bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Modelling of the Interaction of Cyanoacrylate Inhibitors with Photosystem II Part 1. The Effect of Hydrophobicity of Inhibitor Binding
Authors: Mackay Simon P. , O’Malley Patrick J. 
Published: August 2018

Abstract
Cyanoacrylate Inhibitors, Photosystem II, Hydrophobicity The secondary quinone binding site of photosystem II is also the binding site for many dif­ ferent herbicides. The 2-cyanoacrylate inhibitors are a potent class of electron transfer inhibi­tors which bind at this site and are extremely sensitive to minor structural variation. In order to understand their mode of binding, we have studied the interaction between the inhibitors and receptor in the D1 protein binding region (residues Leu 210 to Val 280) in terms of non­ bonded intermolecular forces. The intermolecular energy was calculated by van der Waals and electrostatic interactions after energy minimization of the combined structures to reduce inter and intramolecular strain. We have identified specific amino acid residues within the binding protein which are instrumental in binding the herbicide and have shown that the spatial arrangement of the herbicide functional groups within the binding site rather than their lipo­philicity is the determining factor in binding efficiency.
Intersexual Transfer of a Toxic Terpenoid during Copulation and Its Paternal Allocation to Developmental Stages: Quantification of Cantharidin in Cantharidin-Producing Oedemerids (Coleoptera: Oedemeridae) and Canthariphilous Pyrochroids (Coleoptera: Pyrochroidae)
Authors: Holz C. , Streil G. , Dettner K. , Dütemeyer J. , Boland W. 
Published: August 2018

In whole body extracts of the canthariphilous pyrochroid Schizotus pectinicornis and the cantharidin-producing oedemerid Oedemera femorata cantharidin contents were determined by means of quantitative gas chromatography. Adults and all developmental stages of both species contain this terpenoid, but in considerably different amounts. Cantharidin contents differ significantly between the sexes of adult O. femorata: 8.4 μ,g/female, 3.5 μg/male. Values for Sch. pectinicornis are more than 30-fold lower than those of O. femorata and no intersexual difference in the cantharidin content could be detected. Eggs of O. femorata contained cantharidin and larvae of this species are capable of synthesizing this terpenoid. The total amount of cantharidin increases in successive instars. In Sch. pectinicornis, the content of cantharidin decreases from egg to first instar.
Feeding and copulation experiments with [2H2]cantharidin indicate that in O. femorata no or only very small amounts of cantharidin are transferred from males to females at copulation. Thus, males do not invest in the protection of their offspring by cantharidin gifts to the mate. For Sch. pectinicornis an intersexual transfer of labelled cantharidin during copulation was detected. About 45% of the entire cantharidin content in mated females derived from fed males. Analyses of eggs and first instar larvae show that a paternal allocation of 2[H2]cantharidin to developmental stages exists for this canthariphilous pyrochroid.
Aloe Plants Accumulate Anthrone-Type Anthranoids in Inflorescence and Leaves, and Tetrahydroanthracenes in Roots
Authors: Sigler Anette , Rauwald Hans W. 
Published: August 2018

Abstract
The accumulation and distribution of characteristic secondary products in the different organs of an Aloe plant (A. succotrina Lam.) were studied by high performance liquid chromatography for the first time. In the leaves of the Aloe plant, only anthrone-C-glycosyls of the 7-hydroxyaloin type and, for the first time in plant material, the free anthraquinone 7-hydroxyaloeemodin were found. In contrast to previous reports on the distribution of secondary products in Aloe plants, anthrone-C-glycosyls were also detected in flowers, bracts and the inflorescence axis of the species examined. Aloesaponol I, a tetrahydroanthracene aglycone, was only present in the underground organs and in the stem. The 2-alkylchromone-C-glucosyl aloeresin B showed no specific occurrence as it was found in every type of organ. Based on these results and the findings of recent studies on Aloe roots and flowers, a distri­bution scheme of polyketide types in the Aloe plant was established. It suggests a separate and independent anthranoid metabolism for underground Aloe organs and stem on the one hand, and for leaves and inflorescence organs on the other hand. In the latter structures anthranoid metabolism seems to be additionally compartmentalized as the anthranoid pro­ files of inflorescence organs and leaves differ in two points relevant to anthranoid biosynthe­ sis: firstly, the occurrence of anthrone aglycones and secondly, the individual content of corre­sponding anthrone-C-glucosyl diastereomers.
Hyphodontal, a New Antifungal Inhibitor of Reverse Transcriptases from Hyphodontia sp. (Corticiaceae, Basidiomycetes)
Authors: Velten Robert , Gimenez Alberto , Steglich Wolfgang 
Published: August 2018

