A novel monolithic column incorporated with Schiff base network-1 (SNW-1) was prepared for in-tube solid phase microextraction (SPME) of antiepileptic drugs . The SNW-1 nanoparticles was synthesized by a solvent thermal method and embedded in the poly(glycidyl methacrylate-ethylene glycol dimethacrylate) (GMA-EGDMA) monolithic column by in situ polymerization. The amount of SNW-1 in polymerization solution for preparation of monolithic column was optimized. Fourier transform infrared spectrometry and scanning electron microscope were used to characterize the obtained monolithic column. The SNW-1-monolithic column was connected to the high-performance liquid chromatography (HPLC) system and applied for online extraction and analysis of antiepileptic drugs. The extraction conditions including sample solution flow rate , desorption time, acetonitrile content, pH of sample solution and sample volume were investigated. Under optimal conditions, the proposed SPME-HPLC method showed high extraction efficiency, good linearity, low limits of detection (0.2 ng/mL) and good repeatability (relative standard deviations < 2.41%). This method was also applied to the analysis of antiepileptic drugs in human plasma samples and the recoveries were in the range of 88.6–106.1% with RSDs less than 3.51%.
Lanteng Wang,Jin Wang,Ang Zhang,Xin-an Huang,Hongtao Lei
A growing number of β -agonists are illegally using for reducing animal fat deposition in animals, but the development of analytical methods always lags behind the emergence of new illegal compounds. Therefore, class specificity antibody-based immunoassays that can detect a great many β -agonists are important for timely supervision. In this study, a competitive inhibition enzyme-linked immunosorbent assay (ciELISA) based on a clenbuterol monoclonal antibody was developed to recognize 23 β -agonists and analogues. Holographic and three-dimensional quantitative structure–activity relationship (HQSAR and 3D QSAR) revealed that there are two critical binding epitopes on β -agonist hapten affecting antibody specificity, and these epitopes have been further validated using a ractopamine antibody with narrow specificity. Tert -butyl at C-2′ epitope is needed to generate class specific antibodies, and different characteristics of substituents at benzene ring epitope would adjust antibody specificity. This investigation could provide reference for future design of β -agonist haptens.
Identification of new α -glucosidase ( α -Glu) inhibitors from natural sources is very important to the management of type 2 diabetes. In this work, liquiritigenin (LTG), a flavonoid compound derived from liquorice, was found to have excellent inhibition of α -Glu (IC 50 = 27.91 ± 3.48 μM) in a mixed manner. LTG reduced the endogenous fluorescence of α -Glu in a static mode by spontaneously forming stable complexes with the α -Glu-substrate through hydrophobic forces and hydrogen bonding. LTG decreased the α -helix and β -sheet contents of α -Glu while increasing the β -turn and random coil contents. Computer simulation showed that LTG interacted non-covalently with Gly161, Glu422, Glu429, and Asn235 residues of α -Glu, causing structural unfolding of the enzyme, which affected the substrate-enzyme interaction and ultimately reduced the release of the product. While acarbose, a competitive inhibitor of α -Glu, spontaneously hydrogen-bonded Tyr158, His280, Asp242, and Asp352 residues of the LTG− α -Glu complex. Moreover, a combination of LTG (6.00 μM) and acarbose (30.00 μM) had a remarkable synergistic inhibition on α -Glu, which may be because LTG made the structure of α -Glu loosening and reduced its catalytic activity through allosteric effect. And the occupation of the active cavity by acarbose may lead to a conformational change in the LTG− α -Glu complex, which effectively hindered the binding between the substrate and α -Glu. These findings may offer a new theoretical foundation for the development of LTG as a glucose-lowering ingredient in functional foods.
危险品化学品经营许可证（带存储）