bluuebunny/crossref_metadata_2025 huggingface dataset:
Two New Anthraquinones from Digitalis cariensis
Authors: Imre Sedat , Ertürk Sıdıka , Imre Zeliha
Published: August 2018

Two new minor anthraquinones, ω-hydroxydigitoemodin (1) and ω-hydroxyziganein-1-methyl ether (4), have been isolated from Digitalis cariensis. Their structures were elucidated on the basis of spectral analysis and 1 was also confirmed by synthesis.
Inhibition of State Transition and Light-Harvesting Complex II Phosphorylation-Mediated Changes in Excitation Energy Distribution in the Thylakoids of SANDOZ 9785-Treated Plants
Authors: Joshi Manoj K. , Mohanty Prasanna , Bose Salil
Published: August 2018

Thylakoids isolated from SAN 9785 (4-chloro-5-dimethylamino-2-phenyl-3(2H)-pyridazi-none)-treated pea plants showed an inhibition of “state transition” and the light-harvesting complex II (LHC II) phosphorylation-mediated changes in the energy distribution between photosystem II (PS II) and photosystem I (PS I) as measured by a decrease in PS II and an increase in PS I fluorescence yield. Interestingly, in these thylakoids the extent of phosphorylation-induced migration of light-harvesting complex (LHC II-P) to non-appressed mem­brane regions was only marginally inhibited. We propose that the suppression in the ability for “state transition” by SANDOZ 9785 (SAN 9785) treatment occurs due to a lack of effec­tive coupling of the migrated LHC II-P and PS I. Since we observed a decrease in the antenna size of PS I of the treated plants, the lack of effective coupling is attributed to this decrease in the antenna size of PS I.
Studies on Activation of H3 Histamine Receptor: A Mechanistic Model
Authors: Karpińska Grażyna , Mazurek Aleksander P.
Published: August 2018

The recognition and the activation mechanism of the H3 histamine receptor was studied based on quantum-chemical calculations. A mechanistic model proposed both for recognition and activation stage clarifies different properties of histamine and α-methylhistamine at the H3 receptor. Interaction with a hypothetical receptor sites leads to the opening of the intramolecular hydrogen bonding in histamine, whereas the α-methylhistamine remains in closed conformation.
Kinetic Studies of Protochlorophyllide Reduction in vitro in the Greening Mutant C-2A' of the Unicellular Green Alga Scenedesmus obliquus
Authors: Urbig Thomas , Knaust Rosemarie K. C , Schiller Hilmar , Sengera Horst
Published: August 2018

The NADPH-protochlorophyllide oxidoreductase, an enzyme catalysing the light-driven conversion of protochlorophyllide to chlorophyllide, was studied in the greening mutant C- 2A′ of the unicellular green alga Scenedesmus obliquus. Studies of the enzyme activity in

vitro showed strong dependence on the presence of glycerol and the detergent Triton X-100. Prerequisite for the formation of a photoactive enzyme complex is a sufficient preincubation time with the substrates PChlide and NADPH. A continuous assay system, reading the absorbance increase at the wavelength of chlorophyllide, was used to determine the kinetic constants. The Km value for NADPH is 4.2 μᴍ, the Vmax is 5.9 pmol · s-1. The Km and Vmax for protochlorophyllide are 0.19 μᴍ and 6.5 pmol · s-1, respectively. The pH-dependence of the reaction exhibits a broad maximum between pH 7-8.5 typically for an enzyme active during chloroplast development, when pH-changes might be expected.

The obtained kinetic data outline that the light dependent formation of chlorophyll in vivo is not limited by the substrates PChlide and NADPH, indicating that only light is the triggering factor in the very early greening process.
Accumulation and Biosynthesis of Solanapyrone Phytotoxins by Ascochyta rabiei
Authors: Benning Gregor , Barz Wolfgang
Published: August 2018

The biosynthesis of the phytotoxins solanapyrone A , B and C produced by the phytopathogenic fungus Ascochyta rabiei has been investigated. To optimize feeding conditons for the tracer experiments the growth of the fungus and the accumulation of the toxins in submers culture were determined. The accumulation kinetics revealed that formation of the toxins occurs in the stationary phase of the growth indicating that synthesis of solanapyrones follows a typical pattern of secondary metabolism. Incorporation experiments with sodium [1-14C]- and [2-13C]acetate were performed and the NMR-spectroscopically determined labelling pattern of the 13C-enriched solanapyrone A compound confirmed that the carbon skeleton of this compound is formed via the polyketide pathway. The biosynthetic route to solanapyrone B is discussed.
Europium- and Dysprosium-Ions as Probes for the Study of Calcium Binding Sites in Photosystem II
Authors: Burda K. , Strzałka K. , Schmid G. H.
Published: August 2018

Trivalent lanthanide cations are suitable probes for Ca2+-binding sites in photosystem II (PS II). PS II membranes prepared from Nicoticinci tabacum, intact and depleted of the extrinsic polypeptides were exposed to lanthanide ions (Dy3+ and Eu3+). Small concentrations of dysprosium and europium ions enhance oxygen evolution under short saturating flashes. Higher concentrations of the rare earth cations cause the release of the three extrinsic peptides (17, 23 and 33 kDa) and reduce O2 yield. The reactivation of the PS II membranes, thus depleted of the 33 kDa subunit, by Ca2+ ions is not possible. Comparing Eu3+ with Dy3+ in this effect shows that Eu3+ is more effective than Dy3+, because a lower Eu3+-concentration in comparison to that of Dy3+ inactivates O2-evolution. The differences between europium and dysprosium can be explained by their different ionic radius. Our results suggest the existence of two Ca-binding regions: one with a low affinity for calcium would be located on the contact surface of the 23 and 33 kDa proteins and the second one with a high affinity, should be located close to the Mn-cluster and to tyrosine-161 (Z ). The more tightly-bound calcium would be responsible for the activity of the PS II system.
Spatial Attractors in Aggregation Patterns of Dictyostelium discoideum
Authors: Steinbock Oliver , Müller Stefan C.
Published: August 2018

