Simultaneous quantification and rat pharmacokinetics of formononetin-7-O-β-d-glucoside and its metabolite formononetin by high-performance liquid chromatography-tandem mass spectrometry.

Formononetin-7-O-β-d-glucoside has been proved to have significant anti-inflammatory effect. To evaluate its rat pharmacokinetics, a rapid, sensitive, and specific liquid chromatography-tandem mass spectrometry method has been developed and validated for the quantification of formononetin-7-O-β-d-glucoside and its main metabolite formononetin in rat plasma. Samples were pretreated using a simple protein precipitation and the chromatographic separation was performed on a C column by a gradient elution using a mobile phase consisting of water and acetonitrile both containing 0.1% formic acid. Both analytes were detected using a tandem mass spectrometer in positive multiple reaction monitoring mode. The assay showed wide linear dynamic ranges of both 0.10-100 ng/mL, with acceptable intra- and inter-batch accuracy and precision. The lower limits of quantification were both 0.10 ng/mL using 50 μL of rat plasma for two analytes. The method has been successfully used to investigate the oral pharmacokinetic profiles of both analytes in rats. After oral administration of formononetin-7-O-β-d-glucoside at the dose of 50 mg/kg, it was rapidly absorbed in vivo and metabolized to its metabolite formononetin. The plasma concentration-time profiles both showed double-peak phenomena, which would be attributed to the strong enterohepatic circulation of formononetin-7-O-β-d-glucoside.