TY - JOUR A1 - Wohlfart, Jonas A1 - Holzgrabe, Ulrike T1 - Analysis of histamine and sisomicin in gentamicin: search for the causative agents of adverse effects JF - Archiv der Pharmazie N2 - In 1998, the aminoglycoside antibiotic gentamicin sulfate caused several cases of deaths in the United States, after the switch from twice- to once-daily application. Endotoxins were discussed as the cause for the adverse effects and sisomicin was identified as the lead impurity; batches containing sisomicin were contaminated with more impurities and were responsible for the fatalities. In 2016, anaphylactic reactions in horses, and later in humans with one fatality, were observed after application of gentamicin sulfate contaminated with histamine. To determine whether histamine was responsible for the 1990s death cases as well, histamine was quantified by means of liquid chromatography–tandem mass spectrometry (LC-MS/MS) in 30 samples of gentamicin sulfate analyzed in previous studies. Furthermore, a relative quantification of sisomicin was performed to check for a correlation between histamine and the lead impurity. A maximum amount of 11.52 ppm histamine was detected, which is below the limit for anaphylactic reactions of 16 ppm, and no correlation of the two impurities was observed. However, the European Medicines Agency recommends a stricter limit with regard to the maximum single dose of gentamicin sulfate to reach a greater gap between the maximum histamine exposition of 4.3 µg and the quantity known to cause hypotension of 7 µg. The low amounts of histamine and the fact that there is no connection with the contamination with sisomicin showed that histamine was not the cause for the death cases in the United States in 1998, and endotoxins remain the most probable explanation. KW - chemistry KW - sisomicin KW - drug impurities KW - gentamicin sulfate KW - histamine KW - LC-MS/MS Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256596 VL - 354 IS - 12 ER - TY - JOUR A1 - Walther, Rasmus A1 - Krmar, Jovana A1 - Leistner, Adrian A1 - Svrkota, Bojana A1 - Otašević, Biljana A1 - Malenović, Andjelija A1 - Holzgrabe, Ulrike A1 - Protić, Ana T1 - Analytical Quality by Design: achieving robustness of an LC-CAD method for the analysis of non-volatile fatty acids JF - Pharmaceuticals N2 - An alternative to the time-consuming and error-prone pharmacopoeial gas chromatography method for the analysis of fatty acids (FAs) is urgently needed. The objective was therefore to propose a robust liquid chromatography method with charged aerosol detection for the analysis of polysorbate 80 (PS80) and magnesium stearate. FAs with different numbers of carbon atoms in the chain necessitated the use of a gradient method with a Hypersil Gold C\(_{18}\) column and acetonitrile as organic modifier. The risk-based Analytical Quality by Design approach was applied to define the Method Operable Design Region (MODR). Formic acid concentration, initial and final percentages of acetonitrile, gradient elution time, column temperature, and mobile phase flow rate were identified as critical method parameters (CMPs). The initial and final percentages of acetonitrile were fixed while the remaining CMPs were fine-tuned using response surface methodology. Critical method attributes included the baseline separation of adjacent peaks (α-linolenic and myristic acid, and oleic and petroselinic acid) and the retention factor of the last compound eluted, stearic acid. The MODR was calculated by Monte Carlo simulations with a probability equal or greater than 90%. Finally, the column temperature was set at 33 °C, the flow rate was 0.575 mL/min, and acetonitrile linearly increased from 70 to 80% (v/v) within 14.2 min. KW - Analytical Quality by Design KW - fatty acids KW - charged aerosol detector KW - polysorbate 80 KW - magnesium stearate Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-311265 SN - 1424-8247 VL - 16 IS - 4 ER - TY - JOUR A1 - Volpato, Daniela A1 - Kauk, Michael A1 - Messerer, Regina A1 - Bermudez, Marcel A1 - Wolber, Gerhard A1 - Bock, Andreas A1 - Hoffmann, Carsten A1 - Holzgrabe, Ulrike T1 - The Role of Orthosteric Building Blocks of Bitopic Ligands for Muscarinic M1 Receptors JF - ACS Omega N2 - The muscarinic M\(_1\) acetylcholine receptor is an important drug target for the treatment of various neurological disorders. Designing M\(_1\) receptor-selective drugs has proven challenging, mainly due to the high conservation of the acetylcholine binding site among muscarinic receptor subtypes. Therefore, less conserved and topographically distinct allosteric binding sites have been explored to increase M\(_1\) receptor selectivity. In this line, bitopic ligands, which target orthosteric and allosteric binding sites simultaneously, may provide a promising strategy. Here, we explore the allosteric, M1-selective BQCAd scaffold derived from BQCA as a starting point for the design, synthesis, and pharmacological