Ibogaine and Noribogaine: Structural Analysis and Stability Studies. Use of LC‐MS to Determine Alkaloid Contents of the Root Bark of Tabernanthe Iboga

Ibogaine and noribogaine, alkaloids from the Tabernanthe iboga shrub, break down when exposed to daylight or 254 nm UV light in methanol, forming oxidation products such as ibochine, iboluteine, and their desmethoxy analogues. A possible lactam derivative also appears under UV. Analysis of root bark from one shrub using liquid chromatography-mass spectrometry detected seven alkaloids: ibochine, ibogaline, iboluteine, ibogaine, ibogamine, voacangine, and an unidentified compound at m/z 309. Ibogaine was the most abundant alkaloid, with concentrations between 1.8 and 5.93 mg/g. The peak areas of ibogaline, ibogamine, and voacangine were 11.9%, 21.5%, and 30.5% of ibogaine's, respectively.

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Abstract

Abstract The aim of this study was: i) to carry out a structural analysis of ibogaine and noribogaine, ii) to identify products formed under light exposure (daylight or 254 nm, 20°C) of the two drugs in methanolic solutions, and iii) to examine the alkaloid contents of a specimen of root bark of the Tabernanthe iboga shrub using liquid chromatography‐electrospray mass spectrometry. After daylight exposure, two oxidation products were detected: ibochine and iboluteine from ibogaine, and desmethoxyibochine and desmethoxyiboluteine from noribogaine. After exposure to 254 nm of the ibogaine solution, another compound that could possibly be the analogous lactam of iboluteine was detected. From the liquid chromatography electrospray‐mass spectrometry analysis of the root barks of a specimen of the Tabernanthe iboga shrub, seven alkaloids were detected: ibochine (m/z 325), ibogaline (m/z 341), iboluteine (m/z 327), ibogaine (m/z 311), ibogamine (m/z 281) and voacangine (m/z 369). The last compound characterized by the protonated species (M+H)+ at m/z 309 has not been identified. In all samples, ibogaine was the principal alkaloid observed; its concentration ranged from 1.8 to 5.93 mg/g. For the other indole alkaloids, the peak areas of ibogaline, ibogamine and voacangine represent 11.9, 21.5, and 30.5% of that of ibogaine, respectively.