WIDE SENSE STABILITY OF COMPLEX SYSTEMS OF DIFFERENTIAL EQUATIONS OF ARBITRARY DIMENSION

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Controlling retention, selectivity and magnitude of EOF by segmented monolithic columns consisting of octadecyl and naphthyl monolithic segments--applications to RP-CEC of both neutral and charged solutes

Monolithic capillaries made of two adjoining segments each filled with a different monolith were introduced for the control and manipulation of the electroosmotic flow (EOF), retention and selectivity in reversed phase-capillary electrochromatography (RP-CEC). These columns were called segmented monolithic columns (SMCs) where one segment was filled with a naphthyl methacrylate monolith (NMM) to provide hydrophobic and π-interactions, while the other segment was filled with an octadecyl acrylate monolith (ODM) to provide solely hydrophobic interaction. The ODM segment not only provided hydrophobic interactions but also functioned as the EOF accelerator segment. The average EOF of the SMC increased linearly with increasing the fractional length of the ODM segment. The neutral SMC provided a convenient way for tuning EOF, selectivity and retention in the absence of annoying electrostatic interactions and irreversible solute adsorption. The SMCs allowed the separation of a wide range of neutral solutes including polycyclic aromatic hydrocarbons (PAHs) that are difficult to separate using conventional alkyl-bonded stationary phases. In all cases, the k' of a given solute was a linear function of the fractional length of the ODM or NMM segment in the SMCs, thus facilitating the tailoring of a given SMC to solve a given separation problem. At some ODM fractional length, the fabricated SMC allowed the separation of charged solutes such as peptides and proteins that could not otherwise be achieved on a monolithic column made from NMM as an isotropic stationary phase due to the lower EOF exhibited by this monolith.     

Tracing pore-space heterogeneities in X-type zeolites by diffusion studies

Pore-space homogeneity of zeolite NaX was probed by pulsed field gradient (PFG) NMR diffusion studies with n-butane as a guest molecule. At a loading of 0.75 molecules per supercage, a wide spectrum of diffusivities was observed. Guest molecules in the (well-shaped) zeolite crystallites were thus found to experience pore spaces of quite different properties. After loading enhancement to 3 molecules per supercage, however, molecular propagation ideally followed the laws of normal diffusion in homogeneous media. At sufficiently high guest concentrations, sample heterogeneity was thus found to be of no perceptible influence on the guest mobilities anymore.     

On a fully nonlinear degenerate parabolic system modeling immiscible gas–water displacement in porous media

In this paper, we are interested in the simultaneous flow of two immiscible fluid phases within a porous medium. We consider a two-phase flow model where the fluids are immiscible and there is no mass transfer between the phases. The medium is saturated by compressible/incompressible phase flows. We study the gas–water displacement without simplified assumptions on the state law of gas density. We establish an existence result for the nonlinear degenerate parabolic system based on new energy estimate on pressures.     

Liquid-phase-based separation systems for depletion, prefractionation and enrichment of proteins in biological fluids and matrices for in-depth proteomics analysis--an update covering the period 2008-2011

This review article expands on the previous one (Jmeian, Y. and El Rassi, Z. Electrophoresis 2009, 30, 249-261) by reviewing pertinent literature in the period extending from early 2008 to the present. Similar to the previous review article, the present one is concerned with proteomic sample preparation (e.g. depletion of high-abundance proteins, reduction of the protein dynamic concentration range, enrichment of a particular subproteome), and the subsequent chromatographic and/or electrophoretic prefractionation prior to peptide separation and identification by LC-MS/MS. This review article differs from the first version published in Electrophoresis 2009, 30, 249-261 by expanding on capturing/enriching subglycoproteomics by lectin affinity chromatography. Ninety-eight articles published in the period extending from early 2008 to the present have been reviewed. By no means is this review article exhaustive: its aim is to give a concise report on the latest developments in the field.     

Naphthyl methacrylate‐based monolithic column for RP‐CEC via hydrophobic and π interactions

A neutral naphthyl methacrylate‐based monolith (NMM) was introduced for RP‐CEC of various aromatic compounds via hydrophobic and π interactions. It was characterized over a wide range of elution conditions to gain insight into its RP retention mechanism toward the various solute probes under investigation. First, the NMM column exhibited cathodal EOF at various mobile phase compositions and pH suggesting that although the NMM column is void of fixed charges, it acquires a negative zeta potential. It is believed that the negative zeta potential is imparted by the adsorption of mobile phase ions to the NMM surface. The NMM column exhibited π–π interactions in addition to hydrophobic interactions due to the aromatic and nonpolar nature of its naphthyl ligands. In all cases, the retention of the various aromatic test solutes including PAHs, benzene derivatives, toluene derivatives, anilines and toluidine, tolunitrile and nitrotoluene positional isomers on the NMM column were compared to their retention on an octadecyl acrylate‐based monolithic column. Not only were the values of the retention factors of the various solutes on the NMM column higher than those obtained on the octadecyl acrylate‐based monolithic column under otherwise the same CEC conditions, but the elution orders were also different on both columns with a superior and unique selectivity exhibited by the NMM column.     

