Jialiang Guo

Exploring QSARs for 5-Lipoxygenase (5-LO) Inhibitory Activity of 2-Substituted 5-Hydroxyindole-3-Carboxylates by CoMFA and CoMSIA

A series of indole and related benzo[g]indole compounds displaying potent activities against 5‐lipoxygenase were selected to establish three‐dimensional quantitative structure–activity relationships using comparative molecular field analysis and comparative molecular similarity indices analysis methods. A training set of 37 active compounds was used to develop the models, which were then valuated by a series of internal and external cross‐validation techniques. A test set of seven compounds was used for the external validation. Models with greater than 70% predictive ability, as determined by external validation, and high internal validity (cross‐validated q2 > 0.5) have been developed. The satisfactory comparative molecular field analysis model predicted a q2 value of 0.779 and an r2 value of 0.957 and revealed that electrostatic and steric properties play a significant role in potency. The best comparative molecular similarity indices analysis model, based on a combination of steric, hydrophobic, and H‐bond donor effects, predicted a q2 value of 0.816 and an r2 value of 0.953. The models were graphically interpreted using comparative molecular field analysis and comparative molecular similarity indices analysis contour plots that provided insight into the structural requirements for increasing the activity of a compound. The results obtained from this study provide a solid basis for future rational design of more active 5‐lipoxygenase inhibitors.

Preparation and application of novel zwitterionic monolithic column for hydrophilic interaction chromatography.

A novel zwitterionic hydrophilic porous monolithic stationary phase was prepared based on the thermal-initiated copolymerization of N,N-dimethyl-N-(3-methacryl-amidopropyl)-N-(3-(sulfopropyl)ammonium betaine and ethylene glycol dimethacrylate. A typical hydrophilic separation mechanism was observed at a highly organic mobile phase (ACN >60%) on this optimized zwitterionic hydrophilic interaction chromatography (HILIC) monolithic stationary phase. Good permeability, stability, and column efficiency were observed on the final monolithic column. Additionally, a weak electrostatic interaction for charged analytes was confirmed in analysis of six benzoic acids by studying the influence of mobile phase pH and salt concentration on their retention behaviors on the obtained zwitterionic HILIC monolithic column. The optimized zwitterionic HILIC monolith exhibited good selectivity for a range of polar test analytes.

A facile and efficient one-step strategy for the preparation of β-cyclodextrin monoliths

A novel, facile, and efficient one-step copolymerization strategy was developed for the preparation of β-cyclodextrin (β-CD) methacrylate monolithic columns using click chemistry. The novel mono-(1H-1,2,3-triazol-4-ylmethyl)-2-methylacryl-β-CD monomer was synthesized by a click reaction between propargyl methacrylate and mono-6-azido-β-CD, and then monolithic columns were prepared through a one-step in situ copolymerization of the mono-(1H-1,2,3-triazol-4-ylmethyl)-2-methylacryl-β-CD monomer and ethylene dimethacrylate. The physicochemical properties and column performance of the fabricated monolithic columns were characterized by elemental analysis, SEM, and micro-HPLC. Satisfactory column permeability, efficiency, and separation performance were obtained for the optimized poly(mono-(1H-1,2,3-triazol-4-ylmethyl)-2-methylacryl-β-CD-co-ethylene dimethacrylate) monolithic columns. Additionally, typical hydrophilic interaction chromatography retention behavior was observed on the monoliths at high acetonitrile content in the mobile phase. Although the enantioselectivity of our monolithic columns did not meet the level of other reported β-CD monolithic columns, this one-step strategy based on click chemistry still provides an interesting and effective model as it offers the possibility to easily prepare related novel CD methacrylate monoliths through a one-step copolymerization strategy.

Comparative evaluation of a one-pot strategy for the preparation of β-cyclodextrin-functionalized monoliths: Effect of the degree of amino substitution of β-cyclodextrin on the column performance.

