bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Convenient One-Pot Synthesis of Pyrazolo[3,4-d]pyrimidines and s-Triazolo[3,4-b][1,3,5]thiadiazines
Authors: Hozien Zeinab A. , Sarhan Abd El-Wareth A. O. , El-Sherief Hassan A. H. , Mahmoud Abdalla M. 
Published: February 2015

Abstract
The reaction of 5-amino-3-aryl-1-phenylpyrazoles (1a-d) with formaldehyde and secondary amines in boiling ethanol gave the corresponding 4-alkylaminomethyl derivatives (2a-f) and bis-(4-pyrazolyl)methane (4a,b) as byproduct. Such reaction with primary aliphatic and aro­ matic amines at room temperature afforded 1,3,5-trisubstituted (5a-h) and 1,3.5,7-tetrasubstituted tetrahydropyrazolo[3,4-d]pyrimidines (8a-k) respectively in good yield. Similarily, the Mannich reaction of 5-mercapto-3-phenyl-1,2,4-triazole (9) with secondary amines, in boiling ethanol, and primary aromatic amines, at room temperature, gave 2 -substituted aminomethyl derivatives (10a-c) and (14a-g) respectively,while with primary aliphatic amines, p-toluidine and p-anisidine,at room temperature,and with other primary aromatic amines, in boiling ethanol, afforded the cyclized products 12,4-triazolo[3,4-b]thiadiazines (13a-e); (15f,g) and (15a-e), respectively.
Die Kristallstruckturen der Phosphaniminato-Komplexe.[Ti3
IVCl8(NPMe3)3]Cl und [V2
III/IVCl4(NPPh3)3]/Crystal Structures of the Phosphoraneiminato Complexes [Ti3
IVCl8(NPMe3)3]Cl and [V2
III/IVCl4(NPPh3)3]
Authors: Miekisch Thomas , Harms Klaus , Wocadlo Sigrid , Massa Werner , Neumüller Bernhard , Frommen Christoph , Dehnicke Kurt 
Published: February 2015

Abstract
[Ti3Cl8(NPMe3)3]Cl has been prepared by the reaction of TiCl3(THF)3 with Me3SiNPMe3 in dichloromethane forming green moisture sensitive crystals. According to the crystal structure determination the titanium atoms of the cation [Ti3Cl8(NPMe3)3]+ are linked by two μ3-N atoms of two NPMe3
- groups forming a distorted trigonal-bipyramidal arrangement. The third NPMe3
- group and two of the chlorine atoms have μ2-bridging functions. The mixed-valence complex [V2Cl4(NPPh3)3] is formed as dark green moisture sensitive crystals by the reaction of vanadium trichloride with Me3SiNPPh3 in boiling toluene. According to the crystal structure determination the vanadium atoms are linked by two μ2-N atoms of two NPPh3
- groups forming a nonplanar V2N2 four-membered ring with a V-V distance of 266.8(1) pm which corresponds to a (σ, 1/2π) bond type. This is confirmed by the measurement of the magnetic susceptibility which leads to a magnetic moment of 1.45(5) B. M., corresponding to the remaining d1 -electron.
Zur Chemie der 1,3,5-Triaza-2-phosphorin-4,6-dione, Teil XIII. Darstellung und Röntgenstrukturanalyse des 1,3,5-Trimethyl-2-trichlormethyl-Derivats. Reaktionen einiger 1,3,5-Trimethyl-1,3,5-triaza-2-(R)-phosphorin-4,6-dione/Chemistry of the l,3,5-Triaza-2-phosphorine-4.6-diones, Part XIII. Synthesis and X -Ray Crystal Structure Determination of the 1,3,5-Trimethyl-2- trichlorom ethyl Derivative. Reactions of Some 1,3,5-Trimethyl-1,3,5-triaza-2-(R )-phosphorine-4,6-diones
Authors: Pinchuk Vasily A. , Neda Ion , Kaukorat Thomas , Farkens Michael , Fischer Axel K. , Jones Peter G. , Schmutzler Reinhard 
Published: February 2015

