bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of Chromenes and Benzofurans in the Genus Encelia (Asteraceae)
Authors: Proksch Peter , Proksch Margareta , Weck Waltraud , Rodriguez Eloy 
Published: August 2018

Abstract
Phytochemical and microscopial analysis of leaves and stems of various species of Encelia showed a strict correlation between the presence of resin ducts and the accumulation of benzopy­rans and benzofurans. Fluorescence microscopy of Encelia farinosa proved unambigously that these compounds are stored exclusivly in the resin ducts and the surrounding cells.
The Widespread Occurrence in Nature of Anthocyanins as Zwitterions
Authors: Harborne Jeffrey B. , Boardley Marian 
Published: August 2018

Abstract
An electrophoretic survey of anthocyanins in flowers of 81 species belonging to 27 plant families indicated that malonated or similarly substituted zwitterionic anthocyanins occur in half the sample. In particular, almost all species surveyed in the Compositae and the Labiatae were positive. The same results were also indicated by HPLC separations. Detailed examination of the anthocyanins of Dahlia variabilis and Plectranthus argentatus confirmed the presence of malonylation through glucose. It appears that anthocyanins substituted by aliphatic dicarboxylic acids may be widespread in the angiosperms.
Biflavonoids, Quinones and Xanthones as Rare Chemical Markers in the Family Iridaceae
Authors: Williams Christine A. , Harborne Jeffrey B. 
Published: August 2018

Abstract
Amentoflavone has been characterised from leaves of Patersonia glabrata. This is the first report of a biflavone in the Monocotyledoneae. The quinone plumbagin, a characteristic con­stituent of three dicotyledonous families, is now found to be a useful marker for the genus Aristea; it also occurs in two Sisyrinchium species and in Sparaxis tricolor. Mangiferin, a C-glucosylxan-thone known previously in the Iridaceae only from Crocus, Iris and Gynandriris has now been found in Eleutherine, Rigidella, Gelasine and Tigridia. results is discussed.
Action of Methylthiopyrimidine Experimental Herbicides as Diuron-Like Inhibitors of Photosynthesis
Authors: Ducruet Jean-M arc , Scalla René 
Published: August 2018

Abstract
Derivatives of 6-chloro-5-methylthiopyrimidines provide potent inhibitors of the photosynthe­tic electron flow, which act like Diuron on fluorescence induction kinetics and competitively displace it from its binding site. Structure-activity relationships show that, unlike triazines, ac­tivities of 2-or 4-alkylamino derivatives are restricted by steric hindrances. Decreases in inhibit­ory activities of these compounds observed in triazine-resistant chloroplasts are lower than de­creases reported for triazines themselves.
Inhibition of Photosynthetic Electron Transport by Halogenated 4-Hydroxy-pyridines
Authors: Trebst A. , Depka B. , Ridley S. M. , Hawkins A. F. 
Published: August 2018

Abstract
Herbicidal halogen substituted 4-hydroxypyridines are inhibitors of photosynthetic electron flow in isolated thylakoid membranes by interfering with the acceptor side of photosystem II. Tetrabromo-4-hydroxypyridine, the most active compound found, has a pI50-value of 7.6 in the inhibition of oxygen evolution in both the reduction of an acceptor of photosystem I and an acceptor of photosystem II. The new inhibitors displace both metribuzin and ioxynil from the membrane. The 4-hydroxypyridines, like ioxynil, have unimpaired inhibitor potency in Tristreated chloroplasts, whereas the DCMU-type family of herbicides does not. It is suggested that 4-hydroxypyridines are complementary to phenol-type inhibitors, and a common essential element is proposed.
The 4-hydroxypyridines do not inhibit photosystem I or non-cyclic electron flow through the cytochrome b/f complex. But they do have a second inhibition site in photosynthetic electron transport since they inhibit ferredoxin-catalyzed cyclic electron flow, indicating an antimycin-like property.
A comparison of the in vitro potency of the compounds with the in vivo potency shows no correlation. A major herbicidal mode of action of the group is related to the inhibition of carotenoid synthesis, and access to the chloroplast lamellae in vivo for inhibition of electron transport may be restricted.
γ-Radiolysis of 2′-Deoxyguanosine The Structure of the Malondialdehyde-Like Product
Authors: Langfinger Dieter , Sonntag Clemens von 
Published: August 2018

