1H-NMR Dotaz Zobrazit nápovědu
The acid-base dissociation constant (pKa) is an important physicochemical parameter of weakly acid or weakly basic pharmaceuticals, which influences solubility, absorption, distribution, metabolism and elimination of drugs. pKa of four standard β-blockers were firstly determined by capillary zone electrophoresis (CZE). Method is based on measurement of the effective electrophoretic mobility of an ionisable compound in a series of electrolyte solutions of various pHs. This dependence was fitted by a sigmoidal curve, where pKa is the value of pH in the sigmoid inflection point. Then, pKa was measured by reversed- phase high-performance liquid chromatography (RP-HPLC) using the sigmoidal dependence of the retention factor on pH of the mobile phase (methanol/phosphate buffer), where pKa is the value of pH in the sigmoid inflection point. Thirdly, determination of pKa using 1H nuclear magnetic resonance (1H NMR) was based on measurement of chemical shifts of selected protons of studied substances as a function of solution pH (methanol-d4/D2O). Values of pKa obtained for water/methanol mixtures were recalculated for water medium. Experimentally obtained values of pKa were compared with values calculated by SPARC, Marvin 5.8.2 and
- MeSH
- acidobazická rovnováha MeSH
- beta blokátory analýza chemie MeSH
- chemické techniky analytické MeSH
- chemie fyzikální MeSH
- chromatografie s reverzní fází metody využití MeSH
- elektroforéza kapilární metody využití MeSH
- magnetická rezonanční spektroskopie MeSH
- Publikační typ
- práce podpořená grantem MeSH
The liquid state NMR chemical shift of protons is a parameter frequently used to characterize host-guest complexes. Its theoretical counterpart, that is, the 1H NMR chemical shielding affected by the solvent (1H CS), may provide important insights into spatial arrangements of supramolecular systems, and it can also be reliably obtained for challenging cases of an aggregation of aromatic and antiaromatic molecules in solution. This computational analysis is performed for the complex of coronene and an antiaromatic model compound in acetonitrile by employing the GIAO-B3LYP-PCM approach combined with a saturated basis set. Predicted 1H CS values are used to generate volumetric data, whose properties are thoroughly investigated. The 1H CS isosurface, corresponding to a value of the proton chemical shift taken from a previous experimental study, is described. The presence of the 1H CS isosurface should be taken into account in deriving structural information about supramolecular hosts and their encapsulation of small molecules.
- MeSH
- acetonitrily chemie MeSH
- difrakce rentgenového záření MeSH
- izotopy uhlíku MeSH
- magnetická rezonanční spektroskopie metody MeSH
- makromolekulární látky MeSH
- nikl chemie MeSH
- normální rozdělení MeSH
- polycyklické sloučeniny chemie MeSH
- protonová magnetická rezonanční spektroskopie MeSH
- protony MeSH
- rozpouštědla chemie MeSH
- železo chemie MeSH
- Publikační typ
- časopisecké články MeSH
Most recently a renewed interest in several areas has arisen in factors governing the 1H NMR chemical shift (1H CS) of protons in aromatic systems. Therefore, it is important to describe how 1H CS values are affected by π-stacking intermolecular interactions. The parametrization of radial and angular dependences of the 1H CS is proposed, which is based on conventional gauge-independent atomic orbital (GIAO) calculations of explicit molecular fragments. Such a parametrization is exemplified for a benzene dimer with intermonomer vertical and horizontal distances which are in the range of values often found in crystals of organic compounds. Results obtained by the GIAO calculations combined with B3LYP and MP2 methods were compared, and revealed qualitatively the same trends in the 1H CS data. The parametrization was found to be quantitatively correct for the T-shaped benzene dimers, and its limitations were discussed. Parametrized 1H CS surfaces should become useful for providing additional restraints in the search of site-specific information through an analysis of structurally induced 1H CS changes.
Corylus avellana L. (Betulaceae) leaves, consumed as infusion, are used in traditional medicine, for the treatment of hemorrhoids, varicose veins, phlebitis, and edema due to their astringent, vasoprotective, and antiedema properties. In previous works we reported from the leaves of Corylus avellana cv. "Tonda di Giffoni" diarylheptanoid derivatives, a class of plant secondary metabolites with a wide variety of bioactivities. With the aim to give an interesting and economically feasible opportunity to C. avellana leaves as source of functional ingredients for pharmaceutical and cosmetic formulations, "green" extracts were prepared by employing "eco-friendly" extraction protocols as maceration, infusion and SLDE-Naviglio extraction. Metabolite profiles of the extracts were obtained by 1H NMR experiments and data were processed by multivariate statistical analysis to highlight differences in the extracts and to evidence the extracts with the highest concentrations of bioactive metabolites. Based on the NMR data, a total of 31 compounds were identified. The metabolite variation among the extracts was evaluated using Principle Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA). Furthermore, the total phenolic content of the extracts was measured by Folin-Ciocalteu colorimetric assay and the antioxidant activity of extracts was assayed by the spectrophotometric tests DPPH• and ABTS and by an in vitro test based on the evaluation of cellular reactive oxygen species production stimulated by pyocyanin.