Abstract
Upon heating 1,3,5-trimethylbiuret (1) with trichloromethyldichlorophosphine in the presence of triethylamine, 2-trichloromethyl-1,3,5-trimethyl-1,3,5-triaza-2σ3λ3-phosphorine-4,6-dione (2) was obtained in good yield. Aside from NMR spectroscopic characterization, compound 2 was investigated by X-ray crystal structure analysis, representing the first case of the solid state characterization of a 2-trihalomethyl-1,3,5-trimethyl-1,3,5-triaza-2σ3λ3-phosphorine-4,6-dione derivative. The heterocycle presents an envelope conformation with phosphorus out of the plane of the other atoms. Reaction of the monochloromethyl derivative (3) corresponding to 2, with a sterically demanding azide led by oxidation of phosphorus to the stable σ4λ5-P derivative (4). 2-Hydro-1,3,5-trimethyl-1,3,5-triaza-2-oxo-2σ4λ5-phosphorine-4,6-dione (5) reacted with p-nitrobenzylidene benzylimine with formation of 6 by insertion of the C=N double bond of the imine into the P-H bond. Intramolecular hydrogen bonding in 6 was observed by 1H NMR and IR spectroscopy. Reaction of 2-(methylamino)-methyl-1,3,5-trimethyl-1,3,5-triaza-2-oxo-2σ4λ5-phosphorine-4,6-dione (7) with diethylamino-trimethylsilane led to the corresponding N-trimethylsilylated compound 8. Compound 9. bearing a peptoid group, was formed by reaction of 7 or 8 with 3-(chloroformyl)propionic acid methyl ester. The preferred method of synthesis of 9 is indicated.
Thermische Zersetzung und Lösungskalorimetrie von Ammoniumsamariumchloriden/Thermal Decomposition and Solution Calorimetry of Ammonium Samarium Chlorides
Authors: Hennig C. , Oppermann H. 
Published: February 2015

Abstract
We determined the decomposition equilibria of ammonium samarium chlorides (NH4)2SmCl5 and NH4Sm2Cl7 by total pressure measurements and derived their thermody­ namical data from the decomposition functions. The enthalpies of formation were compared with the results of the solution calorimetry. The heats of solution of all solid phases in the system SmCl3-NH4Cl and of Sm2O3 were measured in 4n HCl. The enthalpies of formation of ammonium samarium chlorides were derived from the enthalpies of formation of SmCl3 and of NH4Cl and their heats of solution.
Data by total pressure measurement
ΔH°B((NH4)2SmCl5,f,298) =-407,7 ± 2,9 kcal/mol;
S0((NH4)2SmCl5,f,298) = 84,0 ± 4,5 cal/K-mol;
ΔH°B((NH4)Sm2Cl7,f,298) = -576,8 ± 3,4 kcal/mol;
S°(NH4Sm2Cl7,f,298) = 98,1 ± 5,5 cal/K-mol.
Data by solution calorimetry
ΔH°B(SmCl3,f,298) = -248,1 ± 0,8 kcal/mol;
ΔH°B((NH4),SmCl5,f,298) = -404 ,3 ± 1,1 kcal/mol;
ΔH°B(NH4Sm9Cl7,f,298)= -572,3 ± 1,8 kcal/mol.
Synthesis of 6-Aryloxy- and 6-Arylalkoxy-2-chloropurines and Their Interactions with Purine Nucleoside Phosphorylase from Escherichia coli
Authors: Bzowska Agnieszka , Magnowska Lucyna , Kazimierczuk Zygmunt 
Published: February 2015