To further evaluate the feasibility and applicability of the one-pot strategy in monolithic column preparation, two novel β-cyclodextrin-functionalized organic polymeric monoliths were prepared using two β-cyclodextrin derivatives, i.e. mono(6-amino-6-deoxy)-β-cyclodextrin and heptakis(6-amino-6-deoxy)-β-cyclodextrin. In this improved method, mono(6-amino-6-deoxy)-β-cyclodextrin or heptakis(6-amino-6-deoxy)-β-cyclodextrin reacted with glycidyl methacrylate to generate the corresponding functional monomers and were subsequently copolymerized with ethylene dimethacrylate. The polymerization conditions for both monoliths were carefully optimized to obtain satisfactory column performance with respect to column efficiency, reproducibility, permeability, and stability. The obtained poly(glycidyl methacrylate-mono(6-amino-6-deoxy)-β-cyclodextrin-co-ethylene dimethacrylate) and poly(glycidyl methacrylate-heptakis(6-amino-6-deoxy)-β-cyclodextrin-co-ethylene dimethacrylate) monoliths exhibited a uniform structure, good permeability, and mechanical stability as indicated by scanning electron microscopy and micro-high-performance liquid chromatography experimental results. Because of the probable existence of multi-glycidyl methacrylate linking spacers on the poly(glycidyl methacrylate-heptakis(6-amino-6-deoxy)-β-cyclodextrin-co-ethylene dimethacrylate) monolith, the effect of the ratio of glycidyl methacrylate/heptakis(6-amino-6-deoxy)-β-cyclodextrin was especially studied, and satisfactory reproducibility could still be achieved by strictly controlling the composition of the polymerization mixture. To investigate the effect of the degree of amino substitution of β-cyclodextrin on column performance, a detailed comparison of the two monoliths was also carried out using series of analytes including small peptides and chiral acids. It was found that the β-cyclodextrin-functionalized monolith with mono-glycidyl methacrylate linking spacers demonstrated better chiral separation performance than that with multi-glycidyl methacrylate linking spacers.

A novel mixed phospholipid functionalized monolithic column for early screening of drug induced phospholipidosis risk.

Drug-induced phospholipidosis (PLD) is characterized by the excessive accumulation of phospholipids, resulting in multilamellar vesicle structure within lysosomes. In the present study, a novel mixed phospholipid functionalized monolithic column was developed for the first time through a facile one-step co-polymerization approach. The phospholipid composition of the monolith can be adjusted quantitatively and accurately to mimic the mixed phospholipid environment of different biomembranes on a solid matrix. The mixed phospholipid functionalized monolith as a promising immobilized artificial membrane technique was used to study drug-phospholipid interaction. Scanning electron microscopy, elemental analysis, FT-IR spectra, ζ-potential analysis and micro-HPLC were carried out to characterize the physicochemical properties and separation performance of the monolith. Mechanism studies revealed that both hydrophobic and electrostatic interactions play an important role in the retention of analytes. The ratio of their contributions to retention can be easily manipulated by adjusting the composition of the mixed phospholipids, in order to better mimic the interaction between drugs and cell membrane. The obtained mixed phospholipid functionalized monolithic columns were applied to the screening of drug-induced PLD potency. Data from 79 drugs on the market demonstrated that the chromatographic hydrophobicity index referring to the mixed phospholipid functionalized monolith at pH 7.4 (CHI IAM7.4) for the selected drugs were highly correlated with the drug-induced PLD potency data obtained from other in vivo or in vitro assays. Moreover, the effect of the acidic phospholipid phosphatidylserine proportion on prediction accuracy was also investigated. The monolith containing 20% phosphatidylserine and 80% phosphatidylcholine exhibited the best prediction ability for the drug-induced PLD potency of the tested compounds. This research has led to the successful development of a novel and facile approach to prepare a mixed phospholipids functionalized monolith, which offers a reliable, cost-effective and high-throughput screening tool for early prediction of the PLD potency of drug candidates.

Influence of the linking spacer length and type on the enantioseparation ability of β-cyclodextrin functionalized monoliths.

In order to investigate the effect of the linking spacer on the enantioseparation ability of β-cyclodextrin (β-CD) functionalized polymeric monoliths, three β-CD-functionalized organic polymeric monoliths with different spacer lengths were prepared by using three amino-β-CDs, i.e. mono-6-amino-6-deoxy-β-CD, mono-6-ethylenediamine-6-deoxy-β-CD, mono-6-hexamethylenediamine-6-deoxy-β-CD, as starting materials. These amino-β-CDs reacted with glycidyl methacrylate to produce functional monomers which were then copolymerized with ethylene dimethacrylate. The enantioseparation ability of the three monoliths was evaluated using 14 chiral acidic compounds, including mandelic acid derivatives, nonsteroidal anti-inflammatory drugs, N-derivatized amino acids, and chiral herbicides under optimum chromatographic conditions. Notably, the poly(GMA-NH2-β-CD-co-EDMA) column provides higher enantioresolution and enantioselectivity than the poly(GMA-EDA-β-CD-co-EDMA) and poly(GMA-HDA-β-CD-co-EDMA) columns for most tested chiral analytes. Furthermore, the enantioseparation performance of triazole-linker containing monoliths was compared to that of ethylenediamine-linker containing monoliths. The results indicate that the enantioselectivity of β-CD monolithic columns is strongly related to the length and type of spacer tethering β-CD to the polymeric support.

