Biotransformation of luteoloside by a newly isolated human intestinal bacterium using UHPLC-Q-TOF/MS

• Metabolites of luteoloside produced by a newly gut bacteria were firstly investigated.
• The β-d-glucosidase activity of Enterococcus sp. 45 was characterized.
• UPLC-Q-TOF/MS was applied for analysis of the metabolites of luteoloside.

To explore the metabolic pathways and metabolites of luteoloside yielded by the isolated human intestinal bacteria from healthy human feces and characterize the β-d-glucosidase activity of the specific strain which catalyzed the breakdown of luteoloside, a preculture bacterial GAM broth and luteoloside were mixed incubated together for 48 h. UHPLC-Q-TOF/MS was used for analysis of the metabolites of luteoloside in the corresponding supernatant fractions from fermentation. Aliquots of the reactive solutions were collected at different times and were measured with a microplate reader at 405 nm to evaluate the enzymatic activity. Three metabolites (acetylated luteoloside, luteolin and deoxygenated luteolin) were detected in the fractions isolated from the bacterial samples. The variation of β-d-glucosidase activity inside the bacterium was in coincidence with the changes in luteolin generation or luteoloside degradation in different time periods.