目的寻找选择性水解甾体皂苷C-3位糖链末端糖基的微生物,同时制备甾体皂苷的去糖基衍生物.方法利用新月弯孢霉(3.438 1)培养,对C-3位有双糖基结构的甾体皂苷类化合物重楼皂苷Ⅴ(化合物Ⅰ)、重楼皂苷Ⅵ(化合物Ⅱ)进行生物转化;用反相C18开放柱进行转化产物的分离纯化,波谱方法鉴定其结构.结果新月弯孢霉(3.4381)均能将化合物Ⅰ和化合物ⅡC-3位糖链末端的鼠李糖水解,转化为单糖基皂苷,转化产物分别鉴定为薯蓣皂苷元-3-O-β-D-吡喃葡萄糖苷,即延龄草苷(trillin,化合物Ⅲ)和偏诺皂苷元-3-O-β-D-吡喃葡萄糖苷(化合物Ⅳ).结论首次发现新月弯孢霉(3.438 1)对重楼皂苷Ⅴ和重楼皂苷ⅥC-3位糖链的末端鼠李糖具有较强的水解能力.

Objective To find the microorganisms which hydrolyze sugar residues of steroidal saponins at C-3 position and to obtain their glucosyl-derivatives.Methods The enzymes secreted by fermentation ofCurvularia lunata(3.4381)in the culture medium were employed to transform polyphyllin V(compound I)and polyphyllin VI(compoundⅡ).The products were separated by means of chromato-graphy on C18 column and their structures were elucidated on the basis of spectral analyses.Results Compounds I andⅡcould be transformed by C.1unata(3.4381)and the main products were identified as diosgenin-3-0-β-D-glucopyranoside,named trillin (compound 11I)and pennogenin-3-O-8-D-91ucopyranoside(compound IV),respectively.Conclusion The terminal rhamnosyls of polyphy-llin V and polyphyllin VI at C-3 position could be hydrolyzed selectively byC.1unata(3.4381)for the first time.