Validated UPLC method for the determination of guaiphenesin,oxeladin citrate,diphenhydramine, and sodium benzoate in their quaternary mixture used in treatment of cough,in the presence of guaiphenesin-related substance (guaiacol)

Accurate, precise, and sensitive UPLC method was developed and validated for the simultaneous determination of a quaternary mixture containing guaiphenesin (GUP), oxeladin citrate (OXC), diphenhydramine (DPH), and sodium benzoate (SOB) in the presence of GUP-related substance, guaiacol (GUA). Chromatographic separation was achieved using NUCLEOSHELL^® column—C₁₈ (4.0?×?50.0 mm, 2.7 μm). Isocratic elution at a flow rate 1.0 mL/min was performed using a mobile phase consisting of acetonitrile:phosphate buffer pH 3.5?±?0.1 (25.0:75.0, v/v). The specificity of the developed method was investigated by analyzing of laboratory-prepared mixtures containing different ratios of the four drugs, in the presence of GUA as well as their combined pharmaceutical formulation. The obtained results were statistically compared with those obtained by the official or reported methods, showing no significant difference with respect to accuracy and precision at p?=?0.05.     

Synthetic Routes to Pyrazole‐3(5)‐carboxylates

The data on the synthetic methods of the pyrazole‐3(5)‐carboxylates published over the last years are reviewed here for the first time.     

First-principles investigations of iridium low index surfaces

We report density functional theory (DFT) calculations for the surface energy, work function, and interlayer spacings for Ir(1 1 1), Ir(1 0 0), and Ir(1 1 0) surfaces using pseudopotential method and plane waves basis set. We investigate the convergence of the surface energy as a function of the number of layers in the slab for the Ir(1 0 0) surface. The results show that the surface energies calculated using the bulk total energies obtained by a fit to a series of slab total energies converge within 0.01 J/m². We also investigate the convergence of the work function and interlayer spacings as a function of the number of layers in the slab, for the Ir(1 0 0) surface. Employing the local-density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange correlation functional, we obtained a very good agreement of the calculated surface energies and work functions with experimental results. For the studied surfaces, the calculations give interlayer relaxations that are in an excellent agreement with available low-energy electron diffraction (LEED) analysis. Furthermore, we discuss the performance of the LDA and GGA for the exchange correlation functional in describing the various surface properties. The results show that calculations using GGA give results that are in a better agreement with experiment than the LDA.     

A facile synthesis and antioxidant evaluation of conjugated 8-azacoumarins based on DFT parameters

A series of 8-azacoumarin, naphthyridine, and dioxazphenalene derivatives bearing conjugated moieties were intended and prepared by a concise and smooth approach using grinding and ultrasonic irradiation. A sustainable one pot reactions have emerged and progressed smoothly as an efficient and eco-safe methods in solvent less organic synthesis. The desired products were obtained in high yields, and the structures of all products were established on the basis of spectroscopic data and elemental analysis. Using the density functional theory (DFT) realized the electronic and structure characterization of synthesized azacoumarin. These heterocyclic compounds are chemically stable and are tested as antioxidants. Antioxidant potential was assessed using ABTS, and anti-hemolytic activity was evaluated by induced peroxide hemolysis. They gave good antioxidant results that showed potency ranging from good azacoumarin analogues 8 , 9 , 13 , 17 , and 20 , among compounds, showed much potency than that of commercial ascorbic acid.     

A validated enantioselective HPLC assay of dexibuprofen in dexibuprofen tablet formulations

A high-performance liquid chromatography-diode array detector (HPLC-DAD) method was developed and validated for the quantitation of dexibuprofen in dexibuprofen tablets using ovomucoid chiral stationary phase (Ultron ES-OVM). The mobile phasewas composed of 0.025 M potassium phosphate dibasic (pH 4.5)-methanol-ethanol (85:10:5 v/v/v). The method was validated for specificity, linearity, range, accuracy, precision and robustness. The method was enantiomerspecific for the determination of dexibuprofen [S-(+)-isomer ibuprofen] in the presence of R-(-)-isomer ibuprofen in bulk drug, pharmaceutical dosage form and under stress degradation. The method was linear over the range 15-35 mg/mL with r2 = 0.9995; accuracy and precision were acceptable with %RSD < 2.0%. The method was found to be specific, precise, accurate, robust and stability-indicating, and can be successfully applied for the routine analysis of dexibuprofen in bulk drug and pharmaceutical dosage form.     

Coordination chemistry of gold(II) with amidinate,thiolate and ylide ligands

Various reagents such as Cl₂, Br₂, I₂, benzoyl peroxide and CH₃I add to the dinuclear gold(I) amidinate complex [Au₂(2,6-Me₂Ph-form)₂] to form oxidative-addition gold(II) metal–metal bonded complexes. The gold–gold distance in the dinuclear complex decreases upon oxidative-addition with halogens from 2.7 to 2.5 Å, similar to observations made with dithiolate and ylide ligands. The sodium salt of the guanidinate Hhpp ligand, Hhpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine reacts with (THT)AuCl in THF or CH₂Cl₂ to form a Au(II) complex, [Au₂(hpp)₂Cl₂], either by solvent oxidation or disproportionation of the Au(I) to Au(II) and the metal. Density functional theory (DFT) and MP2 calculations on [Au₂(hpp)₂Cl₂] find that the highest occupied molecular orbital (HOMO) is predominately hpp and chlorine-based with some Au–Au δ* character. The lowest unoccupied molecular orbital (LUMO) has metal-to-ligand (M–L) and metal-to-metal (M–M) σ* character (approximately 50% hpp/chlorine, and 50% gold). The charge-transfer character of the deeply colored solutions is observed in all the oxidative-addition products of the dinuclear gold(II) nitrogen ligands. This contrasts with the colors of the gold(II) ylide oxidative-addition products which are pale yellow. The colors of the crystalline gold(II) nitrogen complexes are dark orange to brown. This review will focus on the chemistry of gold(II) with nitrogen ligands and compare this with the well reviewed chemistry of gold(II) thiolate and ylide complexes.     

Synthesis and antiviral activity of new indole-based heterocycles

New 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine and 1,3-thiazole derivatives incorporating indole nucleus were prepared using 3-acetylindole as precursor and evaluated for their antiviral activity against herpes simplex type 1 (HSV-1).