Solvent hydrogen bonding and structural effects on the reaction of 2‐halo‐5‐nitropyridines with parasubstituted anilines in dimethylsulfoxide/acetonitrile mixtures

Substitution reactions of some parasubstituted anilines with 2‐chloro‐5‐nitropyridine and 2‐bromo‐5‐nitropyridine were carried out conductometrically in dimethylsulfoxide/acetonitrile mixtures. The correlation of second order rate constants with Hammett's substituent constants yields a fairly linear straight line with a negative slope. The correlation of rate data with Kamlet–Taft's solvatochromic parameters is excellent (100R²= 97%) in both the substrates. The solvation model proposed is well supported by the solvatochromism exhibited by aniline in the solvent mixture under investigation. The molar extinction coefficient (ε_max ) of aniline varies appreciably up to ～25% with the change in composition of the mixture. The multivariate correlation analysis of ε_max (with α, β, π*) suggests that the solvation around NH₂ moiety of aniline through hydrogen bond donor (HBD) property is found to be dominant in the solvation process and consequently in altering the rate. The observation is that the dominance of HBD property in solvation is further confirmed by the cyclic voltammetric oxidation of aniline in the solvent mixture. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 409–417, 2011     

Architecture of small RNA viruses

Symmetric organization of biological macromolecules is necessary for certain structural and functional requirements of living cells. The mechanisms by which biomolecules assemble unambiguously into unique structures has been a central theme of investigation in molecular biology. Simple viruses consist of a nucleic acid core which codes for the genetic information surrounded and protected by a protein coat or capsid. In a large majority of the cases, the protein coats possess exact icosahedral symmetry. Developments in experimental X-ray crystallography and computer technology has led recently to the elucidation of the architecture of several viruses. Systematic studies on the structure of the protein subunits, their location and orientation on the icosahedral capsid, and the details of interaction between subunits has provided some insights into the mechanisms of error free virus assembly. However, the structures of even the simplest viruses are sufficiently complex and do not lead to complete understanding of the pathway of assembly by an examination of the final structure. The current state of research in this fast advancing area is briefly reviewed.     

Solvent hydrogen bonding and structural effects on nucleophilic substitution reactions: Part 3. Reaction of benzenesulfonyl chloride with anilines in benzene/propan‐2‐ol mixtures

Substitution reactions of 13 para‐ and meta‐substituted anilines with benzenesulfonyl chloride in varying mole fractions of benzene in propan‐2‐ol have been investigated conductometrically. The second‐order rate constants correlate well with pK_a values of anilines and with the Hammett's equation. The negative Hammett reaction constant indicates the formation of an electron‐deficient transition state. The rate data correlate satisfactorily with macroscopic solvent parameters such as relative permittivity, ε_r, and polarity, E_T^N. Correlation of rate data with Kamlet–Taft solvatochromic parameters (α, β, π*) suggests that both the specific and nonspecific solute–solvent interactions influence the reactivity. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 657–663, 2007     

Solvent and substituent effects on the electrochemical oxidation of para‐ and meta‐substituted anilines

Electrochemical oxidation of 15 para‐ and meta‐substituted anilines in different mole fractions of water in 2‐methylpropan‐2‐ol has been investigated in the presence of 0.1 M sulfuric acid as a supporting electrolyte. The oxidation potential data of anilines correlate well with the Brown–Okamoto's substituent constants affording a negative reaction constant. The effect of para‐ and meta‐substituents on the oxidation potential confirms to Swain's F and R, affording negative reaction constants. The oxidation potential values also correlate satisfactorily with macroscopic solvent parameter such as relative permittivity, ε_r. The results of Kamlet–Taft multiple correlation analysis show that specific solute–solvent interactions play a dominant role in governing the reactivity. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 289–297, 2007     

Identification of potential CRAC channel inhibitors: Pharmacophore mapping, 3D-QSAR modelling,and molecular docking approach

Upregulation of store-operated Ca²⁺ influx via ORAI1, an integral component of the CRAC channel, is responsible for abnormal cytokine release in active rheumatoid arthritis, and therefore ORAI1 has been proposed as an attractive molecular target. In this study, we attempted to predict the mechanical insights of ORAI1 inhibitors through pharmacophore modelling, 3D-QSAR, molecular docking and free energy analysis. Various hypotheses of pharmacophores were generated and from that, a pharmacophore hypothesis with two hydrogen bond acceptors, one hydrogen bond donor and two aromatic rings (AADRR) resulted in a statistically significant 3D-QSAR model (r² = 0.84 and q² = 0.74). We believe that the obtained statistical model is a reliable QSAR model for the diverse dataset of inhibitors against the IL-2 production assay. The visualization of contours in active and inactive compounds generated from the 3D-QSAR models and molecular docking studies revealed major interaction with GLN108, HIS113 and ASP114, and interestingly, these residues are located near the Ca²⁺ selectivity filter region. Free energy binding analysis revealed that Coulomb energy, van der Waals energy and non-polar solvation terms are more favourable for ligand binding. Thus, the present study provides the physical and chemical requirements for the development of novel ORAI1 inhibitors with improved biological activity.     

Antidiabetic Activity of Ethanolic Extract of Zaleya decandra in Alloxan-Induced Diabetic Rats

Diabetes mellitus is a complex disorder that disturbs the metabolism of carbohydrates, fats, and proteins. Medicinal plants play an important role in the management of diabetes mellitus. The present study was aimed to evaluate the antidiabetic potential of Zaleya decandra roots on alloxan-induced diabetes in rats. Oral administration of ethanolic extract of the root (200 mg/kg body weight/day) for 15 days restored the levels of glucose, cholesterol, triglycerides, total proteins, urea, creatinine, lipid peroxidation level, and antioxidant enzymes significantly in diabetic rats. Histopathological studies showed significant changes like necrosis and degeneration in the liver and pancreas of alloxan-induced diabetic rats. Also these histopathological abnormalities were found to be normalized after treatment with Z. decandra extract. The efficacy of the root extract was found to be equivalent when compared to the standard hypoglycemic drug glibenclamide (1.25 mg/kg body weight/day, orally) in diabetic rats.     

Synthesis of zinc oxide nanoparticles (ZnO NPs) using pure bioflavonoid rutin and their biomedical applications: antibacterial,antioxidant and cytotoxic activities

Research on Chemical Intermediates - The present study reports an eco-friendly green synthesis of zinc oxide nanoparticles (ZnO NPs) using the bioflavonoid rutin. The synthesized ZnO NPs were...     

Facile synthesis of low dimensional CuO nanostructures and their gas sensing applications

A simple and cost effective hydrothermal method has been employed to synthesis morphology controlled pure and Cr doped (4 and 8 at. %) CuO nanostructures. Crystalline purity and structure of the nanostructures were validated by X‐ray diffraction and Retvield analyses. Field emission scanning electron microscopy revealed the evolution of rod‐like, sheet‐like and boat‐like morphologies for pure, 4 and 8 at. % Cr doped CuO nanostructures respectively. The optical band gap estimated using the K‐M function plot from diffused reflectance spectroscopy showed a shift in band gap from 1.68 to 1.90 eV with respect to Cr concentration. The synthesized CuO nanostructures were investigated for the efficient room temperature gas sensing of ammonia, ethanol and methanol vapours under different concentrations (100‐600 ppm). The 8 at. % Cr doped CuO nano‐boats showed enhanced gas sensitivity than other CuO nanostructures owing to their typical morphology, larger surface area and related properties.