Croomine- and tuberostemonine-type alkaloids from roots of Stemona tuberosa and their antitussive activity

Three new croomine-type Stemona alkaloids, tuberocrooline (1), 10-hydroxycroomine (2), and dehydrocroomine (3), and four new tuberostemonine-type alkaloids, tuberostemoline (4), triclehydrotuberostemonine (5), 9 alpha-bisdehydrotuberostemonine (6), and 9 alpha-bisdehydrottiberostemonine A (7), along with ten known constituents, were isolated from the roots of Stemona tuberosa collected from Yunnan province. The structures of the new compounds were established on the basis of one- and two-dimensional NMR spectra and other spectroscopic studies. The antitussive activity of the major alkaloids was tested using the Citric acid-induced guinea pig cough model. Croomine (8) exhibited a dose-dependent inhibition of coughing with an ID50 value of 0.18 mmol/kg. (c) 2008 Elsevier Ltd. All rights reserved.