Voacafrines A-N, aspidosperma-type monoterpenoid indole alkaloids from Voacanga africana with AChE inhibitory activity

Investigation of Small-Molecule Constituents in Voacanga africana Seeds and Mapping of Their Spatial Distributions Using Laser Ablation Direct Analysis in Real-Time Imaging–Mass Spectrometry (LADI-MS)

“…Iboluteine, tabersonine, voacafrine M, (−)-β-yohimbine, voacafrine N, jerantinine B, brassicasterol, stigmasterol, DL-α-tocopherol, vobtusine, voacaline, and 3-ethylpyridine have all been isolated from V. africana seeds in previous work, ,,,,,,, and their respective protonated monoisotopic masses were detected. Li et al identified a compound with the formula C 21 H 22 N 2 O 5 in seeds (Table entry 16), and its corresponding formula in protonated form was observed here by DART-HRMS.…”

“…The protonated forms of the formulas associated with the isomers 3-oxotabersonine and perakine (C 21 H 22 N 2 O 3 ), both of which have been isolated from V. africana seeds, ,, were also detected. Through our GC-MS analyses (see Table , column 5), we identified the formula C 21 H 24 N 2 O 3 to correspond to the compounds vobasine, akuammidine, polyneuridine, and Δ 14 -vincamine.…”

“…For example, from an ethanol extract, Li et al observed 3-oxotabersonine, 3α-acetonylvoafrine B, lochnericine, 17,18-dehydrovincamine (Δ 14 -vincamine), tabersonine, and a new compound with the formula C 21 H 22 N 2 O 5 , which were characterized by NMR spectroscopy . On the other hand, Zhao et al reported an entirely different set of detected molecules (i.e., voacafrines A–N, voafrine A, voafrine B, 3-oxotabersonine, 3α-acetonyltabersonine, 3α-acetonylvoafrine B, 3-oxovoafrine B, and melodinine S), which were detected and characterized using a methanol extraction protocol, column chromatography, and NMR spectroscopy . Given that in these studies, the approaches taken to analyze the seeds were distinct, the observation of a different range of molecules in each case could be a consequence of the differences in experimental methods, which may have favored detection of some compounds over others depending on the protocol used.…”

“…africana seeds . These compounds have been isolated using various extraction protocols, ,− in addition to column chromatography ,− and thin layer chromatography (TLC), , and structurally characterized by 1 H nuclear magnetic resonance (NMR) spectroscopy, ,,, 13 C NMR spectroscopy, ,,− 1 H- 1 H COSY, infrared (IR) spectroscopy, high-resolution mass spectrometry ,, and gas chromatography–mass spectrometry (GC-MS). , Once the presence within seeds of compounds of interest is established, a next step would be to develop a method by which to isolate them. To optimize the isolation protocol for the extraction and purification of relevant compounds from seeds, it would be extremely helpful if the spatial distributions within the seed tissue can be determined beforehand, as this would reduce the expense, waste and overuse of solvent, save time, and enable institution of pretreatment steps to avoid the processing of tissues which do not contain the material of interest.…”

Voatriafricanines A and B, Trimeric Vobasine-Aspidosperma-Aspidosperma Alkaloids from Voacanga africana

“…As part of our research program directed toward the streamlined hypothesis-driven reinvestigation of previously investigated plants, − we endeavored toward the phytochemical study of Voacanga africana Stapf (Apocynaceae). This plant has been the subject of extensive phytochemical isolation efforts since 1959, resulting in the description of a wealth of monomers and dimers belonging to the aspidosperma- and iboga-type alkaloids . Economically, with over 1600 tons of seeds exported annually from Ghana and Ivory Coast, V. africana is an important source of additional income for harvesters and exporters in West Africa .…”