Microwave assisted low temperature synthesis of sodium zirconium phosphate (NaZr<Subscript>2</Subscript>P<Subscript>3</Subscript>O<Subscript>12</Subscript>)

Sodium zirconium phosphate [NaZr₂P₃O₁₂], a potential ceramic matrix for fixation of high level nuclear waste, was synthesized by heating the mixture of sodium carbonate [Na₂CO₃], zirconyl nitrate hydrate [ZrO(NO₃)₂·5H₂O] and ammonium dihydrogen phosphate [NH₄H₂PO₄] in air, in a resistance heated furnace and a microwave heating system respectively in the temperature range 450 to 650°C. The mixture heated for 1 h in a resistance furnace at 450°C yielded a poorly crystalline NaZr₂P₃O₁₂ [NZP]. Increasing the temperature to 650°C produced a highly crystalline product. The same mixture heated in a microwave oven at 450°C for 1 h however, yielded the most crystalline NZP.In an alternate method, the mixture of sodium dihydrogen phosphate (NaH₂PO₄), zirconium dioxide (ZrO₂) and diammonium hydrogen phosphate [(NH₄)₂HPO₄] heated in resistance furnace at 650°C for the same period did not react in air. It also did not yield the pure product at 450°C when heated in microwave assembly for 1 h.The authors thank the Board of Research in Nuclear Sciences (BRNS) of the Department of Atomic Energy (DAE) for the financial support for this work under the project No. 2000/37/19/BRNS/1959 dtd09-02-02.     

Engineered protein cages for nanomaterial synthesis

Self-assembled particles of genetically engineered human L subunit ferritin expressing a silver-binding peptide were used as nanocontainers for the synthesis of silver nanoparticles. The inner cavity of the self-assembled protein cage displays a dodecapeptide that is capable of reducing silver ions to metallic silver. This chimeric protein cage when incubated in the presence of silver nitrate exhibits the growth of a silver nanocrystal within its cavity. Our studies indicate that it is possible to design chimeric cages, using specific peptide templates, for the growth of other inorganic nanoparticles.     

Pulse-radiolysis studies on 4-pyridinemethanol and 4-pyridinecarboxaldehyde in aqueous solutions: dimer radical anion formation in the case of 4-pyridinecarboxaldehyde

Reactions of e _aq ^– , H atom and OH radicals with 4-pyridinemethanol (4-PM) and 4-pyridinecarboxaldehyde (4-PCA) have been studied at various pH values using the pulse radiolysis technique. Reaction of e _aq ^– with 4-PM and 4-PCA leads to the formation of pyridinyl and ketyl radicals of 4-PM and 4-PCA, respectively. Ketyl radicals formed from 4-PCA react with the parent molecule to give a dimeric radical species. At pH 7, the equilibrium constant for the dimer formation was determined to be 13 500 M^-1. At pH 13 also dimer radical formation was observed. Reaction of e _aq ^– with 4-PM was found to give highly reducing pyridinyl radicals. Reaction of OH radicals with 4-PM gives a mixture of species,viz., OH adducts and radicals formed by H-atom abstraction from the –CH₂OH moiety. Radicals formed by H-atom abstraction reaction from 4-PM were found to be reducing in nature. O^– radicals were found to react with 4-PM exclusively by H-abstraction pathway.     

Synthesis of Diquinolineno[1,3,7,9]Tetraazacyclododecine-7, 15 (14H, 16H)-Dibenzene,and DNA Binding Studies of Macrocyclic Co(II), Cu(II) Complexes: As New Class of Antimicrobial Agent

The synthesis of macrocyclic ligand, diquinolineno[1,3,7,9]tetraazacyclododecine-7, 15 (14H, 16H)-dibenzene(L), is described. The metal complexes of the type [MLX₂], where (M = Co(II) (1), Cu(II) (2) and X = (Cl), have been synthesized by the reaction of ligand(L) with the corresponding metal salts, and characterized by elemental analysis, FT-IR, ¹H-NMR and electronic spectra. The binding property of the complexes with CT-DNA was studied by absorption spectra, viscosity measurements, as well as thermal denaturation studies. The absorption spectral results indicate that the complexes (1) and (2) are binds with base pairs of DNA. The intrinsic binding constant K_b had the value 3.8 × 10⁴M ^?1 for (1 Chappell, L. L., Voss, A. D. and Morrow, J. R. 1998. Inorg. Chem., 37(16): 3989–3998.  [Google Scholar]) and 3.3 × 10⁴ M^?1 for (2), respectively, in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2. The viscosity measurement results show the viscosity of sonicated rod-like DNA fragments increased when the complex were added to the solution of calf thymus-DNA. The synthesized ligand and its metal complexes have been screened for antibacterial and antifungal activities.     

