Complete¹H and¹³C NMR Chemical Shift Assignments for Some Pentacyclic Oxindole Alkaloids

Abstract

Absaact:The complete analysis of the l H and 13C N M R has been performed for four pentacyclic oxindole alkaloids: mitraphylline, isomitraphylline, speciophylline and pteropodine. The total assignment of the l H N M R parameters was achieved from combined evaluation of homonuclear shift correlation and J-resolved diagrams, while DEPT spectra and selective decoupling experiments provided all carbon chemical shifts.

Influence of Auxins and Sucrose in Monoterpenoid Oxindole Alkaloid Production by Uncaria tomentosa Cell Suspension Cultures

“…Tetramethylsilane was employed as the internal reference. The NMR spectral data were in full agreement with those described in the literature (29)(30)(31). On the other hand, pteropodine (isolated from U. tomentosa, g85%), ajmalicine hydrochloride (Fluka, g98%), and tryptamine (Sigma, 99+%) were used as the standard compounds to determine the calibration curves for MOA, MIA, and tryptamine alkaloids (TA), respectively.…”

“…However, characterization and quantification of alkaloids produced by U. tomentosa cell cultures require obtaining reference substances, some of which are noncommercial materials, as well as developing analytical methodologies suitable for very small amounts of the alkaloids. The standard substances for the three major pentacyclic MOA produced by U. tomentosa;pteropodine (1), isopteropodine (2), and mitraphylline (3) (Figure 1);were isolated from commercial stem bark of this species and their identities were confirmed by 1 H NMR in comparison with the published spectral data (29)(30)(31). HPLC analysis of the stem bark extract of U. tomentosa obtained in the present work is shown in Figure 3a.…”

Identification and quantification of components in extracts of Uncaria tomentosa by HPLC‐ES/MS

“…In order to optimise the extraction method and HPLC conditions for the determination of these alkaloids, a preliminary HPLC-UV analysis was carried out on a fraction obtained by liquid-liquid extraction of a commercial extract. The same alkaloid fraction was also used in a semi-preparative HPLC step to isolate pure standards of the alkaloids for later quantitative analyses: such compounds were identified by 1 H-NMR by comparison with data reported in literature (Toure et al, 1992;Seki et al, 1993).…”

HPLC Analysis of Oxindole Alkaloids in Uncaria Tomentosa: Sample Preparation and Analysis Optimisation by Factorial Design

“…Potassium dihydrogen phosphate was purchased from Merck (Germany) and Polyamide 6 from Macherey-Nagel (Germany). Mitraphylline was isolated and purified by column chromatography on silica-gel (Shellard et al, 1967); ppectrometric analysis data (MS, 1 H-and 13 C-NMR) were compatible with its structure and literature data (Toure et al, 1992).…”

“…Detection and quantitation limits (LOD and LOQ respectively) were calculated according to the equations LOD = 3.3σ/S and (0), cubic (−1, 1), axial (−α, α); n = 5 at the centre. (Toure et al, 1992). Appropriate dilutions were then prepared and analysed in order to confirm those limits.…”