Résumé
Aim To develop an LC-MS/MS method for the determination of prucalopride(PCP)in human plasma.Methods Prucalopride -13CD3(dPCP)was used as the internal standard.The analytes were extracted from human plasma through liquid-liquid extraction method using ethyl acetate, followed by being dried, and then the reconstitution was injected into LC-MS/MS systems.Agilent ZORBAX SB C18(3.0×100 mm, 3.5 μm)column and isocratic elution system composing of methanol and 1 mmol·L-1 ammonium acetate(80:20, V/V)provided chromatographic separation of PCP and dPCP.AB Sciex API4000 mass spectrometer equipped with an electrospray ionization source in positive ion mode was employed for mass detection, and data acquisition was carried out in multiple reaction monitoring(MRM)mode.The mass transition ion-pair was followed as m/z 368.4/196.0 for PCP and m/z 374.4/198.0 for dPCP.Results PCP and dPCP were eluted at 3.6 min, with no interference in human blank plasma.PCP in human plasma showed good linearity over the concentration range of 0.058 96-7.547 μg·L-1 with the correlation coefficient of 0.996 3-0.999 6.The lower limit of quantitation of this method was 0.058 96 μg·L-1.The intra-batch and inter-batch accuracy ranged from 98.29% to 108.2%, with good precision(CV<5.2%).The average matrix factors of normal, haemolysed and lipaemic matrix human samples all ranged from 96.48% to 106.3% with CV less than 8.39%.The average extraction recoveries of PCP at low, medium and high concentrations were 89.88%, 95.27% and 94.52% respectively, with CV less than 7.21%.PCP was stable in human samples after 6 h at room temperature, 60 h at -20 ℃, 56 days or three freeze-thaw cycles at -80 ℃; meanwhile, the processed plasma samples remained stable after being stored for 24 hours in autosampler at 8 ℃.Furthermore, PCP in human blood samples was proved to be stable after 4 h at room temperature.Conclusions The present LC-MS/MS method for the determination of PCP in human plasma was convenient, accurate, sensitive, stable, specific and reproducible and was proved to be suitable for the clinical pharmacokinetics and bioequivalence studies of PCP preparations.
Résumé
The samples of Huangqi injection (HI) were analyzed by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-TOF-MS), and both positive and negative ion modes were employed to obtain the LC-TOF-MS analysis information of chemical compounds in HI. Then the mass defect filtering (MDF) approach, which was developed based on the previously published articles, was utilized to rapidly screen the astragalosides from the obtained LC-TOF-MS data. Each screened astragaloside was confirmed by the presence of no less than 2 quasi-molecular ions. All the screened astragalosides were then tentatively assigned according to the parent ion and daughter ion information. Finally, a total of 62 astragalosides were screened and characterized from the HI samples, including 15 new detected ones. The identification results indicated that acetylation, hydrogenation, dehydrogenation, methoxylation and hydration might be the major conversion reactions involved in the formation of the astragalosides. The LC-TOF-MS-based MDF approach was proved to be a feasible and efficient tool to screen the chemical constituents in complex matrices such as herbal medicines.
Résumé
The endo-1,4-xylanase gene from Bacillus pumilus HB030 was cloned into the Pichia pastoris expression vector, pPIC9k, the recombinant plasmid was named pHBM220. The digested recombinant plasmid pHBM220 was transformed into Pichia pastoris KM71, GS115, SMD1168, respectively. The recombinant Pichia pastoris KM71 (pHBM220), GS115 (pHBM220), SMD1168 (pHBM220) secreted functional endo-1,4-xylanase, and the enzymatic activities reached 10.80IU/mL, 11.63IU/mL, 9.68IU/mL, respectively. The temperature and pH optimum for the recombinant xylanase were 60 degrees C and pH5.5, respectively.