Discovery and verification of antidepressant active ingredients of raw and vinegar-processed Bupleurum marginatum var. Stenophyllum based on plant metabolomics and serum pharmacology

The dried root of Bupleurum marginatum var. stenophyllum (H. Wolff) R.H. Shan & Y. Li (BM), which has been used as a Bupleuri radix in Guizhou Province and is listed in the 2003 edition of the Guizhou Quality Standard for Traditional Chinese Medicines and Ethnic Materia Medica, is effective at dispersing the liver and relieving depression and often used in the form of raw or vinegar-processed product (VBM). However, the potential depression-relieving components of BM are unclear. The aim of this study was to determine the potential antidepressant constituents of BM and investigate the effect of vinegar processing on these components. The antidepressant effect and mechanism of BM and VBM were investigated in depressed mice and BV2 cells, respectively. The pharmacodynamic constituents were screened through serum pharmacochemistry, which combined the results of metabolomics analysis of BM and VBM, high-performance liquid chromatography (HPLC) content determination, and verification of the antidepressant effect and mechanism of differential components of SSb2 to clarify the connotation of vinegar processing. Our results demonstrated that BM can exert a significant antidepressant effect by inhibiting microglia polarization and that this effect was enhanced after vinegar processing. Thirty-eight components were identified in the BM, 13 of which were blood-absorbable, mainly saponins, and defined as potential antidepressant components of the BM. The contents of 17 components—6 of which were absorbed into the blood—changed considerably after processing. It was finally determined that vinegar processing can enhance the antidepressant effect of BM by increasing the contents of SSb1 and SSb2. SSb2 exerts this effect via the samemechanism as BM. In conclusion, in this study we clarified the antidepressant effects and potential active components of BM and examined the mechanism of vinegar processing. These findings lay a foundation for the future research on the antidepressant effects of BM as well as for the complete development and application of BM's ethnomedicinal resources.