目的　从萝科鹅绒藤属植物耳叶牛皮消 (CynanchumauriculatumRoyleexWight)块根中分离出有细胞毒活性的 2种C2 1甾体苷。方法　用柱色谱和HPLC法分离纯化 ,通过化学降解及光谱分析 (UV ,IR ,1HNMR ,13 CNMR ,DEPT ,HR FAB MS ,FAB MS ,HMQC和HMBC)鉴定其化学结构。结果　从白首乌中分离得到白首乌新苷A(I)与B(II) ,其化学结构分别为 :告达庭 3 O β D 葡吡喃糖基 (1→ 4) β D 磁麻吡喃糖基 (1→ 4) β D 夹竹桃吡喃糖基 (1→ 4) β D 磁麻吡喃糖苷 ;告达庭 3 O β D 葡吡喃糖基 (1→ 4) β D 夹竹桃吡喃糖基 (1→ 4) β D 洋地黄毒吡喃糖基 (1→ 4) β D 磁麻吡喃糖苷。 结论　白首乌新苷A和B均为新C2 1甾体苷 Objective To isolate two cytotoxic C 2 1 steroidal glucosides from the root of Cynanchum uriculatum Royleex Wight. Methods The compounds were isolated and purified by column chromatography and HPLC. Their chemical structures were identified by chemical degradation and spectroscopic analysis (UV, IR, 1HNMR, 13CNMR, DEPT, HR FAB MS, FAB MS, HMQC and HMBC). Results The new glycosides A(I) and B(II) were isolated from the root of P. bracteatum. Their chemical structures were as follows: Gadacin 3 O β D glucopyranosyl (1→4) β D magnetic hemp Pyranosyl (1→4) β D oleandrol pyranosyl (1→4) β D naphthopyranoside; Chedamate 3 O β D glucopyranosyl (1→4) β D Oleander pyranosyl (1→4) β D digoxigenopyranosyl (1→4) βD magnetopyranoside. Conclusion The new glycosides A and B of P. bracteatum are new C2 1 steroid glycosides