Recent developments in cyclodextrin functionalized monolithic columns for the enantioseparation of chiral drugs

The use of monolithic supports containing cyclodextrins (CDs) or their derivatives as chiral stationary phases (CSPs) has drawn much attention in the field of enantioseparations. The present review summarized the recent developments in CD functionalized monolithic columns. After introducing their classification in Section 1, various strategies applied to the preparation of the three types of CD functionalized monoliths, i.e. silica based monoliths, organic polymer based monoliths and organic-silica based hybrid monoliths, are thoroughly summarized in Section 2. Particularly, three different preparation strategies for covalently immobilizing CDs onto monoliths, including multi-step strategy, single-step strategy and one-pot strategy, are discussed. In the last section, the applications of CD functionalized monoliths in chiral separation of pharmaceuticals are highlighted.

Insight into the Interactions between Novel Isoquinolin-1,3-Dione Derivatives and Cyclin-Dependent Kinase 4 Combining QSAR and Molecular Docking

Several small-molecule CDK inhibitors have been identified, but none have been approved for clinical use in the past few years. A new series of 4-[(3-hydroxybenzylamino)-methylene]-4H-isoquinoline-1,3-diones were reported as highly potent and selective CDK4 inhibitors. In order to find more potent CDK4 inhibitors, the interactions between these novel isoquinoline-1,3-diones and cyclin-dependent kinase 4 was explored via in silico methodologies such as 3D-QSAR and docking on eighty-one compounds displaying potent selective activities against cyclin-dependent kinase 4. Internal and external cross-validation techniques were investigated as well as region focusing, bootstraping and leave-group-out. A training set of 66 compounds gave the satisfactory CoMFA model (q 2 = 0.695, r 2 = 0.947) and CoMSIA model (q 2 = 0.641, r 2 = 0.933). The remaining 15 compounds as a test set also gave good external predictive abilities with r 2 pred values of 0.875 and 0.769 for CoMFA and CoMSIA, respectively. The 3D-QSAR models generated here predicted that all five parameters are important for activity toward CDK4. Surflex-dock results, coincident with CoMFA/CoMSIA contour maps, gave the path for binding mode exploration between the inhibitors and CDK4 protein. Based on the QSAR and docking models, twenty new potent molecules have been designed and predicted better than the most active compound 12 in the literatures. The QSAR, docking and interactions analysis expand the structure-activity relationships of constrained isoquinoline-1,3-diones and contribute towards the development of more active CDK4 subtype-selective inhibitors.

Effect of the crosslinker type on the enantioseparation performance of β-cyclodextrin functionalized monoliths prepared by the one-pot approach.

Low column efficiency for enantioseparations in capillary liquid chromatography (CLC) is a major problem commonly encountered with β-cyclodextrin (β-CD) functionalized polymer-based monoliths. In order to investigate the effect of the crosslinker type on enantioseparation performance, three commonly used crosslinkers, i.e. 1,4-bis(acryloyl)piperazine (PDA), ethylene dimethacrylate (EDMA) and N,N-methylenebisacrylamide (MBA), were copolymerized using the one-pot approach with glycidyl methacrylate-mono-6-amino-6-deoxy-β-CD (GMA-NH2-β-CD) as functional monomer. The three monolithic columns, including poly(GMA-NH2-β-CD-co-PDA) and poly(GMA-NH2-β-CD-co-MBA), as well as the previously reported column poly(GMA-NH2-β-CD-co-EDMA) were systematically compared with respect to morphology, permeability, β-CD density, retention mechanism and efficiency. The enantioseparation ability of each column was evaluated using 14 chiral compounds, including mandelic acid derivatives, profens, N-derivatized amino acids, and herbicides, as test substances. The β-CD-functionalized monolith with MBA as crosslinker was found to exhibit higher polarity, higher column efficiency and better enantioseparation performance than those with PDA or EDMA as crosslinker.

Three-dimensional quantitative structure-activity relationships of pyrrolopyridinone as cell division cycle kinase inhibitors by CoMFA and CoMSIA

Seventy-five 1,5,6,7-tetrahydro-pyrrolo[3,2-C]pyridinone derivatives displaying potent activities against Cdc7 kinase were selected to establish 3D-QSAR models using CoMFA and CoMSIA methods. Internal and external cross-validation techniques were investigated as well as some measures including region focusing, progressive scrambling, bootstraping and leave-group-out. The satisfactory CoMFA model predicted a q2 value of 0.836 and an r2 value of 0.950, indicating that electrostatic and steric properties play a significant role in potency. The best CoMSIA model, based on a combination of steric, electrostatic and H-bond acceptor effects, predicted a q2 value of 0.636 and an r2 value of 0.907. The models were graphically interpreted using contour plots which provided insight into the structural requirements for increasing the activity of a compound. The final 3D-QSAR results could be used for rational design of potent inhibitors against Cdc7 kinase.