In situ visual and content changes analysis of coumarins in Radix Angelicae dahuricae by LSCM combined with LC-MS technology

In this study, a simple, accurate and green localization method of coumarins in Radix Angelicae dahuricae was established with fresh Radix Angelicae dahuricae as research material to reveal the distribution and accumulation of coumarins, based on frozen section and fluorescence imaging technology. The best frozen section conditions were established by comparing the effects of different cryoprotectants on the quality of Radix Angelicae dahuricae's frozen sections, according to the loss of coumarins and the complexity of the operation process. The coumarin components in Radix Angelicae dahuricae at different stages were located and quantitatively analyzed, and coumarin components distribution positions and content changes were identified using fluorescence imaging combined with LC-MS technology. The results showed that 30 μm slice thickness with 15 % glycerin protectant treatment is the best condition for frozen section. Fluorescence imaging showed that coumarins in Radix Angelicae dahuricae were mainly distributed in secretory tissue, the content over different periods showed an “S” curve of growth and coumarins reached their highest content in early September. The distribution and accumulation of coumarins in roots were revealed, which provided a reference for the synthesis and metabolism mechanism of metabolites in medicinal plants and the quality evaluation of traditional Chinese medicine.