Synthesis and tautomeric structure of 2-[N-aryl-2-oxo-2-arylethanehydrazonoyl]-6-methyl-4(3H)-pyrimidinones

Two series of 2-(N-aryl-2-oxo-2-arylethanehydrazonoyl)-6-methyl-4(3H)-pyrimidinones 11 (12) were prepared by coupling of diazotized anilines with 2-(aroylmethylene)-1,2-dihydro-6-methyl-4(3H)-pyrimidinones 2 (3). The spectral data of such compounds together with their 3-methyl analogs 13 (14) indicated that they exist predominantly in the hydrazone tautomeric form.     

Vapor-liquid and vapor-solid phase equilibria for united-atom benzene models near their triple points: the importance of quadrupolar interactions

Gibbs ensemble Monte Carlo simulations were used to calculate the vapor-liquid and vapor-solid coexistence curves for benzene using two simple united-atom models. An extension of the Gibbs ensemble method that makes use of an elongated box containing a slab of the condensed phase with a vapor phase along one axis was employed for the simulations of the vapor-solid equilibria and the vapor-liquid equilibria at very low reduced temperatures. Configurational-bias and aggregation-volume-bias Monte Carlo techniques were applied to improve the sampling of particle transfers between the two simulation boxes and between the vapor and condensed-phase regions of the elongated box. An isotropic united-atom representation with six Lennard-Jones sites at the positions of the carbon atoms was used for both force fields, but one model contained three additional out-of-plane partial charge sites to explicitly represent benzene's quadrupolar interactions. Both models were fitted to reproduce the critical temperature and density of benzene and yield a fair representation of the vapor-liquid coexistence curve. In contrast, differences between the models are very large for the vapor-solid coexistence curve. In particular, the lack of explicit quadrupolar interactions for the 6-site model greatly reduces the energetic differences between liquid and solid phases, and this model yields a triple point temperature that is about a factor of 2 too low. In contrast, the 9-site model predicts a triple point of benzene at T = 253 +/- 6 K and p = 2.3 +/- 0.8 kPa in satisfactory agreement with the experimental data (T = 278.7 K and p = 4.785 kPa).     

A new route for the functionalisation of wood through transesterification reactions

A novel transesterification reaction between acetylated maritime pine sapwood (Pinus pinaster Soland) and methyl benzoate (MB), in the presence of dibutyltin oxide (DBTO) as a catalyst, was performed. Reaction was confirmed by Fourier-transform infrared spectroscopy (FTIR) and ¹³C nuclear magnetic resonance cross-polarisation with magic-angle spinning (NMR CP MAS) analysis: signals corresponding to benzoylated wood were identified and, when transesterification was performed with ethyl trimethylsilylacetate (ETMSA), characteristic trimethylsilyl groups were detected. The acetyl/benzoyl exchange rate was found to increase with increasing amount of DBTO, temperature and reaction time and a concurrent deterioration of the woody material was evidenced.     

Distorted five-fold coordination of Cu2+(aq) from a Car-Parrinello molecular dynamics simulation

The solvation shell structure and dynamics of a single Cu2+ ion in a periodic box with 32 water molecules under ambient conditions has been investigated using Car-Parrinello molecular dynamics simulations in a time-window of 18 ps. Five-fold coordination with four equidistant equatorial water molecules at 2.00 A and one axial water molecule at 2.45 A from the Cu2+ ion is found. A "hole" without water molecules is found on the opposite side of the axial water. The ion-water bonding character for the equatorial water molecules is different from that of the axial water molecules, as shown by a localized orbital analysis of the electronic structure. Moreover, the calculated OD stretching vibrational band for the equatorial water molecules lies ca. 175 cm-1 below the axial-water band, in good agreement with experimental data. The equatorial-water band lies below, and the axial-water band above, the pure liquid D2O band, also in agreement with experimental data.     

Microscale Thermophoresis and Molecular Modelling to Explore the Chelating Drug Transportation in the Milk to Infant

