Four Novel Gelsenicine-Related Oxindole Alkaloids from the Leaves of Gelsemium elegans Benth.

Abstract
New types of four gelsenicine-related oxindole alkaloids were isolated from the leaves of Gelsemium elegans Benth. Gelsedilam (1) and 14-acetoxygelsedilam (2) are the first examples of 18,19-nor-type monoterpenoid indole alkaloids. Gelsefuranidine (3) and gelseiridone (4) have, respectively, an additional furan residue or an iridoid unit on the gelsenicine-related monoterpenoid indole alkaloid.