• Structure-Activity Relationships of 2-Sufonylpyrimidines as Quorum-Sensing Inhibitors to Tackle Biofilm Formation and eDNA Release of Pseudomonas aeruginosa.

      Thomann, Andreas; Brengel, Christian; Börger, Carsten; Kail, Dagmar; Steinbach, Anke; Empting, Martin; Hartmann, Rolf W; Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS),Saarland Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2016-11-21)
      Drug-resistant Pseudomonas aeruginosa (PA) strains are on the rise, making treatment with current antibiotics ineffective. Hence, circumventing resistance or restoring the activity of antibiotics by novel approaches is of high demand. Targeting the Pseudomonas quinolone signal quorum sensing (PQS-QS) system is an intriguing strategy to abolish PA pathogenicity without affecting the viability of the pathogen. Herein we report the structure-activity relationships of 2-sulfonylpyrimidines, which were previously identified as dual-target inhibitors of the PQS receptor PqsR and the PQS synthase PqsD. The SAR elucidation was guided by a combined approach using ligand efficiency and ligand lipophilicity efficiency to select the most promising compounds. In addition, the most effective inhibitors were rationally modified by the guidance of QSAR using Hansch analyses. Finally, these inhibitors showed the capacity to decrease biofilm mass and extracellular DNA, which are important determinants for antibiotic resistance.
    • Structure-functionality relationship and pharmacological profiles of Pseudomonas aeruginosa alkylquinolone quorum sensing modulators.

      Kamal, Ahmed A M; Petrera, Lucia; Eberhard, Jens; Hartmann, Rolf W.; Helmholtz-Institu für pharmazeutische Forschung Saarland,, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2017-05-31)
      An important paradigm in anti-infective research is the antivirulence concept. Pathoblockers are compounds which disarm bacteria of their arsenal of virulence factors. PqsR is a transcriptional regulator controlling the production of such factors in Pseudomonas aeruginosa, most prominently pyocyanin. In this work, a series of tool compounds based on the structure of the natural ligand 2-heptyl-4-quinolone (HHQ) were used for probing the structure-functionality relationship. Four different profiles are identified namely agonists, antagonists, inverse agonists and biphasic modulators. Molecular docking studies revealed that each class of the PqsR modulators showed distinctive interactions in the PqsR binding domain. It was found that the substituents in position 3 of the quinolone core act as a switch between the different profiles, according to their ability to donate or accept a hydrogen bond, or form a hydrophobic interaction. Finally, it was shown that only inverse agonists were able to strongly inhibit pyocyanin production.
    • Submicron polymeric particles prepared by vibrational spray-drying: Semisolid formulation and skin penetration/permeation studies.

      Beber, T C; Andrade, D F; Kann, B; Fontana, M C; Coradini, K; Windbergs, M; Beck, R C R; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2014-11)
      Topical glucocorticoids (TG) such as dexamethasone (DEX) have been used for decades for the treatment of skin diseases. However, TG present well-documented side effects and their delivery to the skin is often insufficient. Therefore, many efforts have been undergone to improve the amount of drug delivered to the skin and to reduce side effects at the same time. In this work, the feasibility of DEX-submicron polymeric particles (SP) prepared by vibrational spray-drying as an approach to overcome the challenges associated with the topical administration of this drug class was evaluated. DEX was homogeneously dispersed in the SP matrix, according to confocal Raman microscopy analysis. Drug-loaded SP were incorporated into the oil phase of oil-in-water emulsions (creams). The formulation containing polymeric submicron particles (C-SP) showed controlled drug release kinetics and a significant drug accumulation in skin compared to formulations containing non-polymeric particles or free drug. DEX accumulation in the stratum corneum was evaluated by tape stripping and a depot effect over time was observed for C-SP, while the formulation containing the free drug showed a decrease over time. Similarly, C-SP presented higher drug retention in epidermis and dermis in skin penetration studies performed on pig skin in Franz diffusion cells, while drug permeation into the receptor compartment was negligible. It was demonstrated, for the first time, the advantageous application of submicron polymeric particles obtained by vibrational spray-drying in semisolid formulations for cutaneous administration to overcome challenges related to the therapy with TG such as DEX.
    • Surface state tunable energy and mass renormalization from homothetic quantum dot arrays.

