Science.gov

Sample records for active glutamate analogues

  1. Mammalian folylpoly-. gamma. -glutamate synthetase. 3. Specificity for folate analogues

    SciTech Connect

    George, S.; Cichowicz, D.J.; Shane, B.

    1987-01-27

    A variety of folate analogues were synthesized to explore the specificity of the folate binding site of hog liver folypolyglutamate synthetase and the requirements for catalysis. Modifications of the internal and terminal glutamate moieties of folate cause large drops in on rates and/or affinity for the protein. The only exceptions are glutamine, homocysteate, and ornithine analogues, indicating a less stringent specificity around the delta-carbon of glutamate. It is proposed that initial folate binding to the enzyme involves low-affinity interactions at a pterin and a glutamate site and that the first glutamate bound is the internal residue adjacent to the benzoyl group. Processive movement of the polyglutamate chain through the glutamate site and a possible conformational change in the protein when the terminal residue is bound would result in tight binding and would position the ..gamma..-carboxyl of the terminal glutamate in the correct position for catalysis. The 4-amino substitution of folate increases the on rate for monoglutamate derivatives but severely impairs catalysis with diglutamate derivatives. Pteroylornithine derivatives are the first potent and specific inhibitors of folylpolyglutamate synthetase to be identified and may act as analogues of reaction intermediates. Other folate derivatives with tetrahedral chemistry replacing the peptide bond, such as pteroyl-..gamma..-glutamyl-(psi,CH/sub 2/-NH)-glutamate, retain affinity for the protein but are considerably less effective inhibitors than the ornithine derivatives. Enzyme activity was assayed using (/sup 14/C)glutamate.

  2. Chemoenzymatic synthesis of new 2,4-syn-functionalized (S)-glutamate analogues and structure-activity relationship studies at ionotropic glutamate receptors and excitatory amino acid transporters.

    PubMed

    Assaf, Zeinab; Larsen, Anja P; Venskutonytė, Raminta; Han, Liwei; Abrahamsen, Bjarke; Nielsen, Birgitte; Gajhede, Michael; Kastrup, Jette S; Jensen, Anders A; Pickering, Darryl S; Frydenvang, Karla; Gefflaut, Thierry; Bunch, Lennart

    2013-02-28

    In the mammalian central nervous system, (S)-glutamate (Glu) is released from the presynaptic neuron where it activates a plethora of pre- and postsynaptic Glu receptors. The fast acting ionotropic Glu receptors (iGluRs) are ligand gated ion channels and are believed to be involved in a vast number of neurological functions such as memory and learning, synaptic plasticity, and motor function. The synthesis of 14 enantiopure 2,4-syn-Glu analogues 2b-p is accessed by a short and efficient chemoenzymatic approach starting from readily available cyclohexanone 3. Pharmacological characterization at the iGluRs and EAAT1-3 subtypes revealed analogue 2i as a selective GluK1 ligand with low nanomolar affinity. Two X-ray crystal structures of the key analogue 2i in the ligand-binding domain (LBD) of GluA2 and GluK3 were determined. Partial domain closure was seen in the GluA2-LBD complex with 2i comparable to that induced by kainate. In contrast, full domain closure was observed in the GluK3-LBD complex with 2i, similar to that of GluK3-LBD with glutamate bound.

  3. Second-generation sulfonamide inhibitors of D-glutamic acid-adding enzyme: activity optimisation with conformationally rigid analogues of D-glutamic acid.

    PubMed

    Sosič, Izidor; Barreteau, Hélène; Simčič, Mihael; Sink, Roman; Cesar, Jožko; Zega, Anamarija; Grdadolnik, Simona Golič; Contreras-Martel, Carlos; Dessen, Andréa; Amoroso, Ana; Joris, Bernard; Blanot, Didier; Gobec, Stanislav

    2011-07-01

    D-Glutamic acid-adding enzyme (MurD) catalyses the essential addition of d-glutamic acid to the cytoplasmic peptidoglycan precursor UDP-N-acetylmuramoyl-l-alanine, and as such it represents an important antibacterial drug-discovery target enzyme. Based on a series of naphthalene-N-sulfonyl-d-Glu derivatives synthesised recently, we synthesised two series of new, optimised sulfonamide inhibitors of MurD that incorporate rigidified mimetics of d-Glu. The compounds that contained either constrained d-Glu or related rigid d-Glu mimetics showed significantly better inhibitory activities than the parent compounds, thereby confirming the advantage of molecular rigidisation in the design of MurD inhibitors. The binding modes of the best inhibitors were examined with high-resolution NMR spectroscopy and X-ray crystallography. We have solved a new crystal structure of the complex of MurD with an inhibitor bearing a 4-aminocyclohexane-1,3-dicarboxyl moiety. These data provide an additional step towards the development of sulfonamide inhibitors with potential antibacterial activities. PMID:21524830

  4. Structure of Bacillus subtilis γ-glutamyltranspeptidase in complex with acivicin: diversity of the binding mode of a classical and electrophilic active-site-directed glutamate analogue

    SciTech Connect

    Ida, Tomoyo; Suzuki, Hideyuki; Fukuyama, Keiichi; Hiratake, Jun; Wada, Kei

    2014-02-01

    The binding modes of acivicin, a classical and an electrophilic active-site-directed glutamate analogue, to bacterial γ-glutamyltranspeptidases were found to be diverse. γ-Glutamyltranspeptidase (GGT) is an enzyme that plays a central role in glutathione metabolism, and acivicin is a classical inhibitor of GGT. Here, the structure of acivicin bound to Bacillus subtilis GGT determined by X-ray crystallography to 1.8 Å resolution is presented, in which it binds to the active site in a similar manner to that in Helicobacter pylori GGT, but in a different binding mode to that in Escherichia coli GGT. In B. subtilis GGT, acivicin is bound covalently through its C3 atom with sp{sup 2} hybridization to Thr403 O{sup γ}, the catalytic nucleophile of the enzyme. The results show that acivicin-binding sites are common, but the binding manners and orientations of its five-membered dihydroisoxazole ring are diverse in the binding pockets of GGTs.

  5. New 4-Functionalized Glutamate Analogues Are Selective Agonists at Metabotropic Glutamate Receptor Subtype 2 or Selective Agonists at Metabotropic Glutamate Receptor Group III.

    PubMed

    Huynh, Tri H V; Erichsen, Mette N; Tora, Amélie S; Goudet, Cyril; Sagot, Emmanuelle; Assaf, Zeinab; Thomsen, Christian; Brodbeck, Robb; Stensbøl, Tine B; Bjørn-Yoshimoto, Walden E; Nielsen, Birgitte; Pin, Jean-Philippe; Gefflaut, Thierry; Bunch, Lennart

    2016-02-11

    The metabotropic glutamate (Glu) receptors (mGluRs) play key roles in modulating excitatory neurotransmission in the brain. In all, eight subtypes have been identified and divided into three groups, group I (mGlu1,5), group II (mGlu2,3), and group III (mGlu4,6-8). In this article, we present a L-2,4-syn-substituted Glu analogue, 1d, which displays selective agonist activity at mGlu2 over the remaining mGluR subtypes. A modeling study and redesign of the core scaffold led to the stereoselective synthesis of four new conformationally restricted Glu analogues, 2a-d. Most interestingly, 2a retained a selective agonist activity profile at mGlu2 (EC50 in the micromolar range), whereas 2c/2d were both selective agonists at group III, subtypes mGlu4,6,8. In general, 2d was 20-fold more potent than 2c and potently activated mGlu4,6,8 in the low-mid nanomolar range.

  6. Electrogenic uptake of sulphur-containing analogues of glutamate and aspartate by Müller cells from the salamander retina.

    PubMed Central

    Bouvier, M; Miller, B A; Szatkowski, M; Attwell, D

    1991-01-01

    1. The effect of sulphur-containing analogues of glutamate and aspartate on the membrane current of glial cells was studied by whole-cell clamping Müller cells isolated from the salamander retina. 2. L-Cysteic acid (CA), L-cysteinesulphinic acid (CSA), L-homocysteic acid (HCA), L-homocysteinesulphinic acid (HCSA) and S-sulpho-L-cysteine (SC) all evoked an inward membrane current that was large at negative potentials, and was smaller (but did not reverse) at more positive potentials up to +30 mV. 3. Removal of external sodium ions abolished the amino acid-evoked currents. Whole-cell clamping with pipettes containing no potassium led to a rapid suppression of the currents, that did not occur when potassium was included in the pipette. 4. The dependence of the currents on sulphur-containing amino acid concentration obeyed first-order Michaelis-Menten kinetics. The current evoked by co-application of L-glutamate and a sulphur-containing analogue was smaller than the sum of the currents produced by glutamate alone and by the sulphur analogue alone. 5. These data are consistent with the sulphur amino acid-evoked current being caused by uptake on the electrogenic glutamate uptake carrier, which co-transports an excess of Na+ ions into the cell, and counter-transports one K+ ion out of the cell. 6. The apparent Km (Michaelis-Menten constant) values for activation of uptake by CA (6 microM) and by CSA (60 microM) are low enough for uptake on the glutamate uptake carrier to be a plausible mechanism for terminating the postulated neurotransmitter action of these agents. However, the apparent Km values for uptake of HCA (2.95 mM), HCSA (1.65 mM) and SC (greater than 1 mM) are much higher than the EC50 (half-maximal effective concentration) concentrations for these agents' activation of NMDA (N-methyl-D-aspartate) channels. 7. Comparing the concentrations of sulphur amino acids needed to activate NMDA channels with their rate of uptake suggests that their potency for causing

  7. Mechanism for the activation of glutamate receptors

    Cancer.gov

    Scientists at the NIH have used a technique called cryo-electron microscopy to determine a molecular mechanism for the activation and desensitization of ionotropic glutamate receptors, a prominent class of neurotransmitter receptors in the brain and spina

  8. Glutamate Mediated Astrocytic Filtering of Neuronal Activity

    PubMed Central

    Herzog, Nitzan; De Pittà, Maurizio; Jacob, Eshel Ben; Berry, Hugues; Hanein, Yael

    2014-01-01

    Neuron-astrocyte communication is an important regulatory mechanism in various brain functions but its complexity and role are yet to be fully understood. In particular, the temporal pattern of astrocyte response to neuronal firing has not been fully characterized. Here, we used neuron-astrocyte cultures on multi-electrode arrays coupled to Ca2+ imaging and explored the range of neuronal stimulation frequencies while keeping constant the amount of stimulation. Our results reveal that astrocytes specifically respond to the frequency of neuronal stimulation by intracellular Ca2+ transients, with a clear onset of astrocytic activation at neuron firing rates around 3-5 Hz. The cell-to-cell heterogeneity of the astrocyte Ca2+ response was however large and increasing with stimulation frequency. Astrocytic activation by neurons was abolished with antagonists of type I metabotropic glutamate receptor, validating the glutamate-dependence of this neuron-to-astrocyte pathway. Using a realistic biophysical model of glutamate-based intracellular calcium signaling in astrocytes, we suggest that the stepwise response is due to the supralinear dynamics of intracellular IP3 and that the heterogeneity of the responses may be due to the heterogeneity of the astrocyte-to-astrocyte couplings via gap junction channels. Therefore our results present astrocyte intracellular Ca2+ activity as a nonlinear integrator of glutamate-dependent neuronal activity. PMID:25521344

  9. Antimicrobial activity of resveratrol analogues.

    PubMed

    Chalal, Malik; Klinguer, Agnès; Echairi, Abdelwahad; Meunier, Philippe; Vervandier-Fasseur, Dominique; Adrian, Marielle

    2014-01-01

    Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of activity ranging from low to high. Six of them, including the most active ones, were subsequently tested on the development of Botrytis cinerea (fungus responsible for grey mold). The results obtained allowed us to identify the most active stilbenes against both grapevine pathogens, to compare the antimicrobial activity of the evaluated series of stilbenes, and to discuss the relationship between their chemical structure (number and position of methoxy and hydroxy groups) and antimicrobial activity. PMID:24918540

  10. Antimicrobial activity of resveratrol analogues.

    PubMed

    Chalal, Malik; Klinguer, Agnès; Echairi, Abdelwahad; Meunier, Philippe; Vervandier-Fasseur, Dominique; Adrian, Marielle

    2014-06-10

    Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of activity ranging from low to high. Six of them, including the most active ones, were subsequently tested on the development of Botrytis cinerea (fungus responsible for grey mold). The results obtained allowed us to identify the most active stilbenes against both grapevine pathogens, to compare the antimicrobial activity of the evaluated series of stilbenes, and to discuss the relationship between their chemical structure (number and position of methoxy and hydroxy groups) and antimicrobial activity.

  11. Isoxazole analogues bind the system xc- transporter: structure-activity relationship and pharmacophore model.

    PubMed

    Patel, Sarjubhai A; Rajale, Trideep; O'Brien, Erin; Burkhart, David J; Nelson, Jared K; Twamley, Brendan; Blumenfeld, Alex; Szabon-Watola, Monika I; Gerdes, John M; Bridges, Richard J; Natale, Nicholas R

    2010-01-01

    Analogues of amino methylisoxazole propionic acid (AMPA), were prepared from a common intermediate 12, including lipophilic analogues using lateral metalation and electrophilic quenching, and were evaluated at System xc-. Both the 5-naphthylethyl-(16) and 5-naphthylmethoxymethyl-(17) analogues adopt an E-conformation in the solid state, yet while the former has robust binding at System xc-, the latter is virtually devoid of activity. The most potent analogues were amino acid naphthyl-ACPA 7g, and hydrazone carboxylic acid, 11e Y=Y'=3,5-(CF(3))(2), which both inhibited glutamate uptake by the System xc- transporter with comparable potency to the endogenous substrate cystine, whereas in contrast the closed isoxazolo[3,4-d] pyridazinones 13 have significantly lower activity. A preliminary pharmacophore model has been constructed to provide insight into the analogue structure-activity relationships.

  12. Synthesis and antimicrobial activity of squalamine analogue.

    PubMed

    Kim, H S; Choi, B S; Kwon, K C; Lee, S O; Kwak, H J; Lee, C H

    2000-08-01

    Synthesis and antimicrobial activity of squalamine analogue 2 are reported. The synthesis of 2 was accomplished from bisnoralcohol 3. The spermidine moiety was introduced via reductive amination of an appropriately functionalized 3beta-aminosterol with spermidinyl aldehyde 17 utilizing sodium triacetoxyborohydride as the reducing agent. Compound 2 shows weaker antimicrobial activity than squalamine. PMID:11003150

  13. Neuronal Activity and Glutamate Uptake Decrease Mitochondrial Mobility in Astrocytes and Position Mitochondria Near Glutamate Transporters

    PubMed Central

    Jackson, Joshua G.; O'Donnell, John C.; Takano, Hajime; Coulter, Douglas A.

    2014-01-01

    Within neurons, mitochondria are nonuniformly distributed and are retained at sites of high activity and metabolic demand. Glutamate transport and the concomitant activation of the Na+/K+-ATPase represent a substantial energetic demand on astrocytes. We hypothesized that mitochondrial mobility within astrocytic processes might be regulated by neuronal activity and glutamate transport. We imaged organotypic hippocampal slice cultures of rat, in which astrocytes maintain their highly branched morphologies and express glutamate transporters. Using time-lapse confocal microscopy, the mobility of mitochondria within individual astrocytic processes and neuronal dendrites was tracked. Within neurons, a greater percentage of mitochondria were mobile than in astrocytes. Furthermore, they moved faster and farther than in astrocytes. Inhibiting neuronal activity with tetrodotoxin (TTX) increased the percentage of mobile mitochondria in astrocytes. Mitochondrial movement in astrocytes was inhibited by vinblastine and cytochalasin D, demonstrating that this mobility depends on both the microtubule and actin cytoskeletons. Inhibition of glutamate transport tripled the percentage of mobile mitochondria in astrocytes. Conversely, application of the transporter substrate d-aspartate reversed the TTX-induced increase in the percentage of mobile mitochondria. Inhibition of reversed Na+/Ca2+ exchange also increased the percentage of mitochondria that were mobile. Last, we demonstrated that neuronal activity increases the probability that mitochondria appose GLT-1 particles within astrocyte processes, without changing the proximity of GLT-1 particles to VGLUT1. These results imply that neuronal activity and the resulting clearance of glutamate by astrocytes regulate the movement of astrocytic mitochondria and suggest a mechanism by which glutamate transporters might retain mitochondria at sites of glutamate uptake. PMID:24478345

  14. Digitoxin Analogues with Improved Anticytomegalovirus Activity

    PubMed Central

    2014-01-01

    Cardiac glycosides are potent inhibitors of cancer cell growth and possess antiviral activities at nanomolar concentrations. In this study we evaluated the anticytomegalovirus (CMV) activity of digitoxin and several of its analogues. We show that sugar type and sugar length attached to the steroid core structure affects its anticytomegalovirus activity. Structure–activity relationship (SAR) studies identified the l-sugar containing cardiac glycosides as having improved anti-CMV activity and may lead to better understanding of how these compounds inhibit CMV replication. PMID:24900847

  15. Dipeptide Piracetam Analogue Noopept Improves Viability of Hippocampal HT-22 Neurons in the Glutamate Toxicity Model.

    PubMed

    Antipova, T A; Nikolaev, S V; Ostrovskaya, P U; Gudasheva, T A; Seredenin, S B

    2016-05-01

    Effect of noopept (N-phenylacetyl-prolylglycine ethyl ester) on viability of neurons exposed to neurotoxic action of glutamic acid (5 mM) was studied in vitro in immortalized mouse hippocampal HT-22 neurons. Noopept added to the medium before or after glutamic acid improved neuronal survival in a concentration range of 10-11-10-5 M. Comparison of the effective noopept concentrations determined in previous studies on cultured cortical and cerebellar neurons showed that hippocampal neurons are more sensitive to the protective effect of noopept. PMID:27265136

  16. N-Terminally Glutamate-Substituted Analogue of Gramicidin A as Protonophore and Selective Mitochondrial Uncoupler

    PubMed Central

    Sorochkina, Alexandra I.; Plotnikov, Egor Y.; Rokitskaya, Tatyana I.; Kovalchuk, Sergei I.; Kotova, Elena A.; Sychev, Sergei V.; Zorov, Dmitry B.; Antonenko, Yuri N.

    2012-01-01

    Limited uncoupling of oxidative phosphorylation could be beneficial for cells by preventing excessive generation of reactive oxygen species. Typical uncouplers are weak organic acids capable of permeating across membranes with a narrow gap between efficacy and toxicity. Aimed at designing a nontoxic uncoupler, the protonatable amino acid residue Glu was substituted for Val at the N-terminus of the pentadecapeptide gramicidin A (gA). The modified peptide [Glu1]gA exhibited high uncoupling activity in isolated mitochondria, in particular, abolishing membrane potential at the inner mitochondrial membrane with the same or even larger efficacy as gA. With mitochondria in cell culture, the depolarizing activity of [Glu1]gA was observed at concentrations by an order of magnitude lower than those of gA. On the contrary, [Glu1]gA was much less potent in forming proton channels in planar lipid bilayers than gA. Remarkably, at uncoupling concentrations, [Glu1]gA did not alter cell morphology and was nontoxic in MTT test, in contrast to gA showing high toxicity. The difference in the behavior of [Glu1]gA and gA in natural and artificial membranes could be ascribed to increased capability of [Glu1]gA to permeate through membranes and/or redistribute between different membranes. Based on the protective role of mild uncoupling, [Glu1]gA and some other proton-conducting gA analogues may be considered as prototypes of prospective therapeutic agents. PMID:22911866

  17. N-terminally glutamate-substituted analogue of gramicidin A as protonophore and selective mitochondrial uncoupler.

    PubMed

    Sorochkina, Alexandra I; Plotnikov, Egor Y; Rokitskaya, Tatyana I; Kovalchuk, Sergei I; Kotova, Elena A; Sychev, Sergei V; Zorov, Dmitry B; Antonenko, Yuri N

    2012-01-01

    Limited uncoupling of oxidative phosphorylation could be beneficial for cells by preventing excessive generation of reactive oxygen species. Typical uncouplers are weak organic acids capable of permeating across membranes with a narrow gap between efficacy and toxicity. Aimed at designing a nontoxic uncoupler, the protonatable amino acid residue Glu was substituted for Val at the N-terminus of the pentadecapeptide gramicidin A (gA). The modified peptide [Glu1]gA exhibited high uncoupling activity in isolated mitochondria, in particular, abolishing membrane potential at the inner mitochondrial membrane with the same or even larger efficacy as gA. With mitochondria in cell culture, the depolarizing activity of [Glu1]gA was observed at concentrations by an order of magnitude lower than those of gA. On the contrary, [Glu1]gA was much less potent in forming proton channels in planar lipid bilayers than gA. Remarkably, at uncoupling concentrations, [Glu1]gA did not alter cell morphology and was nontoxic in MTT test, in contrast to gA showing high toxicity. The difference in the behavior of [Glu1]gA and gA in natural and artificial membranes could be ascribed to increased capability of [Glu1]gA to permeate through membranes and/or redistribute between different membranes. Based on the protective role of mild uncoupling, [Glu1]gA and some other proton-conducting gA analogues may be considered as prototypes of prospective therapeutic agents.

  18. Jupiter analogues and planets of active stars

    NASA Astrophysics Data System (ADS)

    Kürster, M.; Zechmeister, M.; Endl, M.; Lo Curto, G.; Hartman, H.; Nilsson, H.; Henning, T.; Hatzes, A. P.; Cochran, W. D.

    2013-04-01

    Combined results are now available from a 15 year long search for Jupiter analogues around solar-type stars using the ESO CAT + CES, ESO 3.6 m + CES, and ESO 3.6 m + HARPS instruments. They comprise planet (co-)discoveries (ι Hor and HR 506) and confirmations (three planets in HR 3259) as well as non-confirmations of planets (HR 4523 and ɛ Eri) announced elsewhere. A long-term trend in ɛ Ind found by our survey is probably attributable to a Jovian planet with a period >30 yr, but we cannot fully exclude stellar activity effects as the cause. A 3.8 year periodic variation in HR 8323 can be attributed to stellar activity.

  19. Aminotransferase and glutamate dehydrogenase activities in lactobacilli and streptococci.

    PubMed

    Peralta, Guillermo Hugo; Bergamini, Carina Viviana; Hynes, Erica Rut

    2016-01-01

    Aminotransferases and glutamate dehydrogenase are two main types of enzymes involved in the initial steps of amino acid catabolism, which plays a key role in the cheese flavor development. In the present work, glutamate dehydrogenase and aminotransferase activities were screened in twenty one strains of lactic acid bacteria of dairy interest, either cheese-isolated or commercial starters, including fifteen mesophilic lactobacilli, four thermophilic lactobacilli, and two streptococci. The strains of Streptococcus thermophilus showed the highest glutamate dehydrogenase activity, which was significantly elevated compared with the lactobacilli. Aspartate aminotransferase prevailed in most strains tested, while the levels and specificity of other aminotransferases were highly strain- and species-dependent. The knowledge of enzymatic profiles of these starter and cheese-isolated cultures is helpful in proposing appropriate combinations of strains for improved or increased cheese flavor. PMID:27266631

  20. Aminotransferase and glutamate dehydrogenase activities in lactobacilli and streptococci.

    PubMed

    Peralta, Guillermo Hugo; Bergamini, Carina Viviana; Hynes, Erica Rut

    2016-01-01

    Aminotransferases and glutamate dehydrogenase are two main types of enzymes involved in the initial steps of amino acid catabolism, which plays a key role in the cheese flavor development. In the present work, glutamate dehydrogenase and aminotransferase activities were screened in twenty one strains of lactic acid bacteria of dairy interest, either cheese-isolated or commercial starters, including fifteen mesophilic lactobacilli, four thermophilic lactobacilli, and two streptococci. The strains of Streptococcus thermophilus showed the highest glutamate dehydrogenase activity, which was significantly elevated compared with the lactobacilli. Aspartate aminotransferase prevailed in most strains tested, while the levels and specificity of other aminotransferases were highly strain- and species-dependent. The knowledge of enzymatic profiles of these starter and cheese-isolated cultures is helpful in proposing appropriate combinations of strains for improved or increased cheese flavor.

