bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Interactions of Quinidine with Phospholipid Bilayers
Authors: Suwalsky M. , Villena F. , Bagnara M. , Sotomayor C. P. 
Published: August 2018

Abstract
Quinidine (QUIN) is one of the most important and efficient antiarrhythmic drugs (AAD). It belongs to class I. which are the drugs that exert their action at the level of the sodium channels in the membrane of the myocard. Several hypotheses support the idea that the molecular mechanism of action of the AAD is via nonspecific interactions with phospholipids sited in the neighborhood of the channels. In order to probe the validity of these hypotheses, QUIN was made to interact with the phospholipids dimyristoylphosphadidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE). These interactions were performed in a hydrophobic and a hydrophilic medium under a wide range of molar ratios. The resulting products were analyzed by X-ray diffraction. QUIN solutions were also made to interact with DMPC liposomes, which were studied by fluorescent spectroscopy. Finally, human erythrocytes which were incubated with QUIN solutions were observed by scanning electron microscopy. The results of these experiments proved that QUIN indeed interacted with phos­pholipid bilayers.
Membrane Association of the Rieske Iron-Sulfur Protein
Authors: Szczepaniak Andrzej , Frank Karin , Rybka Jacek 
Published: August 2018

Abstract
The mode of membrane attachment of the Rieske iron -sulfur proteins from cytochrome b6ƒ complex of pea thylakoids and from cytochrome bc1 complex of yeast mitochondria has been studied using biochemical approaches.
The relative sensitivity of the Rieske protein to trypsin in the thylakoid membrane shows that all trypsin sites of the Rieske protein are on the lumen side of the thylakoid membrane. In contrast to cytochrome / the chloroplast Rieske protein was extracted from thylakoids using chaotropic agents (NaSCN, urea), an alkaline pH and relatively low concentrations of Trinon X-100. The cytochrome bc1 complex Rieske protein from mitochondrial membranes of yeast was also released by NaSCN and alkaline treatment.
The results presented here led us to the conclusion, that the mitochondrial and chloroplast Rieske proteins are extrinsic and that their association with the rest of the complex involves hydrophobic interactions.
Antioxidant Profile of Mono-and Dihydroxylated Flavone Derivatives in Free Radical Generating Systems
Authors: Montesinos María Carmen , Ubeda Amalia , Terencio María Carmen , Payá Miguel , Alcaraz María José 
Published: August 2018

Abstract
A number of free radical generating systems were used to investigate the antioxidant properties and structure-activity relationships of a series of monohydroxylated and dihydrox­ylated flavones. Ortho-dihydroxylated flavones showed the highest inhibitory activity on en­ zymic and non-enzymic microsomal lipid peroxidation as well as on peroxyl radical scaveng­ing. Most flavones were weak scavengers of hydroxyl radical, while ortho-dihydroxylated flavones interacted with superoxide anion generated by an enzymic system or by human neutrophils. This series of compounds did not exert cytotoxic effects on these cells. Scaveng­ing of superoxide and peroxyl radicals may determ ine the antioxidant properties of these active flavones.
Distribution and Stereochemistry of Hydroxycinnamoylmalic Acids and of Free Malic Acids in Papaveraceae and Fumariaceae
Authors: Boegge Sabine C. , Nahrstedt Adolf , Linscheid Michael , Nigge Walter 
Published: August 2018

