Fig. 5.

Stability of arctigenin (AR, 0.8 μg/ml), arctigenic acid (AA, 0.8 μg/ml), and bile (1:50, v/v, 15 min collection after intravenous administration of 0.96 mg/kg AR in SD rats) in a simulated gastric and intestinal fluid (SGF/SIF), b rat gastric and small intestine content solution (rGC/rSIC), c rat large intestine content solution (rLIC), d the conversion of AA to AR in rLIC, and e hydrolysis of glucuronic acid conjugated metabolites in rLIC. All experiments were carried out at 37°C. Metabolites monitored in bile were arctigenin-4′-O-glucuronide (AG), 4-O-demethyl-arctigenin-4,4′-O-di-glucuronide (DA-diG), and arctigenic acid-4′-O-glucuronide (AAG)