@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{WillemsDettaBaldinietal.2024, author = {Willems, Suzanne and Detta, Elena and Baldini, Lorenzo and Tietz, Deniz and Trabocchi, Andrea and Brunschweiger, Andreas}, title = {Diversifying DNA-tagged amines by isocyanide multicomponent reactions for DNA-encoded library synthesis}, series = {ACS Omega}, volume = {9}, journal = {ACS Omega}, number = {7}, issn = {2470-1343}, doi = {10.1021/acsomega.3c07136}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-349809}, pages = {7719-7724}, year = {2024}, abstract = {In DNA-encoded library synthesis, amine-substituted building blocks are prevalent. We explored isocyanide multicomponent reactions to diversify DNA-tagged amines and reported the Ugi-azide reaction with high yields and a good substrate scope. In addition, the Ugi-aza-Wittig reaction and the Ugi-4-center-3-component reaction, which used bifunctional carboxylic acids to provide lactams, were explored. Five-, six-, and seven-membered lactams were synthesized from solid support-coupled DNA-tagged amines and bifunctional building blocks, providing access to structurally diverse scaffolds.}, language = {en} } @article{DieboldSchoenemannEilersetal.2023, author = {Diebold, Mathias and Sch{\"o}nemann, Lars and Eilers, Martin and Sotriffer, Christoph and Schindelin, Hermann}, title = {Crystal structure of a covalently linked Aurora-A-MYCN complex}, series = {Acta Crystallographica}, volume = {D79}, journal = {Acta Crystallographica}, doi = {10.1107/s2059798322011433}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318855}, pages = {1 -- 9}, year = {2023}, abstract = {Formation of the Aurora-A-MYCN complex increases levels of the oncogenic transcription factor MYCN in neuroblastoma cells by abrogating its degradation through the ubiquitin proteasome system. While some small-molecule inhibitors of Aurora-A were shown to destabilize MYCN, clinical trials have not been satisfactory to date. MYCN itself is considered to be `undruggable' due to its large intrinsically disordered regions. Targeting the Aurora-A-MYCN complex rather than Aurora-A or MYCN alone will open new possibilities for drug development and screening campaigns. To overcome the challenges that a ternary system composed of Aurora-A, MYCN and a small molecule entails, a covalently cross-linked construct of the Aurora-A-MYCN complex was designed, expressed and characterized, thus enabling screening and design campaigns to identify selective binders.}, language = {en} } @article{CataldiRaschigGutmannetal.2023, author = {Cataldi, Eleonora and Raschig, Martina and Gutmann, Marcus and Geppert, Patrick T. and Ruopp, Matthias and Schock, Marvin and Gerwe, Hubert and Bertermann, R{\"u}diger and Meinel, Lorenz and Finze, Maik and Nowak-Kr{\´o}l, Agnieszka and Decker, Michael and L{\"u}hmann, Tessa}, title = {Amber Light Control of Peptide Secondary Structure by a Perfluoroaromatic Azobenzene Photoswitch}, series = {ChemBioChem}, volume = {24}, journal = {ChemBioChem}, number = {5}, doi = {10.1002/cbic.202200570}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312480}, year = {2023}, abstract = {The incorporation of photoswitches into the molecular structure of peptides and proteins enables their dynamic photocontrol in complex biological systems. Here, a perfluorinated azobenzene derivative triggered by amber light was site-specifically conjugated to cysteines in a helical peptide by perfluoroarylation chemistry. In response to the photoisomerization (trans→cis) of the conjugated azobenzene with amber light, the secondary structure of the peptide was modulated from a disorganized into an amphiphilic helical structure.}, language = {en} } @article{RaschigRamirez‐ZavalaWiestetal.2023, author = {Raschig, Martina and Ram{\´i}rez-Zavala, Bernardo and Wiest, Johannes and Saedtler, Marco and Gutmann, Marcus and Holzgrabe, Ulrike and Morschh{\"a}user, Joachim and Meinel, Lorenz}, title = {Azobenzene derivatives with activity against drug-resistant Candida albicans and Candida auris}, series = {Archiv der Pharmazie}, volume = {356}, journal = {Archiv der Pharmazie}, number = {2}, doi = {10.1002/ardp.202200463}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312295}, year = {2023}, abstract = {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.}, language = {en} } @article{SchmidtZeheHolzgrabe2023, author = {Schmidt, Sebastian and Zehe, Markus and Holzgrabe, Ulrike}, title = {Characterization of binding properties of ephedrine derivatives to human alpha-1-acid glycoprotein}, series = {European Journal of Pharmaceutical Sciences}, volume = {181}, journal = {European Journal of Pharmaceutical Sciences}, doi = {10.1016/j.ejps.2022.106333}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300848}, year = {2023}, abstract = {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.