Monitoring redox-sensitive paramagnetic contrast agent by EPRI, OMRI and MRI

A comparative study of tissue redox-status imaging using commonly used redox sensitive nitroxides has been carried out using electron paramagnetic resonance imaging (EPRI), Overhauser magnetic resonance imaging (OMRI) and conventional T(1)-weighted magnetic resonance imaging, MRI. Imaging studies using phantoms of different nitroxides at different concentration levels showed that EPRI and OMRI sensitivities were found to be linearly dependent on line width of nitroxides up to 2 mM, and the enhancement in MRI intensity was linear up to 5 mM. The sensitivity and resolution of EPRI and OMRI images depended significantly on the line width of the nitroxides whereas the MRI images were almost independent of EPR line width. Reduction of the paramagnetic 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (3CP) by ascorbic acid (AsA) to the diamagnetic by hydroxylamine was monitored from a sequence of temporal images, acquired using the three imaging modalities. The decay rates determined by all the three modalities were found to be similar. However the results suggest that T(1)-weighted MRI can monitor the redox status, in addition to providing detailed anatomical structure in a short time. Therefore, a combination of MRI with nitroxides as metabolically responsive contrast agents can be a useful technique for the in vivo imaging probing tissue redox status.     

Binary Effects of Gynostemma Gold Nanoparticles on Obesity and Inflammation via Downregulation of PPARγ/CEPBα and TNF-α Gene Expression

Nanoscience is a multidisciplinary skill with elucidated nanoscale particles and their advantages in applications to various fields. Owing to their economical synthesis, biocompatible nature, and widespread biomedical and environmental applications, the green synthesis of metal nanoparticles using medicinal plants has become a potential research area in biomedical research and functional food formulations. Gynostemma pentaphyllum (GP) has been extensively used in traditional Chinese medicine to cure several diseases, including diabetes mellitus (DM). This is the first study in which we examined the efficacy of G. pentaphyllum gold nanoparticles (GP-AuNPs) against obesity and related inflammation. GP extract was used as a capping agent to reduce Au²⁺ to Au⁰ to form stable gold nanoparticles. The nanoparticles were characterized by using UV–VIS spectroscopy, and TEM images were used to analyze morphology. In contrast, the existence of the functional group was measured using FTIR, and size and shape were examined using XRD analysis. In vitro analysis on GP-AuNPs was nontoxic to RAW 264.7 cells and 3T3-L1 cells up to a specific concentration. It significantly decreased lipid accumulation in 3T3-L1 obese and reduced NO production in Raw 264.7 macrophage cells. The significant adipogenic genes PPARγ and CEPBα and a major pro-inflammatory cytokine TNF-α expression were quantified using RT-PCR. The GP-AuNPs decreased the face of these genes remarkably, revealing the antiadipogenic and anti-inflammatory activity of our synthesized GP-AuNPs. This study represents thorough research on the antiobesity effect of Gynostemma pentaphyllum gold nanoparticles synthesized using a green approach and the efficacy instead of related inflammatory responses.     

One-pot synthesis of methyl piperazinyl–quinolinyl nicotinonitrile derivatives under microwave conditions and molecular docking studies with DNA

Derivatives of methyl piperazinyl–quinolinyl nicotinonitrile were synthesised by one-pot method under microwave conditions. This was achieved using the Knoevenagel condensation reaction. The novel derivatives described above were purified by column chromatography and characterised by FT-IR, ¹H, ¹³C, 2D-NMR and HRMS spectroscopic techniques. Furthermore, molecular docking was used to determine the binding sites of DNA with selected compounds. The synthetic method developed in this study showed several advantages including simplicity, high yield of products, coupled with safety and a short reaction time of 15 min.     

A one dimensional analysis of convective drying of porous materials

A one-dimensional finite element analysis has been carried out to study temperature and moisture variation of porous materials during convective drying. The predicted results for brick and mortar with constant transport properties agree with available experimental data. Henderson’s modified equation has been used to obtain the desorption data for the materials.     

General and selective synthesis of primary amines using Ni-based homogeneous catalysts

The development of base metal catalysts for industrially relevant amination and hydrogenation reactions by applying abundant and atom economical reagents continues to be important for the cost-effective and sustainable synthesis of amines which represent highly essential chemicals. In particular, the synthesis of primary amines is of central importance because these compounds serve as key precursors and central intermediates to produce value-added fine and bulk chemicals as well as pharmaceuticals, agrochemicals and materials. Here we report a Ni-triphos complex as the first Ni-based homogeneous catalyst for both reductive amination of carbonyl compounds with ammonia and hydrogenation of nitroarenes to prepare all kinds of primary amines. Remarkably, this Ni-complex enabled the synthesis of functionalized and structurally diverse benzylic, heterocyclic and aliphatic linear and branched primary amines as well as aromatic primary amines starting from inexpensive and easily accessible carbonyl compounds (aldehydes and ketones) and nitroarenes using ammonia and molecular hydrogen. This Ni-catalyzed reductive amination methodology has been applied for the amination of more complex pharmaceuticals and steroid derivatives. Detailed DFT computations have been performed for the Ni-triphos based reductive amination reaction, and they revealed that the overall reaction has an inner-sphere mechanism with H₂ metathesis as the rate-determining step.