  1. Postsynaptic activation at the squid giant synapse by photolytic release of L-glutamate from a 'caged' L-glutamate.

    PubMed Central

    Corrie, J E; DeSantis, A; Katayama, Y; Khodakhah, K; Messenger, J B; Ogden, D C; Trentham, D R

    1993-01-01

    1. Pharmacological evidence suggests L-glutamate is a strong candidate as a transmitter at the giant synapse of the squid. Postsynaptic activation at the giant synapse cannot be effected by conventional application of putative neurotransmitters by iontophoresis or perfusion, apparently because the complex structure of the synapse prevents a sufficiently rapid change in concentration at the postsynaptic membrane. Flash photolytic release of L-glutamate from a pharmacologically inert 'caged' L-glutamate pre-equilibrated in the stellate ganglion of Alloteuthis or Loligo was used to determine whether L-glutamate can produce postsynaptic activation when released rapidly in the synaptic clefts. 2. The preparation, reaction mechanism and properties of the caged L-glutamate, N-1-(2-nitrophenyl)ethoxycarbonyl-L-glutamate, are described. The product quantum yield on photolysis was 0.65 (+/- 0.05). On flash photolysis glutamate release followed a single exponential time-course in the pH range 5.5-7.8. The rate constant was proportional to [H+] and was 93 s-1 at pH 5.5 and 16 degrees C in artificial sea water (ionic strength, I = 0.68 M). 3. At pH 7.8 flash photolysis of caged glutamate pre-equilibrated in the synapse caused only a slow depolarization. A second photolytic release of L-glutamate or transsynaptic activation produced no further depolarization, suggesting desensitization and inactivation of postsynaptic mechanisms by the initial pulse of L-glutamate. 4. Synaptic transmission in the giant synapse was normal at pH 5.5. Flash photolysis at pH 5.5 caused rapid production of L-glutamate within the synaptic cleft and a fast postsynaptic depolarization which generated postsynaptic action potentials.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7901400

  2. Among the twenty classical L-amino acids, only glutamate directly activates metabotropic glutamate receptors.

    PubMed

    Frauli, Mélanie; Neuville, Pascal; Vol, Claire; Pin, Jean-Philippe; Prézeau, Laurent

    2006-02-01

    Under pathophysiological conditions, cellular amino acids can be profusely released from cells into the cerebral interstitial space. Because several class-C G protein coupled receptors (GPCRs) display a broad natural ligand spectrum, being sensitive to more than one endogenous ligand, we wondered whether the related metabotropic glutamate (mGlu) receptors could be modulated by various types of L-amino acids, allowing them to sense large increase in extracellular amino acid concentration. Here, the agonist, antagonist and allosteric effects of the twenty classical L-amino acids were evaluated on the eight mGlu receptor subtypes. We show that, in addition to glutamate (Glu), cysteine, aspartate and asparagine also lead to the activation of mGlu3, 4 and 5. Interestingly, our data demonstrate that the effect of these three amino acids did not result from a direct activation of the receptors, but from an indirect action involving Glu-transporters/exchangers. These data first demonstrate that mGlu receptors, unlike other class-C GPCRs, display an extremely high selectivity towards one ligand. Moreover, our results also show that Glu transport systems allow mGlu receptors to sense large increase in the extracellular concentration of some amino acids. Such a system will certainly lead to a large increase in some mGlu receptor activity under pathological conditions, such as seizure, ischemia or other brain injuries. PMID:16310227

  3. Glutamate Stimulates Local Protein Synthesis in the Axons of Rat Cortical Neurons by Activating α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors and Metabotropic Glutamate Receptors.

    PubMed

    Hsu, Wei-Lun; Chung, Hui-Wen; Wu, Chih-Yueh; Wu, Huei-Ing; Lee, Yu-Tao; Chen, En-Chan; Fang, Weilun; Chang, Yen-Chung

    2015-08-21

    Glutamate is the principal excitatory neurotransmitter in the mammalian CNS. By analyzing the metabolic incorporation of azidohomoalanine, a methionine analogue, in newly synthesized proteins, we find that glutamate treatments up-regulate protein translation not only in intact rat cortical neurons in culture but also in the axons emitting from cortical neurons before making synapses with target cells. The process by which glutamate stimulates local translation in axons begins with the binding of glutamate to the ionotropic AMPA receptors and metabotropic glutamate receptor 1 and members of group 2 metabotropic glutamate receptors on the plasma membrane. Subsequently, the activated mammalian target of rapamycin (mTOR) signaling pathway and the rise in Ca(2+), resulting from Ca(2+) influxes through calcium-permeable AMPA receptors, voltage-gated Ca(2+) channels, and transient receptor potential canonical channels, in axons stimulate the local translation machinery. For comparison, the enhancement effects of brain-derived neurotrophic factor (BDNF) on the local protein synthesis in cortical axons were also studied. The results indicate that Ca(2+) influxes via transient receptor potential canonical channels and activated the mTOR pathway in axons also mediate BDNF stimulation to local protein synthesis. However, glutamate- and BDNF-induced enhancements of translation in axons exhibit different kinetics. Moreover, Ca(2+) and mTOR signaling appear to play roles carrying different weights, respectively, in transducing glutamate- and BDNF-induced enhancements of axonal translation. Thus, our results indicate that exposure to transient increases of glutamate and more lasting increases of BDNF would stimulate local protein synthesis in migrating axons en route to their targets in the developing brain.

  4. The structure activity relationship of discodermolide analogues.

    PubMed

    Shaw, Simon J

    2008-03-01

    The marine polyketide discodermolide is a member of a class of natural products that stabilize microtubules. Many analogues have been synthesized suggesting that few changes can be made to the internal carbon backbone. Both ends of the molecule, however, can be modified. The majority of analogues have been generated via modification of the lactone region. This suggests that significant simplifications can be made in this region provided that the lactone moiety is maintained.

  5. Synthesis, antiarrhythmic activity, and toxicological evaluation of mexiletine analogues.

    PubMed

    Roselli, Mariagrazia; Carocci, Alessia; Budriesi, Roberta; Micucci, Matteo; Toma, Maddalena; Di Cesare Mannelli, Lorenzo; Lovece, Angelo; Catalano, Alessia; Cavalluzzi, Maria Maddalena; Bruno, Claudio; De Palma, Annalisa; Contino, Marialessandra; Perrone, Maria Grazia; Colabufo, Nicola Antonio; Chiarini, Alberto; Franchini, Carlo; Ghelardini, Carla; Habtemariam, Solomon; Lentini, Giovanni

    2016-10-01

    Four mexiletine analogues have been tested for their antiarrhythmic, inotropic, and chronotropic effects on isolated guinea pig heart tissues and to assess calcium antagonist activity, in comparison with the parent compound mexiletine. All analogues showed from moderate to high antiarrhythmic activity. In particular, three of them (1b,c,e) were more active and potent than the reference drug, while exhibiting only modest or no negative inotropic and chronotropic effects and vasorelaxant activity, thus showing high selectivity of action. All compounds showed no cytotoxicity and 1b,c,d did not impair motor coordination. All in, these new analogues exhibit an interesting cardiovascular profile and deserve further investigation. PMID:27267000

  6. Synthesis, antiarrhythmic activity, and toxicological evaluation of mexiletine analogues.

    PubMed

    Roselli, Mariagrazia; Carocci, Alessia; Budriesi, Roberta; Micucci, Matteo; Toma, Maddalena; Di Cesare Mannelli, Lorenzo; Lovece, Angelo; Catalano, Alessia; Cavalluzzi, Maria Maddalena; Bruno, Claudio; De Palma, Annalisa; Contino, Marialessandra; Perrone, Maria Grazia; Colabufo, Nicola Antonio; Chiarini, Alberto; Franchini, Carlo; Ghelardini, Carla; Habtemariam, Solomon; Lentini, Giovanni

    2016-10-01

    Four mexiletine analogues have been tested for their antiarrhythmic, inotropic, and chronotropic effects on isolated guinea pig heart tissues and to assess calcium antagonist activity, in comparison with the parent compound mexiletine. All analogues showed from moderate to high antiarrhythmic activity. In particular, three of them (1b,c,e) were more active and potent than the reference drug, while exhibiting only modest or no negative inotropic and chronotropic effects and vasorelaxant activity, thus showing high selectivity of action. All compounds showed no cytotoxicity and 1b,c,d did not impair motor coordination. All in, these new analogues exhibit an interesting cardiovascular profile and deserve further investigation.

  7. Bisphenol A and Its Analogues Activate Human Pregnane X Receptor

    PubMed Central

    Sui, Yipeng; Ai, Ni; Park, Se-Hyung; Rios-Pilier, Jennifer; Perkins, Jordan T.; Welsh, William J.

    2012-01-01

    Background: Bisphenol A (BPA) is a base chemical used extensively in many consumer products. BPA and its analogues are present in environmental and human samples. Many endocrine-disrupting chemicals, including BPA, have been shown to activate the pregnane X receptor (PXR), a nuclear receptor that functions as a master regulator of xenobiotic metabolism. However, the detailed mechanism by which these chemicals activate PXR remains unknown. Objective: We investigated the mechanism by which BPA interacts with and activates PXR and examined selected BPA analogues to determine whether they bind to and activate PXR. Methods: Cell-based reporter assays, in silico ligand–PXR docking studies, and site-directed mutagenesis were combined to study the interaction between BPA and PXR. We also investigated the influence of BPA and its analogues on the regulation of PXR target genes in human LS180 cells. Results: We found that BPA and several of its analogues are potent agonists for human PXR (hPXR) but do not affect mouse PXR activity. We identified key residues within hPXR’s ligand-binding pocket that constitute points of interaction with BPA. We also deduced the structural requirements of BPA analogues that activate hPXR. BPA and its analogues can also induce PXR target gene expression in human LS180 cells. Conclusions: The present study advances our understanding of the mechanism by which BPA interacts with and activates human PXR. Activation of PXR by BPA may explain some of the adverse effects of BPA in humans. PMID:22214767

  8. In Vitro Neuroprotective and Anti-Inflammatory Activities of Natural and Semi-Synthetic Spirosteroid Analogues.

    PubMed

    García-Pupo, Laura; Zaldo-Castro, Armando; Exarchou, Vassiliki; Tacoronte-Morales, Juan Enrique; Pieters, Luc; Vanden Berghe, Wim; Nuñez-Figueredo, Yanier; Delgado-Hernández, René

    2016-01-01

    Two spirosteroid analogues were synthesized and evaluated for their in vitro neuroprotective activities in PC12 cells, against glutamate-induced excitotoxicity and mitochondrial damage in glucose deprivation conditions, as well as their anti-inflammatory potential in LPS/IFNγ-stimulated microglia primary cultures. We also evaluated the in vitro anti-excitotoxic and anti-inflammatory activities of natural and endogenous steroids. Our results show that the plant-derived steroid solasodine decreased PC12 glutamate-induced excitotoxicity, but not the cell death induced by mitochondrial damage and glucose deprivation. Among the two synthetic spirosteroid analogues, only the (25R)-5α-spirostan-3,6-one (S15) protected PC12 against ischemia-related in vitro models and inhibited NO production, as well as the release of IL-1β by stimulated primary microglia. These findings provide further insights into the role of specific modifications of the A and B rings of sapogenins for their neuroprotective potential. PMID:27483221

  9. Electrogenic glutamate uptake in glial cells is activated by intracellular potassium

    NASA Astrophysics Data System (ADS)

    Barbour, Boris; Brew, Helen; Attwell, David

    1988-09-01

    Uptake of glutamate into glial cells in the CNS maintains the extracellular glutamate concentration below neurotoxic levels and helps terminate its action as a neurotransmitter 1. The co-transport of two sodium ions on the glutamate carrier is thought to provide the energy needed to transport glutamate into cells2,3. We have shown recently that glutamate uptake can be detected electrically because the excess of Na+ ions transported with each glutamate anion results in a net current flow into the cell4. We took advantage of the control of the environment, both inside and outside the cell, provided by whole-cell patch-clamping and now report that glutamate uptake is activated by intracellular potassium and inhibited by extracellular potassium. Our results indicate that one K+ ion is transported out of the cell each time a glutamate anion and three Na+ ions are transported in. A carrier with this stoichiometry can accumulate glutamate against a much greater concentration gradient than a carrier co-transporting one glutamate anion and two Na+ ions. Pathological rises in extracellular potassium concentration will inhibit glutamate uptake by depolarizing glial cells and by preventing the loss of K+ from the glutamate carrier. This will facilitate a rise in the extracellular glutamate concentration to neurotoxic levels and contribute to the neuronal death occurring in brain anoxia and ischaemia.

  10. Structure-activity relationship study of spider polyamine toxins as inhibitors of ionotropic glutamate receptors.

    PubMed

    Xiong, Xiao-Feng; Poulsen, Mette H; Hussein, Rama A; Nørager, Niels G; Strømgaard, Kristian

    2014-12-01

    The spider polyamine toxins Joro spider toxin-3 (JSTX-3) and Nephila polyamine toxins-1 and -8 (NPTX-1 and NPTX-8) are isolated from the venom of the orb-weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only difference, and were recently found to be very potent open-channel blockers of ionotropic glutamate (iGlu) receptors. In this study we designed and synthesized a collection of 24 analogues of these toxins using a recently developed solid-phase synthetic methodology. Systematic variation in two regions of the toxins and subsequent evaluation of biological activity at AMPA and NMDA subtypes of iGlu receptors provided succinct information on structure-activity relationships. In particular, one set of analogues were found to display exquisite selectivity and potency for AMPA receptors relative to the natural products. Thus, this systematic SAR study has provided new pharmacological tools for studies of iGlu receptors.

  11. An examination of aspartate decarboxylase and glutamate decarboxylase activity in mosquitoes

    PubMed Central

    Richardson, Graham; Ding, Haizhen; Rocheleau, Tom; Mayhew, George; Reddy, Erin; Han, Qian; Christensen, Bruce M.; Li, Jianyong

    2010-01-01

    A major pathway of beta-alanine synthesis in insects is through the alpha-decarboxylation of aspartate, but the enzyme involved in the decarboxylation of aspartate has not been clearly defined in mosquitoes and characterized in any insect species. In this study, we expressed two putative mosquito glutamate decarboxylase-like enzymes of mosquitoes and critically analyzed their substrate specificity and biochemical properties. Our results provide clear biochemical evidence establishing that one of them is an aspartate decarboxylase and the other is a glutamate decarboxylase. The mosquito aspartate decarboxylase functions exclusively on the production of beta-alanine with no activity with glutamate. Likewise the mosquito glutamate decarboxylase is highly specific to glutamate with essentially no activity with aspartate. Although insect aspartate decarboxylase shares high sequence identity with glutamate decarboxylase, we are able to closely predict aspartate decarboxylase from glutamate decarboxylase based on the difference of their active site residues. PMID:19842059

  12. Metabolic pathways and activity-dependent modulation of glutamate concentration in the human brain.

    PubMed

    Mangia, Silvia; Giove, Federico; Dinuzzo, Mauro

    2012-11-01

    Glutamate is one of the most versatile molecules present in the human brain, involved in protein synthesis, energy production, ammonia detoxification, and transport of reducing equivalents. Aside from these critical metabolic roles, glutamate plays a major part in brain function, being not only the most abundant excitatory neurotransmitter, but also the precursor for γ-aminobutyric acid, the predominant inhibitory neurotransmitter. Regulation of glutamate levels is pivotal for normal brain function, as abnormal extracellular concentration of glutamate can lead to impaired neurotransmission, neurodegeneration and even neuronal death. Understanding how the neuron-astrocyte functional and metabolic interactions modulate glutamate concentration during different activation status and under physiological and pathological conditions is a challenging task, and can only be tentatively estimated from current literature. In this paper, we focus on describing the various metabolic pathways which potentially affect glutamate concentration in the brain, and emphasize which ones are likely to produce the variations in glutamate concentration observed during enhanced neuronal activity in human studies.

  13. Synthesis and cytotoxic activities of semisynthetic zearalenone analogues.

    PubMed

    Tadpetch, Kwanruthai; Kaewmee, Benyapa; Chantakaew, Kittisak; Kantee, Kawalee; Rukachaisirikul, Vatcharin; Phongpaichit, Souwalak

    2016-08-01

    Zearalenone is a β-resorcylic acid macrolide with various biological activities. Herein we report the synthesis and cytotoxic activities of 34 zearalenone analogues against human oral epidermoid carcinoma (KB) and human breast adenocarcinoma (MCF-7) cells as well as noncancerous Vero cells. Some zearalenone analogues showed moderately enhanced cytotoxic activities against the two cancer cell lines. We have discovered the potential lead compounds with diminished or no cytotoxicity to Vero cells. Preliminary structure-activity relationship studies revealed that the double bond at the 1' and 2' positions of zearalenone core was crucial for cytotoxic activities on both cell lines. In addition, for zearalenol analogues, the unprotected hydroxyl group at C-2 and an alkoxy substituent at C-4 played key roles on cytotoxic effects of both cell lines.

  14. Activity-Dependent Plasticity of Astroglial Potassium and Glutamate Clearance

    PubMed Central

    Cheung, Giselle; Sibille, Jérémie; Zapata, Jonathan; Rouach, Nathalie

    2015-01-01

    Recent evidence has shown that astrocytes play essential roles in synaptic transmission and plasticity. Nevertheless, how neuronal activity alters astroglial functional properties and whether such properties also display specific forms of plasticity still remain elusive. Here, we review research findings supporting this aspect of astrocytes, focusing on their roles in the clearance of extracellular potassium and glutamate, two neuroactive substances promptly released during excitatory synaptic transmission. Their subsequent removal, which is primarily carried out by glial potassium channels and glutamate transporters, is essential for proper functioning of the brain. Similar to neurons, different forms of short- and long-term plasticity in astroglial uptake have been reported. In addition, we also present novel findings showing robust potentiation of astrocytic inward currents in response to repetitive stimulations at mild frequencies, as low as 0.75 Hz, in acute hippocampal slices. Interestingly, neurotransmission was hardly affected at this frequency range, suggesting that astrocytes may be more sensitive to low frequency stimulation and may exhibit stronger plasticity than neurons to prevent hyperexcitability. Taken together, these important findings strongly indicate that astrocytes display both short- and long-term plasticity in their clearance of excess neuroactive substances from the extracellular space, thereby regulating neuronal activity and brain homeostasis. PMID:26346563

  15. Post-synaptic calcium influx at the giant synapse of the squid during activation by glutamate.

    PubMed Central

    Eusebi, F; Miledi, R; Parker, I; Stinnakre, J

    1985-01-01

    Changes in free calcium were monitored in the post-synaptic axon of the giant synapse of the squid, using the calcium indicators aequorin and Arsenazo III. The peak size of the calcium-dependent optical signals recorded from aequorin and Arsenazo III both showed a linear relation with the amount of calcium injected ionophoretically into the axon, but the Arsenazo signal had a slower time course than the aequorin. Ionophoretic application of glutamate to the post-synaptic axon depolarized the axon and caused a rise in intracellular free calcium. Aequorin signals were detected in natural sea water, and their size increased when the calcium concentration in the sea water was raised. Arsenazo signals could be detected only in high-calcium (55 mM) sea water. Intracellular calcium signals were detected also during bath application of several glutamate analogues, including kainate, ibotenate, and aspartate. The peak amplitude of the intracellular calcium signal, monitored with both indicators, increased with increasing ionophoretic glutamate dose, and varied linearly with the integral of the glutamate-induced membrane depolarization. No calcium signals were detected when depolarizations, similar to those produced by glutamate, were induced by current injection in the absence of glutamate. We conclude that glutamate increases the calcium permeability of the post-synaptic membrane, independently of the glutamate-induced depolarization. The glutamate-induced depolarization and the rise in intracellular free calcium increased roughly linearly as the membrane potential was made more negative. Extrapolation of these data indicated that the glutamate depolarization would reduce to zero at about -30 mV, while the calcium signals would be suppressed at about +50 mV. PMID:2869144

  16. Synthesis and biological activities of new side chain and backbone cyclic bradykinin analogues.

    PubMed

    Schumann, C; Seyfarth, L; Greiner, G; Paegelow, I; Reissmann, S

    2002-08-01

    A series of conformationally constrained cyclic analogues of the peptide hormone bradykinin (BK, Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) was synthesized to check different turned structures proposed for the bioactive conformation of BK agonists and antagonists. Cycles differing in the size and direction of the lactam bridge were performed at the C- and N-terminal sequences of the molecule. Glutamic acid and lysine were introduced into the native BK sequence at different positions for cyclization through their side chains. Backbone cyclic analogues were synthesized by incorporation of N-carboxy alkylated and N-amino alkylated amino acids into the peptide chain. Although the coupling of Fmoc-glycine to the N-alkylated phenylalanine derivatives was effected with DIC/HOAt in SPPS, the dipeptide building units with more bulky amino acids were pre-built in solution. For backbone cyclization at the C-terminus an alternative building unit with an acylated reduced peptide bond was preformed in solution. Both types of building units were handled in the SPPS in the same manner as amino acids. The agonistic and antagonistic activities of the cyclic BK analogues were determined in rat uterus (RUT) and guinea-pig ileum (GPI) assays. Additionally, the potentiation of the BK-induced effects was examined. Among the series of cyclic BK agonists only compound 3 with backbone cyclization between positions 2 and 5 shows a significant agonistic activity on RUT. To study the influence of intramolecular ring closure we used an antagonistic analogue with weak activity, [D-Phe7]-BK. Side chain as well as backbone cyclization in the N-terminus of [D-Phe7]-BK resulted in analogues with moderate antagonistic activity on RUT. Also, compound 18 in which a lactam bridge between positions 6 and 9 was achieved via an acylated reduced peptide bond has moderate antagonistic activity on RUT. These results support the hypothesis of turn structures in both parts of the molecule as a requirement for BK

  17. Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors

    PubMed Central

    Gautier, Hélène O. B.; Evans, Kimberley A.; Volbracht, Katrin; James, Rachel; Sitnikov, Sergey; Lundgaard, Iben; James, Fiona; Lao-Peregrin, Cristina; Reynolds, Richard; Franklin, Robin J. M.; Káradóttir, Ragnhildur T

    2015-01-01

    Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a ∼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination. PMID:26439639

  18. Chemotactic peptide analogues. Synthesis and chemotactic activity of N-formyl-Met-Leu-Phe analogues containing (S)-phenylalaninol derivatives.

    PubMed

    Zecchini, G P; Paradisi, M P; Torrini, I; Spisani, S

    1995-09-01

    The synthesis and the biological activity towards human neutrophils of some N-formyl-Met-Leu-Phe-OMe analogues containing (S)-phenylalaninol (Pheol) or its derivatives in place of the native phenylalanine are reported. While the analogue containing Pheol (4) was found to be devoid of significant biological activity, its esters 3 and 5, although inactive as chemoattractants, are able to strongly stimulate superoxide production and are active with a lower efficacy in the lysozyme release. PMID:7487425

  19. [Inhibition of glutamine synthetase activity by biologically active derivatives of glutamic acid].

    PubMed

    Firsova, N A; Selivanova, K M; Alekseeva, L V; Evstigneeva, Z G

    1986-05-01

    The inhibition of activity of glutamine synthetase from Chlorella and porcine brain by 4-hydroxy-D-4-fluoro-D,L- and 4-amino-D,L-glutamic acids diastereoisomers was studied. Each compound was shown to exert the same inhibiting effect on glutamine synthetase from both sources. In case of threo-4-hydroxy-D-glutamic acid the inhibition of the Chlorella enzyme was of a competitive and of a completely mixed type. The enzyme inhibition by 4-fluoro-D, L-glutamic acids seemed to be of a completely non-competitive type. The Ki values for all inhibition reactions were determined. A comparison of biochemical parameters and biological activity revealed that the most effective inhibitors of the enzyme exert a most potent antitumour and antiviral action.

  20. Fungicidal activity of truncated analogues of dihydrosphingosine.

    PubMed

    Thevissen, Karin; Hillaert, Ulrik; Meert, Els M K; Chow, Kuen K; Cammue, Bruno P A; Van Calenbergh, Serge; François, Isabelle E J A

    2008-07-01

    The minimal fungicidal concentration (MFC) of dihydrosphingosine (DHS), phytosphingosine (PHS), and five short-chain DHS derivatives was determined for Candida albicans and Candida glabrata. In this respect, a C15- and a C17-homologue of DHS showed a 2- to 10-fold decreased MFC as compared to native DHS (i.e. C18-DHS). DHS derivatives that were active, that is, comprising 12, 15, 17, or 18 carbon atoms, induced accumulation of reactive oxygen species (ROS) in C. albicans. PMID:18524581

  1. Synthesis and antioxidant activities of Coenzyme Q analogues.

    PubMed

    Wang, Jin; Li, Shuo; Yang, Tao; Yang, Jian

    2014-10-30

    A series of 2,3-dimethoxy-5-methyl-1,4-benzoquinones (Coenzyme Q) substituted at the C-6 position with various groups were designed and synthesized based on the Coenzyme Q10 as potent antioxidant. In vitro antioxidant activities of these compounds were evaluated and compared with commercial antioxidant Coenzyme Q10 employing DPPH assay. All these synthesized Coenzyme Q analogues are found to exhibit good antioxidant activities. Of which Compound 8b bearing a N-benzoylpiperazine group at the C-6 position showed more potent inhibition of DPPH radical than Coenzyme Q10. All these results suggested the applicability of the Coenzyme Q analogues as potent antioxidants for combating oxidative stress.

