Thermodynamic characterization of the dimerization equilibrium of newly synthesized polymethine cyanine dyes

The monomer–dimer equilibrium and thermodynamics of three new cyanine dyes were investigated by spectrophotometric and chemometric methods. The dimerization constants of these new cyanine dyes were determined by studying the dependence of their absorption spectra on the temperature in the range 25–80 °C at concentrations of 3.0×10-4, 1.9×10-4 and 1.1×10-4 M for dye 1, 2 and 3, respectively. The processing of the data, performed for the quantitative analysis of pure spectral profiles, was based on the simultaneous resolution of the overlapping bands in the whole set of absorption spectra. From the dimerization constant and its dependence on temperature, the values of the standard enthalpy change and entropy change of dimerization were calculated

Voltammetric electronic tongue for the simultaneous determination of three benzodiazepines

The presented manuscript reports the simultaneous detection of a ternary mixture of the benzodiazepines diazepam, lorazepam, and flunitrazepam using an array of voltammetric sensors and the electronic tongue principle. The electrodes used in the array were selected from a set of differently modified graphite epoxy composite electrodes; specifically, six electrodes were used incorporating metallic nanoparticles of Cu and Pt, oxide nanoparticles of CuO and WO, plus pristine electrodes of epoxy-graphite and metallic Pt disk. Cyclic voltammetry was the technique used to obtain the voltammetric responses. Multivariate examination using Principal Component Analysis (PCA) justified the choice of sensors in order to get the proper discrimination of the benzodiazepines. Next, a quantitative model to predict the concentrations of mixtures of the three benzodiazepines was built employing the set of voltammograms, and was first processed with the Discrete Wavelet Transform, which fed an artificial neural network response model. The developed model successfully predicted the concentration of the three compounds with a normalized root mean square error (NRMSE) of 0.034 and 0.106 for the training and test subsets, respectively, and coefficient of correlation R ≥ 0.938 in the predicted vs. expected concentrations comparison graph

3D-QSAR and Docking Studies of a Series of β-Carboline Derivatives as Antitumor Agents of PLK1

An alignment-free, three dimensional quantitative structure-activity relationship (3D-QSAR) analysis has been performed on a series of β-carboline derivatives as potent antitumor agents toward HepG2 human tumor cell lines. A highly descriptive and predictive 3D-QSAR model was obtained through the calculation of alignment-independent descriptors (GRIND descriptors) using ALMOND software. For a training set of 30 compounds, PLS analyses result in a three-component model which displays a squared correlation coefficient (r2) of 0.957 and a standard deviation of the error of calculation (SDEC) of 0.116. Validation of this model was performed using leave-one-out, q2loo of 0.85, and leave-multiple-out. This model gives a remarkably high r2pred(0.66) for a test set of 10 compounds. Docking studies were performed to investigate the mode of interaction between β-carboline derivatives and the active site of the most probable anticancer receptor, polo-like kinase protein

Comparison of three sensory characterization methods based on consumer perception for the development of a novel functional cereal-based dessert

Milk can be modified by several processes to yield numerous kinds of food products with specific functional properties besides increasing the food value. This study aimed to evaluate the effect of various concentration of cereal flours (10–16%), inulin (6 and 8%) and sugar (2 and 4%) on sensory characteristic, consumer acceptance and drivers of liking of a new low sugar/fat prebiotic dairy dessert. In this way, descriptive analysis with trained panelists and three consumer profiling techniques were used and the agreement between them was compared. Nine samples of desserts with different concentration of flour, inulin and sugar were formulated using a mixture design. The samples were evaluated by a panel of 120 consumers, randomly divided into three groups of 40, who evaluated sensory characteristics of the desserts using intensity scale, or a check-all-that-apply (CATA questions) or open-ended questions. Results revealed that various concentration of cereal flours, inulin and sugar resulted in significant changes in the sensory properties of the desserts. Adding higher levels of inulin and sugar led to lower intensities in attributes thickness and creaminess. Samples with higher level of flour and lower level of inulin and sugar were liked by consumers and their high intensities in creaminess and thickness drove liking. Results showed that all the three consumer profiling techniques yielded similar information to descriptive analysis with the trained panel. Likewise, sample configurations from the CATA questions were the most similar to those afforded by the panel of trained assessors. These methodologies could be appealing techniques to investigate the relationship between sensory data and consumer description. Moreover, sensory techniques using consumer perception showed to be valuable to develop functional dessert, which is very important in market succession

Dynamic structure based pharmacophore modeling of the Acetylcholinesterase reveals several potential inhibitors

<p>Acetylcholinesterase is a critical enzyme that regulates neurotransmission by catalyzing the breakdown of neurotransmitter acetylcholine in synapses of the nervous system. It is an important target for therapeutic drugs that treat Alzheimer’s disease. Since, the degree of flexibility of the side chains of the residues in the active-site gorge of Acetylcholinesterase is diverse it results in different bound ligand conformations. The side-chain conformations of Ser293, Tyr341, Leu76, and Val73 are flexible, while the side-chain conformations of Tyr72, Tyr 124, Ser125, Phe295, and Arg296 appear to be fixed. In this study, multi-conformation dynamic pharmacophore models from the donepezyl-binding pocket based on highly populated structures chosen from molecular dynamics simulations were used for screening compounds that can properly bind acetylcholinesterase. Based on these structures, three pharmacophore models were generated. Consequently, 14 hits were retrieved as final candidates by utilizing virtual screening of ZINC database and molecular docking.</p

Coumarin derivative-functionalized nanoporous silica as an on–off fluorescent sensor for detecting Fe3+ and Hg2+ ions: a circuit logic gate

Abstract A highly efficient fluorescent sensor (S-DAC) was easily created by functionalizing the SBA-15 surface with N-(2-Aminoethyl)-3-Aminopropyltrimethoxysilane followed by the covalent attachment of 7-diethylamino 3-acetyl coumarin (DAC). This chemosensor (S-DAC) demonstrates selective and sensitive recognition of Fe3+ and Hg2+ in water-based solutions, with detection limits of 0.28 × 10–9 M and 0.2 × 10–9 M for Hg2+ and Fe3+, respectively. The sensor’s fluorescence characteristics were examined in the presence of various metal ions, revealing a decrease in fluorescence intensity upon adding Fe3+ or Hg2+ ions at an emission wavelength of 400 nm. This sensor was also able to detect ferric and mercury ions in spinach and tuna fish. The quenching mechanism of S-DAC was investigated using UV–vis spectroscopy, which confirmed a static-type mechanism for fluorescence quenching. Moreovre, the decrease in fluorescence intensity caused by mercury and ferric ions can be reversed using trisodium citrate dihydrate and EDTA as masking agents, respectively. As a result, a circuit logic gate was designed using Hg2+, Fe3+, trisodium citrate dihydrate, and EDTA as inputs and the quenched fluorescence emission as the output. Graphic abstrac