lina; Hu, Qingzhong; Hartmann, Rolf W; Pharmaceutical and Medicinal Chemistry, Saarland University & Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken, Germany. (2012)
      Aldosterone synthase (CYP11B2) is a promising therapeutic target for the treatment of cardiovascular diseases related to abnormally high aldosterone levels. On the basis of our previously identified lead compounds I-III, a series of 3-pyridinyl substituted aliphatic cycles were designed, synthesized and tested as CYP11B2 inhibitors. Aromaticity abolishment of the core was successfully applied to overcome the undesired CYP1A2 inhibition. This study resulted in a series of potent and selective CYP11B2 inhibitors, with compound 12 (IC(50) = 21 nM, SF = 50) as the most promising one, which shows no inhibition toward CYP1A2 at 2 µM. The design conception demonstrated in this study can be helpful in the optimization of CYP inhibitor drugs regarding CYP1A2 selectivity.
    • Absorption of Anthocyanin Rutinosides after Consumption of a Blackcurrant ( Ribes nigrum L.) Extract.

      Röhrig, Teresa; Kirsch, Verena; Schipp, Dorothea; Galan, Jens; Richling, Elke; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (American Chemical Society, 2019-06-19)
      The dominant anthocyanins in blackcurrant are delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside. Data on their absorption and distribution in the human body are limited. Therefore, we performed a human pilot study on five healthy male volunteers consuming a blackcurrant (Ribes nigrum L.) extract. The rutinosides and their degradation products gallic acid and protocatechuic acid were determined in plasma and urine. The rutinosides’ concentrations peaked in both plasma and urine samples within 2 h of extract ingestion. The recoveries of delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside from urine samples were 0.040 ± 0.011% and 0.048 ± 0.016%, respectively, over a 48 h period. Protocatechuic acid concentration increased significantly after ingestion of the blackcurrant extract. Our results show that after ingestion of a blackcurrant extract containing delphinidin-3-O-rutinoside and cyanidin-3-O-rutinoside, significant quantities of biologically active compounds circulated in the plasma and were excreted via urine. Furthermore, these results contribute to the understanding of anthocyanin metabolism in humans.
    • Advancing human pulmonary disease models in preclinical research: opportunities for lung-on-chips..

      Artzy-Schnirman, Arbel; Lehr, Claus-Michael; Sznitman, Josué; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Taylor&Francis, 2020-03-11)
      [No abstracr available]
    • An efficient synthesis of 1,6-anhydro- N -acetylmuramic acid from N -acetylglucosamine

      Calvert, Matthew B; Mayer, Christoph; Titz, Alexander; Helmholtz Institut für pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2017-12-11)
    • Anti-biofilm Agents against Pseudomonas aeruginosa: A Structure-Activity Relationship Study of C-Glycosidic LecB Inhibitors

      Sommer, Roman; Rox, Katharina; Wagner, Stefanie; Hauck, Dirk; Henrikus, Sarah S; Newsad, Shelby; Arnold, Tatjana; Ryckmans, Thomas; Brönstrup, Mark; Imberty, Anne; et al. (American Chemical Society, 2019-10-24)
      Biofilm formation is a key mechanism of antimicrobial resistance. We have recently reported two classes of orally bioavailable C-glycosidic inhibitors of the Pseudomonas aeruginosa lectin LecB with antibiofilm activity. They proved efficient in target binding, were metabolically stable, nontoxic, selective, and potent in inhibiting formation of bacterial biofilm. Here, we designed and synthesized six new carboxamides and 24 new sulfonamides for a detailed structure-activity relationship for two clinically representative LecB variants. Sulfonamides generally showed higher inhibition compared to carboxamides, which was rationalized based on crystal structure analyses. Substitutions at the thiophenesulfonamide increased binding through extensive contacts with a lipophilic protein patch. These metabolically stable compounds showed a further increase in potency toward the target and in biofilm inhibition assays. In general, we established the structure-activity relationship for these promising antibiofilm agents and showed that modification of the sulfonamide residue bears future optimization potential.
    • Aspherical and Spherical InvA497-Functionalized Nanocarriers for Intracellular Delivery of Anti-Infective Agents.