Abstract
In a search for inhibitors of RNA-directed DNA polymerases a new isolactarane sesquiterpenoid, hyphodontal (1), was isolated from fermentations of a Canadian Hyphodontia species. Its structure was elucidated by spectroscopic methods. Hyphodontal strongly inhibits the growth of several yeasts and is a non-competitive inhibitor of avian myeloblastosis virus (Ki 346 μᴍ) and Moloney murine leukemia virus (Ki 112 μᴍ) reverse transcriptases. In addition, cytotoxic and antifungal activities were observed.
Molecular Systematics of the Nepetoideae (Family Labiatae): Phylogenetic Implications from rbcL Gene Sequences
Authors: Kaufmann Martina , Wink Michael 
Published: August 2018

Abstract
Total DNA was extracted from 41 species (20 genera) of the subfamily Nepetoideae (family Labiatae). Using rbcL-specific primers, the rbcL gene was amplified by polymerase chain reaction (PCR) and sequenced directly. RbcL sequences were evaluated with character state (maximum parsimony; PAUP) and distance methods (neighbour-joining; MEGA). In agree­ ment with classical systematics all taxa studied cluster within the Nepetoideae and are clearly distinguished from members of the subfamily Lamioideae. A number of distinctive clades are apparent within the Nepetoideae:, and XIII -Perovskia. At least five main branches rep­ resenting the clades I, II, III to VII, VIII, and IX to XIII respectively, can be distinguished within the Nepetoideae studied. They might be considered representing the tribes (according to Cantino, 1992) Elsholtzieae (I), Lavanduleae (II), and Mentheae (III - XIII). The tribe Mentheae needs to be subdivided into at least three main groups (clades III-VII, VIII and IX -XIII). Major ana hortensis which is often classified as Origanum hortensis does not cluster with Origanum and deserves a generic status of its own.
New Emitter-Detector-Cuvette Assembly for Measuring Modulated Chlorophyll Fluorescence of Highly Diluted Suspensions in Conjunction with the Standard PAM Fluorometer
Authors: Schreiber Ulrich 
Published: August 2018

Abstract
A new emitter-detector-cuvette assembly for the standard PAM fluorometer is described which leads to substantial improvement of signal/noise ratio and increased flexibility with respect to the choice of excitation and emission wavelengths. These features are particularly useful for work with very dilute suspensions of unicellular algae and isolated chloroplasts. Instead of fiber optics perspex rods are applied for guiding excitation light to a mirrored 10×10×45 mm cuvette and from there at 90° angle to the photodetector, similarly as recently reported for a PAM fluorometer based on Xe-flash measuring light (Schreiber et al. (1993), Photosynth. Res. 36, 65-72). While the detection limit of the new system does not reach that of the Xe-PAM fluorometer, it is approximately two orders of magnitude higher than that of the standard system. Rapid induction kinetics can be measured at low chlorophyll concen­ trations down to 0.1 μg · ml-1. Satisfactory quenching analysis for detection of active chloro­ phyll concentration is still possible at 5 μg chlorophy · l-1 . The various optical factors con­ tributing to the improved sensitivity are analyzed. An accessory device is described by which the frequency of the measuring light pulses generated by the PAM fluorometer is lowered in order to reduce the actinic effect of the measuring light. The performance of the new system using different excitation and emission wavelengths is demonstrated in measurements with green algae, cyanobacteria and leaves. Applying a newly available blue light-emitting diode with 450 nm peak emission, short wavelength fluorescence enriched in PS II emission can be measured, which is characterized by high values of variable fluorescence relative to maximal fluorescence. Using measuring light covering five different wavelength ranges the fluorescence contributions from cyanobacteria and green algae can be distinguished on the basis of distinct differences in their excitation spectra. This approach should become useful for an estimation of content and activity of different types of phytoplankton in natural surface waters.
Further Flavonoids and Other Phenolics of Thymus webbianus Rouy
Authors: Blázquez María Amparo , Máñez Salvador , Zafra-Polo María Carmen 
Published: August 2018

