bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pentacyclic Triterpenes and Other Constituents from Ficus cordata (Moraceae)
Authors: Poumale Herve M. P. , Kengap Rodrigue T. , Tchouankeu Jean Claude , Keumedjio Felix , Laatsch Hartmut , Ngadjui Bonaventure T. 
Published: August 2018

Abstract
Two new pentacyclic triterpenes 8,26-cyclo-urs-21-en-3β, 20β-diol (1) and 3β-acetoxy-8.26- cyclo-ursan-20β-ol (2) together with 3-friedelanone, oleanolic acid, betulinic acid, lupeol acetate, α- and β-amyrine, S.SJ^'-tetrahydroxyflavane, and 3,5,7,3',4'-pentahydroxyflavane were isolated from the stem bark of Ficus cordata (Moraceae). The structures of these secondary metabolites were established using ID and 2D NMR spectra and by comparison with published data or with authentic samples. Compounds 1 and 2 exhibited weak antibacterial and no antifungal activity.
The acidic ionic liquid [BSO3HMIm]HSO4: a novel and efficient catalyst for one-pot, three-component syntheses of substituted pyrroles
Authors: Luo Yuan , Zhang Bao-Qiang , He Yan-Hong , Guan Zhi 
Published: August 2018

Abstract
An acidic ionic liquid 3-methyl-2-(1-sulfobutyl)-1H-imidazolium hydrogensulfate, [BSO3HMIm]HSO4, was used as an efficient catalyst for the synthesis of a variety of pyrrole derivatives via a one-pot, three-component condensation of amines, nitroolefins, and 1,3-dicarbonyl compounds. Good to excellent yields of 72–96% were obtained under reflux in ethanol. The catalyst could easily be recovered and recycled up to six times, resulting in good yields without prolonging the reaction time. This method was also efficient in large-scale preparation. The procedure could be easily expanded to a one-pot, four-component reaction. This ionic liquid-catalyzed reaction provided an environmentally friendly alternative to the synthesis of pyrrole derivatives.
Synthesis and structural characterization of substituted phenols with a m-terphenyl backbone 2,4,6-R3C6H2OH (R=2,4,6-Me3C6H2, Me5C6)
Authors: Şolea Atena B. , Olaru Marian , Silvestru Cristian , Raţ Ciprian I. 
Published: August 2018

Abstract
Substituted phenols with a m-terphenyl backbone 2,4,6-R3C6H2OH [R=2,4,6-Me3C6H2 (1), Me5C6 (2)] were synthesized using Kumada cross-coupling reactions between 2,4,6-I3C6H2OH and the corresponding Grignard reagent. Both compounds were structurally characterized in solution by 1H and 13C NMR spectroscopy and HRMS. The molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction.
“Naked” S2O7
2– ions – the serendipitous formation of the disulfates [HPy]2[S2O7] and [bmim][HPy][S2O7] (HPy = pyridinium; bmim = 1-Butyl-3-methylimidazolium)
Authors: Bruns Jörn , Logemann Christian , Weiz Alexander , Kolb Claudia , Wickleder Mathias S. 
Published: August 2018

Abstract
[bmim][HPy][S2O7] [monoclinic, P21/n, Z = 4, a = 825.78(2), b = 1545.30(3), c = 1410.80(3) pm, β = 104.726(1)°, V = 1741.16(7) Å3] was obtained as a side product in the reaction of GeCl4, oleum (65% SO3), and the pyridine (Py) complex Py·SO3 in the ionic liquid 1-butyl-3-methylimidazolium hydrogensulfate, [bmim][HSO4], at 50 °C. Charge compensation of the disulfate ion is achieved by the counterions pyridinium, [HPy]+, and 1-butyl-3-methylimidazolium, [bmim]+. The crystal structure shows alternating layers of [bmim]+ cations on one hand and [HPy]+ cations and disulfate anions on the other hand. Pyridinium disulfate, [HPy]2[S2O7] [orthorhombic, P212121, Z = 4, a = 801.35(1), b = 1257.62(2), c = 1357.22(3) pm, V = 1367.80(4) Å3] was formed unexpectedly in the reaction of Eu2O3 and Py·SO3 in pyridine. The crystal structure exhibits a layer-like arrangement of disulfate and pyridinium moieties in the ab plane. In both compounds, the disulfate groups are essentially uncoordinated allowing for a detailed inspection of “naked” S2O7
2– ions.
New transition metal-rich rare-earth palladium/platinum aluminides with RET
5Al2 composition: structure, magnetism and 27Al NMR spectroscopy
Authors: Benndorf Christopher , Stegemann Frank , Eckert Hellmut , Janka Oliver 
Published: August 2018