evaluation of a series of novel bitopic ligands in which the orthosteric moieties and linker lengths are systematically varied. Since β-arrestin recruitment seems to be favorable to therapeutic implication, all the compounds were investigated by G protein and β-arrestin assays. Some bitopic ligands are partial to full agonists for G protein activation, some activate β-arrestin recruitment, and the degree of β-arrestin recruitment varies according to the respective modification. The allosteric BQCAd scaffold controls the positioning of the orthosteric ammonium group of all ligands, suggesting that this interaction is essential for stimulating G protein activation. However, β-arrestin recruitment is not affected. The novel set of bitopic ligands may constitute a toolbox to study the requirements of β-arrestin recruitment during ligand design for therapeutic usage. KW - muscarinic M1 receptor Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230548 VL - 5 IS - 49 ER - TY - JOUR A1 - Volpato, Daniela A1 - Holzgrabe, Ulrike T1 - Designing Hybrids Targeting the Cholinergic System by Modulating the Muscarinic and Nicotinic Receptors: A Concept to Treat Alzheimer’s Disease JF - Molecules N2 - The cholinergic hypothesis has been reported first being the cause of memory dysfunction in the Alzheimer’s disease. Researchers around the globe have focused their attention on understanding the mechanisms of how this complicated system contributes to processes such as learning, memory, disorientation, linguistic problems, and behavioral issues in the indicated chronic neurodegenerative disease. The present review reports recent updates in hybrid molecule design as a strategy for selectively addressing multiple target proteins involved in Alzheimer’s disease (AD) and the study of their therapeutic relevance. The rationale and the design of the bifunctional compounds will be discussed in order to understand their potential as tools to investigate the role of the cholinergic system in AD. KW - AChE inhibitor KW - Alzheimer’s disease KW - bitopic ligand KW - cholinergic system KW - hybrid molecules KW - muscarinic receptors KW - nicotinic receptors Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197555 SN - 1420-3049 VL - 23 IS - 12 ER - TY - JOUR A1 - Urlaub, Jonas A1 - Kaiser, Reinhard P. A1 - Scherf‐Clavel, Oliver A1 - Bolm, Carsten A1 - Holzgrabe, Ulrike T1 - Investigation of isomerization of dexibuprofen in a ball mill using chiral capillary electrophoresis JF - Electrophoresis N2 - Besides the racemate, the S‐enantiomer of ibuprofen (Ibu) is used for the treatment of inflammation and pain. Since the configurational stability of S‐Ibu in solid state is of interest, it was studied by means of ball milling experiments. For the evaluation of the enantiomeric composition, a chiral CE method was developed and validated according to the ICH guideline Q2(R1). The addition of Mg\(^{2+}\), Ca\(^{2+}\), or Zn\(^{2+}\) ions to the background electrolyte (BGE) was found to improve Ibu enantioresolution. Chiral separation of Ibu enantiomers was achieved on a 60.2 cm (50.0 cm effective length) x 75 μm fused‐silica capillary using a background electrolyte (BGE) composed of 50 mM sodium acetate, 10 mM magnesium acetate tetrahydrate, and 35 mM heptakis‐(2,3,6‐tri‐O‐methyl)‐β‐cyclodextrin (TM‐β‐CD) as chiral selector. The quantification of R‐Ibu in the mixture was performed using the normalization procedure. Linearity was evaluated in the range of 0.68–5.49% R‐Ibu (R\(^{2}\) = 0.999), recovery was found to range between 97 and 103%, the RSD of intra‐ and interday precision below 2.5%, and the limit of quantification for R‐ in S‐Ibu was calculated to be 0.21% (extrapolated) and 0.15% (dilution of racemic ibuprofen), respectively. Isomerization of S‐Ibu was observed under basic conditions by applying long milling times and high milling frequencies. KW - capillary electrophoresis KW - chiral separation KW - Ibuprofen KW - isomerization KW - validation Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225852 VL - 42 IS - 17-18 SP - 1790 EP - 1799 ER - TY - JOUR A1 - Triyasmono, Liling A1 - Schollmayer, Curd A1 - Schmitz, Jens A1 - Hovah, Emilie A1 - Lombo, Cristian A1 - Schmidt, Sebastian A1 - Holzgrabe, Ulrike T1 - Simultaneous determination of the saponification value, acid value, ester value, and iodine value in commercially available red fruit oil (Pandanus conoideus, Lam.) using \(^1\)H qNMR spectroscopy JF - Food Analytical Methods N2 - Red fruit oil (RFO) can be extracted from fruits of Pandanus conoideus, Lam., an endogenous plant of Papua, Indonesia. It is a commonly used essential original traditional medicine. By applying a newly developed quantitative \(^1\)H NMR (qNMR) spectroscopy method for quality assessment, a simultaneous determination of the saponification value (SV), acid value (AV), ester value (EV), and iodine value (IV) in RFO was possible. Dimethyl sulfone (DMSO\(_2\)) was used as an internal