The phase transfer method was applied to perform the nucleophilic substitution of 2,6- dichloropurines by modified arylalkyl alcohol or phenols. Since under these conditions only the 6-halogen is exchanged, this method gives 2-chloro-6-aryloxy- and 2-chloro-6-arylalkoxypurines. 2-Chloro-6-benzylthiopurine was synthesized by alkylation of 2-chloro-6-thiopurine with benzyl bromide. The stereoisomers of 2-chloro-6-(1-phenyl-1-ethoxy)purine were obtained from R- and S-enantiomers of sec.-phenylethylalcohol and 2,6-dichloropurine.
All derivatives were tested for inhibition with purified hexameric E. coli purine nucleoside phosphorylase (PNP). For analogues showing IC50 < 10 μm, the type of inhibition and inhibition constants were determined. In all cases the experimental data were best described by the mixed-type inhibition model and the uncompetitive inhibition constant, Kiu, was found to be several-fold lower than the competitive inhibition constant, Kic. This effect seems to be due to the 6-aryloxy- or 6-arylalkoxy substituent, because a natural PNP substrate adenine, as well as 2-chloroadenine, show mixed type inhibition with almost the same inhibition constants Kiu and KiC.
The most potent inhibition was observed for 6-benzylthio-2-chloro-, 6-benzyloxy-2-chloro-, 2-chloro-6-(2-phenyl-l-ethoxy), 2-chloro-6-(3-phenyl-l-propoxy)- and 2-chloro-6-ethoxypurines (Kiu = 0.4, 0.6, 1.4, 1.4 and 2.2 μm, respectively). The R-stereoisomer of 2-chloro-6-(1pheny-1-ethoxy)purine has Kiu = 2.0 μm, whereas inhibition of its S counterpart is rather weak (IC50> 12 μm). More rigid (e.g. phenoxy-), non-planar (cyclohexyloxy-), or more bulky (2,4,6-trimethylphenoxy-) substituents at position 6 of the purine base gave less potent inhibitors (IC50 = 26, 56 and >100 μm, respectively). The derivatives are selective inhibitors of hexameric “high-molecular mass” PNPs because no inhibitory activity vs. trimeric Cellulomonas
sp. PNP was detected.
By establishing the ligand-dependent stabilization pattern of the E. coli PNP it was shown that the new derivatives, similarly as the natural purine bases, are able to form a dead-end ternary complex with the enzyme and orthophosphate. It was also shown that the derivatives are substrates in the reverse synthetic direction catalyzed by E. coli PNP
Oxygen Uptake during Photosynthesis of Isolated Pea Chloroplasts
Authors: Grotjohann Norbert , Messdaghi David , Kowallik Wolfgang 
Published: February 2015

Abstract
Mass spectrometric analysis of the gas exchange of illuminated leaflets of 10-14 d old pea seedlings revealed not only 16O2-liberation from photosynthetic H2
16O-splitting, but also uptake of 18O2, applied to the gas phase of the reaction vessel. Isolated intact chloroplasts of such leaflets suspended in a medium containing NaHCO3 and glycerate 3-phosphate, on irradiation with blue (λ 448 nm) or red (λ 679 nm) light also produced 16O2 from water oxidation and consumed 18O2 from the gas phase. The two reactions were saturated at the same quantum fluence rates. Uptake of 18oxygen was not affected by inhibitors of mito­chondrial respiration (alternative pathway included), such as rotenone (5 x l0-5 ᴍ), antimycin A (5 x l0-6 ᴍ), KCN (10-3 ᴍ), SHAM (10-3 ᴍ), or propylgallate (10-3 ᴍ). It was, however, absent, when photosynthetic 16oxygen evolution was completely inhibited by DCMU (10-5 ᴍ). DBMIB (10-5 ᴍ), assumed to prevent electron flow from plastoquinone pool to the cytochrome b6/f-complex, suppressed photosynthetic oxygen evolution, but did not impair uptake of 18O2. A similar result was obtained at application of 4 x l0-5 ᴍ antimycin A.
The data are interpreted to show a drain off to molecular oxygen of light-excited electrons from the photosynthetic electron transport chain at the site of plastoquinone pool during photosynthesis. This corresponds to chlororespiration, originally described for Chlamydomonas in darkness by Bennoun (1982). It is discussed, whether O2-uptake during photosynthesis is an additional means for providing ATP for photosynthetic CO2-reduction by increasing the proton gradient across the thylakoid membrane.
Grapevine Protoplasts as a Transient Expression System for Comparison of Stilbene Synthase Genes Containing cGMP-Responsive Promoter Elements
Authors: Brehm Ilka , Preisig-Müller Regina , Kindl Helmut 
Published: February 2015

