Pharmacokinetics, tissue distribution and excretion study of dictamnine, a major bioactive component from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae)

• Development and validation of an UHPLC–ESI-MS/MS method for the determination of dictamnine in rat plasma and tissues.
• The method was successfully applied to study pharmacokinetics, tissue distribution and excretion of dictamnine in rats.
• Optimal assay conditions gave detection levels in the range of 0.5–250 ng/mL.

Dictamnine is an herbal ingredient isolated from the root bark of Dictamnus dasycarpus Turcz. (Rutaceae). The present study was aimed at the development of an ultra-high performance liquid chromatography–tandem mass spectrometry method to quantify the concentration of dictamnine in rat plasma and tissues for the in vivo pharmacokinetics, tissue distribution and excretion study. Biological samples were processed with protein precipitation. Skimmianine was chosen as internal standard. The chromatographic separation was carried out on a Thermo Syncronis C18 column (2.1 mm × 50 mm, 1.7 μm) with an isocratic mobile phase consisting of methanol and 0.1% formic acid water (75:25, v/v). The detection was accomplished by using positive ion electrospray ionization in multiple reaction monitoring (MRM) mode. The MS/MS ion transitions were monitored at m/z 200.0 → 129.0 for dictamnine and 260.3 → 227.1 for IS, respectively. An excellent linearity was observed over the concentration range from 0.5 to 250 ng/mL. The lower limit of quantification (LLOQ) was 0.5 ng/mL for dictamnine. The developed method was rapid, accurate, and highly sensitive and selective. It was successfully applied to the in vivo pharmacokinetics, tissue distribution and excretion study of dictamnine in rats after oral or intravenous administration of dictamnine.