Abstract
In the -γradiolysis of N2O/O2-saturated solutions of 2′-deoxyguanosine, 2′-deoxyguanosine-5′-aldehyde has been identified as the major product (G = 0.27) which gives rise to a positive 2-thiobarbituric acid test usually associated with malondialdehyde or structurally closely related compounds. From experiments with tetranitromethane as oxidant instead of oxygen it is concluded that the major primary precursor is not the radical at C(5′) of the sugar moiety but a base radical. The relevance of these observations with respect to radiation-induced changes in DNA is discussed.
Inhibition of Bluelight-Induced, Flavin-Mediated Membraneous Redoxtransfer by Xenon
Authors: Schmidt Werner 
Published: August 2018

Abstract
Xenon as a potential triplet quencher is capable of in­hibiting bluelight-induced, flavin-mediated transport of redox-equivalents across lipid membranes. The experiments described are based on a model system developed recently. Ferricytochrome c as a potential electron acceptor is trap­ped in the lumen of unilamellar lipid vesicles, EDTA* as a potential electron donor added to the bulk volume and amphiphilic flavin as a mediator bound to the vesicle mem­brane. However, Under isotropic aqueous conditions the bluelight-driven electron transport chain comprising EDTA, flavin and Cyt c is not significantly affected by xenon. These data call for the reinterpretation of results obtained with xenon as potential inhibitor of phototropic curvature of grass coleoptiles. which were taken to suggest the flavin singlet as active species.
Photoaffinity Labeling of Spinach Thylakoids and Cytochrome b6/f-Complex by the Hydrophobic Reagent 3-(Trifluoromethyl)-3-(m-[125I]iodophenyl)-diazirine
Authors: Oettmeier Walter , Soli Hans-Joachim , Olschewski Ellen 
Published: August 2018

Abstract
In isolated spinach thylakoids the hydrophobic photo­reactive probe 3-(trifluoromethyl)-3-(m-[125I]iodophenyl-diazirine almost exclusively labels the photosystem I reac­tion center and the light-harvesting chlorophyll a/b protein. In isolated cytochrome b6/f-complex, all four components of the complex get labeled, but to a different extent. The amount of labeling in the protein components is correlated to the number of polypeptide segments embedded in the membrane system.
Vergleichende Untersuchungen zur Bildung und Akkumulation von ätherischem Öl in der intakten Pflanze und in Zellkulturen von Pimpinella anisum L. / Comparative Studies on the Production and Accumulation of Essential Oil in the W hole Plant and in the Cell Culture of Pimpinella anisum L
Authors: Reichling J. , Becker H. , Martin R. , Burkhardt G. 
Published: August 2018

Abstract
Comparative studies on the essential oil of the whole plant and callus-and suspension cultures of Pimpinella anisum L. were carried out. Both the whole organism and the cell cultures were shown for the first time to be similar in their constituents e.g. anethole, pseudoisoeugenol-(2-methyl-butyrate), epoxy-pseudoisoeugenol-(2-methyl-butyrate) and β-bisabolene. In difference to the plant, the callus-culture contained myristicine.
2-Hydroxy-Swietenin, ein neues Limonoid aus Swietenia mahagoni DC. / 2-Hydroxy-Swietenin, a New Limonoid from Swietenia mahagoni D C .
Authors: Daily Amir , Seligmann O. , Lotter H. , Wagner H. 
Published: August 2018

Abstract
From the seeds of Swietenia mahagoni two limonoids have been isolated and identified as swietenine and the hitherto not described methyl-2,3,6-trihydroxy-melia-C-8(30)-enate-3-tiglate (2-hydroxy-swietenine) by spectroscopic methods.
The Action of Saraca asoca Roxb. de Wilde Bark on the PGH2 Synthetase Enzyme Complex of the Sheep Vesicular Gland
Authors: Middelkoop T. B. , Labadie R. P. 
Published: August 2018

