Pharmacokinetics of isocorynoxeine in rat plasma after intraperitoneal administration by UPLC–MS/MS

Abstract

Isocorynoxeine is one of the main alkaloids in Chinese medicinal herbs, and has pharmacological activities such as antihypertensive, sedative, anticonvulsant, and neuronal protection. It is an effective component of Uncaria for the treatment of hypertension. In this study, we used a fast and sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) to detect isocorynoxeine in rat plasma and investigated its pharmacokinetics in rats. Six rats were given isocorynoxeine (15 mg/kg) by intraperitoneal (i.p.) administration. Blood (100 μL) was withdrawn from the caudal vein at 5 and 30 min and 1, 2, 4, 6, 8, 12, and 24 h after administration. Chromatographic separation was achieved using a UPLC BEH C18 column using a mobile phase of acetonitrile–0.1% formic acid with gradient elution. Electrospray ionization (ESI) tandem mass spectrometry in the multiple reaction monitoring (MRM) mode with positive ionization was applied. Intra-day and inter-day precisions (relative standard deviation, %RSD) of isocorynoxeine in rat plasma were lower than 12%. The method was successfully applied in the pharmacokinetics of isocorynoxeine in rats after intraperitoneal administration. The t1/2 of isocorynoxeine is 4.9 ± 2.1 h, which indicates quick elimination.

Determination of Gypenoside A and Gypenoside XLIX in Rat Plasma by UPLC-MS/MS and Applied to the Pharmacokinetics and Bioavailability

“…e mass spectrometry conditions were obtained after optimizing the spray needle voltage, drying gas temperature, capillary voltage, and collision energy [18][19][20][21]. Comparing the positive and negative modes, gypenoside A and gypenoside XLIX were best suited for detection in ESI negative-ion mode because the sensitivity was signi cantly higher than detection in other modes.…”

“…Stock solutions (500 µg/mL) of gypenoside A, gypenoside XLIX, and the internal standard were prepared in methanol. e stock solutions were diluted with methanol to obtain working solutions of gypenoside A and gypenoside XLIX at a range of concentrations (20,100,200,500,2000,5000,10000,20000, and 30000 ng/mL). All stock and working solutions were stored at 4 °C.…”