@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}
}
@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{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{GuentzelSchillingHanioetal.2020,
  author    = {G{\"u}ntzel, Paul and Schilling, Klaus and Hanio, Simon and Schlauersbach, Jonas and Schollmayer, Curd and Meinel, Lorenz and Holzgrabe, Ulrike},
  title     = {Bioinspired Ion Pairs Transforming Papaverine into a Protic Ionic Liquid and Salts},
  series = {ACS Omega},
  volume    = {5},
  journal   = {ACS Omega},
  number    = {30},
  doi       = {10.1021/acsomega.0c02630},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230265},
  pages     = {19202-19209},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}