•13 compounds as topoisomerase IIα inhibitors were designed and synthesized.•Evaluated for topo I and IIα inhibitory activity, antiproliferative activity.•Molecular docking studies were investigated.•Compounds showed selective topoisomerase IIα inhibition.•5b showed best antiproliferative activity, topoisomerase IIα inhibitory activity.A new series of thirteen N-(carbobenzyloxy)-l-phenylalanine and N-(carbobenzyloxy)-l-aspartic acid-β-benzyl ester compounds were synthesized and evaluated for antiproliferative activity against four different human cancer cell lines: cervical cancer (HeLa), lung cancer (A549), gastric cancer (MGC-803) and breast cancer (MCF-7) as well as topoisomerase I and IIα inhibitory activity. Compounds (5a, 5b, 5e, 8a, 8b) showed significant antiproliferative activity with low IC50 values against the four cancer cell lines. Equally, compounds 5a, 5b, 5e, 5f, 8a, 8d, 8e and 8f showed topoisomerase IIα inhibitory activity at 100 μM with 5b, 5e, 8f exhibiting potential topoisomerase IIα inhibitory activity compared to positive control at 100 μM and 20 μM, respectively. Conversely compounds 5e, 5f, 5g and 8a showed weaker topoisomerase I inhibitory activity compared to positive control at 100 μM. Compound 5b exhibited the most potent topoisomerase IIα inhibitory activity at low concentration and better antiproliferative activity against the four human cancer cell lines. The molecular interactions between compounds 5a–5g, 8a–8f and the topoisomerase IIα (PDB ID: 1ZXM) were further investigated through molecular docking. The results indicated that these compounds could serve as promising leads for further optimization as novel antitumor agents.Download high-res image (73KB)Download full-size image

In this study, new metal–organic frameworks (MOFs) nanocrystals modified SiO2 core–shell microspheres were designed with cationic ionic liquids (ILs) 1,3-bis(4-carboxybutyl)imidazolium bromide (ILI) as organic ligands. By further adjustment the growth cycles, the new ILI-01@SiO2 core–shell stationary phase was facilely fabricated. The developed stationary phase was respectively characterized via element analysis, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry. Because the introduction of cationic imidazolium-based ILs ILI for fabrication of the MOFs nanocrystals shell, the new stationary phase exhibits the retention mechanism of hydrophilic interaction liquid chromatography (HILIC). Many polar samples, such as amides, vitamins, nucleic acid bases, and nucleosides, were utilized to investigate the performance of the prepared ILI-01@SiO2 column. Compared to the conventional aminosilica column, the new ILI-01@SiO2 column displays high separation selectivity in a shorter separation time. Furthermore, the new ILI-01@SiO2 column was also used for detection of illegal melamine addition in the baby formula. All the above results demonstrate the new ILI-01@SiO2 core–shell stationary phase is of good potentials for high-selectivity separation the polar samples.Keywords: core−shell stationary phase; high-efficiency separation; HILIC; ionic liquids; MOFs nanocrystals

•The recently reported particle-based mixed-mode stationary phases are summarized.•Monolithic-based mixed-mode stationary phases are reviewed.•The mixed-mode stationary phases are classified based on the high-performance liquid chromatography (HPLC) modes.•This study emphasizes the preparation methods and further applications.Chromatographic stationary phase is the core of high-performance liquid chromatography (HPLC) system. Thereinto, the development of novel stationary phases with high separation efficiency and excellent selectivity has always been the focus of the study. Mixed-mode stationary phases have been proved to be with the merits of high separation selectivity, remarkably high loading capacity, and high separation efficiency. In this study, the recently reported particle-based mixed-mode stationary phases are summarized, especially for those reported in the recent 5 years. These stationary phases are classified based on the HPLC modes, emphasizing the preparation methods and further applications. Furthermore, the recently reported monolithic-based mixed-mode stationary phases for HPLC are also included.