Abstract
The distribution of hydroxycinnamoylmalic acids (HCM acids) in 25 species and 2 subspecies of Papaveraceae and Fumariaceae representing 14 genera was investigated by HPLC and subsequent diode array detection (DAD). In case of similar chromatographic and UV-spectrometric behavior of HCM acids and other hydroxycinnamic acid derivatives liquid chromatography-thermospray/mass spectrometry (LC-TSP/MS) was used for positive identification. Ten of the species were found to contain caffeoyl-, p-coumaroyl-. and feruloylmalic acid whereas Chelidonium majus only showed the presence of caffeoylmalic acid. Sinapoylmalic acid could not be detected. The quantitative determ ination by HPLC at 330 nm yielded the highest content of caffeoylmalic acid for Fumciria officinalis and F. capreolata, and the lowest for Chelidonium majus. Isolated HCM acids showed positive optical rotation for members of the Papaveraceae and negative values for m em bers of the Fum ariaceae. This points to an esterification of hydroxycinnam ic acids with (-)-ʟ -malic acid for the Papaveraceae and with (+)-ᴅ-malic acid for the Fumariaceae. For plants containing HCM acids the contents of free l - and ᴅ-malic acid w ere determ ined enzym atically Yields of ʟ-malic acid were higher for Papaveraceae than for Fum ariaceae; ᴅ-malic acid was detectable only in traces for all investigated species. The Fum ariaceae showed a ca. 1:1 relationship between free ʟ-malate and esterified ᴅ-malate. This suggests an enzym atic racem ization of the original ʟ-malate and a subsequent esterification of the intermediate ᴅ-malate with hydroxycinnamic acids
Genes Leave Their Characteristic Marks on the Melting Profile of Plasmid DNAs
Authors: Zubrzycki Igor Z. , Klump Horst H. 
Published: August 2018

Abstract
High resolution melting profiles of four linearised plasmids (pUC9, pGV403, pHP2, and pBR322) were recorded by means of UV absorbance vs. teperature scaning. The set of transitions obtained for each plasmid are compared to each another and to the transitions obtained for their excised particular antibiotica resistance gene. It can be shown that each gene leaves a charactersitic mark on the melting profile of its parental plasmid
Cooperative Binding of the Organophosphate Paraoxon to the (Na+ + K+)-ATPase
Authors: Blasiak Janusz 
Published: August 2018

Abstract
Paraoxon. the main active metabolite of the organophosphorus insecticide parathion. exerted a dose-dependent inhibitory effect on the activity of pig kidney (Na+ + K+)-ATPase contained in microsomal fraction and purified from it. Substrate kinetics studies revealed the existence of two active sites with high and low affinity to ATP. The Dixon analysis of the mode of the inhibition indicated its noncompetitive character. The purified enzyme was more affected than enzyme contained in the microsomal fraction. The inhibition constant K, ranged from 73 to 246 μm depending on the type of preparation. The Hill coefficient (n) fulfilled the relationship 1<n<3. These properties of the interaction suggest the cooperative binding of paraoxon to the enzyme. An indirect mechanism of the interaction was proposed: paraoxon could inhibit the activity of the (N a+ + K+)-ATPase by excluding the enzyme protein from its normal lipid milieu
Bioactive Alkaloids from the Tropical Marine Sponge Axinella carteri
Authors: Supriyono A. , Schwarz B. , Wray V. , Witte L. , Müller W. E. G. , Soest R. van , Sumaryono W. , Proksch P. 
Published: August 2018

Abstract
Analysis of the tropical marine sponge Axinella carteri afforded six unusual alkaloids, including the new brominated guanidine derivative 3-bromo-hymenialdisine. The structure elucidation of the new alkaloid is described. The alkaloid patterns of sponges collected in Indonesia or in the Philippines were shown to be qualitatively identical suggesting de novo synthesis by the sponge or by endosymbiontic microorganisms rather than uptake by filterfeeding. All alkaloids were screened for insecticidal activity as well as for cytotoxicity. The guanidine alkaloids hymenialdisine and debromohymenialdisine exhibited insecticidal activity towards neonate larvae of the polyphagous pest insect Spodoptera littoralis (LD50s of 88 and 125 ppm, respectively), when incorporated into artificial diet and offered to the larvae in a chronic feeding bioassay. The remaining alkaloids, including the new compound, were inactive in this bioassay. Cytotoxicity was studied in vitro using L5178y mouse lymphoma cells. Debromohymenialdisine was again the most active compound (ED50 1.8 μg/ml) followed by hymenialdisine and 3-bromohymenialdisine, which were essentially equitoxic and exhibited ED50s of 3.9 μg/ml in both cases. The remaining alkaloids were inactive against this cell line
Photosynthetic Characteristics of Three Strains of Cyanobacteria Grown under Low-or High-C02 Conditions
Authors: Miyachi Shigetoh , Bürger Joachim , Kotzabasis Kiriakos , Thielmann Jens , Senger Horst 
Published: August 2018

