Extensive chromatographic purification of the alkaloid fraction of Aconitum vulparia Rchb. led to the isolation of a new norditerpene alkaloid, vulparine (1), besides the known compounds septentriodine (2), finetiadine (3), anthranoyllycoctonine (4), Af-methyl-N-deethyllycoctonine (5) and delectinine (6). The structure of the new compound was determined by means of HRMS, ID and 2D NMR spectroscopy. Detailed NMR studies, including 1H-1H COSY, NOESY, HSQC and HMBC experiments, resulted in complete and unambiguous 1H chemical shift assignments for 2 and 6, and revision of some 13C NMR data. Compounds 1-4 were evaluated for their cytotoxic activities, and 1, 3 and 4 were found to exhibit marginal cell growth inhibitory activity against breast adenocarcinoma (MCF-7) and cervix adenocarcinoma (HeLa) cells. © 2007 Verlag der Zeitschrift für Naturforschung.