Showing papers by "Ulrike Holzgrabe published in 1997"
65 citations
TL;DR: In this article, the effect of acetylation of β-cyclodextrin (CD) on the chiral discrimination of a series of phenethylamines has been investigated using capillary electrophoresis and nuclear magnetic resonance (NMR) spectroscopy.
42 citations
TL;DR: In this article, NMR spectra of the single enantiomers of ephedrine and N-methylephedrine in the presence of all three cyclodextrins gave information about the parts of the ligands which interact differently with the host molecules and may be responsible for chiral discrimination.
39 citations
Journal Article•
10 citations
Journal Article•
10 citations
TL;DR: Almost flat hydrophobic lateral moieties appear to be pivotal for high allosteric potency, suggesting a hydrophilic interaction of these parts of the molecule with the [3H]NMS occupied receptor protein.
8 citations
Journal Article•
TL;DR: Pyridinium aldoxime turned out to be rather stable, whereas the oxime ether and cyano derivatives convert to the pyridone at high pH-values and high temperature, and the mechanism of degradation is discussed.
Abstract: Mono- and bisbenzyloxime ethers of the bispyridinium derivative TMB-4 (UNO, DUO) are potent allosteric modulators of the muscarinic receptor attracting clinical interest in case of organophosphate poisoning. In order to work out the stability of these compounds oximes, different oxime ethers and potential degradation products were synthesized and UV- and NMR-spectroscopically characterized. The process of degradation of all compounds was observed under stress conditions at varying pH-values and different temperatures by means of time-dependent NMR- und UV-measurements. The pyridinium aldoxime turned out to be rather stable, whereas the oxime ether and cyano derivatives convert to the pyridone at high pH-values and high temperature. The mechanism of degradation is discussed.
1 citations
TL;DR: In this article, the authors proposed a hypothesis for the common pharmacophore and the corresponding active conformations, seven flexible compounds in a data set were individually aligned onto the most active and, additionally, rigid alcuronium molecule using a torsional angle flexible fit.
Abstract: Structurally dissimilar compounds such as alcuronium and the newly synthesized substances derived from the bisbenzyl ether TMB4 and from hexamethonium stabilize antagonist binding to M2-cholinoceptors which is indicative of an allosteric action. In order to propose a hypothesis for the common pharmacophore and the corresponding active conformations, seven flexible compounds in a data set were individually aligned onto the most active and, additionally, rigid alcuronium molecule using a torsional angle flexible fit. An S-shape conformation was found to be a plausible general active conformation. In a subsequent molecular shape analysis the overlap and the nonoverlap steric volumes, RMS alignment as well as electrostatic field potentials were employed as possible structure−activity correlation descriptors. The corresponding 3D-QSAR formulation exhibits a correlation between allosteric modulation potency and the nonoverlap steric volume as well as the proton and oxygen anion probe electrostatic field potenti...
1 citations