Abstract: Using non-targeted metabolomics based on ultra-high performance liquid chromatography-quadrupole Orbitrap high resolution mass spectrometry, this study systematically analyzed changes in the metabolite profile of Wushan-grown Codonopsis tangshen Oliv. roots across different stages of heat pump drying and elucidated the formation mechanism of lobetyolin, a key active substance. In total, 1 847 and 1 480 metabolites were detected in the positive and negative ion modes, respectively. The types and amounts of differential metabolites tended to stabilize after 8 hours of drying, while the composition of metabolites changed significantly. The abundance of lobetyolin increased 315-fold from 6 h to the end of drying. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the down-regulation of linoleic acid metabolism facilitated the generation of fatty acid chains in a precursor of lobetyolin, while the down-regulation of metabolic pathways related to starch and sucrose provided glycosyl groups for another precursor, glucopyranoside. Both of these effects contributed to the generation of lobetyolin during the drying process. This study has revealed the intrinsic mechanism by which heat pump drying improves the quality of Wushan-grown C. tangshen Oliv. roots at the metabolic level and clarified the chemical basis for the accumulation of the key active component.

Key words: Wushan-grown Codonopsis tangshen Oliv. roots; heat pump drying; lobetyolin; metabolomics; key active component