Molecular docking studies of coumarin hybrids as potential acetylcholinesterase,butyrylcholinesterase, monoamine oxidase A/B and β-amyloid inhibitors for Alzheimer’s disease

Coumarins are the phytochemicals, which belong to the family of benzopyrone, that display interesting pharmacological properties. Several natural, synthetic and semisynthetic coumarin derivatives have been discovered in decades for their applicability as lead structures as drugs. Coumarin based conjugates have been described as potential AChE, BuChE, MAO and β-amyloid inhibitors. Therefore, the objective of this review is to focus on the construction of these pharmacologically important coumarin analogues with anti-Alzheimer’s activities, highlight their docking studies and structure–activity relationships based on their substitution pattern with respect to the selected positions on the chromen ring by emphasising on the research reports conducted in between year 1968 to 2017.

Open image in new window

     

Investigating green ethers for the precipitation of peptides after global deprotection in solid-phase peptide synthesis

1. Download : Download high-res image (250KB)
2. Download : Download full-size image

     

Bioeconomic modeling of household waste recovery

The ecological consciousness has driven developed societies to explore alternatives to the growing need for energy and the consequent increase in waste production. The adjustment towards the waste recovery and their transformation into energy, by various processes, is then necessary. However, so far, the domain has not benefited much from a mathematical modeling approach. The main contribution of this work consists of building a bioeconomic model describing the problem of a potential investor who aims to maximize his net profit generated by selling the produced energy from the household waste transformation. We first study the evolution of a waste stock, the energy quantity produced, and the capital dedicated to the transformation process in a giving landfill and recovery center. Then we insert decision variables to this dynamic which are both the investment and the part of waste to be treated. This leads to an optimal control problem which we solve by the deductive method. The resulted solution is then illustrated by some numerical simulations. This investment policy would be to support the decision makers to go towards investment in this activity.     

Quality by Design-Guided Development of a Capillary Electrophoresis Method for the Chiral Purity Determination of Ambrisentan

A quality by design approach utilizing experimental design methodologies was applied to develop a CE method to evaluate the enantiomeric purity of (S)-ambrisentan, a selective endothelin receptor antagonist used for the treatment of pulmonary arterial hypertension. Initial method scouting was performed by screening native cyclodextrins (CDs) as well as neutral CD derivatives and a positively charged derivative at pH 5 and pH 9, identifying γ-CD as suitable selector at pH 5. Upon defining the critical quality attributes and the critical process parameters, i.e., chiral resolution and run time, method development was performed by application of a screening design for the identification of the significant variables and, subsequently, by a response surface methodology for obtaining the design space. A Plackett–Burman design was employed for robustness testing. The final working point conditions used a background electrolyte composed of a 50-mM sodium acetate buffer, pH 4.0, containing 30 mM γ-CD in a 75-μm ID fused-silica capillary with an effective length of 40 cm at an applied voltage of 25 kV and a capillary temperature of 25 °C. The method was validated according to the ICH Q2(R1) guideline and allowed the determination of a relative concentration of the (R)-enantiomer of 0.1 %.

     

Universally catenarian and going-down pairs of rings

For a ring extension is called a universally catenarian pair if every domain , is universally catenarian. When R is a field it is shown that the only universally catenarian pairs are those satisfying . For several satisfactory results are given. The second purpose of this paper is to study going-down pairs (Definition 5.1). We characterize these pairs of rings and we establish a relationship between universally catenarian, going-down and residually algebraic pairs. Received: 1 July 1999; in final form: 5 June 2000 / Published online: 17 May 2001     

Sol–gel synthesis of NiFe2O4 with PVA matrices and their catalytic activities for one-step hydroxylation of benzene into phenol

Nickel ferrite (NiFe₂O₄) was synthesized using citric acid (CA) as a chelating agent and varying amounts of polyvinyl alcohol (PVA) as powder binder via a combustion process. The influence of PVA/NiFe₂O₄ blend composition on the phase, crystal structure, and morphology has been investigated by X-ray diffraction (XRD), scanning electron microscopy, and Fourier transform infrared spectroscopy, respectively. The probable assignments of the thermal degradation products of PVA/NiFe₂O₄ were studied by complementary thermogravimetric analysis and differential thermal analysis. The PVA/NiFe₂O₄ crystals preferentially oriented along the (311) plane as revealed by XRD, owing to diffusion of α-Fe₂O₃ particles into the lattice matrix where the rate of diffusion increased significantly with the PVA concentration increase from 0.1 to 0.3 mol%. A vibrational doublet at 1,644 and 1,609 cm^?1 for the ≡Fe–O–COOH complex was emitted in the spectra of PVA-impregnated NiFe₂O₄ to assure the attachment of Fe(III) to the chelating agents CA/PVA. Thermal kinetic consideration based on Coats–Redfern and Horowitz–Metzger equations at subsequent decomposition steps of CA/PVA/NiFe₂O₄ illustrated that the values of activation free energy ΔG* increase significantly, indicating the non-spontaneous behavior. The one-step direct hydroxylation of benzene toward phenol has been extensively investigated using hydrogen peroxide as an oxidant.     

Fuzziness in abacus logic

The concept of abacus logic has recently been developed by the author (Malhas, n.d.). In this paper the relation of abacus logic to the concept of fuzziness is explored. It is shown that if a certain regularity condition is met, concepts from fuzzy set theory arise naturally within abacus logics. In particular it is shown that every abacus logic then has a pre-Zadeh orthocomplementation. It is also shown that it is then possible to associate a fuzzy set with every proposition of abacus logic and that the collection of all such sets satisfies natural conditions expected in systems of fuzzy logic. Finally, the relevance to quantum mechanics is discussed.     

Characterization and microstructural studies of LiFe5O8 synthesized by the self propagating high temperature combustion method

LiFe₅O₈ was synthesized by the self-propagating high temperature combustion synthesis using lithium acetate and iron acetate as starting materials and glycine as reductant. The reaction was rapid when the ignition temperature was reached and the product was a light and porous mass of solid material. Analysis using X-Ray powder diffraction and SEM revealed the amorphous nature of the LiFe₅O₈ precursor material. From particle size analysis, the precursor material was much less than 100 nm, but increased upon annealing at 650 °C and 900 °C. Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 – 8, 2005.     

Preparation,spectral and thermal properties of new Isoflavone derivatives: mesomorphic properties and DFT studies

The four new homologous series of symmetric Isoflavon dimers were synthesised using varied alkyl/aryl diamines in linear sense. The chemical structures of the molecules were characterised by IR, NMR and CHNS analysis. Further, Liquid crystalline properties were verified using the combination of differential scanning calorimetry (DSC) and polarised optical microscope (POM). The molecular systems studied here reveal that LC property depends on the length of the middle connecting diamine spacer along with terminal alkyl spacer. The lower members favour to exhibit smectic A phase, whereas higher members exhibit nematic mesophase. The nature of LC property behaviours is supported by molecular geometries studied by DFT calculations.