      Piquero-Zulaica, Ignacio; Li, Jun; Abd El-Fattah, Zakaria M; Solianyk, Leonid; Gallardo, Iker; Monjas, Leticia; Hirsch, Anna K H; Arnau, Andres; Ortega, J Enrique; Stöhr, Meike; et al. (Royal Society of Chemistry, 2019-12-28)
      Quantum dot arrays in the form of molecular nanoporous networks are renowned for modifying the electronic surface properties through quantum confinement. Here we show that, compared to the pristine surface state, the band bottom of the confined states can exhibit downward shifts accompanied by a lowering of the effective masses simultaneous to the appearance of tiny gaps at the Brillouin zone boundaries. We observed these effects by angle resolved photoemission for two self-assembled homothetic (scalable) Co-coordinated metal-organic networks. Complementary scanning tunneling spectroscopy measurements confirmed these findings. Electron plane wave expansion simulations and density functional theory calculations provide insight into the nature of this phenomenon, which we assign to metal-organic overlayer-substrate interactions in the form of adatom-substrate hybridization. To date, the absence of the experimental band structure resulting from single metal adatom coordinated nanoporous networks has precluded the observation of the significant surface state renormalization reported here, which we infer to be general for low interacting and well-defined adatom arrays.
    • Synthesis and aromatase inhibitory activity of some new 16E-arylidenosteroids.

      Bansal, Ranju; Thota, Sridhar; Karkra, Nalin; Minu, Maninder; Zimmer, Christina; Hartmann, Rolf W; University Institute of Pharmaceutical Sciences, Sector-14, Panjab University, Chandigarh 160 014, India. ranju29in@yahoo.co.in (2012-12)
      A new series of 16E-arylidene androstene derivatives has been synthesized and evaluated for aromatase inhibitory activity. The impact of various aryl substituents at 16 position of the steroid skeleton on aromatase inhibitory activity has been observed. The 16E-arylidenosteroids 6, 10 and 11 exhibited significant inhibition of the aromatase enzyme. 16-(4-Pyridylmethylene)-4-androstene-3,17-dione (6, IC(50): 5.2 μM) and 16-(benzo-[1,3]dioxol-5-ylmethylene)androsta-1,4-diene-3,17-dione (11, IC(50): 6.4 μM) were found to be approximately five times more potent in comparison to aminoglutethimide.
    • Synthesis and Biological Evaluation of Novel 2-Substituted ­Analogues of (-)-Pentenomycin i

      Zisopoulou, Stavroula A.; Bousis, Spyridon; Haupenthal, Jörg; Herrmann, Jennifer; Müller, Rolf; Hirsch, Anna K.H.; Komiotis, Dimitri; Gallos, John K.; Stathakis, Christos I.; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Thieme, 2020-03-17)
      A library of novel 2-substituted derivatives of the antibiotic natural product pentenomycin I is presented. The new collection of analogues is divided in two main classes, 2-alkynyl- and 2-aryl- derivatives, which are accessed by the appropriate type of palladium-catalyzed cross-coupling reaction of the 2-iodo-protected pentenomycin I with suitable nucleophiles. The new derivatives were tested for their activity against certain types of bacteria and one of them, compound 8h, was found to exhibit significant inhibitory activity against several Gram-positive bacteria but also displayed cytotoxic activity against eukaryotic cell lines.
    • Synthesis and Biological Evaluation of Spiro-δ-lactones as Inhibitors of 17β-Hydroxysteroid Dehydrogenase Type 2 (17β-HSD2)

      Xu, Kuiying; Wetzel, Marie; W. Hartmann, Rolf; Marchais-Oberwinkler, Sandrine (2012-01-06)
    • Synthesis and biological evaluation of thieno[3,2-d]- pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones: conformationally restricted 17b-hydroxysteroid dehydrogenase type 2 (17b-HSD2) inhibitors.

      Perspicace, Enrico; Marchais-Oberwinkler, Sandrine; Hartmann, Rolf W; Pharmaceutical and Medicinal Chemistry, Saarland University, Campus C23, D-66123 Saarbrücken, Germany. (2013)
      In this study, a series of conformationally restricted thieno[3,2-d]pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones was designed and synthesized with the goal of improving the biological activity as 17b-hydroxysteroid dehydrogenase type 2 inhibitors of the corresponding amidothiophene derivatives. Two moderately active compounds were discovered and this allowed the identification of the biologically active open conformer as well as the extension of the enzyme binding site characterisation.
    • Synthetic studies of cystobactamids as antibiotics and bacterial imaging carriers lead to compounds with high: In vivo efficacy

