Publications by authors named "Rolf W Hartmann"

246 Publications

Crystalline sponge affinity screening: A fast tool for soaking condition optimization without the need of X-ray diffraction analysis.

Eur J Pharm Sci 2021 Sep 20;164:105884. Epub 2021 Jun 20.

Discovery and Development Technologies (DDTech), Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany.

Structural elucidation of small molecules only available in low quantity (nanogram) is one of the big advantages of the crystalline sponge method. The optimization of various soaking parameters is crucial for effective analyte absorption and repetitive positioning in the pores of the crystal. Time-consuming X-ray diffraction measurements are necessary for data collection and confirmation of successful guest inclusion. In this work, we report a screening method to select optimal soaking conditions without the need of single-crystal X-ray diffraction analysis for individual compounds and mixtures. 14 substances were chosen as test compounds. Parallel guest soaking of individual compounds and mixtures was conducted using various soaking conditions. After evaporation of solvent, excessive material was removed, and guest molecules released through dissolution of the framework. Liquid chromatography-tandem mass spectrometry allowed the estimation of analyte trapped in the pores and the selection of optimal soaking condition dependent on the highest amount of analyte to crystal size (affinity factor). The tool allowed subsequent crystallographic analysis of ten compounds with minimal experiment time. Additionally, a study to examine the lower limit of detection of the crystalline sponge method was conducted. Determination of two target analytes was possible using only 5 ng of sample. Our study shows the potential of an affinity screening to prioritize soaking parameters by estimation of the guest concentration in a single crystal for one or multiple target compounds within a short period of time.
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http://dx.doi.org/10.1016/j.ejps.2021.105884DOI Listing
September 2021

Structure-Activity Relationship and Mode-of-Action Studies Highlight 1-(4-Biphenylylmethyl)-1H-imidazole-Derived Small Molecules as Potent CYP121 Inhibitors.

ChemMedChem 2021 May 19. Epub 2021 May 19.

Department for Drug Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland, Campus E8.1, 66123, Saarbrücken, Germany.

CYP121 of Mycobacterium tuberculosis (Mtb) is an essential target for the development of novel potent drugs against tuberculosis (TB). Besides known antifungal azoles, further compounds of the azole class were recently identified as CYP121 inhibitors with antimycobacterial activity. Herein, we report the screening of a similarity-oriented library based on the former hit compound, the evaluation of affinity toward CYP121, and activity against M. bovis BCG. The results enabled a comprehensive SAR study, which was extended through the synthesis of promising compounds and led to the identification of favorable features for affinity and/or activity and hit compounds with 2.7-fold improved potency. Mode of action studies show that the hit compounds inhibit substrate conversion and highlighted CYP121 as the main antimycobacterial target of our compounds. Exemplified complex crystal structures of CYP121 with three inhibitors reveal a common binding site. Engaging in both hydrophobic interactions as well as hydrogen bonding to the sixth iron ligand, our compounds block a solvent channel leading to the active site heme. Additionally, we report the first CYP inhibitors that are able to reduce the intracellular replication of M. bovis BCG in macrophages, emphasizing their potential as future drug candidates against TB.
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http://dx.doi.org/10.1002/cmdc.202100283DOI Listing
May 2021

From Celecoxib to a Novel Class of Phosphodiesterase 5 Inhibitors: Trisubstituted Pyrazolines as Novel Phosphodiesterase 5 Inhibitors with Extremely High Potency and Phosphodiesterase Isozyme Selectivity.

J Med Chem 2021 04 1;64(8):4462-4477. Epub 2021 Apr 1.

Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt.

A ligand-based approach involving systematic modifications of a trisubstituted pyrazoline scaffold derived from the COX2 inhibitor, celecoxib, was used to develop novel PDE5 inhibitors. Novel pyrazolines were identified with potent PDE5 inhibitory activity lacking COX2 inhibitory activity. Compound was the most potent with an IC of 1 nM, which was three times more potent than sildenafil and more selective with a selectivity index of >10,000-fold against all other PDE isozymes. Sildenafil inhibited the full-length and catalytic fragment of PDE5, while compound only inhibited the full-length enzyme, suggesting a mechanism of enzyme inhibition distinct from sildenafil. The PDE5 inhibitory activity of compound was confirmed in cells using a cGMP biosensor assay. Oral administration of compound achieved plasma levels >1000-fold higher than IC values and showed no discernable toxicity after repeated dosing. These results reveal a novel strategy to inhibit PDE5 with unprecedented potency and isozyme selectivity.
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http://dx.doi.org/10.1021/acs.jmedchem.0c01120DOI Listing
April 2021

Phosphonate as a Stable Zinc-Binding Group for "Pathoblocker" Inhibitors of Clostridial Collagenase H (ColH).

ChemMedChem 2021 Apr 16;16(8):1257-1267. Epub 2021 Mar 16.

Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Campus C2 3, 66123, Saarbrücken, Germany.

Microbial infections are a significant threat to public health, and resistance is on the rise, so new antibiotics with novel modes of action are urgently needed. The extracellular zinc metalloprotease collagenase H (ColH) from Clostridium histolyticum is a virulence factor that catalyses tissue damage, leading to improved host invasion and colonisation. Besides the major role of ColH in pathogenicity, its extracellular localisation makes it a highly attractive target for the development of new antivirulence agents. Previously, we had found that a highly selective and potent thiol prodrug (with a hydrolytically cleavable thiocarbamate unit) provided efficient ColH inhibition. We now report the synthesis and biological evaluation of a range of zinc-binding group (ZBG) variants of this thiol-derived inhibitor, with the mercapto unit being replaced by other zinc ligands. Among these, an analogue with a phosphonate motif as ZBG showed promising activity against ColH, an improved selectivity profile, and significantly higher stability than the thiol reference compound, thus making it an attractive candidate for future drug development.
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http://dx.doi.org/10.1002/cmdc.202000994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8251769PMC
April 2021

A hydrogel-based assay for the fast prediction of antibiotic accumulation in Gram-negative bacteria.