- MeSH
- fenoly analýza farmakologie MeSH
- lidé MeSH
- líska chemie metabolismus MeSH
- listy rostlin chemie MeSH
- metabolomika metody MeSH
- nukleární magnetická rezonance biomolekulární metody MeSH
- protonová magnetická rezonanční spektroskopie metody MeSH
- pyokyanin farmakologie MeSH
- reaktivní formy kyslíku metabolismus MeSH
- rostlinné extrakty analýza chemie farmakologie MeSH
- scavengery volných radikálů analýza farmakologie MeSH
- technologie zelené chemie metody MeSH
- THP-1 buňky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The 1H chemical shielding anisotropy (CSA) is an NMR parameter that is exquisitely sensitive to the local environment of protons in crystalline systems, but it is difficult to obtain it experimentally due to the need to concomitantly suppress other anisotropic interactions in the solid-state NMR (SSNMR) pulse sequences. The SSNMR measurements of the 1H CSA are particularly challenging if the fast magic-angle-spinning (MAS) is applied. It is thus important to confront the results of both the single-crystal (SC) and fast-MAS experiments with their theoretical counterparts. Here the plane-waves (PW) DFT calculations have been carried out using two functionals in order to precisely characterize the structures and the 1H NMR chemical shielding tensors (CSTs) of the solid forms of maleic, malonic, and citric acids, and of L-histidine hydrochloride monohydrate. The level of agreement between the PW DFT and either SC or fast-MAS SSNMR 1H CSA data has been critically compared. It has been found that for the eigenvalues of the 1H CSTs provided by the fast-MAS measurements, an accuracy limit of current PW DFT predictions is about two ppm in terms of the standard deviation of the linear regression model, and sources of this error have been thoroughly discussed.
The association of pancreatic cancer with type 2 diabetes mellitus was investigated by 1H NMR metabolomic analysis of blood plasma. Concentration data of 58 metabolites enabled discrimination of pancreatic cancer (PC) patients from healthy controls (HC) and long-term type 2 diabetes mellitus (T2DM) patients. A panel of eight metabolites was proposed and successfully tested for group discrimination. Furthermore, a prediction model for the identification of at-risk individuals for future development of pancreatic cancer was built and tested on recent-onset diabetes mellitus (RODM) patients. Six of 59 RODM samples were assessed as PC with an accuracy of more than 80%. The health condition of these individuals was re-examined, and in four cases, a correlation to the prediction was found. The current health condition can be retrospectively attributed to misdiagnosed pancreatogenic diabetes or to early-stage pancreatic cancer.
- MeSH
- časná detekce nádoru MeSH
- diabetes mellitus 2. typu * diagnóza MeSH
- diabetes mellitus * MeSH
- lidé MeSH
- metabolomika MeSH
- nádory slinivky břišní * diagnóza MeSH
- protonová magnetická rezonanční spektroskopie MeSH
- retrospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Characterization of metabolites and microbiota composition from human stool provides powerful insight into the molecular phenotypic difference between subjects with normal weight and those with overweight/obesity. The aim of this study was to identify potential metabolic and bacterial signatures from stool that distinguish the overweight/obesity state in children/adolescents. Using 1H NMR spectral analysis and 16S rRNA gene profiling, the fecal metabolic profile and bacterial composition from 52 children aged 7 to 16 was evaluated. The children were classified into three groups (16 with normal-weight, 17 with overweight, 19 with obesity). The metabolomic analysis identified four metabolites that were significantly different (p < 0.05) among the study groups based on one-way ANOVA testing: arabinose, butyrate, galactose, and trimethylamine. Significantly different (p < 0.01) genus-level taxa based on edgeR differential abundance tests were genus Escherichia and Tyzzerella subgroup 3. No significant difference in alpha-diversity was detected among the three study groups, and no significant correlations were found between the significant taxa and metabolites. The findings support the hypothesis of increased energy harvest in obesity by human gut bacteria through the growing observation of increased fecal butyrate in children with overweight/obesity, as well as an increase of certain monosaccharides in the stool. Also supported is the increase of trimethylamine as an indicator of an unhealthy state.
- MeSH
- Bacteria genetika MeSH
- dítě MeSH
- feces mikrobiologie MeSH
- lidé MeSH
- metabolom MeSH
- metabolomika MeSH
- mladiství MeSH
- obezita dětí a dospívajících metabolismus mikrobiologie MeSH
- obezita metabolismus mikrobiologie MeSH
- protonová magnetická rezonanční spektroskopie MeSH
- RNA ribozomální 16S genetika MeSH
- střevní mikroflóra genetika MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
