Screening of glycoside isomers in P. scrophulariiflora using ionic liquid‐based ultrasonic‐assisted extraction and ultra‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

A powerful ionic liquid‐based ultrasonic‐assisted extraction (ILUAE) method combined with ultra‐performance liquid chromatography coupled to electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (UPLC/ESI‐QTOFMSⁿ) was employed in the rapid simultaneous screening of iridoid glycosides, phenylethanoid glycosides, and cucurbitacin glycosides from P. scrophulariiflora. The ILUAE procedure was optimized over several ultrasonic parameters, including the ultrasonic power, concentration of the ionic liquid, and solid–liquid ratio. A comparison with conventional heat‐reflux extraction and regular UAE demonstrated that the optimized approach yielded a high extraction efficiency (Picroside I, 2.84%; Picroside II, 3.57%; 6‐O‐E‐feruloyl catalpol, 2.20%) within a short extraction time of 30 min. Negative ion mode ESI‐QTOFMS² analysis of the fragmentation reactions of the [M–H]^– ions was conducted to characterize the diagnostic ions related to the glycosyl moieties, aglycone units, and the type and substituted position of the ester groups. Interestingly, the positional isomers of the iridoid glycosides could be easily discriminated based on the characteristic ions. A total of 15 glycosides, including three groups of iridoid glycoside isomers and two groups of phenylethanoid glycoside isomers, were conveniently identified within 13.5 min. Moreover, 6'‐O‐vanilloyl catalpol was identified in P. scrophulariiflora for the first time. The method developed here was further validated by measuring the recovery, correlation coefficient (R²), and reproducibility (RSD, n = 5) of three iridoid glycosides: 89.60%–109.02%, 0.9991–0.9998, and 0.93%–1.44%, respectively. This study demonstrated the capabilities of ILUAE combined with UPLC/ESI‐QTOFMSⁿ for the rapid screening of glycosides in P. scrophulariiflora. This method offers an approach to similar studies on other natural plants. Copyright © 2012 John Wiley & Sons, Ltd.     

Determination of pseudo‐ginsenoside GQ in human plasma by high performance liquid chromatography–tandem mass spectrometry

A specific, sensitive and rapid method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC‐MS/MS) was developed for the determination of pseudo‐ginsenoside GQ in human plasma. Liquid–liquid extraction was used to isolate the analyte from biological matrix followed by injection of the extracts onto a C₈ column with isocratic elution. Detection was carried out on a triple quadrupole tandem mass spectrometer (API‐4000 system) in multiple reaction monitoring mode using negative electrospray ionization. The mobile phase consisted of methanol–10 mm ammonium acetate (90:10, v/v) and the flow rate was 0.3 mL/min. The method was validated over the concentration range of 5.0–5000.0 ng/mL for plasma. Inter‐ and intra‐day precisions (relative standard deviation) were all within 15% and the accuracy (relative error) was ≤9.4%. The lower limit of quantitation was 5.0 ng/mL. The pseudo‐ginsenoside GQ was stable after 8 h at room temperature, 24 h at autosampler and three freeze–thaw cycles (from ?30 to 25 °C). The method was successfully applied to the pharmacokinetic study of pseudo‐ginsenoside GQ in healthy Chinese volunteers. Copyright © 2013 John Wiley & Sons, Ltd.     

Combination of FASP and fully automated 2D‐LC‐MS/MS allows in‐depth proteomic characterization of mouse zymogen granules

Zymogen granule (ZG) constituents play important roles in pancreatic injury and disease. In previous studies, proteomic analyses with rat zymogen granules were separated by two‐dimensional gel electrophoresis or one‐dimensional SDS–PAGE, followed by in‐gel tryptic digestion. In order to overcome the disadvantage of in‐gel digestion and to carry out further in‐depth proteomic analysis of the zymogen granules, in this study, by combining a filter‐aided sample preparation method and fully automated 2D‐LC‐MS/MS technique, 800 ZG proteins were identified with at least two unique peptides for each protein, 75% of which have not been previously reported. The identified proteins revealed broad diversity in protein identity and function. This is the largest dataset of ZG proteome, and also the first dataset of the mouse ZG proteome, which may help elucidate on the molecular architecture of ZGs and their functions. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and mesomorphic properties of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoates

A series of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoate liquid crystals have been synthesized. Their phase transition temperatures have been measured by optical polarizing microscopy and confirmed by DSC. The results show that a highly fluorinated terminal chain impairs mesomorphic properties.     

Cyano terminated tolane compounds for polymer dispersed liquid crystal application: relationship between cyano terminated tolane based molecular structures and electro-optical properties

ABSTRACT

The structures of the liquid crystal (LC) molecules have a key role in impacting the electro-optical performance of a polymer dispersed liquid crystal (PDLC) film. In this paper, the relationship between the LC molecular structures and the electro-optical properties of PDLC films is investigated based on an unexplored cyano-terminated tolane compounds (CTTCs) doped E8 LCs/UV polymers system. Due to the high polarity of CTTCs, LCs doped with the cyano-terminated tolane (CTT) molecules exhibit high birefringence and large positive dielectric anisotropy. On the whole, PDLC films doped with the CTT molecules exhibit a lower driving voltage than that doped with the pure E8. More excitingly, PDLC films based on CTT molecules with larger length-to-width ratio and longer conjugated system show higher contrast ratio (CR) and faster response time. Eventually, the mechanism of the effects of CTT-based molecular structures and the relationship between the electro-optical performance of PDLC films and CTT molecules are illustrated. This work paves a new way for optimising the electro-optical properties of PDLC films.     

Synthesis and properties of reactive liquid crystal monomers and side-chain liquid crystalline polymers

Two nematic liquid crystal (LC) monomers containing double bonds in the side chain were designed and synthesised. Length of the side groups varied from 1 to 2 methylene units. The side-chain polymers were synthesised by hydrosilylation reaction. The molecular structures of the intermediates and the LC monomers were characterised by Fourier transform infrared, elemental analysis and nuclear magnetic resonance spectroscopy. The thermal phase behaviour of the monomers and polymers were investigated by differential scanning calorimetry and polar optical microscopy coupled with hot stage. The LC monomers showed only one nematic mesophase in the cooling process. And, the two polymers exhibit an enantiotroppic nematic mesophase either in the heating or in the cooling process.