New Indole Alkaloids from the Bark of Alstonia scholaris

A new indole alkaloid, akuammiginone (1), and a new glycosidic indole alkaloid, echitamidine-N-oxide 19-O-β-d-glucopyranoside (2), together with the five known alkaloids, echitaminic acid (3), echitamidine N-oxide (4), Nb-demethylalstogustine N-oxide (5), akuammicine N-oxide (6), and Nb-demethylalstogustine (7), were isolated from the trunk bark of Alstonia scholaris collected in Timor, Indonesia. The structures of all compounds were elucidated by spectroscopic methods. This is the first report of compounds 35 and 7 in A. scholaris. Some NMR assignments of the known compounds were revised.