bluuebunny/crossref_metadata_2025 huggingface dataset:
Antagonistic Effects of α-Tocopherol and α-Tocoquinone in the Regulation of Cyclic Electron Transport around Photosystem II
Authors: Kruk J. , Burda K. , Radunz A. , Strzałka K. , Schmid G. H.
Published: August 2018

α-Tocoquinone (α-TQ ) and α-tocopherol (α-TOC) which cannot substitute for plastoquinone-9 (PQ-A) as an electron acceptor from photosystem II (PS II), influence the oxygen evolution activity of thylakoid membranes under continuous illumination. In the presence of the herbicide DCMU and the protonophore FCCP which stimulate cyclic electron transport around PS II, α-TQ decreased oxygen evolution whereas α-TOC enhanced it. The effects are attributed to a stimulation or an inhibition of cyclic electron transport around PS II by α-TQ and α-TOC, respectively. Results of flash light experiments on PS II preparations show that both α-TQ and α-TOC increased the d-parameter which describes the transition probability from the S3- to the S0-state of the oxygen-evolving complex, although to a smaller extent when PQ-A is added alone to the preparations. The initial S-state distribution in darkadapted samples was changed only upon PQ-A addition and influenced neither by α-TQ nor by α-TO C supplementation. These effects indicate different kinds of interaction of PQ-A, α-TQ and α-TOC with the PS II components. α-TQ increased and α-TOC decreased the “total miss” parameter both in the presence or absence of PQ-A. A possible site of interaction of α-TQ and α-TO C with the cyclic electron transport around PS II is suggested.
Characterization of Hydrogen Photoevolution in Oscillatoria chalybea Detected by Means of Mass Spectrometry
Authors: Abdel-Basset Refat , Bader Klaus P.
Published: August 2018

The filamentous non-heterocystous cyanobacterium Oscillatoria chalybea is capable to photoevolve molecular hydrogen when the cells are flushed to anaerobiosis with nitrogen or argon and exposed to short light flashes or continuous light. The light-induced hydrogen gas exchange of Oscillatoria chalybea has been investigated by direct determination of dynamic changes in the hydrogen partial pressure at m/e=2 in the H/D collector of a mass spectrometric set-up. By means of this technique also the time curves of the light-induced hydrogen gas exchange could be directly recorded. Depending on the chlorophyll concentration in the measuring cell we observed an increasing hydrogen content of the aqueous Oscillatoria suspension i.e. a dark evolution of molecular hydrogen. Upon the onset of light an initial rise of the H 2-signal was observed which was increasingly mixed or followed by a hydrogen uptake. The capability to photoevolve molecular hydrogen was maximal with young cultures and decreased with increasing age. The hydrogen evolution signals require relatively short dark adaptation to get pronounced; few seconds suffice for 2/3 of the hydrogen evolution amplitude. Prolonged dark adaptation maximizes the flash amplitudes. The hydrogen evolu­tion signals do not deactivate by low flash frequency Oscillatoria chalybea evolves molecular hydrogen following growth on nitrogen free or nitrate containing medium. Increase of the oxygen partial pressure of the assays completely abolishes the hydrogen evolution signals with an I50-value of 6 μm.
Andalusol, a Diterpenoid with anti-inflammatory Activity from Siderits foetens Clemen
Authors: Navarro A. , Heras B. de las
Published: August 2018

The anti-inflammatory activity of andalusol (ent-13(16),14-labdadiene-6α,8α,18-triol), a diterpenoid obtained from the acetone extract of Sideritis foetens Clemen, has been investigated. This compound was able to inhibit acute inflammatory processes induced by carrageenan or 12-O -tetradecanoylphorbol acetate (TPA ) after oral or topical administration. Quantitation of the neutrophil specific marker, myeloperoxidase (MPO), demonstrated that its topical anti-inflammatory effect was associated with reduction in neutrophil infiltration into inflamed tissues. Interaction of andalusol with leukocyte functions and histamine release from mast cells was analyzed in vitro. At a concentration of 100 μm andalusol decreased β-glucuronidase release from calcium ionophore A23187-stimulated rat peritoneal leukocytes. However, it failed to affect superoxide generation on TPA -stimulated leukocytes and it was non toxic to leukocytes up to 100 μm (assayed in terms of lactate dehydrogenase release). Andalusol produced a dose-dependent inhibition on histamine release from rat peritoneal mast cells stimulated by com pound 48/80 or calcium ionophore A23187. These results suggest that andalusol possesses an anti-inflammatory profile, and it is in part responsible for the anti-inflammatory activity attributed to this plant.
The Activity of Thymidine Phosphorylase in the Uterine Myomas and the Myometrium in Perimenopausal Women
Authors: Miszczak-Zaborska E. , Greger J. , Kowalska-Koprekh U. , Pajszczyk-Kieszkiewicz T.
Published: August 2018

The activity of thymidine phosphorylase (dThdPase) in the myometrium and uterine myomas has been investigated in perimenopausal women. Differences in the activity of dThdPase have been found depending on the myoma type, menopause stage and the phase of the menstrual cycle in which the surgery was performed. The enzyme in the cytoplasmatic soluble fraction obtain ed at 50 000 x g was the most active in cellular leiomyomas of the follicular phase, the least in adenomyom as of the luteal phase of the menstrual cycle, whereas its activity in myometrium was always unchanged. Greater differences can be observed in the activity of dThdPase after a partial purification of the enzyme from myomas. It seems that the increase in dThdPase activity may point to its correlation with transient, premalignant tumor which may later transform into malignant forms.
Methyl Valerenate, a New Sesquiterpenoid in the Essential Oil from Underground Parts of Valeriana officinalis L. s.l.
Authors: Woerdenbag Herman J. , Bos Rein , Hendriks Henk , Kruizinga Wim H. , Herrema Jan K. , Scheffer Johannes J. C.
Published: August 2018

