NMR‐spektroskopische Untersuchungen an acetylierten Digitalis‐Glykosiden

Abstract

Digitalis‐Glykoside können am Genin und (oder) an den Zuckerresten verestert sein. Weil mit den bisherigen analytischen und präparativen Methoden die Stellung der Acetylgruppen nur sehr mühevoll festzulegen war, wurde versucht, dieses Problem mit Hilfe der NMR‐Spektroskopie einfacher zu lösen: Von je 31 bei Gitoxin und Digoxin möglichen Acetaten lassen sich jetzt 15 genau, die übrigen bis auf die Stellung des Acetyls an den „inneren”︁ Digitoxosen festlegen. Beim Digitoxin lassen sich von 15 möglichen Acetaten 7 genau, die übrigen mit der gleichen Einschränkung bestimmen.

Improvement of the Oral Bioavailability of Digitalis Glycosides by CyclodextrinComplexation

“…20. These data indicate that 1:4 complex formation of digoxin with y-cyclodextrin predominate beyond the plateau region,…”

“…Table I1 summarizes a typical example of the effects of cyclodextrins on some 'H-chemical shifts (18-methyl and 19-methyl) of digoxin (20). Table I1 summarizes a typical example of the effects of cyclodextrins on some 'H-chemical shifts (18-methyl and 19-methyl) of digoxin (20).…”

Profiling and structural analysis of cardenolides in two species of Digitalis using liquid chromatography coupled with high-resolution mass spectrometry

“…The rest of the cardenolides detected belonged to the level 2b or 3, putatively characterized compounds as the spectra of these compounds are not found in the available spectral libraries such as Metlin and Global Natural Product Social Molecular Networking (GNPS) [26,27]. Nevertheless, the cardenolides observed were more than likely to be correctly annotated because 1, they were all identified in the respective species of Digitalis previously and were validated by methods including NMR [ [7,22,[28][29][30][31][32]; 2, HRMS enabled definite determination of formula for both precursor and product ions; 3, no purpurea glycosides were identified in D. lanata and no lanatosides were detected in D. purpurea, validating the specificity of the method; 4. the elution sequence of cardenolides on a C18 column highly resembled preceding reports [7]. For D. lanata, 17 out of 59 cardenolides previously identified by HPLC were confirmed and structurally annotated in our method.…”

Spectral Analysis of the Configuration and Solution Conformation of Dihydrodigoxigenin Epimers

“…2. Advantage was taken of the fact that the tertiary 14-hydroxyl group does not form esters (23). Thus, esterification with 3,5-dinitrobenzoyl chloride at the 3 and 12 positions of I yields a derivative that should have the added aromatic moiety at the 12 position sufficiently close to the C21 protons in the R epimer ( Fig.…”