Isolation and structure elucidation of alkaloids from the bulb of Fritillaria wabuensis

Eight alkaloids were isolated from the bulb of Fritillaria wabuensis S. Y. Tang et S. C. Yueh (Liliaceae), which is efficacious against cough. Five of them are known and identified as imperialine ( 1), peimisine ( 2), ebeinone ( 3), isoverticine ( 4), and imperialine beta- N-oxide ( 5), respectively. Alkaloid 5 is however, controversial. All the signals for both (1)H- and (13)C-NMR spectra of 5 were assigned unambigously by 2D NMR experiments, and (13)C-NMR assignments previously described in the literature were revised. An X-ray structure of alkaloid 5 is presented.