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 - 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 - Cecil, Alexander A1 - Rikanovic, Carina A1 - Ohlsen, Knut A1 - Liang, Chunguang A1 - Bernhardt, Jorg A1 - Oelschlaeger, Tobias A. A1 - Gulder, Tanja A1 - Bringmann, Gerd A1 - Holzgrabe, Ulrike A1 - Unger, Matthias A1 - Dandekar, Thomas T1 - Modeling antibiotic and cytotoxic effects of the dimeric isoquinoline IQ-143 on metabolism and its regulation in Staphylococcus aureus, Staphylococcus epidermidis and human cells N2 - Background: Xenobiotics represent an environmental stress and as such are a source for antibiotics, including the isoquinoline (IQ) compound IQ-143. Here, we demonstrate the utility of complementary analysis of both host and pathogen datasets in assessing bacterial adaptation to IQ-143, a synthetic analog of the novel type N,C-coupled naphthyl-isoquinoline alkaloid ancisheynine. Results: Metabolite measurements, gene expression data and functional assays were combined with metabolic modeling to assess the effects of IQ-143 on Staphylococcus aureus, Staphylococcus epidermidis and human cell lines, as a potential paradigm for novel antibiotics. Genome annotation and PCR validation identified novel enzymes in the primary metabolism of staphylococci. Gene expression response analysis and metabolic modeling demonstrated the adaptation of enzymes to IQ-143, including those not affected by significant gene expression changes. At lower concentrations, IQ-143 was bacteriostatic, and at higher concentrations bactericidal, while the analysis suggested that the mode of action was a direct interference in nucleotide and energy metabolism. Experiments in human cell lines supported the conclusions from pathway modeling and found that IQ-143 had low cytotoxicity. Conclusions: The data suggest that IQ-143 is a promising lead compound for antibiotic therapy against staphylococci. The combination of gene expression and metabolite analyses with in silico modeling of metabolite pathways allowed us to study metabolic adaptations in detail and can be used for the evaluation of metabolic effects of other xenobiotics. KW - Staphylococcus aureus Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68802 ER - TY - JOUR A1 - Masic, Anita A1 - Valencia Hernandez, Ana Maria A1 - Hazra, Sudipta A1 - Glaser, Jan A1 - Holzgrabe, Ulrike A1 - Hazra, Banasri A1 - Schurigt, Uta T1 - Cinnamic Acid Bornyl Ester Derivatives from Valeriana wallichii Exhibit Antileishmanial In Vivo Activity in Leishmania major-Infected BALB/c Mice JF - PLoS One N2 - Human leishmaniasis covers a broad spectrum of clinical manifestations ranging from self-healing cutaneous leishmaniasis to severe and lethal visceral leishmaniasis caused among other species by Leishmania major or Leishmania donovani, respectively. Some drug candidates are in clinical trials to substitute current therapies, which are facing emerging drug-resistance accompanied with serious side effects. Here, two cinnamic acid bornyl ester derivatives (1 and 2) were assessed for their antileishmanial activity. Good selectivity and antileishmanial activity of bornyl 3-phenylpropanoate (2) in vitro prompted the antileishmanial assessment in vivo. For this purpose, BALB/c mice were infected with Leishmania major promastigotes and treated with three doses of 50 mg/kg/day of compound 2. The treatment prevented the characteristic swelling at the site of infection and correlated with reduced parasite burden. Transmitted light microscopy and transmission electron microscopy of Leishmania major promastigotes revealed that compounds 1 and 2 induce mitochondrial swelling. Subsequent studies on Leishmania major promastigotes showed the loss of mitochondrial transmembrane potential (ΔΨm) as a putative mode of action. As the cinnamic acid bornyl ester derivatives 1 and 2 had exhibited antileishmanial activity in vitro, and compound 2 in Leishmania major-infected BALB/c mice in vivo, they can be regarded as possible lead structures for the development of new antileishmanial therapeutic approaches. KW - leishmania major KW - promastigotes KW - apoptosis KW - mitochondria KW - parasitic diseases KW - leishmania KW - leishmaniasis KW - mouse models Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125354 VL - 10 IS - 11 ER - TY - JOUR A1 - Glaser, Jan A1 - Schurigt, Uta