Cobalt(II) complexes of 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones

Cobalt(II) complexes of five 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by i.r., electronic and n.m.r. spectra, and by magnetic susceptibilities and molar conductivity measurements. The thiosemicarbazones coordinate as monoanionic or neutral ligands via the thiosemicarbazone azomethine nitrogen and thione/thiolato sulfur, the latter by loss of the thioamide hydrogen, N(2)H. The resulting cobalt(II) complexes exhibit a varied stereochemistry.     

Nickel(II) complexes of 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones

Nickel(II) complexes with five 4-acetamidobenzaldehyde N(4)- substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. N.m.r., i.r. and electronic spectra of the thiosemicarbazones and their complexes, along with physical properties of the complexes, have been recorded. These thiosemicarbazones coordinate as anionic ligands via the thiosemicarbazone moiety's azomethine nitrogen and thiolate sulfur [upon loss of the N(2) hydrogen] when reacted with NiCl2 in the presence of Et3N or with Ni(OAc)2.     

Structural and Spectral Study of Copper(II) Complexes of Pyridil bis{3‐piperidyl‐, bis{hexamethyleneiminyl‐, bis{N(4)‐diethyl‐, and bis{N(4)‐dipropylthiosemicarbazones}

Pyridil bis(N(4)‐substituted thiosemicarbazones) have been prepared in which the substituents in place of the NH₂ group in the thiosemicarbazone moieties are piperidinyl (H₂Plpip), hexamethyleneiminyl (H₂Plhexim), diethylaminyl (H₂Pl4DE), and dipropylaminyl (H₂Pl4DP). IR, electronic, mass, and ESR spectra of their copper(II) complexes are reported. Crystal structure determinations of H₂Pl4DE and three of the copper(II) complexes of formula [Cu(Plpip)], [Cu(Plhexim)] and [Cu(Pl4DE)]₂ · 2[Cu(Pl4DE)], are included. H₂Pl4DE lacks hydrogen bonding between the thiosemicarbazone moieties, but each moiety is in the Z configuration form with hydrogen bonding from the thiosemicarbazone moieties to the pyridyl nitrogen atoms. The crystal used for the structure determination of [Cu(Plhexim)] was isolated from an electrochemical preparation. In all the new compounds the deprotonated ligands are N,N,S,S‐tetradentate, coordinating to the copper(II) centre through their azomethine nitrogen atoms and their thiocarbonyl sulfur atoms.     

Two Novel Plumeran Indole Alkaloids Isolated from Aspidosperma cylindrocarpon (Apocynaceae)

Two novel indole alkaloids with plumeran skeleton, N‐benzoyl‐12‐demethoxycylindrocarine and N‐cinnamoyl‐12‐demethoxycylindrocarine ( 1 and 2 , resp.), were isolated from the MeOH extract of the stem bark of Aspidosperma cylindrocarpon Müll .Arg . These compounds were obtained by high‐speed counter‐current chromatography, and their structures were elucidated on the basis of their NMR (1D and 2D) data. They were tested in vitro against chloroquine‐resistant strains of Plasmodium falciparum, and only 2 showed a weak activity (IC₅₀ 127.97 ng/ml with respect to the standard drug). Several other known compounds, comprising steroids, flavonoids, the rarely found atraric acid, as well as the previously reported alkaloid 3 , were also isolated by conventional chromatographic techniques.     

Interaction of peptides obtained from the enzymatic hydrolysis of soybean meal with cyclodextrins: an evaluation of bitterness reduction

Enzymatic hydrolysis improves the functional and nutritional characteristics of soybean meal proteins. However, the presence of hydrophobic peptides can cause an intense bitterness to the hydrolysate, which is deleterious in terms of final product taste. In this paper we evaluate the interaction of peptides employed for the enzymatic hydrolysis of soybean meal with α-, β- and γ-cyclodextrins, aiming to reduce the bitter taste. Each cyclodextrin was added in mass fractions of 1.5, 2.0 and 2.5% in a hydrolysate of soybean meal prepared with enzyme Alcalase^® 2.4 L at 1% concentration (protein/protein). In order to identify possible interactions between the components, several instrumental techniques were employed. NMR H¹ spectra evidenced strong interactivities between the peptides’ aromatic and aliphatic regions and the cyclodextrins’ internal cavities. Analysis by an electronic tongue system showed that the addition of α- and β-cyclodextrins to the hydrolysate, at concentrations 1.5 and 2.0% (w/w), respectively, induced the greatest difference with regard to control hydrolysate. The difference was also sensory perceptible to untrained tasters in a bitterness ranking test, and reveal that the treatment was efficient in reducing bitterness compared to the control samples, indicating this method as a suitable approach for masking bitterness in soybean hydrolysates.     

