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Fittler H.,TU Darmstadt | Avrutina O.,TU Darmstadt | Empting M.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS | Kolmar H.,TU Darmstadt
Journal of Peptide Science | Year: 2014

Sunflower trypsin inhibitor-1 (SFTI-1), a bicyclic tetradecapeptide, has become a versatile tool as a scaffold for the development of the inhibitors of therapeutically relevant serine proteases, among them matriptase and kallikreins. Herein, we report the rational design of potent monocyclic and bicyclic inhibitors of human matriptase-1. We found that the presence of positive charge and lack of bulky residues at the peptide N-terminus is required for the maintenance of inhibitory activity. Replacement of the N-terminal glycine residue by lysine allowed for the chemical conjugation with a fluorophor via the ε-amino group without significant loss of inhibitory activity. Head-to-tail and side-chain-to-tail cyclization resulted in potent inhibitors with comparable activities against matriptase-1. The most potent synthetic bicyclic inhibitor found in this study (Ki = 2.6 nM at pH 7.6) is a truncated version of SFTI-1 (cyclo-KRCTKSIPPRCH) lacking a C-terminal proline and aspartate residue. It combines an internal disulfide bond with a peptide macrocycle that is formed through side-chain-to-tail cyclization of the ε-amino group of an N-terminal lysine and a C-terminal proline. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.


Al-Soud Y.A.,Saarland University | Al-Soud Y.A.,Al al-Bayt University | Heydel M.,Saarland University | Hartmann R.W.,Saarland University | Hartmann R.W.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS
Tetrahedron Letters | Year: 2011

A series of 1,3,5-trisubstituted 1,2,4-triazoles was designed and synthesized as potential inhibitors of ste-roidogenic CYP enzymes. The 1,2,4-triazole is part of the core structure fixing the geometry of the substances. A pyridine moiety was introduced as heme-binder. The target compounds were synthesized in two to four steps using silver carbonate mediated ring closure and Suzuki cross coupling reaction as key synthetic transformations. Biological testing of the synthesized compounds for the inhibition of the most important steroidogenic CYPs revealed compounds 29a and 30 as moderate inhibitors of aldo-sterone synthase (CYP11B2). © 2011 Elsevier Ltd. All rights reserved.


Titz A.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS
Topics in Medicinal Chemistry | Year: 2014

The Gram-negative bacterium Pseudomonas aeruginosa can establish life-threatening chronic infections through biofilm formation. The two bacterial lectins LecA and LecB play important roles in the formation of these biofilms and the inhibition of the lectins with carbohydrate-based ligands was shown to disrupt biofilms. These effects provide a novel therapeutic option against infections caused by P. aeruginosa. In addition to the urgent need for novel therapeutics against Pseudomonas infections, two major advantages arise from these lectins as targets for therapy: (1) the extracellular localization and site of activity of LecA and LecB circumvent the bacterial cell envelope as a particularly impermeable barrier of Gram-negative pathogens, which must be overcome by drugs against intracellular targets, and (2) the lectins are targets of the so-called anti-virulence therapy and therefore a reduced appearance of resistances towards lectin-directed drugs can be anticipated. In this review, the recent development of carbohydrate-based inhibitors against both lectins is summarized with a main focus on small molecules. © Springer-Verlag Berlin Heidelberg 2014.


Yin L.,Saarland University | Yin L.,ElexoPharm GmbH | Hu Q.,Saarland University | Emmerich J.,Saarland University | And 5 more authors.
Journal of Medicinal Chemistry | Year: 2014

Pathologically, high levels of aldosterone are associated with severe cardiovascular diseases such as congestive heart failure, hypertension, and myocardial fibrosis. The inhibition of aldosterone synthase (CYP11B2) to reduce aldosterone levels has been proposed as a promising treatment for diseases related to CYP11B2 because it is the crucial enzyme in the biosynthesis of aldosterone. A series of novel pyridyl- or isoquinolinyl-substituted indolines and indoles was designed via a ligand-based approach. The synthesized compounds were tested and found to be strong CYP11B2 inhibitors. The most potent ones showed IC50 values of less than 3 nM, being similarly potent as fadrozole and LCI699. Among them, compounds 14 and 23 showed good selectivity over the highly homologous CYP11B1, with selectivity factors (SF = IC 50 CYP11B1/IC50 CYP11B2) around 170; thus, they are superior to fadrozole and LCI699 (SFs < 15). These potent CYP11B2 inhibitors exhibited no inhibition (IC50 > 50 μM) of a panel of hepatic CYP enzymes including CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 and the crucial steroidogenic enzymes, CYP17 and CYP19. Because of these advantageous profiles, compounds 14 and 23 are considered to be candidates for further in vivo evaluation. © 2014 American Chemical Society.