Chemotactic cell motion in aggregation patterns of the slime mould Dictyostelium discoideum is analyzed by a computerized cross-correlation method. In this excitable medium the movement of amoebae is selforganized by signals of cAMP that propagate as rotating spirals or expanding concentric circles (target patterns). A vortex-like rotation of cells is found close to the core of spiral waves, with a maximum velocity of 15 μm/min. Cell motion and spiral tip orbiting follow an opposite sense of rotation. The calculation of streamlines of the most probable trajectories reveals the exsitence of a closed curve (radius ≈ 130 μm) corresponding to the boundary of the spiral core. This spatial-limit cycle attracts the amoebae on rotational paths and leads to the formation of a cell-free disk in the centre of the pattern. In contrast, pacemakers of target patterns organize cell movement in a radial, star-shaped motion, leading directly to the formation of central mounds.
Flavonoid Aglycones from the Leaf Surfaces of Some Artemisia spp. (Compositae-Anthemideae)
Authors: Valant-Vetschera Karin M. , Wollenweber Eckhard
Published: August 2018

Several species of the large genus Artemisia have been analysed for the flavonoid aglycone composition of their leaf exudates. These species belong to different taxonomic groups within Artemisia. Flavone and flavonol aglycones were found as the major flavonoid constituents of the leaf exudates. Many of these compounds were 6-methoxylated, with additional substitutions at the 7-, 3′-and 4′-position of the molecule. In addition, 7,4′-substituted apigenin and luteolin derivatives and rarely also coumarin derivatives were encountered in some species. The observed substitution trends are in accordance with literature data. Taxonomic and eco­logical aspects are briefly discussed.
N-(3,4-Methylenedioxyphenyl)carbamates as Potent Flower-Inducing Compounds in Asparagus Seedlings as Well as Probes for Binding to Cytochrome P-450
Authors: Kusukawa Masashi , Iwamura Hajime
Published: August 2018

Abstract N-(3,4-Methylenedioxyphenyl)carbamates and related compounds were prepared to develop flower-inducing compounds in Asparagus seedlings and to assay binding to microsomal P-450 that has been postulated to be a possible triggering site for flowering. Some of the compounds had flower-inducing activity as effective as that of the previous potent com­ pounds. The microsomal P-450 formed a type I spectrum with a representative of the present compounds as well as with previous, structurally different classes of flower-inducing compounds; which are carbamate and amidine derivatives and piperonyl butoxide, a methylene-dioxy compound known as broad-spectrum P-450 inhibitor. Upon addition of NADPH , the spectra of these compounds changed to those with a peak centered at 460 nm, indicating that they all form a reactive, high affinity species to produce a complex with P-450. The target species of the compounds that induce flowering in asparagus seedlings was thought to be cytochrome P-450.
Notes: Determination of the Cytotoxicity of Rumex crispus during the Vegetation Period Using a Brine Shrimp Bioassay
Authors: Ömür L. , Kuruüzüm Ayşe
Published: August 2018

The percentage of anthraquinone glycosides in the roots of Rumex crispus L. (Polygonaceae) is significantly greater than in other parts of the plant. The roots of R. crispus in different vegetation stages were investigated with regard to anthraquinone glycoside content. Their toxicity towards shrimp were also tested during the vegetation period. The data showed that the percentage of anthraquinone glycosides as well as the toxic effect on the shrimp increased during the vegetation period.
1,2-Dihydroxymintlactone, a New Nematicidal Monoterpene Isolated from the Basidiomycete Cheimonophyllum candidissimum (Berk & Curt.) Sing
Authors: Stadler Marc , Fouron Jean-Yves , Sterner Olov , Anke Heidrun
Published: August 2018

1,2-Dihydroxymintlactone (1), a new monoterpene possessing nematicidal activity was isolated as a minor metabolite from the culture filtrate of the Basidiomycete Cheimonophyllum candidissimum , a fungus that previously has yielded nematicidal sesquiterpenes. The structure was determined by spectroscopic methods.
New Reactive Coenzyme Analogues for Affinity Labeling of NAD+ and NADP+ Dependent Dehydrogenases
Authors: Jeck Reinhard , Scholze Michael , Tischlich Anja , Woenckhaus Christoph , Zimmermann Jürgen
Published: August 2018

Abstract Reactive coenzyme analogues ω-(3-diazoniumpyridinium)alkyl adenosine diphosphate were prepared by reaction of ω-(3-aminopyridinium)alkyl adenosine diphosphate with nit­rous acid. In these compounds the nicotinamide ribose is substituted by hydrocarbon chains of varied lengths (n-ethyl to n-pentyl). The diazonium compounds are very unstable and decompose rapidly at room temperature. They show a better stability at 0 °C. L actate and alcohol dehydrogenase do not react with any of the analogues. Glyceraldehyde-3-phosphate dehydrogenase reacts rapidly with the diazonium pentyl compound. Decreasing the length of the alkyl chain significantly decreases the inactivation velocity. 3α,20β-Hydroxysteroid dehydrogenase reacts at 0 °C with the ethyl homologue and slowly with the propyl compound. The butyl-and pentyl analogues do not inactivate at 0 °C. Tests with 14C -labeled 2-(3-diazoniumpyridinium)ethyl adenosine diphosphate show that complete loss of enzyme activity results after incorporation of 2 moles of inactivator into 1 mole of tetrameric enzyme. 4-(3-Acetylpyridinium)butyl 2 ′-phospho-adenosine diphosphate, a structural analogue of NADP +, was prepared by condensation of adenosine-2,3-cyclophospho-5′-phosphomorpholidate with (3-acetylpyridinium)butyl phosphate, followed by hydrolysis of the cyclic phosphoric acid ester with 2 ′:3′-cyclonucleotide-3′-phosphodiesterase. Because of the redox potential (-315 mV) and the distance between the pyridinium and phosphate groups, this analogue is a hydrogen acceptor and its reduced form a hydrogen donor in tests with alcohol dehyd roge­nase from Thermoanaerobium brockii. The reduced form of the coenzyme analogue also is a hydrogen donor with glutathione reductase. With other NADP +-dependent dehydrogenases the com pound has been show n to be a competitive inhibitor against the natural coenzyme. The acetyl group reacts with bromine to form the bromoacetyl group. This reactive bromoacetyl analogue is a specific active-site directed irreversible inhibitor of isocitrate dehydrogenase.
Antioxidant Protection of Egg Lecithin Liposomes during Sonication
Authors: Gabrielska J. , Sarapuk J. , Przestalski S.
Published: August 2018

