Infrared spectroscopy studies of cation effects on lipopolysaccharides in aqueous solution

The conformation of amphiphilic lipopolysaccharides (LPS) influences the behavior of free and cell-bound LPS in aqueous environments, including their adhesion to surfaces. Conformational changes in Pseudomonas aeruginosa serotype 10 LPS aggregates resulting from changes in solution pH (3, 6, and 9), ionic strength [I] 1, 10, and 100 mmol L⁻¹, and electrolyte composition (NaCl and CaCl₂) were investigated via attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy. ATR-FTIR data indicate that LPS forms more stable aggregates in NaCl relative to CaCl₂ solutions. Time- and cation-dependent changes in ATR-FTIR data suggest that LPS aggregates are perturbed by Ca²⁺ complexation at lipid A phosphoryl groups, which leads to reorientation of the lipid A at the surface of a ZnSe ATR internal reflection element (IRE). Polarized ATR-FTIR investigations reveal orientation of LPS dipoles approximately perpendicular to the IRE plane for both Na- and Ca-LPS. The results indicate that changes in solution chemistry strongly impact the conformation, intermolecular and interfacial behavior of LPS in aqueous systems.     

<Emphasis Type="Italic">Arcopilus aureus</Emphasis>, a Resveratrol-Producing Endophyte from <Emphasis Type="Italic">Vitis vinifera</Emphasis>

Due to great interest on producing bioactive compounds for functional foods and biopharmaceuticals, it is important to explore the microbial degradation of potential sources of target biomolecules. Gallotannins are polyphenols present in nature, an example of them is tannic acid which is susceptible to enzymatic hydrolysis. This hydrolysis is performed by tannase or tannin acyl hydrolase, releasing in this way, biomolecules with high-added value. In the present study, chemical profiles obtained after fungal degradation of tannic acid under two bioprocesses (submerged fermentation (SmF) and solid state fermentation (SSF)) were determined. In both fermentation systems (SmF and SSF), Aspergillus niger GH1 strain and tannic acid as a sole carbon source and inducer were used (the presence of tannic acid promotes production of enzyme tannase). In case of SSF, polyurethane foam (PUF) was used like as support of fermentation; culture medium only was used in case of submerged fermentation. Fermentation processes were monitored during 72 h; samples were taken kinetically every 8 h; and all extracts obtained were partially purified to obtain polyphenolic fraction and then were analyzed by liquid chromatography-mass spectrometry (LC-MS). Molecules like gallic acid and n-galloyl glucose were identified as intermediates in degradation of tannic acid; during SSF was identified ellagic acid production. The results obtained in this study will contribute to biotechnological production of ellagic acid.     

Dihydrooxazolones and dihydroimidazolones derived from acylglycines: syntheses,molecular structures and supramolecular assembly

Syntheses and structures are described for some alkylidene‐substituted dihydrooxazolones and dihydroimidazoles derived from simple acylglycines. A second, triclinic, polymorph of 4‐benzylidene‐2‐(4‐methylphenyl)‐1,3‐oxazol‐5(4H)‐one, C₁₇H₁₃NO₂, (I), has been identified and the structure of 2‐methyl‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one, C₉H₇NO₂S, (II), has been rerefined taking into account the orientational disorder of the thienyl group in each of the two independent molecules. The reactions of phenylhydrazine with 2‐phenyl‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one or 2‐(4‐methylphenyl)‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one yield, respectively, 3‐anilino‐2‐phenyl‐5‐[(thiophen‐2‐yl)methylidene]‐3,5‐dihydro‐4H‐imidazol‐4‐one, C₁₀H₁₅N₃OS, (III), and 3‐anilino‐2‐(4‐methylphenyl)‐5‐[(thiophen‐2‐yl)methylidene]‐3,5‐dihydro‐4H‐imidazol‐4‐one, C₂₁H₁₇N₃OS, (IV), which both exhibit orientational disorder in their thienyl groups. The reactions of 2‐phenyl‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one with hydrazine hydrate or with water yield, respectively, N‐[3‐hydrazinyl‐3‐oxo‐1‐(thiophen‐2‐yl)prop‐1‐en‐2‐yl]benzamide and 2‐(benzoylamino)‐3‐(thiophen‐2‐yl)prop‐2‐enoic acid, which in turn react, respectively, with thiophene‐2‐carbaldehyde to form 2‐phenyl‐5‐[(thiophen‐2‐yl)methylidene]‐3‐{[(E)‐(thiophen‐2‐yl)methylidene]amino}‐3,5‐dihydro‐4H‐imidazol‐4‐one, C₁₉H₁₃N₃OS₂, (V), which exhibits orientational disorder in only one of its thienyl groups, and with methanol to give methyl (2Z)‐2‐(benzoylamino)‐3‐(thiophen‐2‐yl)prop‐2‐enoate, C₁₅H₁₃NO₃S, (VI). There are no direction‐specific intermolecular interactions in the crystal structure of the triclinic polymorph of (I), but the molecules of (II) are linked by two independent C—H...O hydrogen bonds to form C₂²(14) chains. Compounds (III) and (IV) both form centrosymmetric R₂²(10) dimers built from N—H...O hydrogen bonds, while compound (V) forms a centrosymmetric R₂²(10) dimer built from C—H...O hydrogen bonds. In the structure of compound (VI), a combination of N—H...O and C—H...π(arene) hydrogen bonds links the molecules into sheets. Comparisons are made with some similar compounds.     

