1. Graduate School of Pharmaceutical Sciences, Chiba University, 1‐33 Yayoi‐cho, Inage‐ku, Chiba 263‐8522 (Japan), Fax: (+81)?43‐290‐2901;2. Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10500 (Thailand)
Abstract:
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.