华北白桦(Betula platyphylla)腐烂的侧树皮以氯仿(31)室温提取一夜。除去溶媒后的残渣进一步以甲醇(31)回流提取2次(5h),收集提取液,减压浓缩成糖浆,糖浆经硅胶柱层析,以乙酸乙酯-甲醇和氯仿-乙酸乙酯洗脱,得化合物1.根据光谱数据,确定该化合物的结构为(17R,20R)-7β,20,23,29-四羟-28-去甲羽扇豆烷-3,16-二酮。 The rotted bark of Betula platyphylla was extracted overnight at room temperature with chloroform (31). The solvent-removed residue was further extracted with methanol (31) twice (5 h). The extract was collected and concentrated under reduced pressure to a syrup. The syrup was subjected to silica gel column chromatography and eluted with ethyl acetate-methanol and chloroform-ethyl acetate. Compounds 1. Based on the spectral data, the structure of this compound was determined to be (17R,20R)-7β,20,23,29-tetrahydroxy-28-decamerolane-3,16-dione.