The Potential Role of Nigella sativa Seed Oil as Epigenetic Therapy of Cancer

Nigella sativa oil, commonly known as black seed oil (BSO), is a well-known Mediterranean food, and its consumption is associated with beneficial effects on human health. A large number of BSO’s therapeutic properties is attributed to its pharmacologically active compound, thymoquinone (TQ), which inhibits cell proliferation and induces apoptosis by targeting several epigenetic players, including the ubiquitin-like, containing plant homeodomain (PHD) and an interesting new gene, RING finger domains 1 (UHRF1), and its partners, DNA methyltransferase 1 (DNMT1) and histone deacetylase 1 (HDAC1). This study was designed to compare the effects of locally sourced BSO with those of pure TQ on the expression of the epigenetic complex UHRF1/DNMT1/HDAC1 and the related events in several cancer cells. The gas chromatographs obtained from GC-MS analyses of extracted BSO showed that TQ was the major volatile compound. BSO significantly inhibited the proliferation of MCF-7, HeLa and Jurkat cells in a dose-dependent manner, and it induced apoptosis in these cell lines. BSO-induced inhibitory effects were associated with a significant decrease in mRNA expression of UHRF1, DNMT1 and HDAC1. Molecular docking and MD simulation showed that TQ had good binding affinity to UHRF1 and HDAC1. Of note, TQ formed a stable metal coordinate bond with zinc tom, found in the active site of the HDAC1 protein. These findings suggest that the use of TQ-rich BSO represents a promising strategy for epigenetic therapy for both solid and blood tumors through direct targeting of the trimeric epigenetic complex UHRF1/DNMT1/ HDAC1.     

Extraction of the Anticancer and Antimicrobial Agent,Prodigiosin, from Vibrio gazogenes PB1 and Its Identification by 1D and 2D NMR

Prodigiosin is a secondary metabolite produced in several species of bacteria. It exhibits antimicrobial and anticancer properties. Methods for the extraction and identification of prodigiosin and their related derivatives from bacterial cultures typically depend on solvent-based extractions followed by NMR spectroscopy. The estuarine bacterium, V. gazogenes PB1, was previously shown to produce prodigiosin. This conclusion, however, was based on analytical data obtained from ultraviolet-visible absorption spectrophotometry and infrared spectroscopy. Complete dependence on these techniques would be considered inadequate for the accurate identification of the various members of the prodiginine family of compounds, which possess very similar chemical structures and near-identical optical properties. In this study, we extracted prodigiosin from a culture of Vibrio gazogenes PB1 cultivated in minimal media, and for the first time, confirmed the synthesis of prodigiosin Vibrio gazogenes PB1 using NMR techniques. The chemical structure was validated by ¹H and ¹³C NMR spectroscopy, and further corroborated by 2D NMR, which included ¹H-¹H-gDQFCOSY, ¹H-¹³C-gHSQC, and ¹H-¹³C-gHMBC, as well as ¹H-¹H-homonuclear decoupling experiments. Based on this data, previous NMR spectral assignments of prodigiosin are reaffirmed and in some cases, corrected. The findings will be particularly relevant for experimental work relating to the use of V. gazogenes PB1 as a host for the synthesis of prodigiosin.     

Design,Synthesis and In-Vitro Biological Evaluation of Antofine and Tylophorine Prodrugs as Hypoxia-Targeted Anticancer Agents

Phenanthroindolizidines, such as antofine and tylophorine, are a family of natural alkaloids isolated from different species of Asclepiadaceas. They are characterized by interesting biological activities, such as pronounced cytotoxicity against different human cancerous cell lines, including multidrug-resistant examples. Nonetheless, these derivatives are associated with severe neurotoxicity and loss of in vivo activity due to the highly lipophilic nature of the alkaloids. Here, we describe the development of highly polar prodrugs of antofine and tylophorine as hypoxia-targeted prodrugs. The developed quaternary ammonium salts of phenanthroindolizidines showed high chemical and metabolic stability and are predicted to have no penetration through the blood–brain barrier. The designed prodrugs displayed decreased cytotoxicity when tested under normoxic conditions. However, their cytotoxic activity considerably increased when tested under hypoxic conditions.