}, language = {en} } @article{JedeHenzeMeinersetal.2023, author = {Jede, Christian and Henze, Laura J. and Meiners, Kirstin and Bogdahn, Malte and Wedel, Marcel and van Axel, Valeria}, title = {Development and application of a dissolution-transfer-partitioning system (DTPS) for biopharmaceutical drug characterization}, series = {Pharmaceutics}, volume = {15}, journal = {Pharmaceutics}, number = {4}, issn = {1999-4923}, doi = {10.3390/pharmaceutics15041069}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311149}, year = {2023}, abstract = {A variety of in vitro dissolution and gastrointestinal transfer models have been developed aiming to predict drug supersaturation and precipitation. Further, biphasic, one-vessel in vitro systems are increasingly applied to simulate drug absorption in vitro. However, to date, there is a lack of combining the two approaches. Therefore, the first aim of this study was to develop a dissolution-transfer-partitioning system (DTPS) and, secondly, to assess its biopredictive power. In the DTPS, simulated gastric and intestinal dissolution vessels are connected via a peristaltic pump. An organic layer is added on top of the intestinal phase, serving as an absorptive compartment. The predictive power of the novel DTPS was assessed to a classical USP II transfer model using a BCS class II weak base with poor aqueous solubility, MSC-A. The classical USP II transfer model overestimated simulated intestinal drug precipitation, especially at higher doses. By applying the DTPS, a clearly improved estimation of drug supersaturation and precipitation and an accurate prediction of the in vivo dose linearity of MSC-A were observed. The DTPS provides a useful tool taking both dissolution and absorption into account. This advanced in vitro tool offers the advantage of streamlining the development process of challenging compounds.}, language = {en} } @article{MateraKaukCirilloetal.2023, author = {Matera, Carlo and Kauk, Michael and Cirillo, Davide and Maspero, Marco and Papotto, Claudio and Volpato, Daniela and Holzgrabe, Ulrike and De Amici, Marco and Hoffmann, Carsten and Dallanoce, Clelia}, title = {Novel Xanomeline-containing bitopic ligands of muscarinic acetylcholine receptors: design, synthesis and FRET investigation}, series = {Molecules}, volume = {28}, journal = {Molecules}, number = {5}, issn = {1420-3049}, doi = {10.3390/molecules28052407}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311249}, year = {2023}, abstract = {In the last few years, fluorescence resonance energy transfer (FRET) receptor sensors have contributed to the understanding of GPCR ligand binding and functional activation. FRET sensors based on muscarinic acetylcholine receptors (mAChRs) have been employed to study dual-steric ligands, allowing for the detection of different kinetics and distinguishing between partial, full, and super agonism. Herein, we report the synthesis of the two series of bitopic ligands, 12-Cn and 13-Cn, and their pharmacological investigation at the M\(_1\), M\(_2\), M\(_4\), and M\(_5\) FRET-based receptor sensors. The hybrids were prepared by merging the pharmacophoric moieties of the M\(_1\)/M\(_4\)-preferring orthosteric agonist Xanomeline 10 and the M\(_1\)-selective positive allosteric modulator 77-LH-28-1 (1-[3-(4-butyl-1-piperidinyl)propyl]-3,4-dihydro-2(1H)-quinolinone) 11. The two pharmacophores were connected through alkylene chains of different lengths (C3, C5, C7, and C9). Analyzing the FRET responses, the tertiary amine compounds 12-C5, 12-C7, and 12-C9 evidenced a selective activation of M\(_1\) mAChRs, while the methyl tetrahydropyridinium salts 13-C5, 13-C7, and 13-C9 showed a degree of selectivity for M\(_1\) and M\(_4\) mAChRs. Moreover, whereas hybrids 12-Cn showed an almost linear response at the M\(_1\) subtype, hybrids 13-Cn evidenced a bell-shaped activation response. This different activation pattern suggests that the positive charge anchoring the compound 13-Cn to the orthosteric site ensues a degree of receptor activation depending on the linker length, which induces a graded conformational interference with the binding pocket closure. These bitopic derivatives represent novel pharmacological tools for a better understanding of ligand-receptor interactions at a molecular level.}, language = {en} } @article{SchmidtHolzgrabe2023, author = {Schmidt, Sebastian and Holzgrabe, Ulrike}, title = {Method development, optimization, and validation of the separation of ketamine enantiomers by capillary electrophoresis using design of experiments}, series = {Chromatographia}, volume = {86}, journal = {Chromatographia}, number = {1}, issn = {0009-5893}, doi = {10.1007/s10337-022-04229-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324713}, pages = {87-95}, year = {2023}, abstract = {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\%.}, language = {en} } @article{TriyasmonoSchollmayerSchmitzetal.2023, author = {Triyasmono, Liling and Schollmayer, Curd and Schmitz, Jens and Hovah, Emilie and Lombo, Cristian and Schmidt, Sebastian and Holzgrabe, Ulrike}, title = {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}, series = {Food Analytical Methods}, volume = {16}, journal = {Food Analytical Methods}, number = {1}, issn = {1936-9751}, doi = {10.1007/s12161-022-02401-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324728}, pages = {155-167}, year = {2023}, abstract = {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.}, language = {en} }