standard. Optimization of NMR parameters, such as NMR pulse sequence, relaxation delay time, and receiver gain, finally established the \(^1\)H NMR-based quantification approach. Diagnostic signals of the internal standard at δ = 2.98 ppm, SV at δ = 2.37–2.20 ppm, AV at δ = 2.27–2.20 ppm, EV at δ = 2.37–2.27 ppm, and IV at δ = 5.37–5.27 ppm, respectively, were used for quantitative analysis. The method was validated concerning linearity (R\(^2\) = 0.999), precision (less than 0.83%), and repeatability in the range 99.17–101.17%. Furthermore, this method was successfully applied to crude RFO, crude RFO with palmitic and oleic acid addition, and nine commercial products. The qNMR results for the respective fat values are in accordance with the results of standard methods, as can be seen from the F- and t-test (< 1.65 and < 1.66, respectively). The fundamental advantages of qNMR, such as its rapidity and simplicity, make it a feasible and existing alternative to titration for the quality control of RFO. KW - quantitative 1H NMR KW - saponification Value KW - acid value KW - ester value KW - iodine value KW - red fruit oil Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-324728 SN - 1936-9751 VL - 16 IS - 1 ER - TY - JOUR A1 - Shah, Nirav R. A1 - Bulitta, Jürgen B. A1 - Kinzig, Martina A1 - Landersdorfer, Cornelia B. A1 - Jiao, Yuanyuan A1 - Sutaria, Dhruvitkumar S. A1 - Tao, Xun A1 - Höhl, Rainer A1 - Holzgrabe, Ulrike A1 - Kees, Frieder A1 - Stephan, Ulrich A1 - Sörgel, Fritz T1 - Novel population pharmacokinetic approach to explain the differences between cystic fibrosis patients and healthy volunteers via protein binding JF - Pharmaceutics N2 - The pharmacokinetics in patients with cystic fibrosis (CF) has long been thought to differ considerably from that in healthy volunteers. For highly protein bound β-lactams, profound pharmacokinetic differences were observed between comparatively morbid patients with CF and healthy volunteers. These differences could be explained by body weight and body composition for β-lactams with low protein binding. This study aimed to develop a novel population modeling approach to describe the pharmacokinetic differences between both subject groups by estimating protein binding. Eight patients with CF (lean body mass [LBM]: 39.8 ± 5.4kg) and six healthy volunteers (LBM: 53.1 ± 9.5kg) received 1027.5 mg cefotiam intravenously. Plasma concentrations and amounts in urine were simultaneously modelled. Unscaled total clearance and volume of distribution were 3% smaller in patients with CF compared to those in healthy volunteers. After allometric scaling by LBM to account for body size and composition, the remaining pharmacokinetic differences were explained by estimating the unbound fraction of cefotiam in plasma. The latter was fixed to 50% in male and estimated as 54.5% in female healthy volunteers as well as 56.3% in male and 74.4% in female patients with CF. This novel approach holds promise for characterizing the pharmacokinetics in special patient populations with altered protein binding. KW - cystic fibrosis patients KW - healthy volunteers KW - cefotiam KW - beta-lactam antibiotics KW - population pharmacokinetics KW - protein binding KW - allometric scaling KW - body size KW - body composition KW - S-ADAPT Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196934 SN - 1999-4923 VL - 11 IS - 6 ER - TY - JOUR A1 - Seitzer, Moritz A1 - Klapper, Sylvia A1 - Mazigo, Humphrey D. A1 - Holzgrabe, Ulrike A1 - Mueller, Andreas T1 - Quality and composition of Albendazole, Mebendazole and Praziquantel available in Burkina Faso, Côte d’Ivoire, Ghana and Tanzania JF - PLoS Neglected Tropical Diseases N2 - Background Even though the international combat against Neglected Tropical Diseases such as schistosomiasis or soil-transmitted helminthiases depends on reliable therapeutics, anthelminthic pharmacovigilance has been neglected on many national African drug markets. Therefore, quality and composition of Albendazole, Mebendazole and Praziquantel locally collected in Burkina Faso, Côte d’Ivoire, Ghana and Tanzania were analysed. Methods Samples of 88 different batches were obtained from randomly selected facilities. Sampling took place in Northwest Tanzania, Western Burkina Faso, Southeast Côte d’Ivoire and Southwest Ghana. Visual examination of both packaging and samples was performed according to the WHO ‘Be Aware’ tool. Products were then screened with the GPHF Minilab, consisting of tests of mass uniformity, disintegration times and thin-layer chromatography (TLC). Confirmatory tests were performed according to international pharmacopoeiae, applying assays for dissolution profiles and high-performance liquid chromatography (HPLC). Findings Despite minor irregularities, appearance of the products did not hint at falsified medicines. However, 19.6% of the brands collected in Ghana and Tanzania were not officially licensed for sale. Mass uniformity was confirmed in 53 out of 58 brands of tablets. 