Structural studies of digitoxin and related cardenolides by two-dimensional NMR

Abstract

. J. Chem. 68, 272 (1990). The 'H and I3C NMR spectra of the cardenolides digitoxigenin, digoxigenin, digitoxin, and mono-and bis-digitoxigenin digitoxosides have been c6mpletely assigned by two-dimensional NMR spectroscopy. The techniques used include phasesensitive COSY, multiple relay COSY, and carbon-proton correlation (HETCOR and HMQC) spectra. Various aspects of the solution conformation of the steroid moiety of digitoxin and digoxigenin could be determined from coupling constants and NOE difference experiments and they are indicative of an all-chair conformation. The carbohydrate rings in digitoxin and the monoand bis-digitoxigenin digitoxosides are also in the chair conformation.

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.…”

Na+/K+-ATPase-Targeted Cytotoxicity of (+)-Digoxin and Several Semisynthetic Derivatives

“…Compound 5 was assigned as the aglycone of (+)-digoxin ( 1 ) by comparing its NMR spectroscopic data with those of 1 , from which the NMR resonances assigned for the saccharide moiety of 1 were found to be absent in 5 (Table and Tables S1 and S2, Supporting Information). This was supported by its positive-ion HRESIMS data at m / z 413.2336, 390 Da (C 18 H 30 O 9 ) less than 1 . A sodium adduct ion at m / z 395.2211 [18 Da (H 2 O) less than 5 ] for a molecular formula of C 23 H 32 O 4 Na + observed for 6 indicated that this compound is a dehydrated analogue of 5 , as inferred from its NMR resonances at δ C 128.13 for C-8 and at δ C 131.57 for C-9 but not at δ C 40.51 and δ C 31.50 for the respective carbons of 5 .…”

“…Compound 5 was assigned as the aglycone of (+)-digoxin (1) by comparing its NMR spectroscopic data with those of 1, from which the NMR resonances assigned for the saccharide moiety of 1 were found to be absent in 5 (Table 1 and Tables S1 and S2, Supporting Information). 34 S1 and S2, Supporting Information). A plausible mechanism for the generation of 6 from 1 could involve an acid-mediated hydrolysis of 1 to form 5 and a 1,2-hydride shift concurrent with hydration of 5 (Scheme 3).…”

A new selective population transfer experiment using a double pulsed field gradient spin‐echo

“…2(b)], 10 which was chosen as an example to illustrate the usefulness of the DPFGSE-SPT technique. In steroidal -(e) demonstrate the change in the spectrum on the DPFGSE-SPT irradiation; the downward signal of the 3 0 , 3 00 -and upward signal of the 3 000 -H signals was irradiated.…”