Integration of diagnostic ions, molecular network and chemometrics to illustrate the chemical mechanism of Radix Astragali processed with honey

Radix Astragali (RA) is one of the most frequently used traditional Chinese medicine (TCM) in China, and honey-processed RA (HRA) is its common processing product. Thus far, their comprehensive chemical differences are not well understood. In this work, an integrated approach using Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) combined with diagnostic ions, molecular network (MN) and chemometrics was established to profile their chemical characterizations and illustrate the chemical mechanism of RA processed with honey. A total of 226 compounds were tentatively identified including 50 flavonoid glycosides, 26 flavonoid aglycone, 56 saponins, 30 organic acids, 18 amino acids, 3 coumarins and 43 other compounds, of which 33 compounds were characterized according to MN. Their chemical differences were further investigated by integrating of multivariate statistical analysis, student's t-test analysis, linear regression analysis and MN. Consequently, multivariate statistical analysis showed that the raw and processed RA were different form each other. Besides, 33 different compounds were found to be significantly altered by student's t-test analysis. Apart from this, linear regression analysis indicated 42 and 120 compounds underwent the significant varieties. The potential chemical reactions induced by honey-processing, such as possible hydrolysis reactions and isomerization reactions, were speculated based on these variations coupled the areas changes of the nodes in MN. This study provided an efficient strategy to illustrate the chemical mechanism of TCM processing.