Electrospray ionization tandem mass spectrometric study of the aconitines in the roots of aconite

Abstract

Fragmentation pathways of aconitine‐type alkaloids were investigated by electrospray ionization/ion trap multistage tandem mass spectrometry. Low‐energy collision‐induced dissociation of protonated aconitines follows a dominant first step, the elimination of the C₈‐substituent as acetic acid or fatty acid in MS² spectra. Successive losses of 1–4 CH₃OH molecules, 1–3 H₂O, CO, benzoic acid, and CH₃ or C₂H₅ (N‐substituents) are all fragmentation pathways observed in MS³ and MS⁴ spectra. By applying knowledge of these fragmentation pathways to the aconitines in the ethanolic extract of aconite roots, all the known aconitines were detected and also 23 unknown aconitine‐type alkaloids, in which the lipo‐alkaloids containing residues of 15C, 17C and 19C saturated or unsaturated fatty acids were characterized. These odd‐carbon‐number fatty acid substituents have not been reported previously. Copyright © 2002 John Wiley & Sons, Ltd.