A new valerenane sesquiterpenoid, methyl valerenate (1), was found in the essential oil from underground parts of Valeriana officinalis L. s.l. Spectral data of methyl valerenate, which was synthesized from valerenic acid (2), are given in this paper.
Cyclic Electron Flow Around Photosystem II as Examined by Photosynthetic Oxygen Evolution Induced by Short Light Flashes
Authors: Gruszecki W. I. , Strzałka K. , Radunz A. , Schmid G. H.
Published: August 2018

Photosynthetic oxygen evolution from photosystem II particles was analyzed as consequence of a train of short (5 μs) flashes of different light quality and different intensities to study cyclic electron flow around photosystem II. Damped oscillations of the amplitudes of O2-evolution corresponding to a flash sequence were fitted numerically and analyzed in terms of a nonhomogeneous distribution of misses, represented by the probability parameter αi. Application of red light, known to promote cyclic electron flow around photosystem II (Gruszecki et al., 1995) results in a considerable increase of all αi, indicating that at the molecular level the misses may be interpreted as resulting from a competition for the reduction of oxidized P680 between cyclic electron flow and the electron flow coming from the water splitting enzyme. In accordance with previous findings, application of light flashes of the spectrum covering the absorption region of carotenoids resulted in an inhibition of cyclic electron flow and a pronounced decrease of the level of the miss parameter. Possible molecular mechanisms for the activity control of this cyclic electron transport around photosystem II by carotenoids are discussed.
Structure -Cytotoxicity Relationships of a Series of Natural and Semi-Synthetic Simple Coumarins as Assessed in Two Human Tumour Cell Lines
Authors: Kolodziej Herbert , Kayser Oliver , Woerdenbag Herman J. , Uden Wim van , Pras Niesko
Published: August 2018

The cytotoxicity of 22 natural and semi-synthetic simple coumarins was evaluated in GLC4, a human small cell lung carcinoma cell line, and in COLO 320, a human colorectal cancer cell line, using the microculture tetrazolium (MTT) assay. With IC50 values > 100 μᴍ , following a continuous (96h) incubation, most coumarins exhibited only low cytotoxicity. Several compounds, however, displayed significant potencies. As far as the structure -cytotoxicity relationship is concerned, it is conspicuous that all the potentially active natural compounds possess at least two phenolic groups in either the 6,7-or 6,8-positions. In addition, the 5-formyl-6-hydroxy substituted semi-synthetic analogue was found to be potent, reflecting the importance of at least two polar functions for high cytotoxicity.
Mechanism of Free and Conjugated Neocarzinostatin Activity: Studies on Chromophore and Protein Uptake Using a Transferrin-Neocarzinostatin Conjugate
Authors: Schönlau Frank , Maibücher Axel , Köhnlein Wolfgang , Garnett Martin C.
Published: August 2018

Targeting studies using the anti-cancer agent neocarzinostatin (NCS), conjugated to anti­ bodies have shown relatively poor specificity. From the literature, it is unclear whether NCS mediates its effects either in conjugated or unconjugated form. In the present work we have used a conjugate of NCS with transferrin, a biological ligand with a well defined endocytic route, to probe these mechanisms. NCS was covalently coupled to transferrin using the heter­ obifunctional reagent sulfo-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC) and 2-iminothiolane to give a stable thioether-linked conjugate with a ratio of 1.6 mol of NCS per mole of transferrin. The binding activity of transferrin was completely retained. Conjugation of NCS to transferrin resulted in an apparent enhancement of cytotoxicity. However, incubation with excess transferrin had no influence on the observed enhanced toxicity, indicating that endocytosis is not responsible.

Further experiments demonstrated that the apparent enhancement was dependent on incubation conditions and not an effect due to endocytosis of ligand. Studies where apo-NCS competed with holo-NCS and transferrin strongly indicated that the cytotoxicity of both NCS and conjugate is mediated by direct entry of the dissociated chromophore into the cell.
Definition of Essential Amino Acid Residues in the Recognition of a Peptide by a Mouse Monoclonal Antibody
Authors: Rosanó Laura , Di Modugno Francesca , Romagnoli Giulia , Chersi Alberto
Published: August 2018

A mouse monoclonal antibody reacting in ELISA with a synthetic peptide representing a linear amino acid stretch of the protein antigen was tested on all overlap­ ping 5-mer to 9-mer fragments of the peptide, as prepared by multi-pin synthesis. Analysis of the binding data suggests that several residues in the peptide might be relatively unrelevant for recognition, while few others seem to play a critical role as key residues. On the basis of such observations, we attempted to reconstruct an alternative essential epitope by introducing multiple amino acid substitutions in the 9-mer peptide exhibiting the best binding activity, and then tested its ability to be recognized by the monoclonal antibody.
Chemical Constituents of Madhuca pasquiery
Authors: Kamperdick Christine , Adam Günter , Hong Van Nguyen , Sung Tran Van
Published: August 2018

Four triterpenoids, the scarce nortriterpenoid platanic acid, two flavonoids and 2,4-dihy-droxyphenylacetic acid methyl ester, hitherto unknown as a natural product, were isolated from Madhuca pasquiery. The structures were established by means of mass and NMR spectroscopy.
Phenolic Compounds from Ageing Shoots of Picea abies
Authors: Kraus Christine A. , Spiteller Gerhard
Published: August 2018

The influence of ageing on the amount and composition of phenolic compounds and their glucosides was studied in one to five-year-old shoots of Picea abies.