A1 - Suzuki, Brian M. A1 - Caffrey, Connor R. A1 - Holzgrabe, Ulrike T1 - Anti-Schistosomal Activity of Cinnamic Acid Esters: Eugenyl JF - Molecules N2 - Bornyl caffeate (1) was previously isolated by us from Valeriana (V.) wallichii rhizomes and identified as an anti-leishmanial substance. Here, we screened a small compound library of synthesized derivatives 1–30 for activity against schistosomula of Schistosoma (S.) mansoni. Compound 1 did not show any anti-schistosomal activity. However, strong phenotypic changes, including the formation of vacuoles, degeneration and death were observed after in vitro treatment with compounds 23 (thymyl cinnamate) and 27 (eugenyl cinnamate). Electron microscopy analysis of the induced vacuoles in the dying parasites suggests that 23 and 27 interfere with autophagy. KW - thymyl cinnamate KW - vacuoles KW - autophagy KW - anti-schistosomal activity KW - schistosoma KW - schistosomula KW - parasite KW - eugenyl cinnamate Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125712 VL - 20 ER - TY - JOUR A1 - Glaser, Jan A1 - Schultheis, Martina A1 - Moll, Heidrun A1 - Hazra, Banasri A1 - Holzgrabe, Ulrike T1 - Antileishmanial and Cytotoxic Compounds from Valeriana wallichii and Identification of a Novel Nepetolactone Derivative JF - Molecules N2 - The chloroform extract of Valeriana wallichii (V. wallichii) rhizomes was investigated to elucidate the structures responsible for reported antileishmanial activity. Besides bornyl caffeate (1, already been reported by us previously), bioassay-guided fractionation resulted in two additional cinnamic acid derivatives 2–3 with moderate leishmanicidal activity. The structure of a novel nepetolactone derivative 4 having a cinnamic acid moiety was elucidated by means of spectral analysis. To the best of our knowledge villoside aglycone (5) was isolated from this plant for the first time. The bioassay-guided fractionation yielded two new (compounds 6–7) and two known valtrates (compounds 8–9) with leishmanicidal potential against Leishmania major (L. major) promastigotes. In addition, β-bisabolol (10), α-kessyl alcohol (11), valeranone (12), bornyl isovalerate (13) and linarin-2-O-methylbutyrate (14) were identified. This is the first report on the isolation of 4'-demethylpodophyllotoxin (15), podophyllotoxin (16) and pinoresinol (17) in V. wallichii. In total thirteen known and four new compounds were identified from the extract and their cytotoxic and antileishmanial properties were evaluated. KW - novel nepetolactone derivative KW - cytotoxicity KW - antileishmanial KW - V. wallichii KW - podophyllotoxin KW - valtrates Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125320 VL - 20 IS - 4 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 - TY - JOUR A1 - Hartung, Andreas A1 - Seufert, Florian A1 - Berges, Carsten A1 - Gessner, Viktoria H. A1 - Holzgrabe, Ulrike T1 - One-Pot Ugi/Aza-Michael Synthesis of Highly Substituted 2,5-Diketopiperazines with Anti-Proliferative Properties JF - Molecules N2 - The well-known Ugi reaction of aldehydes with amines, carboxylic acids and isocyanides leads to the formation of acyclic alpha-acylaminocarboxamides. Replacement of the carboxylic acid derivatives with beta-acyl substituted acrylic acids gives access to highly substituted 2,5-diketopiperazines in one single reaction-step without additives or complex reaction procedures. The obtained diketopiperazines show anti-proliferative effects on activated T cells and represent therefore potential candidates for targeting unwanted T cell-mediated immune responses. KW - multicomponent Ugi-type reaction KW - intramolecular Michael addition KW - strategy KW - derivates KW - diketopiperazines KW - chemistry KW - T cell KW - 2,5-diketopiperazines KW - anti-proliferative effects Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130423 VL - 17 IS - 12 ER - TY - JOUR A1 - Glaser, Jan A1 - Schultheis, Martina A1 - Hazra, Sudipta A1 - Hazra, Banazri A1 - Moll, Heidrun A1 - Schurigt, Uta A1 - Holzgrabe, Ulrike T1 - Antileishmanial Lead Structures from Nature: Analysis of Structure-Activity Relationships of a Compound Library Derived from Caffeic Acid Bornyl Ester N2 - Bioassay-guided fractionation of a chloroform extract of Valeriana wallichii (V. wallichii) rhizomes lead to the isolation and identification of caffeic acid