Gracilone,a new sesquiterpene lactone from Tanacetum gracile (Tansies)

The methanolic extract of the Tanacetum gracile afforded the isolation of new sesquiterpene lactone, named gracilone (1) along with four known compounds as 14α-taraxeran-3-one (2), 14α-taraxeran-3-ol (3), apigenin (4) and β-sitosterol (5). The structure of compound 1 was elucidated on the basis of 1D, 2D NMR and MS spectroscopic analysis. Antimicrobial, antioxidant and anticancer activities of all compounds were evaluated, from which gracilone (1) showed a moderate antibacterial activity, while apigenin (4) showed comparatively more antibacterial activity against both gram­positive and gram­negative tested strains.     

FTIR and Raman microspectroscopy of normal,benign, and malignant formalin-fixed ovarian tissues

Ovarian cancer is the sixth most common cancer among women worldwide, and mortality rates from this cancer are higher than for other gynecological cancers. This is attributed to a lack of reliable screening methods and the inadequacy of treatment modalities for the advanced stages of the disease. FTIR and Raman spectroscopic studies of formalin-fixed normal, benign, and malignant ovarian tissues have been undertaken in order to investigate and attempt to understand the underlying biochemical changes associated with the disease, and to explore the feasibility of discriminating between these different tissue types. Raman spectra of normal tissues indicate the dominance of proteins and lower contents of DNA and lipids compared to malignant tissues. Among the pathological tissues studied, spectra from benign tissues seem to contain more proteins and less DNA and lipids compared to malignant tissue spectra. FTIR studies corroborate these findings. FTIR and Raman spectra of both normal and benign tissues showed more similarities than those of malignant tissues. Cluster analysis of first-derivative Raman spectra in the 700–1700 cm⁻¹ range gave two clear groups, one corresponding to malignant and the other to normal+benign tissues. At a lower heterogeneity level, the normal+benign cluster gave three nonoverlapping subclusters, one corresponding to normal and two for benign tissues. Cluster analysis of second-derivative FTIR spectra in the combined spectral regions of 1540–1680 and 1720–1780 cm⁻¹ resulted into two clear clusters corresponding to malignant and normal+benign tissues. The cluster corresponding to normal+benign tissues produced nonoverlapping subclusters for normal and benign tissues at a lower heterogeneity level. The findings of this study demonstrate the feasibility of Raman and FTIR microspectroscopic discrimination of formalin-fixed normal, benign, and malignant ovarian tissues.     

Influence of Nd:Zn codoping in near-stoichiometric lithium niobate

Near-stoichiometric lithium niobate (SLN) crystals doped with up to 1.6 mol % Zn and codoped with various Nd concentrations in the melt (0.2, 0.5, 0.9, and 1.5 mol %) (Nd:Zn:SLN) are grown from 58.6 mol % Li(2)O using conventional Czochralski technique. Crystals are pulled at the rate of 0.35 mmh with seed rotation at 9 rpm. Concentrations of Zn and Nd in the crystal are varied by adding appropriate amounts of ZnO and Nd(2)O(3) to the starting composition. Unit cell parameters of the grown crystals are calculated by Rietveld refinement method using FULLPROFF software. Domain structure studies are carried out by chemical etching followed by microscopic examination. Dielectric studies reveal the existence of piezoelectric resonance at high frequencies. Enhancement in dielectric constant and tan delta in Nd doped samples has been attributed to the space charge polarization. Nd doped samples exhibit reduction in the relative permittivity after oxygen annealing. Transmission spectra of Nd:Zn:SLN crystals in the UV region exhibit blueshift in the cutoff wavelength. In Mid Infrared (MIR) region crystals doped with 1.6 mol % Zn have shift in the OH absorption peak from 2873 to 2833 nm. Judd-Ofelt analysis carried out on the absorption spectra of codoped crystal yields the lifetime of 104 mus for the metastable state (4)F(32). The branching ratio for the electronic transition from (4)F(32) to (4)I(112) is high compared to that for (4)F(32) to (4)I(132), indicating a higher emission cross section for the former transition. Laser damage threshold evaluated using 532 nm, 5 ns pulsed neodymium doped yttrium aluminum garnet laser, shows an increase by two orders of magnitude for crystals doped with 1.6 mol % Zn. Photorefractive damage threshold for these crystals shows an enhancement of four orders of magnitude due to increase in the photoconductivity.     

