TUMOR INHIBITORS .41. STRUCTURAL ELUCIDATION OF TUMOR-INHIBITORY SESQUITERPENE LACTONES FROM EUPATORIUM ROTUNDIFOLIUM

The structure and stereochemistry of eight cytotoxic sesquiterpene lactones from Eupatorium rotundifolium have been determined by relating them to the X-ray-defined structure of euparotin bromoacetate (3). Three of the compounds, eupachlorin (6), eupachlorin acetate (5), and eupachloroxin (13), are the first reported chlorinecontaining sesquiterpenes. Chemical and spectroscopic evidence is advanced for assignment of stereochemically complete structures for these compounds and euparotin (2), euparotin acetate (1), eupatoroxin (7), eupatundin (8), and 10-epieupatoroxin (12). Two of the more abundant compounds, 1 and 5, were also tested in vivo and were found to show tumor-inhibitory activity. © 1969, American Chemical Society. All rights reserved.