STUDIES ON THE ALKALOIDS OF CEPHALOTAXUS Ⅸ.SEMI-SYNTHESIS OF CEPHALOTAXINE ESTERS AND THEIR ANTILEUKEMIC ACTIVITY

Harringtonine, homoharringtonine, deoxyharringtonine and isoharring-tonine isolated from Cephalotaxus plant are the esters of cephalotaxine with significantinhibitory activity against P- 388 leukemia. In this investigation seventeen new esters ofcephalotaxine type alkaloids have been synthesized. Preliminary pharmacological examina-tion showed that compounds 1, 2, 2+ 3, 6 and 8 showed similar antileukemic activity ashomoharringtonine. Compounds 4, 5, 15 and 16 showed moderate inhibitory activity.Some structure-activity correlations of these esters were discussed.