Sesquiterpene lactones and flavonoids from Helianthus species.

From the leaves and the flowers of Helianthus glaucophyllus and Helianthus microcephalus, three new guaianolides were isolated. H. microcephalus afforded another two new guaianolides, the highly unsaturated guaianolide, the flavane, the flavone, and three flavonols. Structures of all the compounds were determined by spectral analysis.