Sesquiterpene lactones and other constituents from Siegesbeckia orientalis and Guizotia scabra

From the aerial parts of Siegesbeckia orientalis, in addition to a known sesquiterpene lactone, nine new germacranolides, three melampolides, three geranylnerol derivatives and three ent-pimarenes were isolated. From Guizotia scabra a new eudesmanolide was obtained. The structures were elucidated by high field NMR techniques. The chemotaxonomic aspects are discussed briefly.