Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, China.
J Mass Spectrom. 2012 Oct;47(10):1313-21. doi: 10.1002/jms.3085.
For identification of ginsenoside enantiomers, electrospray ionization mass spectrometry (ESI-MS) was used to generate silver complexes of the type ginsenoside + Ag. Collision induced dissociation of the silver-ginsenoside complexes produced fragment ions by dehydration, allowing differentiation of ginsenoside enantiomers by the intensity of M + Ag - H(2)O ion. In the meanwhile, an approach based on the distinct profiles of enantiomer-selective fragment ion intensity varied with collision energy was introduced to refine the identification and quantitation of ginsenoside enantiomers. Five pairs of enantiomeric ginsenosides were distinguished and quantified on the basis of the distribution of fragment ion M + Ag - H(2)O. This method was also extended to the identification of other type of ginsenoside isomers such as ginsenoside Rb2 and Rb3. For demonstrating the practicability of this novel approach, it was utilized to analyze the molar ratio of 20-(S) and 20-(R) type enantiomeric ginsenosides in enantiomer mixture in red ginseng extract. The generation of characteristic fragment ion M + Ag - H(2)O likely results from the reduction of potential energy barrier of dehydration because of the catalysis of silver ion. The mechanism of enantiomer identification of ginsenosides was discussed from the aspects of computational modeling and internal energy.
为了鉴定人参皂苷对映异构体，采用电喷雾电离质谱（ESI-MS）生成了[人参皂苷+Ag]+型银络合物。银-人参皂苷络合物的碰撞诱导解离通过脱水产生碎片离子，通过[M+Ag-H2O]+离子的强度来区分人参皂苷对映异构体。同时，引入了一种基于与碰撞能变化相关的对映体选择性碎片离子强度特征分布的方法，以改进人参皂苷对映异构体的鉴定和定量。基于碎片离子[M+Ag-H2O]+的分布，区分并定量了五对对映体人参皂苷。该方法还扩展到了其他类型的人参皂苷异构体（如人参皂苷 Rb2 和 Rb3）的鉴定。为了证明这种新方法的实用性，将其用于分析红参提取物中人参皂苷对映体混合物中 20-（S）和 20-（R）型对映体人参皂苷的摩尔比。特征碎片离子[M+Ag-H2O]+的生成可能是由于银离子的催化作用降低了脱水的势能垒。从计算建模和内部能量的角度讨论了人参皂苷对映异构体的鉴定机制。