41 out of 56 products passed disintegration times; 10 out of the 15 failing products did not disintegrate at all. Evaluating TLC results, only 4 out of 83 batches narrowly missed specification limits, 18 batches slightly exceeded them. Not more than 46.3% (31 / 67) of the tablets assayed passed the respective pharmaceutical criteria for dissolution. HPLC findings confirmed TLC results despite shifted specification limits: 10 out of 83 tested batches contained less than 90%, none exceeded 110%. Conclusion In the four study countries, no falsified anthelminthic medicine was encountered. The active pharmaceutical ingredient was not found to either exceed or fall below specification limits. Galenic characteristics however, especially dissolution profiles, revealed great deficits. KW - thin-layer chromatography KW - high performance liquid chromatography KW - Schistosomiasis KW - acetonitrile KW - acetic acid KW - Tanzania KW - veterinarians KW - veterinary medicine Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-270434 VL - 15 IS - 1 ER - TY - JOUR A1 - Schmidt, Sebastian A1 - Zehe, Markus A1 - Holzgrabe, Ulrike T1 - Characterization of binding properties of ephedrine derivatives to human alpha-1-acid glycoprotein JF - European Journal of Pharmaceutical Sciences N2 - Most drugs, especially those with acidic or neutral moieties, are bound to the plasma protein albumin, whereas basic drugs are preferentially bound to human alpha-1-acid glycoprotein (AGP). The protein binding of the long-established drugs ephedrine and pseudoephedrine, which are used in the treatment of hypotension and colds, has so far only been studied with albumin. Since in a previous study a stereoselective binding of ephedrine and pseudoephedrine to serum but not to albumin was observed, the aim of this study was to check whether the enantioselective binding behavior of ephedrine and pseudoephedrine, in addition to the derivatives methylephedrine and norephedrine, is due to AGP and to investigate the influence of their different substituents and steric arrangement. Discontinuous ultrafiltration was used for the determination of protein binding. Characterization of ligand-protein interactions of the drugs was obtained by saturation transfer difference nuclear magnetic resonance spectroscopy. Docking experiments were performed to analyze possible ligand-protein interactions. The more basic the ephedrine derivative is, the higher is the affinity to AGP. There was no significant difference in the binding properties between the individual enantiomers and the diastereomers of ephedrine and pseudoephedrine. KW - protein binding KW - AGP KW - ultrafiltration KW - saturation transfer difference NMR KW - epitope mapping KW - ephedrine Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300848 VL - 181 ER - TY - JOUR A1 - Schmidt, Sebastian A1 - Holzgrabe, Ulrike T1 - Method development, optimization, and validation of the separation of ketamine enantiomers by capillary electrophoresis using design of experiments JF - Chromatographia N2 - Capillary electrophoresis was chosen as cost-effective and robust method to separate ketamine enantiomers. For the method development, first different native and modified cyclodextrins were tested. The most promising chiral selector was α-cyclodextrin. A design of experiments (DoE) was carried out, which started with the screening of relevant factors. Based on these results, the method was optimized according to the significant factors (buffer, cyclodextrin concentration, pH value, voltage, temperature) of the screening based on the response resolution and migration time of the later migrating enantiomer. The optimized conditions consisted of a background electrolyte with 275 mM TRIS, adjusted with 85% phosphoric acid to a pH of 2.50, and 50 mM α-cyclodextrin, at a temperature of 15 °C, an applied voltage of 30 kV and an injection pressure of 1.0 psi for 10 s. A fused-silica capillary with a total length of 70 cm and an effective length to the detector of 60 cm was used. The method was validated according to ICH guideline Q2 R(1). The limit of quantification was 3.51 µg mL\(^{−1}\) for S-ketamine and 3.98 µg mL\(^{−1}\)for R-ketamine. The method showed good linearity for racemic ketamine with R\(^2\) of 0.9995 for S-ketamine and 0.9994 for R-ketamine. The lowest quantifiable content of S-ketamine found in R-ketamine was 0.45%. KW - ketamine KW - capillary electrophoresis KW - design of experiments KW - cyclodextrins KW - enantiomers Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-324713 SN - 0009-5893 VL - 86 IS - 1 ER - TY - JOUR A1 - Schmidt, Sebastian A1 - Holzgrabe, Ulrike T1 - Do the enantiomers of ketamine bind enantioselectively to human serum albumin? JF - European Journal of Pharmaceutical Sciences N2 - The binding of drugs to plasma proteins is an important process in the human body and has a significant influence on pharmacokinetic