@article{UrlaubKaiserScherf‐Claveletal.2021, author = {Urlaub, Jonas and Kaiser, Reinhard P. and Scherf-Clavel, Oliver and Bolm, Carsten and Holzgrabe, Ulrike}, title = {Investigation of isomerization of dexibuprofen in a ball mill using chiral capillary electrophoresis}, series = {Electrophoresis}, volume = {42}, journal = {Electrophoresis}, number = {17-18}, doi = {10.1002/elps.202000307}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225852}, pages = {1790 -- 1799}, year = {2021}, abstract = {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.}, language = {en} } @article{MasotaVoggHelleretal.2020, author = {Masota, Nelson E. and Vogg, Gerd and Heller, Eberhard and Holzgrabe, Ulrike}, title = {Comparison of extraction efficiency and selectivity between low-temperature pressurized microwave-assisted extraction and prolonged maceration}, series = {Archiv der Pharmazie}, volume = {353}, journal = {Archiv der Pharmazie}, number = {10}, doi = {10.1002/ardp.202000147}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218529}, year = {2020}, abstract = {Extraction is a key step in studying compounds from plants and other natural sources. The common use of high temperatures in pressurized microwave-assisted extraction (PMAE) makes it unsuitable for the extraction of compounds with low or unknown thermal stability. This study aimed at determining the suitability of low-temperature, short-time PMAE in attaining yields comparable to those of prolonged maceration at room temperature. Additionally, we explored the phytochemical differences of the extracts from both techniques. Maceration at room temperature for 24 hr and PMAE at 40-45°C and 10 bar for 30 min were carried out on 18 samples from 14 plant species at a solvent-to-feeds ratio of 10. The PMAE yields of 16 out of 18 samples were within the proportions of 91-139.2\% as compared with the respective extracts from maceration. Varying numbers of nonmatching peaks were noted in MS chromatograms of five extract pairs, indicating selective extraction of some compounds. Low-temperature PMAE can attain reasonable extraction efficiency with the added value of sparing compounds of low thermal stability. The method can also enable the recovery of compounds distinct from those obtained by maceration.}, language = {en} } @article{BechtSchollmayerMonakhovaetal.2021, author = {Becht, Alexander and Schollmayer, Curd and Monakhova, Yulia and Holzgrabe, Ulrike}, title = {Tracing the origin of paracetamol tablets by near-infrared, mid-infrared, and nuclear magnetic resonance spectroscopy using principal component analysis and linear discriminant analysis}, series = {Analytical and Bioanalytical Chemistry}, volume = {413}, journal = {Analytical and Bioanalytical Chemistry}, number = {11}, doi = {10.1007/s00216-021-03249-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265400}, pages = {3107-3118}, year = {2021}, abstract = {Most drugs are no longer produced in their own countries by the pharmaceutical companies, but by contract manufacturers or at manufacturing sites in countries that can produce more cheaply. This not only makes it difficult to trace them back but also leaves room for criminal organizations to fake them unnoticed. For these reasons, it is becoming increasingly difficult to determine the exact origin of drugs. The goal of this work was to investigate how exactly this is possible by using different spectroscopic methods like nuclear magnetic resonance and near- and mid-infrared spectroscopy in combination with multivariate data analysis. As an example, 56 out of 64 different paracetamol preparations, collected from 19 countries around the world, were chosen to investigate whether it is possible to determine the pharmaceutical company, manufacturing site, or country of origin. By means of suitable pre-processing of the spectra and the different information contained in each method, principal component analysis was able to evaluate manufacturing relationships between individual companies and to differentiate between production sites or formulations. Linear discriminant analysis showed different results depending on the spectral method and purpose. For all spectroscopic methods, it was found that the classification of the preparations to their manufacturer achieves better results than the classification to their pharmaceutical company. The best results were obtained with nuclear magnetic resonance and near-infrared data, with 94.6\%/99.6\% and 98.7/100\% of the spectra of the preparations correctly assigned to their pharmaceutical company or manufacturer.