The mechanism of action of cyclopropamitosenes, novel bioreductive ant
icancer agents, has been investigated using a unique combination of ch
emical and blochemical techniques. The compounds 4 function as reducti
vely activated alkylating agents under chemical reducing conditions, a
nd the blochemical experiments establish that the methoxy- and aziridi
nyl-derivatives 4a and 4b behave differently upon bioreduction.