Chemical investigation on Sijunzi decoction and its two major herbs Panax ginseng and Glycyrrhiza uralensis by LC/MS/MS

Sijunzi decoction consists of Panax ginseng, Poria cocos, Atractylodes macrocephala and Glycyrrhiza uralensis. High performance liquid chromatography coupled with tandem mass spectrometry (LC/MSⁿ) was applied to identify and characterize three types of active components, ginsenoside (from P. ginseng), flavonoid and triterpenoid (from G. uralensis) in Sijunzi decoction. Spectra of MS and MS/MS from [M + Na]⁺ ions of ginsenosides were acquired and interpreted for their identification. Fragmentations with losing masses of 194 or 176 Da were the characteristic ions of triterpenoids in the MS/MS analysis. A characteristic fragment ion of the aglycon moiety at m/z 257 from source collision-induced dissociation was observed for flavonoid. LC/MS was also applied for the comparison of relative peak area of major active components between Sijunzi decoction and the single herb extracts. The concentration ratios of major active components detected in the individual herbs of P. ginseng and G. uralensis were found different from those in Sijunzi decoction. The experimental data indicated that the decocting process could result in the difference in the amount of active components.