Abstract
Extracts of S. asoca bark and pure compounds isolated from the bark were tested for properties that might inhibit the conversion of arachidonic acid by the PGH2 synthetase. They were assayed spectrophotometrically with adjrenaline as cofactor. Methanol- and ethyl acetate extracts inhibited the conversion. The observed inhibition was confirmed in an oxygraphic assay. Two procyanidin dimers from the ethyl acetate extract showed enzyme catalyzed oxidation in our assay. The ether extract of the bark was also found to contain yet unknown substances which were capable of being oxidised by the PGH2 synthetase. The combined action of the components of the bark may explain the mode of action of the drug Asoka Aristha, the main ingredient of which is the bark of S. asoca. The drug is traditionally used in Sri Lanka to treat menorrhagia.
Vergleich verschiedener Immun-Dekorationsmethoden für die Rasterelektronenmikroskopie am Beispiel eines Protein-Antigens auf der Oberfläche der Hefe Candida albicans/ A Comparison of Decoration Techniques for the Demonstration of Immunocomplexes by Scanning Electron Microscopy: Labeling of a Protein Antigen on the Surface of the Yeast Candida albicans
Authors: Borg Margarete 
Published: August 2018

Abstract
The labeling of immunocomplexes for scanning electron microscopy (SEM) is a fairly new technique, and the various procedures, that have been proposed, have not yet been compared. Such comparative evaluation was performed with Candida protease as a target antigen. This secretory enzyme of the opportunistic yeast Candida albicans can be localized on the surface of fungal blastopores and mycelia, both after growth in proteinaceous medium and upon infection of murine peritoneal macrophages. The presence of the protease antigen was confirmed by immunofluorescence and by immunoperoxidase-light microscopy.
The decoration of protease - anti protease complexes for SEM was attempted with colloids derived from the immunoperoxidase reaction, by the immunogold technique, and by antibodies linked to beads of synthetic polymers (polystyrene, polymethacrylate, polyacrolein). In addition, inactivated Staphylococcus aureus was used, which binds to antibodies through its protein-A.
The high resolution by SEM of surface structures was matched only by the colloid based decoration techniques. All conjugates with beads suffered from inconsistent binding, which did not correspond with the distribution of the surface antigen. The comparatively best result with beads was obtained with polystyrene (Latex). Colloid based techniques in addition allow for critical point drying, which cannot be applied to synthetic beads in the usual manner.
Isotopic Effect on the Kinetic of Thermal Denaturation of Ceruloplasmin
Authors: Sportelli L. , Desideri A. , Campaniello A. 
Published: August 2018

Abstract
The kinetics of thermal denaturation of ceruloplasmin in water and in water with different percentage of D20 in the temperature range 25 - 85 °C, following the optical density change of the 610 nm charge transfer band of the protein has been investigated.
A temperature Tt ≃ 65 °C above which an irreversible denaturation process of the protein active site takes place has been found.
The kinetics of the denaturation process of the protein are fitted by two first order reactions, which have been assigned to a different thermal denaturation behaviour of the two Cu2+ type I sites existing in the protein. Addition of D2O to the protein solution affects the two kinetics in a different way, i.e. the rate of one of them is increased whilst that of the other is decreased.
The different effect of D2O on the kinetics of disruption of the two copper sites is discussed in terms of different location and degree of hydrophobicity of the two Cu2+ type I sites.
Acetohydroxyacid Synthase Inhibitors: N-Phthalyl-ʟ-valine Anilide and Related Compounds
Authors: Huppatz John L. , Casida John E. 
Published: August 2018