Abstract
Quantum requirements of photosynthetic oxygen evolution at 679 nm, fluorescence emis­sion spectra at liquid nitrogen temperature (77 K) and fluorescence induction kinetics in the presence of DCM U, were measured in the cyanobacteria Anabaena variabilis M3, Anabaena variabilis ATCC 29413 and A nacystis nidulans R2, each grown under low-or high-CO2 conditions. Low -CO2 grown cells of the cyanobacteria showed a higher quantum requirement of photosynthetic oxygen evolution and a higher ratio o F710-740 to F680-700 fluorescence and a lower variable fluorescence in the presence of DCMU than high-CO2 grown cells. These findings indicate a change in excitation energy distribution in favour of photosystem I. The result might be an enhancement in ATP formation caused by cyclic electron flow which in turn provokes dissolved inorganic carbon (DIC) accumulation in these low-CO2 grown cells.
Phenolic Compounds as a Tool of Bioindication for Novel Forest Decline at Numerous Spruce Tree Sites in Germany
Authors: Richter Christine M. , Eis Ulrich , Wild Aloysius 
Published: August 2018

Abstract
Within a project that applied biochemical criteria to the diagnosis of damage to Norway spruce, 43 sites in western and eastern Germany showing only moderate tree damage were screened for the amounts of methanol soluble phenolic compounds in spruce needles. The concentrations of most of the main compounds-especially catechin-positively correlated with needle loss and the altitude of the site. It was also found that it is necessary to differenti­ate between trees younger and older than 60 years of age. The correlations between the increase of the phenolic compounds studied and the needle loss or the damage class are stronger in the younger trees, possibly implicating differences in metabolic state or distur­bances in protectective mechanisms in the older trees.
The Influence of Alkoxymethyl Purine and Pyrimidine Acyclonucleosides on Growth Inhibition of Kirkman-Robbins Hepatoma and Possible Mechanism of Their Cytostatic Activity
Authors: Modrzejewska Hanna , Greger Janusz , Dramiñski Marcin , Rutkowski Maciej 
Published: August 2018

Abstract
Newly synthesized allyloxymethyl purine and pyrimidine acyclonucleosides [Fig. 1, comp. 1-6] were tested in Syrian hamster, six days after heterotransplantations of Kirkman-Robbins hepatoma and compared with Th5, Th5P and PMT [Fig. 1, comp. 7 -9 ]. 48 hours after intraperitoneal (i.p.) administration of AMT and Th5 in a dose of 80 mg per kg body weight, these compounds reduced tumor weight by 42%, while AMU (in the same dose) by 30%. The inhibition of tumor weight is accompanied by a decrease in dThd and dGuo kinase activities in tumor cytosol by AMU (36% and 33%, respectively) by AM T (59% and 53%, respectively) and by Th5 (58% and 55%, respectively). AMU, AMT and Th5 are phosphorylated in vivo by kinases present in cytosol of growing hepatom a to mono, di and triphosphates, but allyloxymethyl residue of AMU and AMT is first hydrated to hydroxypropoxymethyl residue, having CH2OH group. The lack of phosphorylation of PMT in vivo (having saturated propoxymethyl residue) and phosphorylation of Th5P (when used as a substrate for dNMP kinase) only to Th5 diphosphate suggested that AMU, AM T and Th5 triphosphates are responsible for the inhibition of dTMP and dGMP synthesis.
Fatty Acid Composition of Some Ranunculaceae Seed Oils
Authors: Ucciani Eugène , Debal Alain , Gruber Michel , Wolff Robert L. 
Published: August 2018