When model membranes are prepared by ultrasonic treatment of polyunsaturated phos­pholipids, radical production can induce a partial degradation of the polyunsaturated fatty acyl chains and the formation of lipid hydroperoxides. A suitable antioxidant employed dur­ing liposome preparation is able to protect them against lipid peroxidation. This work con­tains the results of studies on egg lecithin liposomes with incorporated antioxidants that were supposed to play the protective role mentioned. As it has been shown the antioxidant com pounds used ensured a 40-60% , i.e., satisfactory protection of liposomes after 30 min sonication. Possible practical applications are discussed.
Dihydropyoverdinsulfonsäuren - Zwischenstufen bei der Biogenese? / Dihydropyoverdin Sulfonic Acids - Intermediates in the Biogenesis?
Authors: Schröder H. , Taraz J. Adam. K. , Budzikiewicz H.
Published: August 2018

From the culture media of Pseudomonas aptata 4b and of Pseudomonas fluorescens ATCC 13525 5,6-dihydropyoverdin-7-sulfonic acids could be isolated. Their possible role in the biogenetic pathway leading to the pyoverdins will be discussed
Different Expression of Esterase Variants in Rat Hepatic and Hepatom a-Derived Cell Lines Detected by Electrophoresis
Authors: Afify Adel S. , Yamazaki Yoshimitsu , Kageyama Yu-ichi , Yusa Shiro , Ogawa Yoshikatsu , Okada Tomoko , Okuno Hiroaki
Published: August 2018

Esterases in nine rat hepatic and hepatoma-derived cell lines and normal rat liver homogenate were detected by polyacrylamide gel electrophoresis coupled with active staining with a-naphthyl acetate or butyrate as a substrate. The esterase band patterns of the non-cancerous and oncogene-transformed cell lines were alike, but different from those of hepatoma cell lines and normal rat liver homogenate. The former groups of cells might have completely lost the characteristics of rat liver parenchymal cells, or else they might have their origin at cells other than liver parenchyma. The esterase patterns of the hepatoma cell lines (e.g., McA-RH7777) and the normal rat liver highly resembled with each other, exemplifying the slight biochemical deviation of cancer from normal cells. However, two-dimensional electrophoretogram for the McA-RH7777 cell line showed a prominent esterase spot {p/ 6.0-Mr 110 kDa) that was lacking in the normal liver. This result indicates that there is invariably some change in esterase expression between the cancer cells and the normal liver cells
Cytochemical Localization of Guanylate and Adenylate Cyclase in Photoreceptor Cells of the Fly
Authors: Schraermeyer Ulrich , Stieve Hennig , Rack Michael
Published: August 2018

In photoreceptor cells of invertebrates light triggers an enzyme cascade in which the phos-phoinositide pathway is crucially involved. Likewise, there is growing evidence of an impor­ tant role of cyclic nucleotides, too. To localize these enzymes able to catalyze the formation of cGM P and cAMP, the spatial distribution of guanylate cyclase (EC 4.6.1.2) and adenylate cyclase (EC 4.6.1.1) was determined in photoreceptor cells of the fly. In photoreceptor cells of the blowfly (Calliphora erythrocephala), the electron dense reaction product of guanylate cyclase was found within the phototransducing region, the rhabdomeral microvilli and in the mitochondria. Staining was also observed throughout the cytoplasm of the microvilli. With the same cytochemical method, reaction product for adenylate cyclase was found on the tips of the photosensory membrane, and not in the cytoplasm of the rhabdomeral microvilli. The results presented here further argue for an important role of one or possibly two cyclic nucleotides in the photoreceptor cells, and possibly in the process of phototransduction of in­ vertebrates.
The Oxygen Sensitivity of Nitrogenase in Rhodobacter capsulatus: Repression and Inactivation
Authors: Klein Gesine , Jahn Andreas , Steindorf Astrid , Klipp Werner , Oelze Jürgen
Published: August 2018

