Tissue distribution of six major bio-active components after oral administration of Zhenqi Fuzheng capsules to rats using ultra-pressure liquid chromatography-tandem mass spectrometry.

Radix Astragali (Huangqi in Chinese) and Fructus Ligustri Lucidi (Nvzhenzi in Chinese) (2:1, w/w) are combined in an herbal formulation called Zhenqi Fuzheng capsules (ZFCs) for use in China to improve immunity, promote the recovery of normal functions after surgical operations, and as the most important adjuvant therapy in cancer. In this study, the tissue distribution profiles of the six major bio-active constituents (calycosin-7-O-β-D-glucoside, ononin, calycosin, formononetin, astragaloside IV and astragaloside II) were examined after oral administration of ZFCs to rats. All six constituents in each tissue were detected simultaneously using UPLC-ESI-MS, and the concentration of each constituent per gram of each tissue was determined. Quantification was performed using low-energy collision tandem mass spectrometry (CID-MS/MS) in multiple reaction monitoring (MRM) scan mode for the following precursor ion→product ion transitions at m/z 447.21→285.30 for calycosin-7-O-β-D-glucoside, m/z 285.29→270.38 for calycosin, m/z 431→269 for ononin, m/z 269→237 for formononetin, m/z 807.40→627.50 for astragaloside IV, m/z 849.60→669.65 for astragaloside II and m/z 633.18→331.18 for the internal standard (hesperidin). The results showed that in general the tissue concentrations for all six constituents were in the following order: spleen>stomach>thymus>lung>liver>kidney>heart>testicle. The high levels in the spleen and thymus indicated that all six compounds accumulated in organs involved in the immune response, consistent with the immunity effects of ZFC. The high levels in the stomach were consistent with the oral administration of ZFC. This study was the first to compare the tissue distribution of calycosin-7-O-β-D-glucoside with that of calycosin or of ononin with that of formononetin in rats. It was also the first study to examine the tissue distribution of astragaloside II, calycosin and formononetin following oral administration of ZFC to rats.