Abstract

REPd5Al2 compounds with RE = Ce–Gd as well as Y and Lu have been previously synthesized. Although some compounds with the small lanthanides also exist, the compounds with intermediate-sized rare-earth elements (RE = Tb–Yb) had not been prepared. We report on the missing members of the REPd5Al2 (RE = Tb–Yb) series as well as on the new REPt5Al2 (RE = Y, Gd–Tm, Lu) series, which we have synthesized and structurally as well as magnetically characterized. All members crystallize isostructurally in the ZrNi2Al5 type with an anti-arrangement of the T = Pd/Pt and Al atoms. YPd5Al2 and LuPd5Al2, as well as the respective platinum homologs, YPt5Al2 and LuPt5Al2, have been characterized also by 27Al magic-angle spinning nuclear magnetic resonance spectroscopy. Consistent with the XRD analysis, the spectra indicate the existence of only one distinct Al site in the structure.
Reactions of Antisera to Lutein and Plastoquinone with Chloroplast Preparations and their Effects on Photosynthetic Electron Transport
Authors: Radunz Alfons , Schmid Georg H. 
Published: August 2018

An antiserum to lutein inhibits photosynthetic electron transport between water and potassium ferricyanide in diloroplasts from green Nicotiana tabacum var. John William’s Breadleaf. However, electron transport between diphenylcarbazide and potassium ferricyanide is not impaired. From this it is concluded that the photochemically active carotenoid should feed its electrons into the photosynthetic electron transport chain before the site from which diphenyl-carbazide donates electrons. The inhibition of the ferricyanide Hill reaction in diloroplasts by antibodies to lutein depends on the accessibility of the carotenoid antigen in the thylakoid membrane. In fresh preparations the accessibility is greater in diloroplasts in which photo- synthetic electron transport is coupled to photophosphorylation. Concomitantly the antiserum to lutein agglutinates only such chloroplast preparations in which the Hill reaction is impaired by the antiserum.
An antiserum to plastoquinone inhibits ferricyanide photoreduction of diloroplasts regardless whether driven by water or diphenylcarbazide as the electron donors. Typical photosystem-I-reactions are not influenced by the antiserum. In a certain type of chloroplast preparations the antiserum does not inhibit PMS-mediated photophosphorylation inferring that plastoquinone, eventually involved in this reaction, is either not accessible to antibodies, or that this cyclic electron flow does not necessarily pass through plastoquinone.
Heterogeneity of the Native Ribosomal Subunit Fraction in HeLa Cells
Authors: Lecou Christian , Arends Sigrid , Liautard Jean-Pierre , Köhler Kurt 
Published: August 2018

The cytoplasm of growing HeLa cells contains a certain quantity of native ribosomal subunits. They constitute a heterogeneous fraction consisting of at least two categories of particles.
The first category comprises the newly emerging native 40S subunits which do not form 80S couples under any in vitro condition tried. It is postulated that these native subunits carry an anti-association factor which cannot be stripped off by 0.5 м KCl treatment.
Transiently native subunits of the second category reassociate to 80S ribsomes only in the presence of an association factor.
Mode of Replication and Temperature Characteristics of the RNA Polymerase of an Influenza Virus in vitro
Authors: Paffenholz Volker , Scholtissek Christoph 
Published: August 2018