bornyl ester (1) as the active component against Leishmania major (L. major) promastigotes (IC50 = 48.8 µM). To investigate the structure-activity relationship (SAR), a library of compounds based on 1 was synthesized and tested in vitro against L. major and L. donovani promastigotes, and L. major amastigotes. Cytotoxicity was determined using a murine J774.1 cell line and bone marrow derived macrophages (BMDM). Some compounds showed antileishmanial activity in the concentration range of pentamidine and miltefosine which are the standard drugs in use. In the L. major amastigote assay compounds 15, 19 and 20 showed good activity with relatively low cytotoxicity against BMDM, resulting in acceptable selectivity indices. Molecules with adjacent phenolic hydroxyl groups exhibited elevated cytotoxicity against murine cell lines J774.1 and BMDM. The Michael system seems not to be essential for antileishmanial activity. Based on the results compound 27 can be regarded as new lead structure for further structure optimization KW - Valeriana wallichii KW - leishmaniasis KW - caffeic acid bornyl ester KW - structure-activity relationship Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-112835 ER - TY - JOUR A1 - Güntzel, Paul A1 - Schilling, Klaus A1 - Hanio, Simon A1 - Schlauersbach, Jonas A1 - Schollmayer, Curd A1 - Meinel, Lorenz A1 - Holzgrabe, Ulrike T1 - Bioinspired Ion Pairs Transforming Papaverine into a Protic Ionic Liquid and Salts JF - ACS Omega N2 - Microbial, mammalian, and plant cells produce and contain secondary metabolites, which typically are soluble in water to prevent cell damage by crystallization. The formation of ion pairs, for example, with carboxylic acids or mineral acids, is a natural blueprint to maintain basic metabolites in solution. Here, we aim at showing whether the mostly large carboxylates form soluble protic ionic liquids (PILs) with the basic natural product papaverine resulting in enhanced aqueous solubility. The obtained PILs were characterized by H-1-N-15 HMBC nuclear magnetic resonance (NMR) and in the solid state using X-ray powder diffraction, differential scanning calorimetry, and dissolution measurements. Furthermore, their supramolecular pattern in aqueous solution was studied by means of potentiometric and photometrical solubility, NMR aggregation assay, dynamic light scattering, zeta potential, and viscosity measurements. Thereby, we identified the naturally occurring carboxylic acids, citric acid, malic acid, and tartaric acid, as being appropriate counterions for papaverine and which will facilitate the formation of PILs with their beneficial characteristics, like the improved dissolution rate and enhanced apparent solubility. KW - solubility KW - transport KW - strategy KW - drugs KW - forms KW - acids Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230265 VL - 5 IS - 30 ER - TY - JOUR A1 - Leistner, Adrian A1 - Holzgrabe, Ulrike T1 - Impurity Profiling of Baclofen Using Gradient HPLC–UV Method JF - Chromatographia N2 - The GABA\(_{B}\) receptor agonist baclofen is a medication commonly used for the treatment of muscle spasticity. It is an amino acid and related to the neurotransmitter GABA. In this study, we developed a new, gradient high-performance liquid chromatography (HPLC) method for the impurity assessment of baclofen, which is appropriate for pharmacopoeial purposes. Since the impurities related to the synthesis pathway are acids, zwitterionic, or neutral, the method development is challenging. However, the separation of all components was achieved on a C18 stationary phase using a water–acetonitrile–trifluoroacetic acid gradient. A limit of detection (LOD) of at least 0.02% was registered for all specified impurities. Additionally, CAD detection was performed to detect potential impurities lacking off a chromophore. The baclofen batches analyzed are far more pure than expected. All impurities were found below the specification limit, and thus, they can be regarded as unspecified. Moreover, the required runtime could be significantly reduced compared to the current USP or Ph. Eur. method. KW - GABA\(_{B}\) KW - impurity profiling KW - baclofen KW - gradient HPLC–UV KW - CAD detection KW - pharmaceutical analysis Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-268921 SN - 1612-1112 VL - 84 IS - 10 ER - TY - JOUR A1 - Matera, Carlo A1 - Kauk, Michael A1 - Cirillo, Davide A1 - Maspero, Marco A1 - Papotto, Claudio A1 - Volpato, Daniela A1 - Holzgrabe, Ulrike A1 - De Amici, Marco A1 - Hoffmann, Carsten A1 - Dallanoce, Clelia T1 - Novel Xanomeline-containing bitopic ligands of muscarinic acetylcholine receptors: design, synthesis and FRET investigation JF - Molecules N2 - 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. KW - muscarinic acetylcholine receptors KW - Xanomeline KW - 77-LH-28-1 KW - bitopic hybrid ligands KW - synthesis KW - fluorescence resonance energy transfer Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-311249 SN - 1420-3049 VL - 28 IS - 5 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 - 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 - 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 - El-Hossary, Ebaa M. A1 - Abdel-Halim, Mohammad A1 - Ibrahim, Eslam S. A1 - Pimentel-Elardo, Sheila Marie A1 - Nodwell, Justin R. A1 - Handoussa, Heba A1 - Abdelwahab, Miada F. A1 - Holzgrabe, Ulrike A1 - Abdelmohsen, Usama Ramadan T1 - Natural Products Repertoire of the Red Sea JF - Marine Drugs N2 - Marine natural products have achieved great success as an important source of new lead compounds for drug discovery. The Red Sea provides enormous diversity on the biological scale in all domains of life including micro- and macro-organisms. In this review, which covers the literature to the end of 2019, we summarize the diversity of bioactive secondary metabolites derived from Red Sea micro- and macro-organisms, and discuss their biological potential whenever applicable. Moreover, the diversity of the Red Sea organisms is highlighted as well as their genomic potential. This review is a comprehensive study that compares the natural products recovered from the Red Sea in terms of ecological role and pharmacological activities. KW - Red Sea KW - marine natural products KW - marine organisms KW - biodiversity KW - marine metagenomics KW - bioactivity Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-213110 SN - 1660-3397 VL - 18 IS - 9 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 - 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 - 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 - Bulitta, Jürgen B. A1 - Jiao, Yuanyuan A1 - Landersdorfer, Cornelia B. A1 - Sutaria, Dhruvitkumar S. A1 - Tao, Xun A1 - Shin, Eunjeong A1 - Höhl, Rainer A1 - Holzgrabe, Ulrike A1 - Stephan, Ulrich A1 - Sörgel, Fritz T1 - Comparable Bioavailability and Disposition of Pefloxacin in Patients with Cystic Fibrosis and Healthy Volunteers Assessed via Population Pharmacokinetics JF - Pharmaceutics N2 - Quinolone antibiotics present an attractive oral treatment option in patients with cystic fibrosis (CF). Prior studies have reported comparable clearances and volumes of distribution in patients with CF and healthy volunteers for primarily renally cleared quinolones. We aimed to provide the first pharmacokinetic comparison for pefloxacin as a predominantly nonrenally cleared quinolone and its two metabolites between both subject groups. Eight patients with CF (fat-free mass [FFM]: 36.3 ± 6.9 kg, average ± SD) and ten healthy volunteers (FFM: 51.7 ± 9.9 kg) received 400 mg pefloxacin as a 30 min intravenous infusion and orally in a randomized, two-way crossover study. All plasma and urine data were simultaneously modelled. Bioavailability was complete in both subject groups. Pefloxacin excretion into urine was approximately 74% higher in patients with CF compared to that in healthy volunteers, whereas the urinary excretion of metabolites was only slightly higher in patients with CF. After accounting for body size and composition via allometric scaling by FFM, pharmacokinetic parameter estimates in patients with CF divided by those in healthy volunteers were 0.912 for total clearance, 0.861 for nonrenal clearance, 1.53 for renal clearance, and 0.916 for volume of distribution. Nonrenal clearance accounted for approximately 90% of total pefloxacin clearance. Overall, bioavailability and disposition were comparable between both subject groups. KW - cystic fibrosis patients KW - healthy volunteers KW - fluoroquinolone KW - pefloxacin KW - absolute bioavailability KW - population pharmacokinetics 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-197221 SN - 1999-4923 VL - 11 IS - 7 ER -