A Ni-triphos based homogeneous catalyst enabled the synthesis of all kinds of primary amines by reductive amination of carbonyl compounds with ammonia and hydrogenation of nitroarenes.     

Spin trapping by 5-carbamoyl-5-methyl-1-pyrroline N-oxide (AMPO): theoretical and experimental studies

The nitrone 5-carbamoyl-5-methyl-1-pyrroline N-oxide (AMPO) was synthesized and characterized. Spin trapping of various radicals by AMPO was demonstrated for the first time by electron paramagnetic resonance (EPR) spectroscopy. The resulting spin adducts for each of these radicals gave unique spectral profiles. The hyperfine splitting constants for the superoxide adduct are as follows: isomer I (80%), a(nitronyl)(-)(N) = 13.0 G and a(beta)(-)(H) = 10.8 G; isomer II (20%), a(nitronyl)(-)(N) = 13.1 G, a(beta)(-)(H) = 12.5 G, and a(gamma)(-)(H) = 1.75 G. The half-life of the AMPO-O(2)H was about 8 min, similar to that observed for EMPO but significantly shorter than that of the DEPMPO-O(2)H with t(1/2) approximately 16 min. However, the spectral profile of AMPO-O(2)H at high S/N ratio is distinguishable from the spectrum of the (*)OH adduct. Theoretical analyses using density functional theory calculations at the B3LYP/6-31+G//B3LYP/6-31G level were performed on AMPO and its corresponding superoxide adduct. Calculations predicted the presence of intramolecular H-bonding in both AMPO and its superoxide adduct. The H-bonding interaction was further confirmed by an X-ray structure of AMPO, and of the novel and analogous amido nitrone 2-amino-5-carbamoyl-5-methyl-1-pyrroline N-oxide (NH(2)-AMPO). The thermodynamic quantities for superoxide radical trapping by various nitrones have been found to predict favorable formation of certain isomers. The measured partition coefficient in an n-octanol/buffer system of AMPO was similar to those of DMPO and DEPMPO. This study demonstrates the suitability of the AMPO nitrone for use as a spin trap to study radical production in aqueous systems.     

A modified catalytic-photometric method for the determination of vanadium in chloride rich hydro-geochemical samples

The vanadium content in chloride rich hydrogeochemical samples has been determined through a modification in the existing standard gallic acid oxidation method which has severe interference problem from halides. The modification incorporates a preliminary fume-drying of the sample aliquot with a mixture of perchloric and sulphuric acids. This ensures total removal of halides and hence their interference. The estimation is completed as per the standard method after taking the sample in 10 ml of 1% nitric acid. Also mercuric nitrate addition which forms a part of the standard procedure to prevent halide interference, is also dispensed with keeping in view the toxic nature of mercury. The method has been tried on a number of samples having varying chloride content. The results obtained compare well with the standard PAR method. The method can be used to determine vanadium down to 1 ppb. The relative standard deviation obtained for vanadium contents in the range 400–10 ppb is in the range 4–8.2%.     

Rare earth transition metal sulfides,LnMS3

Ternary rare earth transition metal sulfides LnMS₃ with Ln = La, Nd, and Gd, and M = V and Cr; as well as Ln = La and M = Mn, Fe, Co, and Ni have been prepared and characterized. The vanadium and chromium sulfides crystallize in a monoclinic layer structure isotypic with LaCrS₃, while the other LnMS₃ sulfides crystallize in a hexagonal structure. Chemical shifts of the metal K-absorption edge and XPS binding energies of core levels indicate that the transition metal is trivalent in the V and Cr sulfides, while it is divalent in the Mn, Fe, Co, and Ni sulfides. Electrical and magnetic properties of the sulfides are discussed in terms of their structures and the electronic configurations of the transition metal ions.     

Thermophysical properties of 1-hexyl-3-methyl imidazolium based ionic liquids with tetrafluoroborate, hexafluorophosphate and bis(trifluoromethylsulfonyl)imide anions

The thermophysical properties of 1-hexyl-3-methyl imidazolium based hydrophobic room temperature ionic liquids (RTILs); with tetrafluoroborate (BF₄), hexafluorophosphate (PF₆), and bis(trifluoromethylsulfonyl)imide (Tf₂N) anions, namely density ρ (298.15 to 348.15) K, dynamic viscosity η (288.2 to 348.2) K, surface tension σ (298.15 to 338) K, and refractive index n_D (302.95 to 332.95) K have been measured. The coefficients of thermal expansion α_p values were calculated from the experimental density data using an empirical correlation. The thermal stability of all ILs is also investigated at two different heating rates (10 and 20) °C · min⁻¹) using thermogravimetric analyzer (TGA). The experimental results presented in this study reveal that the choice of anion type shows the most significant effect on the properties of ILs. The chloride and water contents of ILs (as impurities) are also investigated and reported in the present work.