Multimodal analytical strategy for revealing the related compounds of color variation in Salvia miltiorrhiza after sweating.

This study investigated the color-related compounds of Salvia miltiorrhiza after sweating. Stereomicroscopy and Electronic eye system were employed to characterize color variation. UPLC-Q-Orbitrap-MS and HPLC identified differential compounds. Furthermore, μ-FTIR and MALDI-MSI visualized the spatial distribution of compounds, and the compounds distribution was confirmed via HPLC. Result showed that after sweating, the appearance characteristics of Salvia miltiorrhiza changed significantly, exhibiting a reddish-brown epidermis and purple-brown inner tissue. Among 49 significantly altered compounds, tanshinones accounted for 58%. HPLC further indicated that the content of tanshinones showed a significant increase. Integrated μ-FTIR and MALDI-MSI demonstrated tanshinones increased after sweating and accumulated in the epidermis. Further confirmation of the increase in tanshinones was achieved by HPLC analysis of epidermis and cortex isolated. These results reveal tanshinones as the color-related compounds and clarify their spatial distribution, providing insights into the chemical changes during the traditional sweating process of Salvia miltiorrhiza.