}, language = {en} } @article{MasotaOhlsenSchollmayeretal.2022, author = {Masota, Nelson E. and Ohlsen, Knut and Schollmayer, Curd and Meinel, Lorenz and Holzgrabe, Ulrike}, title = {Isolation and characterization of galloylglucoses effective against multidrug-resistant strains of Escherichia coli and Klebsiella pneumoniae}, series = {Molecules}, volume = {27}, journal = {Molecules}, number = {15}, issn = {1420-3049}, doi = {10.3390/molecules27155045}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286179}, year = {2022}, abstract = {The search for new antibiotics against multidrug-resistant (MDR), Gram-negative bacteria is crucial with respect to filling the antibiotics development pipeline, which is subject to a critical shortage of novel molecules. Screening of natural products is a promising approach for identifying antimicrobial compounds hosting a higher degree of novelty. Here, we report the isolation and characterization of four galloylglucoses active against different MDR strains of Escherichia coli and Klebsiella pneumoniae. A crude acetone extract was prepared from Paeonia officinalis Linnaeus leaves, and bioautography-guided isolation of active compounds from the extract was performed by liquid-liquid extraction, as well as open column, flash, and preparative chromatographic methods. Isolated active compounds were characterized and elucidated by a combination of spectroscopic and spectrometric techniques. In vitro antimicrobial susceptibility testing was carried out on E. coli and K. pneumoniae using 2 reference strains and 13 strains hosting a wide range of MDR phenotypes. Furthermore, in vivo antibacterial activities were assessed using Galleria mellonella larvae, and compounds 1,2,3,4,6-penta-O-galloyl-β-d-glucose, 3-O-digalloyl-1,2,4,6-tetra-O-galloyl-β-d-glucose, 6-O-digalloyl-1,2,3,4-tetra-O-galloyl-β-d-glucose, and 3,6-bis-O-digalloyl-1,2,4-tri-O-galloyl-β-d-glucose were isolated and characterized. They showed minimum inhibitory concentration (MIC) values in the range of 2-256 µg/mL across tested bacterial strains. These findings have added to the number of known galloylglucoses from P. officinalis and highlight their potential against MDR Gram-negative bacteria.}, language = {en} } @article{ScheupleinLohrVivoliVegaetal.2023, author = {Scheuplein, Nicolas Julian and Lohr, Theresa and Vivoli Vega, Mirella and Ankrett, Dyan and Seufert, Florian and Kirchner, Lukas and Harmer, Nicholas J. and Holzgrabe, Ulrike}, title = {Fluorescent probe for the identification of potent inhibitors of the macrophage infectivity potentiator (Mip) protein of Burkholderia pseudomallei}, series = {SLAS Discovery}, volume = {28}, journal = {SLAS Discovery}, number = {5}, doi = {10.1016/j.slasd.2023.03.004}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-349784}, pages = {211-222}, year = {2023}, abstract = {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.}, language = {en} } @article{SchmidtHolzgrabe2024, author = {Schmidt, Sebastian and Holzgrabe, Ulrike}, title = {Do the enantiomers of ketamine bind enantioselectively to human serum albumin?}, series = {European Journal of Pharmaceutical Sciences}, volume = {192}, journal = {European Journal of Pharmaceutical Sciences}, doi = {10.1016/j.ejps.2023.106640}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-349791}, year = {2024}, abstract = {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.}, language = {en} } @article{RoesingSalvadorGuentzeletal.2020, author = {R{\"o}sing, Nils and Salvador, Ellaine and G{\"u}ntzel, Paul and Kempe, Christoph and Burek, Malgorzata and Holzgrabe, Ulrike and Soukhoroukov, Vladimir and Wunder, Christian and F{\"o}rster, Carola}, title = {Neuroprotective Effects of Isosteviol Sodium in Murine Brain Capillary Cerebellar Endothelial Cells (cerebEND) After Hypoxia}, series = {Frontiers in Cellular Neuroscience}, volume = {14}, journal = {Frontiers in Cellular Neuroscience}, issn = {1662-5102}, doi = {10.3389/fncel.2020.573950}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-215013}, year = {2020}, abstract = {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.}, language = {en} } @article{PenagosCalveteDuqueMarimonetal.2019, author = {Penagos-Calvete, Diana and Duque, Valeria and Marimon, Claudia and Parra, Diana M. and Restrepo-Arango, Sandra K. and Scherf-Clavel, Oliver and Holzgrabe, Ulrike and Montoya, Guillermo and Salamanca, Constain H.}, title = {Glycerolipid composition and advanced physicochemical considerations of sacha inchi oil toward cosmetic products formulation}, series = {Cosmetics}, volume = {6}, journal = {Cosmetics}, number = {4}, issn = {2079-9284}, doi = {10.3390/cosmetics6040070}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193857}, year = {2019}, abstract = {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.}, language = {en} } @article{RasheedHoelleinHolzgrabe2018, author = {Rasheed, Huma and H{\"o}llein, Ludwig and Holzgrabe, Ulrike}, title = {Future information technology tools for fighting substandard and falsified medicines in low- and middle-income countries}, series = {Frontiers in Pharmacology}, volume = {9}, journal = {Frontiers in Pharmacology}, number = {995}, doi = {10.3389/fphar.2018.00995}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177068}, year = {2018}, abstract = {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.}, language = {en} } @article{ShahBulittaKinzigetal.2019, author = {Shah, Nirav R. and Bulitta, J{\"u}rgen B. and Kinzig, Martina and Landersdorfer, Cornelia B. and Jiao, Yuanyuan and Sutaria, Dhruvitkumar S. and Tao, Xun and H{\"o}hl, Rainer and Holzgrabe, Ulrike and Kees, Frieder and Stephan, Ulrich and S{\"o}rgel, Fritz}, title = {Novel population pharmacokinetic approach to explain the differences between cystic fibrosis patients and healthy volunteers via protein binding}, series = {Pharmaceutics}, volume = {11}, journal = {Pharmaceutics}, number = {6}, issn = {1999-4923}, doi = {10.3390/pharmaceutics11060286}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196934}, year = {2019}, abstract = {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.}, language = {en} }