In chemostat cultures of Rhodobacter capsulatus, growing aerobically in darkness, in situ nitrogen fixation occurred at significantly lower oxygen concentrations than the acetylene reduction activity of nitrogenase, as determined with samples from the culture under opti­ mum assay conditions. In contrast to nitrogenase of cultures growing diazotrophically at low oxygen, nitrogenase present in inactive form at the higher oxygen concentrations could not be activated to fix nitrogen by increasing i.) the energy supply by illuminating the cultures, ii.) the supply of cells with electron donor and iii.) cellular respiration. These results suggest that oxygen controls cellular nitrogen fixation directly rather than indirectly by interfering with the general metabolism. On this basis, the sensitivity toward oxygen of nif gene expression as well as of nitrogenase polypeptide accumulation was studied. The nifH promoter was active up to about 40% air saturation, exhibiting a biphasic sensitivity to oxygen, i.e. steep decreases in activity between 1 to 2% and between 10 to about 20% air saturation. A similar behaviour was observed with respect to cellular levels of both polypeptides of component 1 (Rc1) of nitrogenase, which were accumulated up to about 20% air saturation. Component 2 (Rc2) was less oxygen-sensitive than Rc1, its steady state level reached a maximum at 2% air saturation. A sudden increase in the ambient oxygen concentration, i. e. oxygen stress, revealed that, in vivo, nitrogenase was fairly stable against oxygen damage. Modification of Rc2 by ADP-ribosylation occurred under ammonium shock conditions, regardless of whether the cells fixed nitrogen or not. But it was not observed with cultures growing aerobically in the dark at steady state or under oxygen stress. Results obtained with mutant W107I of R. capsulatus lacking the modifying/demodifying enzymes supported the conclusion that modifi­ cation of Rc2 was not required for the inactivation of nitrogenase by oxygen.
Isolation, Characterization, and Substrate Specificity of the Plasma Membrane ATPase of the Halophilic Archaeon Haloferax volcanii
Authors: Steinert Kerstin , Bickel-Sandkötter Susann
Published: August 2018

Isolated membranes of the moderate halophilic bacterium Haloferax volcanii are able to hydrolyze ATP via an ATPase, which needs the presence of Mg2+ or Mn2+, high concentra­ tions of NaCl, a pH value of 9, and high temperatures with an optimum at 60 °C. We have not found any phosphatase activity in the preparations. We developed a purification method for the isolated enzyme with an enrichment factor of 90. SDS-gel electrophoresis of the partially purified enzyme of Haloferax volcanii showed putative ATPase subunits of 63, 51, 37, and 12 kDa. N-ethylmaleimide (NEM) a specific inhibitor for V-ATPases, which alkylates cysteines, inhibited the enzyme slightly. Binding of tritiated NEM to the isolated ATPase fractions resulted in labelling of the 63 and 51 kDa peptides. Using PCR with degenerate oligonucleotides, we could clone and sequence a gene cluster encoding the Aj part of the halophilic ATPase. The described genes are organized in an operon in the order D. C, E, B, A , named alphabetically according to their decreasing size. The deduced products of 64.5, 52, 38.7, 22, and 11.6 kDa confirm the results of the partial purification of the ATPase. Biochemical characterization of the Haloferax volcanii ATPase gave the following results: In presence of Mn2+ higher rates of ATP hydrolysis could be observed than in presence of Mg2+, but free manganese ions inhibited the enzyme activity of the ATPase. Calculation of the true concentrations of the complex between ATP and the respective divalent metal ion led to determination of Michaelis-Menten constants for ATP in the hydrolysis direction of 1 mм in presence of MgCl2 and 0.24 mм in presence of MnCl2. Sodium chloride concentrations in the molar range induce changes in K M by a factor of about 10. The enzyme is specific for ATP; other nucleotides including GTP and ADP are competitive inhibitors of ATP hy­ drolysis.
Toxicity of Palicourea marcgravii: Combined Effects of Fluoroacetate, N-methyltyramine and 2-Methyltetrahydro-β-carboline
Authors: Kemmerling Wilhelm
Published: August 2018

Feeding experiments carried out with cattle and horses could prove the toxic effects of P. marcgravii (Rubiaceae) in all cases. The typical symptoms of “sudden death”, however, are observed in ruminants only. This difference could not be explained so far. A part from fluoroacetate, two more substances also have influence the toxic effects and have been isolated from P. marcgravii for the first time: N-methyltyramine and 2-methyltetra-hydro-β-carboline (2-Me THBC). Structure elucidation of these compounds is mainly accom­ plished by 1H-NM R, 13C-NMR and MS techniques. Due to the small quantity of fluoroacetate (5.4 μg/g plant), the main toxic effect obviously lies in the two discovered substances. In contrast to the slow death of horses (monogastriers), the “sudden death syndrome” of cattle (ruminants) can be explained as a result of the higher resorbility of these two substances in the gastro-intestinal system. Given orally, both substances influence the monoamine oxidase type A (MAO-A): N-methyltyramine acts as a competitive substrate, and 2-Me THBC is one of the most effective MAO-A-inhibitors. Thus, the decomposition of the specific MAO-A-substrates noradrenaline and adrenaline as well as of N-methyltyramine itself is inhibited. The α-and β-receptors of the sympathetic system are stimulated more strongly, which leads to a drastic rise in blood pressure and thereby to a more rapid distribution of fluoroacetate in the body. This results in a reinforced input of fluoroacetate in the cells of especially active organs of the body (heart etc.). Thus, even smaller quantities of fluoroacetate are lethal.
Effect of Mg2+-ATP on Acetylcholinesterase of Electrophorus electricus (L.)
Authors: Matta A. Nery da , Silva C. B. , Hassón-Voloch A.
Published: August 2018

The effect of Mg2+-ATP on purified acetylcholinesterase (AChE) from electric tissue of Electrophorus electricus (L.) was studied. The enzymatic activities were measured with acetylcholine and acetylthiocholine as substrates. The kinetic parameters Vmax, Km and Hill coefficient (nH), for acetylcholine and acetylthiocholine were modified with Mg2+-ATP. It was shown that acetylcholinesterase presents an apparent activation at high concentration of substrates and an inhibition in the presence of Mg2+-ATP at low concentration of acetylcho line and acetylthiocholine. In addition, the data suggest that Mg2+-ATP induced an allosteric modulation of the acetylcholinesterase obtained from Electrophorus electricus (L.), and indi­cate an active adenosine triphosphate participation during cholinergic activity.
Xylaramide, a New Antifungal Compound, and Other Secondary Metabolites from Xylaria longipes
Authors: Schneider Gudrun , Anke Heidrun , Sterner Olov
Published: August 2018

