Phytochemical composition,in vitro antioxidant activity and antibacterial mechanisms of Neolamarckia cadamba fruits extracts

Aqueous extracts of Neolamarckia cadamba fruits prepared at different maturity stages were used for the analysis of various phytochemicals, and their antioxidant and antibacterial activities were determined. Ripe fruit extract had highest phenolics (3.14 mM GAE/ g fruit extract) with caffeic acid, tannic acid, syringic acid and quercetin as major phenolic compounds. The ripe fruit extract showed lowest IC₅₀ values in DPPH radical scavenging assay (231.33 μg fruit extract/ mL), and highest ABTS radical scavenging activity (111.18 μM TEAC/g). Immature fruit extract showed lowest minimum inhibitory concentration against tested bacteria, and the antibacterial activity was probably due to membrane permeation, as was evident by leakage of genetic material and reduction in propidium iodide uptake by bacterium; and by inhibition of sugar and amino acid uptake. The appreciable amount of phenolic compounds and biological activities in the aqueous extracts of N. cadamba fruits suggests it's potential application as natural preservative.     

Serum biomarker profiling by solid-phase extraction with particle-embedded micro tips and matrix-assisted laser desorption/ionization mass spectrometry

One of the main challenges in high-throughput serum profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is the development of proteome fractionation approaches that allow the acquisition of reproducible profiles with a maximum number of spectral features and minimum interferences from biological matrices. This study evaluates a new class of solid-phase extraction (SPE) pipette tips embedded with different chromatographic media for fractionation of model protein digests and serum samples. The materials embedded include strong anion exchange (SAX), weak cation exchange (WCX), C18, C8, C4, immobilized metal affinity chromatography (IMAC) and zirconium dioxide particles. Simple and rapid serum proteome profiling protocols based on these SPE micro tips are described and tested using a variety of MALDI matrices. We show that different types of particle-embedded SPE micro tips provide complementary information in terms of the spectral features detected for beta-casein digests and control human serum samples. The effect of different sample pretreatments, such as serum dilution and ultrafiltration using molecular weight cut-off membranes, and the reproducibility observed for replicate experiments, are also evaluated. The results demonstrate the usefulness of these simple SPE tips combined with offline MALDI-TOF MS for obtaining information-rich serum profiles, resulting in a robust, versatile and reproducible open-source platform for serum biomarker discovery.     

PAM-microfabricated polyurethane scaffolds: in vivo and in vitro preliminary studies

Polymeric scaffolds were realised with linear degradable PU in the form of square, hexagonal and octagonal grids. They were characterised in terms of their mechanical properties. Analysis shows that the mechanical properties of the scaffolds depend on their geometries which are easily modulated using PAM. In vitro biological assays showed that PU promotes the adhesion and proliferation of fibroblast cells and that cell activities are better on PU scaffolds than on PU films. In vivo implantation of PU and PLGA scaffolds and PU films demonstrated that the scaffolds are completely resorbed after three months with a slight inflammatory response, while the PU film was still present after six months with an intense granulomatous reaction.     

Laboratory evidence for stochastic plasma-wave growth

The first laboratory confirmation of stochastic growth theory is reported. Floating potential fluctuations are measured in a vacuum arc centrifuge using a Langmuir probe. Statistical analysis of the energy density reveals a lognormal distribution over roughly 2 orders of magnitude, with a high-field nonlinear cutoff whose spatial dependence is consistent with the predicted eigenmode profile. These results are consistent with stochastic growth and nonlinear saturation of a spatially extended eigenmode, the first evidence for stochastic growth of an extended structure.     

Chemoselective and Stereoselective Debromination of Vicinal-Dibromides with Sodium Dithionite

A simple and effcient procedure for the quantitative debromination of vic-dibromides has been reported with sodium dithionite at ambient temperature. These eliminations are chemoselective and also stereoselective.     

Bis[(L)prolinato‐N,O]Zn in acetic acid–water: a novel catalytic system for the synthesis of β‐amino carbonyls via Mannich reaction at room temperature

Zn[(L)proline]₂ was used as an efficient catalyst for the one‐pot multicomponent reactions (MCR) of different aromatic amines, aromatic aldehyde and ketones in aqueous media. This method provides a novel and improved method for obtaining stereoselective β‐amino carbonyl compounds in terms of good yield. Little catalyst loading, recyclability, easy accessibility of the catalyst and aqueous media are the main features of this protocol. Moreover column chromatography and recrystallization of product are not required as the crude product itself is very pure. Powder XRD and TEM images of the catalyst were taken for the first time. Copyright © 2011 John Wiley & Sons, Ltd.     