A computational characterization of boron-oxygen multiple bonding in HN=CH-CH=CH-NH-BO

Structures, relative energies, and bonding characteristics for various conformers of 3-imino-N-(oxoboryl)prop-1-en-1-amine, HN=CH-CH=CH-NH-BO, and the corresponding borocycle (-HN=CH-CH=CH-NH-B-)O are discussed using results from second-order M?ller-Plesset (MP2) perturbation theory with the Dunning-Woon correlation-consistent cc-pVDZ, aug-cc-pVDZ, and cc-pVTZ basis sets. These MP2 results are compared to those from computationally efficient density functional theory (DFT) calculations using the LDA, PBE, TPSS, BLYP, B3LYP, BVP86, OLYP, O3LYP, and PBE1PBE functionals in conjunction with the economical Pople-type 6-311++G(d,p) basis set to evaluate the suitability of these DFT/6-311++G(d,p) levels for use with larger boron-containing systems. The effects of an aqueous environment were incorporated into the calculations using COSMO methodology. The calculated boron-oxygen bond lengths, orbital compositions, and bond orders in all the (acyclic) HN=CH-CH=CH-NH-BO conformers were consistent with the presence of a boron-oxygen triple bond, similar to that found in H-BO and H2N-BO. The (-HN=CH-CH=CH-NH-B-)O borocycle is predicted to be planar (C2v symmetry), and it is approximately 30 kcal/mol lower in energy than any of the (acyclic) HN=CH-CH=CH-NH-BO conformers; the boron-oxygen bond in this borocycle has significant double bond character, a bonding scheme for which there has been only one experimental structure reported in the literature (Vidovic, D. ; et al. J. Am. Chem. Soc. 2005, 127, 4566- 4569).     

Antimicrobial peptides in burns and wounds

Burn-induced immunosuppression not only increases susceptibility to infection, but also predisposes burn patients to related adverse sequelae, including systemic inflammatory response syndrome and sepsis. Although burn-related immunosuppression is not fully understood, it is characterized by decreased T- and B-lymphocyte function and by impaired functions of circulating leukocytes and complement. Alterations in defensins, a family of cationic, naturally occurring antimicrobial peptides, may underlie these immune deficiency patterns. Defensins are considered important components of the innate immune system, as they inhibit bacterial, fungal, and viral colonization. They also chemoattract immature dendritic cells and T lymphocytes, recruit neutrophils, macrophages, and monocytes, modulate complement and adjuvant activity, and promote inflammation and wound healing. Infectious states are associated with upregulation of circulating defensins, which suggests an underlying antimicrobial role. In addition, data from our laboratory demonstrated diminished levels of certain defensins in burned tissue. The inference is that decreased defensin levels in burn injury may facilitate infection and subsequent sepsis. It may also alter functions of T- and B-lymphocytes, neutrophils, macrophages, and complement, thereby contributing to the pathophysiology of burn-related systemic inflammatory responses. This article is a comprehensive review on the role of antimicrobial peptides in burns and wounds.     

Kinetic investigations into the synthesis of disulphides via tetrathiomolybdate as a sulphur-transfer reagent

Kinetic and mechanistic aspects of the conversion of halides to disulphides using benzyl triethyl ammonium tetrathiomolybdate as sulphur-transfer reagent were investigated. The reaction follows a 1:1 stoichiometry with overall second-order kinetics and involves the formation of monosulphides in addition to disulphides. In the light of our observations, we propose a nucleophilic substitution: carbon–metal–carbon (S_N-CMC) reaction mechanism. The proposed mechanism, besides accounting for all of our experimental observations, also explains many aspects of such reactions that have been reported earlier by various groups.     

Effect of carrier concentration of InN on the transport behavior of InN/GaN heterostructure based Schottky junctions

We present the study involving the dependence of carrier concentration of InN films, grown on GaN templates using the plasma assisted molecular beam epitaxy system, on growth temperature. The influence of InN carrier concentration on the electrical transport behavior of InN/GaN heterostructure based Schottky junctions is also discussed. The optical absorption edge of InN film was found to be strongly dependent on carrier concentration, and was described by Kane's k.p model, with non-parabolic dispersion relation for carrier in the conduction band. The position of the Fermi-level in InN films was modulated by the carrier concentration in the InN films. The barrier height of the heterojunctions as estimated from I–V characteristic was also found to be dependent on the carrier concentration of InN.     

A simple and efficient route to the FKBP-binding domain from rapamycin

A simple and highly efficient route to the FKBP-binding domain (FKBD) from the natural product rapamycin has been developed, which entails a sequence of ozonolysis/Baeyer-Villiger/Wittig reactions. The newly synthesized FKBD may serve as a core to assemble hybrid macrocyclic libraries for the discovery of novel probes of protein function and to synthesize new ligands for the FKBP family of proteins.     

Unusual aspects of ion‐pairing effects in room temperature ionic liquids

Herein, we report our observations on voltammetric investigations about the redox behaviour of para‐nitrotoluene, 1,4‐benzoquinone and ferrocene, aimed at exploring the unusual aspects of ion‐pairing phenomena in imidazolium‐based room temperature ionic liquids (RTILs). Our observations indicate that the stabilization of electrogenerated ion/radical ion intermediates depends upon the potential of the working electrode and the overall composition of RTILs. In light of observed relative trends and quantum mechanical calculations, we propose that the ion‐pair stabilization of electrogenerated charged species in RTILs is closely related to the structural organization and composition of electrode/RTIL interface. Copyright © 2012 John Wiley & Sons, Ltd.