Xylaramide (1), possessing potent antifungal activity towards Nematospora coryli and Saccharomyces cerevisiae, was isolated from the culture fluids of the wood-inhabiting ascomycete Xylaria longipes together with tyrosol (2), 2,5-bis(hydroxymethyl)furan (3) and 2-hexylidene- 3-methylsuccinic acid (4). The latter has been known as a Xylaria metabolite for many years. Compounds 2 and 3 have been previously reported from other fungi, whereas 1 is a new natural N -(2-phenylethenyl)-2-hydroxypropanamide. The isolation, structure determination and biological properties of xylaramide are described. The biological activities of the other compounds are included.
Bimodal Effect of Amphiphilic Biocide Concentrations on Fluidity of Lipid Membranes
Authors: Podolak Marian , Man Dariusz , Waga Stanislaw , Przestalski Stanislaw
Published: August 2018

Using the spin label method (ESR) it has been shown that biologically active, amphiphilic compounds (quaternary ammonium salts -AS) containing polar heads with single and double positive charge caused, at low concentrations, decrease fluidity of liposome membranes formed with egg yolk lecithin (EYL). At higher concentrations an increase in fluidity was observed. With compounds having a single positive charge minimum fluidity of membrane structure occurs in the range of 1 to 3%, with compounds containing double positive charge -in the range of 4 -6 % . That effect does not depend on polar head size and length of alkyl chains of the AS used. Analysis of the electrostatic interaction between positive charges and dipole system suggest that at low ion concentrations the binding energy of the system increases, while it decreases at high concentrations. For the model presented, maxi­mum of binding energy of the system occurs at 3% of positive monovalent ions and at 6% of positive divalent ions admixed.
Structure Elucidation of Azotobactin 87, Isolated from Azotobacter vinelandii ATCC 12837*, **
Authors: Schaffner E. M. , Hartmann R. , Taraz K. , Budzikiewicz H.
Published: August 2018

Chromopeptide siderophores (azotobactin 87-1 and -II) were isolated from an iron deficient culture medium of Azotobacter vinelandii ATCC 12837 (=DSM 87). Their structures were elu­ cidated by chemical degradation studies and spectroscopic methods, especially 2D-NMR-tech-niques. Total assignments of 1H-, 13C-, and 15N-resonances based on 2D-HOHAHA-, 1H/13C-HMQC-, 1H /13C-HMBC-, 1H /15N-HMQC/TOCSY-, and 1H/15N-HMBC-experiments are given as well as sequential information derived from 1H/1H-NOESY-, 1H /13C-HMBC-and 1H/ 13N-HMBC-experiments. Both Az 87-1 and Az 87-11 consist of a tetracyclic chromophore -(1S)8,9-dihydroxy-4-oxo-2,3,4,5-tetrahydro-1H,10cH-3a,5,10b-triazaacephenantrylene-1-carb-oxylic acid -and a decapeptide chain linked with the N-terminus to the carboxy group of the chromophore containing also modified, non-proteinogenic amino acids. The sequence L-Ser-D-Ser-L-Hse-Gly-D-threo-OHAsp-Hse-Hse-Hse-D-N5OH-N5-R-Hbu-Om-L-Hse was determined for Az 87-1, while Az 87-11 contains a C-terminal L-Hse-lactone instead. Iron is chelated by the catecholic group of the chromophore, the β-hydroxy aspartic acid, and the hydroxamate function formed by N5-hydroxyornithine and R-β-hydroxybutyric acid.
Effect of Amphiphilic Cationic Compounds on Calcium Ion Desorption from Lecithin Liposome Membranes. Kinetic Studies and Quantum Chemical Calculations
Authors: Kuczera Janina , Chojnacki Henryk , Kral Teresa E. , Przestalski Stanislaw
Published: August 2018

The effect of four amphiphilic cationic compounds that differ in their polar head properties on the kinetics of calcium ion desorption from unilamellar lecithin liposom e membranes has been studied. The compounds under investigation were: N-benzyl-N,N-dimethyl-N-tetradecy-lammonium chloride (BDTA), N-methyl-N-tetradecylmorpholinium bromide (MTM), N-methyl-N-dodecyloxym ethylenem orpholinium chloride (MDOM) and N,N,N-trimethyl-N-te-tradecylammonium bromide (TMTA). Kinetic constants were determined using the three-compartmental analysis for isotopic labels. For the above mentioned compounds electronic structure calculations were performed and point charges and dipole moments of the molecules determined by using quantum chemis­try methods. It was found that the rate of desorption increases with increasing concentration of the compounds studied, and effectiveness of the compounds follows the sequence: BDTA >MTM >TMTA >MDOM . For dipole moments the sequence obtained is somewhat different, namely: BDTA>MTM >MDOM >TMTA. Apparently, the differences in the effectiveness of action of the compounds in the calcium desorption process follow not only from the values of dipole moments of their polar heads but also from the values of point charges on some atoms and from steric properties.
Lipophilic Exudate Constituents of Some Rosaceae from the Southwestern USA
Authors: Wollenweber Eckhard , Henrich Birgit , Mann Karin , Roitman James N.
Published: August 2018

The lipophilic epicuticular material of four shrubby Rosaceae from the Southwestern USA has been studied. They all exhibit triterpene acids as major products. Adenostomci sparsifolium and Cowania mexicana var. glaber, the two species in which glandular structures and a lipophilic excretion are obvious, produce free flavonoid aglycones as well. In Adenostoma, most of these are very rare com pounds. Cowania exhibits some trivial and one rare flavone. In Cercocarpus montanus var. glaber and in Fallugia paradoxa the epicuticular material is devoid of flavonoids.
Species-Specificity of an Elicitor-Active Oligosaccharide, LN-3, to Leguminous Plants
Authors: Tai Akihiro , Kawazu Kazuyoshi , Kobayashi Akio
Published: August 2018