The total content of phenolics increased remarkably within the first two years of growth. In this period cinnamic acid derivatives were dominating, but beginning with the end of the first vegetation period a dramatic increase of acetophenones was observed. Obviously at the end of the first vegetation period the cinnamic acid derivatives are subjected to oxidation resulting in an increase of acetophenones.
Biogenesis of the Pyoverdin Chromophore
Authors: Böckmann M. , Taraz K. , Budzikiewicz H.
Published: August 2018

After growing Pseudomonas aeruginosa in the presence of 2 ,4-[4-15N]-diaminobutyric acid (Dab) its incorporation into the quinoline chromophore of the pyoverdin produced by this bacterium could be shown by mass and NMR-spectroscopic techniques. In combination with earlier results it can thus be stated that the precursor of the chromophore is a condensation product of ʟ-Dab and ᴅ-Phe or ᴅ-Tyr. A synthesis for [4 -15N ]-Dab is described.
The Oxidation of Catecholamines and 6-Hydroxydopamine by Molecular Oxygen: Effect of Ascorbate
Authors: Roginsky Vitaly A. , Barsukova Tatjana K. , Bruchelt Gernot , Stegmann Hartmut B.
Published: August 2018

Comparative kinetic studies on the oxidation of catecholamines (CA) (dopamine (DA), epinephrine (EP). norepinephrine (NEP)) serving as a neuromediator in the sympathetic nervous system, 3,4-dihydroxyphenylalanine (DOPA) and 6-hydroxydopamine (6-OHDA), a wellknown neurotoxic agent, were performed in the presence of ascorbate (AscH- ) in 50 mᴍ phosphate buffer, pH 7.40, at 37 °C by using a Clark electrode, EPR and the absorption spectroscopy. The oxidation of CA and DOPA alone was found to be a self-accelerating process, with quinone products (Q) acting as autocatalysts. The rate of oxygen consumption (Rox) increased with time and reached a steady-state level. A starting value of Rox increased in the order: EP < DOPA ≈ NEP ≪ DA ≪ 6-OHDA, whereas a steady-state value of Rox changed in the order: DOPA < DA < NEP ≪ EP ≪ 6-OHDA. The changes in Rox with time were found to correlate with the resistance of primary Q to the intramolecular cyclization.

The effect of AscH- on CA oxidation depended dramatically on whether AscH- was added to non-oxidized or preoxidized CA. Added to non-oxidized CA and DOPA, AscH- inhibited their oxidation (but not that of 6-OHDA). For the case of DA, a pronounced lag period was observed by both a Clark electrode and spectrophotometrically. The addition of AscH- to preoxidized CA, DOPA and 6-OHDA induced an increase in Rox a steadystate concentration of the ascorbyl radical. The kinetic behaviour of the systems was determined by two major factors: 1) AscH- suppressed the formation of Q, a catalyst for CA oxidation, most likely due to the reaction of AscH- with the semiquinone formed from CA; 2) Q derived both from CA and 6-OHDA catalyzed AscH- oxidation. The elevated cytotoxicity of 6-OHDA was found to be in part caused by the condition that 6-OHDA oxidation was not inhibited by AscH- and by the high efficiency of 6-OHDA as a redox cycling agent in combination with A scH−. These observations explain the very pronounced and prolonged cytotoxicity of 6-OHDA even at low concentrations that increases at elevated concentrations of AscH- .
Is Atmospheric Superoxide Vitally Necessary? Accelerated Death of Animals in a Quasi-Neutral Electric Atmosphere
Authors: Goldstein Naum , Arshavskaya Tatyana V.
Published: August 2018

To estimate the necessity of air ions (AIs) as a natural source of atmospheric gaseous superoxide for mammalia the effect of air ion deprivation on mice and rats was investigated. Ambient air deionization inside an experimental acrylic glass cage (AGC) was performed by electrostatic field, built up by acrylic glass surfaces. Under these conditions, four hours after the animals were placed into the AGC, the concentration of negative AIs was not detectable, the concentration of positive ions was (mean ± SD) 77 ± 18 ionsxcm-3. The negative and positive AI concentrations in identical silicate glass cages (control) were 482 ± 128 ionsxcm-3 and 660 ± 148 ionsxcm-3 respectively. It was found that the prolonged deficiency of AIs in ambient air leads to accelerated death of the animals. The life span of the deprived mice and rats was 16.2 ± 0.9 and 23.0 ± 1.1 days respectively. The pathological symptoms and ultrastructural changes in the adeno-and neurohypophysis in deprived animals observed strongly suggest that animal death is related to disturbances in neurohormonal regulation and pituitary insufficiency. The possible physiological need of AIs and atmospheric superox­ide, and its role in the development of environmental stress in human beings and in particular in premature infants is discussed.
New Botrydial Sesquiterpenoids from Hymenoscyphus epiphyllus
Authors: Thines Eckhard , Anke Heidrun , Steglich Wolfgang , Sterner Olov
Published: August 2018

Four new botrydial derivatives, hymendial (1), 7α-hydroxydihydrobotrydial (2), 7α-hy­droxy-10-O-methyldihydrobotrydial (4), and 7α-acetoxy-15α-methoxy-10-O-methyl-dihydro-botrydial (5) were isolated together with dihydrobotrydial (3) from the culture fluid of the ascomycete Hymenoscyphus epiphyllus. In addition, cytochalasin H (6a), 18-deoxycytocha-lasin H (6b) and (+)-mellein (7) were produced by this fungus. Hymendial (1), possessing an a, ß-unsaturated dialdehyde functionality, exhibits antimicrobial and cytotoxic activities and is mutagenic in the Ames Salmonella assay.
A Contribution of the Mitochondrial Adenosinetriphosphatase Inhibitor Protein to the Thermal Stability of the F0F1-ATPase Complex
Authors: Saad-Nehme Jorge , Bezerra Andre L. , Fornells Luz Alba M. , Silva Jerson L. , Meyer-Fernandes Jose R.
Published: August 2018

