Development and validation of an LC-ESI-MS/MS method for the quantitation of hemslecin A in rhesus monkey plasma and its application in pharmacokinetics.

In this study, a new LC-ESI-MS/MS-based method was validated for the quantitation of hemslecin A in rhesus monkey plasma using otophylloside A as internal standard (IS). Hemslecin A and the IS were extracted from rhesus monkey plasma using liquid-liquid extraction as the sample clean-up procedure, and were subjected to chromatography on a Phenomenex Luna CN column (150 × 2.0 mm, 3.0 µm) with the mobile phase consisting of methanol and 0.02 mol/mL ammonium acetate (55:45, v/v) at a flow rate of 0.2 mL/min. Detection was performed on an Agilent G6410B tandem mass spectrometer by positive ion electrospray ionization in multiple reaction monitoring mode, monitoring the transitions m/z 580.5 [M + NH4 ](+) → 503.4 and m/z 518.2 [M + NH4 ](+) → 345.0 for hemslecin A and IS, respectively. The assay was linear over the concentration range of 0.5-200 ng/mL and was successfully applied to a pharmacokinetic study in rhesus monkeys.

Scutellarin inhibits cytochrome P450 isoenzyme 1A2 (CYP1A2) in rats.

Scutellarin is the most important flavone glycoside in the herbal drug Erigeron breviscapus (Vant.) Hand.-Mazz. It is used frequently in the clinic to treat ischemic vascular diseases in China. However, the direct relationship between scutellarin and cytochrome P450 (CYP450) is unclear. The present study investigated the in vitro and in vivo effects of scutellarin on cytochrome P450 1A2 (CYP 1A2) metabolism. According to in vitro experiments, scutellarin (10-250 µM) decreased the formation of 4-acetamidophenol in a concentration-dependent manner, with an IC50 value of 108.20 ± 0.657 µM. Furthermore, scutellarin exhibited a weak mixed-type inhibition against the activity of CYP1A2 in rat liver microsomes, with a K(i) value of 95.2 µM. Whereas in whole animal studies, scutellarin treatment for 7 days (at 5, 15, 30 mg/kg, i.p.) decreased the clearance (CL), and increased the T(1/2) (at 15, 30 mg/kg, i.p.), it did not affect the V(d) of phenacetin. Scutellarin treatment (at 5, 15, 30 mg/kg, i.p.) increased the AUC(0-∞) by 14.3%, 67.3% and 159.2%, respectively. Scutellarin at 30 mg/kg also weakly inhibited CYP1A2 activity, in accordance with our in vitro study. Thus, the results indicate that CYP1A2 is inhibited directly, but weakly, by scutellarin in vivo, and provide useful information on the safe and effective use of scutellarin in clinical practice.

Plasma pharmacokinetics and tissue distribution study of roemerine in rats by liquid chromatography with tandem mass spectrometry (LC-MS/MS).

In the present study, a new LC-MS/MS method for the determination of roemerine in rat plasma and tissue samples was developed and successfully used to study the pharmacokinetics and tissue distribution of roemerine after oral and intravenous (i.v.) administration in rats. The plasma and tissue samples were processed by liquid-liquid extraction with n-hexane. Isocorydine was used as the internal standard (IS) for sample processing and analysis. The MS/MS detection was carried out by monitoring the transitions of m/z 280→249 and m/z 342→279 for roemerine and the IS, respectively. The calibration curve displayed excellent linearity over the concentration range of 10-2000ng/mL (n=8, r(2)≥0.995), and the lower limit of quantification (LLOQ) was determined to be 10ng/mL. This method was rapid, accurate, highly sensitive, and fully validated. The pharmacokinetic study showed that roemerine was rapidly absorbed and eliminated with a tmax of 0.22±0.08h, t1/2 of 1.59±0.46h, CL of 4.44±0.42L/h/kg, and Vd of 10.16±2.95µg/L following oral administration. Additionally, roemerine showed an excellent oral bioavailability of 84% and a wide tissue distribution with brain penetration. Highest concentrations of roemerine were found in the liver and lung, followed by kidney, spleen, heart, and brain, in that order.

Comparative pharmacokinetics of swertiamarin in rats after oral administration of swertiamarin alone, Qing Ye Dan tablets and co-administration of swertiamarin and oleanolic acid.

ETHNOPHARMACOLOGICAL RELEVANCE: Qing Ye Dan is a well-known herbal drug that is widely used to treat viral hepatitis in the Yi and Hani minority regions in the Yunnan province of China. MATERIALS AND METHODS: An LC-MS/MS method was developed to determine the levels of swertiamarin in rat plasma. Swertiamarin and naringin (internal standard, IS) were extracted from rat plasma using solid-phase extraction (SPE) to purify the samples. The pharmacokinetics of the following different administration methods of swertiamarin in rats were studied: oral administration of swertiamarin alone, a Qing Ye Dan tablet (QYDT) and co-administration of swertiamarin and oleanolic acid, with each method delivering approximately 20mg/kg of swertiamarin. Non-compartmental pharmacokinetic profiles were constructed by using the software DAS (version 2.1.1), and the pharmacokinetic parameters were compared using an unpaired Student's t-test. RESULTS: The results showed that the pharmacokinetic parameters Cmax, AUC0-∞, Vz/F and CLz/F were significantly different (P<0.05) among the three types of swertiamarin administration. CONCLUSIONS: The data indicate that oleanolic acid and the other ingredients present in QYDT could affect the pharmacokinetic behaviour of swertiamarin in rats.

Development and validation of a LC-ESI-MS/MS method for the determination of swertiamarin in rat plasma and its application in pharmacokinetics.

A new LC-ESI-MS/MS assay method has been developed and validated for the quantification of swertiamarin, a representative bioactive substance of Swertia plants, in rat plasma using gentiopicroside, an analog of swertiamarin on chemical structure and chromatographic action, as the internal standard (IS). The swertiamarin and IS were extracted from rat plasma using solid-phase extraction (SPE) as the sample clean-up procedure, and they were chromatographed on a narrow internal diameter column (Agilent ZORBAX ECLIPSE XDB-C(18) 100 mm × 2.1 mm, 1.8 µm) with the mobile phase consisting of methanol and water containing 0.1% acetic acid (25:75, v/v) at a flow rate of 0.2 mL/min. The detection was performed on an Agilent G6410B tandem mass spectrometer by negative ion electrospray ionisation in multiple-reaction monitoring mode while monitoring the transitions of m/z 433 [M+CH(3)COO](-)→179 and m/z 415 [M+CH(3)COO](-)→179 for swertiamarin and IS, respectively. The lower limit of quantification (LLOQ) was 5 ng/mL within a linear range of 5-1000 ng/mL (n=7, r(2)≥0.994), and the limit of detection (LOD) was demonstrated as 1.25 ng/mL (S/N≥3). The method also afforded satisfactory results in terms of sensitivity, specificity, precision (intra- and inter-day), accuracy, recovery, freeze/thaw, long-time stability and dilution integrity. This method was successfully applied to determination of the pharmacokinetic properties of swertiamarin in rats after oral administration at a dose of 20 mg/kg. The following pharmacokinetic parameters were obtained (mean): maximum plasma concentration, 1920.1 ng/mL; time to reach maximum plasma concentration, 0.945 h; elimination half-time, 1.10h; apparent total clearance, 5.638 L/h/kg; and apparent volume of distribution, 9.637 L/kg.