LN-3, a linear pyridylaminated hepta-β-glucoside previously found to show elicitor activity in alfalfa cotyledons, was examined for phytoalexin-inducing activity in pea epicotyl and bean cotyledon assays. LN-3 did not show (+)-pisatin-inducing activity in pea epicotyls. In the bean cotyledon assay, however, the (± )-kievitone content gradually increased with increasing LN- 3 concentration, and reached a maxim um (ca. 17 |ig/g fresh wt) at 100 μ/ml. Half-maximal elicitor activity was seen at ca. 16 μm . After three legumes, alfalfa, pea and bean, were treated with LN-3, the recovery of the rem aining LN-3 or its fragments was examined. Almost 100% of LN-3 or its fragments was recovered from the pea test solution; in contrast, recoveries from alfalfa and bean were only 63.8 and 38.1% , respectively. HPLC and LC-MS analyses of the recovered samples indicated that LN-3 was hydrolyzed to give mono- and/or diglucoside( s) in the alfalfa and the bean solutions, while in the pea experiment a small portion of LN-3 was hydrolyzed to give sugar fragments with different degrees of polymerization < 7.
Radiation-Induced Apoptosis in Thymocytes: pH Sensitization
Authors: Ojeda F. , Skardova I. , Guarda M.I. , Maldonado C. , Folch H.
Published: August 2018

Thymocytes were used as a model system to study the effect of microenvironmental pH changes on the radiation-induced apoptosis. We found that the sensitivity of thymocytes toward radiation induced apoptosis is increased by increasing the pH of the incubation me­dium. The major sensitivity change occurs between pH 7 and 8.

In a given cell suspension the results obtained where similar when the apoptosis evaluation was carried out either by counting the picnotic nuclei, or monitoring the fraction of apoptotic nuclei by flow cytometry; both methods show a radiosensitization when the pH value of incubation media rises from 7 to 8. These results may be important when “in vitro” experiments are performed with lymphoid cells, since changes in pH of the media may determine important changes in the results.
Painting of Human Chromosome 8 in Fifteen Minutes
Authors: Durm Markus , Hausmann Michael , Aldinger Klaus , Ludwig Horst , Cremer Christoph
Published: August 2018

The technique of chromosome-in-situ suppression (ClSS)-hybridization (chromosome painting) has now been well established. However, all standard protocols so far require long renaturation times (typically 12 hours and more). Here, we describe a new, extremely fast pro­tocol for chromosome painting using a commercially available, directly fluorescence labelled probe for chro­mosome 8. The hybridization conditions used omit separate preannealing procedures and denaturing chemical agents. The renaturation time required for chromosome painting was reduced to 15 minutes. In addition, most washing steps were eliminated. As a consequence, the entire painting procedure was feasible in less than half an hour.
Preparation of [14C]-Labelled 1,2,3,4,6-Penta-O-Galloyl-β-ᴅ-Glucose and Related Gallotannins
Authors: Rausch Hans , Gross Georg G.
Published: August 2018

[U -14C]-Labelled 1,2,3,4,6-penta-O-galloyl-β-ᴅ-glucose was prepared by photoassimilation of 14CO2 with leaves from staghorn sumac (Rhus typhina) in the presence of the herbicide glyphosate. Extracts of the plant material were partitioned against ethyl acetate and chromatographed on Sephadex LH-20, yielding a series of crude tri-to decagalloylglucoses. The pentagalloylglucose fraction among these was further purified by HPLC to >99% purity and a specific radioactivity of 130 kBq (3.5 μCi) per μmol. The ratio of the radioactivities in the glucose and galloyl moieties, respectively, suggested a uniform labelling pattern of the product.
A New Non-Radioactive Assay of Phytoene Desaturase to Evaluate Bleaching Herbicides
Authors: Sandmann Gerhard , Schneider Christian , Böger Peter
Published: August 2018

A non-radioactive cell-free assay was developed to quantitatively determine inhibition of plant-type phytoene desaturase by bleaching herbicides. An active desaturase was prepared from an appropriately cloned E. coli transformant. Another E. coli transformant was used to produce the required phytoene. Phytofluene and t-carotene, the products of the desaturase reaction, were either determined by HPLC or optical absorption spectra. Enzyme kinetics and inhibition data for the bleaching tetrazole herbicide WL110547 are presented as an example.
Antiulcerogenicity of the Flavonoid Fraction from Erica andevalensis Cabezudo-Rivera
Authors: Reyes M. , Martín C. , Lastra C. Alarcón de la , Trujillo J. , Toro M. V. , Ayuso M. J.
Published: August 2018

Investigations were carried out to determine the antiulcerogenicity of the flavonoid fraction (ethyl acetate extract) of Erica andevalensis Cabezudo-Rivera on gastric ulceration induced by different experimental models. Oral treatment with the ethyl acetate extract and the major flavonoid (myricetin 3-O-ᴅ-galactoside) were found to be effective to prevent gastric ulceration induced by cold-restraint stress in rats . Statistically significant ulcer index values with respect to the control group were observed. Mucus content was not increased although it was accompanied by an increase in proteins and hexosamines. In pyloric-ligated animals flavonoids showed a significant reduction in the number and severity of the ulcers. Under the same conditions acidity did not decrease with the flavonic extract and myricetin 3-O-ᴅ-galactoside significantly as compared to control. Gastric ulcers induced by oral administration of absolute ethanol were reduced by pretreatment with the flavonoid extract of doses from 125 to 250 mg/kg and the isolated flavonoid of 25 mg/kg p.o. However neither the flavonic extract nor the isolated flavonoid induced changes in the amount and glycoprotein content of gastric mucus.
Healing Process Induced by a Flavonic Fraction of Bidens aurea on Chronic Gastric Lesion in Rat. Role of Angiogenesis and Neutrophil Inhibition
Authors: Calero M. J. Martín , La Casa C. , Motilva V. , López A. , Lastra C. Alarcón de la
Published: August 2018