Abstract
The fatty acid composition of seed oils of eight Ranunculaceae was determinated in order to characterize new sources of gamma-linolenic acid. Fatty acids were identified as fatty acid methyl esters (FAME) by capillary gas-liquid chromatography (GC) and capillary GC-Fourier transform infrared spectroscopy (FTIR). For trienic FAME the use of a cyanopropyl-polysiloxane stationary phase (CP-Sil 88) allowed the separation with high resolution of methyl ester of columbinic acid (trans-5,cis-9,cis-12 18:3) and gamma-linolenic acid (cis-6,cis-9,cis-12 18:3). The results confirmed the presence of columbinic acid in Thalictrum seed oils, and that of gamma-linolenic acid in Anemone and related species seed oils. The taxonomic subdivision of Ranunculaceae into sub-families and tribes, which resulted from morphological considerations, did not account for the above results.
The Autofluorescent Substance in the Posterior Flagellum of Swarmers of the Brown Alga Scytosiphon lomentaria
Authors: Yamano Kimiaki , Saito Hiroshi , Ogasawara Yukie , Fujii Shoko , Yamada Hiroko , Shirahama Haruhisa , Kawai Hiroshi 
Published: August 2018

Abstract
The flagellar autofluorescent substance of the brown alga Scytosiphon lomentaria , which is probably involved in the photoreception of the phototaxis of flagellate cells, was investi­ gated. 4′,5′-Cyclic FMN (1) was isolated from the extract of whole mature plants for the first time as a natural product. Since the concentration of 4′,5′-cyclic FMN (1) was considerably low in vegetative plants, which do not contain fluorescent flagella, this substance is consid­ered to correspond to the flagellar fluorescent substance.
Anthraquinones in the Leaf Beetle Trirhabda geminata (Chrysomelidae)
Authors: Kunze Arno , Witte Ludger , Aregullin Manuel , Rodriguez Eloy , Proksch Peter 
Published: August 2018

Abstract
Hydroxylated anthraquinones have been found to accumulate in different developmental stages of the chrysomelid beetle Trirhabda geminata. Eggs, larvae and adults were analyzed by HPLC and GC-MS. Each developmental stage analyzed contained 1,8-dihydroxy-3-methyl-anthraquinone (chrysophanol) and 1,8-dihydroxyanthraquinone (chrysazin). No anthraquinones were detected in the faeces of T. geminata. The level of stored anthraqui­ nones did not change during starvation. In the host plant of this specialist herbivore, the brittlebush Encelia farinosa (Asteraceae), anthraquinones were not detected. Possible biolog­ical functions of anthraquinones stored in T. geminata are discussed.
Hydrocarbon Distribution in Epicuticular Waxes of Five Euphorbia Species
Authors: Ahmad Waqar , Nazir Muhammad , Chaudhary Faqir Mohammad , Ahmad Ashfaq 
Published: August 2018

Abstract
The distribution pattern of hydrocarbons in the surface waxes of five species of Euphor­ biaceae, E.caducifolia, E.helioscopia, E.milii, E.royleana and E.tirucalli was studied. In addi­tion to homologous series of n-alkanes, minor quantities of unsaturated and branched hy­drocarbons were also detected. Some of the branched chain hydrocarbons could be explained as having originated from isoprene units and the substituents corresponding to diterpenes and triterpenes.
Reaction of Hypochlorous Acid with Hydrogen Peroxide and tert-Butyl Hydroperoxide. 1H NMR Spectroscopy and Chemiluminescence Analyses
Authors: Arnhold Jürgen , Panasenko Oleg M. , Schiller Jürgen , Arnold Klaus , Vladimirov Yurij A. , Sergienko Valerij I. 
Published: August 2018

Abstract
In contrast to the well-known reaction of hypochlorous acid with hydrogen peroxide, no singlet oxygen is formed as the result of reaction between hypochlorous acid and tert -butyl hydroperoxide. The reaction with hydrogen peroxide yielded a quadratic dependence of light intensity on reactant concentration, a drastic enhancement of luminescence yield using D2O as solvent and only an emission of red light, that are typical characteristics of emission result­ing from two molecules of delta singlet oxygen. Other chemiluminescence properties were observed using tert-butyl hydroperoxide. There was a linear dependence of light intensity on reactant concentration using rm-butyl hydroperoxide in excess with a decline of emission at higher concentrations.

