Institute for Organic Chemistry, Technical University of Berlin, D-1000 Berlin 12, Germany
a Smithsonian Institution, Department of Botany, Washington DC 20560, U.S.A.
b East African Herbarium, Nairobi, Kenya
Abstract:
The investigation of two East African and a Madagascarian Vernonia species afforded several new sesquiterpene lactones. Vernonia colorata subsp. grandis gave 19-hydroxyglaucolide A and three vernodalin derivatives, V. holstii five new cistifoliolides and V. zanzibarensis five lactones closely related to brachycalyxolide. The structures were elucidated by high field NMR techniques. The chemotaxonomic relevance is discussed briefly.