Abstract
A method for preparing elicitor-responsive protoplasts from grapevine cells kept in suspen­sion culture was established. The protoplasts were employed in order to perform transient gene expression experiments produced by externally added plasmids. Using the gene coding for bacterial β-glucuronidase as the reporter gene, the transient expression under the control of various promoters of stilbene synthase genes were analyzed. The elicitor-responsiveness of promoters from grapevine genes and heterologous promoters were assayed: the grapevine stilbene synthase gene VST-1 and pine stilbene synthase genes PST-1, PST-2 and PST-3. Compared to the expression effected by the cauliflower mosaic virus 35S RNA-promoter, the stilbene synthase promoters caused a 2-5-fold increase in GUS-activity. Incubation of transformed protoplasts with fungal cell wall further stimulated the stilbene synthase promoters but not the 35S RNA-promoter. An even more pronounced differentiation between the promoters was observed when cGMP was included in the transient expression assays. Instead of treating transformed protoplasts with fungal cell wall we administered simultaneously cGMP and the plasmid to be tested. The cGMP-responsive increase was (a) specific concerning the nucleotide applied, (b) characteristic of grapevine protoplasts, and (c) not seen with shortened promoter-GUS constructs or GUS under the control of the 35S RNA-promoter. The highest cGMP-dependent reponse to stress was shown by the promoter of the grapevine stilbene synthase gene VST-1.
New Sex Attractants for Five Chamaesphecia Species (Lepidoptera, Sesiidae) from the Ukraine and Turkmenistan
Authors: Mozūraitis Raimondas , Būda Vincas , Metleuski Jan 
Published: February 2015

Abstract
Field screening tests of (3Z,13Z)- and (3E,13Z)-octadecadienols, (2Z,13Z)-and (2E,13Z)-octadecadienols and their acetates as well as some binary mixtures of these compounds in dosages of 0.5 mg/dispenser were carried out in the Crimea, the Ukraine, and in the West Kopetdag mountains, Turkmenistan, in 1989-1993. New sex attractants for five clearwing moth species of the genus Chamaesphecia (Lepidoptera, Sesiidae) were discovered. Males of Ch. chalciformis were attracted by a 1:1 mixture of 3Z,13Z-18:OH and 2E,13Z-18:OAc, Ch. schmidtiformis by a 9:1 mixture of 3Z,13Z-18:OAc and 3Z,13Z-18:OH in the Ukraine as well as in the ratios 9:1 and 1:1 in Turkmenistan, Ch. mezentzevi by a 9:1 mixture of 3Z,13Z-18:OAc and the corresponding alcohol, Ch. zimmermanni by a 1:9 mixture of 3Z,13Z-18:OAc and 3.E,13Z-18:OH, and Ch. specia nova in Turkmenistan by a 1:1 mixture of 3Z,13Z-18:OH and 3E,13Z-18:OAc. Two inhibitors, 3Z,13Z-18:OH and 3E,13Z-18:OAc, of the sex attractant were found for Ch. zimmermanni. The periods of attraction to the traps were registered for males of Ch. zimmermanni and Ch. specia nova and were found to occur at 1900-2100 and 1430-1700 local time, respectively. Males of Ch. chalciformis and Ch. schmidtiform is were attracted to the traps in the afternoon.
Solvent Accessibility to Aspartyl and Succinimidyl Residues at Positions 7 and 23 in the Amyloid β 1 - 28 Peptide
Authors: Lins Roberto D. , Soares Thereza A. , Ferreira Ricardo , Longo Ricardo L. 
Published: February 2015

Abstract
The water accessibilities to aspartyl residues at positions 7 and 23 in the amyloid β 1–28 peptide associated with Alzheim er's Disease have been calculated using different techniques. These accessibilities of water were compared to those of the succinimidyl residues (SUC) replacing the aspartyl ones (ASP). It has been possible to ascertain that these modifications (A SP → SUC) lead to a significant increase in the water accessibility to the backbone and a-carbon atom of the SUC7 and SUC23 residues. It is suggested that the spontaneous trans­ formation of ASP → SUC might lead to an increase of the racemization rates due to the higher accessibility of water at these sites. It is also proposed that the behavior of the adjacent residues in the selectivity of the racemization is to control the water accessibility at the reactive residue.
The Anticancer Drug Adriamycin Interacts with the Human Erythrocyte Membrane
Authors: Suwalsky Mario , Hernández Pedro , Villena Fernando , Aguilar Felipe , Sotomayor Carlos P. 
Published: February 2015