      Castoldi, Arianna; Empting, Martin; De Rossi, Chiara; Mayr, Karsten; Dersch, Petra; Hartmann, Rolf; Müller, Rolf; Gordon, Sarah; Lehr, Claus-Michael; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Springer, 2018-12-05)
      The objective of this work was to evaluate the potential of polymeric spherical and aspherical invasive nanocarriers, loaded with antibiotic, to access and treat intracellular bacterial infections. Aspherical nanocarriers were prepared by stretching of spherical precursors, and both aspherical and spherical nanocarriers were surface-functionalized with the invasive protein InvA497. The relative uptake of nanocarriers into HEp-2 epithelial cells was then assessed. Nanocarriers were subsequently loaded with a preparation of the non-permeable antibiotic gentamicin, and tested for their ability to treat HEp-2 cells infected with the enteroinvasive bacterium Shigella flexneri. InvA497-functionalized nanocarriers of both spherical and aspherical shape showed a significantly improved rate and extent of uptake into HEp-2 cells in comparison to non-functionalized nanocarriers. Functionalized and antibiotic-loaded nanocarriers demonstrated a dose dependent killing of intracellular S. flexneri. A slight but significant enhancement of intracellular bacterial killing was also observed with aspherical as compared to spherical functionalized nanocarriers at the highest tested concentration. InvA497-functionalized, polymer-based nanocarriers were able to efficiently deliver a non-permeable antibiotic across host cell membranes to affect killing of intracellular bacteria. Functionalized nanocarriers with an aspherical shape showed an interesting future potential for intracellular infection therapy.
    • 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.
    • Biophysical Screening of a Focused Library for the Discovery of CYP121 Inhibitors as Novel Antimycobacterials.

      Brengel, Christian; Thomann, Andreas; Schifrin, Alexander; Allegretta, Giuseppe; Kamal, Ahmed A M; Haupenthal, Jörg; Schnorr, Isabell; Cho, Sang Hyun; Franzblau, Scott G; Empting, Martin; et al. (2017-10-09)
      The development of novel antimycobacterial agents against Mycobacterium tuberculosis (Mtb) is urgently required due to the appearance of multidrug resistance (MDR) combined with complicated long-term treatment. CYP121 was shown to be a promising novel target for inhibition of mycobacterial growth. In this study, we describe the rational discovery of new CYP121 inhibitors by a systematic screening based on biophysical and microbiological methods. The best hits originating from only one structural class gave initial information about molecular motifs required for binding and activity. The initial screening procedure was followed by mode-of-action studies and further biological characterizations. The results demonstrate superior antimycobacterial efficacy and a decreased toxicity profile of our frontrunner compound relative to the reference compound econazole. Due to its low molecular weight, promising biological profile, and physicochemical properties, this compound is an excellent starting point for further rational optimization.
    • A Biophysical Study with Carbohydrate Derivatives Explains the Molecular Basis of Monosaccharide Selectivity of the Pseudomonas aeruginosa Lectin LecB.