Abstract
Seven different flavonoids from the aerial parts of Thymus webbianus were isolated. They were identified by UV spectra, TLC and HPLC-DAD as luteolin, api­genin, eryodictiol, naringenin, luteolin-7-O-glucoside, apigenin-7-O-glucoside and apigenin-6,8-di-C-glucoside. Other phenolics characterized by HPLC-DAD analysis were: protocatechuic, chlorogenic, syringic, p-coumaric and 3,5-dicaffeoylquinic acids.
Kuehneromycins A and B, Two New Biological Active Compounds from a Tasmanian Kuehneromyces sp. (Strophariaceae, Basidiomycetes)
Authors: Erkel Gerhard , Lorenzen Kirsten , Anke Timm , Velten Robert , Gimenez Alberto , Steglich Wolfgang 
Published: August 2018

Abstract
In a search for new inhibitors of RNA-directed DNA-polymerases kuehneromycin A (1) was isolated from fermentations of a Tasmanian Kuehneromyces species. Its structure was elucidated by spectroscopic methods. Kuehneromycin A (1) is a non-competitive inhibitor of avian myeloblastosis virus (Ki 200 μᴍ) and moloney murine leukemia virus (Ki 40 μᴍ) reverse transcriptases. The second compound, kuehneromycin B (2) is a strong inhibitor of platelet aggregation stimulated with different inducers. In addition, both compounds exhibit cytotoxic and antimicrobial activities.
Chemical Structure-Odor Correlation in a Series of Synthetic n-Nonen-1-ols
Authors: Sakoda Yasunobu , Matsui Kenji , Kajiwara Tadahiko , Hatanaka Akikazu 
Published: August 2018

In order to elucidate chemical structure-odor correlation in the all isomers of n-nonen-1- ols, an entire series of these alcohols were synthesized stereo-selectively in high purity. For unequivocal syntheses of them, geometrically selective hydrogenation of the respective acetylenic compound was adopted. The synthesized alcohols were converted to their 3,5-dinitrobenzoate derivatives with 3,5-dinitrobenzoyl chloride, and then purified by repeated recrystallization.
Chemical structure-odor correlations in all the isomers of n-nonen-1-ols were elucidated by introducing a novel method to evaluate odor characteristics and by treating the obtained data statistically with the principal component analysis method (Cramer et al., 1988). The odor profiles of the tested compounds were attributable largely to the positions of the carbon- double bond. The geometries of compounds had only a little effect. With the principal component analysis, the odor profiles of the series of compounds were successfully integrated into the first and the second principal components. The first component (PC-1) consisted of combined characteristics of fruity, fresh, sweet, herbal and oily-fatty, in which herbal and oily-fatty were conversely correlated each other to the position of double-bond of the tested compounds. Of these, only (6Z)-nonen-1-ol deviated markedly from the correlation, indicative of some special interaction between the spatial structure of this compound and the sensory machinery of human.
Chemical Composition and Antibacterial Activity of Brazilian Propolis
Authors: Bankova V. , Christov R. , Kujumgiev A. , Marcucci M. C. , Popov S. 
Published: August 2018