A complete inactivation is observed after a 3 min pre-incubation at 70 °C with mitochondrial F0F1-ATPase complex depleted of the ATPase natural inhibitor protein (ammonium-Sephadex submitochondrial particles) and activated MgATP-submitochondrial par­ticles (particles that after a 4 h-pre-incubation at 42 °C released the endogenous inhibitor protein). However, latent MgATP-submitochondrial particles (particles containing the inhibi­tor protein) pre-incubated under the same conditions are totally inactivated only after 15 min of pre-incubation. When ammonium-Sephadex particles are reconstituted with 20 μg/ml of purified ATPase inhibitor protein there is an increase of 15-fold in the half-time for ther­mal inactivation (t0.5), showing that the inhibitor protein protects the mitochondrial F0F1-ATPase complex against thermal inactivation.
Transformation of Cholanic Acid Derivatives into Pharmacologically Active Esters of Phenolic Acids by Heterogeneous Wittig Reaction
Authors: Ivanova Antoaneta , Milkova Tsenka , Galabov Angel S. , Nikolaeva Lubomira , Voynova Emilia
Published: August 2018

Steroid esters of cynnamic acid derivatives have been synthesized by a heterogeneous Wittig reaction under sonochemical conditions from the corresponding triphenylphosphonium bro­mides and unprotected phenolic aldehyds using K2CO3 as a base. 5β-Cholan-3α, 7α, 12α, 24-E-ferulate (11') exhibited a marked inhibitory effect on influenza virus A. The synthetic 3α, 24-E-diferulates of 5β-cholan-3α, 24-diol, 5β-cholan-3α, 12α, 24-triol and 5β-cholan-3α, 7α, 12α, 24-tetrol (8, 9 and 12) showed antitumor activity on leukemia P-388 in mice.
Characterization of Proteases from Rhizopus Species after Growth on Soybean Protein
Authors: Heskamp M.-L. , Barz W.
Published: August 2018

Culture filtrates of different fungi of the genus Rhizopus forming tempe (i.e. traditional Indonesian food) were grown on a soybean protein-raffinose-phytate medium and investigated for protease activity using soyprotein as substrate. All isolates belonging to the species R. oryzae, R. stolonifer, R. oligosporus, and R. microsporus var. chinensis, formed the wellknown Rhizopus-pepsin (aspartic proteinase, 35 kD, isoelectric points: 5.9, 5.0, <4) and an additional protease mainly active under alkaline conditions. The new protease (33 kD, isoelectric points: variable and isolate specific) was purified approximately 300-fold and shown to be a serine protease (inhibitor studies). During fungal culture (12 -135 h) the aspartic proteinase is expressed first followed by the serine protease. Both proteases are insensitive to the soybean Kunitz and Bowman-Birk inhibitors. The best rate of soyprotein degradation is achieved by the coordinate action of both proteases at pH 6.5. The examined Rhizopus isolates differ in the time course and intensity of the expression of the alkaline protease
Rapid and Simple Biological Activity Screening of Some Rumex Species; Evaluation of Bioguided Fractions of R. scutatus and Pure Compounds
Authors: Demirezer Ömür L. , Kuruüzüm Ayşe
Published: August 2018

Methanolic extracts of 11 Rumex L. species (Polygonaceae) were examined against brine shrimp and R. scutatus L. has shown significant brine shrimp lethality (LC50=0.96 μg/ml). Methanolic extracts of the roots of R. scutatus were fractionated and the active fraction led to the isolation of 4 anthraquinone aglycones: emodin, chrysophanol, physcion and aloe emodin. Their toxic sequence was found as chrysophanol> aloe emodin> emodin> physcion. These anthraquinone aglycones showed a significant activity with LC50=0.00, LC50=0.01, LC50=0.05, LC50=0.15 μg/ml, respectively
Isolation and Characterization of Cytotoxic Diterpenoid Isomers from Propolis
Authors: Matsuno Tetsuya , Matsumoto Yasuyuki , Saito Masahiro , Morikawa Junji
Published: August 2018

The methanol extract of Brazilian propolis was fractionated by HPLC, based on HuH13 (human hepatocellular carcinoma) cell cytotoxicity assay. Two isomers of diterpenoid with a molecular formula of C20H30O3 (MW: 318.46) were isolated. The structures of these colorless compounds were determined as clerodane diterpenoids (I, 15-oxo-3, 13Z-kolavadien-17-oic acid; II, 15-oxo-3Z, 13E-kolavadien-n-oic acid)
Effect of Aeration on Organic Acid Production by Propionibacterium shermanii
Authors: Quesada-Chanto A. , Schmid-Meyer A. C. , Schroeder A. G. , Silveira M. M. , Carvalho-Jonas M. F. , Artolozaga M. J. , Jonas R.
Published: August 2018