  2. Synthesis and biological activity of polyalthenol and pentacyclindole analogues.

    PubMed

    Marcos, Isidro S; Moro, Rosalina F; Costales, Isabel; Basabe, Pilar; Díez, David; Gil, Ana; Mollinedo, Faustino; Pérez-de la Rosa, Fátima; Pérez-Roth, Eduardo; Padrón, José M

    2014-02-12

    A series of indole sesquiterpenes analogues of polyalthenol and pentacyclindole have been synthesized starting from ent-halimic acid in order to test their biological activity. These analogues include diverse oxidation levels at the sesquiterpenyl moiety and different functionalization on the indole ring. All synthetic derivatives were tested against a representative panel of Gram positive and Gram negative bacterial strains, and the human solid tumour cell lines A549 (non-small cell lung), HBL-100 (breast), HeLa (cervix), SW1573 (non-small cell lung), T-47D (breast) and WiDr (colon). Overall, the compounds presented activity against the cancer cell lines. The resulting lead, displaying a polyalthenol scaffold, showed GI50 values in the range 1.2-5.7 μM against all cell lines tested. PMID:24412720

  3. Stereochemical Assignment of Strigolactone Analogues Confirms Their Selective Biological Activity.

    PubMed

    Artuso, Emma; Ghibaudi, Elena; Lace, Beatrice; Marabello, Domenica; Vinciguerra, Daniele; Lombardi, Chiara; Koltai, Hinanit; Kapulnik, Yoram; Novero, Mara; Occhiato, Ernesto G; Scarpi, Dina; Parisotto, Stefano; Deagostino, Annamaria; Venturello, Paolo; Mayzlish-Gati, Einav; Bier, Ariel; Prandi, Cristina

    2015-11-25

    Strigolactones (SLs) are new plant hormones with various developmental functions. They are also soil signaling chemicals that are required for establishing beneficial mycorrhizal plant/fungus symbiosis. In addition, SLs play an essential role in inducing seed germination in root-parasitic weeds, which are one of the seven most serious biological threats to food security. There are around 20 natural SLs that are produced by plants in very low quantities. Therefore, most of the knowledge on SL signal transduction and associated molecular events is based on the application of synthetic analogues. Stereochemistry plays a crucial role in the structure-activity relationship of SLs, as compounds with an unnatural D-ring configuration may induce biological effects that are unrelated to SLs. We have synthesized a series of strigolactone analogues, whose absolute configuration has been elucidated and related with their biological activity, thus confirming the high specificity of the response. Analogues bearing the R-configured butenolide moiety showed enhanced biological activity, which highlights the importance of this stereochemical motif. PMID:26502774

  4. Lysophosphatidylserine analogues differentially activate three LysoPS receptors.

    PubMed

    Uwamizu, Akiharu; Inoue, Asuka; Suzuki, Kensuke; Okudaira, Michiyo; Shuto, Akira; Shinjo, Yuji; Ishiguro, Jun; Makide, Kumiko; Ikubo, Masaya; Nakamura, Sho; Jung, Sejin; Sayama, Misa; Otani, Yuko; Ohwada, Tomohiko; Aoki, Junken

    2015-03-01

    Lysophosphatidylserine (1-oleoyl-2 R-lysophosphatidylserine, LysoPS) has been shown to have lipid mediator-like actions such as stimulation of mast cell degranulation and suppression of T lymphocyte proliferation, although the mechanisms of LysoPS actions have been elusive. Recently, three G protein-coupled receptors (LPS1/GPR34, LPS2/P2Y10 and LPS3/GPR174) were found to react specifically with LysoPS, raising the possibility that LysoPS serves as a lipid mediator that exerts its role through these receptors. Previously, we chemically synthesized a number of LysoPS analogues and evaluated them as agonists for mast-cell degranulation. Here, we used a transforming growth factor-α (TGFα) shedding assay to see if these LysoPS analogues activated the three LysoPS receptors. Modification of the serine moiety significantly reduced the ability of the analogues to activate the three LysoPS receptors, whereas modification of other parts resulted in loss of activity in receptor-specific manner. We found that introduction of methyl group to serine moiety (1-oleoyl-lysophosphatidylallothreonine) and removal of sn-2 hydroxyl group (1-oleoyl-2-deoxy-LysoPS) resulted in reduction of reactivity with LPS1 and LPS3, respectively. Accordingly, we synthesized a LysoPS analogue with the two modifications (1-oleoyl-2-deoxy-lysophosphatidylallothreonine) and found it to be an LPS2-selective agonist. These pharmacological tools will definitely help to identify the biological roles of these LysoPS receptors. PMID:25320102

  5. Glutamate and GABA-metabolizing enzymes in post-mortem cerebellum in Alzheimer's disease: phosphate-activated glutaminase and glutamic acid decarboxylase.

    PubMed

    Burbaeva, G Sh; Boksha, I S; Tereshkina, E B; Savushkina, O K; Prokhorova, T A; Vorobyeva, E A

    2014-10-01

    Enzymes of glutamate and GABA metabolism in postmortem cerebellum from patients with Alzheimer's disease (AD) have not been comprehensively studied. The present work reports results of original comparative study on levels of phosphate-activated glutaminase (PAG) and glutamic acid decarboxylase isoenzymes (GAD65/67) in autopsied cerebellum samples from AD patients and matched controls (13 cases in each group) as well as summarizes published evidence for altered levels of PAG and GAD65/67 in AD brain. Altered (decreased) levels of these enzymes and changes in links between amounts of these enzymes and other glutamate-metabolizing enzymes (such as glutamate dehydrogenase and glutamine synthetase-like protein) in AD cerebella suggest significantly impaired glutamate and GABA metabolism in this brain region, which was previously regarded as not substantially involved in AD pathogenesis.

  6. [The Biological Activity of the Sevanol and Its Analogues].

    PubMed

    Osmakov, D I; Koshelev, S G; Belozerova, O A; Kublitski, V S; Andreev, Ya A; Grishin, E V; Kozlov, S A

    2015-01-01

    Previously, from the plant Thymus armeniacus a new lignan sevanol was isolated, it's structure was elucidated and was shown that it effectively inhibits the acid-sensing channel ASIC3 and also exhibits a pronounced analgesic and anti-inflammatory effect. In this work biological activity of the sevanol analog obtained by chemical synthesis from simple precursors, the stereoisomer of sevanol and a precursor molecule represents a half of sevanol was measured in electrophysiological experiments on human ASIC3 channels expressed in Xenopus laevis oocytes. Measured inhibitory activity of a synthetic analogue coincided with the activity ofthe natural molecule. Stereoisomer showed inhibitory activity drop by about a third part, and the precursor molecule showed much less significant activity. In result the significance of functional groups and a spatial configuration of sevanol in order to biological activity was shown that is important to take into account for the optimal synthesis design as well as for new drugs development on its base. PMID:26762099

  7. Acute Modulation of Cortical Glutamate and GABA Content by Physical Activity.

    PubMed

    Maddock, Richard J; Casazza, Gretchen A; Fernandez, Dione H; Maddock, Michael I

    2016-02-24

    Converging evidence demonstrates that physical activity evokes a brain state characterized by distinctive changes in brain metabolism and cortical function. Human studies have shown that physical activity leads to a generalized increase in electroencephalography power across regions and frequencies, and a global increase in brain nonoxidative metabolism of carbohydrate substrates. This nonoxidative consumption of carbohydrate has been hypothesized to include increased de novo synthesis of amino acid neurotransmitters, especially glutamate and GABA. Here, we conducted a series of proton magnetic resonance spectroscopy studies in human volunteers before and after vigorous exercise (≥80% of predicted maximal heart rate). Results showed that the resonance signals of both glutamate and GABA increased significantly in the visual cortex following exercise. We further demonstrated a similar increase in glutamate following exercise in an executive region, the anterior cingulate cortex. The increase in glutamate was similar when using echo times of 30 and 144 ms, indicating that exercise-related T2 relaxation effects across this range of relaxation times did not account for the findings. In addition, we found preliminary evidence that more physical activity during the preceding week predicts higher resting glutamate levels. Overall, the results are consistent with an exercise-induced expansion of the cortical pools of glutamate and GABA, and add to a growing understanding of the distinctive brain state associated with physical activity. A more complete understanding of this brain state may reveal important insights into mechanisms underlying the beneficial effects of physical exercise in neuropsychiatric disorders, neurorehabilitation, aging, and cognition.

  8. Activation of muscarinic receptors inhibits glutamate-induced GSK-3β overactivation in PC12 cells

    PubMed Central

    Ma, Ke; Yang, Li-min; Chen, Hong-zhuan; Lu, Yang

    2013-01-01

    Aim: To investigate the actions of the muscarinic agonist carbachol on glutamate-induced neurotoxicity in PC12 cells, and the underlying mechanisms. Methods: PC12 cells were treated with different concentrations of glutamate for 24 or 48 h. The cell viability was measured using MTT assay, and the expression and activation of GSK-3β were detected with Western blot. β-Catenin translocation was detected using immunofluorescence. Luciferase reporter assay and real-time PCR were used to analyze the transcriptional activity of β-catenin. Results: Glutamate (1, 3, and 10 mmol/L) induced PC12 cell death in a dose-dependent manner. Moreover, treatment of the cells with glutamate (1 mmol/L) caused significant overactivation of GSK-3β and prevented β-catenin translocation to the nucleus. Pretreatment with carbachol (0.01 μmol/L) blocked glutamate-induced cell death and GSK-3β overactivation, and markedly enhanced β-catenin transcriptional activity. Conclusion: Activation of muscarinic receptors exerts neuroprotection in PC12 cells by attenuating glutamate-induced GSK-3β overactivation, suggesting potential benefits of muscarinic agonists for Alzheimer's disease. PMID:23685950

  9. Identification of Ebsulfur Analogues with Broad-Spectrum Antifungal Activity.

    PubMed

    Ngo, Huy X; Shrestha, Sanjib K; Garneau-Tsodikova, Sylvie

    2016-07-19

    Invasive fungal infections are on the rise due to an increased population of critically ill patients as a result of HIV infections, chemotherapies, and organ transplantations. Current antifungal drugs are helpful, but are insufficient in addressing the problem of drug-resistant fungal infections. Thus, there is a growing need for novel antimycotics that are safe and effective. The ebselen scaffold has been evaluated in clinical trials and has been shown to be safe in humans. This makes ebselen an attractive scaffold for facile translation from bench to bedside. We recently reported a library of ebselen-inspired ebsulfur analogues with antibacterial properties, but their antifungal activity has not been characterized. In this study, we repurposed ebselen, ebsulfur, and 32 additional ebsulfur analogues as antifungal agents by evaluating their antifungal activity against a panel of 13 clinically relevant fungal strains. The effect of induction of reactive oxygen species (ROS) by three of these compounds was evaluated. Their hemolytic and cytotoxicity activities were also determined using mouse erythrocytes and mammalian cells. The MIC values of these compounds were found to be in the range of 0.02-12.5 μg mL(-1) against the fungal strains tested. Notably, yeast cells treated with our compounds showed an accumulation of ROS, which may further contribute to the growth-inhibitory effect against fungi. This study provides new lead compounds for the development of antimycotic agents. PMID:27334363

  10. Synthesis and antimalarial activity of new isotebuquine analogues.

    PubMed

    Miroshnikova, Olga V; Hudson, Thomas H; Gerena, Lucia; Kyle, Dennis E; Lin, Ai J

    2007-02-22

    Amodiaquine (AQ) and tebuquine are 4-aminoquinoline antimalarials with Mannich base side chain and are highly effective against chloroquine (CQ)-resistant strains of Plasmodium falciparum. Clinical use of AQ has been severely restricted due to hepatoxicity and agranulocytosis side effects associated with its long term use. Lysosomal accumulation and bioactivation to generate reactive quinoneimine metabolite are implicated to be the cause of the observed AQ toxicities. To avoid the quinoneimine formation and thus the toxicity, a series of isotebuquine analogues and their Nomega-oxides with hydroxy group meta to the amino rather than in para position of the aniline moiety were prepared. The new Mannich bases are highly active against both CQ-sensitive (D6) and -resistant (W2 and TM91C235) clones of P. falciparum with IC50 in the range of 0.3-120 ng/mL. New compounds are1000-fold less toxic (IC50 = 0.7-6 microg/mL) to mouse macrophage cell line than to parasite cell lines. Mono-Mannich bases are more active than bis-Mannich bases. Mono-Mannich base 1a (IC50 = 0.3 ng/mL) is 20-fold more active than the corresponding trifluoromethyl analogue 1b. No appreciable difference in either toxicity or efficacy were observed between the new Mannich bases (m-hydroxyaniline derivatives) 1a or 2a and the corresponding p-hydroxyaniline derivatives.

  11. Allosteric activation of membrane-bound glutamate receptors using coordination chemistry within living cells

    NASA Astrophysics Data System (ADS)

    Kiyonaka, Shigeki; Kubota, Ryou; Michibata, Yukiko; Sakakura, Masayoshi; Takahashi, Hideo; Numata, Tomohiro; Inoue, Ryuji; Yuzaki, Michisuke; Hamachi, Itaru

    2016-10-01

    The controlled activation of proteins in living cells is an important goal in protein-design research, but to introduce an artificial activation switch into membrane proteins through rational design is a significant challenge because of the structural and functional complexity of such proteins. Here we report the allosteric activation of two types of membrane-bound neurotransmitter receptors, the ion-channel type and the G-protein-coupled glutamate receptors, using coordination chemistry in living cells. The high programmability of coordination chemistry enabled two His mutations, which act as an artificial allosteric site, to be semirationally incorporated in the vicinity of the ligand-binding pockets. Binding of Pd(2,2‧-bipyridine) at the allosteric site enabled the active conformations of the glutamate receptors to be stabilized. Using this approach, we were able to activate selectively a mutant glutamate receptor in live neurons, which initiated a subsequent signal-transduction pathway.

  12. Allosteric activation of membrane-bound glutamate receptors using coordination chemistry within living cells.

    PubMed

    Kiyonaka, Shigeki; Kubota, Ryou; Michibata, Yukiko; Sakakura, Masayoshi; Takahashi, Hideo; Numata, Tomohiro; Inoue, Ryuji; Yuzaki, Michisuke; Hamachi, Itaru

    2016-10-01

    The controlled activation of proteins in living cells is an important goal in protein-design research, but to introduce an artificial activation switch into membrane proteins through rational design is a significant challenge because of the structural and functional complexity of such proteins. Here we report the allosteric activation of two types of membrane-bound neurotransmitter receptors, the ion-channel type and the G-protein-coupled glutamate receptors, using coordination chemistry in living cells. The high programmability of coordination chemistry enabled two His mutations, which act as an artificial allosteric site, to be semirationally incorporated in the vicinity of the ligand-binding pockets. Binding of Pd(2,2'-bipyridine) at the allosteric site enabled the active conformations of the glutamate receptors to be stabilized. Using this approach, we were able to activate selectively a mutant glutamate receptor in live neurons, which initiated a subsequent signal-transduction pathway. PMID:27657873

  13. Maternal inflammation leads to impaired glutamate homeostasis and up-regulation of glutamate carboxypeptidase II in activated microglia in the fetal/newborn rabbit brain.

    PubMed

    Zhang, Zhi; Bassam, Bassam; Thomas, Ajit G; Williams, Monica; Liu, Jinhuan; Nance, Elizabeth; Rojas, Camilo; Slusher, Barbara S; Kannan, Sujatha

    2016-10-01

    Astrocyte dysfunction and excessive activation of glutamatergic systems have been implicated in a number of neurologic disorders, including periventricular leukomalacia (PVL) and cerebral palsy (CP). However, the role of chorioamnionitis on glutamate homeostasis in the fetal and neonatal brains is not clearly understood. We have previously shown that intrauterine endotoxin administration results in intense microglial 'activation' and increased pro-inflammatory cytokines in the periventricular region (PVR) of the neonatal rabbit brain. In this study, we assessed the effect of maternal inflammation on key components of the glutamate pathway and its relationship to astrocyte and microglial activation in the fetal and neonatal New Zealand white rabbit brain. We found that intrauterine endotoxin exposure at gestational day 28 (G28) induced acute and prolonged glutamate elevation in the PVR of fetal (G29, 1day post-injury) and postnatal day 1 (PND1, 3days post-injury) brains along with prominent morphological changes in the astrocytes (soma hypertrophy and retracted processes) in the white matter tracts. There was a significant increase in glutaminase and N-Methyl-d-Aspartate receptor (NMDAR) NR2 subunit expression along with decreased glial L-glutamate transporter 1 (GLT-1) in the PVR at G29, that would promote acute dysregulation of glutamate homeostasis. This was accompanied with significantly decreased TGF-β1 at PND1 in CP kits indicating ongoing neuroinflammation. We also show for the first time that glutamate carboxypeptidase II (GCPII) was significantly increased in the activated microglia at the periventricular white matter area in both G29 and PND1 CP kits. This was confirmed by in vitro studies demonstrating that LPS activated primary microglia markedly upregulate GCPII enzymatic activity. These results suggest that maternal intrauterine endotoxin exposure results in early onset and long-lasting dysregulation of glutamate homeostasis, which may be mediated by

  14. Neuroprotective Activity of Pongamia pinnata in Monosodium Glutamate-induced Neurotoxicity in Rats

    PubMed Central

    Swamy, A. H. M. VISWANATHA; Patel, N. L.; Gadad, P. C.; Koti, B. C.; Patel, U. M.; Thippeswamy, A. H. M.; Manjula, D. V.

    2013-01-01

    This study was designed to evaluate the neuroprotective activity of ethanol extract of Pongamia pinnata stem bark in monosodium glutamate-induced neurotoxicity in rats. Neurotoxicity was induced by intraperitoneal injection of monosodium glutamate 2 g per kg body weight daily for 7 days. Ethanol extract of Pongamia pinnata stem bark (200 and 400 mg/kg) was administered orally after 1 h of monosodium glutamate treatment. Dextromethorphan (30 mg/kg, p.o.) was used as standard drug for the comparison. The degree of protection was determined by various behavioural, locomotor, muscle grip activity, lipid peroxidation and measurement of antioxidant status of glutathione, catalase and superoxide dismutase. Estimation of calcium, sodium and potassium ions in brain tissue and gamma aminobutyric acid level in serum was carried out. The histopathological study of brain tissue was also carried out. Treatment with Pongamia pinnata significantly improved monosodium glutamate-induced alteration in behavioural and locomotor activity and muscle strength. Significant decrease in lipid peroxidation and increase in glutathione, superoxide dismutase and catalase was observed in Pongamia pinnata treated group. Further, Pongamia pinnata also significantly reduced the monosodium glutamate-induced excitotoxicity by decreasing the level of Ca+2 and Na+ with concomitant increase in the level of K+. Serum gamma aminobutyric acid level was also increased in Pongamia pinnata treated animals. Further, the histopathological evidence supports the neuroprotective activity of Pongamia pinnata. In conclusion, the present study suggests that the ethanol extract of stem bark of Pongamia pinnata possesses significant neuroprotective activity in albino rats. PMID:24591740

  15. Neuroprotective Activity of Pongamia pinnata in Monosodium Glutamate-induced Neurotoxicity in Rats.

    PubMed

    Swamy, A H M Viswanatha; Patel, N L; Gadad, P C; Koti, B C; Patel, U M; Thippeswamy, A H M; Manjula, D V

    2013-11-01

    This study was designed to evaluate the neuroprotective activity of ethanol extract of Pongamia pinnata stem bark in monosodium glutamate-induced neurotoxicity in rats. Neurotoxicity was induced by intraperitoneal injection of monosodium glutamate 2 g per kg body weight daily for 7 days. Ethanol extract of Pongamia pinnata stem bark (200 and 400 mg/kg) was administered orally after 1 h of monosodium glutamate treatment. Dextromethorphan (30 mg/kg, p.o.) was used as standard drug for the comparison. The degree of protection was determined by various behavioural, locomotor, muscle grip activity, lipid peroxidation and measurement of antioxidant status of glutathione, catalase and superoxide dismutase. Estimation of calcium, sodium and potassium ions in brain tissue and gamma aminobutyric acid level in serum was carried out. The histopathological study of brain tissue was also carried out. Treatment with Pongamia pinnata significantly improved monosodium glutamate-induced alteration in behavioural and locomotor activity and muscle strength. Significant decrease in lipid peroxidation and increase in glutathione, superoxide dismutase and catalase was observed in Pongamia pinnata treated group. Further, Pongamia pinnata also significantly reduced the monosodium glutamate-induced excitotoxicity by decreasing the level of Ca(+2) and Na(+) with concomitant increase in the level of K(+). Serum gamma aminobutyric acid level was also increased in Pongamia pinnata treated animals. Further, the histopathological evidence supports the neuroprotective activity of Pongamia pinnata. In conclusion, the present study suggests that the ethanol extract of stem bark of Pongamia pinnata possesses significant neuroprotective activity in albino rats.

  16. Glutamine synthetase activity and glutamate uptake in hippocampus and frontal cortex in portal hypertensive rats

    PubMed Central

    Acosta, Gabriela Beatriz; Fernández, María Alejandra; Roselló, Diego Martín; Tomaro, María Luján; Balestrasse, Karina; Lemberg, Abraham

    2009-01-01

    AIM: To study glutamine synthetase (GS) activity and glutamate uptake in the hippocampus and frontal cortex (FC) from rats with prehepatic portal vein hypertension. METHODS: Male Wistar rats were divided into sham-operated group and a portal hypertension (PH) group with a regulated stricture of the portal vein. Animals were sacrificed by decapitation 14 d after portal vein stricture. GS activity was determined in the hippocampus and FC. Specific uptake of radiolabeled L-glutamate was studied using synaptosome-enriched fractions that were freshly prepared from both brain areas. RESULTS: We observed that the activity of GS increased in the hippocampus of PH rats, as compared to control animals, and decreased in the FC. A significant decrease in glutamate uptake was found in both brain areas, and was more marked in the hippocampus. The decrease in glutamate uptake might have been caused by a deficient transport function, significantly and persistent increase in this excitatory neurotransmitter activity. CONCLUSION: The presence of moderate ammonia blood levels may add to the toxicity of excitotoxic glutamate in the brain, which causes alterations in brain function. Portal vein stricture that causes portal hypertension modifies the normal function in some brain regions. PMID:19533812

  17. A novel nucleic acid analogue shows strong angiogenic activity

    SciTech Connect

    Tsukamoto, Ikuko; Sakakibara, Norikazu; Maruyama, Tokumi; Igarashi, Junsuke; Kosaka, Hiroaki; Kubota, Yasuo; Tokuda, Masaaki; Ashino, Hiromi; Hattori, Kenichi; Tanaka, Shinji; Kawata, Mitsuhiro; Konishi, Ryoji

    2010-09-03

    Research highlights: {yields} A novel nucleic acid analogue (2Cl-C.OXT-A, m.w. 284) showed angiogenic potency. {yields} It stimulated the tube formation, proliferation and migration of HUVEC in vitro. {yields} 2Cl-C.OXT-A induced the activation of ERK1/2 and MEK in HUVEC. {yields} Angiogenic potency in vivo was confirmed in CAM assay and rabbit cornea assay. {yields} A synthesized small angiogenic agent would have great clinical therapeutic value. -- Abstract: A novel nucleic acid analogue (2Cl-C.OXT-A) significantly stimulated tube formation of human umbilical endothelial cells (HUVEC). Its maximum potency at 100 {mu}M was stronger than that of vascular endothelial growth factor (VEGF), a positive control. At this concentration, 2Cl-C.OXT-A moderately stimulated proliferation as well as migration of HUVEC. To gain mechanistic insights how 2Cl-C.OXT-A promotes angiogenic responses in HUVEC, we performed immunoblot analyses using phospho-specific antibodies as probes. 2Cl-C.OXT-A induced robust phosphorylation/activation of MAP kinase ERK1/2 and an upstream MAP kinase kinase MEK. Conversely, a MEK inhibitor PD98059 abolished ERK1/2 activation and tube formation both enhanced by 2Cl-C.OXT-A. In contrast, MAP kinase responses elicited by 2Cl-C.OXT-A were not inhibited by SU5416, a specific inhibitor of VEGF receptor tyrosine kinase. Collectively these results suggest that 2Cl-C.OXT-A-induces angiogenic responses in HUVEC mediated by a MAP kinase cascade comprising MEK and ERK1/2, but independently of VEGF receptor tyrosine kinase. In vivo assay using chicken chorioallantoic membrane (CAM) and rabbit cornea also suggested the angiogenic potency of 2Cl-C.OXT-A.

