SESQUITERPENE LACTONES OF HELENIUM ALTERNIFOLIUM (SPRENG) CABRERA . STRUCTURES OF BREVILIN A LINIFOLIN A AND ALTERNILIN

Helenium alternifolium (Spreng.) Cabrera from near Tucuman, Argentina, furnished primarily tenulin and smaller amounts of brevilin A, previously isolated from H. brevifolium (Nutt.) A. Wood, linifolin A, previously isolated from H. linifolium Rybd., and 6,3′-dimethoxy-5,7,4′-flavone. A collection of H. alternifolium from near La Plata, Argentina, afforded the new sesquiterpene lactone alternilin as the sole crystallizable constituent. Structures of brevilin A, linifolin A, and alternilin have been established. © 1968, American Chemical Society. All rights reserved.