Abstract
Four samples of Brazilian propolis were investigated by GC/MS of different fractions. 32 volatile compounds, (10 of them new for propolis), as well as 12 more polar compounds (one of them new for propolis) were identified. Antibacterial activity was found in some propolis fractions.
Isomerization and Peroxidizing Phytotoxicity of Thiadiazolidine-thione Compounds
Authors: Iida Tetsuji , Senoo Satoshi , Sato Yukiharu , Nicolaus Beate , Wakabayashi Ko , Böger Peter 
Published: August 2018

Abstract
Eight 5-arylimino-3,4-tetramethylene-1,3,4-thiadiazolidine-2-thiones and eight 4-aryl-1,2- tetramethylene-1,2,4-triazolidine-3,5-dithiones were synthesized and their phytotoxic activities were investigated using sawa millet (Echinochloa utilis), green microalgae (Scenedesmus acutus) and protoporphyrinogen-IX oxidase isolated from etiolated corn (Zea mays) seedlings. 5-Arylimino-3,4-tetramethylene-1,3,4-thiadiazolidine-2-thiones showed strong phytotoxic activities and the same herbicidal mode of action as known for peroxidizing herbicides. 5-Arylimino-3,4-tetramethylene-1,3,4-thiadiazolidine-2-thiones were not or very little converted into 4-aryl-1,2-tetram ethylene-1,2,4-triazolidine-3,5-dithiones either with E. utilis seedlings present for 7 days, with S. acutus cells, or using glutathione 5-transferase (GST) and glutathione (GSH). The phytotoxic activities of 4-aryl-1,2-tetram ethylene-1,2,4-triazolidine- 3,5-dithiones were stronger than those of 5-arylimino-3,4-tetram ethylene-1,3,4-thiadiazolidine- 2-thiones [cf. Sato, Y., et al., Z. Naturforsch. 49c, 49-56 (1994)].
Endogenous Gibberellins from Three East Asian Stenophora Species of the Genus Dioscorea (Yams)
Authors: Tanno Noriaki , Nakayama Masayoshi , Kurosawa Hiroshi , Wakatsuki Masahiro , Tanno Masahiro , Abe Mamoru , Okagami Nobuo , Yokota Takao 
Published: August 2018

Abstract
Exogenous gibberellin A3 (GA3; 30 μm) promoted shoot elongation of germinated seeds of Dioscorea nipponica, an East Asian species of a taxonomic section Stenophora of the genus Dioscorea (yams). Endogenous gibberellins (GAs) were analyzed by combined gas chromatography-mass spectrometry (GC-MS) from growing shoots of three East Asian Stenophora species. Gibberellin A4, GA12, GA 19, GA24 and GA53 were identified by Kovats retention indices and by full spectra of GC-MS from D. quinqueloba. Gibberellin A19, GA24 and GA53 were also identified from D. nipponica and D. septemloba. These results suggest that two separate biosynthetic pathways of GAs, early 13-hydroxylation and non-13-hydroxylation pathways are functioning in the growth of shoots of these thee species.
Iron(III) Complexes with Hydrogen Peroxide which Can Discriminate Two Reaction Types; Oxidation (H-Atom Abstraction) and Oxygenation Reaction
Authors: Nishida Yuzo , Ito Sayo 
Published: August 2018

Abstract
Iron(III)-NTA (nitrilotriacetic acid) solution shows high activity for oxidative degradation of 2′-deoxyribose in the presence of hydrogen peroxide, whereas its activity of Fe(III)-TFDA (2-aminomethyltetrahydrofuran-N,N-diacetic acid) is negligible under the same experimental conditions; however the latter solution exhibits abnormally higher reactivity for oxygenation reaction at 8-position of 2′-deoxyguanosine than other iron(III) chelates examined. These results suggest that oxidative degradation of deoxyribose and the oxygenation of deoxyguanosine are caused by a different iron(III)-peroxide species.
Cell Wall Pigment Formation of in vitro Cultures of the Liverwort Ricciocarpos natans
Authors: Kunz Siegmund , Becker Hans 
Published: August 2018

