Diterpenoid alkaloids with remarkable chemical properties and biological activities are frequently found in plants of the genera Aconitum, Delphinium, and Garrya. Accordingly, several C19-diterpenoid
alkaloid components from Delphinium elatum cv. Pacific Giant, as well as their derivatives, exhibited cytotoxic activity against lung, prostate, nasopharyngeal, and
vincristine-resistant
nasopharyngeal cancer cell lines. Four new C19-diterpenoid
alkaloids, elapacigine (1), N-deethyl-N-formylpaciline (2), N-deethyl-N-formylpacinine (3), and N-formyl-4,19-secoyunnadelphinine (4), together with 11 known C19-diterpenoid
alkaloids were isolated in a
phytochemical investigation on the seeds of D. elatum cv. Pacific Giant. Their structures were elucidated by extensive spectroscopic methods including NMR (1D and 2D), IR, and MS (HRMS). Three of the new C19-diterpenoid
alkaloids (2-4) and five of the known
diterpenoid alkaloids were evaluated for cytotoxic activity against five human tumor cell lines.