白首乌甙A、B和C的结构

从著名中药白首乌(Cynanchum auricutatum Royle ex Wight)根中分离得到7个C_2(?)体甙。其小4个已知物——wilfosidc C3N (Ⅰ), C1N (Ⅱ), C1G (Ⅲ), K1N (Ⅴ),和另外3个新C_(21)甾体甙,命名为白首乌甙A (Ⅵ),B (Ⅶ),C(Ⅳ) (cynauricusidc A, B,C)。经光谱数据分析和化学反应,证明其结构分别为:开德甙元 3-氧-β D-葡萄糖吡喃基-(1→4)-α-L-加拿大麻糖吡喃基-(1→4)-β-D-加拿大麻糖吡喃基-(1→4)-α-L-迪吉糖吡喃基-(1→4)-β-D-加拿大麻糖吡喃甙(kidjoranin 3-O-β-D-glucopyranosyl-(1→4)-α-L-cymaropyranosy-(1→4)-β-D-cymaropyranosyl-(1→4)-α-L-diginopyranosyl-(1→4)-β-D-cymaropyranoside, Ⅵ);萝藦甙元 3-氧-α-L-加拿大麻糖吡喃基-(1→4)-β-D-加拿大麻糖吡喃基-α-L-迪吉糖吡喃基-(1→4)-β-D-加拿大麻糖吡喃甙(metaplexigenin -O-α-L-cymaropyranosyl-(1→4)-β-D-cymaropyranosyl-(1→4)-α-L-diginopyranosyl-(1→4)-β-cymaropyranoside,Ⅶ);告达庭 3-氧-β-D-葡萄糖吡喃基-(1→4)-β-L-葡萄糖吡喃基-(1→4)-α-L-加拿大麻糖吡喃基-(1→4)-β-D-加拿大麻糖吡喃基-(1→4-α-L-迪吉糖吡喃基-(1→4)-β-D-加拿大麻糖吡喃基(caudatin 3-O-β-D-glucopyranosy-(1→4)