The epigeal part of Aconitum talassicum M. Pop. has yielded, in addition to five alkaloids known previously, kobusine, pseudokobusine, and the new alkaloid actaline. The structure of the latter has been established on the basis of an x-ray structural analysis. Actaline is the first C20 diterpene alkaloid with a lycoctonine skeleton. © 1989 Plenum Publishing Corporation.