Abstract
The potency of ʟ-valine as an inhibitor of Zea mays acetohydroxyacid synthase (AHAS) is increased more than 80110-fold on conversion to its N-phthalyl anilide derivative which is active at 2 µᴍ. The ᴅ-valine, α-aminobutyric acid, isoleucine and phenylalanine analogs are 11- to 43-fold less potent, and similar N-phthalyl anilide derivatives of other branched-chain amino acids are essentially inactive. Full potency is retained on replacing the phthalimide moiety of the valine anilide with cyclohexane-1,2-dicarboximide or 1-cyclohexene-1.2-dicarboximide groups and partial activity with 4-cyclohexene-1,2-dicarboximide and methyl- or dimethylmaleimide groups. Inhibition of the enzyme and of root growth by the valine derivatives may result from binding at or near the site involved in feedback control of AHAS by ʟ-valine.
The Kinetics of the Reaction of Thiocyanate and Nitrite Ions with Orconectes limosus Oxyhemocyanin
Authors: Gondko Roman , Serafin Eligiusz , Mazur Janusz , Jeżowska-Trzebiatowska Bogusława , Jezierski Adam 
Published: August 2018

Abstract
The time course of the reaction of oxyhemocyanin from the arthropod Orconectes limosus with SCN− and NO2
− was investigated. After addition of one of these anions to oxyhemocyanin solu­tion an exponential decay of A340 was found, indicating a removal of oxygen from the active site. The order of reaction with respect to ligand was about 3 for thiocyanate and about 1 for nitrite. On this basis, a possible arrangement of ligands in the active site has been proposed. The final product of reaction with SCN− yielded a mononuclear copper EPR spectrum while the reaction product with NO2
− gave a characteristic spectrum of two coupled Cu2+ ions. It was possible to remove the ligands from the active site by dialysis. The reaction patterns showed distinct changes in a narrow pH range, 5.3-6.5. A possible effect of structural alterations of the protein moiety on the course of the reaction of oxyhemocyanin with ligands is suggested.
Partial Purification and Some Properties of 1-Sinapoylglucose: Choline Sinapoyltransferase ("Sinapine Synthase") from Seeds of Raphanus sativus L. and Sinapis alba L.
Authors: Gräwe Walter , Strack Dieter 
Published: August 2018

Abstract
Hydroxycinnamoyltransferases which catalyze the formation of O-sinapoylcholine (sinapine) using 1-0-sinapoyl-β-ᴅ-glucose as acyl donor have been isolated from seeds of radish (Raphanus sativus L. var. sativus) and mustard (Sinapis alba L.) and purified 420-and 293-fold, respectively. The enzymes (“sinapine synthase”) had apparent molecular weights of about 60,000 daltons and showed highest activities at pH 7.2 and 7.6, respectively, at 45 °C with apparent energies of activation at 53 kJ mol-1. There were no requirements for divalent cations or sulfhydryl reagents. The apparent Km’s of the radish and mustard enzymes were 0.48 and 0.71 mᴍ for 1-sinapoylglucose and 5.3 and 6.5 mᴍ for choline, respectively. The ratios of the Vmax/Km values for 1-sinapoyl-1-feruloyl- and 1-p-coumaroylflucose were found to be 100:19:19 (radish) and 100:20:29 (mustard). 6-0-Sinapoylglucose, 3-0-sinapoylfructose, 1-0-benzoyl- and 1-0-galloylglucose were not accepted as donors.
Inhibition of Phenylalanine Ammonia-Lyase in vitro and in vivo by (1-Amino-2-phenylethyl)phosphonic Acid, the Phosphonic Analogue of Phenylalanine
Authors: Laber Bernd , Kiltz Hans-Herrmann , Amrhein Nikolaus 
Published: August 2018

Abstract
The phosphonic analogue of ʟ-phenylalanine, (R)-(1-amino-2-phenylethyl)phosphonic acid (APEP), inhibits buckwheat phenylalanine ammonia-lyase (PAL) competitively with a Ki value of 1.5 μM. The Ki value for the (S)-enantiomer is 11.6 μM. The corresponding values for the enantiomers of the phosphonous analogue are 35 and 205 μm , respectively. APEP inhibits the light-induced synthesis of anthocyanin in hypocotyls of etiolated buckwheat seedlings and causes a specific increase in the endogenous phenylalanine concentration in buckwheat hypocotyls as well as other plant tissues. Kohlrabi seedlings develop normally in the presence of APEP, while their anthocyanin content is greatly reduced. These results indicate that APEP inhibits PAL in vivo.
Tyrosine Biosynthesis in Sorghum bicolor: Characteristics of Prephenate Aminotransferase
Authors: Siehl Daniel L. , Connelly James A. , Conn Eric E. 
Published: August 2018