Mater Today Bio 2020 Sep 2;8:100084. Epub 2020 Nov 2.

Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany.

The pipeline of antibiotics has been for decades on an alarmingly low level. Considering the steadily emerging antibiotic resistance, novel tools are needed for early and easy identification of effective anti-infective compounds. In Gram-negative bacteria, the uptake of anti-infectives is especially limited. We here present a surprisingly simple model of the Gram-negative bacterial envelope, based on 20% (w/v) potato starch gel, printed on polycarbonate 96-well filter membranes. Rapid permeability measurements across this polysaccharide hydrogel allowed to correctly predict either high or low accumulation for all 16 tested anti-infectives in living . Freeze-fracture TEM supports that the macromolecular network structure of the starch hydrogel may represent a useful surrogate of the Gram-negative bacterial envelope. A random forest analysis of data revealed molecular mass, minimum projection area, and rigidity as the most critical physicochemical parameters for hydrogel permeability, in agreement with reported structural features needed for uptake into Gram-negative bacteria. Correlating our dataset of 27 antibiotics from different structural classes to reported MIC values of nine clinically relevant pathogens allowed to distinguish active from nonactive compounds based on their low permeability specifically for Gram-negatives. The model may help to identify poorly permeable antimicrobial candidates before testing them on living bacteria.
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http://dx.doi.org/10.1016/j.mtbio.2020.100084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7720078PMC
September 2020

Homology modeling meets site-directed mutagenesis: An ideal combination to elucidate the topology of 17β-HSD2.

J Steroid Biochem Mol Biol 2021 02 24;206:105790. Epub 2020 Nov 24.

Pharmaceutical Chemistry, Philipps University Marburg, Marbacher Weg 6, 35037 Marburg, Germany; Pharmaceutical and Medicinal Chemistry, Saarland University, Campus C2.3, 66123 Saarbrücken, Germany. Electronic address:

17β-Hydroxysteroid dehydrogenase type 2 (17β-HSD2) catalyzes the conversion of highly active estrogens and androgens into their less active forms using NAD as cofactor. Substrate and cofactor specificities of 17β-HSD2 have been reported and potent 17β-HSD2 inhibitors have been discovered in a ligand-based approach. However, the molecular basis and the amino acids involved in the enzymatic functionality are poorly understood, as no crystal structure of the membrane-associated 17β-HSD2 exists. The functional properties of only few amino acids are known. The lack of topological information impedes structure-based drug design studies and limits the design of biochemical experiments. The aim of this work was the determination of the 17β-HSD2 topology. For this, the first homology model of 17β-HSD2 in complex with NAD and 17β-estradiol was built, using a multi-fragment "patchwork" approach. To confirm the quality of the model, fifteen selected amino acids were exchanged one by one using site directed mutagenesis. The mutants' functional behavior demonstrated that the generated model was of very good quality and allowed the identification of several key amino acids involved in either ligand or internal structure stabilization. The final model is an optimal basis for further experiments like, for example, lead optimization.
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http://dx.doi.org/10.1016/j.jsbmb.2020.105790DOI Listing
February 2021

Discovery of trisubstituted pyrazolines as a novel scaffold for the development of selective phosphodiesterase 5 inhibitors.

Bioorg Chem 2020 11 28;104:104322. Epub 2020 Sep 28.

Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt. Electronic address:

Celecoxib, is a selective cyclooxygenase-2 (COX2) inhibitor with a 1,5-diaryl pyrazole scaffold. Celecoxib has a better safety profile compared to other COX2 inhibitors having side effects of systemic hypertension and thromboembolic complications. This may be partly attributed to an off-target activity involving phosphodiesterase 5 (PDE5) inhibition and the potentiation of NO/cGMP signalling allowing coronary vasodilation and aortic relaxation. Inspired by the structure of celecoxib, we synthesized a chemically diverse series of compounds containing a 1,3,5-trisubstituted pyrazoline scaffold to improve PDE5 inhibitory potency, while eliminating COX2 inhibitory activity. SAR studies for PDE5 inhibition revealed an essential role for a carboxylic acid functionality at the 1-phenyl and the importance of the non-planar pyrazoline core over the planar pyrazole with the 5-phenyl moiety tolerating a range of substituents. These modifications led to new PDE5 inhibitors with approximately 20-fold improved potency to inhibit PDE5 and no COX-2 inhibitory activity compared with celecoxib. PDE isozyme profiling of compound 11 revealed a favorable selectivity profile. These results suggest that trisubstituted pyrazolines provide a promising scaffold for further chemical optimization to identify novel PDE5 inhibitors with potential for less side effects compared with available PDE5 inhibitors used for the treatment of penile erectile dysfunction and pulmonary hypertension.
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http://dx.doi.org/10.1016/j.bioorg.2020.104322DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7686114PMC
November 2020

Micro-rheological properties of lung homogenates correlate with infection severity in a mouse model of Pseudomonas aeruginosa lung infection.

Sci Rep 2020 10 5;10(1):16502. Epub 2020 Oct 5.

Department of Drug Design and Optimization (DDOP), Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), Campus E8.1, 66123, Saarbrücken, Germany.