Maurer C.K.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS | Steinbach A.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS | Hartmann R.W.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS | Hartmann R.W.,Saarland University
Journal of Pharmaceutical and Biomedical Analysis | Year: 2013

The appearance of antibiotic resistance requires novel therapeutic strategies. One approach is to selectively attenuate bacterial pathogenicity by interfering with bacterial cell-to-cell communication known as quorum sensing. The PQS quorum sensing system of Pseudomonas aeruginosa employs as signal molecule the Pseudomonas Quinolone Signal (PQS; 2-heptyl-3-hydroxy-4-(1. H)-quinolone), a key contributor to virulence and biofilm formation. Thus, interference with PQS production is considered as promising approach for the development of novel anti-infectives. Therefore, in this study, we developed and validated an ultra-high performance liquid chromatographic-tandem mass spectrometric approach for reliable quantification of PQS in P. aeruginosa cultures for activity determination of new quorum sensing inhibitors. The poor chromatographic properties of PQS reported by others could be overcome by fast microwave-assisted acetylation. The validation procedure including matrix effects, recovery, process efficiency, selectivity, carry-over, accuracy and precision, stability of the processed sample, and limit of quantification demonstrated that the method fulfilled all requirements of common validation guidelines. Its applicability was successfully proven in routine testing. In addition, two-point calibration was shown to be applicable for fast and reliable PQS quantification saving time and resources. In summary, the described method provides a powerful tool for the discovery of new quorum sensing inhibitors as potential anti-infectives and illustrated the usefulness of chemical derivatization, acetylation, in liquid chromatography-mass spectrometry analysis. © 2013 Elsevier B.V.


Spadaro A.,Saarland University | Spadaro A.,ElexoPharm GmbH | Frotscher M.,Saarland University | Hartmann R.W.,Saarland University | Hartmann R.W.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS
Journal of Medicinal Chemistry | Year: 2012

17β-HSD1 is a novel target for the treatment of estrogen-dependent diseases, as it catalyzes intracellular estradiol formation. Starting from two recently described compounds, highly active and selective inhibitors were developed. Benzoyl 6 and benzamide 17 are the most selective compounds toward 17β-HSD2 described so far. They also showed a promising profile regarding activity in T47-D cells, selectivity toward ERα and ERβ, inhibition of hepatic CYP enzymes, metabolic stability, and inhibition of marmoset 17β-HSD1 and 17β-HSD2. © 2012 American Chemical Society.


Lucas S.,Saarland University | Negri M.,Saarland University | Heim R.,Saarland University | Zimmer C.,Saarland University | And 2 more authors.
Journal of Medicinal Chemistry | Year: 2011

Pyridine substituted 3,4-dihydro-1H-quinolin-2-ones (e.g., 1-3) constitute a class of highly potent and selective inhibitors of aldosterone synthase (CYP11B2), a promising target for the treatment of hyperaldosteronism, congestive heart failure, and myocardial fibrosis. Among these, ethyl-substituted 3 possesses high selectivity against CYP1A2. Rigidification of 3 by incorporation of the ethyl group into a 5- or 6-membered ring affords compounds with a pyrroloquinolinone or pyridoquinolinone molecular scaffold (e.g., 4 and 5). It was found that these molecules are even more potent and selective CYP11B2 inhibitors than their corresponding open-chain analogues. Moreover, pyrroloquinolinone 4 exhibits no inhibition of the six most important hepatic CYP enzymes as well as a bioavailability in the range of the marketed drug fadrozole. The SAR studies disclose that subtle changes in the heterocyclic moiety are responsible for either a strong or a weak inhibition of the highly homologous 11-hydroxylase (CYP11B1). These results are not only important for fine-tuning the selectivity of CYP11B2 inhibitors but also for the development of selective CYP11B1 inhibitors that are of interest for the treatment of Cushing's syndrome and metabolic syndrome. © 2011 American Chemical Society.