parameter. Human serum albumin (HSA) has the most important function as a transporter protein. The binding of ketamine to HSA has already been described in literature, but only of the racemate. The enantiomerically pure S-ketamine is used as injection solution for induction of anesthesia and has been approved by the Food and Drug Administration for the therapy of severe depression as a nasal spray in 2019. The question arises if there is enantioselective binding to HSA. Hence, the aim of this study was to investigate whether there is enantioselective binding of S-and R-ketamine to HSA or not. Ultrafiltration (UF) followed by chiral capillary electrophoretic analysis was used to determine the extent of protein binding. Bound fraction to HSA was 71.2 % and 64.9 % for enantiomerically pure R- and S-ketamine, respectively, and 66.5 % for the racemate. Detailed binding properties were studied by Saturation Transfer Difference (STD)-, waterLOGSY- and Carr-Purcell-Meiboom-Gill (CPMG)-NMR spectroscopy. With all three methods, the aromatic ring and the N-methyl group could be identified as the structural moieties most strongly involved in binding of ketamine to HSA. pK\(_{aff}\) values determined using UF and NMR indicate that ketamine is a weak affinity ligand to HSA and no significant differences in binding behavior were found between the individual enantiomers and the racemate. KW - protein binding KW - albumin KW - electrophoresis KW - nuclear magnetic resonance spectroscopy KW - ultrafiltration KW - enantioselectivity Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349791 VL - 192 ER - TY - JOUR A1 - Schmidt, Marianne A1 - Skaf, Josef A1 - Gavril, Georgiana A1 - Polednik, Christine A1 - Roller, Jeanette A1 - Kessler, Michael A1 - Holzgrabe, Ulrike T1 - The influence of Osmunda regalis root extract on head and neck cancer cell proliferation, invasion and gene expression JF - BMC Complementary and Alternative Medicine N2 - Background: According to only a handful of historical sources, Osmunda regalis, the royal fern, has been used already in the middle age as an anti-cancer remedy. To examine this ancient cancer cure, an ethanolic extract of the roots was prepared and analysed in vitro on its effectiveness against head and neck cancer cell lines. Methods: Proliferation inhibition was measured with the MTT assay. Invasion inhibition was tested in a spheroid-based 3-D migration assay on different extracellular matrix surfaces. Corresponding changes in gene expression were analysed by qRT-PCR array. Induction of apoptosis was measured by fluorescence activated cell sorting (FACS) with the Annexin V binding method. The plant extract was analysed by preliminary phytochemical tests, liquid chromatography/mass spectroscopy (LC-MS) and thin layer chromatography (TLC). Anti-angiogenetic activity was determined by the tube formation assay. Results: O. regalis extract revealed a growth inhibiting effect on the head and neck carcinoma cell lines HLaC78 and FaDu. The toxic effect seems to be partially modulated by p-glycoprotein, as the MDR-1 expressing HLaC79-Tax cells were less sensitive. O. regalis extract inhibited the invasion of cell lines on diverse extracellular matrix substrates significantly. Especially the dispersion of the highly motile cell line HlaC78 on laminin was almost completely abrogated. Motility inhibition on laminin was accompanied by differential gene regulation of a variety of genes involved in cell adhesion and metastasis. Furthermore, O. regalis extract triggered apoptosis in HNSCC cell lines and inhibited tube formation of endothelial cells. Preliminary phytochemical analysis proved the presence of tannins, glycosides, steroids and saponins. Liquid chromatography/mass spectroscopy (LC-MS) revealed a major peak of an unknown substance with a molecular mass of 864.15 Da, comprising about 50% of the total extract. Thin layer chromatography identified ferulic acid to be present in the extract. Conclusion: The presented results justify the use of royal fern extracts as an anti-cancer remedy in history and imply a further analysis of ingredients. KW - head and neck carcinoma KW - invasion KW - plant extract KW - proliferation KW - HNSCC KW - metastasis KW - gene expression KW - Osmunda regalis Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158704 VL - 17 IS - 518 ER - TY - JOUR A1 - Scheuplein, Nicolas Julian A1 - Lohr, Theresa A1 - Vivoli Vega, Mirella A1 - Ankrett, Dyan A1 - Seufert, Florian A1 - Kirchner, Lukas A1 - Harmer, Nicholas J. A1 - Holzgrabe, Ulrike T1 - Fluorescent probe for the identification of potent inhibitors of the macrophage infectivity potentiator (Mip) protein of Burkholderia pseudomallei JF - SLAS Discovery N2 - Highlights • Synthesis of a new tracer molecule. • Robust and easy screening method for a broad range of compound activities. • FP assay validation considering limited use of starting material, DMSO tolerance, variation in incubation