Holistic quality evaluation of Saposhnikoviae Radix (Saposhnikovia divaricata) by reversed-phase ultra-high performance liquid chromatography and hydrophilic interaction chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry-based untargeted metabolomics

Untargeted metabolomics more suits the quality evaluation of TCM because of its holistic property. To assess the holistic quality difference of Saposhnikoviae Radix (the roots of Saposhnikovia divaricata), we integrate ultra-high-performance liquid chromatography coupled with ion mobility/quadrupole time-of-flight mass spectrometry (UHPLC/IM-QTOF-MS)-based untargeted metabolomics and quantitative assay. A BEH C18 column in the reversed-phase mode and a BEH Amide column in Hydrophilic Interaction Chromatography (HILIC) mode were utilized for metabolites profiling, which enabled high coverage of the non-polar to polar components in Saposhnikoviae Radix. Moreover, the application of major components knockout strategy enlarged the exposure of those minor components. Integrated use of high-definition MSE (HDMSE) and data-dependent acquisition (DDA) could enhance the metabolites characterization by providing reliable fragmentation information and collision cross section values. Computational in-house library-driven automated peak annotation of the HDMSE and DDA data assisted to characterize 104 components from Saposhnikoviae Radix. Chemometric analyses of the commercial Saposhnikoviae Radix samples (64 batches collected from 11 cultivars aging from 1 to 4 years), based on the positive MSE data, in general could indicate large discrimination between Guan-Fang-Feng (from Heilongjiang) and the others, but negligible difference among Saposhnikoviae Radix from the other ten provinces of China and with different ages. Quantitative assays of prim-O-glucosylcimifugin and 4′-O-β-D-glucosyl-5-O-methylvisamminol, by a rapid and fully validated UHPLC-UV method, could primarily deduce that Guan-Fang-Feng aging 2 and 3 years exhibited better quality. The methods established can holistically assess the quality of TCM with wide spans of plant metabolites covered.

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2. Experimental section

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