Ultra‑performance Liquid Chromatography/Quadrupole Time‑of‑flight Mass Spectrometry Analysis of In vitro Metabolites of Lignans from Fructus Forsythiae by Human Fecal Flora

Background: Phillyrin and (+)‑pinoresinol 4‑O‑‑D‑glucoside are the major active furofuran‑type lignans in Fructus Forsythiae. The metabolic routes and metabolites of these two lignans are not well understood yet. Objective: In this study, we attempted to identify the human‑intestine bacterial metabolites of lignans from Fructus Forsythiae. Materials and Methods: Two natural compounds, phillyrin and (+)‑pinoresinol 4‑O‑‑D‑glucoside were incubated with human fecal microflora in an anaerobic incubator for 72 h and the metabolites with highly sensitive ultra‑performance liquid chromatography/quadrupole time‑of‑flight mass spectrometry (UPLC‑Q‑TOF/MS) were analyzed. Results: As a result, nine metabolites were determined using a Syncronis™ C18 column (particle size 1.7 mm) in a gradient elution system. These metabolites were then identified according to the mass fragmental mechanism, MS/MS fragment ions, and previous publications. The results of this study indicated that the major metabolites of furofuran‑type lignans are through the processes of hydrolysis, demethylation, reduction, dehydroxylation, and oxidation. Conclusions: Lignans can be metabolized by intestinal microbiota and the intestinal bacteria play a critical role in the metabolism of components administered orally.