Lung infections caused by Pseudomonas aeruginosa pose a serious threat to patients suffering from, among others, cystic fibrosis, chronic obstructive pulmonary disease, or bronchiectasis, often leading to life-threatening complications. The establishment of a chronic infection is substantially related to communication between bacteria via quorum-sensing networks. In this study, we aimed to assess the role of quorum-sensing signaling molecules of the Pseudomonas quinolone signal (PQS) and to investigate the viscoelastic properties of lung tissue homogenates of PA-infected mice in a prolonged acute murine infection model. Therefore, a murine infection model was successfully established via intra-tracheal infection with alginate-supplemented Pseudomonas aeruginosa NH57388A. Rheological properties of lung homogenates were analyzed with multiple particle tracking (MPT) and quorum-sensing molecules were quantified with LC-MS/MS. Statistical analysis of bacterial load and quorum-sensing molecules showed a strong correlation between these biomarkers in infected lungs. This was accompanied by noticeable changes in the consistency of lung homogenates with increasing infection severity. Furthermore, viscoelastic properties of the lung homogenates strongly correlated with bacterial load and quorum sensing molecules. Considering the strong correlation between the viscoelasticity of lung homogenates and the aforementioned biomarkers, the viscoelastic properties of infected lungs might serve as reliable new biomarker for the evaluation of the severity of P. aeruginosa infections in murine models.
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http://dx.doi.org/10.1038/s41598-020-73459-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536435PMC
October 2020

Finding New Molecular Targets of Familiar Natural Products Using In Silico Target Prediction.

Int J Mol Sci 2020 Sep 26;21(19). Epub 2020 Sep 26.

Institute of Pharmacy, Department of Pharmaceutical and Medicinal Chemistry, Paracelsus Medical University Salzburg, Strubergasse 21, 5020 Salzburg, Austria.

Natural products comprise a rich reservoir for innovative drug leads and are a constant source of bioactive compounds. To find pharmacological targets for new or already known natural products using modern computer-aided methods is a current endeavor in drug discovery. Nature's treasures, however, could be used more effectively. Yet, reliable pipelines for the large-scale target prediction of natural products are still rare. We developed an in silico workflow consisting of four independent, stand-alone target prediction tools and evaluated its performance on dihydrochalcones (DHCs)-a well-known class of natural products. Thereby, we revealed four previously unreported protein targets for DHCs, namely 5-lipoxygenase, cyclooxygenase-1, 17β-hydroxysteroid dehydrogenase 3, and aldo-keto reductase 1C3. Moreover, we provide a thorough strategy on how to perform computational target predictions and guidance on using the respective tools.
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http://dx.doi.org/10.3390/ijms21197102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7582679PMC
September 2020

Evaluation of Bacterial RNA Polymerase Inhibitors in a -Based Wound Infection Model in SKH1 Mice.

ACS Infect Dis 2020 10 21;6(10):2573-2581. Epub 2020 Sep 21.

Institute of Medical Microbiology and Hygiene, Saarland University, 66421 Homburg, Saarland, Germany.

Chronic wounds infected with pathogens such as represent a worldwide health concern, especially in patients with a compromised immune system. As antimicrobial resistance has become an immense global problem, novel antibiotics are urgently needed. One strategy to overcome this threatening situation is the search for drugs targeting novel binding sites on essential and validated enzymes such as the bacterial RNA polymerase (RNAP). In this work, we describe the establishment of an wound infection model based on the pathogen and hairless Crl:SKH1-Hrhr (SKH1) mice. The model proved to be a valuable preclinical tool to study selected RNAP inhibitors after topical application. While rifampicin showed a reduction in the loss of body weight induced by the bacteria, an acceleration of wound healing kinetics, and a reduced number of colony forming units in the wound, the ureidothiophene-2-carboxylic acid was inactive under conditions, probably due to strong plasma protein binding. The cocrystal structure of compound with RNAP, that we hereby also present, will be of great value for applying appropriate structural modifications to further optimize the compound, especially in terms of plasma protein binding.
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http://dx.doi.org/10.1021/acsinfecdis.0c00034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7956220PMC
October 2020

Synthesis, Optimization, Antifungal Activity, Selectivity, and CYP51 Binding of New 2-Aryl-3-azolyl-1-indolyl-propan-2-ols.

Pharmaceuticals (Basel) 2020 Aug 8;13(8). Epub 2020 Aug 8.

EA1155-IICiMed, Institut de Recherche en Santé 2, Département de Pharmacochimie, Nantes Atlantique Universités, Université de Nantes, F-44200 Nantes, France.

A series of 2-aryl-3-azolyl-1-indolyl-propan-2-ols was designed as new analogs of fluconazole (FLC) by replacing one of its two triazole moieties by an indole scaffold. Two different chemical approaches were then developed. The first one, in seven steps, involved the synthesis of the key intermediate 1-(1-benzotriazol-1-yl)methyl-1-indole and the final opening of oxiranes by imidazole or 1-1,2,4-triazole. The second route allowed access to the target compounds in only three steps, this time with the ring opening by indole and analogs. Twenty azole derivatives were tested against and other species. The enantiomers of the best anti- compound, 2-(2,4-dichlorophenyl)-3-(1-indol-1-yl)-1-(1-1,2,4-triazol-1-yl)-propan-2-ol (), were analyzed by X-ray diffraction to determine their absolute configuration. The (-)- enantiomer (Minimum inhibitory concentration (MIC) = IC = 0.000256 µg/mL on CA98001) was found with the -absolute configuration. In contrast the ()- enantiomer was found with the -absolute configuration (MIC = 0.023 µg/mL on CA98001). By comparison, the MIC value for FLC was determined as 0.020 µg/mL for the same clinical isolate. Additionally, molecular docking calculations and molecular dynamics simulations were carried out using a crystal structure of lanosterol 14α-demethylase (CaCYP51). The (-)-()- enantiomer aligned with the positioning of posaconazole within both the heme and access channel binding sites, which was consistent with its biological results. All target compounds have been also studied against human fetal lung fibroblast (MRC-5) cells. Finally, the selectivity of four compounds on a panel of human P450-dependent enzymes (CYP19, CYP17, CYP26A1, CYP11B1, and CYP11B2) was investigated.
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http://dx.doi.org/10.3390/ph13080186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7464559PMC
August 2020

-Aryl-3-mercaptosuccinimides as Antivirulence Agents Targeting Elastase and Collagenases.