  18. Physiological Characterization of Pseudomonas aeruginosa during Exotoxin A Synthesis: Glutamate, Iron Limitation, and Aconitase Activity

    PubMed Central

    Somerville, Greg; Mikoryak, Carole Ann; Reitzer, Larry

    1999-01-01

    Glutamate enhances the yield of exotoxin A (ETA), which is induced by iron limitation, from Pseudomonas aeruginosa. We tested the possibility that glutamate affects growth during iron restriction. We confirmed that iron limitation caused early entry into stationary phase but had no effect on the exponential growth rate. We showed that glutamate, as well as citrate and isocitrate, partially overcame this growth limitation. Glutamate had no effect on toxA (ETA-encoding) transcription, which implies that glutamate primarily increases the number of toxin-producing cells. In contrast, citrate and isocitrate diminished toxA transcription. Since glutamate, citrate, and isocitrate stimulated growth, we suspected a block in the citric acid cycle. Iron limitation reduced the activity of the iron-containing aconitase 12-fold but had no effect on isocitrate dehydrogenase activity, which was assayed as a control. There is a reciprocal relationship between aconitase activity and ETA synthesis, and this correlation does not appear to be coincidental because aconitase-specific effectors affect ETA synthesis. We tested whether a metabolic block is sufficient to induce ETA synthesis, but an aconitase-specific inhibitor diminished ETA production, which argues against this possibility. Finally, we present preliminary evidence that iron limitation may reversibly and posttranslationally inactivate aconitase in vivo. In summary, the environmental factors that stimulate ETA synthesis are related: glutamate bypasses an iron limitation-dependent metabolic block that causes entry into stationary phase. We speculate that one or more of the aconitases in P. aeruginosa may contribute to the control of virulence factor synthesis. PMID:9973331

  19. Elevated venous glutamate levels in (pre)catabolic conditions result at least partly from a decreased glutamate transport activity.

    PubMed

    Hack, V; Stütz, O; Kinscherf, R; Schykowski, M; Kellerer, M; Holm, E; Dröge, W

    1996-06-01

    Abnormally high postabsorptive venous plasma glutamate levels have been reported for several diseases that are associated with a loss of body cell mass including cancer, human/simian immunodeficiency virus infection, and amyotrophic lateral sclerosis. Studies on exchange rates in well-nourished cancer patients now show that high venous plasma glutamate levels may serve as a bona fide indicator for a decreased uptake of glutamate by the peripheral muscle tissue in the postabsorptive period and may be indicative for a precachectic state. High glutamate levels are also moderately correlated with a decreased uptake of glucose and ketone bodies. Relatively high venous glutamate levels have also been found in non-insulin-dependent diabetes mellitus and to some extent also in the cubital vein of normal elderly subjects, i.e., in conditions commonly associated with a decreased glucose tolerance and progressive loss of body cell mass.

  20. Structural and biochemical characterization of the folyl-poly-γ-l-glutamate hydrolyzing activity of human glutamate carboxypeptidase II.

    PubMed

    Navrátil, Michal; Ptáček, Jakub; Šácha, Pavel; Starková, Jana; Lubkowski, Jacek; Bařinka, Cyril; Konvalinka, Jan

    2014-07-01

    In addition to its well-characterized role in the central nervous system, human glutamate carboxypeptidase II (GCPII; Uniprot ID Q04609) acts as a folate hydrolase in the small intestine, participating in the absorption of dietary polyglutamylated folates (folyl-n-γ-l-glutamic acid), which are the provitamin form of folic acid (also known as vitamin B9 ). Despite the role of GCPII as a folate hydrolase, nothing is known about the processing of polyglutamylated folates by GCPII at the structural or enzymological level. Moreover, many epidemiologic studies on the relationship of the naturally occurring His475Tyr polymorphism to folic acid status suggest that this polymorphism may be associated with several pathologies linked to impaired folate metabolism. In the present study, we report: (a) a series X-ray structures of complexes between a catalytically inactive GCPII mutant (Glu424Ala) and a panel of naturally occurring polyglutamylated folates; (b) the X-ray structure of the His475Tyr variant at a resolution of 1.83 Å; (c) the study of the recently identified arene-binding site of GCPII through mutagenesis (Arg463Leu, Arg511Leu and Trp541Ala), inhibitor binding and enzyme kinetics with polyglutamylated folates as substrates; and (d) a comparison of the thermal stabilities and folate-hydrolyzing activities of GCPII wild-type and His475Tyr variants. As a result, the crystallographic data reveal considerable details about the binding mode of polyglutamylated folates to GCPII, especially the engagement of the arene binding site in recognizing the folic acid moiety. Additionally, the combined structural and kinetic data suggest that GCPII wild-type and His475Tyr variant are functionally identical. PMID:24863754

  1. Capsaicin and its analogues: structure-activity relationship study.

    PubMed

    Huang, X-F; Xue, J-Y; Jiang, A-Q; Zhu, H-L

    2013-01-01

    Capsaicin, the main ingredient responsible for the hot pungent taste of chilli peppers, is an alkaloid found in the Capsicum family. Capsaicin was traditionally used for muscular pain, headaches, to improve circulation and for its gastrointestinal protective effects. It was also commonly added to herbal formulations because it acts as a catalyst for other herbs and aids in their absorption. In addition, capsaicin and other capsaicinoid compounds showed strong evidence of having promising potential in the fight against many types of cancer. The mechanism of action of capsaicin has been extensively studied over the past decade. It has been established that capsaicin binds to the transient receptor potential vanilloid 1 receptor which was expressed predominantly by sensory neurons. And many analogues of capsaicin have been synthesized and evaluated for diverse bioactivities. In this review, we will attempt to summarize the biology and structure-activity relationship of capsaicinoids.

  2. Biological activity of modified and exchanged 2-amino-5-nitrothiazole amide analogues of nitazoxanide.

    PubMed

    Ballard, T Eric; Wang, Xia; Olekhnovich, Igor; Koerner, Taylor; Seymour, Craig; Hoffman, Paul S; Macdonald, Timothy L

    2010-06-15

    Head group analogues of the antibacterial and antiparasitic drug nitazoxanide (NTZ) are presented. A library of 39 analogues was synthesized and assayed for their ability to suppress growth of Helicobacter pylori, Campylobacter jejuni, Clostridium difficile and inhibit NTZ target pyruvate:ferredoxin oxidoreductase (PFOR). Two head groups assayed recapitulated NTZ activity and possessed improved activity over their 2-amino-5-nitrothiazole counterparts, demonstrating that head group modification is a viable route for the synthesis of NTZ-related antibacterial analogues. PMID:20488706

  3. Traumatic Brain Injury Increases Cortical Glutamate Network Activity by Compromising GABAergic Control

    PubMed Central

    Cantu, David; Walker, Kendall; Andresen, Lauren; Taylor-Weiner, Amaro; Hampton, David; Tesco, Giuseppina; Dulla, Chris G.

    2015-01-01

    Traumatic brain injury (TBI) is a major risk factor for developing pharmaco-resistant epilepsy. Although disruptions in brain circuitry are associated with TBI, the precise mechanisms by which brain injury leads to epileptiform network activity is unknown. Using controlled cortical impact (CCI) as a model of TBI, we examined how cortical excitability and glutamatergic signaling was altered following injury. We optically mapped cortical glutamate signaling using FRET-based glutamate biosensors, while simultaneously recording cortical field potentials in acute brain slices 2–4 weeks following CCI. Cortical electrical stimulation evoked polyphasic, epileptiform field potentials and disrupted the input–output relationship in deep layers of CCI-injured cortex. High-speed glutamate biosensor imaging showed that glutamate signaling was significantly increased in the injured cortex. Elevated glutamate responses correlated with epileptiform activity, were highest directly adjacent to the injury, and spread via deep cortical layers. Immunoreactivity for markers of GABAergic interneurons were significantly decreased throughout CCI cortex. Lastly, spontaneous inhibitory postsynaptic current frequency decreased and spontaneous excitatory postsynaptic current increased after CCI injury. Our results suggest that specific cortical neuronal microcircuits may initiate and facilitate the spread of epileptiform activity following TBI. Increased glutamatergic signaling due to loss of GABAergic control may provide a mechanism by which TBI can give rise to post-traumatic epilepsy. PMID:24610117

  4. Voltage-dependent drug blockade of L-glutamate activated channels of the crayfish.

    PubMed Central

    Dekin, M S; Edwards, C

    1983-01-01

    The actions of d-tubocurarine (d-TC) and local anaesthetics on the L-glutamate activated channel at the voltage-clamped crayfish neuromuscular junction were studied. The effect of d-TC and local anaesthetics on the dose-response relationship between ionophoretically applied L-glutamate and synaptic current suggested that both acted as non-competitive inhibitors. The amount of inhibition was voltage dependent, and increased as the membrane potential was hyperpolarized. This voltage-dependent block was also manifest in a flattening of the I-V relationship between L-glutamate induced current and membrane potential in the presence of d-TC. However, the reversal potential for the L-glutamate activated channel was not affected; it was about +7 mV in both the presence and absence of d-TC. The neurally evoked excitatory post-synaptic current (e.p.s.c.) was depressed in the presence of these drugs and this effect was also voltage dependent. The time course of the e.p.s.c. was affected, but less so than expected if the L-glutamate activated channel were identical to the channel opened by acetylcholine at the vertebrate neuromuscular junction. Possible reasons for this discrepancy are discussed. PMID:6312026

  5. Solubilization, partial purification, and reconstitution of glutamate- and N-methyl-D-aspartate-activated cation channels from brain synaptic membranes

    SciTech Connect

    Ly, A.M.; Michaelis, E.K. )

    1991-04-30

    L-Glutamate-activated cation channel proteins from rat brain synaptic membranes were solubilized, partially purified, and reconstituted into liposomes. Optimal conditions for solubilization and reconstitution included treatment of the membranes with nonionic detergents in the presence of neutral phospholipids plus glycerol. Quench-flow procedures were developed to characterize the rapid kinetics of ion flux induced by receptor agonists. ({sup 14}C)Methylamine, a cation that permeates through the open channel of both vertebrate and invertebrate glutamate receptors, was used to measure the activity of glutamate receptor-ion channel complexes in reconstituted liposomes. L-Glutamate caused an increase in the rate of ({sup 14}C)methylamine influx into liposomes reconstituted with either solubilized membrane proteins or partially purified glutamate-binding proteins. Of the major glutamate receptor agonists, only N-methyl-D-aspartate activated cation fluxes in liposomes reconstituted with glutamate-binding proteins. In liposomes reconstituted with glutamate-binding proteins, N-methyl-D-aspartate- or glutamate-induced influx of NA{sup +} led to a transient increase in the influx of the lipid-permeable anion probe S{sup 14}CN{sup {minus}}. These results indicate the functional reconstitution of N-methyl-D-aspartate-sensitive glutamate receptors and the role of the {approximately}69-kDa protein in the function of these ion channels.

  6. Antimicrobial Activity of Xanthohumol and Its Selected Structural Analogues.

    PubMed

    Stompor, Monika; Żarowska, Barbara

    2016-01-01

    The objective of this study was to evaluate the antimicrobial activity of structural analogues of xanthohumol 1, a flavonoid compound found in hops (Humulus lupulus). The agar-diffusion method using filter paper disks was applied. Biological tests performed for selected strains of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, fungi (Alternaria sp.), and yeasts (Rhodotorula rubra, Candida albicans) revealed that compounds with at least one hydroxyl group-all of them have it at the C-4 position-demonstrated good activity. Our research showed that the strain S. aureus was more sensitive to chalcones than to the isomers in which the heterocyclic ring C is closed (flavanones). The strain R. rubra was moderately sensitive to only one compound: 4-hydroxy-4'-methoxychalcone 8. Loss of the hydroxyl group in the B-ring of 4'-methoxychalcones or its replacement by a halogen atom (-Cl, -Br), nitro group (-NO₂), ethoxy group (-OCH₂CH₃), or aliphatic substituent (-CH₃, -CH₂CH₃) resulted in the loss of antimicrobial activity towards both R. rubra yeast and S. aureus bacteria. Xanthohumol 1, naringenin 5, and chalconaringenin 7 inhibited growth of S. aureus, whereas 4-hydroxy-4'-methoxychalcone 8 was active towards two strains: S. aureus and R. rubra. PMID:27187329

  7. Resveratrol Prevents Retinal Dysfunction by Regulating Glutamate Transporters, Glutamine Synthetase Expression and Activity in Diabetic Retina.

    PubMed

    Zeng, Kaihong; Yang, Na; Wang, Duozi; Li, Suping; Ming, Jian; Wang, Jing; Yu, Xuemei; Song, Yi; Zhou, Xue; Yang, Yongtao

    2016-05-01

    This study investigated the effects of resveratrol (RSV) on retinal functions, glutamate transporters (GLAST) and glutamine synthetase (GS) expression in diabetic rats retina, and on glutamate uptake, GS activity, GLAST and GS expression in high glucose-cultured Müller cells. The electroretinogram was used to evaluate retinal functions. Müller cells cultures were prepared from 5- to 7-day-old Sprague-Dawley rats. The expression of GLAST and GS was examined by qRT-PCR, ELISA and western-blotting. Glutamate uptake was measured as (3)H-glutamate contents of the lysates. GS activity was assessed by a spectrophotometric assay. 1- to 7-month RSV administrations (5 and 10 mg/kg/day) significantly alleviated hyperglycemia and weight loss in diabetic rats. RSV administrations also significantly attenuated diabetes-induced decreases in amplitude of a-wave in rod response, decreases in amplitude of a-, and b-wave in cone and rod response and decreases in amplitude of OP2 in oscillatory potentials. 1- to 7-month RSV treatments also significantly inhibited diabetes-induced delay in OP2 implicit times in scotopic 3.0 OPS test. The down-regulated mRNA and protein expression of GLAST and GS in diabetic rats retina was prevented by RSV administrations. In high glucose-treated cultures, Müller cells' glutamate uptake, GS activity, GLAST and GS expression were decreased significantly compared with normal control cultures. RSV (10, 20, and 30 mmol/l) significantly inhibited the HG-induced decreases in glutamate uptake, GS activity, GLAST and GS expression (at least P < 0.05). These beneficial results suggest that RSV may be considered as a therapeutic option to prevent from diabetic retinopathy.

  8. Α-amino-β-fluorocyclopropanecarboxylic acids as a new tool for drug development: synthesis of glutamic acid analogs and agonist activity towards metabotropic glutamate receptor 4.

    PubMed

    Lemonnier, Gérald; Lion, Cédric; Quirion, Jean-Charles; Pin, Jean-Philippe; Goudet, Cyril; Jubault, Philippe

    2012-08-01

    Herein we describe the diastereoselective synthesis of glutamic acid analogs and the evaluation of their agonist activity towards metabotropic glutamate receptor subtype 4 (mGluR4). These analogs are based on a monofluorinated cyclopropane core substituted with an α-aminoacid function. The potential of this new building block as a tool for the development of a novel class of drugs is demonstrated with racemic analog 11a that displayed the best agonist activity with an EC50 of 340 nM.

  9. Effects of 3-aminoglutarate, a "silent" false transmitter for glutamate neurons, on synaptic transmission and epileptiform activity.

    PubMed

    Wu, Zheng; Foster, Alan C; Staubli, Ursula; Wu, Xia; Sun, Chicheng; Tang, Xin; Li, Yong-Xin; Chen, Gong

    2015-10-01

    Pharmacological tools that interact with the mechanisms that regulate vesicular filling and release of the neurotransmitter L-glutamate would be of enormous value. In this study, we provide physiological evidence that the glutamate analog, 3-aminoglutarate (3-AG), acts as a false transmitter to reduce presynaptic glutamate release. 3-AG inhibits glutamate-mediated neurotransmission both in primary neuronal cultures and in brain slices with more intact neural circuits. When assayed with the low affinity glutamate receptor antagonist γ-DGG, we demonstrate that 3-AG significantly reduces the synaptic cleft glutamate concentration, suggesting that 3-AG may act as a false transmitter to compete with glutamate during vesicle filling. Furthermore, using three different epileptic models (Mg(2+)-free, 4-AP, and high K(+)), we demonstrate that 3-AG is capable of suppressing epileptiform activity both before and after its induction. Our studies, along with those of the companion paper by Foster et al. (2015) indicate that 3-AG is a "silent" false transmitter for glutamate neurons that is a useful pharmacological tool to probe the mechanisms governing vesicular storage and release of glutamate under both physiological and pathophysiological conditions. 3-AG may have potential therapeutic value in conditions where the glutamate neurotransmitter system is pathologically overactive.

  10. Exposure to high glutamate concentration activates aerobic glycolysis but inhibits ATP-linked respiration in cultured cortical astrocytes.

    PubMed

    Shen, Yao; Tian, Yueyang; Shi, Xiaojie; Yang, Jianbo; Ouyang, Li; Gao, Jieqiong; Lu, Jianxin

    2014-08-01

    Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate-induced gliotoxicity. Exposure to 10-mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non-mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP-linked respiration of astrocytes was reduced. The glutamate-induced astrocyte damage can be mimicked by the non-metabolized substrate d-aspartate but reversed by the non-selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate-induced gliotoxicity in cortical astrocytes.

  11. Valine but not leucine or isoleucine supports neurotransmitter glutamate synthesis during synaptic activity in cultured cerebellar neurons.

    PubMed

    Bak, Lasse K; Johansen, Maja L; Schousboe, Arne; Waagepetersen, Helle S

    2012-09-01

    Synthesis of neuronal glutamate from α-ketoglutarate for neurotransmission necessitates an amino group nitrogen donor; however, it is not clear which amino acid(s) serves this role. Thus, the ability of the three branched-chain amino acids (BCAAs), leucine, isoleucine, and valine, to act as amino group nitrogen donors for synthesis of vesicular neurotransmitter glutamate was investigated in cultured mouse cerebellar (primarily glutamatergic) neurons. The cultures were superfused in the presence of (15) N-labeled BCAAs, and synaptic activity was induced by pulses of N-methyl-D-aspartate (300 μM), which results in release of vesicular glutamate. At the end of the superfusion experiment, the vesicular pool of glutamate was released by treatment with α-latrotoxin (3 nM, 5 min). This experimental paradigm allows a separate analysis of the cytoplasmic and vesicular pools of glutamate. Amount and extent of (15) N labeling of intracellular amino acids plus vesicular glutamate were analyzed employing HPLC and LC-MS analysis. Only when [(15) N]valine served as precursor did the labeling of both cytoplasmic and vesicular glutamate increase after synaptic activity. In addition, only [(15) N]valine was able to maintain the amount of vesicular glutamate during synaptic activity. This indicates that, among the BCAAs, only valine supports the increased need for synthesis of vesicular glutamate.

  12. Semisynthetic analogues of the microtubule-stabilizing agent discodermolide: preparation and biological activity.

    PubMed

    Gunasekera, Sarath P; Longley, Ross E; Isbrucker, Richard A

    2002-12-01

    A series of 12 semisynthetic discodermolide analogues, 2-13, have been prepared using natural (+)-discodermolide (1) and evaluated for in vitro cytotoxicity against cultured murine P-388 leukemia and A-549 human adenocarcinoma cells. These semisynthetic analogues showed a significant variation of cytotoxicity and confirmed the importance of the C-7 through C-19 molecular fragment for potency. Specifically, these analogues suggested the importance of the C-11 and C-17 hydroxyl groups and the C-13 double bond for the potency of discodermolide. The preparation, structure elucidation, and biological activity of these new analogues are described.

  13. Conformationally-restricted amino acid analogues bearing a distal sulfonic acid show selective inhibition of system x(c)(-) over the vesicular glutamate transporter.

    PubMed

    Etoga, Jean-Louis G; Ahmed, S Kaleem; Patel, Sarjubhai; Bridges, Richard J; Thompson, Charles M

    2010-04-15

    A panel of amino acid analogs and conformationally-restricted amino acids bearing a sulfonic acid were synthesized and tested for their ability to preferentially inhibit the obligate cysteine-glutamate transporter system x(c)(-) versus the vesicular glutamate transporter (VGLUT). Several promising candidate molecules were identified: R/S-4-[4'-carboxyphenyl]-phenylglycine, a biphenyl substituted analog of 4-carboxyphenylglycine and 2-thiopheneglycine-5-sulfonic acid both of which reduced glutamate uptake at system x(c)(-) by 70-75% while having modest to no effect on glutamate uptake at VGLUT.

  14. Synthesis and structure-activity relationship studies of novel 2-diarylethyl substituted (2-carboxycycloprop-1-yl)glycines as high-affinity group II metabotropic glutamate receptor ligands.

    PubMed

    Sørensen, Ulrik S; Bleisch, Thomas J; Kingston, Anne E; Wright, Rebecca A; Johnson, Bryan G; Schoepp, Darryle D; Ornstein, Paul L

    2003-01-17

    The major excitatory neurotransmitter in the central nervous system, (S)-glutamic acid , activates both ionotropic and metabotropic excitatory amino acid receptors. Its importance in connection to neurological and psychiatric disorders has directed great attention to the development of compounds that modulate the effects of this endogenous ligand. Whereas L-carboxycyclopropylglycine (L-CCG-1) is a potent agonist at, primarily, group II metabotropic glutamate receptors, alkylation of at the alpha-carbon notoriously result in group II mGluR antagonists, of which the most potent compound described so far, LY341495, displays IC(50) values of 23 and 10 nM at the group II receptor subtypes mGlu2 and mGlu3, respectively. In this study we synthesized a series of structural analogues of in which the xanthyl moiety is replaced by two substituted-phenyl groups. The pharmacological characterization shows that these novel compounds have very high affinity for group II mGluRs when tested as their racemates. The most potent analogues demonstrate K(i) values in the range of 5-12 nM, being thus comparable to LY341495. PMID:12470714

  15. Rhodomycin analogues from Streptomyces purpurascens: isolation, characterization and biological activities.

    PubMed

    Holkar, Sunita; Begde, Deovrat; Nashikkar, Nandita; Kadam, Tukaram; Upadhyay, Avinash

    2013-12-01

    During a screening program for bioactive natural products, a potential Streptomyces sp was isolated from soil. On the basis of biochemical, cultural, physiological and 16S rRNA gene analysis, it was identified as Streptomyces purpurascens. The isolate was grown in liquid medium and the crude antibiotic complex was obtained by ethyl acetate extraction. Seven purified fractions were obtained by preparative Thin Layer Chromatography (TLC). Acid hydrolysis of each fraction and subsequent TLC led to the identification of aglycones and sugars indicating these compounds to be Rhodomycin and its analogues. The identity of these compounds was established on the basis of UV-visible and FT-IR spectra and comparison with published data. The compounds were active against Gram-positive bacteria. Compound E, identified as Rhodomycin B, was found to be the most potent compound with an MIC of 2 μg/ml against Bacillus subtilis. Compounds A and F identified as α2-Rhodomycin II and Obelmycin respectively, and Compound E exhibited an IC50 of 8.8 μg/ml against HeLa cell line but no cytotoxicity was found against L929.

  16. Glutamate activation of Oct-2 in cultured chick Bergmann glia cells: involvement of NFkappaB.

    PubMed

    Méndez, J Alfredo; López-Bayghen, Esther; Ortega, Arturo

    2005-07-01

    Glutamate, the major excitatory neurotransmitter in the central nervous system, is critically involved in gene expression regulation at the transcriptional and translational levels. Its activity through ionotropic as well as metabotropic receptors modifies the protein repertoire in neurons and glial cells. In avian cerebellar Bergmann glia cells, glutamate receptors trigger a diverse array of signaling cascades that include activity-dependent transcription factors such as the activator protein-1, the cAMP response-element binding protein, and Oct-2. We analyze the upstream regulatory elements involved in Oct-2 activation. Our results demonstrate that Ca2+ influx, protein kinase C, phosphatidylinositol-3 kinase, Src, and nuclear factor (NF)kappaB are involved in this signaling pathway. Our findings link alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor activation to a negative phase of chkbp gene regulation, controlled by NFkappaB.