While the enzyme template complex of fowl plague virus (FPV) polymerase is rather stable during incubation in vitro, some of the newly synthesized RNA is degraded rapidly. At low temperatures a pronounced lag phase of RNA synthesis occurs, which can be prevented by incubation with substrate. The in vitro products are initially single-stranded RNA, which are converted to partially double-stranded molecules by phenol and SDS. The results are compatible with an open replicative intermediate structure, in which the newly synthesized RNA is bound to the complementary template only over a rather short region at the growing point.
A comparison of the temperature characteristics of the RNA polymerases of the highly virulent FPV with that of the low pathogenic virus N revealed that the lag phase is a virusspecific property. There appears to exist a correlation between virulence and heat stability of this enzyme, the activity of which is rate limiting at the normal temperature of the host (41 °C).
Radioprotection (UV-and Gamma-rays) of DNA Molecule by Indole and Indole-derivatives
Authors: Tomicic I. , Pieber M. , Romero C. , Soto A. , Tohá J. C. 
Published: August 2018

Abstract
The radioprotective ability of ʟ-tryptophan, tryptamine, 3-indoleacetic and indole (10-4 ᴍ), on UV and gamma irradiated DNA (10-4 ᴍ) is studied.
UV radioprotection is accomplished in the following order of efficiency: ʟ-Tryptophan and 3-indoleacetic acid > indole and tryptamine. The corresponding DRF measured as absorbancy loss at 260 nm, were: ʟ-Tryptophan and 3-indoleacetic acid around 3 and tryptamine and indole around l. When absorbancy loss plus changes in the patterns of the absorbancy curve were con­ sidered the DRF was: L-Tryptophan 2.53, 3-indoleacetic acid 1.54, indole 1.22 and tryptamine 0.75, respectively.
For gamma radiation damage the order of radioprotection found was: Indole, ʟ-tryptophan and tryptamine > 3-indoleacetic acid. The DRF when compairing the absorbancy loss at 260 nm, were: ʟ-Tryptophan, Indole and tryptamine around 11 and 3-indoleacetic Acid around 4. When evaluating total changes in absorbancy the DRF were: Indole and ʟ-tryptophan around 6.5, tryptamine 3.7 and 3-indoleacetic 2.1.
These data were correlated with measurement of the degree of molecular interactions of DNA and protectors, studied by: Spectrophotometry, m.p. determinations, circular dichroism and oriented circular dichroism, viscosity, and rate of dialysis. Also data of fluorescence and phosphorescense were considered.
For gamma radioprotection a mechanism based in radical trapping, local radical trapping and partial recovery of radioprotectors is proposed.
UV radioprotection is discussed considering: The close interaction of L-tryptophan with DNA which might impede dimer formation, its proton and electron donor ability. A possible (triplet-triplet) energy transfer from excited DNA to indole derivative is discussed on the basis of acetone competition and a dimer excision process considered.
Der Verlauf der Lipochinon- und Pigmentsynthese bei einer experimentell induzierten Chloroplastendegeneration in grünen Keimlingen von Hordeum vulgare L. / Kinetic of Lipoquinone and Pigment Synthesis during an Experimentally Induced Chloroplast Degeneration in Green Seedlings of Hordeum vulgare L.
Authors: Grumbach K. H. , Lichtenthaler H. K. 
Published: August 2018