Propionibacteria have been reported as being oxygen sensitive bacteria. Nevertheless, in this work, we intend to show that Propionibacterium shermanii CDB 10014 is able to grow even at high volumetric oxygen transfer coefficients (KLa). Similar final cell concentrations were achieved in experiments at different KLa values, with increasing cell yield from 0.08 g/g cells in anaerobic conditions to 0.22 g/g at KLa 61 h-1. The organic acid production pattern changes depending on the KLa. At KLa higher than 36 h-1, propionic acid was not produced and acetic acid was the main product. At KLa higher than 20h-1, lactic acid began to be produced. In further studies, no important differences in the growth yield were observed in the pH range 5.5-7.0, while the cell production was enhanced by tem peratures in the range 30-35 °C
Antioxidative Activity of Leguminous Seed Extracts Evaluated by Chemiluminescence Methods
Authors: Amarowicz Ryszard , Raab Barbara
Published: August 2018

The antioxidant properties of extracts from seeds of white bean, pea, lentil, everlasting pea, faba bean, and broad bean were investigated by enhanced chemiluminescence (ECL) and photochemiluminescence (PCL) methods. All extracts exhibited antioxidative activity. The antioxidative efficacy of the extracts investigated varied markedly and did not dependent upon their content of phenolic compounds. Results of TLC analysis of the extracts indicated that the antioxidant activity originated from several phenolic compounds, partly similar in their polarity
Chemical and Biological Characterization of Corticrocin, a Yellow Pigment Formed by the Ectomycorrhizal Fungus Piloderma croceum
Authors: Schreiner Thomas , Hildebrandt Ulrich , Bothe Hermann , Marner Franz-Josef
Published: August 2018

Corticrocin is synthesized by mycelia of Piloderma croceum in contrast to mycorradicin, which is deposited into the vacuoles of maize root cells upon colonization with arbuscular mycorrhizal fungi. Corticrocin is formed only when P. croceum is grown in darkness. This indicates that the compound is unlikely of a carotenoid origin which also follows from the chemical structure. Corticrocin is deposited at the surface of the fungal hyphae. The all-E- geometry of the polyunsaturated chain is confirmed by comparing the spectral and chrom atographic properties of the natural product with a synthetic reference.
Substrate Specificity of Chlorophyllase from Different Plants
Authors: Schoch Siegrid , Ihl Monica
Published: August 2018

The activity of chlorophyllase (chlorophyll-chlorophyllido-hydrolase, EC 3.1.1.14) ex­tracted from six different species was compared with enzyme extracted from leaves of Tree of Heaven. The chlorophyllase activity from Swiss chard was similar to the Tree of Heaven enzyme, all the others were less active or inactive. We tested the substrate specificity with bacteriochlorophyll a, chlorophylls a and b. pheophytins a and b and also the synthetic pig­ ments Zn pheophytins a and b and Zn pyropheophytin a. The natural pigments were the best substrates, but the Zn derivatives were also hydrolysed, except Zn pyropheophytin a which was accepted only by the enzyme extracted from the leaves of Tree of Heaven.
Nitidon, a New Bioactive Metabolite from the Basidiomycete Junghuhnia nitida (Pers.: Fr.) Ryv.
Authors: Gehrt Alexandra , Erkel Gerhard , Anke Timm , Sterner Olov
Published: August 2018

Nitidon, a highly oxidised pyranone derivative produced by the basidiomycete Junghuhnia nitida, has been isolated and its biological activities evaluated. The structure was determined by spectroscopic methods. Nitidon exhibits antibiotic and cytotoxic activities and induces morphological and physiological differentiation of tumor cells at nanomolar concentrations.
Hemolytic Activity of Aminoethyl-dodecanoates
Authors: Kleszczyńska H. , Łuczyński J. , Witek S. , Przestalski S.
Published: August 2018

The effect of new lysosomotropic compounds on red blood cell hemolysis and erythrocyte membrane fluidity has been investigated. In earlier studies it was shown that the compounds inhibit the growth of yeast and plasma membrane H+-ATPase activity. The study was per­ formed with eight aminoethyl esters of lauric acid variously substituted at nitrogen atom. Esters of dodecanoic acid were chosen for study because at that chain length dimethylaminoethyl esters showed maximum activity. The hemolytic activity of the substances studied exhib­its diversified activity in their interaction with the erythrocyte membrane: they differ in hemolytic activity and affect membrane fluidity differently. Erythrocyte membrane fluidity changes under the effect of those compounds which possess highest hemolytic activity. The hemolytic activity of the aminoesters investigated was found to follow a sequence that de­pended on basicity (i.e. ability of the protonated form formation) of the compound and its polar head group size. The most active are the compounds that possess not more than four carbon atoms substituted at nitrogen and highest pKa value.
Immobilization of Polymethylgalacturonase Producing Aspergillus niger on Luffa Sponge Material
Authors: Slokoska Ludmila S. , Angelova Maria B.
Published: August 2018

The vegetable sponge of Luffa cylindrica was studied as a matrix for the immobilization of Aspergillus niger 26. p roducer of polymethylgalacturonase (PMG). Entrapped spores could grow and multiply within the lattice of the sponge. The influence of loofa sponge inoculum content, initial spore inoculum content, and du ration of the growth cycle on the enzyme activity and mycelium growth was studied. The best yield of PMG was reach ed with 1 piece of loofa sponge (approx. 0.10 g dry weight), 109 spores per g carrier and 48 h duration of one cycle. Data obtained during long-term semicontinuous cultivation showed that production capacity increased significantly and the production period was extended more than 10 times compared with the free cell culture.
Circadian Synthesis of Light-Harvesting-Chlorophyll-Proteins in Euglena gracilis Is under Translational Control
Authors: Kiinne A. , Pistorius E. , Kloppstech K. , Groot E. de
Published: August 2018

