Plasma pharmacokinetics and tissue distribution study of physalin D in rats by ultra-pressure liquid chromatography with tandem mass spectrometry

Physalin D is an important constituent of some traditional Chinese medicines, and has several known bioactivities. An UPLC–MS/MS method for the determination of physalin D in rat plasma and tissues was developed and the pharmacokinetic and tissue distribution characteristics of physalin D after intravenous administrations were investigated. The bio-samples were prepared by a simple protein precipitation, and the separation of physalin D was achieved on a UPLC HSS T3 column with a mobile phase consisting of methanol/acetonitrile (70:30, v/v) and water (containing 0.1% formic acid and 10 mM ammonium acetate) at a flow rate of 0.3 mL/min. The MS/MS detection was carried out by monitoring the fragmentation of m/z 544.9 → 508.8 for physalin D and m/z 286.7 → 152.8 for luteolin (internal standard; IS) on a triple-quadrupole mass spectrometer. The total run time was only 3.6 min. The analyte showed good linearity over a wide concentration range (R2 > 0.995) and its lower limit of quantification was 2 ng/mL. The pharmacokinetic study found that physalin D was distributed and eliminated rapidly in rats (t1/2 < 10 min). Tissue distribution showed the highest level was observed in kidney, then in liver, but no physalin D was detected in brain, which indicated that kidney was the major distribution tissue for physalin D in rats and that physalin D does not cross the blood–brain barrier.