Within a dark period of 24 hours green Hordeum plants change their lipoquinone and carotenoid metabolism to that of etiolated plants. A longer darkness induces degeneration of chloroplasts with a concomitant destruction of pigments and lipoquinones which is similar to that of the natural chloroplast degeneration in leaves.
1. The chlorophyll and vitamin Kt content is not augmented in the dark, but decreases. The concentration of the oxidized benzoquinones plastoquinone-9 and α-tocoquinone decreases rapidly whereas the level of plastohydroquinone-9 is augmented until 24 hours darkness. α-Tocopherol in turn is accumulated throughout the dark period.
2. Among the carotenoids β-carotene is considerably enriched only in the first 24 hours of the dark period. Xanthophylls are accumulated up the 3 days. The successive increased appearance of single carotenoids during the dark period corresponds to their biogenetic sequence. During carotenoid breakdown (after the 3rd day) neoxanthin, as common oxidation product of all carotenoids appears as the main carotenoid component.
3. It is postulated that the accumulation of the reduced quinone forms (α-tocopherol, plastohydroquinone- 9) in the dark, which has been shown here, also occurs in the dark phase during natural day-night growth of plants and thus gives rise to the continuous accumulation of a-tocopherol and plastohydroquinone-9 in chloroplasts, as described before 4.
Gaschromatographisch-massenspektrometrische Differenzierung von Erdbeerarten / Gaschromatographical-masspectrometrical Differentiation of Aroma Substances from Strawberries
Authors: Drawert Friedrich , Tressl Roland , Staudt Günter , Köppler Hans 
Published: August 2018

Abstract
Ripe fruits of wild growing varieties of strawberries had been homogenized under inhibition of the enzymes and extracted with the adding of an internal standard. About 40 main components could be identified and quantitatively determined by gaschromatographical-mass-spectrometrical investigations. Methyl ketones and secondary alcohols dominate in Fragaria moschata and Fragaria vesca, whereas especially ethylesters of the carboxylic acids C6 to C12 are formed by Fragaria chiloensis. Fragaria virginiana contains numerous components amongst which are especially the methyl-and ethylesters of the carboxylic acids C6 to C12; besides it contains, as distinctive marks, n-butyl-, n-hexyl, ra-octyl, and n-decylesters of the carboxylic acids C4 to C10 . All varieties exhibit a sorttypical distribution pattern of the aroma components.
Zur Thermodynamik der hydrophoben Wechselwirkung; die Systeme Wasser + Glycin+ Harnstoff und Wasser + Alanin+ Harnstoff bei 25 °C / Thermodynamics of Hydrophobie Interaction in the Systems Water + Glycin + Urea and Water + Alanin + Urea at 25 °C
Authors: Rafflenbeul Lothar , Pang Wa-Ming , Schönert Hansjürgen , Haberle Klaus 
Published: August 2018

Abstract
Isopiestic vapor pressure measurements and calorimetric determination of the heat of dilution have been performed and evaluated with respect to enthalpy, entropy and free enthalpy in the ternary solutions water+ glycin+ urea and water+ alanin + urea. The free enthalpy of transfer for the process: Amino acid from water to water+ urea, which can be derived from these measurements, does not agree with the value calculated from solubility measurements. The reason for this discrepancy and the values of entropy and enthalpy in terms of hydrophobic interaction are discussed. Supplementary measurements of the proton magnetic resonance in these solutions are included.
Evidence for the Validity of Three-Component Fitting of Protein Circular Dichroism Spectra
Authors: Bannister W. H. , Bannister J. V. 
Published: August 2018

Abstract
The validity of three-component fitting of protein circular dichroism (CD) spectra in the peptide absorption region with basis spectra for helical, β-sheet and unordered structure is examined by matrix rank analysis of protein CD spectra. It is shown that a three-component basis can be justified for several proteins within the limits of experimental error of the spectra. It is suggested that the fitting of protein CD spectra with basis spectra derived from reference proteins should be preceded by matrix rank analysis to show that the CD spectra of the reference and unknown proteins have the same basis.
Identification of Radiolysis Products of Cytosine Resulting from the Deamination Pathway
Authors: Polverelli M. , Teoule R. 
Published: August 2018

