Interaction and solubilization of some phenolic antioxidants in Pluronic® micelles

The solubilization of four phenolic antioxidants, namely p-hydroxybenzoic acid (PHBAA), syringic acid, sinapic acid, and quercetin in micelles of an ethylene oxide (EO)–propylene oxide (PO) triblock copolymer Pluronic^® P104 (EO₂₇–PO₆₁–EO₂₇, PPO mol wt = 3540, % PEO = 40) was examined at different temperatures, pHs, and in the presence of sodium chloride. The nano-size core–shell micelles of P104 characterized by dynamic light scattering had hydrodynamic diameter of about 18–20 nm with low polydispersity. Antioxidants induced micellization and micellar growth were observed. The critical micellar concentration (CMC), critical micellar temperature (CMT), cloud point (CP) of P104 decreased due to solubilization and interactions of antioxidants. The solubilization was favored at higher temperature, pH and in the presence of salt and follows the order PHBA > syringic acid > sinapic acid > quercetin which corresponds to the trend in their aqueous solubility. The location of antioxidant in micelles observed from NOESY spectra. Structure and hydrophobicity of antioxidants were found to be governing factors for their interaction and location in the micelles.     

Cadmium(II) N-acetylcysteine complex formation in aqueous solution

The complex formation between Cd(II) ions and N-acetylcysteine (H(2)NAC) in aqueous solution was investigated using Cd K- and L(3)-edge X-ray absorption and (113)Cd NMR spectroscopic techniques. Two series of 0.1 M Cd(II) solutions with the total N-acetylcysteine concentration c(H2NAC) varied between 0.2-2 M were studied at pH 7.5 and 11.0, respectively. At pH = 11 a novel mononuclear [Cd(NAC)(4)](6-) complex with the average Cd-S distance 2.53(2) ? and the chemical shift δ((113)Cd) = 677 ppm was found to dominate at a concentration of the free deprotonated ligand [NAC(2-)] > 0.1 M, consistent with our previous reports on cadmium tetrathiolate complex formation with cysteine and glutathione. At pH 7.5 much higher ligand excess ([HNAC(-)] > 0.6 M) is required to make this tetrathiolate complex the major species. The (113)Cd NMR spectrum of a solution containing c(Cd(II)) = 0.5 M and c(H2NAC) = 1.0 M measured at 288 K showed three broad signals at 421, 583 and 642 ppm, which can be attributed to CdS(3)O(3), CdS(3)O and CdS(4) coordination sites, respectively, in oligomeric Cd(II)-NAC species with single thiolate bridges between the cadmium ions.     

N-heterocyclic carbene catalyzed aroylation of 3,5-dichloro-2(1H)-pyrazinones

The N-heterocyclic carbene catalyzed chemoselective C3-aroylation of 3,5-dichloro-2(1H)-pyrazinones with various aldehydes is reported. We herein describe results of this remarkable mild and efficient procedure.     

Effect of substituent of terpyridines on the DNA-interaction of polypyridyl ruthenium(II) complexes

An octahedral complexes of ruthenium with 2,9-dimethyl-1,10-phenanthroline (dmphen) and substituted terpyridine have been synthesized. The Ru(II) complexes have been characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, FT-IR, electronic, (1)H NMR and FAB mass spectra. The binding strength and mode of interaction of the complexes with Herring Sperm DNA has been investigated using absorption titration and viscosity measurement studies. Results suggest that the substituent on terpyridine ligand affects the binding mode and binding ability of the complexes. Effect of time and ionic strength on DNA cleavage ability of complex has also been studied by gel electrophoresis. Results suggest that more than 200 mM concentration of NaCl decreases the cleavage ability of complex.     

Fourier Transform 13C NMR Analysis of Some Methaqualone Metabolites

The natural abundance carbon-13 nuclear magnetic resonance spectra of some methaqualone metabolites were recorded using the pulse fourier transform technique. The chemical shift of various carbon resonances have been assigned on the basis of the chemical shift theory, multiplicities observed in SFORD spectrum and comparison with the chemical shifts of the corresponding carbons of methaqualone.     

Effect of pressure on optical and electrical properties of tungsten diselenide single crystals

Optical absorption spectra of tungsten diselenide (WSe₂) single crystals subjected to different values of pressure (0, 2, 4 and 6 GPa) were obtained in the spectral range 700–1450 nm with the help of a UV–VIS–NIR spectrophotometer. The spectra were thoroughly analyzed in the absorption edge region for obtaining direct as well as indirect band gaps in this material. The high temperature resistivity and thermoelectric power on WSe₂ single crystals at various pressures were also studied. The results and their implications are discussed in the article.     

Transport studies of water and aqueous—dioxane through a pyrex sintered disc impregnated with cellulose acetate

Experimental results for the measurements of hydrodynamic permeability, electroosmotic velocity and streaming potential of water and dioxane—water (DH₂O) mixtures (10, 20, 30 and 40% by mass of dioxane) using a pyrex sintered disc (G₂) impregnated with cellulose acetate at 30°C and at voltages up to 40 V are reported. The data have been analysed in the light of non-equilibrium thermodynamics. Onsager's reciprocity relation for all compositions of aqueous—dioxane has been found to hold true. It has been found that the concentration dependence of the phenomenological coefficients conform to the Spiegler's frictional model. Efficiencies of electrokinetic energy conversion, i.e. electroosmosis and streaming potential, have been determined and the results are in accordance with the theory of non-equilibrium thermodynamics. The maximum value of the efficiency of energy conversion for both the modes has been found to be independent of the input force. Membrane characteristics such as pore radius and number of pores have been determined, whereas the membrane—permeant interface is characterised in term of the zeta potential.     

Meticulous assessment of natural compounds from NPASS database for identifying analogue of GRL0617, the only known inhibitor for SARS-CoV2 papain-like protease (PLpro) using rigorous computational workflow

Molecular Diversity - The latest global outbreak of 2019 respiratory coronavirus disease (COVID-19) is triggered by the inception of novel coronavirus SARS-CoV2. If recent events are of any...