J Med Chem 2020 08 17;63(15):8359-8368. Epub 2020 Jun 17.

Department of Drug Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), Campus Building E8.1, 66123 Saarbrücken, Germany.

In light of the global antimicrobial-resistance crisis, there is an urgent need for novel bacterial targets and antibiotics with novel modes of action. It has been shown that elastase (LasB) and () collagenase (ColH) play a significant role in the infection process and thereby represent promising antivirulence targets. Here, we report novel -aryl-3-mercaptosuccinimide inhibitors that target both LasB and ColH, displaying potent activities and high selectivity for the bacterial over human metalloproteases. Additionally, the inhibitors demonstrate no signs of cytotoxicity against selected human cell lines and in a zebrafish embryo toxicity model. Furthermore, the most active ColH inhibitor shows a significant reduction of collagen degradation in an pig-skin model.
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http://dx.doi.org/10.1021/acs.jmedchem.0c00584DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7429951PMC
August 2020

Crystalline Sponges as a Sensitive and Fast Method for Metabolite Identification: Application to Gemfibrozil and its Phase I and II Metabolites.

Drug Metab Dispos 2020 07 20;48(7):587-593. Epub 2020 May 20.

Discovery and Development Technologies (DDTech) (L.R., K.U., K.G., L.B.) and Innovation Center (C.v.E., A.K., C.K.), Merck KGaA, Darmstadt, Germany; and Department of Drug Design and Optimization (DDOP), Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS)-Helmholtz Centre for Infection Research (HZI), Saarbrücken, Germany (L.R., R.W.H.)

Understanding the metabolism of new drug candidates is important during drug discovery and development, as circulating metabolites may contribute to efficacy or cause safety issues. In the early phase of drug discovery, human in vitro systems are used to investigate human relevant metabolism. Though conventional techniques are limited in their ability to provide complete molecular structures of metabolites (liquid chromatography mass spectrometry) or require a larger amount of material not available from in vitro incubation (nuclear magnetic resonance), we here report for the first time the use of the crystalline sponge method to identify phase I and phase II metabolites generated from in vitro liver microsomes or S9 fractions. Gemfibrozil was used as a test compound. Metabolites generated from incubation with microsomes or S9 fractions, were fractionated using online fraction collection. After chromatographic purification and fractionation of the generated metabolites, single crystal X-ray diffraction of crystalline sponges was used to identify the structure of gemfibrozil metabolites. This technique allowed for complete structure elucidation of 5'-CHOH gemfibrozil (M1), 4'-OH gemfibrozil (M2), 5'-COOH gemfibrozil (M3), and the acyl glucuronide of gemfibrozil, 1-O--glucuronide (M4), the first acyl glucuronide available in the Cambridge Crystallographic Data Centre. Our study shows that when optimal soaking is possible, crystalline sponges technology is a sensitive (nanogram amount) and fast (few days) method that can be applied early in drug discovery to identify the structure of pure metabolites from in vitro incubations. SIGNIFICANCE STATEMENT: Complete structure elucidation of human metabolites plays a critical role in early drug discovery. Low amounts of material (nanogram) are only available at this stage and insufficient for nuclear magnetic resonance analysis. The crystalline sponge method has the potential to close this gap, as demonstrated in this study.
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http://dx.doi.org/10.1124/dmd.120.091140DOI Listing
July 2020

Squalenyl Hydrogen Sulfate Nanoparticles for Simultaneous Delivery of Tobramycin and an Alkylquinolone Quorum Sensing Inhibitor Enable the Eradication of P. aeruginosa Biofilm Infections.

Angew Chem Int Ed Engl 2020 06 11;59(26):10292-10296. Epub 2020 May 11.

Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Center for Infection Research, 66123, Saarbrücken, Germany.

Elimination of pulmonary Pseudomonas aeruginosa (PA) infections is challenging to accomplish with antibiotic therapies, mainly due to resistance mechanisms. Quorum sensing inhibitors (QSIs) interfering with biofilm formation can thus complement antibiotics. For simultaneous and improved delivery of both active agents to the infection sites, self-assembling nanoparticles of a newly synthesized squalenyl hydrogen sulfate (SqNPs) were prepared. These nanocarriers allowed for remarkably high loading capacities of hydrophilic antibiotic tobramycin (Tob) and a novel lipophilic QSI at 30 % and circa 10 %, respectively. The drug-loaded SqNPs showed improved biofilm penetration and enhanced efficacy in relevant biological barriers (mucin/human tracheal mucus, biofilm), leading to complete eradication of PA biofilms at circa 16-fold lower Tob concentration than Tob alone. This study offers a viable therapy optimization and invigorates the research and development of QSIs for clinical use.
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http://dx.doi.org/10.1002/anie.202001407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317969PMC
June 2020

Cystobactamid 507: Concise Synthesis, Mode of Action, and Optimization toward More Potent Antibiotics.

Chemistry 2020 Jun 28;26(32):7219-7225. Epub 2020 Apr 28.

Department of Drug Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland, Saarland University, Campus E8.1, 66123, Saarbrücken, Germany.

