Identification of key metabolites of tectorigenin in rat urine by HPLC-MS(n).

This is a report about the identification of key metabolites of tectorigenin in rat urine using high-performance liquid chromatography-electrospray ionization ion trap tandem mass spectrometric method (HPLC-ESI-MS(n)). Six healthy rats were administered a single dose (80 mg/kg) of tectorigenin by oral gavage. Urine was sampled for 0-24 h and centrifuged at 12,000 rpm for 10 min to obtain the supernatants, then the supernatants were purified by solid-phase extraction with a C(18) cartridge. The chromatographic separation was carried out on a reversed-phase C(18) column with a gradient elution program whereas acetonitrile-0.1% formic acid water was used as mobile phase. Mass spectra were acquired in negative ionization mode and a data-dependant scan was used for the identification of the key metabolites of tectorigenin in the urine samples. As a result, four phase II metabolites and the parent drug tectorigenin were found and identified in rat urine for the first time.