Two new diterpenoid alkaloids from the roots of Aconitum nagarum and their cytotoxic activity

A chemical investigation on the roots of Aconitum nagarum afforded two undescribed C-19-diterpenoid alkaloids nagarumines D and E (1 and 2). The structures of the new compounds were elucidated by spectral methods such as 1D and 2D (H-1-H-1 COSY, HMQC, and HMBC) NMR spectroscopy, as well as HR-ESI-MS. The two isolated alkaloids were tested in vitro for cytotoxic activity against five gastric tumor cell lines. Consequently, compound 2 exhibited some cytotoxicities against several human cancer cell lines with IC50 value less than 20.0 mu M.