      Sommer, Roman; Exner, Thomas E; Titz, Alexander; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Campus C 2.3, D-66123, Saarbrücken, Germany; Department of Chemistry and Graduate School Chemical Biology, University of Konstanz, D-78457, Konstanz, Germany. (2014)
      The rise of resistances against antibiotics in bacteria is a major threat for public health and demands the development of novel antibacterial therapies. Infections with Pseudomonas aeruginosa are a severe problem for hospitalized patients and for patients suffering from cystic fibrosis. These bacteria can form biofilms and thereby increase their resistance towards antibiotics. The bacterial lectin LecB was shown to be necessary for biofilm formation and the inhibition with its carbohydrate ligands resulted in reduced amounts of biofilm. The natural ligands for LecB are glycosides of d-mannose and l-fucose, the latter displaying an unusual strong affinity. Interestingly, although mannosides are much weaker ligands for LecB, they do form an additional hydrogen bond with the protein in the crystal structure. To analyze the individual contributions of the methyl group in fucosides and the hydroxymethyl group in mannosides to the binding, we designed and synthesized derivatives of these saccharides. We report glycomimetic inhibitors that dissect the individual interactions of their saccharide precursors with LecB and give insight into the biophysics of binding by LecB. Furthermore, theoretical calculations supported by experimental thermodynamic data suggest a perturbed hydrogen bonding network for mannose derivatives as molecular basis for the selectivity of LecB for fucosides. Knowledge gained on the mode of interaction of LecB with its ligands at ambient conditions will be useful for future drug design.
    • Biosynthesis of crocacin involves an unusual hydrolytic release domain showing similarity to condensation domains.

      Müller, Stefan; Rachid, Shwan; Hoffmann, Thomas; Surup, Frank; Volz, Carsten; Zaburannyi, Nestor; Müller, Rolf; Helmholtz Institute for Pharmaceutical Research Saarland,Saarbru¨ cken, Saarland 66123, Germany. (2014-07-17)
      The crocacins are potent antifungal and cytotoxic natural compounds from myxobacteria of the genus Chondromyces. Although total synthesis approaches have been reported, the molecular and biochemical basis guiding the formation of the linear crocacin scaffold has remained unknown. Along with the identification and functional analysis of the crocacin biosynthetic gene cluster from Chondromyces crocatus Cm c5, we here present the identification and biochemical characterization of an unusual chain termination domain homologous to condensation domains responsible for hydrolytic release of the product from the assembly line. In particular, gene inactivation studies and in vitro experiments using the heterologously produced domain CroK-C2 confirm this surprising role giving rise to the linear carboxylic acid. Additionally, we determined the kinetic parameters of CroK-C2 by monitoring hydrolytic cleavage of the substrate mimic N-acetylcysteaminyl-crocacin B using an innovative high-performance liquid chromatography mass spectrometry-based assay.
    • Caenorhabditis elegans N-glycan core beta-galactoside confers sensitivity towards nematotoxic fungal galectin CGL2.

      Butschi, Alex; Titz, Alexander; Wälti, Martin A; Olieric, Vincent; Paschinger, Katharina; Nöbauer, Katharina; Guo, Xiaoqiang; Seeberger, Peter H; Wilson, Iain B H; Aebi, Markus; et al. (2010-01)
      The physiological role of fungal galectins has remained elusive. Here, we show that feeding of a mushroom galectin, Coprinopsis cinerea CGL2, to Caenorhabditis elegans inhibited development and reproduction and ultimately resulted in killing of this nematode. The lack of toxicity of a carbohydrate-binding defective CGL2 variant and the resistance of a C. elegans mutant defective in GDP-fucose biosynthesis suggested that CGL2-mediated nematotoxicity depends on the interaction between the galectin and a fucose-containing glycoconjugate. A screen for CGL2-resistant worm mutants identified this glycoconjugate as a Galbeta1,4Fucalpha1,6 modification of C. elegans N-glycan cores. Analysis of N-glycan structures in wild type and CGL2-resistant nematodes confirmed this finding and allowed the identification of a novel putative glycosyltransferase required for the biosynthesis of this glycoepitope. The X-ray crystal structure of a complex between CGL2 and the Galbeta1,4Fucalpha1,6GlcNAc trisaccharide at 1.5 A resolution revealed the biophysical basis for this interaction. Our results suggest that fungal galectins play a role in the defense of fungi against predators by binding to specific glycoconjugates of these organisms.
    • 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.
    • Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis.