      Testolin, Giambattista; Cirnski, Katarina; Rox, Katharina; Prochnow, Hans; Fetz, Verena; Grandclaudon, Charlotte; Mollner, Tim; Baiyoumy, Alain; Ritter, Antje; Leitner, Christian; et al. (RSC, 2020-01-01)
      There is an alarming scarcity of novel chemical matter with bioactivity against multidrug-resistant Gram-negative bacterial pathogens. Cystobactamids, recently discovered natural products from myxobacteria, are an exception to this trend. Their unusual chemical structure, composed of oligomeric para-aminobenzoic acid moieties, is associated with a high antibiotic activity through the inhibition of gyrase. In this study, structural determinants of cystobactamid's antibacterial potency were defined at five positions, which were varied using three different synthetic routes to the cystobactamid scaffold. The potency against Acinetobacter baumannii could be increased ten-fold to an MIC (minimum inhibitory concentration) of 0.06 μg mL−1, and the previously identified spectrum gap of Klebsiella pneumoniae could be closed compared to the natural products (MIC of 0.5 μg mL−1). Proteolytic degradation of cystobactamids by the resistance factor AlbD was prevented by an amide-triazole replacement. Conjugation of cystobactamid's N-terminal tetrapeptide to a Bodipy moiety induced the selective localization of the fluorophore for bacterial imaging purposes. Finally, a first in vivo proof of concept was obtained in an E. coli infection mouse model, where derivative 22 led to the reduction of bacterial loads (cfu, colony-forming units) in muscle, lung and kidneys by five orders of magnitude compared to vehicle-treated mice. These findings qualify cystobactamids as highly promising lead structures against infections caused by Gram-positive and Gram-negative bacterial pathogens.
    • 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).
    • Towards the sustainable discovery and development of new antibiotics.

      Miethke, Marcus; Pieroni, Marco; Weber, Tilmann; Brönstrup, Mark; Hammann, Peter; Halby, Ludovic; Arimondo, Paola B; Glaser, Philippe; Aigle, Bertrand; Bode, Helge B; et al. (Springer Nature, 2021-08-19)
      An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics. We propose both short-term and long-term solutions to overcome the most urgent limitations in the various sectors of research and funding, aiming to bridge the gap between academic, industrial and political stakeholders, and to unite interdisciplinary expertise in order to efficiently fuel the translational pipeline for the benefit of future generations.
    • Tracheal brush cells release acetylcholine in response to bitter tastants for paracrine and autocrine signaling.

      Hollenhorst, Monika I; Jurastow, Innokentij; Nandigama, Rajender; Appenzeller, Silke; Li, Lei; Vogel, Jörg; Wiederhold, Stephanie; Althaus, Mike; Empting, Martin; Altmüller, Janine; et al. (Wiley, 2020-01-01)
      For protection from inhaled pathogens many strategies have evolved in the airways such as mucociliary clearance and cough. We have previously shown that protective respiratory reflexes to locally released bacterial bitter "taste" substances are most probably initiated by tracheal brush cells (BC). Our single-cell RNA-seq analysis of murine BC revealed high expression levels of cholinergic and bitter taste signaling transcripts (Tas2r108, Gnat3, Trpm5). We directly demonstrate the secretion of acetylcholine (ACh) from BC upon stimulation with the Tas2R agonist denatonium. Inhibition of the taste transduction cascade abolished the increase in [Ca2+]i in BC and subsequent ACh-release. ACh-release is regulated in an autocrine manner. While the muscarinic ACh-receptors M3R and M1R are activating, M2R is inhibitory. Paracrine effects of ACh released in response to denatonium included increased [Ca2+]i in ciliated cells. Stimulation by denatonium or with Pseudomonas quinolone signaling molecules led to an increase in mucociliary clearance in explanted tracheae that was Trpm5- and M3R-mediated. We show that ACh-release from BC via the bitter taste cascade leads to immediate paracrine protective responses that can be boosted in an autocrine manner. This mechanism represents the initial step for the activation of innate immune responses against pathogens in the airways.
    • Unexpected results of a SNAr-reaction. A novel synthetic approach to 1-arylthio-2-naphthols

      Grombein, Cornelia M.; Hu, Qingzhong; Heim, Ralf; Huch, Volker; Hartmann, Rolf W.; Helmholtz-Institut für Pharmazeutische Forschung Saarland (2014-01-27)