The dynamics of the accumulation of alkaloids in the epigeal part of Aconitum karakolicum according to vegetation periods has been studied. It has been established that the highest content of alkaloids is found in the early period. On separating the combined alkaloids, the aporphine alkaloid isoboldine has been isolated from this plant for the first time and a new base has been obtained - napelline N-oxide, the structure of which has been shown on the basis of the results of a study of spectral characteristics and direct transition to napelline. © 1980 Plenum Publishing Corporation.