Abstract
Radiolysis products resulting from the deamination pathway were isolated and identified after irradiation of cytosine by gamma rays in neutral aqueous solutions. They were identical to those identified in uracil radiolysis i. e. 5,6-dihydroxy-5,6-dihydro-uracil (cis and trans forms), iso-dialuric acid, alloxan, 5-hydroxy-hydantoin, parabanic acid and oxaluric acid.
The absence of 4,4′-di-iso-barbituric acid, alloxantin or iso-barbituric acid could be explained by the good stability of uracil glycols. The identification of buiret proof of potential degradation mechanisms different from these involving of the free radical attack on the 5,6 double bond. Gamma Irradiation of Cytosine in an Aerated Aqueous Solution, I
Die radioaktive Markierung des Melaninpigments der Fischhaut mit [35S]Natriumsulfat Radioactive Labelling of the Melanin Pigment in Fish Skin with [35S] Sodium Sulphate
Authors: Plesse Dieter , Lüdicke Manfred 
Published: August 2018

Abstract
[35S]Sodium sulphate was intraperitoneally injected into adult fishes and its incorporation into melanins examined. Relevant incorporation of the tracer into normal skin and peritoneal melano­ cytes of Poecilia reticulata (Peters) and Puntius tetrazona tetrazona (Hamilton) could be detected only in rare cases. Melanocytes of malignant melanomas in the hybrids of Xiphophorus helleri (Heckel) and Platypoecilus maculatus (Guenther) exhibited a different degree of radioactivity ac­ cording to their degree of differentiation. The isolation of the melano-protein complex from melanocytes of these melanomas and its subsequent hydrolysis resulted in the following: During melanin synthesis, [35S] sulphate had been incorporated into the chromophore group as an ester-sulphate, whereas no significant incorporation of the tracer was found in the protein matrix.
Suggestive Evidence for an Oncorna-Virus-Specific DNA Polymerase from C-Type Particles of Bovine Leukosis
Authors: Dietzschold B. , Kaaden O.R. , Ueberschaer S. , Weiland F. , Straub O. C. 
Published: August 2018

Abstract
Typical C-type oncorna virus particles as shown by electron microscopy have been purified from the supernatant of cultured lymphocytes from bovine leukosis. In the purified C-particle fraction a DNA-polymerase activity was detected. Using several synthetic RNA-or DNA-homopolymers and 70S Friend virus RNA the template response of this bovine leukosis cell particle DNA polymerase was compared with those of feline leukaemia virus DNA polymerase and DNA polymerase from normal bovine lymphocytes. The DNA polymerase detected in the viral preparation of bovine leukosis is suggested to be an oncorna-virus-specific enzyme.
Der Einfluß von 4-Hydroxy-2.3-pentenal (HPE) auf die Vermehrung von Vaccinia-Virus in Hühnerfibroblastenkulturen / Influence of 4-Hydroxy-2,3-pentenale (HPE) on the Multiplication of Vaccinia-virus in Chick-embryo Fibroblast Cultures
Authors: Dostal V. , Schauenstein E. , Kulnigg P. , Schmeller E. 
Published: August 2018

Abstract
The influence of 4-hydroxy-2,3-/rans-pentenale (HPE) on multiplication of Vaccinia virus in chick fibroblast cultures has been investigated. The cytotoxicity of HPE has been estimated by in ­ corporation of [3H] thymidine, [3H] uridine, [3H] leucine and by morphological tests. The greatest influence of H PE was seen after incorporation of [3H] thymidine.
Chick-embryo cultures infected with Vaccinia virus showed a marked increase of DNA synthesis in contrast to the controls. This increase averaged 180% after 16 to 14 hours. HPE 0.05-10_ 3 M caused a reduction of 72% in [3H] thymidine incorporation in virus infected cultures. At the same time virus concentration decreased by 76%. HPE 0.1-10~3 M, a concentration which inhibits the normal cell DNA synthesis by 50%, caused about 90% inhibition in infected cultures; virus m ulti­ plication was 99% inhibited. These findings have been attributed to a selective inhibition of virus DNA synthesis by HPE. and possible mechanisms are discussed.
Charge-Transfer Interactions between Nucleobases and Metal Ions: ESR and Optical Absorption Studies
Authors: Lohmann Wolfgang , Hillerbrand Max , Klenert Max 
Published: August 2018

