New humantenine-type indole alkaloids with iridoid unit from Gelsemium species

Abstract Two new oxindole alkaloids, rankiniridine ( 1 ) and humanteniridine ( 2 ), having a nitrogen–carbon linkage between a humantenine-type monoterpenoid indole alkaloid and a monoterpene unit with an iridoid skeleton, were isolated from Gelsemium rankinii and Gelsemium elegans , respectively.