Two proteins with apparent molecular masses of 17 and 24 kD that are synthesized in a circadian manner in the phytoflagellate Euglena gracilis, were recognized as proteins belong­ing to the family of light-harvesting-chlorophyll-proteins (LHCPs) of class I (17 kD) and of class II (24 kD). Identification was achieved by N-terminal sequencing of the proteins isolated from two-dimensional polyacrylamide gels and by detection with an anti-LHCP II se­rum. While it was found that the total amount of LHCPs remains almost constant, when Euglena is grown under diurnal conditions (12 h light and 12 h dark), we could show that the amount of newly synthesized 17 and 24 kD proteins varies about 20-fold with a maximum of synthesis in the light phase. In contrast, the analysis of the mRNA levels at different times revealed only minor differences in the stationary concentration of the LHCP specific mRNA, indicating that the control of LHCP synthesis is at the translational level. Principally, the same finding was obtained using inhibitors of transcription. Thus, it is concluded that the expression of LHCPs in Euglena gracilis in contrast to that of higher plants is primarily regulated at the translational level.
Theoretical Studies on the Tautomeric Properties of Diamino-5-formamidopyrimidines
Authors: Cysewski Piotr
Published: August 2018

The results of theoretical geometry prediction of formamidopyrimidine(fapy)-adenine and fapy-guanine tautomers are presented. Among 54 potential tautomeric structures of fapy-adenine the most stable structure corresponds to the diamino-keto isomer. The solvent effect has insignificant influence on the fapy-adenine tautomers succession. The fapy-guanine has 172 potential isomers. There are three most stable tautomers of this guanine derivative, which may exchange the order depending on the polarity of the environment. In vapour the most probable is the 4-enol-6-keto-diamino tautomer, while in water environment the 4,6-diketo-diamino isomer is dominant. A more polar solvent stabilises more polar fapy-guanine tauto­mers. The geometric parameters and point-atomic charges corresponding to most probable tau­tomers are also supplied.
Caffeoyl Quinic and Tartaric Acids and Flavonoids from Lapsana communis L. subsp. communis (Asteraceae)
Authors: Fontanel D. , Galtier C. , Viel C. , Gueiffier A.
Published: August 2018

Six hydroxycinnamic acids : caffeic acid, chlorogenic acid, 3,5-O-dicaffeoylquinic acid 2-O-caffeoyltartaric acid (caftaric acid) and 2,3-O-dicaffeoyltartaric acid (chicoric acid) have been isolated from Lapsana communis L. subsp. communis aerial parts. Among flavonoids, only isoquercitrin, luteolin and luteolin-7-O-β-glucuronide were identified. Except for chlorogenic acid, these com­ pounds represent the first report in Lapsana communis. Chicoric acid is the major phenylpropanoic constituent in this plant.
Protective Effect of Vitamin E in a Rat Model of Focal Cerebral Ischemia
Authors: Stohrer M. , Eichinger Andrea , Schlachter M. , Stangassinger M.
Published: August 2018

Under certain pathological conditions such as cerebral ischemia and reperfusion the occur­rence of free radicals is remarkably increased. However, only very little information is avail­ able on their quantitative relevance for the pathophysiology and final outcome of diseases. The aim of the present study was to evaluate the contribution of oxygen radicals in the pathogenesis of a stroke. For this purpose a rat model for stroke was used. Two of three vitamin E deficient groups were repleted with different dosages of DL-a-tocopherylacetate. N o signs of vitamin E deficiency could be observed. However, the weight gain during reple­tion was increased in the vitamin E repleted groups. Brain infarction was created by occlusion of the right middle cerebral artery (MCAO) for two hours. After 24 hours the measurements of infarct volumes were taken. The infarct volume of the group with the highest repletion dosage was significantly reduced by 81%. This was also expressed in a higher rate of gait disturbances after MCAO of the deficient animals. The control of vitamin E status exhibited a similar repletion-dependent level in plasma and brain. These results strongly support the hypothesis that the generation of oxygen radicals occurring during reperfusion is an impor­tant aspect of the pathophysiological mechanism in brain infarction.
Phytochemical Study and Antiinflammatory Properties of Lobelia laxiflora L
Authors: Philipov Stefan , Istatkova Ralitsa , Ivanovska Nina , Denkova Pavletta , Tosheva Kalina , Navas Hernàn , Villegas Juan
Published: August 2018

Three new piperidine alkaloids were isolated from stems, leaves and flowers of Lobelia laxiflora L. (Campanulaceae). The structures of racem. cis-8,10-diethyl-3,4-dehydrolobelidiol (1), racem. trans-8-ethyl-10-phenyl-3,4-dehydrolobelidiol (2) and racem. cis-8-ethyl-10-phenyl-3, 4-dehydrolobelidiol (3) were established by spectral analyses. The residues obtained from the ethanol extracts from stems (S), leaves (L), and flowers (F) were applied in carrageenan (Car)-and cobra venom (CV)-induced acute inflammation in mice. A suppression of paw edema formation at a dose of 100 mg kg-1 was established. In this study the antiinflammatory potential of Lobelia I. was regarded in connection with the complement system. The sequential activation and assembly into functional units of complement components can proceed via two different pathways, named classical (CP) and alternative (AP). The ability of the residues, nonalkaloid fractions, alkaloid fractions and the three alkaloids at a concentration from 0.125 to 1.0 mg ml-1 to inhibit complement activation and thus to prevent inflammatory process was estimated in vitro in human serum via both pathways. All of them inhibited complement activity with a predominant action on CP.
Inhibition of RNA Synthesis in vitro by Acridines - Relation between Structure and Activity
Authors: Piestrzeniewicz Mariola K. , Wilmańska Dorota , Studzian Kazimierz , Szemraj Janusz , Czyż Małgorzata , Denny William A. , Gniazdowski Marek
Published: August 2018

