STUDIES ON THE ALKALOIDS OF CEPHALOTAXUS I.THE ISOLATION AND CHARACTERIZATION OF ANTILEUKEMIC ALKALOIDS TOGETHER WITH A NEW ALKALOID(+)-ACETYLCEPHALOTAXINE FROM CEPHALOTAXUS FORTUNEI

ABSTRACT Ten alkaloids have been isolated from the twigs and leaves of cephalotaxus fortunei Hook.f.native in China.Four of them are proved to be identical with known alkaloids:cephalotaxine(Ⅰ),harringtonine(Ⅱ),homoharringtonine(Ⅲ)and desmethyl- cephalotaxinone(Ⅳ).One of them is a new alkaloid,“alkaloid CF5”.Its structure is proved to be(+)-acetylcephalotaxine(Ⅴ)by chemical and spectroscopic methods. Evidence is presented to show that(+)-acetylcephalotaxine is an enantiomer of acetylcephalotaxine(I_a)prepared by ordinary procedure from cephalotaxine(Ⅰ). (+)-cephalotaxine(Ⅵ)was obtained by alkaline hydrolysis of(+)-acetylcephalotaxine (Ⅴ). Ⅱ and Ⅲ show antileukemic activity in preliminary clinical tests.