An Efficient UPLC-MS/MS Method for the Determination of Pyrroloquinoline Quinone in Rat Plasma and Its Application to a Toxicokinetic Study.

Pyrroloquinoline quinone (PQQ) is a powerful antioxidant coenzyme existing in diet, benefiting growth, development, cognition function, and the repair of damaged organs. However, a method for detecting PQQ in vivo was rarely described, limiting the research on the bioanalysis and metabolic properties of PQQ. In this study, a novel, simple, and efficient ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to quantify the concentration of PQQ in rat plasma. Detection through mass spectrometry was operated by multiple reaction monitoring (MRM) in negative electrospray ionization mode with ion transitions m/z 328.99→197.05 for PQQ and m/z 280.04→195.04 for the internal standard. The calibration curves were linear up to 10,000 ng/mL, with a lower limit of quantitation of 10 ng/mL. Inter-run and intra-run precision ranged from 1.79% to 10.73% and accuracy ranged from -7.73% to 7.30%. The method was successfully applied to a toxicokinetic study in Sprague-Dawley rats after the oral administration of PQQ disodium salt at doses of 250 mg/kg, 500 mg/kg, and 1000 mg/kg. The toxicokinetic parameters were subsequently analyzed, which may provide valuable references for the toxicokinetic properties and safety evaluation of PQQ.

Supercritical fluid chromatography-a technical overview and its applications in medicinal plant analysis: an update covering 2012-2018.

Medicinal plants with complex matrices are endowed with a wide scope of biological activities. The separation, quantification, characterization and purification of bioactive components from herbal medicine extracts have always challenged analysts. Fortunately, the advancement of various emerging techniques has provided potent support for improving the method selectivity, sensitivity and run speeds in medicinal plant analyses. In recent years, the advent of new-generation supercritical fluid chromatography (SFC) instruments and a wide diversity of column chemistries, coupled with the intrinsic technical features of SFC, have made it an alternative and prominent analytical platform in the medicinal plant research area. This work aims to give a comprehensive overview of the fundamentals, technical advancement and investigating parameters of SFC in combination with three prevalent detectors. Moreover, the latest research progress of SFC applications in medicinal plant analyses is illuminated, with focus on herbal medicine-related SFC papers on the analytical and preparative scale that were published during the period of 2012 to December 2018. The most relevant applications were classified based on the constituents to be analysed. As for the respective research cases, analytical protocols and data processing strategies were provided, along with the indicated restrictions or superiority of the method; thus, the current status of SFC in medicinal plant analysis was presented.

Determination of 22 alternative plasticizers in wrap film by solid phase extraction and ultra-high performance supercritical fluid chromatography-tandem mass spectrometry.

A rapid, accurate and novel analytical method based on ultra-high performance supercritical fluid chromatography-tandem mass spectrometry for determination of 22 alternative plasticizers in wrap film was developed. Instrumental analysis and sample preparation procedures were systematically optimized. The targets were separated on Torus 1-AA column (100 mm × 3 mm, 1.7 µm). Mobile phase A was supercritical carbon dioxide, and mobile phase B was ethanol/methanol (7:3, v/v) containing 0.1% formic acid and 0.5 mM ammonium acetate. Gradient elution was performed. The analytes were extracted by 10 mL n-hexane/dichloromethane (1:1, v/v), and further purified on silica solid phase extraction cartridges. The analytes were quantified by ultra-high performance supercritical fluid chromatography-tandem mass spectrometry with electrospray ionization source, and detection was performed on multiple reaction monitoring mode. Two commercially available isotopically-labelled internal standards were used for quantification calibration, and analytes were divided into two groups according to the more appropriate internal standards (chemistry similarity, closeness of retention time). Method validation was performed in terms of recovery, repeatability, linearity, sensitivity and matrix effect. Linearity was assessed using matrix-matched standard calibration. Satisfactory linearity (r2 ≥ 0.995), intra-day precision (RSDs ≤ 9.6%), inter-day precision (RSDs ≤ 10.9%), recovery (75.6-124.5%) as well as good selectivity was observed. The limits of detection were 0.04-10 µg/kg, while the limits of quantification were 1.0-50 µg/kg. Most targets did not show significant matrix effect. Validation results verified that the proposed method was efficient, rapid and sensitive. Eventually it was successfully applied to food wrap film analysis, and results indicated that DEHA, ATBC, DBA and TnBP were the most frequently detected plasticizers in wrap film samples,which was worthy of attention.

[Construction expression and biologic activity of recombinant human sCR1 eucaryotic cell].

AIM: To express human soluble complement receptor type 1(sCR1)protein using ferment cell secreting type carrier and study the extraorgan biologic activity of recombinant human sCR1 fusion protein. METHODS: Total human RNA was extracted from peripheral blood. The full length cDNA of human sCR1 gene was obtained by RT-PCR and them, cloned into Pichia pastoris eukaryotic expression vector pPIC9k to construct the recombinant plasmid pPIC9k-sCR1 containing human sCR1.After identified by DNA sequencing, the recombinant plasmid pPIC9k-sCR1 was transformed into Pichia pastoris SMD1168. The ferment cell line of the recombinant sCR1 which was chosen by G418 resistance was identified by PCR, After methanol induction, the expressed protein products were verified by SDS-PAGE and Western blot, purified by Ni(2+)-NTA agarose affinity chromatography, and its biologic activity was identified. RESULTS: The obtained Pichia pastoris secretion type yeast carrier pPIC9k-sCR1 was chosen by G418 and identified by PCR to get a highly copied and integral recombinant ferment cell line. The recombinant human sCR1 fusion protein was expressed by yeast cells containing pPIC9k-sCR1 induced by methanol. It was a protein band about M(r) 31 000 in gel, which could be identified by CD35 of anti-sCR1 protein monoclonal antibody with Western blotting technique. The highly purified sCR1 fusion protein and its biologic activity were detected obtained by Ni(2+)-NTA agarose affinity chromatography. CONCLUSION: The recombinant human sCR1 fusion protein can be highly expressed in the Pichia pastoris expression system, which resembles the human natural protein's antigenicity and biologic activity.