Seven new monoterpenoid indole alkaloids from Gelsemium elegans

Seven new indole alkaloids were isolated from the roots of Gelsemium elegans Benth. and their structures were determined by spectroscopic analysis and chemical transformation from known alkaloids. Kounaminal (1) is a new koumine-type alkaloid that contains an unusual aminal moiety. Humantenoxenine (2) and 15-hydroxyhumantenoxenine (3) are humantenine-type alkaloids that contain a novel β-amino-α,β-unsaturated ketone residue. The other four novel alkaloids are two gelsedilam-related and two gelsenicine-related alkaloids.