Comparison of conventional and supported liquid extraction methods for the determination of sitagliptin and simvastatin in rat plasma by LC-ESI-MS/MS

Three extraction methods were compared for their efficiency to analyze sitagliptin and simvastatin in rat plasma by LC-MS/MS, including （1） liquid-liquid extraction （LLE）, （2） solid phase extraction （SPE） and （3） supported liquid extraction （SLE）. Comparison of recoveries of analytes with different extraction methods revealed that SLE was the best extraction method. The detection was facilitated with ion trap-mass spectrometer by multiple reactions monitoring （MRM） in a positive ion mode with ESI. The transitions monitored were m./z 441.1→325.2 for simvastatin, 408.2→235.1 for sitagliptin and 278.1→260.1 for the IS. The lower limit of quantification （LLOQ） was 0.2 ng/mL for sitagliptin and 0.1 ng/mL for simvastatin. The effective SLE offers enhanced chromatographic selectivity, thus facilitating the potential utility of the method for routine analysis of biological samples along with pharmacokinetic studies.

Direct injection HILIC-MS/MS analysis of darunavir in rat plasma applying supported liquid extraction

A novel bioanalytical method was developed and validated for the quantitative determination of darunavir（DRV） in rat plasma by employing hydrophilic interaction chromatography and tandem mass spectrometry（HILIC-MS/MS） with supported liquid extraction（SLE）.lrbesartan（IRB） was used as an internal standard（IS）.The analyte in rat plasma（200 μL） was isolated through SLE using ethyl acetate as the eluting solvent.The chromatographic separation was achieved on Luna-HILIC（250 mm × 4.6 mm,5 μm）column with a mobile phase of 0.1% of formic acid in water：acetonitrile（5：95,v/v）,at a constant flow rate of 1.0mL/min.The MS/MS ion transitions for DRV（548.1→392.0） and IS（429.2→207.1） were monitored on an ion trap mass spectrometer,operating in the multiple reaction monitoring（MRM） mode.The lower limit of quantitation（LLOQ） was 0.2 ng/mL and quantitation range was 0.2-5000 ng/mL.The method was validated for its selectivity,sensitivity,carryover,linearity,precision,accuracy,recovery,matrix effect and stability.The method was successfully applied to pharmacokinetic study in rats.

Lipase Immobilized on Magnetic Nanoparticles: A New Tool for Synthesis of Disulphide Compounds

The study describes chemo-enzymatic synthesis of organic disulphide compounds. The reaction was initiated by hydrolysis of thiol acetates using hydrolytic enzyme lipase (PPL) immobilized on to magnetic nanoparticles and subsequent formation of organic disulphide compounds. Lipase was immobilized on to the magnetic nanoparticles by co-precipitation method via epichlorohydrin chitosan cross-linking, under mild and eco-friendly conditions. The immobilized lipase enzyme exhibited broad range of substrate specificity in synthesizing disulphide compounds, which involves both intra and inter-molecular disulphide bond formation under anaerobic conditions. The disulphide compounds synthesized also show a promising antimicrobial activity.

Research and application progress of Gardenia jasminoides

Fruits of Gardenia jasminoides（Zhizi in Chinese） have been used as dietary supplement and traditional Chinese medicine for thousands of years. Recent studies on Gardenia jasminoides reveal that the extracts or the active components play an essential role in oxidative stress, inflammation, hepatoprotection,neuroprotection, anti-diabetes, antitumor and so on. Here, we reviewed G. jasminoides in the aspects of botanical identity, chemical ingredients, pharmacology and pharmacokinetics, safety and toxicity evaluation, clinical application, etc.

Current technologies to identify protein kinase substrates in high throughput

Since the discovery of protein phosphorylation as an important modulator of many cellular processes, the involvement of protein kinases in diseases, such as cancer, diabetes, cardiovascular diseases, and central nervous system pathologies, has been extensively documented. Our understanding of many disease pathologies at the molecular level, therefore, requires the comprehensive identification of substrates targeted by protein kinases. In this review, we focus on recent techniques for kinase substrate identification in high throughput, in particular on genetic and proteomic approaches. Each method with its inherent advantages and limitations is discussed.