Absrtract The aim of this study was to elucidate the mechanism of the healing process mediated by the flavonic fraction of Bidens aurea on chronic gastric ulceration induced by 5% acetic acid in rats. The diethyl ether extract (125 and 62.5 mg kg- 1 body weight) was administered in a single doses, 7 and 14 days after provocation of lesions. Our results demonstrated that both doses significantly decreased the macro and microscopic ulcer index. Usually after 14-days treatment the lesions were found completely covered with regenerative epithelium and also an important proliferation of blood vessels was observed. Myeloperoxidase (MPO) activity was assayed and used as an index of leucocyte infiltration. Application of acetic acid produced a significant increase of this activity 7 days after induction of chronic injury. Administration of 125 mg kg -1 of the ether extract provoked a sharp reduction on the enzymatic activity at the same period. After 14 days, this decrease was higher with both doses (p<0.001). In addition, the macroscopic examination showed a drastic reduction of leucocyte infiltration in treated groups. These results suggest that the recovery of vascularization of the ulcerated area and the decrease of neutrophil infiltration are involved in the antiulcerogenic effect of the flavonoid fraction of Bidens aurea.
Changes in Epicuticular Flavonoids and Photosynthetic Pigments as a Plant Response to UV-B Radiation
Authors: Cuadra Pedro , Harborne Jeffrey B.
Published: August 2018

Treatment of Gnaphalium vira-vira plants with UV-B radiation caused changes in plant growth and in plant chemistry. The leaf surface contained two O-methylated flavones, araneol and 7-O-methylaraneol. HPLC analysis showed that 20 days of UV-B radiation increased the synthesis of 7-O-methylaraneol at the expense of araneol. Spectrophotometric analysis of the photosynthetic pigments showed that UV-B radiation also increases the pigment content in treated plants. Another U V alteration is epidermal hair damage, as observed in SEM pictures of treated leaves. This combination of physiological and phytochemical effects may be interpreted as a plant response to UV-B stress
Differential Metabolism of the Sulfonylurea Herbicide Prosulfuron (CGA-152005) by Plant Microsomes
Authors: Moreland Donald E. , Fleischmann Thomas J. , Corbin Frederick T. , McFarland Janis E.
Published: August 2018

Microsomes isolated from excised shoots of 3-day-old. dark grown, grain sorghum [Sorghum bicolor (L.) Moench, Funk G522DR and DK 41Y] and corn seedlings [Zea mays (L.), Pioneer 3245] metabolized the sulfonylurea herbicide prosulfuron (CGA-152005). Corn microsomes predominantly formed a single major metabolite that resulted from hydroxylation of the phenyl ring at the C5 position. However, sorghum microsomes formed two major metabolites in an approximate 1:1 ratio. One was the 5-hydroxyphenyl metabolite, whereas the second metabolite resulted from ö-demethylation at C4 of the triazine ring. Metabolite identity was established by mass spectrometry and co-chromatography with authentic standards. Metabolism in both corn and sorghum was greatly enhanced by pretreatment of the seed with naphthalic anhydride and by subirrigation with 2.5% ethanol 24 h prior to harvest. Metabolism required a reduced pyridine nucleotide and was affected by several cytochrome P450 monooxygenase inhibitors (carbon monoxide, tetcyclacis, piperonyl butoxide, 1 aminobenzotriazole, and SKF-525A). The inhibitors differentially affected metabolism of prosulfuron. Microsomal oxidations from both untreated and inducer-treated tissue responded similarly to the inhibitors. In exploratory studies, microsomes isolated from shoots of wheat [Triticum aestivum L., Pioneer 2548], barley [Hordeum vulgare L., Boone], oats [Avena sativa L., Southern States 76-30-P242] and rice [Oryza sativa L„ Gulfmont], and room ripened avocado [Persea americana, Mill., Hass] mesocarp tissue also primarily formed the 5-hydroxyphenyl metabolite. Titration of seven different avocado microsomal preparations with prosulfuron provided typical type I difference spectra from which an average binding constant (Ks) of 187 ± 35 μm was obtained
2,3-Dihydroxy Fatty Acids-Containing Waxes in Storks (C iconiidae)
Authors: Jacob Jürgen , Raab Gottfried
Published: August 2018

Uropygial gland secretions from five out of a total of seven species forming the genus Ciconia (family Ciconiidae; order Ciconiiformes) were found to consist of mixtures of monoester waxes, diester waxes, triester waxes, and triglycerides. Monoester waxes were composed of unbranched fatty acids and alcohols, whereas diester waxes derived from both 2- and 3-hydroxy fatty acids esterified with unbranched alcohols and fatty acids. Interestingly, triester waxes were also found deriving from either 2-hydroxy alkylmalonic acids or from erythro-2,3-dihydroxy fatty acids the latter of which have not yet been found in vertebrates so far. To compare the typical mass spectrometric fragmentation of this class of compounds erythro-2,3-dihydroxyhexadecanoic acid has been synthesized
The Effect Of Antioxidants On The Decomposition Of Methyl 13-Hydroperoxyoctadecadienoate
Authors: Alam Md Khorshed , Nakajima Shuhei , Baba Naomichi
Published: August 2018

Phenolic antioxidants such as butylated hydroxytoluene, a-tocopherol, eugenol, isoeugenol, sesamol and quercetin effectively prevented thermal decomposition of methyl 13-hydroperoxyoctadecadienoate in methanolic solutions. Ascorbic acid, however, was found to promote the decomposition and the acidic nature of the vitamin was suggested to be involved in the mechanism
Effects of Fraxetin on Glutathione Redox Status
Authors: Martín-Aragón Sagrario , Benedí Juana M. , Villar Angel M.
Published: August 2018