  17. Convergence of dopamine and glutamate signaling onto striatal ERK activation in response to drugs of abuse

    PubMed Central

    Cahill, Emma; Salery, Marine; Vanhoutte, Peter; Caboche, Jocelyne

    2014-01-01

    Despite their distinct targets, all addictive drugs commonly abused by humans evoke increases in dopamine (DA) concentration within the striatum. The main DA Guanine nucleotide binding protein couple receptors (GPCRs) expressed by medium-sized spiny neurons of the striatum are the D1R and D2R, which are positively and negatively coupled to cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling, respectively. These two DA GPCRs are largely segregated into distinct neuronal populations, where they are co-expressed with glutamate receptors in dendritic spines. Direct and indirect interactions between DA GPCRs and glutamate receptors are the molecular basis by which DA modulates glutamate transmission and controls striatal plasticity and behavior induced by drugs of abuse. A major downstream target of striatal D1R is the extracellular signal-regulated kinase (ERK) kinase pathway. ERK activation by drugs of abuse behaves as a key integrator of D1R and glutamate NMDAR signaling. Once activated, ERK can trigger chromatin remodeling and induce gene expression that permits long-term cellular alterations and drug-induced morphological and behavioral changes. Besides the classical cAMP/PKA pathway, downstream of D1R, recent evidence implicates a cAMP-independent crosstalk mechanism by which the D1R potentiates NMDAR-mediated calcium influx and ERK activation. The mounting evidence of reciprocal modulation of DA and glutamate receptors adds further intricacy to striatal synaptic signaling and is liable to prove relevant for addictive drug-induced signaling, plasticity, and behavior. Herein, we review the evidence that built our understanding of the consequences of this synergistic signaling for the actions of drugs of abuse. PMID:24409148

  18. Gabapentin inhibits the activity of the rat excitatory glutamate transporter 3 expressed in Xenopus oocytes.

    PubMed

    Gil, Yang Sook; Kim, Jong Hak; Kim, Chi Hyo; Han, Jong In; Zuo, Zhiyi; Baik, Hee Jung

    2015-09-01

    Gabapentin, a derivative of γ-aminobutyric acid (GABA), is used to treat epilepsy and neuropathic pain. The pharmacological mechanisms for gabapentin effects are not completely elucidated. We investigated the effect of gabapentin on the activity of excitatory amino acid transporter 3 (EAAT3) that can regulate extracellular glutamate concentrations. EAAT3 was expressed in Xenopus oocytes. Membrane currents were recorded after application of l-glutamate in the presence or absence of different concentrations of gabapentin (1-300μM) by using a two-electrode voltage clamp. To determine the effect of gabapentin on Vmax and Km of EAAT3 for l-glutamate, l-glutamate at 3-300μM was used. To study the effects of protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K) on gabapentin-induced changes in EAAT3 activity, oocytes were incubated with the PKC activator (Phorbol 12-myristate 13-acetate, PMA), the PKC inhibitors (chelerythrine or staurosporine), and the PI3K inhibitor wortmannin. Gabapentin decreased EAAT3 activity in a concentration-dependent manner and EAAT3 activity was significantly inhibited by 10-300μM gabapentin. Gabapentin significantly decreased Vmax without affecting Km. PMA increased EAAT3 activity; however, gabapentin attenuated the PMA-induced increase in EAAT3 activity. Pre-incubation of oocytes with chelerythrine, staurosporine, or wortmannin decreased basal EAAT3 activity, which was further reduced by gabapentin. We conclude that gabapentin decreases EAAT3 activity at clinically relevant and higher concentrations, in which PKC and PI3K may not be involved. The results suggest that EAAT3 might not be a target for the anticonvulsant action of gabapentin.

  19. Metabotropic glutamate receptors activate dendritic calcium waves and TRPM channels which drive rhythmic respiratory patterns in mice

    PubMed Central

    Mironov, S L

    2008-01-01

    Respiration in vertebrates is generated by a compact network which is located in the lower brainstem but cellular mechanisms which underlie persistent oscillatory activity of the respiratory network are yet unknown. Using two-photon imaging and patch-clamp recordings in functional brainstem preparations of mice containing pre-Bötzinger complex (preBötC), we examined the actions of metabotropic glutamate receptors (mGluR1/5) on the respiratory patterns. The agonist DHPG potentiated and antagonist LY367385 depressed respiration-related activities. In the inspiratory neurons, we observed rhythmic activation of non-selective channels which had a conductance of 24 pS. Their activity was enhanced with membrane depolarization and after elevation of calcium from the cytoplasmic side of the membrane. They were activated by a non-hydrolysable PIP2 analogue and blocked by flufenamate, ATP4− and Gd3+. All these properties correspond well to those of TRPM4 channels. Calcium imaging of functional slices revealed rhythmic transients in small clusters of neurons present in a network. Calcium transients in the soma were preceded by the waves in dendrites which were dependent on mGluR activation. Initiation and propagation of waves required calcium influx and calcium release from internal stores. Calcium waves activated TPRM4-like channels in the soma and promoted generation of inspiratory bursts. Simulations of activity of neurons communicated via dendritic calcium waves showed emerging activity within neuronal clusters and its synchronization between the clusters. The experimental and theoretical data provide a subcellular basis for a recently proposed group-pacemaker hypothesis and describe a novel mechanism of rhythm generation in neuronal networks. PMID:18308826

  20. Synthesis and antimicrobial evaluation of nitazoxanide-based analogues: identification of selective and broad spectrum activity.

    PubMed

    Ballard, T Eric; Wang, Xia; Olekhnovich, Igor; Koerner, Taylor; Seymour, Craig; Salamoun, Joseph; Warthan, Michelle; Hoffman, Paul S; Macdonald, Timothy L

    2011-02-01

    A library composed of nitazoxanide-based analogues was synthesized and assayed for increased antibacterial efficacy against the pyruvate-ferredoxin oxidoreductase (PFOR) using microorganisms Helicobacter pylori, Campylobacter jejuni and Clostridium difficile. Derivatives were found to recapitulate and improve activity against these organisms and select analogues were tested for their ability to disrupt the PFOR enzyme directly. The library was also screened for activity against staphylococci and resulted in the identification of analogues capable of inhibiting both staphylococci and all PFOR organisms at low micromolar minimum inhibitory concentrations with low toxicity to human foreskin cells. PMID:21275058

  1. The Synthesis of Active Metabolites and Analogues of Vitamin D3

    NASA Astrophysics Data System (ADS)

    Yakhimovich, R. I.

    1980-04-01

    The literature date on the synthesis of the active metabolites and analogues of vitamin D3 (cholecalciferol), which play an important role in regulating the homeostatis of calcium in the organism, are reviewed. The bibliography includes 150 references.

  2. Antimicrobial activity of antihypertensive food-derived peptides and selected alanine analogues.

    PubMed

    McClean, Stephen; Beggs, Louise B; Welch, Robert W

    2014-03-01

    This study evaluated four food-derived peptides with known antihypertensive activities for antimicrobial activity against pathogenic microorganisms, and assessed structure-function relationships using alanine analogues. The peptides (EVSLNSGYY, barley; PGTAVFK, soybean; TTMPLW, α-casein; VHLPP, α-zein) and the six alanine substitution peptides of PGTAVFK were synthesised, characterised and evaluated for antimicrobial activity using the bacteria, Escherichia coli, Staphylococcus aureus, and Micrococcus luteus and the yeast, Candida albicans. The peptides TTMPLW and PGTAVFK inhibited growth of all four microorganisms tested, with activities of a similar order of magnitude to ampicillin and ethanol controls. EVSLNSGYY inhibited the growth of the bacteria, but VHLPP showed no antimicrobial activity. The alanine analogue, PGAAVFK showed the highest overall antimicrobial activity and PGTAVFA showed no activity; overall, the activities of the analogues were consistent with their structures. Some peptides with antihypertensive activity also show antimicrobial activity, suggesting that food-derived peptides may exert beneficial effects via a number of mechanisms.

  3. Glutamate excitotoxicity and Ca2+-regulation of respiration: Role of the Ca2+ activated mitochondrial transporters (CaMCs).

    PubMed

    Rueda, Carlos B; Llorente-Folch, Irene; Traba, Javier; Amigo, Ignacio; Gonzalez-Sanchez, Paloma; Contreras, Laura; Juaristi, Inés; Martinez-Valero, Paula; Pardo, Beatriz; Del Arco, Araceli; Satrustegui, Jorgina

    2016-08-01

    Glutamate elicits Ca(2+) signals and workloads that regulate neuronal fate both in physiological and pathological circumstances. Oxidative phosphorylation is required in order to respond to the metabolic challenge caused by glutamate. In response to physiological glutamate signals, cytosolic Ca(2+) activates respiration by stimulation of the NADH malate-aspartate shuttle through Ca(2+)-binding to the mitochondrial aspartate/glutamate carrier (Aralar/AGC1/Slc25a12), and by stimulation of adenine nucleotide uptake through Ca(2+) binding to the mitochondrial ATP-Mg/Pi carrier (SCaMC-3/Slc25a23). In addition, after Ca(2+) entry into the matrix through the mitochondrial Ca(2+) uniporter (MCU), it activates mitochondrial dehydrogenases. In response to pathological glutamate stimulation during excitotoxicity, Ca(2+) overload, reactive oxygen species (ROS), mitochondrial dysfunction and delayed Ca(2+) deregulation (DCD) lead to neuronal death. Glutamate-induced respiratory stimulation is rapidly inactivated through a mechanism involving Poly (ADP-ribose) Polymerase-1 (PARP-1) activation, consumption of cytosolic NAD(+), a decrease in matrix ATP and restricted substrate supply. Glutamate-induced Ca(2+)-activation of SCaMC-3 imports adenine nucleotides into mitochondria, counteracting the depletion of matrix ATP and the impaired respiration, while Aralar-dependent lactate metabolism prevents substrate exhaustion. A second mechanism induced by excitotoxic glutamate is permeability transition pore (PTP) opening, which critically depends on ROS production and matrix Ca(2+) entry through the MCU. By increasing matrix content of adenine nucleotides, SCaMC-3 activity protects against glutamate-induced PTP opening and lowers matrix free Ca(2+), resulting in protracted appearance of DCD and protection against excitotoxicity in vitro and in vivo, while the lack of lactate protection during in vivo excitotoxicity explains increased vulnerability to kainite-induced toxicity in Aralar

  4. Synthesis and antiproliferative activity of glutamic acid-based dipeptides.

    PubMed

    Silveira-Dorta, Gastón; Martín, Víctor S; Padrón, José M

    2015-08-01

    A small and focused library of 22 dipeptides derived from N,N-dibenzylglutamic acid α- and γ-benzyl esters was prepared in a straightforward manner. The evaluation of the antiproliferative activity in the human solid tumor cell lines HBL-100 (breast), HeLa (cervix), SW1573 (non-small cell lung), T-47D (breast), and WiDr (colon) provided γ-glutamyl methionine (GI50 = 6.0-41 μM) and α-glutamyl proline (GI50 = 7.5-18 μM) as lead compounds. In particular, glutamyl serine and glutamyl proline dipeptides were more active in the resistant cancer cell line WiDr than the conventional anticancer drugs cisplatin and etoposide. Glutamyl tryptophan dipeptides did not affect cell growth of HBL-100, while in T-47D cells, proliferation was inhibited. This result might be attributed to the inhibition of the ATB(0,+) transporter.

  5. Synthesis and antiproliferative activity of glutamic acid-based dipeptides.

    PubMed

    Silveira-Dorta, Gastón; Martín, Víctor S; Padrón, José M

    2015-08-01

    A small and focused library of 22 dipeptides derived from N,N-dibenzylglutamic acid α- and γ-benzyl esters was prepared in a straightforward manner. The evaluation of the antiproliferative activity in the human solid tumor cell lines HBL-100 (breast), HeLa (cervix), SW1573 (non-small cell lung), T-47D (breast), and WiDr (colon) provided γ-glutamyl methionine (GI50 = 6.0-41 μM) and α-glutamyl proline (GI50 = 7.5-18 μM) as lead compounds. In particular, glutamyl serine and glutamyl proline dipeptides were more active in the resistant cancer cell line WiDr than the conventional anticancer drugs cisplatin and etoposide. Glutamyl tryptophan dipeptides did not affect cell growth of HBL-100, while in T-47D cells, proliferation was inhibited. This result might be attributed to the inhibition of the ATB(0,+) transporter. PMID:25900811

  6. CPG2 Recruits Endophilin B2 to the Cytoskeleton for Activity-Dependent Endocytosis of Synaptic Glutamate Receptors.

    PubMed

    Loebrich, Sven; Benoit, Marc Robert; Konopka, Jaclyn Aleksandra; Cottrell, Jeffrey Richard; Gibson, Joanne; Nedivi, Elly

    2016-02-01

    Internalization of glutamate receptors at the postsynaptic membrane via clathrin-mediated endocytosis (CME) is a key mechanism for regulating synaptic strength. A role for the F-actin cytoskeleton in CME is well established, and recently, PKA-dependent association of candidate plasticity gene 2 (CPG2) with the spine-cytoskeleton has been shown to mediate synaptic glutamate receptor internalization. Yet, how the endocytic machinery is physically coupled to the actin cytoskeleton to facilitate glutamate receptor internalization has not been demonstrated. Moreover, there has been no distinction of endocytic-machinery components that are specific to activity-dependent versus constitutive glutamate receptor internalization. Here, we show that CPG2, through a direct physical interaction, recruits endophilin B2 (EndoB2) to F-actin, thus anchoring the endocytic machinery to the spine cytoskeleton and facilitating glutamate receptor internalization. Regulation of CPG2 binding to the actin cytoskeleton by protein kinase A directly impacts recruitment of EndoB2 and clathrin. Specific disruption of EndoB2 or the CPG2-EndoB2 interaction impairs activity-dependent, but not constitutive, internalization of both NMDA- and AMPA-type glutamate receptors. These results demonstrate that, through direct interactions with F-actin and EndoB2, CPG2 physically bridges the spine cytoskeleton and the endocytic machinery, and this tripartite association is critical specifically for activity-dependent CME of synaptic glutamate receptors. PMID:26776730

  7. Modulation of pineal melatonin synthesis by glutamate involves paracrine interactions between pinealocytes and astrocytes through NF-κB activation.

    PubMed

    Villela, Darine; Atherino, Victoria Fairbanks; Lima, Larissa de Sá; Moutinho, Anderson Augusto; do Amaral, Fernanda Gaspar; Peres, Rafael; Martins de Lima, Thais; Torrão, Andréa da Silva; Cipolla-Neto, José; Scavone, Cristóforo; Afeche, Solange Castro

    2013-01-01

    The glutamatergic modulation of melatonin synthesis is well known, along with the importance of astrocytes in mediating glutamatergic signaling in the central nervous system. Pinealocytes and astrocytes are the main cell types in the pineal gland. The objective of this work was to investigate the interactions between astrocytes and pinealocytes as a part of the glutamate inhibitory effect on melatonin synthesis. Rat pinealocytes isolated or in coculture with astrocytes were incubated with glutamate in the presence of norepinephrine, and the melatonin content, was quantified. The expression of glutamate receptors, the intracellular calcium content and the NF- κ B activation were analyzed in astrocytes and pinealocytes. TNF- α 's possible mediation of the effect of glutamate was also investigated. The results showed that glutamate's inhibitory effect on melatonin synthesis involves interactions between astrocytes and pinealocytes, possibly through the release of TNF- α . Moreover, the activation of the astrocytic NF- κ B seems to be a necessary step. In astrocytes and pinealocytes, AMPA, NMDA, and group I metabotropic glutamate receptors were observed, as well as the intracellular calcium elevation. In conclusion, there is evidence that the modulation of melatonin synthesis by glutamate involves paracrine interactions between pinealocytes and astrocytes through the activation of the astrocytic NF- κ B transcription factor and possibly by subsequent TNF- α release.

  8. Glutamate protects against Ca(2+) paradox-induced injury and inhibits calpain activity in isolated rat hearts.

    PubMed

    Zhang, Jian-Ying; Kong, Ling-Heng; Lai, Dong; Jin, Zhen-Xiao; Gu, Xiao-Ming; Zhou, Jing-Jun

    2016-10-01

    This study determined the effects of glutamate on the Ca(2+) paradoxical heart, which is a model for Ca(2+) overload-induced injury during myocardial ischaemia and reperfusion, and evaluated its effect on a known mediator of injury, calpain. An isolated rat heart was retrogradely perfused in a Langendorff apparatus. Ca(2+) paradox was elicited via perfusion with a Ca(2+) -free Krebs-Henseleit (KH) solution for 3 minutes followed by Ca(2+) -containing normal KH solution for 30 minutes. The Ca(2+) paradoxical heart exhibited almost no viable tissue on triphenyltetrazolium chloride staining and markedly increased LDH release, caspase-3 activity, cytosolic cytochrome c content, and apoptotic index. These hearts also displayed significantly increased LVEDP and a disappearance of LVDP. Glutamate (5 and 20 mmol/L) significantly alleviated Ca(2+) paradox-induced injury. In contrast, 20 mmol/L mannitol had no effect on Ca(2+) paradox. Ca(2+) paradox significantly increased the extent of the translocation of μ-calpain to the sarcolemmal membrane and the proteolysis of α-fodrin, which suggests calpain activation. Glutamate also blocked these effects. A non-selective inhibitor of glutamate transporters, dl-TBOA (10 μmol/L), had no effect on control hearts, but it reversed glutamate-induced cardioprotection and reduction in calpain activity. Glutamate treatment significantly increased intracellular glutamate content in the Ca(2+) paradoxical heart, which was also blocked by dl-TBOA. We conclude that glutamate protects the heart against Ca(2+) overload-induced injury via glutamate transporters, and the inhibition of calpain activity is involved in this process.

  9. Mammalian folylpoly-. gamma. -glutamate synthetase. 4. In vitro and in vivo metabolism of folates and analogues and regulation of folate homeostasis

    SciTech Connect

    Cook, J.D.; Cichowicz, D.J.; George, S.; Lawler, Ann; Shane, B.

    1987-01-27

    The regulation of folate and folate analogue metabolism was studied in vitro by using purified hog liver folylpolyglutamate synthetase as a model system and in vivo in cultured mammalian cells. The types of folylpolyglutamates that accumulate in vivo in hog liver, and changes in cellular folate levels and folylpolyglutamate distributions caused by physiological and nutritional factors such as changes in growth rates and methionine, folate, and vitamin B/sub 12/ status, can be mimicked in vitro by using purified enzyme. (/sup 3/H)Folylpolyglutamate distributions can be explained solely in terms of the substrate specificity of folylpolyglutamate synthetase and can be modeled by using kinetic parameters obtained with purified enzyme. Low levels of folylpolyglutamate synthetase activity are normally required for the cellular metabolism of folates to retainable polyglutamate forms, and consequently folate retention and concentration, while higher levels of activity are required for the synthesis of the long chain length derivatives that are found in mammalian tissues. The synthesis of very long chain derivatives, which requires tetrahydrofolate polyglutamates as substrates, is a very slow process in vivo. The slow metabolism of 5-methyltetrahydrofolate to retainable polyglutamate forms causes the decreased tissue retention of folate in B/sub 12/ deficiency. Although cellular folylpolyglutamate distributions change in response to nutritional and physiological modulations, it is unlikely that these changes play a regulatory role in one-carbon metabolism as folate distributions respond only slowly.

  10. Oligomers of Amyloid β Prevent Physiological Activation of the Cellular Prion Protein-Metabotropic Glutamate Receptor 5 Complex by Glutamate in Alzheimer Disease.

    PubMed

    Haas, Laura T; Strittmatter, Stephen M

    2016-08-12

    The dysfunction and loss of synapses in Alzheimer disease are central to dementia symptoms. We have recently demonstrated that pathological Amyloid β oligomer (Aβo) regulates the association between intracellular protein mediators and the synaptic receptor complex composed of cellular prion protein (PrP(C)) and metabotropic glutamate receptor 5 (mGluR5). Here we sought to determine whether Aβo alters the physiological signaling of the PrP(C)-mGluR5 complex upon glutamate activation. We provide evidence that acute exposure to Aβo as well as chronic expression of familial Alzheimer disease mutant transgenes in model mice prevents protein-protein interaction changes of the complex induced by the glutamate analog 3,5-dihydroxyphenylglycine. We further show that 3,5-dihydroxyphenylglycine triggers the phosphorylation and activation of protein-tyrosine kinase 2-β (PTK2B, also referred to as Pyk2) and of calcium/calmodulin-dependent protein kinase II in wild-type brain slices but not in Alzheimer disease transgenic brain slices or wild-type slices incubated with Aβo. This study further distinguishes two separate Aβo-dependent signaling cascades, one dependent on extracellular Ca(2+) and Fyn kinase activation and the other dependent on the release of Ca(2+) from intracellular stores. Thus, Aβo triggers multiple distinct PrP(C)-mGluR5-dependent events implicated in neurodegeneration and dementia. We propose that targeting the PrP(C)-mGluR5 complex will reverse aberrant Aβo-triggered states of the complex to allow physiological fluctuations of glutamate signaling.

  11. Synthesis of p-aminophenyl aryl H-phosphinic acids and esters via cross-coupling reactions: elaboration to phosphinic acid pseudopeptide analogues of pteroyl glutamic acid and related antifolates.

    PubMed

    Yang, Yonghong; Coward, James K

    2007-07-20

    The synthesis of suitably protected p-aminophenyl H-phosphinic acids and esters from the corresponding para-substituted aryl halides has been accomplished via the Pd-catalyzed cross-coupling reaction of anilinium hypophosphite, either in the absence or presence of a tetraalkyl orthosilicate, to provide the free H-phosphinic acid or the corresponding ester, respectively. Subsequent conjugate addition of either a PIII species or phosphorus anion, generated in situ from either the free H-phosphinic acid or ester, to a 2-methylene glutaric acid ester provided the aryl phosphinic acid analogue of p-aminobenzoyl glutamic acid. Alkylation of these suitably protected p-aminophenyl phosphinic acid esters with a 6-(bromomethyl)pteridine or the corresponding (bromomethyl)pyridopyrmidine, followed by hydrolytic removal of protecting groups, provided the target aryl phosphinic acid analogues of folic acid and related antifolates. Alternatively, for the synthesis of the folate or 5-deazafolate analogues on a slightly larger scale, reductive amination with either N2-acetyl or N2-pivaloyl-6-formylpterin or the corresponding formylpyridopyrmidine and the same suitably protected p-aminophenyl phosphinic acid esters, followed by removal of protecting groups, is preferred. In the course of this research, it was observed that the nucleophilicity of both the aniline nitrogen and various PIII species derived from p-aminophenyl phosphinic acid derivatives is significantly reduced compared to that of the unsubstituted counterpart. PMID:17602593

  12. Synthesis and biological activity of new quinoxaline antibiotics of echinomycin analogues.

    PubMed

    Kim, Yun Bong; Kim, Yong Hae; Park, Ju Youn; Kim, Soo Kie

    2004-01-19

    Novel quinoxaline antibiotics having the methylenedithioether bridge as an analogue of echinomycin have been synthesized by insertion of methylene moiety between -S-S- bond. The compound 1a shows remarkable cytotoxicities against human tumor various cell lines, and is active VRE (vancomycin-resistant enterococci) within MIC range 0.5-8 microg/mL. According to the eukaryotic or prokaryotic data, 1a might be a first analogue to replace echinomycin.

  13. Pena Blanca Natural Analogue Project: Summary of activities

    SciTech Connect

    Levy, S.; Goldstein, S.; Dobson, P.F.; Goodell, P.; Ku, T.-L.; Abdel-Fattah, A.; Saulnier, G.; Fayek, M.; de la Garza, R.

    2011-02-01

    The inactive Nopal I uranium mine in silicic tuff north of Chihuahua City, Chihuahua, Mexico, was studied as a natural analogue for an underground nuclear-waste repository in the unsaturated zone. Site stratigraphy was confirmed from new drill cores. Data from site studies include chemical and isotopic compositions of saturated- and unsaturated-zone waters. A partial geochronology of uranium enrichment and mineralization was established. Evidence pertinent to uranium-series transport in the soil zone and changing redox conditions was collected. The investigations contributed to preliminary, scoping-level performance assessment modeling.

  14. Novel spirobicyclic artemisinin analogues (artemalogues): Synthesis and antitumor activities.

    PubMed

    Liu, Gang; Song, Shanshan; Shu, Shiqi; Miao, Zehong; Zhang, Ao; Ding, Chunyong

    2015-10-20

    The sesquiterpene lactone framework of artemisinin was used as a drug repositioning prototype for the development of novel antitumor drugs. Several series of novel artemisinin analogues (artemalogues) were designed and synthesized through 1,3-dipolar cycloaddition of artemisitene with nitrile oxides or nitrones. The isoxazolidine-containing spirobicyclic artemalogue 11b turns out to be the most potent with low micromolar IC₅₀ values against all three tumor cells, which were at least 4- to 14-fold more potent than the parent artemisinin. PMID:26318055

  15. Pena blanca natural analogue project: summary of activities

    SciTech Connect

    Levy, Schon S; Goldstein, Steven J; Abdel - Fattah, Amr I

    2010-12-08

    The inactive Nopal I uranium mine in silicic tuff north of Chihuahua City, Chihuahua, Mexico, was studied as a natural analogue for an underground nuclear-waste repository in the unsaturated zone. Site stratigraphy was confirmed from new drill core. Datafrom site studies include chemical and isotopic compositions of saturated- and unsaturated-zone waters. A partial geochronology of uranium enrichment and mineralization was established. Evidence pertinent to uranium-series transport in the soil zone and changing redox conditions was collected. The investigations contributed to preliminary, scoping-level performance assessment modeling.

