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

Abstract

Voatriafricanines A and B (1 and 2), the first examples of vobasine-aspidosperma-aspidosperma monoterpene trisindole alkaloids, were isolated from the stem barks of Voacanga africana, guided by a molecular networking strategy. Their structures, including absolute configurations, were elucidated by spectroscopic methods and ECD calculations. Compounds 1 and 2 possess intramolecular hydrogen bonding, sufficiently robust to transfer homonuclear and heteronuclear magnetizations. Compound 1 exhibited potent antimycobacterial activity with no discernible cytotoxic activity.

Indole-Containing Natural Products 2019–2022: Isolations, Reappraisals, Syntheses, and Biological Activities

“…Compound 229 is a novel indole-linked 2,5-diketomorpholine alkaloid with an unprecedented 6/5/6/6/5 core, while compound 230 contains an indole fused with pyrrole and possesses a 6/5/5 core [ 64 ]. Compounds 231 and 232 were isolated from the bark of Voacanga africana , and they are the first monoterpene trisindole alkaloids containing a vobasine–aspidosperma–aspidosperma skeleton [ 65 ]. Similarly, compound 233 is the first methylenedioxy dibromoindole alkaloid exhibiting antiosteoporosis activity [ 66 ].…”

“…Compounds 231 and 232 showed no cytotoxicity, and only compound 231 showed weak antimycobacterial activity. Replacing the C-12 proton in compound 231 with a methoxy group as in 232 completely lost the activity [ 65 ].…”

Implementation of a MS/MS database for isoquinoline alkaloids and other annonaceous metabolites

“…In such context, molecular networking strategies have proved useful to select natural material deserving deeper chemical studies as well as to streamline the isolation of compounds of interest through a rational, hypothesis-driven workflow 21 . This provides new opportunities to focus on minor, interesting compounds from deeply-dug plant material 22 , 23 . Nevertheless, the success of this dereplicative strategy primarily depends on the availability of reference tandem mass spectra uploaded to the GNPS spectral libraries 7 .…”

Combination of Machine Learning and Empirical Computation for the Structural Validation of Trirosaline, a Natural Trimeric Monoterpene Indole Alkaloid from Catharanthus roseus

“…Despite decades of intensive phytochemical campaigns dedicated to the monoterpene indole alkaloid (MIA) content of this plant, it still represents a subject of phytochemical and biosynthesis investigations. , Here we describe the structure elucidation, a plausible biosynthetic logic, and the biological evaluation of trirosaline ( 1 ), the first example of a naturally occurring trimeric monoterpene indole alkaloid in C. roseus . So far, ten trimers have been encountered in the MIA family, namely: strychnohexamine, bousigonine B, bousangustine A, taberdivarines A and B, divaricamine A, ervadivamines A and B, as well as voatriafricanines A and B …”

“…8 So far, ten trimers have been encountered in the MIA family, namely: strychnohexamine, 9 bousigonine B, 10 bousangustine A, 11 taberdivarines A and B, 12 divaricamine A, 13 ervadivamines A and B, 14 as well as voatriafricanines A and B. 3 As a way to explore the chemical diversity of the alkaloid extract of the roots of C. roseus, UHPLC-MS profiling was performed. The cursory examination of its mass chromatogram revealed a signal standing for an unusually heavy molecule in this plant source.…”