Abstract
The liverwort Ricciocarpos natans has been cultivated on Gamborg B5 medium with different levels of ammonium, nitrate, phosphate and sucrose. The formation of the cell wall pigments riccionidin A and B was shown to be dependent on the level of these nutrients as well as on the intensity of light. A decrease in nitrogen supply (mainly nitrate) induced the formation of both wall pigments, whereas phosphate and high levels of sucrose inhibited the pigment synthesis. Decreasing the illumination rate led to lower anthocyanidin contents. Dedifferentiated cultures also produced wall pigments, but their amount was much lower compared to differentiated cultures.
Thermodynamic and Spectroscopic Characterization of the Berenil and Pentamidine Complexes with the Dodecanucleotide d(CGCGATATCGCG)2
Authors: Schmitz Hans-Uwe , Hübner Wigand , Ackermann Theodor 
Published: August 2018

Abstract
The dodecanucleotide d(CGCGATATCGCG)2 was characterized by thermodynamic and UV-spectrophotometric measurements. A van’t Hoff enthalpy of ΔHuv
v.H. ~ - 190 kJ/mol was determined for the thermal transition using UV spectroscopy. This value was confirmed by differential scanning calorimetry (DSC). In addition we obtained the thermodynamic data ΔHDSC = -405.1 kJ/mol, ΔSDSC = -1290 J/mol·K and ΔGDSC = -53.2 kJ/mol for the helix to coil transition of the dodecanucleotide. The association of berenil and the oligonucleotide was accompanied with a stabilization of the host duplex (increase in Tm) and an increase in the van’t Hoff enthalpy. The berenil binding parameters (ΔΔHDSC = -32.6 kJ/mol, ΔΔSDSC = -72 J/mol·K and ΔΔGDSC = -11.1 kJ/mol) revealed significant differences compared to those of the pentamidine aggregation (ΔΔHDSC = -23.7 kJ/mol, ΔΔSDSC = -53 J/mol·K and ΔΔGDSC = -7.8 kJ/mol). The transition of the pure oligonucleotide was characterized by a substantial amount of intermediate states (σDSC = 0.43) which decreased significantly upon binding of the drugs (σDSC ~ 0.80). The structural features of the complexes were analyzed by FT-IR spectroscopy. From these experiments we conclude that the configurations in the berenil and pentamidine complexes are different.
Polyphenol and Alkaloid Changes in Glyphosate-Treated Tobacco Regenerants Selected for Herbicide Tolerance
Authors: Bankova Vassya St. , Handjieva Nedyalka V. , Djilianov Dimitar L. , Vassileva Zarka Y. , Bachvarova Rositsa I. , Atanasov Atanas I. , Stefanov Kamen L. , Popov Simeon S. 
Published: August 2018

Abstract
In vitro a one-step selection for glyphosate tolerance of two Bulgarian tobacco cultivars Zlatna Arda and Nevrokop A24 was carried out. After treatment with glyphosate of the control plants and their regenerants polyphenol and alkaloid changes were determined. A decrease in the polyphenol concentrations and an increase in the alkaloid concentrations were registered only for Zlatna Arda.
Flavipucine and Brunnescin, Two Antibiotics from Cultures of the Mycophilic Fungus Cladobotryum rubrobrunnescens
Authors: Wagner Christian , Anke Heidrun , Besla Helmut , Sterner Olov 
Published: August 2018

Abstract
Two antimicrobial metabolites were isolated from submerged cultures of Cladobotryum rubrobrunnescens, a mycophilic fungus growing on a Inocybe species. One of the compounds proved to be identical to flavipucine (2), an antibiotic previously isolated from Aspergillus flavipes (Casinovi et al., 1968) and from a Macrophoma species (Sassa T. and Onuma Y. (1983), Agric. Biol. Chem. 47, 1155-1157). The other metabolite, brunnescin (1), is a new tetrasubstituted furan derivative which exhibits antibacterial, antifungal and cytotoxic effects.
Mutants of the Cyanobacterium Anabaena variabilis Altered in Hydrogenase Activities
Authors: Mikheeva Lidia E. , Schmitzh Oliver , Shestakov Sergey V. , Bothe Hermann 
Published: August 2018