We have evaluated the effects of an oral treatment of mice with fraxetin (25 mg/kg for 30 days) on the glutathione system (GSH, GSSG, and GSSG/GSH ratio as stress index), glutathione reductase (GR) and glutathione peroxidase (GPx) in liver supernatants from male C57BL/6J mice (18-month old). A significant antioxidant effect in vivo was found under this treatment by a decrease in the GSSG/GSH ratio and an increased activity of GR compared with the control mice. GSSG rate and GSSG/GSH ratio were correlated with the decline of GPx activity. Our results of increased GR activity could be considered as a supercompensation in glutathione redox status that involves a decrease in the accumulation of GSSG, as well as, in GSSG /GSH ratio. Finally, we suggest that this possible mechanism of supercompensation could lead to an enhancement in the average life span.
Surface Lipids of the Silverfish (Lepisma saccharina L.)
Authors: Jacob Jürgen , Raab Gottfried , Hoppe Udo
Published: August 2018

Surface lipids obtained from the silverfish by short-term solvent extraction contain ali­ phatic hydrocarbons, monoester waxes, cholesteryl esters, triglycerides, free cholesterol, and free fatty acids. Together, cholesteryl esters and free cholesterol account for >30% of the total lipids.

As found for other arthropods living in aquatic or moist environments unsaturated homologues predominate among the acidic constituents.

The cuticular lipid composition o f silverfish resembles that of other more primitive arthropod forms such as stoneflies and dragonflies.
The Structure of Preen Gland Waxes from Pelecaniform Birds Containing 3,7-Dimethyloctan-1-ol -an Active Ingredient against Dermatophytes
Authors: Jacob Jürgen , Eigener Ulrich , Hoppe Udo
Published: August 2018

A biologically active principle has been isolated from the uropygial gland secretion of the gannet (Sula bassana) exhibiting growth inhibitory activity for Gram-positive bacteria, yeasts, moulds and, in particular, for dermatophytes.The feather lipids of this species consist of monoester waxes predominantly composed of 3,x-dimethylalkanols esterified with fatty acids belonging to homologous series of 2-and 3-methyl-, 2,x-and 3,x-dimethyl-as well as 2,x,y-and 3,x,y-trimethyl-substituted alkanoic acids. For chemosystematic reasons other pelecani­ form species (Pelecanus crispus, Pelecanus onocrotalus, Phaeton lepturus) and one gaviiform species (Gavia stellata) have also been analysed. The pattern of their preen wax constituents suggest to assume that the Pelecaniformes are polyphyletic with gannets and cormorants being closely related, whereas pelicans and tropic birds are different, both from the former and from each other. Pelicans resemble very much the grebes, while tropic birds seem to be more closely related to the charadriiform, alciform, and possibly to the gaviiform birds.
Tropane Alkaloids of Hyoscyamus boveanus, H. desertorum, H. muticus and H. albus from Egypt
Authors: El-Shazly Assem , Tei Andreas , Witte Ludger , El-Domiaty Mäher , Wink Michael
Published: August 2018

The alkaloid composition of Hyoscyam us boveanus, H. desertorum, H. muticus and H. albus was investigated by capillary GLC and GLC-mass spectrometry. Altogether 39 alka­loids of the tropane and pyrrolidine types were identified. Several alkaloids were found in the different species for the first time, e.g., 22 alkaloids in H. boveanus, 13 in H. desertorum, 24 in H. muticus and 4 in H. albus. 3β-Hyoscyamine, dehydrohyoscyamine, phyllalbine, 3α-phenylacetyltropane, phenylacetylscopine as well as phygrine and 2,3-diacetonyl-N-methyl-pyrrolidine are apparently new for the genus Hyoscyamus. Alkaloid profiles and alkaloid contents of flowers, fruits, leaves, stems and roots were determined and their chemoecological functions discussed.
Inhibition of Succinic Dehydrogenase and F0F1-ATP Synthase by 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic Acid (DIDS)
Authors: Bernardes Celene F. , Meyer-Fernandes Jose R. , Martins Orlando B. , Vercesi Anibal E.
Published: August 2018

This study shows that incubation of rat liver mitochondria in the presence of the thiol/ amino reagent 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DID S) is followed by inhibition of both succinate supported respiration and oxidative phosphorylation. Half-maximal inhibition of succinic dehydrogenase activity and succinate oxidation by mitochondria was attained at 55.3 and 60.8 μm DIDS, respectively. DIDS did inhibit the net ATP synthesis and ATP ⇔ [32P]Pi exchange reaction catalyzed by submitochondrial particles in a dose-dependent manner (Ki= 31.7 μm and Ki = 32.7 μm), respectively. The hydrolytic activities of uncoupled heart submitochondrial particles and purified F 1 -ATPase were also inhibited 50% by 31.9 and 20.9 μm DIDS, respectively.
Interaction of Lignans with Human Sex Hormone Binding Globulin (SHBG)
Authors: Schöttner Matthias , Ganßer Dietmar , Spitelle Gerhard
Published: August 2018

Lignans bind to sex hormone-binding globulin (SHBG ). The lignan with the highest binding affinity is (±)-3,4-divanillyltetrahydrofuran. In a double Stobbe condensation - without use of protecting groups - a wide variety of lignans with different substitution pattern in the aromatic and aliphatic part of the molecule was synthesized. These lignans were tested in a SHBG -binding assay which allowed to deduce the following relationship between structure and activity: 1) (±)-diastereoisomers are more active than meso compounds 2.) the 4-hydroxy- 3-methoxy (guajacyl) substitution pattern in the aromatic part is most effective 3.) the activity increases with the decline in polarity of the aliphatic part of the molecule.