In this study, a novel type of pyridinium-based tags, 1-[3-[(2-iodo-1-oxoethyl)amino]propyl]-4-methylpyridinium bromide (IMP) and 1-[3-[(2-iodo-1-oxoethyl)amino]propyl]-4-propylpyridinium bromide (IPP), were designed, synthesized, and applied to the derivatization of thiol-containing peptides. With model peptides as the sample, the labeling efficiency and the stability of the peptide derivatives were investigated. The results indicate that nearly 100% derivatization yield was achieved with the developed tags and the peptide derivatives were stable at room temperature for at least one week. Furthermore, improved ionization efficiency and increased charge states were achieved via both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS) and electrospray ionization (ESI) MS, of which IPP exhibited the more obvious improvement of ionization efficiency. Further analysis of tryptic digests of bovine serum albumin (BSA) and α-transferrin, showed that increased identification efficiency of the thiol-containing peptides was achieved by combination with IMP or IPP derivatization. For example, the identification efficiency of the thiol-containing peptides of α-transferrin increased more than 42% upon combination with the IMP or IPP derivatives. We anticipate the novel tags are promising for highly efficient thiol-containing peptide identification in proteome research, especially for low concentrations.

In this study, a novel imidazolium embedded C8 hybrid monolithic column based on polyhedral oligomeric silsesquioxane (POSS) was developed. With 1-vinyl-3-octylimidazolium bromide (VOI) as functional monomer, POSS-methacryl substituted (POSS-MA) as cross-linker, and azodiisobutyronitrile (AIBN) as thermal initiator, the monolithic column was facilely prepared via a “one-pot” process. The prepared column was characterized by scanning electron microscopy, Fourier transform infrared spectrometry, thermogravimetric analysis, and elemental analysis, respectively. Due to the introduction of VOI to the POSS-based monolith, the column efficiency reached 124000 theoretical plates per m for separation of alkylbenzenes, outperforming the previously reported pentafluorobenzyl imidazolium bromide modified POSS hybrid monolithic column. Furthermore, high-efficiency separation of polycyclic aromatic hydrocarbons, aromatic amines, and even phenolic isomers was also achieved. All these results suggest the potential merits of the prepared hybrid monolithic column for separation of small molecules.

A novel imidazolium-embedded N,N-dimethylaminopropyl-functionalized silica-based stationary phase (Sil-ImCl) was prepared and further used for hydrophilic interaction/reversed-phase mixed-mode chromatography. The Sil-ImCl stationary phase was respectively characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, and element analysis. A variety of hydrophilic or hydrophobic compounds were used to evaluate the retention mechanisms of the developed stationary phase, and the effects of buffer salt concentration and pH of mobile phase on the retention of these compounds were also investigated. The developed stationary phase was successfully applied for separation of nucleosides and nucleic acid bases, water-soluble vitamins, phenols, and positional isomers. Moreover, simultaneous separation of polar and nonpolar compounds was also achieved with high resolution, outperforming the commercially available C8 column and amino column. Furthermore, the Sil-ImCl stationary phase has been successfully applied for separation of secondary metabolites of Hansfordia sinuosae. All these results demonstrate that the Sil-ImCl stationary phase might be promising for separation of complex polar and nonpolar compounds with high efficiency, especially in biological industry.

•The recent reported tags for high efficiency analysis of peptides by mass spectrometry are reviewed.•These tags are categorized based on their target reactive groups on peptides.•Tags for analysis of post-translational modifications have been included.•A brief introduction of their applications for peptide analysis is presented.Chemical derivatization is a very promising technique for improving analysis of peptides by mass spectrometry (MS). Thereinto, development of novel tags compatible with MS and/or MS/MS has always been the focus point of study. In this review, the recent reported tags for derivatization of thiol groups of cysteine, carboxyl groups, and amino groups on peptides as well as peptides with post-translational modifications (PTMs) are summarized. Moreover, the tags used for derivatization of glycans or oligosaccharides released from glycoproteins are also reviewed.