Multidimensional solid-state NMR spectroscopy of plant cell walls

Plant biomass has become an important source of bio-renewable energy in modern society. The molecular structure of plant cell walls is difficult to characterize by most atomic-resolution techniques due to the insoluble and disordered nature of the cell wall. Solid-state NMR (SSNMR) spectroscopy is uniquely suited for studying native hydrated plant cell walls at the molecular level with chemical resolution. Significant progress has been made in the last five years to elucidate the molecular structures and interactions of cellulose and matrix polysaccharides in plant cell walls. These studies have focused on primary cell walls of growing plants in both the dicotyledonous and grass families, as represented by the model plants Arabidopsis thaliana, Brachypodium distachyon, and Zea mays. To date, these SSNMR results have shown that 1) cellulose, hemicellulose, and pectins form a single network in the primary cell wall; 2) in dicot cell walls, the protein expansin targets the hemicellulose-enriched region of the cellulose microfibril for its wall-loosening function; and 3) primary wall cellulose has polymorphic structures that are distinct from the microbial cellulose structures. This article summarizes these key findings, and points out future directions of investigation to advance our fundamental understanding of plant cell wall structure and function.     

Novel bioactive constituents from Enhydra fluctuans LOUR

A novel bioactive isoflavone glycoside 4',5,6,7-tetrahydroxy-8-methoxyisoflavone-7-O-beta-D-galactopyranosyl-(1 --> 3)-O-beta-D-xylopyranosyl-(1 --> 4)-O-alpha-l-rhamnopyranoside from the methanolic extract of the leaves of Enhydra fluctuans Lour. Its structure A was elucidated by various spectral analysis and chemical degradations. This compound exhibited microbial activity against various bacteria and fungi.     

Design,synthesis, and antimicrobial evaluation of some nifuroxazide analogs against nosocomial infection

A series of 10 p-substitutedbenzoylmethylene hydrazide derivatives 4a-j were synthesized by protecting carboxylic group of 4-hydroxybenzoic acid using methanol and sulfuric acid than reacting it with hydrazide to form 4-hydroxybenzohydrazide followed by reacting with a variety of aldehydes and evaluated for their activity against nosocomial infection. All the synthesized compounds were characterized by Fourier-transform infrared (FT-IR), ¹H nuclear magnetic resonance (NMR), and mass spectral data. The in vitro antimicrobial potential of synthesized compounds was estimated against prominent strains of nosocomial pathogens (Staphylococcus aureus, Escherichia coli, and Aspergillus niger). The antimicrobial evaluation revealed compounds 4b , 4c , 4d , 4e , 4f , and 4j to be the most active compounds of the series with IC₅₀ value for antibacterial in the range 0.39 to 0.75 μM/mL. Furthermore, the in vitro cytotoxic potential of the compounds was appraised by hemolytic assay. The results showed that some of the synthesized compounds exhibited marked activity.     

Synthesis ofN1‐3‐{(4‐Substituted aryl‐3‐chloro‐2‐oxo‐azetidine)‐iminocarbamyl}‐propyl‐6‐nitroindazole Derivatives and Their Biological Significance

Synthesis ofN¹‐3‐{(4‐substitute daryl‐3‐chloro‐2‐oxo‐azetidine)‐iminocarbamyl}‐propyl‐6‐nitroindazole 4a – 4s was conducted by a conventional method. All the compounds were synthesized and characterized by IR, ¹H NMR, ¹³C NMR, FAB‐Mass techniques and chemical methods. All the final synthesized compounds were evaluated for their antimicrobial activity and antitubercular activity with MIC values against some selected microorganisms.     