Abstract
The charge-transfer interaction of different nucleobases with Cu2+ has been investigated by means of ESR and optical absorption studies. It could be shown that cytosine forms the strongest complex. The greatest reduction of Cu2+ (that is, spin concentration) was obtained, however, with adenine. Based on these results the following order for the electron donor strength of the nucleo­bases has been obtained: Ade>Cyt>Thy>Ura.
Studies on Purine-Pyrimidine Hydrogen Bonded Base Pairing by Means of Absorption and Emission Spectroscopy
Authors: Wagner Wanda , Zaborowska Maria , Puzyna Wlodzimierz , Shugar David 
Published: August 2018

Abstract
Procedures are described for measurement of association constants between potentially com­plementary purine and pyrimidine bases by hydrogen bonding in non-aqueous medium by means of absorption and emission spectroscopy. The methods require that one of the two constituents be fluorescent and exhibit a long wavelength absorption band not, or only partially, overlapped by the second constituent. The foregoing has been applied to measurements of the association constants, and other parameters, of hydrogen-bonded complexes of 2-aminopurine with 1-substituted uracil, thymine and barbital in chloroform solution, both in the ground and excited states. It was estab­lished that the 1:1 hydrogen-bonded base pairs 2-aminopurine : 1-cyclohexyluracil and 2-amino­ purine: 1-octylthymine maintain the ground-state equilibrium during the life time of the excited state, whereas for the corresponding pair 2-aminopurine: 1-methylbarbital this equilibrium is per­ turbed on excitation. The influence of N-alkylation of the 2-aminopurine residue on base-pairing with the pyrimidines has also been examined. The results are compared with those obtained by other methods. The specific advantages of the procedures employed, and their possible applications to studies on the behaviour of fluorescent residues in polynucleotides, are discussed.
Mobility of Chloroplast Coupling Factor 1 (CF1) at the Thylakoid Surface as Revealed by Freeze-Etching after Antibody Labelling
Authors: Berzborn Richard , Kopp Friedrich , Mühlethaler Kurt 
Published: August 2018

Abstract
Freeze-Etching Freeze-fracturing and 60 sec deep-etching of isolated chloroplast thylakoid systems exposed large areas of the outer surface (matrix side) of the thylakoids. If the thylakoid systems were first treated with antisera against chloroplast coupling factor 1 (CF1), the 14 nm particles at the outer surface appeared aggregated. Between clusters these particles were absent. Since there is no change in the number of particles/area after treatment with antibodies, it is concluded that the 14 nm particles are mobile within the surface of the thylakoid. The antisera contained only anti­bodies against CF1 ; therefore the 14 nm particles at the outer surface are identified to be CF1 . The implication of a mobile ATP-synthetase (CF1) for the mechanisms of photophosphorylation is discussed.
Studies on the Effect of Diphenylcarbazide in Isolated Chloroplasts from Spinach
Authors: Harnischfeger Götz 
Published: August 2018

Abstract
The influence of diphenylcarbohydrazide (DPC) on electron transport parameters of chloroplasts was studied through the use of hypotonically disintegrated plastids in various states of membrane disarray.
The observation that DPC acts as donator for PS II when the natural source becomes inefficient was confirmed.
Contrary to prior contentions oxygen evolution is not diminished upon addition of DPC.
A definite though transient influence of DPC on the pigment system was detected. At a certain state of structural disarray DPC increases the quantum yield and electron transport efficiency through PS II, while simultaneously decreasing the activity of PS I. The effect is not based on addition or removal of individual pigments to the pigment complexes. The analysis of light inten­sity curves and fluorescence kinetics suggest a better migration of trapped light to open reaction centers.
The results are discussed for possible implications on the analysis of the oxygen evolving system as well as on spillover mechanisms.