1H-NMR spectroscopic analysis revealed di-tert-butyl peroxide, tert -butanol and also tert-butyl hypochlorite, acetone and acetate as products of the reaction between hypochlorous acid and tert -butyl hydroperoxide. The formation of di-tert-butyl peroxide is only possible assuming a tert-butyloxy radical as primary intermediate product of this reaction.
Our results demonstrate that alkoxy radicals derived from organic hydroperoxides can participate in lipid peroxidation induced by hypochlorous acid. On the other hand, singlet oxygen did not influence the yield of peroxidation products. Changing H2O for D2O in suspension of egg yolk phosphaditylcholine no differences in accumulation of thiobarbituric acid reactive products were observed.
Desialylation of Low Density Lipoprotein -Metabolic Function versus Oxidative Damage ?
Authors: Schlüssel E. H. , Elstner E. F. 
Published: August 2018

Abstract
Low density lipoproteins are generally considered to play a major role in the development of atherosclerotic vascular diseases. There is growing interest in LDL subspecies, especially in their density, carbohydrate content and oxidizability, which is supposed to enhance athero-genicity. We investigated the influence of desialylation on the resistance of the lipoprotein particles towards Cu(II) prooxidative activity.
On the Formation of Weddellite in Chamaecereus silvestrii, a Cactaceae Species from Northern Argentina
Authors: Monje P.V. , Baran E.J. 
Published: August 2018

Abstract
The isolation of well formed crystals of the biomineral weddellite (calcium oxalate dihydrate) from Chamaecereus silvestrii, a Cactaceae species found in the northern part of Argentina, is described. Infrared spectroscopic measurements allow an unambiguous characterization of the nature of the crystals. This is the first report of the presence of a biomineral in this plant species.
Enzyme-Modified Phytotoxic Structure of Thiadiazolidine Compounds
Authors: Senoo Satoshi , Iida Tetsuji , Shouda Kou , Sato Yukiharu , Nicolaus Beate , Böger Peter , Wakabayashi Ko 
Published: August 2018

Abstract
A simple model thiadiazolidine, 5-(4-methoxycarbonylmethylthio-phenylimino)-3,4-tetra-methylene-1,3,4-thiadiazolidin-2-one, was synthesized and its structural modification investigated using glutathione S-transferase (GST) and an esterase preparation isolated from Echinochloa utilis. The objective is a better understanding of the metabolic activation of peroxidizing thiadiazolidine compounds. The model thiadiazolidine with an ester group (thiadiazolidine ester) was isomerized by GST to a more phytotoxic triazolidine structure (triazolidine ester). Both the thiadiazolidine and the more active triazolidine ester were hydrolyzed by Echinochloa esterase to less active free acid compounds. 5-(4-carboxymethylthiophenylimino)-3,4-tetramethylene-1,3,4-thiadiazolidin-2-one (thiadiazolidine acid) and 4-(4-carboxy-methylthiophenyl)-1,2-tetramethylene-1,2,4-triazolidin-3-one-5-thione (triazolidine acid), respectively. The thiadiazolidine acid, however, was only slightly converted into the triazolidine acid in the presence of GST. It is concluded that the thiadiazolidine ester was isomerized in Echinochloa to give the triazolidine acid through the triazolidine ester. Since the triazolidine ester exhibited the highest phytotoxic peroxidizing activity GST is considered as an activating enzyme for phytotoxicity and esterase as a detoxifying enzyme to reduce phytotoxic activity. Accordingly, phytotoxic thiadiazolidine-ester type herbicides may be produced by an interplay of isomerizing GST and esterase activity contributing to herbicide selectivity among plant species.
Uptake and Exudation of Phenolic Compounds by Wheat and Antimicrobial Components of the Root Exudate
Authors: Kobayashi Akio , Kim Myong Jo , Kawazu Kazuyoshi 
Published: August 2018