Structural study on the organoantimony(III) NCN - Chelated compounds [2,6-(Me2NCH2)2C6H3]SbX2 - Influence of the polar group X

The reactions of organoantimony chloride LSbCl₂ (1) (L = [2,6-(Me₂NCH₂)₂C₆H₃]⁻) with the silver salts of selected carboxylic acids (1:2 molar ratio) resulted to the corresponding organoantimony carboxylates LSbX₂, where X = CH₃COO for (2); CF₃COO for (3). Similar reactions of 1 with the silver salt of the low nucleophilic anion (1:0.5 and 1:1 molar ratio) gave the ionic compounds [LSb(Cl)--Cl-Sb(Cl)L]⁺[CB₁₁H₁₂]⁻ (4), and [LSbCl]⁺[CB₁₁H₁₂]⁻ (5). All compounds were characterized by the help of the elemental analysis, ESI-MS, ¹H, ¹¹B, ¹³C NMR spectroscopy and IR spectroscopy. The solid state structure investigation using single crystal X-ray diffraction technique (3-5) revealed the presence of the strong Sb-N intramolecular dative connections in all cases and also significant differences in the shapes of the coordination polyhedra around the central antimony atoms was observed, i.e. a tetragonal pyramidal environment in 3 (CF₃COO groups are placed mutually in trans positions), an unusual chlorine bridged dinuclear cation consisting of one apex (Cl atom) sharing square pyramids in 4, and finally a vacant ψ-trigonal bipyramid around the central antimony atom in 5. Even more, crystallization of 5 from THF provided the single crystals of a THF aduct of 5 [LSbCl(THF)]⁺[CB₁₁H₁₂]⁻5a, where the central antimony atom is located in a tetragonal pyramidal environment. The solid state structures of 3-5 are retained in solution. Solution structure of the compound 2 was determined by the help of VT-¹H NMR spectroscopy and IR spectroscopy showing, that both carboxylates (CH₃COO) are unidentate and are placed mutually in cis positions in the coordination polyhedron around the central antimony atom. The whole coordination polyhedron in 2 might be best described as a biccaped - trigonal pyramid, due to the additional Sb-N intramolecular interactions.     

Comparative study of thermal degradation behavior of graft copolymers of polysaccharides and vinyl monomers

The thermal degradation of graft copolymers of both polysaccharides (guar gum and xanthan gum) showed gradual decrease in mass loss. Pure guar gum degraded about 95% but pure xanthan gum degraded about 76% up to 1173.15 K, while graft copolymers of guar gum and xanthan gum degraded only 65–76% up to 1173.15 K. Acrylic acid grafted guar gum and xanthan gum showing two-step degradation with formation of anhydride and ketonic linkage during heating, same pattern of degradation was found for xanthan gum-g-methacrylic acid. Guar gum-g-acrylamide degraded in single step and xanthan gum-g-acrylamide started to degrade above 448.15 K and it is a two-stage process and imparts thermal stability due to the formation of imide linkage with evolution NH₃. Guar gum-g-methacrylamide degraded in three steps due to the loss of NH₃ and CO₂ successively. 4-vinyl pyridine grafted both polysaccharides show single step degradation due to loss of pyridine pendent. N-vinyl formamide grafted guar gum and xanthan gum started to degrade at about 427.15 K, showed two-stage degradation process with the evolution of CO and NH₃ molecules while guar gum-g-(N-vinyl-2-pyrrolidone) degraded into two steps by the loss of pyrrolidone nucleus. Gum-g-2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) showed two-step degradation processes in two successive degradation steps, while xanthan gum-g-AMPS has started degradation at about 427.15 K and completed in five degradation steps. Overall, it was found that the grafted polysaccharides are thermally more stable than pure polysaccharides.     

Diversity-oriented approach to biologically relevant molecular frameworks starting with beta-naphthol and using the Claisen rearrangement and olefin metathesis as key steps

A diversity-oriented approach for the synthesis of various structurally different molecular frameworks from readily accessible and common precursors is described. A Claisen rearrangement followed by ring-closing metathesis or ethylene-promoted ring-closing enyne metathesis has been utilized as the key synthetic transformation to generate naphthoxepine derivatives. The ring-closing metathesis approach has also been used to generate spirocyclic compounds and the pleiadene framework.     

Electron transfer in amino acid.nucleic acid base complexes: EPR, ENDOR, and DFT study of X-irradiated N-formylglycine.cytosine complex crystals

Single crystals of the 1:1 complex of the nucleic acid base cytosine and the dipeptide N-formylglycine (C.NFG) have been irradiated at 10 and 273 K to doses of about 70 kGy and studied at temperatures between 10 and 293 K using 24 GHz (K-band) and 9.5 GHz (X-band) electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), and ENDOR-induced EPR (EIE) spectroscopy. In this complex, the cytosine base is hydrogen bonded at positions N3 and N4 to the carboxylic group of the dipeptide, and the N3 position of cytosine has become protonated by the carboxylic group. At 10 K, two major radicals were characterized and identified. One of these (R1) is ascribed to the decarboxylated N-formylglycine one-electron oxidized species. The other (R2) is the N3-protonated cytosine one-electron reduced species. A third minority species (R3) appears to be a different conformation or protonation state of the one-electron reduced cytosine radical. Upon warming, the R2 and R3 radicals decay at about 100 K, and at 295 K, the only cytosine-centered radicals present are the C5 and C6 H-addition radicals (R5, R6). The R1 radical decays at about 150 K, and a glycine backbone radical (R4) grows in slowly. Thus, in the complex, a complete separation of initial oxidation and reduction events occurs, with oxidation localized at the dipeptide moiety, whereas reduction occurs at the nucleic acid base moiety. DFT calculations indicate that this separation is driven by large differences in electron affinities and ionization potentials between the two constituents of the complex. Once the initial oxidation and reduction products are trapped, no further electron transfer between the two constituents of the complex takes place.