The microscale thermophoresis (MST) technique was utilized to investigate lactoferrin–drug interaction with the iron chelator, deferiprone, using label-free system. MST depends on the intrinsic fluorescence of one interacting partner. The results indicated a significant interaction between lactoferrin and deferiprone. The estimated binding constant for the lactoferrin–deferiprone interaction was 8.9 × 10⁻⁶ ± 1.6, SD, which is to be reported for the first time. Such significant binding between lactoferrin and deferiprone may indicate the potentiation of the drug secretion into a lactating mother’s milk. The technique showed a fast and simple approach to study protein–drug interaction while avoiding complicated labeling procedures. Moreover, the binding behavior of deferiprone within the binding sites of lactoferrin was investigated through molecular docking which reflected that deferiprone mediates strong hydrogen bonding with ARG121 and ASP297 in pocket 1 and forms H-bond and ionic interaction with ASN640 and ASP395, respectively, in pocket 2 of lactoferrin. Meanwhile, iron ions provide ionic interaction with deferiprone in both of the pockets. The molecular dynamic simulation further confirmed that the binding of deferiprone with lactoferrin brings conformational changes in lactoferrin that is more energetically stable. It also confirmed that deferiprone causes positive correlation motion in the interacting residues of both pockets, with strong negative correlation motion in the loop regions, and thus changes the dynamics of lactoferrin. The MM-GBSA based binding free energy calculation revealed that deferiprone exhibits ∆G TOTAL of −63,163 kcal/mol in pocket 1 and −63,073 kcal/mol in pocket 2 with complex receptor–ligand difference in pocket 1 and pocket 2 of −117.38 kcal/mol and −111.54 kcal/mol, respectively, which in turn suggests that deferiprone binds more strongly in the pocket 1. The free energy landscape of the lactoferrin–deferiprone complex also showed that this complex remains in a high energy state that confirms the strong binding of deferiprone with the lactoferrin. The current research concluded that iron-chelating drugs (deferiprone) can be transported from the mother to the infant in the milk because of the strong attachment with the lactoferrin active pockets.     

Chemical Profiles and Pharmacological Properties with in Silico Studies on Elatostema papillosum Wedd

The current study attempted, for the first time, to qualitatively and quantitatively determine the phytochemical components of Elatostema papillosum methanol extract and their biological activities. The present study represents an effort to correlate our previously reported biological activities with a computational study, including molecular docking, and ADME/T (absorption, distribution, metabolism, and excretion/toxicity) analyses, to identify the phytochemicals that are potentially responsible for the antioxidant, antidepressant, anxiolytic, analgesic, and anti-inflammatory activities of this plant. In the gas chromatography-mass spectroscopy analysis, a total of 24 compounds were identified, seven of which were documented as being bioactive based on their binding affinities. These seven were subjected to molecular docking studies that were correlated with the pharmacological outcomes. Additionally, the ADME/T properties of these compounds were evaluated to determine their drug-like properties and toxicity levels. The seven selected, isolated compounds displayed favorable binding affinities to potassium channels, human serotonin receptor, cyclooxygenase-1 (COX-1), COX-2, nuclear factor (NF)-κB, and human peroxiredoxin 5 receptor proteins. Phytol acetate, and terpene compounds identified in E. papillosum displayed strong predictive binding affinities towards the human serotonin receptor. Furthermore, 3-trifluoroacetoxypentadecane showed a significant binding affinity for the KcsA potassium channel. Eicosanal showed the highest predicted binding affinity towards the human peroxiredoxin 5 receptor. All of these findings support the observed in vivo antidepressant and anxiolytic effects and the in vitro antioxidant effects observed for this extract. The identified compounds from E. papillosum showed the lowest binding affinities towards COX-1, COX-2, and NF-κB receptors, which indicated the inconsequential impacts of this extract against the activities of these three proteins. Overall, E. papillosum appears to be bioactive and could represent a potential source for the development of alternative medicines; however, further analytical experiments remain necessary.     

Cellulosic nanoparticles from alfa fibers (<Emphasis Type="Italic">Stipa tenacissima)</Emphasis>: extraction procedures and reinforcement potential in polymer nanocomposites

The microstructure and chemical composition of alfa (Stipa tenacissima) were investigated. The polysaccharide and lignin contents were around 70 and 20 wt%, respectively. From the bleached and delignified fibers, two types of nanosized cellulosic particles were extracted, namely cellulose nanocrystals and microfibrillated cellulose (MFC). The former correspond typically to the elementary crystallite units of the cellulose fibers, with a rod-like morphology and an aspect ratio of about 20. The latter, mechanically disintegrated from oxidized bleached fibres, presents an entangled fibrillar structure with widths in the range 5-20 nm. The reinforcing potential of the ensuing nanoparticles was investigated by casting a mixture of acrylic latex and aqueous dispersion of cellulose nanoparticles. Thermo-mechanical analysis revealed a huge enhancement of the stiffness above the glass transition of the matrix. Significant differences in the mechanical reinforcing capability of the nanoparticles were reported.     

Dirac equation with multiparameter-potential and Hulthén tensor interaction under relativistic symmetries

The pseudospin and spin symmetric solutions of the Dirac equation with Hulthén-type tensor interaction are obtained under multi-parameter-exponential potential (MEP) for arbitrary κ states. The energy eigenvalues and the corresponding eigenfunctions are also obtained using the parametric Nikiforov-Uvarov (NU) method. Some numerical results are also obtained for pseudospin and spin symmetry limits.