The effects of acridine derivatives (proflavine and 2,7-dialkyl derivatives, diacridines and triacridines, 9-aminoacridine carboxamides, and 9-anilinoacridine, amsacrine and its congeners) on overall RNA synthesis in vitro, on synthesis of initiating oligonucleotides and the binding of the enzyme to DNA were studied. The primary mechanism of action is related to inhibition of the enzyme binding to DNA. The acridines (intercalating or non-intercalating and bis-intercalating ligands) assayed here differ in the properties of their complexes with DNA. Correlation is generally observed between inhibition of RNA synthesis in vitro and cytotoxicity in cell cultures for di- and triacridines and 9-aminoacridine carboxamide derivatives. No relationship was found between the effect on RNA polymerase system and biological effects for amsacrine and its derivatives in contrast to the other series of acridines studied here. The aniline ring seems to decrease the inhibitory potency of a ligand. The discrepancy between the biological effect and RNA synthesis inhibition may be due to a different mechanism of cytotoxicity action of amsacrine which is a potent topoisomerase II poison.
Ultraviolet-B Induced Damage to Photosystem II in Intact Filaments of Spirulina platensis
Authors: Kolli Bala Krishna , Tiwari Swati , Mohanty Prasanna
Published: August 2018

When Spirulina platensis filaments were exposed to 0.75 mW.m-2.s-1 of ultraviolet-B radiation (the ultraviolet-B radiation under clear sky condition is ~1.0 mW.m-2.s-1), an inhibition in photosystem II activity was observed, the inhibition being 90% after 90 min exposure. Upon exposure to ultraviolet-B, the room temperature emission characteristics of Spirulina cells were altered when excited with light primarily absorbed by chlorophyll a or phycobilisomes. When the cells were exposed for 3 h the emission at 685 nm (F685), when excited at 440 nm (primarily chlorophyll a absorption), was enhanced compared to 715 nm (F 715) band of photosystem I suggesting a decrease in energy transfer from photosystem II to photosys­ tem I. Similarly, when the cells were excited at 580 nm (primarily the phycobilisomes), the ratio of emission intensity at 685 nm (F685) to that of 655 nm (F655) was decreased in the exposed cells. This change in emission characteristics seems to be linked with the uncoupling of the energy transfer from allophycocyanin to chlorophyll a of photosystem II. A small shift in emission peak positions was also indicated when excited either at 440 nm or 580 nm. Analysis of the fast induction of chlorophyll a transients in the presence and absence of 10 μm 3-(3,4-dichlorophenyl)-l,l-dimethylurea (DCMU) indicated that ultraviolet-B expo­ sure initially affects Qᴀ, the primary stable acceptor of photosystem II, and then the plastoquinone (PQ) pool. Our results on the loss in photosystem Il-catalyzed Hill activity with p-benzoquinone or dichlorobenzoquinone as electron acceptors also supports the contention that ultraviolet-B, even at low dose, initially alters the Qᴀ of photosystem II and subsequently PQ pool. The analysis of functional pool size of Spirulina suggests a substantial decrease in the functional pool size after 2 h UV-B exposure. These results indicate that in Spirulina low intensity of ultraviolet-B initially damages the reaction centre of photosystem II.
The Representation of Space and the Hippocampus in Rats, Robots and Humans
Authors: Burgess Neil , Donnett James G. , O ’Keefe John
Published: August 2018

Experimental evidence suggests that the hippocampus represents locations within an allocentric representation of space. The environmental inputs that underlie the rat’s representa­tion of its own location within an environment (in the firing of place cells) are the distances to walls, and different walls are identified by their allocentric direction from the rat. We propose that the locations of goals in an environment is stored downstream of the place cells, in the subiculum. In addition to firing rate coding, place cells may use phase coding relative to the theta rhythm of the EEG. In some circumstances path integration may be used, in addition to environmental information, as an input to the hippocampal system. A detailed computational model of the hippocampus successfully guides the navigation of a mobile robot. The model’s behaviour is compared to electrophysiological and behavioural data in rats, and implications for the role of the hippocampus in primates are explored.
Modular Organization of Motor Behavior
Authors: Bizzi E. , Saltiei P. , Tresch M.
Published: August 2018

The issue of translating the planning of arm movements into muscle forces is discussed in relation to the recent discovery of structures in the spinal cord. These structures contain circuitry that, when activated, produce precisely balanced contractions in groups of muscles. These synergistic contractions generate forces that direct the limb toward an equilibrium point in space. Remarkably, the force outputs, produced by activating different spinal-cord structures, sum vectorially. This vectorial combination of motor outputs might be a mecha­nism for producing a vast repertoire of motor behaviors in a simple manner.
How It Is to Be the Brain of a Monkey
Authors: Krüger J.
Published: August 2018

Hypotheses are presented on neural peculiarities of the monkey brain that distinguish monkeys from other mammals and man:

- The unique’ feature of cortical tissue is that it can be applied serially. It fulfils some requirements of a powerful visual system.

- The richness of visual as compared to other signals has yielded a basis for recognizing the bodily similarity of oneself to conspecifics. A visuo/motor coupling trained on oneself but applied to conspecifics (“aping”) evolved.

- Long series of (generalized visuo/visual) computations feasible in a very large cortex would produce excessive delays that would not correspond to outer world delays. The new human solution to this is an “offline” system in which temporal relationships are described by excitation patterns. This gives rise to a rapid expansion of the cortex.

- In humans, a “meaning” has to be attributed to the mutual (computational) relationships of excitation patterns in the offline system, by a reference to the corresponding relationships that would be valid in the normal (online) system. “Perception” is a corollary of this.