Lack of new antibiotics and increasing antimicrobial resistance are among the main concerns of healthcare communities nowadays, and these concerns necessitate the search for novel antibacterial agents. Recently, we discovered the cystobactamids-a novel natural class of antibiotics with broad-spectrum antibacterial activity. In this work, we describe 1) a concise total synthesis of cystobactamid 507, 2) the identification of the bioactive conformation using noncovalently bonded rigid analogues, and 3) the first structure-activity relationship (SAR) study for cystobactamid 507 leading to new analogues with high metabolic stability, superior topoisomerase IIA inhibition, antibacterial activity and, importantly, stability toward the resistant factor AlbD. Deeper insight into the mode of action revealed that the cystobactamids employ DNA minor-groove binding as part of the drug-target interaction without showing significant intercalation. By designing a new analogue of cystobactamid 919-2, we finally demonstrated that these findings could be further exploited to obtain more potent hexapeptides against Gram-negative bacteria.
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http://dx.doi.org/10.1002/chem.202000117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317206PMC
June 2020

Semisynthesis and biological evaluation of amidochelocardin derivatives as broad-spectrum antibiotics.

Eur J Med Chem 2020 Feb 20;188:112005. Epub 2019 Dec 20.

Department of Chemical Biology, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124, Braunschweig, Germany; German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124, Braunschweig, Germany. Electronic address:

To address the global challenge of emerging antimicrobial resistance, the hitherto most successful strategy to new antibiotics has been the optimization of validated natural products; most of these efforts rely on semisynthesis. Herein, we report the semisynthetic modification of amidochelocardin, an atypical tetracycline obtained via genetic engineering of the chelocardin producer strain. We report modifications at C4, C7, C10 and C11 by the application of methylation, acylation, electrophilic substitution, and oxidative C-C coupling reactions. The antibacterial activity of the reaction products was tested against a panel of Gram-positive and Gram-negative pathogens. The emerging structure-activity relationships (SARs) revealed that positions C7 and C10 are favorable anchor points for the semisynthesis of optimized derivatives. The observed SAR was different from that known for tetracyclines, which underlines the pronounced differences between the two compound classes.
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http://dx.doi.org/10.1016/j.ejmech.2019.112005DOI Listing
February 2020

Profiling of anabolic androgenic steroids and selective androgen receptor modulators for interference with adrenal steroidogenesis.

Biochem Pharmacol 2020 02 27;172:113781. Epub 2019 Dec 27.

Swiss Centre for Applied Human Toxicology (SCAHT), University of Basel, Basel, Switzerland; Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland. Electronic address:

Anabolic-androgenic steroids (AAS) are testosterone derivatives developed for steroid-replacement and treatment of debilitating conditions. They are widely used by athletes in elite sports and bodybuilding due to their muscle-building and performance-enhancing properties. Excessive AAS use is associated with cardiovascular diseases, mood changes, endocrine and metabolic disorders; however, the underlying mechanisms remain unknown. Selective androgen receptor modulators (SARMs) aim to reduce adverse androgenic effects, while maximizing anabolic effects. This study assessed potential steroidogenic disturbances of 19 AAS and 3 SARMs in human adrenocortical carcinoma H295R cells, comparing basal and forskolin-activated states by mass spectrometry-based quantification of nine major adrenal steroids. Mesterolone, mestanolone and methenolone increased mineralocorticoid but decreased adrenal androgen production, indicating CYP17A1 dysfunction. Cell-free activity assays failed to detect direct CYP17A1 inhibition, supported by molecular modeling. The mRNA expression levels of 3β-HSD2, CYP17A1, CYP21A2, CYP11B1 and CYP11B2 were unaffected, suggesting indirect inhibition involving post-translational modification and/or impaired protein stability. Clostebol and oxymetholone decreased corticosteroid but increased dehydroepiandrosterone biosynthesis in H295R cells, suggesting CYP21A2 inhibition, sustained by molecular modeling. These AAS did not affect the expression of key steroidogenic genes. None of the SARMs tested interfered with steroidogenesis. The chosen approach allowed the grouping of AAS according to their steroidogenic-disrupting effects and provided initial mechanistic information. Mesterolone, mestanolone and methenolone potentially promote hypertension and cardiovascular diseases via excessive mineralocorticoid biosynthesis. Clostebol and oxymetholone might cause metabolic disturbances by suppressing corticosteroid production, resulting in adrenal hyperplasia. The non-steroidal SARMs exhibit an improved safety profile and represent a preferred therapeutic option.
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http://dx.doi.org/10.1016/j.bcp.2019.113781DOI Listing
February 2020

Synthetic studies of cystobactamids as antibiotics and bacterial imaging carriers lead to compounds with high efficacy.

Chem Sci 2019 Dec 10;11(5):1316-1334. Epub 2019 Dec 10.

Department of Chemical Biology, Helmholtz Centre for Infection Research Inhoffenstrasse 7 38124 Braunschweig Germany

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 -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 could be increased ten-fold to an MIC (minimum inhibitory concentration) of 0.06 μg mL, and the previously identified spectrum gap of could be closed compared to the natural products (MIC of 0.5 μg mL). 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 proof of concept was obtained in an infection mouse model, where derivative 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.
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http://dx.doi.org/10.1039/c9sc04769gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8148378PMC
December 2019

Anti-biofilm Agents against : A Structure-Activity Relationship Study of -Glycosidic LecB Inhibitors.

J Med Chem 2019 10 11;62(20):9201-9216. Epub 2019 Oct 11.

Chemical Biology of Carbohydrates , Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research , D-66123 Saarbrücken , Germany.

Biofilm formation is a key mechanism of antimicrobial resistance. We have recently reported two classes of orally bioavailable -glycosidic inhibitors of the 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.
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http://dx.doi.org/10.1021/acs.jmedchem.9b01120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6873108PMC
October 2019

Design, Synthesis, and Biological Characterization of Orally Active 17β-Hydroxysteroid Dehydrogenase Type 2 Inhibitors Targeting the Prevention of Osteoporosis.

J Med Chem 2019 08 25;62(15):7289-7301. Epub 2019 Jul 25.

Department of Pharmaceutical and Medicinal Chemistry , Saarland University , 66123 Saarbrücken , Germany.

