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  • Open access
  • 31 Reads
In vitro and in silico investigations on natural compounds with predicted activity against neuroblastomas

In the present study, the ability of an ethanolic extract from Stokesia laevis to inhibit the development of human glioblastoma cell line U87 has been investigated; cytotoxic activity has been estimated at 78%, by comparison with the control cells, glial cell line NHA, while IC50 values were 9.12 μg gallic acid equivalents per 1 mL extract for U87, and 24.17 μg gallic acid equivalents per 1 mL extract for NHA, respectively. Docking simulation using the active compounds in stokesia aster, by comparison with curcumin, on the Bcl-2 anti-apoptotic protein target have revealed the following order in magnitude of the docking score: native ligand > curcumin > luteolin-7-O-glucoside > luteolin-8-O-glucoside > luteolin, with RMSD between 0.01 and 0.93. Since the access to neuroblastomas is no longer restricted by the blood-brain barrier, in the same time a selective cytotoxicity has been demonstrated, higher on tumor astrocytes than the normal astrocytes, it was concluded the potential use of stokesia aster ethanolic extracts and luteolin derivates as an alternative in neuroblastomas approach.

  • Open access
  • 26 Reads
Electrochemical transformation of bio-derived furans using a salen-manganese homogeneous catalyst

A sustainable model society requires a change from an economy based in fossil resources to the so-called bio-based economy, where most of the chemicals and materials are produced from renewable feedstocks like biomass. The development of new catalysts for the transformation of biomass derived compounds into valued-added chemicals and liquid fuels is highly desirable to overcome the key challenges for market penetration of the sustainable biomass-based products. 5-hydroxymethylfurfural (HMF) is one of these most promising products, which has the potential to be converted to a variety of useful intermediates for polymers and many other fine chemicals.

In this communication, we report the electrochemical oxidation of HMF to DMF (2,5-furandicarboxaldehyde) catalysed by a salen-manganese homogeneous catalyst. DMF is a versatile precursor in the synthesis of functional polymers, pharmaceuticals, antifungal agents, and furan-urea resins. A manganese(III)-Schiff base complex 1 was synthetized and characterized by different analytical and spectroscopic techniques. Complex 1 behaves as a peroxidase mimic and also as an efficient catalyst for electrochemical oxidation of HMF to DMF. Conversion of HMF to DFF was performed under mild conditions in saline media, following a procedure developed by us. Oxidation of DFF to HMF with conversion rate of 75% was achieved at pH 8.5, phosphate buffer and using sodium chloride as electrolyte to increase the conductivity and to reduce power dissipation. The role of the catalyst is this process is also discussed in this communication.

  • Open access
  • 117 Reads
Computational Survey of Two Specific Chalcone Derivatives to Study Their Structural, Electronic, Physical, and Chemical Behaviour
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Two previously reported 2,3-dihydro-1H-inden-1-one derived chalcone derivatives have been studied using density functional theory (DFT) calculation. This computational approach includes structural, electronic, physical, and chemical behaviour of (E)-2-(thiophen-2-ylmethylene)-2,3-dihydro-1H-inden-1-one (TMDHI) and (E)-2-((1H-pyrrol-2-yl)methylene)-2,3-dihydro-1H-inden-1-one (PMDHI). The geometry of compounds was optimized by employing the DFT method with the B3LYP/6-311G (d,p) basis set. In this comparative study, various properties such as bond angle, bond length, dipole moment, augmentation in dipole moment, and total energy of TMDHI and PMDHI are revealed. Also, the study shows that, the Mulliken atomic charges analysis revealed that all hydrogen atoms in both compounds have a positive charge and the molecular electrostatic surface potential plot of the tittle compounds showed negative potential is located around oxygen atoms.

  • Open access
  • 22 Reads
Modifications in Thermal and Anticorrosive Characteristics of Haemoglobin-doped Polyindole

A method of doping of Haemoglobin (Hb) into Polyindole (PIN) was developed to accomplish the haemoglobin polyindole composite (HPC) with improved electrochemical performance and maintained thermal stability. The scheme of doping was accomplished through cationic surfactant assisted dilute polymerization of indole (0.12 mol dl-1) in the presence of ferric chloride oxidant (1.85 X 10-2 mol dl-1) augmentation with indispensable weight of Hb (1%; w/w). The formation of HPC was ascertained through scanning electron microscopy (SEM), thermogravimetric-differential thermal analysis-differential thermogravimetry (TG-DTA-DTG) and electrochemical impedance spectra (EIS). Working electrode was derived from PIN and HPC in the presence of sulphonated polysulphone binder in graphite matrix. The specific capacitance (Cs Fg−1) of PIN and respective HPC (1%w/w) electrodes has been 21.60 and 39.40 respectively. In order to have further imminent into the consequence of Hb on the stability, the SEM images have been recorded before and after polarization experiments. The rendered enhanced impact, thermal stability and remarkable potential as anticorrosive coating.

  • Open access
  • 29 Reads
DFT studies on the allylation of styrene oxide catalysed by indium nanoparticles (InNPs)

Organometallic compounds provide a source of nucleophilic carbon centers which can react with electrophiles to form new carbon-carbon bonds. In particular, allyl-indium species are known to react with various electrophiles, such as carbonyl compounds, to generate homoallylic alcohols. Epoxides are good electrophiles that could react with organometallic compounds. The intrinsic tension of these cyclic systems makes them very reactive starting materials, giving access to more complex products through the regiochemical controlled ring-opening. With this aim, the allylation of epoxides with indium powder has been reported by several research groups.