Abstract
Adriamycin, Anticancer Drug, Erythrocyte Membrane, Phospholipid Bilayer Adriamycin is an aminoglycosidic anthracycline antibiotic widely used in the treatment of cancer. Increasing reports point to the involvement of cell membranes in its mechanism of action. The interaction of adriamycin with human erythrocytes was investigated in order to determine the membrane binding sites and the resultant structural perturbation. Electron microscopy revealed that red cells incubated with the therapeutical concentration of the drug in human plasma changed their discoid shape to both stomatocytes and echinocytes. Accord­ing to the bilayer couple hypothesis, this means that adriamycin was incorporated into either the inner or outer leaflets of the erythrocyte membrane. To explain this unusual result, the drug was incubated with molecular models. One of them consisted of dimyristoylphosphati-dylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) multilayers, representative of phospholipid classes located in the outer and inner leaflets of the erythrocyte membrane, respectively. X-ray diffraction showed that adriamycin interaction perturbed the polar head and acyl chain regions of both lipids. Fluorescence spectroscopy on another model, consisting of DMPC large unilamellar vesicles (LUV), confirmed the X-ray results in that adriamycin fluidized its hydrophobic moiety. It is concluded that adriamycin incorporates into both erythrocyte leaflets affecting its membrane structure.
Downstream Processing for Xylitol Recovery from Fermented Sugar Cane Bagasse Hydrolysate Using Aluminium Polychloride
Authors: Silva Silvio S. , Ramos Rodrigo M. , Rodrigues C.G.A. , Mancilha Ismael M. 
Published: February 2015

Abstract
Xylitol, a sweetener comparable to sucrose, is anticariogenic and can be consumed by diabetics. This sugar has been employed sucessfully in many foods and pharmaceutical products. The discovery of microorganisms capable of converting xylose present in lignocellulosic biomass into xylitol offers the opportunity of producing this poliol in a simple way. Xylitol production by biotechnological means using sugar cane bagasse is under study in our laboratories, and fermentation parameters have already been established. However, the downstream processing for xylitol recovery is still a bottleneck on which there is only a few data available in the literature. The present study deals with xylitol recovery from fermented sugar cane bagasse hydrolysate using 5.2 g/l of aluminium polychloride associated with activated charcoal. The experiments were performed at pH 9, 50 °C for 50 min. The results showed that aluminium polychloride and activated charcoal promoted a 93.5% reduction in phenolic compounds and a 9.7% loss of xylitol from the fermented medium , which became more discoloured, facilitating the xylitol separation.
Changes of the Photosynthetic Apparatus in Spirulina Cyanobacterium by Sodium Stress
Authors: Verma Kavita , Mohanty Prasanna 
Published: February 2015

Abstract
Spirulina platensis trichomes grown in Zarrouks medium having total Na+ concentration as 0.14 ᴍ when transfered to fresh Zarrouks medium containing enhanced level of Na+ ions equal to 0.86 ᴍ showed 30% more accumulation of Na+ intracellularly as compared to the control. An inhibition of photosystem II activity to almost 66% was observed. Also due to this exposure to high Na+, the room temperature absorption characteristics of Spirulina trichomes and the thylakoid membrane preparations w ere altered indicating changes in the chromophore protein interactions and alterations in the phycocyanin/allophycocyanin ratio; there by affecting the energy harvest and energy transfer processes. An increase in the carotenoid absorption was two fold over the control in the treated sample. Similarly, room temperature and low temperature (77 K) fluorescence emission spectra collectively suggested alterations in the chlorophyll a emissions, F 726 of photosystem I reflecting changes in the lipid protein environment of the thylakoid. Our results indicate that in Spirulina the enhanced Na+ level alters the energy harvest and transfer processes. It also affected the emission characteristics of chlorophyll a of photosystem I.
Study of Xanthine Oxidase Immobilized Electrode Based on Modified Graphite
Authors: Horozova Elena G. , Dimcheva Nina D. , Jordanova Zinaida J. 
Published: February 2015