Light‐mediated DNA Repair Prevents UVB‐induced Cell Cycle Arrest in Embryos of the Crustacean Macrobrachium olfersi

High levels of ultraviolet‐B (UVB) radiation can negatively affect aquatic animals. Macrobrachium olfersi is a prawn that lives in clear freshwaters and during the breeding season, females carry eggs in an external brood pouch. Therefore, we hypothesize that eggs are also exposed to environmental UVB radiation. The aim of this study was to investigate whether UVB radiation induces DNA damage and compromises cell cycle in embryos of M. olfersi. In laboratory, UVB irradiance (310 mW. cm^?2) that embryos receive in the natural environment was simulated. After irradiation, embryos were kept under different light conditions in order to recognize the presence of cell repair. UVB radiation induces DNA damage, specifically thymine dimers. After 48 h of UVB exposure, a significant decrease in the level of these dimers was observed in embryos kept under visible light while it remained constant in the dark. Moreover, under visible light and darkness, a decrease in proliferation was observed after 48 h of irradiation. An increase in PCNA expression and decrease in p53 expression were observed after, respectively, 1 and 48 h of exposure. Our results showed that UVB radiation disturbs the cell cycle and induces DNA damage in M. olfersi embryos. However, under visible light these embryos showed successful DNA repair.     

Electron scattering from trans 1,3-butadiene molecule: cross-sections, oscillator strength and VUV photoabsorption cross-sections

Electron energy-loss spectra for the butadiene molecule were measured in the scattering angular range of 2.0° to 8.0°, in an energy-loss range from 2 to 50 eV, using 1000 eV incident electrons. The absolute generalized oscillator strength (GOS) and inelastic cross section have been determined for the \hbox{$\tilde{\rm X}^{1}$}?X1A _g  → 1¹B _u transition. The absolute elastic differential cross section was also determined spanning an angular range from 2.0° to 40.0°. From a small angle electron energy-loss spectrum, the optical oscillator distribution (photoabsorption spectrum) for the butadiene molecule was obtained in the 2 to 100 eV photon energy range. Accurate ab initio calculations have been performed, within the First Born Approximation, for generalized oscillator strength (GOS) and excitation energies for the \hbox{$\tilde{\rm X}^{1}$}?X1A _g  → 1¹B _u and \hbox{$\tilde{\rm X}^{1}$}?X1A _g  → 2¹A _g transitions. Our results emphasize the importance of using highly correlated wavefunctions and accurate methodologies in the calculation of the GOS for electron impact-induced electronic transitions in molecules.     

Inclusion of Benzaldehyde Semicarbazone into β-Cyclodextrin Produces a Very Effective Anticonvulsant Formulation

Aryl semicarbazones can be considered a novel class of compounds presenting anticonvulsant activity. In order to improve the efficiency and bioavailability of benzaldehyde semicarbazone (BS) we used the host–guest strategy and β-cyclodextrin (β-CD) to prepare a BS/β-CD 1:1 inclusion compound, which was characterized by thermal analyses (TG, DTG, DSC), XRD powder pattern diffraction analyses, infrared data and ¹H, ¹³C, 2D-ROESY NMR and ¹H relaxation times. The BS/β-CD inclusion compound was tested in rats using the maximum electroshock (MES) screen. The minimum dose necessary to produce anticonvulsant activity decreased from 100 mg/Kg (ip or vo) for the free semicarbazone to 25 mg/Kg/vo (75%) and 15 mg/Kg/ip (85%), indicating that the host–guest strategy that uses β-CD and BS is very effective and could be successfully employed in the preparation of pharmaceutical formulationof anticonvulsants.     

Ruthenium(II) complexes containing 2-pyridineformamide- and 2-benzoylpyridine-derived thiosemicarbazones and PPh3: NMR and electrochemical studies of cis-trans-isomerization

[RuCl(L)(PPh(3))(2)] complexes with 2-benzoylpyridine- and 2-pyridineformamide-derived thiosemicarbazones (HL) were obtained and fully characterized. The complexes form cis-trans isomers. The cis isomer is disfavored by the sterical effect of two bulky groups close to each other whereas the trans isomer is disfavored by the electronic effect of competition of two phosphorous for pi-bonding d orbitals of the metal. Our results suggest that, although both factors may be operating simultaneously, in CH(2)Cl(2) solution the balance of these counterpoising effects favors the formation of the trans isomer.     

Synthesis and characterization of CeO<Subscript>2</Subscript>–graphene composite

The synthesis and characterization of graphite oxide (GO), graphene (GS), and the composites: GS–CeO₂ and GO–CeO₂ are reported. This synthesis was carried out by mixing aqueous solutions of CeCl₃·7H₂O and GO, which yields the oxidized composite GO–CeO₂. GO–CeO₂ was hydrothermally reduced with ethylene glycol, at 120 °C, yielding the reduced composite GS–CeO₂. GO, GS ,and the composites with CeO₂ were characterized by CHN, TG/DTG, BET, XRD, SEM microscopy, FTIR, and Raman spectroscopy. The estimation of crystallite size of CeO₂ anchored on GO and on GS by Raman, XRD, and SEM agreed very well showing diameters about 5 nm. The role of particles of CeO₂ coating carbon sheets of GO and GS was discussed.