Cytotoxic germacrane-type sesquiterpene lactones from the whole plant of Inula cappa

Two new germacrane-type sesquiterpene lactones, named ineupatolides D and E (1 and 2), were isolated from the whole plant of Inula cappa. Compound 2 is the first example of germacrane-type sesquiterpene lactone with both a 2,5-epoxide and a 5,10-epoxide linkages.