Abstract
Xanthine oxidase (E . C. 1.2.3.2) was immobilized by adsorption on electrochemically modified graphite plate to obtain an enzyme electrode. The current of the enzyme electrode in substrate (xanthine) solutions was found to be a result of the electrooxidation of H2O2 generated in the enzyme layer. The linearity of the amperometric signal was up to a substrate concentration of 65 μm at 0.6 V (vs. Ag/AgCl). The response time was 2 minutes. The enzyme electrode preserves 80% of its initial activity activity after a three-week storage in air at room temperature.
Antiinfluenza Virus Effect of Extracts from Marine Algae and Invertebrates
Authors: Serkedjieva Julia , Konaklieva Monika , Dimitrova-Konaklieva Stefka , Ivanova Veneta , Stefanov Kamen , Popov Simeon 
Published: February 2015

Abstract
Sixty products, derived from marine organisms, typical of the Bulgarian Black Sea coast, were examined for inhibitory activity on the reproduction of influenza viruses in tissue cultures. The antiviral effect was investigated by the reduction of virus infectivity. Using representative strains of influenza virus it was shown that apparently the inhibitory effect was strain-specific. The most effective products were further studied in fertile hen’s eggs and in experimental influenza infection in white mice.
Flexibility of Amino Acid Residues at Position Four of Nonapeptides Enhances Their Binding to Human Leucocyte Antigen (HLA) Molecules
Authors: Chersi Alberto , Modugno Francesca di , Rosano Laura 
Published: February 2015

Abstract
The binding affinity of synthetic nonapeptides to human leucocyte antigens (HLA) molecules of the A0201 allotype, the most common in Caucasian, is enhanced or reduced by suitable amino acid substitutions at position 4, as a result of increased or decreased chain flexibility. A higher flexibility of the bond at this position correlates with an easier accomodation of the fragment into the HLA groove, while rigidity of the peptide chain appears to interfere. These data are based on two lines of evidence: a) most natural high affnity ligands for HLA-A0201 possess, at position 4, flexible residues b) substitutions of such residues by rigid amino acids results in a decrease of binding affinity.
A New Cucurbitacin Glycoside from Kageneckia oblonga (Rosaceae)
Authors: Muñoz Orlando , Delporte Carla , Backhouse Nadine , Erazo Silvia , Negrete Rosa , Maldonado Sergio , López-Pérez José L. , Feliciano Arturo San 
Published: February 2015

Abstract
A novel cucurbitacin glycoside has been isolated from aerial parts of Kageneckia oblonga R. et P. and shown to be 3β-(β-D-glucosyloxy)-16α,23α-epoxycucurbita-5,24-dien-11-one. The structure was established by usual spectroscopic and two-dimensional (2D ) NMR techniques. This compound has found to be nontoxic when tested in-vivo cell culture assays. In previous investigations we reported 23,24-dihydrocucurbitacin F and prunasine. This was the first report on cucurbitacins from the genus Kageneckia (Rosaceae).
Use of Immobilized Candida Cells on Xylitol Production from Sugarcane Bagasse
Authors: Carvalho Walter de , Silva Silvio Silvério da , Vitolo Michele , Mancilha Ismael Maciel de 
Published: February 2015

Abstract
In this study we used the yeast Candida guilliermondii FTI 20037 immobilized by entrapment in Ca-alginate beads (2 .5 -3 mm diameter) for xylitol production from concentrated sugarcane bagasse hemicellulosic hydrolysate in a repeated batch system. The fermentation runs were carried out in 125- and 250-ml Erlenmeyer flasks placed in an orbital shaker at 30 °C and 200 rpm during 72 h, keeping constant the proportion between work volume and flask total volume. According to the results, cell viability was substantially high (98%) in all fermentative cycles. The values of parameters xylitol yield and volumetric productivity increased significantly with the reutilization of the immobilized biocatalysts. The highest values of xylitol final concentration (11.05 g/1), yield factor (0.47 gig) and volumetric productivity (0.22 g/lh) were obtained in 250-ml Erlenmeyer flasks containing 80 ml of medium plus 20 mi of immobilized biocatalysts. The support used in this study (Ca-alginate) presented stability in the experimental conditions used. The results show that the use of immobilized cells is a promising approach for increasing the xylitol production rates.