三尖杉酯碱(C_(28)H_(37)NO_9·2H_2O,简称化合物Ⅰ),高三尖杉酯碱(C_(29)H_(39)NO_9,简称化合物Ⅱ)和异三尖杉酯碱(晶体结构待发表)都是从三尖杉树皮中提取的抗癌有效成分,其药理和化学特性已有研究。由于三者的结构不同,抗癌效果也有差异。用X射线衍射法测定它们的三维结构,将有助于了解三者间的结构和功能的关系。 (C_ (28) H_ (37) NO_9 · 2H_2O, abbreviated compound I), homoharringtonine (C_ (29) H_ (39) NO_9, referred to as compound II) and homoharringtonine (Crystal structure to be published) are extracted from the Cephalotaxus bark anti-cancer active ingredients, its pharmacological and chemical properties have been studied. As the three different structures, anti-cancer effect is also different. The determination of their three-dimensional structure by X-ray diffraction will help to understand the relationship between the structure and function of the three.