Potential Xanthine Oxidase Inhibitory Activity of Endophytic Lasiodiplodia pseudotheobromae

Xanthine oxidase is considered as a potential target for treatment of hyperuricemia. Hyperuricemia is predisposing factor for gout, chronic heart failure, atherosclerosis, tissue injury, and ischemia. To date, only two inhibitors of xanthine oxidase viz. allopurinol and febuxostat have been clinically approved for used as drugs. In the process of searching for new xanthine oxidase inhibitors, we screened culture filtrates of 42 endophytic fungi using in vitro qualitative and quantitative XO inhibitory assays. The qualitative assay exhibited potential XO inhibition by culture filtrates of four isolates viz. #1048 AMSTITYEL, #2CCSTITD, #6AMLWLS, and #96 CMSTITNEY. The XO inhibitory activity was present only in the chloroform extract of the culture filtrates. Chloroform extract of culture filtrate #1048 AMSTITYEL exhibited the highest inhibition of XO with an IC₅₀ value of 0.61 μg ml^?1 which was better than allopurinol exhibiting an IC₅₀ of 0.937 μg ml^?1 while febuxostat exhibited a much lower IC₅₀ of 0.076 μg ml^?1. Further, molecular phylogenetic tools and morphological studies were used to identify #1048 AMSTITYEL as Lasiodiplodia pseudotheobromae. This is the first report of an endophytic Lasiodiplodia pseudotheobromae from Aegle marmelos exhibiting potential XO Inhibitory activity.     

Visual snapshots of intracellular kinase activity at the onset of mitosis

Visual snapshots of intracellular kinase activity can be acquired with exquisite temporal control by using a light-activatable (caged) sensor, thereby providing a means to interrogate enzymatic activity at any point during the cell-division cycle. Robust protein kinase activity transpires just prior to, but not immediately after, nuclear envelope breakdown (NEB). Furthermore, kinase activity is required for the progression from prophase into metaphase. Finally, the application of selective protein kinase C (PKC) inhibitors, in combination with the caged sensor, correlates the action of the PKC beta isoform with subsequent NEB.     

Nek2 Kinase Signaling in Malaria,Bone, Immune and Kidney Disorders to Metastatic Cancers and Drug Resistance: Progress on Nek2 Inhibitor Development