      Siebert, David C B; Sommer, Roman; Pogorevc, Domen; Hoffmann, Michael; Wenzel, Silke C; Müller, Rolf; Titz, Alexander; BRICS, Braunschweiger Zentrum für Systembiologie, Rebenring 56,38106 Braunschweig, Germany. (Beilstein Institut, 2019-01-01)
      The argyrins are secondary metabolites from myxobacteria with antibiotic activity against Pseudomonas aeruginosa. Studying their structure-activity relationship is hampered by the complexity of the chemical total synthesis. Mutasynthesis is a promising approach where simpler and fully synthetic intermediates of the natural product's biosynthesis can be biotechnologically incorporated. Here, we report the synthesis of a series of tripeptide thioesters as mutasynthons containing the native sequence with a dehydroalanine (Dha) Michael acceptor attached to a sarcosine (Sar) and derivatives. Chemical synthesis of the native sequence ᴅ-Ala-Dha-Sar thioester required revision of the sequential peptide synthesis into a convergent strategy where the thioester with sarcosine was formed before coupling to the Dha-containing dipeptide.
    • Cinnamide Derivatives of d -Mannose as Inhibitors of the Bacterial Virulence Factor LecB from Pseudomonas aeruginosa

      Sommer, Roman; Hauck, Dirk; Varrot, Annabelle; Wagner, Stefanie; Audfray, Aymeric; Prestel, Andreas; Möller, Heiko M.; Imberty, Anne; Titz, Alexander; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS);Saarland University, Building A4.1, 66123 Saarbruecken, Germany.; et al. (2015-12)
    • Ciprofloxacin-loaded lipid-core nanocapsules as mucus penetrating drug delivery system intended for the treatment of bacterial infections in cystic fibrosis.

      Torge, Afra; Wagner, Stefanie; Chaves, Paula S; Oliveira, Edilene G; Guterres, Silvia S; Pohlmann, Adriana R; Titz, Alexander; Schneider, Marc; Beck, Ruy C R; Helmholtz Institut für pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2017-05-10)
      Treatment of bacterial airway infections is essential for cystic fibrosis therapy. However, effectiveness of antibacterial treatment is limited as bacteria inside the mucus are protected from antibiotics and immune response. To overcome this biological barrier, ciprofloxacin was loaded into lipid-core nanocapsules (LNC) for high mucus permeability, sustained release and antibacterial activity. Ciprofloxacin-loaded LNC with a mean size of 180nm showed a by 50% increased drug permeation through mucus. In bacterial growth assays, the drug in the LNC had similar minimum inhibitory concentrations as the free drug in P. aeruginosa and S. aureus. Interestingly, formation of biofilm-like aggregates, which were observed for S. aureus treated with free ciprofloxacin, was avoided by exposure to LNC. With the combined advantages over the non-encapsulated drug, ciprofloxacin-loaded LNC represent a promising drug delivery system with the prospect of an improved antibiotic therapy in cystic fibrosis.
    • Comparing the Self-Assembly of Sexiphenyl-Dicarbonitrile on Graphite and Graphene on Cu(111).

      Schmidt, Nico; Li, Jun; Gottardi, Stefano; Moreno-Lopez, Juan Carlos; Enache, Mihaela; Monjas, Leticia; van der Vlag, Ramon; Havenith, Remco W A; Hirsch, Anna K H; Stöhr, Meike; et al. (Wiley-Blackwell, 2019-04-01)
      A comparative study on the self-assembly of sexiphenyl-dicarbonitrile on highly oriented pyrolytic graphite and single-layer graphene on Cu(111) is presented. Despite an overall low molecule-substrate interaction, the close-packed structures exhibit a peculiar shift repeating every four to five molecules. This shift has hitherto not been reported for similar systems and is hence a unique feature induced by the graphitic substrates.
    • Composing compound libraries for hit discovery--rationality-driven preselection or random choice by structural diversity?

      Weidel, Elisabeth; Negri, Matthias; Empting, Martin; Hinsberger, Stefan; Hartmann, Rolf W (2014)
      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.