| Abstract: | Baicalin, mainly isolated from Scutllaria baicalensis, has been reported to possess a wide range of biological activities. However, the information about the metabolic route and metabolites of baicalin was limited to the role of the human intestinal bacterial mixture. In this paper, four strains of bacteria including Bacteroides sp. 33 and 56, and Veillonella sp. 23 and 71 were isolated from human intestinal bacterial mixture and studied for their abilities to convert baicalin to different metabolites. A highly sensitive and specific ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) method combined with mass defect filtering (MDF) provides high throughput capabilities for drug metabolism study. The chromatographic separation was performed on a 1.7 µm particle size C 18 column using gradient elution system. The components in the extract were identified and confirmed according to the mass spectrometric fragmentation mechanisms, MS/MS fragment ions and relevant literature by means of electrospray ionization mass spectrometry in negative ion mode. With this method, a total of 4 metabolites were identified based on MS and MS/MS data. The results indicated that hydrogenation, methylation, and deglycosylation were the major metabolic pathways of baicalin in vitro. The present study provides important information about the metabolism of baicalin which will be helpful for fully understanding the impact of the intestinal bacteria on this active component. Furthermore, this work demonstrated the potential of the ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry approach for a rapid, simple, reliable, and automated identification of metabolites of natural products. |