Cell cycle kinases represent an important component of the cell machinery that controls signal transduction involved in cell proliferation, growth, and differentiation. Nek2 is a mitotic Ser/Thr kinase that localizes predominantly to centrosomes and kinetochores and orchestrates centrosome disjunction and faithful chromosomal segregation. Its activity is tightly regulated during the cell cycle with the help of other kinases and phosphatases and via proteasomal degradation. Increased levels of Nek2 kinase can promote centrosome amplification (CA), mitotic defects, chromosome instability (CIN), tumor growth, and cancer metastasis. While it remains a highly attractive target for the development of anti-cancer therapeutics, several new roles of the Nek2 enzyme have recently emerged: these include drug resistance, bone, ciliopathies, immune and kidney diseases, and parasitic diseases such as malaria. Therefore, Nek2 is at the interface of multiple cellular processes and can influence numerous cellular signaling networks. Herein, we provide a critical overview of Nek2 kinase biology and discuss the signaling roles it plays in both normal and diseased human physiology. While the majority of research efforts over the last two decades have focused on the roles of Nek2 kinase in tumor development and cancer metastasis, the signaling mechanisms involving the key players associated with several other notable human diseases are highlighted here. We summarize the efforts made so far to develop Nek2 inhibitory small molecules, illustrate their action modalities, and provide our opinion on the future of Nek2-targeted therapeutics. It is anticipated that the functional inhibition of Nek2 kinase will be a key strategy going forward in drug development, with applications across multiple human diseases.     

Factors affecting glycerol production byPichia farinosa under alkaline conditions

Glycerol is an important and valuable chemical that can be produced from renewable resources by fermentation. The desirable features of a successful process are high values of substrate conversions and high yields and concentrations of glycerol in the product broth, coupled with rapid fermentation cycles. Of the various osmophilic and nonosmophilic yeasts tested for their ability to produce glycerol in the presence and absence of steering agents (sodium sulfite or sodium carbonate), an osmophilic yeastPichia farinosa (ATCC 20210) was found to give attractive yields. Important variables influencing glycerol production by this strain under alkaline conditions using sodium carbonate have been investigated. A rapid fermentation (less than 120 h), coupled with high glycerol yields (45%), has been obtained.     

A highly selective chemosensor derived from benzamide hydrazones for the detection of cyanide ion in organic and organic-aqueous media: design,synthesis, sensing and computational studies

ABSTRACT

A new, highly sensitive and selective chemosensing method has been developed for the detection of cyanide ion using benzamide hydrazone receptors (R1-R4). The sensing ability of these compounds towards CN^? in the presence of Br ^?, HSO₄ ^?, Cl^?, OH^?, I^?, F^?, AcO^?, NO₂ ^? and NO₃ ^? in DMF and DMF-Aqueous mixture (DMF:H₂O, 9:1 v/v) was investigated. The binding characteristics of the probe with cyanide ions carried out by ¹ H NMR titrations indicated the deprotonation of N-H group through H-bond interactions between benzamide hydrazones and cyanide ions; it has been theoretically supported by DFT. The binding constant (Ka) and stoichiometry of the host–guest complex formed was calculated by the Benesi–Hildebrand (B–H) plot, and strong interaction of the probe with CN^- ions forming a 1:2 binding stoichiometry has been noted in this study. In a DMF and aqueous medium for CN^? ion, the lower limit of detection (LOD in ppm) is compared to the limit of quantification (LOQ in ppm), which is quite better in terms of sensitivity.     

Production,Purification and Characterisation of a Potential Fibrinolytic Protease from Endophytic <Emphasis Type="Italic">Xylaria curta</Emphasis> by Solid Substrate Fermentation

The present investigation highlights the optimal conditions for production of a non-toxic, bi-functional fibrinolytic enzyme xylarinase produced by endophytic fungus Xylaria curta by solid substrate fermentation using rice chaff medium. The purified enzyme is a monomeric protein with a molecular mass of ～33 kDa. The enzyme exhibits cleavage of Aα and Bβ chains of fibrin(ogen) and has no effect on γ chain. The optimal fibrinolytic activity of the enzyme was observed at 35 °C and pH 8. The fibrinolytic activity was enhanced in the presence of Ca²⁺, whereas it was completely inhibited in the presence of Fe²⁺ and Zn²⁺ ions and inhibitors like EDTA and EGTA suggesting it to be a metalloprotease. The K _m and V _max of the enzyme for azocasein were 326 μM and 0.13 μM min^?1. The N-terminal sequence of the enzyme (SNGPLPGGVVWAG) was same when compared to xylarinase isolated from culture broth of X. curta. Thus, xylarinase could be exploited as a potent clot busting enzyme which could be produced on large scale using solid substrate fermentation.