- The offline treatment of time, together with “aping”, leads to new types of helping and other social interactions.

- Monkeys may be compared to humans not using their offline system in the state of “absent- mindedness”.

- Experimental approaches departing from excitation patterns are discussed
Varieties of Emergence in Artificial and Natural Systems
Authors: Stephan Achim
Published: August 2018

In different disciplines such as philosophy of mind, dynamical systems theory, and connec­tionism the term ‘emergence’ has different jobs to perform. Therefore, various concepts of emergence are developed and examined. While weaker versions are compatible with prop­erty reductionism, stronger versions are not. Within philosophy of mind, particularly within the qualia debate there is a need for a strong notion of emergence, while in discussions of emergent properties of connectionist nets or of dynamical systems one can do with weaker notions of emergence.
Cellular Dynamics of Network Memory
Authors: Fuster Joaquin M.
Published: August 2018

One example of “emergence” is the development, as a result of neural ontogeny and living experience, of cortical networks capable of representing and retaining cognitive information. A large body of evidence from neuropsychology, electrophysiology and neuroimaging indi­cates that so-called working memory and long-term memory share the same neural substrate in the cerebral cortex. That substrate consists in a system of widespread, overlapping and hierarchically organized networks of cortical neurons. In this system, any neuron or group of neurons can be part of many networks, and thus many memories. Working memory is the temporary activation of one such network of long-term memory for the purpose of executing an action in the near future. The activation of the network may be brought about by stimuli that by virtue of prior experience are in some manner associated with the cognitive content of the network, including the response of the organism to those stimuli. The mechanisms by which the network stays activated are presumed to include the recurrent re-entry of impulses through associated neuronal assemblies of the network. Consistent with this notion is the following evidence: (1) working memory depends on the functional integrity of cortico-corti-cal connective loops; and (2) during working memory, remarkable similarities -including “attractor behavior” -have been observed between firing patterns in real cortex and in an artificial recurrent network.
Accurate Spike Synchronization in Cortex
Authors: Rotter Stefan , Aertsen Ad
Published: August 2018

In view of the enormous capacity and complexity of mammalian brains it is evident that a detailed account of their anatomy and physiology alone cannot lead to a complete under­ standing of their function. Computer simulation and mathematical analysis of abstract, yet biologically realistic models for neurons and networks yield additional and useful information about the interplay of the underlying anatomical structures, the physiological processes oper­ating on the neuronal substrate, and the resulting brain functions during the performance of behavioral tasks. We discuss some contributions of such experiment-guided theory to the issue of accurate spike synchronization.
Scavenger Properties of Synthetic Naphthenic Methyl Esters
Authors: Štajner Dubravka , Ćirin-Novta Vera , Pavlovića Aleksandra
Published: August 2018

To study the scavenger properties four naphthenic methyl esters were synthesized. The abilities of the compounds to act as radical scavengers were investigated in an experimental epinephrine/adrenochrome model using enzymic and non-enzymic systems. We found that our particular compounds exhibited radical scavenger activity and superoxide-dismutase activity inhibition. Investigated compounds also showed physiological activity. In the auxin test one compound induced elongation of the wheat coleoptile by 35%.
Strong Increase of 9-Hydroxy-10,12-octadecadienoic Acid in Low Density Lipoprotein after a Hemorrhagic Shock
Authors: Kreil P. , Spiteller G. , Johannes G. , Wagner W.
Published: August 2018

9-hydroxy-10,12-octadecadienoic acid (9-HODE) is generated by lipid peroxidation (LPO) processes in comparison to other marker compounds in at least 10 fold amount. A 10-25 fold increase of this new marker compound in relation to age matched healthy individuals was observed in the low density lipoprotein (LDL) fraction of ten patients suffering from a hemorrhagic shock. The 9-HODE values dropped to normal levels after recovery.

Similarily the 9-HODE content in LDL of patients which had to undergo orthopedic surgery - replacement of their arthritic hip joints by endoprosthesis - were investigated. The rather high HODE values dropped also after recovery reflecting obviously the disappearance of inflammatory processes associated with arthritis.
Phosphonolipids in the Mussel Mytilus galloprovincialis
Authors: Kariotoglou Dimitrios M. , Mastronicolis Sofia K.
Published: August 2018

One of the possible roles of phosphonolipids is that they have a contribution to the protection of cellular integrity and survival of aquatic organisms (mollusca, cnidaria) as these lipids are included at high percentages. The total lipids of the edible mussel Mytilus galloprovincialis (Mollusca, Bivalvia, Mytilidae) were found to constitute 1.27% of fresh tissue. Polar lipid components constitute 61.5% of the total lipids. After separation by Solid Phase Extraction, the polar lipid fraction was separated by two dimensional thin-layer chromatography and the total phosphorus of each component, was determined. The main polar lipids found were: Phosphatidylcholine, 41.6 ± 0.8% (of which 11.3 ± 0.5% was glyceryl ether analog); ceramide aminoethylphosphonate 11.2 ± 0.2% plus 2.8 ± 0.1% another minor species; phosphatidylethanolamine, 26.6 ± 0.5% (of which 12.2 ± 0.3% was glyceryl ether analog). The individual ceramide aminoethylphosphonate species were isolated by preparative thin layer chromatography and the structure of the major one was confirmed by a combination of analytical and chromatographic methods. Saturated fatty acyl groups with 16 carbon atoms were the main components (48.4%) of the major ceramide aminoethylphosphonate species. Diglyceride aminoethyl phosphonates were not found in lipids of M. galloprovincialis.