Spadaro A.,Saarland University | Spadaro A.,ElexoPharm GmbH | Negri M.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS | Marchais-Oberwinkler S.,Saarland University | And 2 more authors.
PLoS ONE | Year: 2012

17β-estradiol (E2), the most potent estrogen in humans, known to be involved in the development and progession of estrogen-dependent diseases (EDD) like breast cancer and endometriosis. 17β-HSD1, which catalyses the reduction of the weak estrogen estrone (E1) to E2, is often overexpressed in breast cancer and endometriotic tissues. An inhibition of 17β-HSD1 could selectively reduce the local E2-level thus allowing for a novel, targeted approach in the treatment of EDD. Continuing our search for new nonsteroidal 17β-HSD1 inhibitors, a novel pharmacophore model was derived from crystallographic data and used for the virtual screening of a small library of compounds. Subsequent experimental verification of the virtual hits led to the identification of the moderately active compound 5. Rigidification and further structure modifications resulted in the discovery of a novel class of 17β-HSD1 inhibitors bearing a benzothiazole-scaffold linked to a phenyl ring via keto- or amide-bridge. Their putative binding modes were investigated by correlating their biological data with features of the pharmacophore model. The most active keto-derivative 6 shows IC 50-values in the nanomolar range for the transformation of E1 to E2 by 17β-HSD1, reasonable selectivity against 17β-HSD2 but pronounced affinity to the estrogen receptors (ERs). On the other hand, the best amide-derivative 21 shows only medium 17β-HSD1 inhibitory activity at the target enzyme as well as fair selectivity against 17β-HSD2 and ERs. The compounds 6 and 21 can be regarded as first benzothiazole-type 17β-HSD1 inhibitors for the development of potential therapeutics. © 2012 Spadaro et al.


Krug S.J.,Saarland University | Hu Q.,Saarland University | Hartmann R.W.,Saarland University | Hartmann R.W.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS
Journal of Steroid Biochemistry and Molecular Biology | Year: 2013

A screening of structurally different steroid hormone synthesis inhibitors was performed in order to find a starting point for the development of a new inhibitor of the bifunctional steroidogenic enzyme CYP17A1. Emphasis was placed on determination of selectivity between the two catalytic steps, namely 17α-hydroxylase and C17,20-lyase. For that purpose a new inhibition assay has been developed. Hits identified within this novel assay demonstrated selective inhibition of CYP17A1 lyase activity, and thus mark the basis for the development of selective C17,20-lyase inhibitors for the treatment of prostate cancer. © 2012 Elsevier Ltd.


Guevel X.L.,Saarland University | Daum N.,Helmholtz Institute for Pharmaceutical Research Saarland HIPS | Schneider M.,Saarland University
Nanotechnology | Year: 2011

Human transferrin has been biolabelled with gold nanoclusters (Au NCs) using a simple, fast and non-toxic method. These nanocrystals (<2nm) are stabilized in the protein via sulfur groups and have a high fluorescence emission in the near infrared region (QY = 4.3%; λ em = 695nm). Structural investigation and photophysical measurements show a high population of clusters formed of 22-33 gold atoms covalently bound to the transferrin. In solutions with pH ranging from 5 to 10 and in buffer solutions (PBS, HEPES), those biolabelled proteins exhibit a good stability. No significant quenching effect of the fluorescent transferrin has been detected after iron loading of iron-free transferrin (apoTf) and in the presence of a specific polyclonal antibody. Additionally, antibody-induced agglomeration demonstrates no alteration in the protein activity and the receptor target ability. MTT and Vialight Plus tests show no cytotoxicity of these labelled proteins in cells (1νgml - 1-1mgml - 1). Cell line experiments (A549) indicate also an uptake of the iron loaded fluorescent proteins inside cells. These remarkable data highlight the potential of a new type of non-toxic fluorescent transferrin for imaging and targeting. © 2011 IOP Publishing Ltd.

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