Pyrrolizidine alkaloids and unusual millingtojanine A-B from Jacobaea vulgaris (syn. Senecio jacobaea L.)

Abstract

Four undescribed pyrrolizidine alkaloids (seneciojanine A-D), two enantiomeric pairs of unusual alkaloids (millingtojanine A-B) with a unique tricyclic core, and nine known pyrrolizidine alkaloids were isolated from whole plant extracts of Jacobaea vulgaris Gaertn. The structures of the undescribed compounds were established by extensive spectroscopic and spectrometric analyses and comparison of theoretical and experimental ECD data. Several of the structures were also confirmed by X-ray diffraction analysis. Seneciojanine A-D possess a rare natural necine moiety with an α,β-unsaturated carbonyl group located at C-3 and a hydroxyl substituent at C-8.