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 α,β-unsaturated ester side chain adjacent to the Αγ-lactone and either a primary or secondary allylic alcohol or both.