  16. Guest-Activated Forbidden Tilts in a Molecular Perovskite Analogue.

    PubMed

    Duyker, Samuel G; Hill, Joshua A; Howard, Christopher J; Goodwin, Andrew L

    2016-09-01

    The manipulation of distortions in perovskite structures is critical to tailoring the properties of these materials for a variety of applications. Here we demonstrate a violation of established octahedral tilt rules in the double perovskite analogue (NH4)2SrFe(CN)6·2H2O. The forbidden tilt pattern we observe arises through coupling to hydration-driven Jahn-Teller-like distortions of the Sr coordination environment. Access to novel distortion mechanisms and the ability to switch these distortions on and off through chemical modification fundamentally expands the toolbox of techniques available for engineering symmetry-breaking processes in solid materials. PMID:27533044

  17. Postsynaptic actin regulates active zone spacing and glutamate receptor apposition at the Drosophila neuromuscular junction.

    PubMed

    Blunk, Aline D; Akbergenova, Yulia; Cho, Richard W; Lee, Jihye; Walldorf, Uwe; Xu, Ke; Zhong, Guisheng; Zhuang, Xiaowei; Littleton, J Troy

    2014-07-01

    Synaptic communication requires precise alignment of presynaptic active zones with postsynaptic receptors to enable rapid and efficient neurotransmitter release. How transsynaptic signaling between connected partners organizes this synaptic apparatus is poorly understood. To further define the mechanisms that mediate synapse assembly, we carried out a chemical mutagenesis screen in Drosophila to identify mutants defective in the alignment of active zones with postsynaptic glutamate receptor fields at the larval neuromuscular junction. From this screen we identified a mutation in Actin 57B that disrupted synaptic morphology and presynaptic active zone organization. Actin 57B, one of six actin genes in Drosophila, is expressed within the postsynaptic bodywall musculature. The isolated allele, act(E84K), harbors a point mutation in a highly conserved glutamate residue in subdomain 1 that binds members of the Calponin Homology protein family, including spectrin. Homozygous act(E84K) mutants show impaired alignment and spacing of presynaptic active zones, as well as defects in apposition of active zones to postsynaptic glutamate receptor fields. act(E84K) mutants have disrupted postsynaptic actin networks surrounding presynaptic boutons, with the formation of aberrant actin swirls previously observed following disruption of postsynaptic spectrin. Consistent with a disruption of the postsynaptic actin cytoskeleton, spectrin, adducin and the PSD-95 homolog Discs-Large are all mislocalized in act(E84K) mutants. Genetic interactions between act(E84K) and neurexin mutants suggest that the postsynaptic actin cytoskeleton may function together with the Neurexin-Neuroligin transsynaptic signaling complex to mediate normal synapse development and presynaptic active zone organization.

  18. Synthetic analogues of the microtubule-stabilizing agent (+)-discodermolide: preparation and biological activity.

    PubMed

    Gunasekera, Sarath P; Mickel, Stuart J; Daeffler, Robert; Niederer, Daniel; Wright, Amy E; Linley, Patricia; Pitts, Tara

    2004-05-01

    A series of seven synthetic discodermolide analogues 2-8, which are minor side products generated during the final stages in the synthesis of (+)-discodermolide (1), have been purified and evaluated for in vitro cytotoxicity against A549, P388, MFC-7, NCI/ADR, PANC-1, and VERO cell lines. These synthetic analogues showed a significant variation of cytotoxicity and confirmed the importance of the C-7 hydroxy through C-17 hydroxy molecular fragment for potency. Specifically, these analogues suggested the relevance of the C-11 hydroxyl group, the C-13 double bond, and the C-16 (S) stereochemistry for the potency of (+)-discodermolide. The preparation, purification, structure elucidation, and biological activity of these new analogues are described.

  19. Designed, synthetically accessible bryostatin analogues potently induce activation of latent HIV reservoirs in vitro

    NASA Astrophysics Data System (ADS)

    Dechristopher, Brian A.; Loy, Brian A.; Marsden, Matthew D.; Schrier, Adam J.; Zack, Jerome A.; Wender, Paul A.

    2012-09-01

    Bryostatin is a unique lead in the development of potentially transformative therapies for cancer, Alzheimer's disease and the eradication of HIV/AIDS. However, the clinical use of bryostatin has been hampered by its limited supply, difficulties in accessing clinically relevant derivatives, and side effects. Here, we address these problems through the step-economical syntheses of seven members of a new family of designed bryostatin analogues using a highly convergent Prins-macrocyclization strategy. We also demonstrate for the first time that such analogues effectively induce latent HIV activation in vitro with potencies similar to or better than bryostatin. Significantly, these analogues are up to 1,000-fold more potent in inducing latent HIV expression than prostratin, the current clinical candidate for latent virus induction. This study provides the first demonstration that designed, synthetically accessible bryostatin analogues could serve as superior candidates for the eradication of HIV/AIDS through induction of latent viral reservoirs in conjunction with current antiretroviral therapy.

  20. Structure-activity relationship studies on cholecystokinin: Analogues with partial agonist activity

    SciTech Connect

    Galas, M.C.; Lignon, M.F.; Rodriguez, M.; Mendre, C.; Fulcrand, P.; Laur, J.; Martinez, J. )

    1988-02-01

    In the present study, hepta- and octapeptide analogues of the C-terminal part of cholecystokinin, modified on the C-terminal phenylalanine residue, were synthesized. CCK analogues were prepared in which the peptide bond between aspartic acid and phenylalanine had or had not been modified and were lacking the C-terminal primary amide function. These CCK derivatives were able to cause full stimulation of amylase release from rat pancreatic acini but without a decrease in amylase release at supramaximal concentrations. There was a close relationship between the abilities of these derivatives to stimulate amylase release and their abilities to inhibit binding of {sup 125}I-BH-CCK-9 to CCK receptors on rat and guinea pig pancreatic acini. These CCK analogues were also able to recognize the guinea pig brain CCK receptors, some of them being particularly potent. The findings indicate that the aromatic ring of phenylalanine is important for the binding to brain and pancreatic CCK receptors, whereas the C-terminal primary amide function is not essential for the binding to pancreatic CCK receptors but is crucial for biological activity of rat pancreatic acini.

  1. Cinnabarinic acid, an endogenous metabolite of the kynurenine pathway, activates type 4 metabotropic glutamate receptors.

    PubMed

    Fazio, F; Lionetto, L; Molinaro, G; Bertrand, H O; Acher, F; Ngomba, R T; Notartomaso, S; Curini, M; Rosati, O; Scarselli, P; Di Marco, R; Battaglia, G; Bruno, V; Simmaco, M; Pin, J P; Nicoletti, F; Goudet, C

    2012-05-01

    Cinnabarinic acid is an endogenous metabolite of the kynurenine pathway that meets the structural requirements to interact with glutamate receptors. We found that cinnabarinic acid acts as a partial agonist of type 4 metabotropic glutamate (mGlu4) receptors, with no activity at other mGlu receptor subtypes. We also tested the activity of cinnabarinic acid on native mGlu4 receptors by examining 1) the inhibition of cAMP formation in cultured cerebellar granule cells; 2) protection against excitotoxic neuronal death in mixed cultures of cortical cells; and 3) protection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine toxicity in mice after local infusion into the external globus pallidus. In all these models, cinnabarinic acid behaved similarly to conventional mGlu4 receptor agonists, and, at least in cultured neurons, the action of low concentrations of cinnabarinic acid was largely attenuated by genetic deletion of mGlu4 receptors. However, high concentrations of cinnabarinic acid were still active in the absence of mGlu4 receptors, suggesting that the compound may have off-target effects. Mutagenesis and molecular modeling experiments showed that cinnabarinic acid acts as an orthosteric agonist interacting with residues of the glutamate binding pocket of mGlu4. Accordingly, cinnabarinic acid did not activate truncated mGlu4 receptors lacking the N-terminal Venus-flytrap domain, as opposed to the mGlu4 receptor enhancer, N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC). Finally, we could detect endogenous cinnabarinic acid in brain tissue and peripheral organs by high-performance liquid chromatography-tandem mass spectrometry analysis. Levels increased substantially during inflammation induced by lipopolysaccharide. We conclude that cinnabarinic acid is a novel endogenous orthosteric agonist of mGlu4 receptors endowed with neuroprotective activity. PMID:22311707

  2. Synthesis and Structure activity relationships of EGCG Analogues, A Recently Identified Hsp90 Inhibitor

    PubMed Central

    Khandelwal, Anuj; Hall, Jessica

    2014-01-01

    Epigallocatechin-3-gallate (EGCG), the principal polyphenol isolated from green tea, was recently shown to inhibit Hsp90, however structure-activity relationships for this natural product have not yet been produced. Herein, we report the synthesis and biological evaluation of EGCG analogues to establish structure-activity relationships between EGCG and Hsp90. All four rings as well as the linker connecting the C- and the D-rings were systematically investigated, which led to the discovery of compounds that inhibit Hs90 and display improvement in efficacy over EGCG. Anti-proliferative activity of all the analogues was determined against MCF-7 and SKBr3 cell lines and Hsp90 inhibitory activity of four most potent analogues was further evaluated by western blot analyses and degradation of Hsp90-dependent client proteins. Prenyl substituted aryl ester of 3,5-dihydroxychroman-3-ol ring system was identified as novel scaffold that exhibit Hsp90 inhibitory activity. PMID:23834230

  3. Design, synthesis and exploring the quantitative structure-activity relationship of some antioxidant flavonoid analogues.

    PubMed

    Das, Sreeparna; Mitra, Indrani; Batuta, Shaikh; Niharul Alam, Md; Roy, Kunal; Begum, Naznin Ara

    2014-11-01

    A series of flavonoid analogues were synthesized and screened for the in vitro antioxidant activity through their ability to quench 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. The activity of these compounds, measured in comparison to the well-known standard antioxidants (29-32), their precursors (38-42) and other bioactive moieties (38-42) resembling partially the flavone skeleton was analyzed further to develop Quantitative Structure-Activity Relationship (QSAR) models using the Genetic Function Approximation (GFA) technique. Based on the essential structural requirements predicted by the QSAR models, some analogues were designed, synthesized and tested for activity. The predicted and experimental activities of these compounds were well correlated. Flavone analogue 20 was found to be the most potent antioxidant.

  4. Synthesis and structure-activity relationships of EGCG analogues, a recently identified Hsp90 inhibitor.

    PubMed

    Khandelwal, Anuj; Hall, Jessica A; Blagg, Brian S J

    2013-08-16

    Epigallocatechin-3-gallate (EGCG), the principal polyphenol isolated from green tea, was recently shown to inhibit Hsp90; however, structure-activity relationships for this natural product have not yet been produced. Herein, we report the synthesis and biological evaluation of EGCG analogues to establish structure-activity relationships between EGCG and Hsp90. All four rings as well as the linker connecting the C- and the D-rings were systematically investigated, which led to the discovery of compounds that inhibit Hs90 and display improvement in efficacy over EGCG. Antiproliferative activity of all the analogues was determined against MCF-7 and SKBr3 cell lines and Hsp90 inhibitory activity of the four most potent analogues was further evaluated by Western blot analyses and degradation of Hsp90-dependent client proteins. The prenyl-substituted aryl ester of 3,5-dihydroxychroman-3-ol ring system was identified as a novel scaffold that exhibits Hsp90 inhibitory activity. PMID:23834230

  5. Physical location of the site for N-acetyl-L-glutamate, the allosteric activator of carbamoyl phosphate synthetase, in the 20-kilodalton COOH-terminal domain.

    PubMed

    Rodriguez-Aparicio, L B; Guadalajara, A M; Rubio, V

    1989-04-01

    Mammalian liver mitochondrial carbamoyl phosphate synthetase, a polypeptide of 160 kDa, is activated allosterically by N-acetyl-L-glutamate. The analogue of this activator N-(chloroacetyl)-L-[14C]glutamate has been found to serve as a photoaffinity label for this enzyme. The specificity was demonstrated by the drastic reduction in the radioactivity bound to the protein when (a) an excess of unlabeled acetylglutamate was present during the irradiation and (b) the enzyme was replaced by pyruvate kinase, an enzyme that is not affected by acetylglutamate. The labeling was due to the photoactivation of the chloroacetyl group since there was no labeling under equal conditions with acetyl[14C]glutamate. To localize the binding site, limited proteolysis was used. Trypsin cleaves carbamoyl phosphate synthetase into complementary NH2- and COOH-terminal fragments of about 140 and 20 kDa, respectively [Powers-Lee, S. G., & Corina, K. (1986) J. Biol. Chem. 261, 15349-15352], but only the latter was found to be labeled. Similarly, of the various fragments generated by elastase, only two, of 20 and 120 kDa, contain the COOH terminus [see Powers-Lee and Corina (1986) above] and were found to be labeled. Thus, the binding site for acetylglutamate is within 20 kDa from the COOH terminus. This excludes the possibility that the acetylglutamate binding site evolved from an ancestral substrate site for glutamine: this substrate binds to the small subunit of the Escherichia coli enzyme, which is homologous to the NH2-terminal domain of the rat liver enzyme. Exhaustive tryptic digestion of photolabeled carbamoyl phosphate synthetase yielded a single radioactive peak, suggesting that the labeling is restricted to a single minimal tryptic peptide. PMID:2742825

  6. Activation of glutamate transport evokes rapid glutamine release from perisynaptic astrocytes

    PubMed Central

    Uwechue, Nneka M; Marx, Mari-Carmen; Chevy, Quentin; Billups, Brian

    2012-01-01

    Stimulation of astrocytes by neuronal activity and the subsequent release of neuromodulators is thought to be an important regulator of synaptic communication. In this study we show that astrocytes juxtaposed to the glutamatergic calyx of Held synapse in the rat medial nucleus of the trapezoid body (MNTB) are stimulated by the activation of glutamate transporters and consequently release glutamine on a very rapid timescale. MNTB principal neurones express electrogenic system A glutamine transporters, and were exploited as glutamine sensors in this study. By simultaneous whole-cell voltage clamping astrocytes and neighbouring MNTB neurones in brainstem slices, we show that application of the excitatory amino acid transporter (EAAT) substrate d-aspartate stimulates astrocytes to rapidly release glutamine, which is detected by nearby MNTB neurones. This release is significantly reduced by the toxins l-methionine sulfoximine and fluoroacetate, which reduce glutamine concentrations specifically in glial cells. Similarly, glutamine release was also inhibited by localised inactivation of EAATs in individual astrocytes, using internal dl-threo-β-benzyloxyaspartic acid (TBOA) or dissipating the driving force by modifying the patch-pipette solution. These results demonstrate that astrocytes adjacent to glutamatergic synapses can release glutamine in a temporally precise, controlled manner in response to glial glutamate transporter activation. Since glutamine can be used by neurones as a precursor for glutamate and GABA synthesis, this represents a potential feedback mechanism by which astrocytes can respond to synaptic activation and react in a way that sustains or enhances further communication. This would therefore represent an additional manifestation of the tripartite relationship between synapses and astrocytes. PMID:22411007

  7. Hydrokinetic activity of secretion and secretin analogues, modified in the N-terminal sequence, and of vasoactive intestinal peptide in the dog pancreas.

    PubMed

    Lehnert, P; Forell, M M; Jaeger, E; Moroder, L; Wünsch, E

    1981-01-01

    In the dog pancreas in vivo, the biological activity of secretin and vasoactive intestinal peptide was compared to that of secretin analogues modified in their N-terminal hexapeptide and to X-secretion (alpha, beta-Asp3-secretin) and Y-secretin (a conversion product of X-secretin consisting of about 15% secretin and 85% beta-Asp3-secretin). Replacement of Asp3 by glutamic acid reduced secretin activity markedly. Replacement by neutral amino acids abolished the activity nearly completely. alpha, beta-Asp3-secretin and beta-Asp3-secretin appeared to be ineffective. The results indicate that the free beta-carboxy group of the side chain of the Asp3 residue of the secretin molecule is of decisive importance for hydrokinetic action.

  8. Hydrokinetic activity of secretion and secretin analogues, modified in the N-terminal sequence, and of vasoactive intestinal peptide in the dog pancreas.

    PubMed

    Lehnert, P; Forell, M M; Jaeger, E; Moroder, L; Wünsch, E

    1981-01-01

    In the dog pancreas in vivo, the biological activity of secretin and vasoactive intestinal peptide was compared to that of secretin analogues modified in their N-terminal hexapeptide and to X-secretion (alpha, beta-Asp3-secretin) and Y-secretin (a conversion product of X-secretin consisting of about 15% secretin and 85% beta-Asp3-secretin). Replacement of Asp3 by glutamic acid reduced secretin activity markedly. Replacement by neutral amino acids abolished the activity nearly completely. alpha, beta-Asp3-secretin and beta-Asp3-secretin appeared to be ineffective. The results indicate that the free beta-carboxy group of the side chain of the Asp3 residue of the secretin molecule is of decisive importance for hydrokinetic action. PMID:7274610

  9. Teratogen metabolism: activation of thalidomide and thalidomide analogues to products that inhibit the attachment of cells to concanavalin A coated plastic surfaces. Revised version

    SciTech Connect

    Braun, A.G.; Weinreb, S.L.

    1982-01-01

    Thalidomide metabolites inhibit the attachment of tumor cells to concanavalin A coated polyethylene surfaces. Thalidomide, itself, is non-inhibitory. Thalidomide activation to inhibitory products requires hepatic microsomes, an NADPH generating system and molecular oxygen. Production of inhibitory metabolites is unaffected by either epoxide hydrolase or TCPO, an inhibitor of epoxide hydrolase endogenous to hepatic S9 fraction. Therefore the attachment inhibitor is probably not an arene oxide. Inhibition is not accompanied by cytotoxicity as judged by trypan blue exclusion. Although uninduced hepatic microsomes from mice, rats and dogs have similar ability to activate thalidomide, microsomes from Aroclor 1254 induced rats are relatively inactive in the system. Inhibitory metabolites can be generated from the thalidomide analogues EM8, EM12, EM16, EM87, EM136, EM255, E350, phthalimide, phthalimido-phthalimide, indan, 1-indanone and 1,3-indandione. Glutarimide, glutamic acid and phthalic acid do not activate to inhibitory products.

  10. Design, structure activity relationship, cytotoxicity and evaluation of antioxidant activity of curcumin derivatives/analogues.

    PubMed

    Sahu, Pramod K

    2016-10-01

    New fourteen 3,4-dihydropyrimidine derivatives/analogues of curcumin (2a-2n) were designed, synthesized and biologically evaluated for their cytotoxicity and antioxidant activity. Cytotoxicity effect has been evaluated against three cell lines HeLa, HCT-116 and QG-56 by MTT assay method. From SAR study, it has been revealed that particularly, compound 2e and 2j (IC50 value 12.5 μM) have shown better cytotoxicity effect against three cell lines. According to results of SAR study, it was found that 3,4-dihydropyrimidines of curcumin, 2c, 2d, 2j and 2n exhibited better antioxidant activity than curcumin. A correlation of structure and activities relationship of these compounds with respect to drug score profiles and other physico-chemical properties of drugs are described and verified experimentally. Therefore, we conclude that physico-chemical analyses may prove structural features of curcumin analogues with their promising combined cytotoxicity/antioxidant activity and it is also concluded from virtual and practical screening that the compounds were varied to possess a broad range of lipophilic character, revealed by Log P values. PMID:27318975

  11. [Enhancing glutamate decarboxylase activity by site-directed mutagenesis: an insight from Ramachandran plot].

    PubMed

    Ke, Piyu; Huang, Jun; Hu, Sheng; Zhao, Weirui; Lü, Changjiang; Yu, Kai; Lei, Yinlin; Wang, Jinbo; Mei, Lehe

    2016-01-01

    Glutamate decarboxylase (GAD) can catalyze the decarboxylation of glutamate into γ-aminobutyrate (GABA) and is the only enzyme of GABA biosynthesis. Improving GAD activity and thermostability will be helpful for the highly efficient biosynthesis of GABA. According to the Ramachandran plot information of GAD 1407 three-dimensional structure from Lactobacillus brevis CGMCC No. 1306, we identified the unstable site K413 as the mutation target, constructed the mutant GAD by site-directed mutagenesis and measured the thermostability and activity of the wide type and mutant GAD. Mutant K413A led to a remarkably slower inactivation rate, and its half-life at 50 °C reached 105 min which was 2.1-fold higher than the wild type GAD1407. Moreover, mutant K413I exhibited 1.6-fold higher activity in comparison with the wide type GAD1407, although it had little improvement in thermostability of GAD. Ramachandran plot can be considered as a potential approach to increase GAD thermostability and activity. PMID:27443004

  12. [Enhancing glutamate decarboxylase activity by site-directed mutagenesis: an insight from Ramachandran plot].

    PubMed

    Ke, Piyu; Huang, Jun; Hu, Sheng; Zhao, Weirui; Lü, Changjiang; Yu, Kai; Lei, Yinlin; Wang, Jinbo; Mei, Lehe

    2016-01-01

    Glutamate decarboxylase (GAD) can catalyze the decarboxylation of glutamate into γ-aminobutyrate (GABA) and is the only enzyme of GABA biosynthesis. Improving GAD activity and thermostability will be helpful for the highly efficient biosynthesis of GABA. According to the Ramachandran plot information of GAD 1407 three-dimensional structure from Lactobacillus brevis CGMCC No. 1306, we identified the unstable site K413 as the mutation target, constructed the mutant GAD by site-directed mutagenesis and measured the thermostability and activity of the wide type and mutant GAD. Mutant K413A led to a remarkably slower inactivation rate, and its half-life at 50 °C reached 105 min which was 2.1-fold higher than the wild type GAD1407. Moreover, mutant K413I exhibited 1.6-fold higher activity in comparison with the wide type GAD1407, although it had little improvement in thermostability of GAD. Ramachandran plot can be considered as a potential approach to increase GAD thermostability and activity.

  13. Synthesis and biological activity of pyrrole analogues of combretastatin A-4.

    PubMed

    Jung, Eun-Kyung; Leung, Euphemia; Barker, David

    2016-07-01

    A series of pyrrole analogues of combretastatin (CA-4) were synthesized and tested for their anti-proliferative activity. The highly diastereoselective acyl-Claisen rearrangement was used to provide 2,3-syn disubstituted morpholine amides which were used as precursors for the various analogues. This synthesis allows for the preparation of 1,2- and 2,3-diaryl-1H-pyrroles which are both geometrically similar to CA-4. These pyrrolic analogues were tested for their anti-proliferative activity against two human cell lines, K562 and MDA-MB-231 with 2,3-diaryl-1H-pyrrole 35 exhibiting the most potent activity with IC50 value of 0.07μM against MDA-MB-231 cell line.

  14. 1,2,3-Triazole-based analogue of benznidazole displays remarkable activity against Trypanosoma cruzi.

    PubMed

    de Andrade, Peterson; Galo, Oswaldo A; Carvalho, Marcelo R; Lopes, Carla D; Carneiro, Zumira A; Sesti-Costa, Renata; de Melo, Eduardo Borges; Silva, João S; Carvalho, Ivone

    2015-11-01

    The current treatment of Chagas disease is based on the use of two drugs, nifurtimox and benznidazole, which present limited efficacy in the chronic stage of the disease and toxic side effects. Although some progress has been made in the development of new drugs to treat this disease, the discovery of novel compounds is urgently required. In this work we report the synthesis and biological evaluation of 1,2,3-triazole-based analogues of benznidazole. A small series of 27 compounds was successfully synthesized via microwave-assisted copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC) from N-benzyl-2-azidoacetamide (1) and a set of commercial terminal alkynes. Analogues 24 (IC50 40 μM) and 28 (IC50 50 μM) showed comparable activities to benznidazole (IC50 34 μM) against trypomastigote form and analogue 15 (IC50 7 μM) was found to be the most active. Regarding the cytotoxicity assessment of the series, most compounds were not cytotoxic. This work shows that the designed strategy is efficiently capable of generating novel benzindazole analogues and reveals one analogue is more active than benznidazole. PMID:26476667

  15. Regulation of Glutamate Dehydrogenase Activity in Relation to Carbon Limitation and Protein Catabolism in Carrot Cell Suspension Cultures 1

    PubMed Central

    Robinson, Sharon A.; Stewart, George R.; Phillips, Richard

    1992-01-01

    Glutamate dehydrogenase (GDH) specific activity and function have been studied in cell suspension cultures of carrot (Daucus carota L. cv Chantenay) in response to carbon and nitrogen supply in the culture medium. The specific activity of GDH was derepressed in sucrose-starved cells concomitant with protein catabolism, ammonium excretion, and the accumulation of metabolically active amino acids. The addition of sucrose led to a rapid decrease in GDH specific activity, an uptake of ammonium from the medium, and a decrease in amino acid levels. The extent of GDH derepression was correlated positively with cellular glutamate concentration. These findings strengthen the view that the function of GDH is the catabolism of glutamate, which under conditions of carbon stress provides carbon skeletons for tricarboxylic acid cycle activity. PMID:16668745

  16. A high-throughput colorimetric assay to measure the activity of glutamate decarboxylase.

    PubMed

    Yu, Kai; Hu, Sheng; Huang, Jun; Mei, Le-He

    2011-08-10

    A pH-sensitive colorimetric assay has been established to quantitatively measure glutamate decarboxylase (GAD) activity in bacterial cell extracts using a microplate format. GAD catalyzes the irreversible α-decarboxylation of L-glutamate to γ-aminobutyrate. The assay is based on the color change of bromocresol green due to an increase in pH as protons are consumed during the enzyme-catalyzed reaction. Bromocresol green was chosen as the indicator because it has a similar pK(a) to the acetate buffer used. The corresponding absorbance change at 620 nm was recorded with a microplate reader as the reaction proceeded. A difference in the enzyme preparation pH and optimal pH for GAD activity of 2.5 did not prevent this method from successfully allowing the determination of reaction kinetic parameters and the detection of improvements in enzymatic activity with a low coefficient of variance. Our assay is simple, rapid, requires minimal sample concentration and can be carried out in robotic high-throughput devices used as standard in directed evolution experiments. In addition, it is also applicable to other reactions that involve a change in pH.