time and temperature. • Possibility of extension to HTP assay. Abstract The macrophage infectivity potentiator (Mip) protein belongs to the immunophilin superfamily. This class of enzymes catalyzes the interconversion between the cis and trans configuration of proline-containing peptide bonds. Mip has been shown to be important for the virulence of a wide range of pathogenic microorganisms, including the Gram-negative bacterium Burkholderia pseudomallei. Small molecules derived from the natural product rapamycin, lacking its immunosuppression-inducing moiety, inhibit Mip's peptidyl-prolyl cis-trans isomerase (PPIase) activity and lead to a reduction in pathogen load in vitro. Here, a fluorescence polarization assay (FPA) to enable the screening and effective development of BpMip inhibitors was established. A fluorescent probe was prepared, derived from previous pipecolic scaffold Mip inhibitors labeled with fluorescein. This probe showed moderate affinity for BpMip and enabled a highly robust FPA suitable for screening large compound libraries with medium- to high-throughput (Z factor ∼ 0.89) to identify potent new inhibitors. The FPA results are consistent with data from the protease-coupled PPIase assay. Analysis of the temperature dependence of the probe's binding highlighted that BpMip's ligand binding is driven by enthalpic rather than entropic effects. This has considerable consequences for the use of low-temperature kinetic assays. KW - PPIase KW - fluorescence polarization KW - anisotropy KW - high throughput screening KW - Burkholderia pseudomallei Mip KW - Mip inhibitor Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349784 VL - 28 IS - 5 ER - TY - JOUR A1 - Rösing, Nils A1 - Salvador, Ellaine A1 - Güntzel, Paul A1 - Kempe, Christoph A1 - Burek, Malgorzata A1 - Holzgrabe, Ulrike A1 - Soukhoroukov, Vladimir A1 - Wunder, Christian A1 - Förster, Carola T1 - Neuroprotective Effects of Isosteviol Sodium in Murine Brain Capillary Cerebellar Endothelial Cells (cerebEND) After Hypoxia JF - Frontiers in Cellular Neuroscience N2 - Ischemic stroke is one of the leading causes of death worldwide. It damages neurons and other supporting cellular elements in the brain. However, the impairment is not only confined to the region of assault but the surrounding area as well. Besides, it also brings about damage to the blood-brain barrier (BBB) which in turn leads to microvascular failure and edema. Hence, this necessitates an on-going, continuous search for intervention strategies and effective treatment. Of late, the natural sweetener stevioside proved to exhibit neuroprotective effects and therapeutic benefits against cerebral ischemia-induced injury. Its injectable formulation, isosteviol sodium (STVNA) also demonstrated favorable results. Nonetheless, its effects on the BBB have not yet been investigated to date. As such, this present study was designed to assess the effects of STVNA in our in vitro stroke model of the BBB.The integrity and permeability of the BBB are governed and maintained by tight junction proteins (TJPs) such as claudin-5 and occludin. Our data show increased claudin-5 and occludin expression in oxygen and glucose (OGD)-deprived murine brain capillary cerebellar endothelial cells (cerebEND) after STVNa treatment. Likewise, the upregulation of the transmembrane protein integrin-αv was also observed. Finally, cell volume was reduced with the simultaneous administration of STVNA and OGD in cerebEND cells. In neuropathologies such as stroke, the failure of cell volume control is a major feature leading to loss of cells in the penumbra as well as adverse outcomes. Our initial findings, therefore, point to the neuroprotective effects of STVNA at the BBB in vitro, which warrant further investigation for a possible future clinical intervention. KW - isosteviol sodium KW - hypoxia KW - cerebEND cells KW - blood brain barrier KW - neuroprotection Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-215013 SN - 1662-5102 VL - 14 ER - TY - JOUR A1 - Riad, Noura M. A1 - Zlotos, Darius P. A1 - Holzgrabe, Ulrike T1 - Crystal structure of 5,11-dihydropyrido[2,3-b][1,4]benzodiazepin-6-one. JF - Acta Crystallographica Section E Crystallographic Communications N2 - The title compound, C\(_{12}\)H\(_{9}\)N\(_{3}\)O, is an inter­mediate in the synthesis of the muscarinic M2 receptor antagonist AFDX-384. The seven-membered ring adopts a boat conformation and the dihedral angle between the planes of the aromatic rings is 41.51 (9)°. In the crystal, mol­ecules are linked into [001] chains of alternating inversion dimers formed by pairs of N-H・・・O hydrogen bonds and pairs of N-H・・・N hydrogen bonds. In both cases, R\(_{2}\)\(^{2}\)(8) loops are generated. KW - crystal structure KW - pyridobenzodiazepine KW - boat conformation KW - hydrogen bonding Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149627 VL - E71 ER - TY - JOUR A1 - Rasheed, Huma A1 - Höllein, Ludwig A1 - Holzgrabe, Ulrike T1 - Future information technology tools for fighting substandard and falsified medicines in low- and middle-income countries JF - Frontiers in Pharmacology N2 - Substandard and falsified (SF) medicines have emerged as a global public health issue within the last two decades especially in low- and middle-income countries (LMICs). Serious consequences of this problem include a loss of trust and increased financial costs due to less disease control and more frequent complications during therapy. Of note, antimicrobial resistance is an additional long-term implication of poor-quality antimicrobials. This review covers information technology tools including medicines authentication tools (MAT) as mobile apps and messaging service, 2D barcoding approaches with drug safety alert systems, web based drug safety alerts, radiofrequency identification tags, databases to support visual inspection, digital aids to enhance the performance of quality evaluation kits, reference libraries for identification of falsified and substandard medicines, and quality evaluation kits based on machine learning for field testing. While being easy to access and simple to use, these initiatives are gaining acceptance in LMICs. Implementing 2D barcoding based on end-to-end verification and "Track and Trace" systems has emerged as a step toward global security in the supply chain. A breakthrough in web-based drug safety alert systems and data bases was the establishment of the Global Surveillance and Monitoring System by the World Health Organization in 2013. Future applications include concepts including "lab on a chip" and "paper analytical devices" and are claimed to be convenient and simple to use as well as affordable. The principles discussed herein are making profound impact in the fight against substandard and falsified medicines, offering cheap and accessible solutions. KW - track and trace KW - information technology KW - medicine authentication tools KW - mobile apps KW - quality evaluation KW - field testing KW - substandard and falsified medicines Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177068 VL - 9 IS - 995 ER - TY - JOUR A1 - Raschig, Martina A1 - Ramírez‐Zavala, Bernardo A1 - Wiest, Johannes A1 - Saedtler, Marco A1 - Gutmann, Marcus A1 - Holzgrabe, Ulrike A1 - Morschhäuser, Joachim A1 - Meinel, Lorenz T1 - Azobenzene derivatives with activity against drug‐resistant Candida albicans and Candida auris JF - Archiv der Pharmazie N2 - Increasing resistance against antimycotic drugs challenges anti‐infective therapies today and contributes to the mortality of infections by drug‐resistant Candida species and strains. Therefore, novel antifungal agents are needed. A promising approach in developing new drugs is using naturally occurring molecules as lead structures. In this work, 4,4'‐dihydroxyazobenzene, a compound structurally related to antifungal stilbene derivatives and present in Agaricus xanthodermus (yellow stainer), served as a starting point for the synthesis of five azobenzene derivatives. These compounds prevented the growth of both fluconazole‐susceptible and fluconazole‐resistant Candida albicans and Candida auris strains. Further in vivo studies are required to confirm the potential therapeutic value of these compounds. KW - antifungal drug KW - azobenzenes KW - Candida auris KW - Candida albicans Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312295 VL - 356 IS - 2 ER - TY - JOUR A1 - Penagos-Calvete, Diana A1 - Duque, Valeria A1 - Marimon, Claudia A1 - Parra, Diana M. A1 - Restrepo-Arango, Sandra K. A1 - Scherf-Clavel, Oliver A1 - Holzgrabe, Ulrike A1 - Montoya, Guillermo A1 - Salamanca, Constain H. T1 - Glycerolipid composition and advanced physicochemical considerations of sacha inchi oil toward cosmetic products formulation JF - Cosmetics N2 - Sacha inchi oil is a premier raw material with highly nutritional and functional features for the foodstuff, pharmaceutical, beauty, and personal care industries. One of the most important facts about this oil is the huge chemical content of unsaturated and polyunsaturated fatty acids. However, the current available information on the characterization of the triglyceride composition and the advance physicochemical parameters relevant to emulsion development is limited. Therefore, this research focused on providing a detailed description of the lipid composition using high-resolution tandem mass spectrometry and thorough physicochemical characterization to find the value of the required hydrophilic–lipophilic balance (HLB). For this, a study in the interfacial tension was evaluated, followed by the assessment of different parameters such as creaming index, droplet size, viscosity, zeta potential, pH, and electrical conductivity for a series emulsified at thermal stress condition. The results show that fatty acids are arranged into glycerolipids and the required HLB to achieve the maximum physical stability is around 