Three new indole alkaloids from the leaves of Alstonia scholaris

Three new akuamillan-type indole alkaloids, i.e., 5-methoxystrictamine (=methyl (5 beta,16R,19E)-5-methoxyakuammilan-17-oate; 1), methyl (16R,19E)-1,2-dihydro-16-(hydroxymethyl)-5-oxoakuammilan-17-oate (2), and methyl (2 beta 16R,19E)-4,5-didehydro-1,2-dihydro-2-hydroxy-16-(hydroxymethyl)akuammilan-4-ium-17-oate chloride (3), have been isolated from the leaves of Alstonia scholaris, together with ten known compounds. Their structures were determined by spectroscopic means. None of the constituents showed significant cytotoxic activity towards WT cells.