Metabolomics analysis reveals metabolite changes during freeze-drying and heat drying of Angelica dahuric

Abstract Angelica dahurica (Angelica dahurica Fisch. ex Hoffm.) is a traditional Chinese medicine with active ingredients, including coumarins and volatile oil. Drying is closely associated with the qualities of Chinese medicinal materials. An increasing body of evidence suggests that coumarin content is upregulated with increased temperature within a certain range; however, the underlying mechanism remains unclear. This study sought to determine the key differential metabolites and metabolic pathways related to this phenomenon. Liquid Chromatography with tandem mass spectrometry (LC-MS/MS) based targeted metabolomics analysis was performed on Angelica dahurica that were freeze-dried and heat dried. 995 metabolites were detected, and 193 differentially metabolites were identified as key differential metabolites, most of which were upregulated under heat drying. Furthermore, the common metabolic pathways of paired comparison groups were performed based on KEEG annotation and enrichment analysis. It is speculated that the increase of coumarin content is caused by phenylalanine pathway activation under moderate heat treatment. This study revealed the large-scale recombination events of metabolites in Angelica dahurica. First, we identified additional active secondary metabolites apart from coumarins, and volatile oil was significantly accumulated in Angelica dahurica. We further explored the specific metabolite changes and mechanism of the phenomenon of coumarin upregulation caused by temperature rise. These results provide a theoretical reference for future research on the composition and processing method of Angelica dahurica.