  17. Orally Active Metabotropic Glutamate Subtype 2 Receptor Positive Allosteric Modulators: Structure-Activity Relationships and Assessment in a Rat Model of Nicotine Dependence

    PubMed Central

    Sidique, Shyama; Dhanya, Raveendra-Panickar; Sheffler, Douglas J.; Nickols, Hilary Highfield; Yang, Li; Dahl, Russell; Mangravita-Novo, Arianna; Smith, Layton H.; D’Souza, Manoranjan S.; Semenova, Svetlana; Conn, P. Jeffrey; Markou, Athina; Cosford, Nicholas D. P.

    2012-01-01

    Compounds that modulate metabotropic glutamate subtype 2 (mGlu2) receptors have the potential to treat several disorders of the central nervous system (CNS) including drug dependence. Herein we describe the synthesis and structure-activity relationship (SAR) studies around a series of mGlu2 receptor positive allosteric modulators (PAMs). The effects of N-substitution (R1) and substitutions on the aryl ring (R2) were identified as key areas for SAR exploration (Figure 3). Investigation of the effects of varying substituents in both the isoindolinone (2) and benzisothiazolone (3) series led to compounds with improved in vitro potency and/or efficacy. In addition, several analogues exhibited promising pharmacokinetic (PK) properties. Furthermore, compound 2 was shown to dose-dependently decrease nicotine self-administration in rats following oral administration. Our data, showing for the first time efficacy of an mGlu2 receptor PAM in this in vivo model, suggest potential utility for the treatment of nicotine dependence in humans. PMID:23009245

  18. Anti‐flavivirus Activity of Different Tritylated Pyrimidine and Purine Nucleoside Analogues

    PubMed Central

    Serpi, Michaela; Slusarczyk, Magdalena; Ferrari, Valentina; Pertusati, Fabrizio; Meneghesso, Silvia; Derudas, Marco; Farleigh, Laura; Zanetta, Paola; Bugert, Joachim

    2016-01-01

    Abstract A series of tritylated and dimethoxytritylated analogues of selected pyrimidine and purine nucleosides were synthesized and evaluated for their in vitro inhibitory activity against two important members of the genus Flavivirus in the Flaviviridae family, the yellow fever (YFV) and dengue viruses (DENV). Among all compounds tested, the 5′‐O‐tritylated and the 5′‐O‐dimethoxytritylated 5‐fluorouridine derivatives exerted potency against YFV. Interestingly in the series of purine analogues, the 5′O, N‐bis‐tritylated fludarabine derivative revealed strong inhibitory activity against DENV at μm concentrations, however significantly weaker potency against YFV. PMID:27551659

  19. A new class of conjugated strigolactone analogues with fluorescent properties: synthesis and biological activity.

    PubMed

    Bhattacharya, Chaitali; Bonfante, Paola; Deagostino, Annamaria; Kapulnik, Yoram; Larini, Paolo; Occhiato, Ernesto G; Prandi, Cristina; Venturello, Paolo

    2009-09-01

    A new class of strigolactone analogues has been synthesized. They differ from known molecules, both of natural and synthetic origin, in two main features. The conjugated system extends from the enol ether bridge to the A ring, the B ring is a heterocycle while the C ring is a cyclic ketone instead of a gamma-lactone. The key step of the synthesis is a Nazarov cyclization on activated substrates. Bioassays using Orobanche seeds have revealed that all the molecules strongly stimulate germination; in particular the oxygen containing analogues are the most active. Interestingly, some of the new molecules show fluorescent properties. PMID:19675895

  20. Anti-flavivirus Activity of Different Tritylated Pyrimidine and Purine Nucleoside Analogues.

    PubMed

    McGuigan, Christopher; Serpi, Michaela; Slusarczyk, Magdalena; Ferrari, Valentina; Pertusati, Fabrizio; Meneghesso, Silvia; Derudas, Marco; Farleigh, Laura; Zanetta, Paola; Bugert, Joachim

    2016-06-01

    A series of tritylated and dimethoxytritylated analogues of selected pyrimidine and purine nucleosides were synthesized and evaluated for their in vitro inhibitory activity against two important members of the genus Flavivirus in the Flaviviridae family, the yellow fever (YFV) and dengue viruses (DENV). Among all compounds tested, the 5'-O-tritylated and the 5'-O-dimethoxytritylated 5-fluorouridine derivatives exerted potency against YFV. Interestingly in the series of purine analogues, the 5'O, N-bis-tritylated fludarabine derivative revealed strong inhibitory activity against DENV at μm concentrations, however significantly weaker potency against YFV. PMID:27551659

  1. Mechanistic insights into ferredoxin-NADP(H) reductase catalysis involving the conserved glutamate in the active site.

    PubMed

    Dumit, Verónica I; Essigke, Timm; Cortez, Néstor; Ullmann, G Matthias

    2010-04-01

    Plant-type ferredoxin-NADP(H) reductases (FNRs) are flavoenzymes harboring one molecule of noncovalently bound flavin adenine dinucleotide that catalyze reversible reactions between obligatory one-electron carriers and obligatory two-electron carriers. A glutamate next to the C-terminus is strictly conserved in FNR and has been proposed to function as proton donor/acceptor during catalysis. However, experimental studies of this proposed function led to contradicting conclusions about the role of this glutamate in the catalytic mechanism. In the present work, we study the titration behavior of the glutamate in the active site of FNR using theoretical methods. Protonation probabilities for maize FNR were computed for the reaction intermediates of the catalytic cycle by Poisson-Boltzmann electrostatic calculations and Metropolis Monte Carlo titration. The titration behavior of the highly conserved glutamate was found to vary depending on the bound substrates NADP(H) and ferredoxin and also on the redox states of these substrates and the flavin adenine dinucleotide. Our results support the involvement of the glutamate in the FNR catalytic mechanism not only as a proton donor but also as a key residue for stabilizing and destabilizing reaction intermediates. On the basis of our findings, we propose a model rationalizing the function of the glutamate in the reaction cycle, which allows reinterpretation of previous experimental results.

  2. Onboard Detection of Active Canadian Sulfur Springs: A Europa Analogue

    NASA Technical Reports Server (NTRS)

    Castano, Rebecca; Wagstaff, Kiri; Gleeson, Damhnait; Pappalardo, Robert; Chien, Steve; Tran, Daniel; Scharenbroich, Lucas; Moghaddam, Baback; Tang, Benyang; Bue, Brian; Doggett, Thomas; Mandl, Dan; Frye, Stuart

    2008-01-01

    We discuss a current, ongoing demonstration of insitu onboard detection in which the Earth Observing-1 spacecraft detects surface sulfur deposits that originate from underlying springs by distinguishing the sulfur from the ice-rich glacial background, a good analogue for the Europan surface. In this paper, we describe the process of developing the onboard classifier for detecting the presence of sulfur in a hyperspectral scene, including the use of a training/testing set that is not exhaustively labeled, i.e.not all true positives are marked, and the selection of 12, out of 242, Hyperion instrument wavelength bands to use in the onboard detector. This study aims to demonstrate the potential for future missions to capture short-lived science events, make decisions onboard, identify high priority data for downlink and perform onboard change detection. In the future, such capability could help maximize the science return of downlink bandwidth-limited missions, addressing a significant constraint in all deep-space missions.

  3. Synthesis and Structure–Activity Relationship Study of 5a-Carbasugar Analogues of SL0101

    PubMed Central

    2014-01-01

    The Ser/Thr protein kinase, RSK, is associated with oncogenesis, and therefore, there are ongoing efforts to develop RSK inhibitors that are suitable for use in vivo. SL0101 is a natural product that demonstrates selectivity for RSK inhibition. However, SL0101 has a short biological half-life in vivo. To address this issue we designed a set of eight cyclitol analogues, which should be resistant to acid catalyzed anomeric bond hydrolysis. The analogues were synthesized and evaluated for their ability to selectively inhibit RSK in vitro and in cell-based assays. All the analogues were prepared using a stereodivergent palladium-catalyzed glycosylation/cyclitolization for installing the aglycon. The l-cyclitol analogues were found to inhibit RSK2 in in vitro kinase activity with a similar efficacy to that of SL0101, however, the analogues were not specific for RSK in cell-based assays. In contrast, the d-isomers showed no RSK inhibitory activity in in vitro kinase assay. PMID:25589938

  4. KCa2 channels activation prevents [Ca2+]i deregulation and reduces neuronal death following glutamate toxicity and cerebral ischemia

    PubMed Central

    Dolga, A M; Terpolilli, N; Kepura, F; Nijholt, I M; Knaus, H-G; D'Orsi, B; Prehn, J H M; Eisel, U L M; Plant, T; Plesnila, N; Culmsee, C

    2011-01-01

    Exacerbated activation of glutamate receptor-coupled calcium channels and subsequent increase in intracellular calcium ([Ca2+]i) are established hallmarks of neuronal cell death in acute and chronic neurological diseases. Here we show that pathological [Ca2+]i deregulation occurring after glutamate receptor stimulation is effectively modulated by small conductance calcium-activated potassium (KCa2) channels. We found that neuronal excitotoxicity was associated with a rapid downregulation of KCa2.2 channels within 3 h after the onset of glutamate exposure. Activation of KCa2 channels preserved KCa2 expression and significantly reduced pathological increases in [Ca2+]i providing robust neuroprotection in vitro and in vivo. These data suggest a critical role for KCa2 channels in excitotoxic neuronal cell death and propose their activation as potential therapeutic strategy for the treatment of acute and chronic neurodegenerative disorders. PMID:21509037

  5. Inhibition of mammillary body neurons by direct activation of Group II metabotropic glutamate receptors

    PubMed Central

    Lee, Charles C.

    2016-01-01

    The mammillary body is an important neural component of limbic circuitry implicated in learning and memory. Excitatory and inhibitory inputs, primarily mediated by glutamate and gamma-amino butyric acid (GABA), respectively, converge and integrate in this region, before sending information to the thalamus. One potentially overlooked mechanism for inhibition of mammillary body neurons is through direct activation of Group II metabotropic glutamate receptors (mGluRs). Here, whole-cell patch clamp recordings of in vitro slice preparations containing the mammillary body nuclei of the mouse were employed to record responses to bath application of pharmacological agents to isolate the direct effect of activating Group II mGluRs. Application of the Group II mGluR specific agonist, APDC, resulted in a hyperpolarization of the membrane potential in mammillary body neurons, likely resulting from the opening of a potassium conductance. These data suggest that glutamatergic inputs to the mammillary body may be attenuated via Group II mGluRs and implicates a functional role for these receptors in memory-related circuits and broadly throughout the central nervous system. PMID:27390777

  6. Asymmetry of the active site loop conformation between subunits of glutamate-1-semialdehyde aminomutase in solution.

    PubMed

    Campanini, Barbara; Bettati, Stefano; di Salvo, Martino Luigi; Mozzarelli, Andrea; Contestabile, Roberto

    2013-01-01

    Glutamate-1-semialdehyde aminomutase (GSAM) is a dimeric, pyridoxal 5'-phosphate (PLP)- dependent enzyme catalysing in plants and some bacteria the isomerization of L-glutamate-1-semialdehyde to 5-aminolevulinate, a common precursor of chlorophyll, haem, coenzyme B12, and other tetrapyrrolic compounds. During the catalytic cycle, the coenzyme undergoes conversion from pyridoxamine 5'-phosphate (PMP) to PLP. The entrance of the catalytic site is protected by a loop that is believed to switch from an open to a closed conformation during catalysis. Crystallographic studies indicated that the structure of the mobile loop is related to the form of the cofactor bound to the active site, allowing for asymmetry within the dimer. Since no information on structural and functional asymmetry of the enzyme in solution is available in the literature, we investigated the active site accessibility by determining the cofactor fluorescence quenching of PMP- and PLP-GSAM forms. PLP-GSAM is partially quenched by potassium iodide, suggesting that at least one catalytic site is accessible to the anionic quencher and therefore confirming the asymmetry observed in the crystal structure. Iodide induces release of the cofactor from PMP-GSAM, apparently from only one catalytic site, therefore suggesting an asymmetry also in this form of the enzyme in solution, in contrast with the crystallographic data.

  7. IP receptor-dependent activation of PPAR{gamma} by stable prostacyclin analogues

    SciTech Connect

    Falcetti, Emilia; Flavell, David M.; Staels, Bart; Tinker, Andrew; Haworth, Sheila G.; Clapp, Lucie H. . E-mail: l.clapp@ucl.ac.uk

    2007-09-07

    Stable prostacyclin analogues can signal through cell surface IP receptors or by ligand binding to nuclear peroxisome proliferator-activated receptors (PPARs). So far these agents have been reported to activate PPAR{alpha} and PPAR{delta} but not PPAR{gamma}. Given PPAR{gamma} agonists and prostacyclin analogues both inhibit cell proliferation, we postulated that the IP receptor might elicit PPAR{gamma} activation. Using a dual luciferase reporter gene assay in HEK-293 cells stably expressing the IP receptor or empty vector, we found that prostacyclin analogues only activated PPAR{gamma} in the presence of the IP receptor. Moreover, the novel IP receptor antagonist, RO1138452, but not inhibitors of the cyclic AMP pathway, prevented activation. Likewise, the anti-proliferative effects of treprostinil observed in IP receptor expressing cells, were partially inhibited by the PPAR{gamma} antagonist, GW9662. We conclude that PPAR{gamma} is activated through the IP receptor via a cyclic AMP-independent mechanism and contributes to the anti-growth effects of prostacyclin analogues.

  8. Design, synthesis and evaluation of antimicrobial activity of N-terminal modified Leucocin A analogues.

    PubMed

    Bodapati, Krishna Chaitanya; Soudy, Rania; Etayash, Hashem; Stiles, Michael; Kaur, Kamaljit

    2013-07-01

    Class IIa bacteriocins are potent antimicrobial peptides produced by lactic acid bacteria to destroy competing microorganisms. The N-terminal domain of these peptides consists of a conserved YGNGV sequence and a disulphide bond. The YGNGV motif is essential for activity, whereas, the two cysteines involved in the disulphide bond can be replaced with hydrophobic residues. The C-terminal region has variable sequences, and folds into a conserved amphipathic α-helical structure. To elucidate the structure-activity relationship in the N-terminal domain of these peptides, three analogues (1-3) of a class IIa bacteriocin, Leucocin A (LeuA), were designed and synthesized by replacing the N-terminal β-sheet residues of the native peptide with shorter β-turn motifs. Such replacement abolished the antibacterial activity in the analogues, however, analogue 1 was able to competitively inhibit the activity of native LeuA. Native LeuA (37-mer) was synthesized using native chemical ligation method in high yield. Solution conformation study using circular dichroism spectroscopy and molecular dynamics simulations suggested that the C-terminal region of analogue 1 adopts helical folding as found in LeuA, while the N-terminal region did not fold into β-sheet conformation. These structure-activity studies highlight the role of proper folding and complete sequence in the activity of class IIa bacteriocins.

  9. Modulation of activity of Bacillus subtilis regulatory proteins GltC and TnrA by glutamate dehydrogenase.

    PubMed

    Belitsky, Boris R; Sonenshein, Abraham L

    2004-06-01

    The Bacillus subtilis gltAB operon, encoding glutamate synthase, requires a specific positive regulator, GltC, for its expression and is repressed by the global regulatory protein TnrA. The factor that controls TnrA activity, a complex of glutamine synthetase and a feedback inhibitor, such as glutamine, is known, but the signal for modulation of GltC activity has remained elusive. GltC-dependent gltAB expression was drastically reduced when cells were grown in media containing arginine or ornithine or proline, all of which are inducers and substrates of the Roc catabolic pathway. Analysis of gltAB expression in mutants with various defects in the Roc pathway indicated that rocG-encoded glutamate dehydrogenase was required for such repression, suggesting that the substrates or products of this enzyme are the real effectors of GltC. Given that RocG is an enzyme of glutamate catabolism, the main regulatory role of GltC may be prevention of a futile cycle of glutamate synthesis and degradation in the presence of arginine-related amino acids or proline. In addition, high activity of glutamate dehydrogenase was incompatible with activity of TnrA.

  10. Effects of aluminum on activity of krebs cycle enzymes and glutamate dehydrogenase in rat brain homogenate.

    PubMed

    Zatta, P; Lain, E; Cagnolini, C

    2000-05-01

    Aluminum is a neurotoxic agent for animals and humans that has been implicated as an etiological factor in several neurodegenerative diseases and as a destabilizer of cell membranes. Due to its high reactivity, Al3+ is able to interfere with several biological functions, including enzymatic activities in key metabolic pathways. In this paper we report that, among the enzymes that constitute the Krebs cycle, only two are activated by aluminum: alpha-ketoglutarate dehydrogenase and succinate dehydrogenase. In contrast, aconitase, shows decreased activity in the presence of the metal ion. Al3+ also inhibits glutamate dehydrogenase, an allosteric enzyme that is closely linked to the Krebs cycle. A possible correlation between aluminum, the Krebs cycle and aging processes is discussed.

  11. Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway

    SciTech Connect

    Son, Tae Gen; Kawamoto, Elisa M.; Yu, Qian-Sheng; Greig, Nigel H.; Mattson, Mark P.; Camandola, Simonetta

    2013-04-19

    Highlights: •Naphthazarin activates the Nrf2/ARE pathway. •Naphthazarin induces Nrf2-driven genes in neurons and astrocytes. •Naphthazarin protects neurons against excitotoxicity. -- Abstract: Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin. We found that 5,8-dimethoxy-1,4-naphthoquinone (naphthazarin) is a potent activator of the Nrf2/ARE pathway, up-regulates the expression of Nrf2-driven genes in primary neuronal and glial cultures, and protects neurons against glutamate-induced excitotoxicity.

  12. Neuronal activity mediated regulation of glutamate transporter GLT‐1 surface diffusion in rat astrocytes in dissociated and slice cultures

    PubMed Central

    Al Awabdh, Sana; Gupta‐Agarwal, Swati; Sheehan, David F.; Muir, James; Norkett, Rosalind; Twelvetrees, Alison E.; Griffin, Lewis D.

    2016-01-01

    The astrocytic GLT‐1 (or EAAT2) is the major glutamate transporter for clearing synaptic glutamate. While the diffusion dynamics of neurotransmitter receptors at the neuronal surface are well understood, far less is known regarding the surface trafficking of transporters in subcellular domains of the astrocyte membrane. Here, we have used live‐cell imaging to study the mechanisms regulating GLT‐1 surface diffusion in astrocytes in dissociated and brain slice cultures. Using GFP‐time lapse imaging, we show that GLT‐1 forms stable clusters that are dispersed rapidly and reversibly upon glutamate treatment in a transporter activity‐dependent manner. Fluorescence recovery after photobleaching and single particle tracking using quantum dots revealed that clustered GLT‐1 is more stable than diffuse GLT‐1 and that glutamate increases GLT‐1 surface diffusion in the astrocyte membrane. Interestingly, the two main GLT‐1 isoforms expressed in the brain, GLT‐1a and GLT‐1b, are both found to be stabilized opposed to synapses under basal conditions, with GLT‐1b more so. GLT‐1 surface mobility is increased in proximity to activated synapses and alterations of neuronal activity can bidirectionally modulate the dynamics of both GLT‐1 isoforms. Altogether, these data reveal that astrocytic GLT‐1 surface mobility, via its transport activity, is modulated during neuronal firing, which may be a key process for shaping glutamate clearance and glutamatergic synaptic transmission. GLIA 2016;64:1252–1264 PMID:27189737

  13. Glutamate-activated chloride channels: Unique fipronil targets present in insects but not in mammals

    PubMed Central

    Narahashi, Toshio; Zhao, Xilong; Ikeda, Tomoko; Salgado, Vincent L.; Yeh, Jay Z.

    2009-01-01

    Selectivity to insects over mammals is one of the important characteristics for a chemical to become a useful insecticide. Fipronil was found to block cockroach GABA receptors more potently than rat GABAA receptors. Furthermore, glutamate-activated chloride channels (GluCls), which are present in cockroaches but not in mammals, were very sensitive to the blocking action of fipronil. The IC50s of fipronil block were 30 nM in cockroach GABA receptors and 1600 nM in rat GABAA receptors. Moreover, GluCls of cockroach neurons had low IC50s for fipronil. Two types of glutamate-induced chloride current were obswerved: desensitizing and non-desensitizing, with fipronil IC50s of 800 and 10 nM, respectively. We have developed methods to separately record these two types of GluCls. The non-desensitizing and desensitizing currents were selectively inhibited by trypsin and polyvinylpyrrolidone, respectively. In conclusion, in addition to GABA receptors, GluCls play a crucial role in selectivity of fipronil to insects over mammals. GluCls form the basis for development of selective and safe insecticides. PMID:20563240

  14. Alleviating pain hypersensitivity through activation of type 4 metabotropic glutamate receptor.

    PubMed

    Vilar, Bruno; Busserolles, Jérôme; Ling, Bing; Laffray, Sophie; Ulmann, Lauriane; Malhaire, Fanny; Chapuy, Eric; Aissouni, Youssef; Etienne, Monique; Bourinet, Emmanuel; Acher, Francine; Pin, Jean-Philippe; Eschalier, Alain; Goudet, Cyril

    2013-11-27

    Hyperactivity of the glutamatergic system is involved in the development of central sensitization in the pain neuraxis, associated with allodynia and hyperalgesia observed in patients with chronic pain. Herein we study the ability of type 4 metabotropic glutamate receptors (mGlu4) to regulate spinal glutamate signaling and alleviate chronic pain. We show that mGlu4 are located both on unmyelinated C-fibers and spinal neurons terminals in the inner lamina II of the spinal cord where they inhibit glutamatergic transmission through coupling to Cav2.2 channels. Genetic deletion of mGlu4 in mice alters sensitivity to strong noxious mechanical compression and accelerates the onset of the nociceptive behavior in the inflammatory phase of the formalin test. However, responses to punctate mechanical stimulation and nocifensive responses to thermal noxious stimuli are not modified. Accordingly, pharmacological activation of mGlu4 inhibits mechanical hypersensitivity in animal models of inflammatory or neuropathic pain while leaving acute mechanical perception unchanged in naive animals. Together, these results reveal that mGlu4 is a promising new target for the treatment of chronic pain. PMID:24285900

  15. Synthesis, biological activity and solution structure of new analogues of the antimicrobial Gramicidin S.

    PubMed

    Kamysz, Elżbieta; Mickiewicz, Beata; Kamysz, Wojciech; Bielińska, Sylwia; Rodziewicz-Motowidło, Sylwia; Ciarkowski, Jerzy

    2011-03-01

    Gramicidin S (GS) is a cyclo-decapeptide antibiotic isolated from Bacillus brevis. The structural studies have shown that GS forms a two-stranded antiparallel β-sheet imposed by two II' β-turns. Despite its wide Gram+ and Gram- antimicrobial spectrum, GS is useless in therapy because of its high hemotoxicity in humans. It was found, however, that the analogues of GS-14 (GS with 14 amino acid residues) attained a better antimicrobial selectivity when their amphipatic moments were perturbed. In this study, we report effects of similar perturbations imposed on GS cyclo-decapeptide analogues. Having solved their structures by NMR/molecular dynamics and having tested their activities/selectivities, we have concluded that the idea of perturbation of the amphipatic moment does not work for GS-10_0 analogues. An innovative approach to the synthesis of head-to-tail cyclopeptides was used.