Abstract
A stable activity which transfers the amino group from glutamate to prephenate was extracted from 4-day old etiolated shoots of sorghum. The activity was retained on DEAE cellulose and eluted as a single peak. Prephenate aminotransferase co-eluted with a very abundant α-ketoglutarate: aspartate aminotransferase, but heating at 70 °C resulted in loss of α-ketoglutarate: aspar­tate activity with nearly full retention of prephenate: glutamate aminotransferase activity. The heated enzyme displayed high affinity and specificity for prephenate. Among 7 donors tested, only glutamate, and aspartate at less than 20% the rate with glutamate, supported prephenate aminotransferase activity. In the reverse direction, a reaction rate comparable to that in the forward direction was unchanged as the concentration of α-ketoglutarate was reduced from 1.0 to 0.09 mᴍ. The apparent Km for arogenate was 0.8 mᴍ. The forward reaction was unaffected by the inclusion of tyrosine, phenylalanine or tryptophan. Together with the discovery of arogenate dehydrogenase in sorghum [3], these data indicate that, in the sorghum plant, tyrosine derives from prephenate by transamination and aromatization. rather than the reverse sequence.
Flavonoids and Terpenoids from the Exudates of Some Baccharis Species
Authors: Wollenweber Eckhard , Schober Ingrid , Dostal Pia , Hradetzky Dagmar , Arriaga-Giner Francisco J. , Yatskievych George 
Published: August 2018

Abstract
Seven species of the genus Baccharis have been analyzed for flavonoid aglycones. Many known methylated flavones, flavonols and flavanones were identified. From B. sarothroides, two novel flavonols were isolated and elucidated as 5,7,4′-trihydroxy-3,6,8-trimethoxyflavone and its methyl ether, 5,4′-dihydroxy-3,6,7,8-tetramethoxyflavone. Previous literature reports on flavonoids in Baccharis are summarized and their distribution and external occurrence is discussed. One novel diterpene and one rare triterpene were found in the terpenoid fractions that constitute most of the exudate material in these and other Compositae.
Transformation-Related Cellular Protein p53: Increased Level in Untransformed Rat Cells Following Treatment with the Tumorpromoter, Tetradecanoylphorbol-Acetate
Authors: Hebei Michael , Brandner Gerhard , Hochkeppel Heinz K. , Braun Dietmar G. 
Published: August 2018

Abstract
12-O-Tetradecanoylphorbol-13-acetate (TPA, 100 ng ml-1), a tumor promoting phorbol ester, is able to induce enhanced levels of the transformation-associated cellular antigen p53 in normal rat2 cells which had not been previously initiated by a carcinogen. p53 was estimated in ethanolfixed treated cells on microtiter plates with ELISA using the monoclonal antibody Pab 1620 [EMBO J. 7, 1485, (1984)]. Induction of p53 was confirmed by immunoblotting. This effect of TPA is an additional phenotypic characteristic of tumor cells which can be induced by TPA in untransformed rodent cells.
Glykosphingolipid-Analyse von menschlichen myeloischen Leukämien / Glycosphingolipid Analysis of Human Myeloid Leukemias
Authors: Kniep Bernhard , Mühlradt Peter F. 
Published: August 2018

Abstract
Neutral glycosphingolipids of human myeloid leukemia cells in different differentiation stages from nine patients were analyzed by high performance liquid chromatography. All cells contained ceramide monohexoside, lactosylceramide and neutral glycosphingolipids of the lacto-series. However, some of the leukemic cells contained neutral glycosphingolipids of the globo-series. Especially myelomonocytic cells (French-American-British or FAB classification M4) and poorly differentiated cells (FAB MO and M1) were found to contain globo glycosphingolipids. On myeloblast cells, (FAB M2), globo glycosphingolipids were missing or present only in very low amounts. It seemed, therefore, that on myeloid leukemic cells the glycosphingolipid composition may be dependent on their differentiation stage.
Metabolism of the Plant Growth Regulator (E)-[3H]2-Ethylhex-2-enoic Acid in Hordeum vulgare
Authors: Schneider Bernd , Schütte Horst-Robert , Preiss Alfred 
Published: August 2018