Osteoporosis is predominantly treated with drugs that inhibit further bone resorption due to estrogen deficiency. Yet, osteoporosis drugs that not only inhibit bone resorption but also stimulate bone formation, such as potentially inhibitors of 17β-hydroxysteroid dehydrogenase type 2 (17β-HSD2), may be more efficacious in the treatment of osteoporosis. Blockade of 17β-HSD2 is thought to increase intracellular estradiol and testosterone in bone, thereby inhibiting bone resorption by osteoclasts and stimulating bone formation by osteoblasts, respectively. We here describe the design, synthesis, and biological characterization of a novel bicyclic-substituted hydroxyphenylmethanone 17β-HSD2 inhibitor (compound ). Compound is a nanomolar potent inhibitor of human 17β-HSD2 (IC of 6.1 nM) and rodent 17β-HSD2 with low in vitro cellular toxicity, devoid of detectable estrogen receptor α affinity, displays high aqueous solubility and in vitro metabolic stability, and has an excellent oral pharmacokinetic profile for testing in a rat osteoporosis model. Administration of in a rat osteoporosis model demonstrates its bone-sparing efficacy.
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http://dx.doi.org/10.1021/acs.jmedchem.9b00932DOI Listing
August 2019

Effects of 17β-HSD2 inhibition in bones on osteoporosis based on an animal rat model.

J Steroid Biochem Mol Biol 2019 09 8;192:105405. Epub 2019 Jun 8.

Technische Universität Dresden, Molecular Cell Physiology and Endocrinology, Institute for Zoology, Dresden, Germany. Electronic address:

Hormone replacement therapy is a viable option to protect bone from postmenopausal osteoporosis. Systemically elevated estrogen levels, however, are disadvantageous because of the risk of harmful side effects in other organs. The rationale of the study presented here is to target a key enzyme in estradiol (E2) and testosterone (T) metabolism to increase E2 levels in an organ-specific manner, thereby avoiding the disadvantages of systemically increased E2 levels. The 17ß-hydroxysteroid dehydrogenase (17β-HSD2), which is e.g. expressed in bone, catalyzes the oxidation of E2 and T into estrone (E1) and androstenedione. We postulate that inhibiting 17β-HSD2 should lead to elevated E2 and T levels in organs expressing the enzyme. Therefore, we can use the benefits of E2 directly, or those of T following aromatization into E2, in the bone without affecting systemic levels. We tested for the first time, the novel and potent 17β-HSD2 inhibitor, compound 24 (C24), to explore the therapeutic potential of a 17β-HSD2 inhibition in an ovariectomy (ovx)-induced rat model of bone loss. We tested the inhibitor alone and, together with low dose estrogen supplementation to model estrogen levels in the postmenopausal situation. Female mature Wistar-Hannover rats were treated for 8 weeks with doses of 2, 10, 50 mg C24 per kg body weight per day alone or in the presence of estradiol benzoate (E2B) supplementation to alleviate ovx-induced bone loss. Ovx placebo and sham operated animals served as negative and positive controls. The experiment was evaluated regarding aspects of efficacy and safety: Bone was analyzed to evaluate bone protective effects, and uterus for potential, unwanted E2-mediated side effects. We observed a good bioavailability of C24 as very high plasma concentrations were measured, up to a group mean of 15,412 nM for the ovx C24-high group. Histomorphometrical analyses and in vivo &ex vivo μCT revealed significant bone protective effects for the lowest inhibitor concentration used. Irrespective of the plasma concentration, no proliferative effects in the uterus could be observed. These results support our approach of intracellular targeting key enzymes of E2 and T metabolism to increase E2 and T levels in an organ specific manner.
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http://dx.doi.org/10.1016/j.jsbmb.2019.105405DOI Listing
September 2019

Development of potential preclinical candidates with promising in vitro ADME profile for the inhibition of type 1 and type 2 17β-Hydroxysteroid dehydrogenases: Design, synthesis, and biological evaluation.

Eur J Med Chem 2019 Sep 31;178:93-107. Epub 2019 May 31.

Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), Department of Drug Design and Optimization, Campus Building E8.1, 66123, Saarbrücken, Germany; Department of Pharmaceutical and Medicinal Chemistry, Saarland University, 66123, Saarbrücken, Germany.

Estrogens are the major female sex steroid hormones, estradiol (E2) being the most potent form in humans. Disturbing the balance between E2 and its weakly active oxidized form estrone (E1) leads to diverse types of estrogen-dependent diseases such as endometriosis or osteoporosis. 17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) catalyzes the biosynthesis of E2 by reduction of E1 while the type 2 enzyme catalyzes the reverse reaction. Thus, 17β-HSD1 and 17β-HSD2 are attractive targets for treatment of estrogen-dependent diseases. Recently, we reported the first proof-of-principle study of a 17β-HSD2 inhibitor in a bone fracture mouse model, using subcutaneous administration. In the present study, our aim was to improve the in vitro ADME profile of the most potent 17β-HSD1 and 17β-HSD2 inhibitors described so far. The optimized compounds show strong and selective inhibition of both the human enzymes and their murine orthologs. In addition, they display good metabolic stability in human liver microsomes (S9 fraction), low in vitro cytotoxicity as well as better aqueous solubility and physicochemical properties compared to the lead compounds. These achievements make the compounds eligible for testing in preclinical in vivo animal model studies on the effects of inhibition of 17β-HSD1 and 17β-HSD2.
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http://dx.doi.org/10.1016/j.ejmech.2019.05.084DOI Listing
September 2019

Identification of the fungicide epoxiconazole by virtual screening and biological assessment as inhibitor of human 11β-hydroxylase and aldosterone synthase.

J Steroid Biochem Mol Biol 2019 09 6;192:105358. Epub 2019 Apr 6.