Abstract
In the course of our study, it was found that phenyl propenoic acid derivatives were readily taken up by wheat. Leaf leachate components were chosen for the feeding experiments and p-coumaric acid, ferulic acid and caffeic acid were found to be quickly taken up into the plants via the roots. The analytical study revealed that the exudate contained potent antimicrobial compounds together with amino acids and sugars.
Besides the primary metabolites, 4-hydroxystyrene, 3-methoxy-4-hydroxystyrene and 3-methoxy-4-acetoxystyrene were identified as exudate components from wheat roots in sterile hydroponic culture. This indicates that these antimicrobial components may play a significant role in the defense system as allelochemicals for the rhizosphere.
Effects of Potassium-(picrate)-(18-crown-6) on the Photosynthetic Electron Transport
Authors: Kovács L. , Hegde U. , Padhye S. , Bernát G. , Demeter S. 
Published: August 2018

Abstract
The effects of potassium-(picrate)-(18-crown-6) on the electron transport of photosystem II was investigated in isolated pea thylakoids. Low concentrations of the compound inhibited the fast decay of fluorescence yield associated with electron transfer between the primary (QA) and secondary (QB) quinone electron acceptor and increased the intermediary level of fluorescence to the Fmax level. The decay half-time of fluorescence yield measured in the presence of DCMU(S2QA
- charge recombination) decreased from about 1.8 s to about 0.3 s in thylakoids treated with potassium-(picrate)-(18-crown-6). While the inhibition of electron transport by DCMU gave rise to the appearance of a thermoluminescence band at about + 10°C (S2QA
- charge recombination) addition of potassium-(picrate)-(18-crown-6) resulted in a thermoluminescence band at about -10°C. Increasing concentrations of potassium-(picrate)-(18-crown-6) diminished the fluorescence yield and the -10°C TL band and abolished the Signal IIS and Signal IIf EPR signals of the tyrosine-D and tyrosine-Z electron donors, respectively. The phenolic-type inhibitor, potassium picrate had the same effect on thermoluminescence and on the tyrosine EPR signals. It is concluded that potassium-(picrate)-(18-crown-6) is a phenolic type inhibitor owing to its picrate constituent. At low concentrations picrate and potassium-(picrate)-18-crown) not only block the electron transport between QA and QB but they probably decrease the midpoint redox potential of QA, as well. At high concentrations they also inhibit the light-induced oxidation of the tyrosine-D and tyrosine-Z donors.
Inhibitors of Chlorophyll Biosynthesis from Bulbs of Gladiolus spp.
Authors: Wübert Joachim , Oster Ulrike , Rüdiger Wolfhart 
Published: August 2018

Abstract
Compounds extracted with methanol from the bulbs of Gladiolus spp. were tested for inhibition of Chl accumulation in greening cress (Lepidium sativum L.) seedlings. For the biotest, cress seeds were imbibed with water for 8 h and then incubated in the dark with the test solution for 40 h. Chlorophyll accumulation was determined at the end of the subsequent irradiation period of 8 h. Compounds active in this biotest were purified by several chromato­ graphic steps and identified by thin-layer chromatography with staining reactions and by gas chromatography/mass spectrometry. The following compounds were identified and their concentration for 50% inhibition of Chl accumulation determined: sucrose (75 mм) plus glucose (30 mм) , 3-hydroxybenzoic acid methylester (0.49 mм) and 5-hydroxymethylfurfural (6.7 mм) . The inhibitory action was compared with several substituted derivatives of the natural compounds.