The metabolism of (E)-[3H]2-ethylhex-2-enoic acid (EHA) was studied in excised seedlings of barley (Hordeum vulgare). It was rapidly taken up from the nutrient medium. The metabolites, isolated by extraction with methanol, separated and purified by TLC and HPLC, were identified by enzymatic, chemical, and spectrometric methods, especially 1H-NMR spectroscopy.
The time course of metabolism during 6 , 12, 24, 48, and 72 h is presented, indicating interconversation reactions. A rapid conjugation with glucose was observed, decreasing in concentration again after longer time periods in favour of disaccharide esters, higher conjugates, and a hydroxylation product which was present in free and conjugated form.
Chemical Investigations of Tropical Medicinal Plants, XXI [1] Long Chain Alkyl Esters of Ferulic and p-Coumaric Acid from Bauhinia manca
Authors: Achenbach Hans , Stöcker Markus , Constenla Manuel A. 
Published: August 2018

Abstract
17 Esters of ferulic acid and p-coum ric acid were isolated from the stem extract of Bauhinia manca ; the alcohol components range from C22H45 to C28H57.
Genetic and Biochemical Studies on the Conversion of Dihydroflavonols to Flavonols in Flowers of Petunia hybrida
Authors: Forkmann G. , Vlaming P. de , Spribille R. , Wiering H. , Schram A. W. 
Published: August 2018

Abstract
Soluble enzyme preparations from flower buds of Petunia hybrida catalyzed the conversion of dihydroflavonols to flavonols. Dihydrokaempferol and dihydroquercetin were readily converted to the respective flavonols, whereas dihydromyricetin was a poor substrate. The reaction required 2-oxoglutarate, ascorbate and Fe2+ as cofactors and had a pH optimum at about 6.5. In the presence of the dominant allele Fl, high enzyme activity for flavonol formation was found, whereas in enzyme preparations from flower buds of recessive genotypes (fl/fl) only low enzyme activity could be observed. A substantial correlation was found between enzyme activity for flavonol formation and the flavonol content of buds and flowers during development.
Volatiles from Liquid Cultures of Lentinellus cochleatus (Basidiomycotina)
Authors: Hanssen Hans-Peter , Abraham Wolf-Rainer 
Published: August 2018

Abstract
The basidiomycete Lentinellus cochleatus CBS 201.47 was cultivated on a defined synthetic liquid culture medium containing glucose (2%), asparagine (0.15%), malt extract (0.2%), and mineral salts. 12 weeks old cultures produced a “sweet” odour with an anise-or cinnamon-like note. 3 major volatiles could be identified from the steam distillates by their GC/MS-and 1H NMR data. Predominant constituents were the acyclic sesquiterpene alcohols trans-nerolidol (41.4%) and fokienol (14.8%). 2,2-Dimethyl-6-formylchromene (6.1%) is described for the first time as a natural product. Besides these, 15 minor constituents could be identified or chemically charac­terized, respectively, the majority of them being sesquiterpene hydrocarbons and alcohols.
A Simple and Rapid Method for Isolation of 124 kDa Oat Phytochrome
Authors: Grimm Rudolf , Rüdiger Wolfhart 
Published: August 2018

Abstract
Native (124 kDa) phytochrome has been isolated from etiolated oat seedlings in 25% yield. The procedure includes only one chromatographic step namely a hydroxylapatite column, besides several centrifugation steps. Large scale preparations with 3 kg of fresh tissue are completed within 16 h. The purity of isolated phytochrome is as good as or even better than that of previous preparations as deduced from SDS gelelectrophoresis and from the absorbance ratio A667 / A280 = 0.99