Abstract
Two mutants of the cyanobacterium Anabaena variabilis impaired in the utilization or formation of molecular hydrogen have been obtained by nitroso-guanidine mutagenesis. Cul­tures of both mutants did not show alterations in the growth characteristics or in the hetero­cysts frequency but evolved molecular hydrogen from nitrogenase with enhanced rates. Ac­tivity measurements in extracts showed that one mutant (PK84) did not perform Na2S2O4- dependent H2-formation and was, therefore, unable to express an active bidirectional hydro­genase. Both mutants (PK84, PK 17R) were characterized by lower activity of phenazine-methosulphate-dependent H2-uptake when extracts were assayed from younger cultures. In older cells, particularly when grown with nitrate in the medium , this H2-uptake activity was, how ever, enhanced. Both mutants are likely affected in regulatory hydrogenase genes. The mutant PK84 offers perspectives for potential applications in solar energy conversion programs.
Isolation and Partial Characterization of a Manganese Requiring ʟ-Arginine Metabolizing Enzyme Being Present in Photosystem II Complexes of Spinach and Tobacco
Authors: Gau Achim E. , Thole Hubert H. , Pistorius Elfriede K. 
Published: August 2018

Abstract
A low ʟ-arginine metabolizing enzyme (L-AME) activity leading to ornithine, urea and additional products not identified so far could be detected in photosystem II (PS II) membranes of spinach and of the chlorophyll deficient tobacco mutant Su/su. The detectable L-AME activity was very low in untreated PS II membranes, but increased significantly (about 10 fold) when the extrinsic peptides (psbO, P and Q gene products) were removed - suggesting that the L-AME is exposed at the lumen side of PS II. It was possible to isolate the detergent-solubilized protein from CaCl2-washed PS II membranes of spinach by a combination of anion and cation exchange columns. On the basis of SDS PAGE the protein was homogenous and had an apparent molecular mass of 7 kDa. N-terminal sequencing of the polypeptide gave a contiguous sequence of 20 amino acids showing no homologies to PS II polypeptides as yet sequenced. After chromatography of the L-AME on an anion exchange column at pH 9.5 (last purification step) a completely inactive enzyme was obtained. Maximal reactivation was achieved by dialyzing the protein against Hepes-NaOH buffer in the pH range of 6.5 to 7.5 containing 100 mᴍ chloride or sulfate (being the most effective anions). The L-AME activity was totally dependent on manganese added to the reaction mixture. Moreover, there were indications of a second cation binding site being more sequestered and requiring bound Ca2+ or Mn2+ for activity (Sr2+ was less effective and Mg2+ was ineffective). There are indications that the protein contains a redox active group - possibly an aminoacid- derived quinonoid (based on a redox cycling assay with glycine and nitroblue tetrazolium). The capability of this PS II associated protein to bind the cofactors of water oxidation and having a redox active group (preliminary results) suggests that this protein might be functional in photosynthetic water oxidation. This is further supported by the fact that the isolated L-AME has a low catalase activity
Plural Origins of the Molecular Homochirality in Our Biota
Authors: Dias Lins Roberto , Soares Thereza Amelia , Ferreira Ricardo 
Published: August 2018

Abstract
We describe results of computer simulation calculations of mixed and homochiral oligoribotides showing that it is possible to bind ʟ( D)-monomers at the term in al positions of chains built from D (L )-ribotides, but insertion at internal positions produces a large in stability of the chains. Coupled with aproposed new mechanism for the growth of these lin ear polymers in prebiotic conditions, our results imply that enantiomericcross-inhibition could have been bypassed to make all-D(ʟ) oligoribotidesdominant. We also show that racemic amino acids can form stable peptide β-strands, which rules out a similar origin for modern L -amino acids. Alternative schemes are proposed to account for the homochiralities of the amino acids and of other bio molecules.