Tanaka Ken, Hayashi Kosuke, Fahad Abrar, Arita Masanori
Department of Medicinal Resources, Institute of Natural Medicine, University ofToyama, 2630 Sugitani, Toyama 930-0194, Japan.
Nat Prod Commun. 2011 Jan;6(1):7-10.
The fragmentation pathways of six triterpenoid saponins from Glycyrrhiza radix were investigated using LC-MS/MS. Depending on the structure and the substitution pattern, different molecular adduct ions, [M+NH4]+ or [M+H]+, were observed in the positive ESI spectra. In the positive MSn spectra from the molecular adduct ions, characteristic product ions corresponding to the loss of dehydrated glucuronic acid or glucuronic acid were detected and they indicated the type of substitution and structural modification. Fragment ions originating from the sapogenin moiety in the positive mass spectra were predominantly provided by saponins having an 11-oxo-12-ene structure. On the other hand, the saponins gave fragment ions corresponding to the sugar moiety in the negative mass spectra. These results indicate the specific property of saponins that have the 11-oxo-12-ene structure to localize positive or negative charge in the mass spectrometric ionization and fragmentation process. Information obtained from the present study can be utilized for structural elucidation of triterpenoid saponins in the Glycyrrhiza radix by LC-MS.
利用液相色谱-串联质谱法（LC-MS/MS）研究了甘草中六种三萜皂苷的裂解途径。根据结构和取代模式，在正电喷雾电离（ESI）谱中观察到不同的分子加合离子，即[M+NH4]+或[M+H]+。在分子加合离子的正多级质谱（MSn）谱中，检测到对应于脱水葡萄糖醛酸或葡萄糖醛酸损失的特征性产物离子，它们表明了取代类型和结构修饰。在正质谱中，源自皂苷元部分的碎片离子主要由具有11-氧代-12-烯结构的皂苷提供。另一方面，这些皂苷在负质谱中给出对应于糖部分的碎片离子。这些结果表明了具有11-氧代-12-烯结构的皂苷在质谱电离和裂解过程中使正电荷或负电荷局部化的特殊性质。本研究获得的信息可用于通过LC-MS对甘草中三萜皂苷进行结构解析。
