Investigation of the alkaloidal constituents of the roots of Aconitum nasutum led to the isolation and identification of a new diterpenoid alkaloid designated as trabzonine (1). Three known norditerpenoid alkaloids, lappaconitine (2), lycoctonine (3) and gigactonine (4), and two known diterpenoid alkaloids pseudokobusine (5) and septatisine (6) were also isolated. The structures of 1 and 5 were established by detailed analyses of 1H and 13C NMR data. The structure and absolute stereochemistry of pseudokobusine (5) was determined by an X-Ray crystal structure determination