In this work, indium nanoparticles (InNPs) has been prepared through a simple methodology, under mild reaction conditions, by fast reduction of indium(III) chloride with lithium sand and a catalytic amount of 4,4’-di-tert-butylbiphenyl (DTBB), in THF as solvent, at room temperature and under nitrogen atmosphere. The freshly prepared InNPs, were employed as catalysts for the ring-opening allylation reaction of styrene oxide with allyl or prenyl bromides, working both at room temperature and under reflux of ACN or THF. Moreover, the reactions were studied by the adding the reactants under both Grignard and Barbier conditions.

To provide a clearer understanding of the experimental results, computational analyses by using the Gaussian09 program were performed. DFT calculations were executed with the B3LYP functional, and LanL2DZ pseudopotential. All the possible reaction paths for the formation of the different alcohol products were calculated, achieving very good correlation between the experimental and computational results.

  • Open access
  • 31 Reads
Highly Efficient Approach to the Synthesis of New Chromeno[2,3-d] Pyrimidine derivatives

5H-chromeno[2,3-d]pyrimidines constitute an important class of heterocyclic compounds having diverse biological activities such as antifungal, anti-tumor, antibacterial, antihypertensive activities. In the continuation of our research aimed at developing new methods for the preparation of new heterocyclic compounds, we present in this work, a simple, efficient, and environmentally approach for the synthesis of new and functionalized chromeno[2,3-d]pyrimidines derivatives by the treatment of 2-amino-3-cyano-4H-chromenes with anhydride acetic under solvent-free conditions

  • Open access
  • 24 Reads
Rearrangement of imidazolidine to piperazine rings in the presence of DyIII

The formation of imidazolidines from secondary amines and aldehydes is well known. This small cycle can act as nitrogen donor, and it is usually stable when it coordinates to metal ions. Sometimes, the imidazolidines as ligands undergo breaking of the C-N bond when coordinating to the metal centre, yielding related amines. However, the reorganisation of the imidazolidine to a piperazine ring is a quite unusual process. In this work, we describe the transformation of a zinc complex with a ligand containing two imidazolidine moieties into a zinc complex with two piperazine fragments as donors, in the presence of a dysprosium salt.

  • Open access
  • 38 Reads
Preparation and Hydro-lipophilic properties of monosubstituted N-aryl-4-hydroxyquinoline-3-carboxanilides

A series of twenty-two monosubstituted N-aryl-4-hydroxyquinoline-3-carboxanilides designed as dual anti-invasive agents was prepared and characterized. Lipophilicity significantly affects biological activities of compounds and ADME properties, therefore the lipo-hydrophilic properties of these 4-hydroxyquinoline-3-carboxanilides were investigated. All the derivatives were analyzed by reversed-phase high-performance liquid chromatography. The procedure was carried out under isocratic conditions with methanol as the organic modifier in the mobile phase using an end-capped non-polar C18 stationary reversed-phase column. In this study, correlations between the logarithm of the capacity factor k and log P/Clog P values calculated by various methods are discussed, as well as the relationships between lipophilicity and chemical structure of the studied compounds.

  • Open access
  • 41 Reads
Synthesis of new thiophenic derivatives

In recent years, Thiophene and its derivatives have known an increasing importance as intermediates to biologically active compounds and in organic synthesis . 2-Amino-3-functionally substituted thiophene derivatives have been studied as probe molecules in chemical biology and drugs or hits in medicinal chemistry . They are also used as precursors in the azo dye and pharmaceutic industries . 2-aminothiophene is a central five-membered heterocyclic core that is prepared using Gewald methodology , which known several modifications to target a wide range of substrate. The use of inorganic bases like sodium bicarbonate, sodium hydroxide , sodium carbonate instead of morpholine, pyridine, triethylamine , Organic reactions in heterogeneous phase . All of them seemed advantageous over conventional systems. The presence of the two active sites CN and NH2 in 2-Amino-3-cyano substituted thiophene derivatives offers a multitude of interesting reactions such as the preparation of tetrazole derivatives very well-known by their exceptional properties; a large number of nitrogen atoms, good stability, acidity and basicity in addition to several properties in medicinal, biological and material sciences . Tetrazole derivatives are known for their molecular fluorescence. Our laboratory interested in the development and functionalization of heterocyclic compounds with promising biological and pharmacological activities including some new concept of green chemistry ; as a part of our research, different types of 2-aminothiophenes were achieved in good yields that are then used to prepare tertazole derivatives.

  • Open access
  • 91 Reads
Computational Revision of the Mechanism of the Thorpe Reaction

The Thorpe reaction is described as a self-condensation of nitriles in the presence of a basic catalyst producing an imine which tautomerizes spontaneously into a β-enaminonitrile. This reaction is studied because of its wide applications in the synthesis of cyclic, aromatic, and open-chain nitrogen derivatives. However, its reaction mechanism has not yet been studied with modern methods allowing the development of the experimental synthesis through a more economical, efficient and safety route. We performed theoretical calculations within the Density Functional Theory (DFT) framework at the ωB97XD/def2-svpd level to explore different mechanistic proposals when propionitrile is used as reagent and sodium ethoxide (EtONa) as catalyst. Furthermore, the influence of different solvents, such as ethanol (EtOH), tetrahydrofuran (THF), 1,2-dimethoxyethane (DME) and propionitrile (EtCN), was assessed. Finally, we also evaluated the effect of fluorine group (-F), compared to the methyl group (-CH3), substituted in the α position of acetonitrile (MeCN). Our theoretical findings show that THF and DME are the best solvents to perform the reaction. Also, a fluorine group, as an electron withdrawing group, in the α position decreases both the activation energy and the Gibbs free energy of the reaction. This is in agreement with different experimental reports on the Thorpe reaction.