Synthesis and spectroscopic characterization of transition metal complexes derived from novel benzofuran hydrazone chelating ligand: DNA cleavage studies and antimicrobial activity with special emphasis on antituberculosis

Mononuclear divalent complexes of Co, Ni, Cu and Zn derived from a benzofuran‐based novel hydrazone tridentate ligand were synthesized and characterized using various spectroscopic methods. Elemental analysis reveals that the metal‐to‐ligand ratio is 1:2 which is supported by mass spectrometry results. Conductivity measurements suggest that all the complexes are non‐electrolytic in nature. The ligand and complexes were evaluated for their antimicrobial potency. Bioassay of all hydrazone chelates shows enhanced activity as compared to that of the ligand. The complex with cobalt ion as the metal centre shows better activity against fungi than the standard. Also, ligand and complexes were screened for antituberculosis activity; some analogues (Ni, Cu, Zn) are eight times more active than the standard. Both ligand and complexes show moderate ability to cleave calf thymus DNA. Copyright © 2015 John Wiley & Sons, Ltd.     

Tandem mass spectrometry of kahalalides: identification of two new cyclic depsipeptides, kahalalide R and S from Elysia grandifolia

Spectra obtained using electrospray ionization mass spectrometry (ESI-MS) of the mollusk Elysia grandifolia showed a cluster of molecular ion peaks centered at a molecular mass of 1478 Da (kahalalide F, an anticancer agent). Two new molecules, kahalalide R (m/z 1464) and S (m/z 1492) were characterized using tandem mass spectrometry. The mass differences of 14 Da suggest that they are homologous molecules. In addition, previously identified kahalalide D and kahalalide G are also reported. However, the ESI-MS of the mollusk's algal diet Bryopsis plumosa showed the presence of only kahalalide F. The amino acid sequences of kahalalide R and S are proposed using collision-induced dissociation (CID) experiments of singly and doubly charged molecular ions and by comparison with the amino acid sequence of kahalalide F. The pathway is presented for the loss of amino acid residues in kahalalide F. It is observed that there is sequential loss of amino acids in the linear peptide chain, but in the cyclic part the ring opens at the amide bond rather than at the lactone linkage, and the loss of amino acid residues is not sequential. The CID experiment of the alkali-metal-cationized molecular ions shows that the sodium and potassium ions coordinate to the amide nitrogen/oxygen in the linear peptide chain of the molecule and not to the lactone oxygen of the lactone. In the case of kahalalide D, CID of the protonated peptide opens the depsipeptide ring to form a linear peptide with acylium ion, and fragment ion signals indicate losses of amino acids in sequential order. In this study, tandem mass spectrometry has provided the detailed information required to fully characterize the new peptides.     

Optical Modulation of Azobenzene‐Modified Peptide for Gold Surface Binding

The ability to precisely and remotely modulate reversible binding interactions between biomolecules and abiotic surfaces is appealing for many applications. To achieve this level of control, an azobenzene‐based optical switch is added to nanoparticle‐binding peptides in order to switch peptide conformation and attenuate binding affinity to gold surfaces via binding and dissociation of peptides.     

Simultaneous determination of novel β-lactamase inhibitor WCK 4234 and Meropenem in dog plasma by LC–MS/MS and its application to preclinical pharmacokinetic study

A precise and accurate liquid chromatography–tandem mass spectrometric (LC–MS/MS) bioanalytical method has been developed and validated for the simultaneous quantification of WCK 4234 and meropenem (MEM) in dog plasma. Protein precipitation using acetonitrile was employed as a sample preparation approach. Cefepime was used as an internal standard. The developed method was selective, sensitive (limit of quantification, 0.075 μg/ml for both drugs), accurate (recovery > 90%), precise (CV < 10%) and linear (r² ≥ 0.99, concentration range 0.075–120 μg/ml for both analytes). The developed method was successfully applied for the determination of both drugs in plasma to assess the pharmacokinetics in beagle dogs. WCK 4234 + MEM in a 1:1 ratio at 15 + 15 and 30 + 30 mg/kg doses were administered by the intravenous route. The mean plasma concentration and area under the concentration–time curve of WCK 4234 ranged from 38.3 to 77.4 μg/ml and from 47.8 to 77.1 μg h/ml, respectively, and the values for MEM ranged from 52.2 to 115.3 μg/ml and 70.5 to 133.6 μg h/ml respectively. The elimination half-life of WCK 4234 and MEM was around 0.8 h.     

Investigation on Impurity Profiling and Degradation Behavior of WCK 771

Chromatographia - WCK 771 is a novel antibacterial drug recently launched in India for the treatment of acute bacterial skin and skin structure infections (ABSSSI). This report describes...