Structure-activity relationships among in vivo active germacranolides.

Nine structurally related germacranolides from Eupatorium semiserratum and Eriophyllum confertiflorum were assayed in two standard tumor systems (PS and KB) to determine the structural features required for in vivo antileukemic activity. The moieties necessary for in vivo activity were found to be an alpha,beta-unsaturated ester side chain adjacent to the gamma-lactone and either a primary or secondary allylic alcohol or both.