8. KW - sacha inchi oil KW - unsaturated fatty acids KW - triacylglycerides KW - high-resolution tandem mass spectrometry KW - emulsions oil-in-water KW - required hydrophilic–lipophilic balance Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-193857 SN - 2079-9284 VL - 6 IS - 4 ER - TY - JOUR A1 - Pawellek, Ruben A1 - Krmar, Jovana A1 - Leistner, Adrian A1 - Djajić, Nevena A1 - Otašević, Biljana A1 - Protić, Ana A1 - Holzgrabe, Ulrike T1 - Charged aerosol detector response modeling for fatty acids based on experimental settings and molecular features: a machine learning approach JF - Journal of Cheminformatics N2 - The charged aerosol detector (CAD) is the latest representative of aerosol-based detectors that generate a response independent of the analytes' chemical structure. This study was aimed at accurately predicting the CAD response of homologous fatty acids under varying experimental conditions. Fatty acids from C12 to C18 were used as model substances due to semivolatile characterics that caused non-uniform CAD behaviour. Considering both experimental conditions and molecular descriptors, a mixed quantitative structure-property relationship (QSPR) modeling was performed using Gradient Boosted Trees (GBT). The ensemble of 10 decisions trees (learning rate set at 0.55, the maximal depth set at 5, and the sample rate set at 1.0) was able to explain approximately 99% (Q\(^2\): 0.987, RMSE: 0.051) of the observed variance in CAD responses. Validation using an external test compound confirmed the high predictive ability of the model established (R-2: 0.990, RMSEP: 0.050). With respect to the intrinsic attribute selection strategy, GBT used almost all independent variables during model building. Finally, it attributed the highest importance to the power function value, the flow rate of the mobile phase, evaporation temperature, the content of the organic solvent in the mobile phase and the molecular descriptors such as molecular weight (MW), Radial Distribution Function-080/weighted by mass (RDF080m) and average coefficient of the last eigenvector from distance/detour matrix (Ve2_D/Dt). The identification of the factors most relevant to the CAD responsiveness has contributed to a better understanding of the underlying mechanisms of signal generation. An increased CAD response that was obtained for acetone as organic modifier demonstrated its potential to replace the more expensive and environmentally harmful acetonitrile. KW - High-performance liquid chromatography (HPLC) KW - Charged aerosol detector (CAD) KW - Gradient boosted trees (GBT) KW - Quantitative structure-property relationship modeling (QSPR) KW - Fatty acids Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-261618 VL - 13 IS - 1 ER - TY - JOUR A1 - Montoya Peláez, Guillermo L. A1 - Sierra, Jelver A. A1 - Alzate, Fernando A1 - Holzgrabe, Ulrike A1 - Ramirez-Pineda, José R. T1 - Pentacyclic triterpenes from Cecropia telenitida with immunomodulatory activity on dendritic cells JF - Revista Brasileira de Farmacognosia - Brazilian Journal of Pharmacognosy N2 - Pentacyclic triterpenes are a large family of plant metabolites that exhibit a wide array of biological activities. The genus Cecropia, which encompasses many plant species, has been used as traditional medicine for the treatment of inflammatory diseases and is known to produce many active pentacyclic triterpenes. In this study we investigated the chemical composition of a pentacyclic triterpene fraction from the roots of Cecropia telenitida Cuatrec., Urticaceae. A novel compound, which we termed yarumic acid, and four known molecules (serjanic acid, spergulagenic acid A, 20-hydroxy-ursolic acid and goreishic acid I) were isolated and characterised. In a dendritic cell (DC)-based assay, we demonstrated that non-toxic doses of these pentacyclic triterpenes inhibited the secretion of at least one of the proinflammatory cytokines tested (IL-1 beta, IL-12p40, IL-12p70, TNF-alpha). Spergulagenic acid A also inhibited nitric oxide production in lipopolysaccharide-stimulated dendritic cell. Serjanic acid and spergulagenic acid A, which were the most potent abundant compounds in the pentacyclic triterpene fraction, showed the most activity in the dendritic cell-based assay. These results show that all pentacyclic triterpenes might contribute to the anti-inflammatory activities of C. telenitida. Moreover, yarumic acid as well as the four known pentacyclic triterpenes, can be exploited as potential immunomodulatory/anti-inflammatory agents. KW - psidium guajava; KW - oleanane saponins KW - kappa-B activation KW - cytokine production KW - chenopodium quinoa KW - obtusifolia bertol KW - nitric oxide KW - ursolic acid KW - bone marrow KW - macrophages KW - pentacyclic triterpene KW - dendritic cells KW - anti-inflammatory activity KW - cytokine modulation KW - natural product KW - cecropia telenitida Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131851 VL - 23 ER -