Norditerpenoid alkaloids from Consolida orientalis and complete 1H and 13C NMR signal assignments of some lycoctonine-type alkaloids

A new norditerpene alkaloid was isolated, 18-demethylpubescenine (1), in addition to four known compounds, 14-demethyltuguaconitine (2), takaosamine (3), gigactonine (4), and delcosine (5), from fresh, whole plants of Consolida orientalis. The structure of 1 was established by spectroscopic methods, including various 2D NMR techniques and HRESIMS. As a result of a detailed NMR study, complete 1H NMR chemical shift assignments for alkaloids 1-5 are presented herein, and some 13C NMR signal assignments for 2-4 have been revised.