Synthesis and Biological Study of Some 4-oxo-Thiazolidine Derivatives of 2-Aminothiazole

Conventional and microwave assisted synthesis of new series of N‐[2‐{2‐(substituted phenyl)‐4‐oxo‐5‐(substituted benzylidene)‐1,3‐thiazolidine}‐iminoethyl]‐2‐aminothiazole 5a–5m have been developed. The cycloaddition reaction of thioglycolic acid with N‐{2‐(substituted benzylidenehydrazino)‐ethyl}‐2‐aminothiazole 3a–3m in the presence of anhydrous ZnCl₂ afforded new heterocyclic compounds N‐[2‐{2‐(substituted phenyl)‐4‐oxo‐1,3‐thiazolidine}‐iminoethyl]‐2‐aminothiazole 4a–4m . The later product on treatment with several selected substituted aromatic aldehydes in the presence of C₂H₅ONa undergoes Knoevenagel reaction to yield 5a–5m . The structures of compounds 1 , 2 , 3a–3m , 4a–4m and 5a–5m were confirmed by IR, ¹H NMR, ¹³C NMR, FAB‐Mass and chemical analysis. All above compounds were screened for their antimicrobial activities against some selected bacteria and fungi and antituberculosis study against M. tuberculosis.     

A critical analysis of urea transporter B inhibitors: molecular fingerprints,pharmacophore features for the development of next-generation diuretics

Molecular Diversity - Urea transporter is a membrane transport protein. It is involved in the transferring of urea across the cell membrane in humans. Along with urea transporter A, urea...     

Structural phase transitions and elastic properties of zirconia

The structural phase transformations in various phases (monoclinic, ortho I, ortho II, and tetragonal) of zirconia (ZrO₂) have been investigated using an effective interionic interaction potential. The cohesive energy, the equation of state, and the elastic properties of these phases have also been studied and found to reproduce well the experimentally observed data for almost all the phases of zirconia ceramics.     

Au–Pt bimetallic nanoparticles supported on nest-like MnO2: synthesis and application in HCHO decomposition

Major research issues in oral protein delivery include the stabilization of protein in delivery devices which could increase its oral bioavailability. The study deals with development of oral insulin delivery system utilizing biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles and modifying its surface with Concanavalin A to increase lymphatic uptake. Surface-modified PLGA nanoparticles were characterized for conjugation efficiency of ligand, shape and surface morphology, particle size, zeta potential, polydispersity index, entrapment efficiency, and in vitro drug release. Stability of insulin in the developed formulation was confirmed by SDS-PAGE, and integrity of entrapped insulin was assessed using circular dichroism spectrum. Ex vivo study was performed on Wistar rats, which exhibited the higher intestinal uptake of Con A conjugated nanoparticles. In vivo study performed on streptozotocin-induced diabetic rats which indicate that a surface-modified nanoparticle reduces blood glucose level effectively within 4?h of its oral administration. In conclusion, the present work resulted in successful production of Con A NPs bearing insulin with sustained release profile, and better absorption and stability. The Con A NPs showed high insulin uptake, due to its relative high affinity for non-reducing carbohydrate residues i.e., fucose present on M cells and have the potential for oral insulin delivery in effective management of Type 1 diabetes condition.     

Ion transport behavior in a new fast Ag ion conducting composite electrolyte system: 0.85[0.75AgI:0.25AgCl]:0.15CeO2

Investigations on ion transport behavior of a new fast Ag⁺ ion conducting composite electrolyte system: 0.85[0.75AgI:0.25AgCl]: 0.1CeO₂ are reported. An alternate host: ‘[0.75AgI:0.25AgCl] mixed system/solid solution’ has been used as first-phase host matrix salt, in place of the traditional host AgI, while the micron-size particles of an insulating and chemically inert CeO₂ as second-phase dispersoid. The soaking time, plays important role in determining the conductivity enhancement in the composite system. The system: 0.85[0.75AgI:0.25AgCl]:0.1CeO₂ prepared at soaking time ∼10 min. exhibited optimum conductivity:σ_rt ∼ 1.2 × 10⁻³ S cm⁻¹ at room temperature, which is an order of magnitude higher than that of the pure host. Structural characterization studies were performed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Temperature dependent measurement on the basic ionic parameters viz. conductivity (σ), ionic mobility (μ), mobile ion concentration (n), room temperature ionic transference number (t_ion) and ionic drift velocity (v_d) have been carried out on the system.