Institute of Pharmacy / Pharmaceutical Chemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria; Department of Medicinal and Pharmaceutical Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 22, 5020, Salzburg, Austria. Electronic address:

Humans are constantly exposed to a multitude of environmental chemicals that may disturb endocrine functions. It is crucial to identify such chemicals and uncover their mode-of-action to avoid adverse health effects. 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) catalyze the formation of cortisol and aldosterone, respectively, in the adrenal cortex. Disruption of their synthesis by exogenous chemicals can contribute to cardio-metabolic diseases, chronic kidney disease, osteoporosis, and immune-related disorders. This study applied in silico screening and in vitro evaluation for the discovery of xenobiotics inhibiting CYP11B1 and CYP11B2. Several databases comprising environmentally relevant pollutants, chemicals in body care products, food additives and drugs were virtually screened using CYP11B1 and CYP11B2 pharmacophore models. A first round of biological testing used hamster cells overexpressing human CYP11B1 or CYP11B2 to analyze 25 selected virtual hits. Three compounds inhibited CYP11B1 and CYP11B2 with IC values below 3 μM. The most potent inhibitor was epoxiconazole (IC value of 623 nM for CYP11B1 and 113 nM for CYP11B2, respectively); flurprimidol and ancymidol were moderate inhibitors. In a second round, these three compounds were tested in human adrenal H295R cells endogenously expressing CYP11B1 and CYP11B2, confirming the potent inhibition by epoxiconazole and the more moderate effects by flurprimidol and ancymidol. Thus, the in silico screening, prioritization of chemicals for initial biological tests and use of H295R cells to provide initial mechanistic information is a promising strategy to identify potential endocrine disruptors inhibiting corticosteroid synthesis. A critical assessment of human exposure levels and in vivo evaluation of potential corticosteroid disrupting effects by epoxiconazole is required.
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http://dx.doi.org/10.1016/j.jsbmb.2019.04.007DOI Listing
September 2019

Benzophenones as xanthone-open model CYP11B1 inhibitors potentially useful for promoting wound healing.

Bioorg Chem 2019 05 30;86:401-409. Epub 2019 Jan 30.

Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Via Belmeloro, 6, I-40126 Bologna, Italy. Electronic address:

The inhibition of steroidogenic cytochrome P450 enzymes has been shown to play a central role in the management of life-threatening diseases such as cancer, and indeed potent inhibitors of CYP19 (aromatase) and CYP17 (17α hydroxylase/17,20 lyase) are currently used for the treatment of breast, ovarian and prostate cancer. In the last few decades CYP11B1 (11-β-hydroxylase) and CYP11B2 (aldosterone synthase), key enzymes in the biosynthesis of cortisol and aldosterone, respectively, have been also investigated as targets for the identification of new potent and selective agents for the treatment of Cushing's syndrome, impaired wound healing and cardiovascular diseases. In an effort to improve activity and synthetic feasibility of our different series of xanthone-based CYP11B1 and CYP11B2 inhibitors, a small series of imidazolylmethylbenzophenone-based compounds, previously reported as CYP19 inhibitors, was also tested on these new targets, in order to explore the role of a more flexible scaffold for the inhibition of CYP11B1 and -B2 isoforms. Compound 3 proved to be very potent and selective towards CYP11B1, and was thus selected for further optimization via appropriate decoration of the scaffold, leading to new potent 4'-substituted derivatives. In this second series, 4 and 8, carrying a methoxy group and a phenyl ring, respectively, proved to be low-nanomolar inhibitors of CYP11B1, despite a slight decrease in selectivity against CYP11B2. Moreover, unlike the benzophenones of the first series, the 4'-substituted derivatives also proved to be selective for CYP11B enzymes, showing very weak inhibition of CYP19 and CYP17. Notably, the promising result of a preliminary scratch test performed on compound 8 confirmed the potential of this compound as a wound-healing promoter.
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http://dx.doi.org/10.1016/j.bioorg.2019.01.066DOI Listing
May 2019

2-Aminothiazole Derivatives as Selective Allosteric Modulators of the Protein Kinase CK2. 1. Identification of an Allosteric Binding Site.

J Med Chem 2019 02 18;62(4):1803-1816. Epub 2019 Feb 18.

Université de Lyon, Université Lyon 1, Faculté de Pharmacie, ISPB, EA 4446 Bioactive Molecules and Medicinal Chemistry, SFR Santé Lyon-Est CNRS UMS3453, INSERM US7, F-69373 , Lyon Cedex 08, France.

CK2 is a ubiquitous Ser/Thr protein kinase involved in the control of various signaling pathways and is known to be constitutively active. In the present study, we identified aryl 2-aminothiazoles as a novel class of CK2 inhibitors, which displayed a non-ATP-competitive mode of action and stabilized an inactive conformation of CK2 in solution. Enzyme kinetics studies, STD NMR, circular dichroism spectroscopy, and native mass spectrometry experiments demonstrated that the compounds bind in an allosteric pocket outside the ATP-binding site. Our data, combined with molecular docking studies, strongly suggested that this new binding site was located at the interface between the αC helix and the flexible glycine-rich loop. A first hit optimization led to compound 7, exhibiting an IC of 3.4 μM against purified CK2α in combination with a favorable selectivity profile. Thus, we identified a novel class of CK2 inhibitors targeting an allosteric pocket, offering great potential for further optimization into anticancer drugs.
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http://dx.doi.org/10.1021/acs.jmedchem.8b01766DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7667462PMC
February 2019

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.

J Med Chem 2019 02 13;62(4):1817-1836. Epub 2019 Feb 13.

Pharmaceutical and Medicinal Chemistry , Saarland University , Campus C2.3, 66123 Saarbrücken , Germany.

