Monoterpenoid Indole Alkaloids from the Leaves of Alstonia scholaris

A chemical investigation on the ethanol extract from the leaves of Alstonia scholaris led to the isolation of two new monoterpenoid indole alkaloids, 17-formyl-10-demethoxyvincorine N(4)-oxide (1) and 10-methoxyalstiphyllanine H (2), along with one known alkaloid, 10-demethoxyvincorine N(4)-oxide (3). Their structures were established on the basis of extensive chromatographic properties and chemical and physicochemical methods.