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 = 0.6 μM). Furthermore, 27 induced apoptosis and cell death in 786-O renal cell carcinoma cells (EC = 5 μM) and inhibited STAT3 activation even more potently than the ATP-competitive drug candidate CX-4945 (EC of 1.6 μM vs 5.3 μM). Notably, the potencies of our allosteric ligands to inhibit CK2 varied depending on the individual substrate. Altogether, the novel allosteric pocket was proved a druggable site, offering an excellent perspective to develop efficient and selective allosteric CK2 inhibitors.
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http://dx.doi.org/10.1021/acs.jmedchem.8b01765DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7579840PMC
February 2019

Targeted Endocrine Therapy: Design, Synthesis, and Proof-of-Principle of 17β-Hydroxysteroid Dehydrogenase Type 2 Inhibitors in Bone Fracture Healing.

J Med Chem 2019 02 15;62(3):1362-1372. Epub 2019 Jan 15.

ElexoPharm GmbH , Im Stadtwald, Building A1.2 , 66123 Saarbrücken , Germany.

Current therapies of steroid hormone-dependent diseases predominantly alter steroid hormone concentrations (or their actions) in plasma, in target and nontarget tissues alike, rather than in target organs only. Targeted therapy through the inhibition of steroidogenic enzymes may pose an attractive alternative with much less side effects. Here, we describe the design of a nanomolar potent 17β-hydroxysteroid dehydrogenase type 2 (17β-HSD2) inhibitor (compound 15) and successful targeted intracrine therapy in a mouse bone fracture model. Blockade of 17β-HSD2 in bone is thought to increase intracellular estradiol (E2) and testosterone (T), which thereby inhibits bone resorption by osteoclasts and stimulates bone formation by osteoblasts, respectively. Administration of compound 15 in the mouse fracture model strongly increases the mechanical stability of the healing fractured bone because of a larger periosteal callus with newly formed bone without changing the plasma E2 and T concentrations. Steroidogenic 17β-HSD2 inhibition thus enables targeted intracrine therapy.
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http://dx.doi.org/10.1021/acs.jmedchem.8b01493DOI Listing
February 2019

Highly Potent 17β-HSD2 Inhibitors with a Promising Pharmacokinetic Profile for Targeted Osteoporosis Therapy.

J Med Chem 2018 12 27;61(23):10724-10738. Epub 2018 Nov 27.

Department of Pharmacy , Saarland University , Campus C2.3 , 66123 Saarbrücken , Germany.

Intracellular elevation of E2 levels in bone by inhibition of 17β hydroxysteroid dehydrogenase type 2 (17β-HSD2) without affecting systemic E2 levels is an attractive approach for a targeted therapy against osteoporosis, a disease which is characterized by loss of bone mineral density. Previously identified inhibitor A shows high potency on human and mouse 17β-HSD2, but poor pharmacokinetic properties when applied perorally in mice. A combinatorial chemistry approach was utilized to synthesize truncated derivatives of A, leading to highly potent compounds with activities in the low nanomolar to picomolar range. Compound 33, comparable to A in terms of inhibitor potency against both human and mouse enzymes, displays high in vitro metabolic stability in human and mouse liver S9 fraction as well as low toxicity and moderate hepatic CYP inhibition. Thus, compound 33 showed a highly improved peroral pharmacokinetic profile in comparison to A, making 33 a promising candidate for further development.
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http://dx.doi.org/10.1021/acs.jmedchem.8b01373DOI Listing
December 2018

Tackling Pseudomonas aeruginosa Virulence by a Hydroxamic Acid-Based LasB Inhibitor.

ACS Chem Biol 2018 09 24;13(9):2449-2455. Epub 2018 Aug 24.

Department of Drug Design and Optimization , Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) , Campus E8.1 , 66123 Saarbrücken , Germany.

In search of novel antibiotics to combat the challenging spread of resistant pathogens, bacterial proteases represent promising targets for pathoblocker development. A common motif for protease inhibitors is the hydroxamic acid function, yet this group has often been related to unspecific inhibition of various metalloproteases. In this work, the inhibition of LasB, a harmful zinc metalloprotease secreted by Pseudomonas aeruginosa, through a hydroxamate derivative is described. The present inhibitor was developed based on a recently reported, highly selective thiol scaffold. Using X-ray crystallography, the lack of inhibition of a range of human matrix metalloproteases could be attributed to a distinct binding mode sparing the S1' pocket. The inhibitor was shown to restore the effect of the antimicrobial peptide LL-37, decrease the formation of P. aeruginosa biofilm and, for the first time for a LasB inhibitor, reduce the release of extracellular DNA. Hence, it is capable of disrupting several important bacterial resistance mechanisms. These results highlight the potential of protease inhibitors to fight bacterial infections and point out the possibility to achieve selective inhibition even with a strong zinc anchor.
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http://dx.doi.org/10.1021/acschembio.8b00257DOI Listing
September 2018

Design and synthesis of novel annulated thienopyrimidines as phosphodiesterase 5 (PDE5) inhibitors.

Arch Pharm (Weinheim) 2018 May 14;351(5):e1800018. Epub 2018 Apr 14.

Faculty of Pharmacy and Biotechnology, Department of Pharmaceutical Chemistry, German University in Cairo, Cairo, Egypt.

Novel cycloalkene-fused thienopyrimidine analogues with enhanced phosphodiesterase 5 (PDE5) inhibitory properties are presented. The structure of the reported scaffold was modulated through variation of the terminal cycloalkene ring size, as well as by varying the substituents at position 4 through the attachment of different groups including aniline, benzylamine, cyclohexylethylamine, methyl/acetyl/aryl piperazines, and aryl hydrazones. Compound 15Y with a benzylamine substituent and cycloheptene as terminal ring showed the highest PDE5 inhibitory activity with an IC value as low as 190 nM and with good selectivity versus PDE7 and PDE9.
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http://dx.doi.org/10.1002/ardp.201800018DOI Listing
May 2018