  16. Activation of metabotropic glutamate receptors regulates ribosomes of cochlear nucleus neurons.

    PubMed

    Carzoli, Kathryn L; Hyson, Richard L

    2014-01-01

    The brain stem auditory system of the chick is an advantageous model for examining changes that occur as a result of deafness. Elimination of acoustic input through cochlear ablation results in the eventual death of approximately 30% of neurons in the chick cochlear nucleus, nucleus magnocellularis (NM). One early change following deafness is an alteration in NM ribosomes, evidenced both by a decrease in protein synthesis and reduction in antigenicity for Y10B, a monoclonal antibody that recognizes a ribosomal epitope. Previous studies have shown that mGluR activation is necessary to maintain Y10B antigenicity and NM viability. What is still unclear, however, is whether or not mGluR activation is sufficient to prevent deafness-induced changes in these neurons, or if other activity-dependent factors are also necessary. The current study investigated the ability of mGluR activation to regulate cochlear nucleus ribosomes in the absence of auditory nerve input. In vitro methods were employed to periodically pressure eject glutamate or mGluR agonists over neurons on one side of a slice preparation leaving the opposite side of the same slice untreated. Immunohistochemistry was then performed using Y10B in order to assess ribosomal changes. Application of glutamate and both group I and II selective mGluR agonists effectively rescued ribosomal antigenicity on the treated side of the slice in comparison to ribosomes on the untreated side. These findings suggest that administration of mGluR agonists is sufficient to reduce the early interruption of normal ribosomal integrity that is typically seen following loss of auditory nerve activity.

  17. Synthesis of a tricyclic mescaline analogue by catalytic C-H bond activation.

    PubMed

    Ahrendt, Kateri A; Bergman, Robert G; Ellman, Jonathan A

    2003-04-17

    [reaction: see text] A tetrahydrobis(benzofuran) mescaline analogue has been prepared in six steps and 38% overall yield from (4'-O-methyl)methyl gallate. The key step in this synthesis is a tandem cyclization reaction via directed C[bond]H activation followed by olefin insertion.

  18. Molecular design, synthesis and anticoagulant activity evaluation of fluorinated dabigatran analogues.

    PubMed

    Wang, Fei; Ren, Yu-Jie; Dong, Ming-Hui

    2016-06-15

    In the present study, a series of unreported fluorinated dabigatran analogues, which were based on the structural scaffold of dabigatran, were designed by computer-aided simulation. Fifteen fluorinated dabigatran analogues were screened and synthesized. All target compounds were characterized by (1)H NMR, (13)C NMR, (19)F NMR and HRMS. According to the preliminary screening results of inhibition ratio, eleven analogues (inhibition ratio >90%) were evaluated for antithrombin activity in vitro (IC50). The test results expressed that all the analogues showed effective inhibitory activities against thrombin. Especially, compounds 8f, 8k and 8o, with IC50 values of 1.81, 3.21 and 2.16nM, respectively, showed remarkable anticoagulant activities which were in the range of reference drug dabigatran (IC50=1.23nM). Moreover, compounds 8k and 8o were developed to investigate their anticoagulant activities in vivo. In those part, compound 8o exhibited a fairly strong inhibitory action for arteriovenous thrombosis with inhibition ratio of 84.66%, which was comparable with that of dabigatran (85.07%). Docking simulations demonstrated that these compounds could act as candidates for further development of novel anticoagulant drugs. PMID:27166573

  19. Molecular design, synthesis and anticoagulant activity evaluation of fluorinated dabigatran analogues.

    PubMed

    Wang, Fei; Ren, Yu-Jie; Dong, Ming-Hui

    2016-06-15

    In the present study, a series of unreported fluorinated dabigatran analogues, which were based on the structural scaffold of dabigatran, were designed by computer-aided simulation. Fifteen fluorinated dabigatran analogues were screened and synthesized. All target compounds were characterized by (1)H NMR, (13)C NMR, (19)F NMR and HRMS. According to the preliminary screening results of inhibition ratio, eleven analogues (inhibition ratio >90%) were evaluated for antithrombin activity in vitro (IC50). The test results expressed that all the analogues showed effective inhibitory activities against thrombin. Especially, compounds 8f, 8k and 8o, with IC50 values of 1.81, 3.21 and 2.16nM, respectively, showed remarkable anticoagulant activities which were in the range of reference drug dabigatran (IC50=1.23nM). Moreover, compounds 8k and 8o were developed to investigate their anticoagulant activities in vivo. In those part, compound 8o exhibited a fairly strong inhibitory action for arteriovenous thrombosis with inhibition ratio of 84.66%, which was comparable with that of dabigatran (85.07%). Docking simulations demonstrated that these compounds could act as candidates for further development of novel anticoagulant drugs.

  20. TRPA1 activation by lidocaine in nerve terminals results in glutamate release increase

    SciTech Connect

    Piao, L.-H.; Fujita, Tsugumi; Jiang, C.-Y.; Liu Tao; Yue, H.-Y.; Nakatsuka, Terumasa; Kumamoto, Eiichi

    2009-02-20

    We examined the effects of local anesthetics lidocaine and procaine on glutamatergic spontaneous excitatory transmission in substantia gelatinosa (SG) neurons in adult rat spinal cord slices with whole-cell patch-clamp techniques. Bath-applied lidocaine (1-5 mM) dose-dependently and reversibly increased the frequency but not the amplitude of spontaneous excitatory postsynaptic current (sEPSC) in SG neurons. Lidocaine activity was unaffected by the Na{sup +}-channel blocker, tetrodotoxin, and the TRPV1 antagonist, capsazepine, but was inhibited by the TRP antagonist, ruthenium red. In the same neuron, the TRPA1 agonist, allyl isothiocyanate, and lidocaine both increased sEPSC frequency. In contrast, procaine did not produce presynaptic enhancement. These results indicate that lidocaine activates TRPA1 in nerve terminals presynaptic to SG neurons to increase the spontaneous release of L-glutamate.

  1. Pituitary Adenylate cyclase-activating polypeptide orchestrates neuronal regulation of the astrocytic glutamate-releasing mechanism system xc (.).

    PubMed

    Kong, Linghai; Albano, Rebecca; Madayag, Aric; Raddatz, Nicholas; Mantsch, John R; Choi, SuJean; Lobner, Doug; Baker, David A

    2016-05-01

    Glutamate signaling is achieved by an elaborate network involving neurons and astrocytes. Hence, it is critical to better understand how neurons and astrocytes interact to coordinate the cellular regulation of glutamate signaling. In these studies, we used rat cortical cell cultures to examine whether neurons or releasable neuronal factors were capable of regulating system xc (-) (Sxc), a glutamate-releasing mechanism that is expressed primarily by astrocytes and has been shown to regulate synaptic transmission. We found that astrocytes cultured with neurons or exposed to neuronal-conditioned media displayed significantly higher levels of Sxc activity. Next, we demonstrated that the pituitary adenylate cyclase-activating polypeptide (PACAP) may be a neuronal factor capable of regulating astrocytes. In support, we found that PACAP expression was restricted to neurons, and that PACAP receptors were expressed in astrocytes. Interestingly, blockade of PACAP receptors in cultures comprised of astrocytes and neurons significantly decreased Sxc activity to the level observed in purified astrocytes, whereas application of PACAP to purified astrocytes increased Sxc activity to the level observed in cultures comprised of neurons and astrocytes. Collectively, these data reveal that neurons coordinate the actions of glutamate-related mechanisms expressed by astrocytes, such as Sxc, a process that likely involves PACAP. A critical gap in modeling excitatory signaling is how distinct components of the glutamate system expressed by neurons and astrocytes are coordinated. In these studies, we found that system xc (-) (Sxc), a glutamate release mechanism expressed by astrocytes, is regulated by releasable neuronal factors including PACAP. This represents a novel form of neuron-astrocyte communication, and highlights the possibility that pathological changes involving astrocytic Sxc may stem from altered neuronal activity.

  2. Overexpression of α-synuclein simultaneously increases glutamate NMDA receptor phosphorylation and reduces glucocerebrosidase activity.

    PubMed

    Yang, Junfeng; Hertz, Ellen; Zhang, Xiaoqun; Leinartaité, Lina; Lundius, Ebba Gregorsson; Li, Jie; Svenningsson, Per

    2016-01-12

    Progressive accumulation of α-synuclein (α-syn)-containing protein aggregates throughout the nervous system is a pathological hallmark of Parkinson's disease (PD). The mechanisms whereby α-syn exerts neurodegeneration remain to be fully understood. Here we show that overexpression of α-syn in transgenic mice leads to increased phosphorylation of glutamate NMDA receptor (NMDAR) subunits NR1 and NR2B in substantia nigra and striatum as well as reduced glucocerebrosidase (GCase) levels. Similarly, molecular studies performed in mouse N2A cells stably overexpressing human α-syn ((α-syn)N2A) showed that phosphorylation states of the same NMDAR subunits were increased, whereas GCase levels and lysosomal GCase activity were reduced. (α-syn)N2A cells showed an increased sensitivity to neurotoxicity towards 6-hydroxydopamine and NMDA. However, wildtype N2A, but not (α-syn)N2A cells, showed a further reduction in viability when co-incubated with 6-hydroxydopamine and the lysosomal inhibitors NH4Cl and leupeptin, suggesting that α-syn per se perturbs lysosomal functions. NMDA treatment reduced lysosomal GCase activity to the same extent in (α-syn)N2A cells as in wildtype N2A cells, indicating that the α-syn-dependent difference in NMDA neurotoxicity is unrelated to an altered GCase activity. Nevertheless, these data provide molecular evidence that overexpression of α-syn simultaneously induces two potential neurotoxic hits by increasing glutamate NMDA receptor phosphorylation, consistent with increased NMDA receptors functionality, and reducing GCase activity. PMID:26610904

  3. Antimycobacterial activity generated by the amide coupling of (-)-fenchone derived aminoalcohol with cinnamic acids and analogues.

    PubMed

    Slavchev, Ivaylo; Dobrikov, Georgi M; Valcheva, Violeta; Ugrinova, Iva; Pasheva, Evdokia; Dimitrov, Vladimir

    2014-11-01

    Aminoethyl substituted 2-endo-fenchol prepared from (-)-fenchone was used as scaffold for the synthesis of series of 31 amide structures by N-acylation applying cinnamic acids and analogues. The evaluation of their in vitro activity against Mycobacterium tuberculosis H37Rv showed for some of them promising activity-up to 0.2 μg/ml, combined with relatively low cytotoxicity of the selected active compounds.

  4. Characterization of the intrinsic activity for a novel class of cannabinoid receptor ligands: Indole Quinuclidine analogues

    PubMed Central

    Franks, Lirit N.; Ford, Benjamin M.; Madadi, Nikhil R.; Penthala, Narsimha R.; Crooks, Peter A.; Prather, Paul L.

    2014-01-01

    Our laboratory recently reported that a group of novel indole quinuclidine analogues bind with nanomolar affinity to cannabinoid type-1 and type-2 receptors. This study characterized the intrinsic activity of these compounds by determining whether they exhibit agonist, antagonist, or inverse agonist activity at cannabinoid type-1 and/or type-2 receptors. Cannabinoid receptors activate Gi/Go-proteins that then proceed to inhibit activity of the downstream intracellular effector adenylyl cyclase. Therefore, intrinsic activity was quantified by measuring the ability of compounds to modulate levels of intracellular cAMP in intact cells. Concerning cannabinoid type-1 receptors endogenously expressed in Neuro2A cells, a single analogue exhibited agonist activity, while eight acted as neutral antagonists and two possessed inverse agonist activity. For cannabinoid type-2 receptors stably expressed in CHO cells, all but two analogues acted as agonists; these two exceptions exhibited inverse agonist activity. Confirming specificity at cannabinoid type-1 receptors, modulation of adenylyl cyclase activity by all proposed agonists and inverse agonists was blocked by co-incubation with the neutral cannabinoid type-1 antagonist O-2050. All proposed cannabinoid type-1 receptor antagonists attenuated adenylyl cyclase modulation by cannabinoid agonist CP-55,940. Specificity at cannabinoid type-2 receptors was confirmed by failure of all compounds to modulate adenylyl cyclase activity in CHO cells devoid of cannabinoid type-2 receptors. Further characterization of select analogues demonstrated concentration-dependent modulation of adenylyl cyclase activity with potencies similar to their respective affinities for cannabinoid receptors. Therefore, indole quinuclidines are a novel structural class of compounds exhibiting high affinity and a range of intrinsic activity at cannabinoid type-1 and type-2 receptors. PMID:24858620

  5. Methyl substitution of 2-aminobicyclo[3.1.0]hexane 2,6-dicarboxylate (LY354740) determines functional activity at metabotropic glutamate receptors: identification of a subtype selective mGlu2 receptor agonist.

    PubMed

    Dominguez, Carmen; Prieto, Lourdes; Valli, Matthew J; Massey, Steven M; Bures, Mark; Wright, Rebecca A; Johnson, Bryan G; Andis, Sherri L; Kingston, Ann; Schoepp, Darryle D; Monn, James A

    2005-05-19

    LY354740 (1) is a highly potent and selective agonist of metabotropic glutamate (mGlu) receptors 2 and 3. In the present study, we have prepared C3- and C4-methyl-substituted variants of rac-1, compounds 5, 9, and 13. Each of these racemic methyl-substituted analogues displaced specific binding of the mGlu2/3 receptor antagonist (3)H-2S-2-amino-2-(1S,2S-2-carboxycycloprop-1-yl)-3-(xanth-9-yl)propanoic acid ((3)H-LY341495) from membranes expressing mGlu2 or mGlu3 receptor subtypes. Evaluation of the functional effects of this series on second messenger responses in cells expressing human mGlu2 or mGlu3 receptors revealed C3beta-methyl analogue 5 to possess antagonist properties at both mGlu2 and mGlu3 receptors while C4beta-methyl analogue 9 acts as a full agonist at each of these targets. Unexpectedly, we found that incorporation of a methyl substituent at the C4alpha-position as in analogue 13 results in a mixed mGlu2 agonist/mGlu3 antagonist pharmacological profile. All of the mGlu2 agonist and mGlu3 antagonist activity of rac-13 was found to reside in its resolved (+)-isomer. PMID:15887967

  6. In vitro antifungal and antibiofilm activities of halogenated quinoline analogues against Candida albicans and Cryptococcus neoformans.

    PubMed

    Zuo, Ran; Garrison, Aaron T; Basak, Akash; Zhang, Peilan; Huigens, Robert W; Ding, Yousong

    2016-08-01

    With the increasing prevalence of fungal infections coupled with emerging drug resistance, there is an urgent need for new and effective antifungal agents. Here we report the antifungal activities of 19 diverse halogenated quinoline (HQ) small molecules against Candida albicans and Cryptococcus neoformans. Four HQ analogues inhibited C. albicans growth with a minimum inhibitory concentration (MIC) of 100 nM, whilst 16 analogues effectively inhibited C. neoformans at MICs of 50-780 nM. Remarkably, two HQ analogues eradicated mature C. albicans and C. neoformans biofilms [minimum biofilm eradication concentration (MBEC) = 6.25-62.5 µM]. Several active HQs were found to penetrate into fungal cells, whilst one inactive analogue was unable to, suggesting that HQs elicit their antifungal activities through an intracellular mode of action. HQs are a promising class of small molecules that may be useful in future antifungal treatments. PMID:27256584

  7. [Synthesis, conformation, and spectroscopy of nucleoside analogues concerning their antiviral activity].

    PubMed

    Kuśmierek, Jarosław T; Stolarski, Ryszard

    2015-01-01

    Chemically modified analogues of nucleosides and nucleotides, have been thoroughly investigated since the discovery of DNA double helix by Watson and Crick in 1953 (Nature 171: 737). Chemical structures, first of all tautomerism, of the nucleic acid bases, as well as the conformations of the nucleic acids constituents, determine the secondary and tertiary structures of DNA and RNA polymers. Similarly, structural and dynamic parameters of nucleoside derivatives determine their biological activity in mutagenesis, neoplastic transformation, as well as antiviral or anticancer properties. In this review, a multidisciplinary approach of Prof. David Shugar's group is presented in the studies on nucleosides and nucleotides. It consists in chemical syntheses of suitable analogues, measurements of physicochemical and spectral parameters, conformational analysis by means of nuclear magnetic resonance (NMR) and X-ray diffraction, as well as characteristics of the nucleoside analogues as inhibitors of some selected, target enzymes, crucial in respect to antiviral activity of the analogues. These long-lasting studies follows upon the line of the main paradigm of molecular biophysics, i. e. structure-activity relationship. PMID:26677575

  8. Experimentally induced diabetes causes glial activation, glutamate toxicity and cellular damage leading to changes in motor function

    PubMed Central

    Nagayach, Aarti; Patro, Nisha; Patro, Ishan

    2014-01-01

    Behavioral impairments are the most empirical consequence of diabetes mellitus documented in both humans and animal models, but the underlying causes are still poorly understood. As the cerebellum plays a major role in coordination and execution of the motor functions, we investigated the possible involvement of glial activation, cellular degeneration and glutamate transportation in the cerebellum of rats, rendered diabetic by a single injection of streptozotocin (STZ; 45 mg/kg body weight; intraperitoneally). Motor function alterations were studied using Rotarod test (motor coordination) and grip strength (muscle activity) at 2nd, 4th, 6th, 8th, 10th, and 12th week post-diabetic confirmation. Scenario of glial (astroglia and microglia) activation, cell death and glutamate transportation was gaged using immunohistochemistry, histological study and image analysis. Cellular degeneration was clearly demarcated in the diabetic cerebellum. Glial cells were showing sequential and marked activation following diabetes in terms of both morphology and cell number. Bergmann glial cells were hypertrophied and distorted. Active caspase-3 positive apoptotic cells were profoundly present in all three cerebellar layers. Reduced co-labeling of GLT-1 and GFAP revealed the altered glutamate transportation in cerebellum following diabetes. These results, exclusively derived from histology, immunohistochemistry and cellular quantification, provide first insight over the associative reciprocity between the glial activation, cellular degeneration and reduced glutamate transportation, which presumably lead to the behavioral alterations following STZ-induced diabetes. PMID:25400546

  9. New Atglistatin closely related analogues: Synthesis and structure-activity relationship towards adipose triglyceride lipase inhibition.

    PubMed

    Roy, Pierre-Philippe; D'Souza, Kenneth; Cuperlovic-Culf, Miroslava; Kienesberger, Petra C; Touaibia, Mohamed

    2016-08-01

    Adipose Triglyceride Lipase (ATGL) performs the first and rate-limiting step in lipolysis by hydrolyzing triacylglycerols stored in lipid droplets to diacylglycerols. By mediating lipolysis in adipose and non-adipose tissues, ATGL is a major regulator of overall energy metabolism and plasma lipid levels. Since chronically high levels of plasma lipids are linked to metabolic disorders including insulin resistance and type 2 diabetes, ATGL is an interesting therapeutic target. In the present study, fourteen closely related analogues of Atglistatin (1), a newly discovered ATGL inhibitor, were synthesized, and their ATGL inhibitory activity was evaluated. The effect of these analogues on lipolysis in 3T3-L1 adipocytes clearly shows that inhibition of the enzyme by Atglistatin (1) is due to the presence of the carbamate and N,N-dimethyl moieties on the biaryl central core at meta and para position, respectively. Mono carbamate-substituted analogue C2, in which the carbamate group was in the meta position as in Atglistatin (1), showed slight inhibition. Low dipole moment of Atglistatin (1) compared to the synthesized analogues possibly explains the lower inhibitory activities.

  10. Anti-inflammatory and antimicrobial activities of novel pyrazole analogues.

    PubMed

    Surendra Kumar, R; Arif, Ibrahim A; Ahamed, Anis; Idhayadhulla, Akbar

    2016-09-01

    A new sequence of pyrazole derivatives (1-6) was synthesized from condensation technique under utilizing ultrasound irradiation. Synthesized compounds were characterized from IR, (1)H NMR, (13)C NMR, Mass and elemental analysis. Synthesized compounds (1-6) were screened for antimicrobial activity. Among the compounds 3 (MIC: 0.25 μg/mL) was exceedingly antibacterially active against gram negative bacteria of Escherichia coli and compound 4 (MIC: 0.25 μg/mL) was highly active against gram positive bacteria of Streptococcus epidermidis compared with standard Ciprofloxacin. Compound 2 (MIC: 1 μg/mL) was highly antifungal active against Aspergillus niger proportionate to Clotrimazole. Synthesized compounds (1-6) were screened for anti-inflammatory activity and the compound 2-((5-hydroxy-3-methyl-1H-pyrazol-4-yl)(4-nitrophenyl)methyl)hydrazinecarboxamide (4) was better activity against anti-inflammatory when compared with standard drugs (Diclofenac sodium). Compounds (2, 3 and 4) are the most important molecules and hence the need to develop new drugs of antibacterial, antifungal and anti-inflammatory agents. PMID:27579011

  11. Induction of an Olfactory Memory by the Activation of a Metabotropic Glutamate Receptor

    NASA Astrophysics Data System (ADS)

    Kaba, Hideto; Hayashi, Yasunori; Higuchi, Takashi; Nakanishi, Shigetada

    1994-07-01

    Female mice form an olfactory memory of male pheromones at mating; exposure to the pheromones of a strange male after that mating will block pregnancy. The formation of this memory is mediated by the accessory olfactory system, in which an increase in norepinephrine after mating reduces inhibitory transmission of γ-aminobutyric acid from the granule cells to the mitral cells. This study shows that the activation of mGluR2, a metabotropic glutamate receptor that suppresses the γ-aminobutyric acid inhibition of the mitral cells, permits the formation of a specific olfactory memory without the occurrence of mating by infusion of mGluR2 agonists into the female's accessory olfactory bulb. This memory faithfully reflects the memory formed at mating.

  12. Endogenous activation of metabotropic glutamate receptors supports the proliferation and survival of neural progenitor cells.

    PubMed

    Di Giorgi-Gerevini, V; Melchiorri, D; Battaglia, G; Ricci-Vitiani, L; Ciceroni, C; Busceti, C L; Biagioni, F; Iacovelli, L; Canudas, A M; Parati, E; De Maria, R; Nicoletti, F

    2005-08-01

    The use of neural progenitor cells (NPCs) is limited by the incomplete knowledge of the extracellular signals regulating their proliferation and survival. We report that cultured mouse NPCs express functional mGlu3 and mGlu5 metabotropic glutamate receptors. Pharmacological blockade of both receptors reduced NPC proliferation and survival, whereas activation of mGlu5 receptors substantially enhanced cell proliferation. Adult mice lacking mGlu5 receptors or treated with mGlu5 or mGlu3 receptor antagonists showed a dramatic reduction in the number of dividing neuroprogenitors present in the subventricular zone and in the dentate gyrus of the hippocampus. These data disclose a novel function of mGlu receptors and offer new potential strategies for the optimization of cell replacement therapy in neurodegenerative disorders. PMID:15947794

  13. Structural Insights Lead to a Negamycin Analogue with Improved Antimicrobial Activity against Gram-Negative Pathogens

    PubMed Central

    2015-01-01

    Negamycin is a natural product with antibacterial activity against a broad range of Gram-negative pathogens. Recent revelation of its ribosomal binding site and mode of inhibition has reinvigorated efforts to identify improved analogues with clinical potential. Translation-inhibitory potency and antimicrobial activity upon modification of different moieties of negamycin were in line with its observed ribosomal binding conformation, reaffirming stringent structural requirements for activity. However, substitutions on the N6 amine were tolerated and led to N6-(3-aminopropyl)-negamycin (31f), an analogue showing 4-fold improvement in antibacterial activity against key bacterial pathogens. This represents the most potent negamycin derivative to date and may be a stepping stone toward clinical development of this novel antibacterial class. PMID:26288696

  14. Structure activity relationship study of Mezzettiasides natural products and their four new disaccharide analogues for anticancer/antibacterial activity

    PubMed Central

    Bajaj, Sumit O.; Shi, Pei

    2014-01-01

    Ten members of the mezzettiaside family of natural products were synthesized and evaluated for anticancer and antibacterial activity. Complete anticancer (H460) and antibacterial (B. subtilis) activities for the ten natural products and four new analogues were found. Comparison to the cleistrioside and cleistetroside classes of natural products were made. PMID:25729554

  15. Single channel currents of different amplitude activated by glutamate in a tonic (slow) crayfish muscle.

    PubMed

    Finger, W; Pareto, A

    1987-09-11

    Single channel currents were recorded by means of the patch-clamp technique from a tonic (slow) crayfish muscle in the presence of 5 mM glutamate. The experiments were carried out with 'Gigaohm-seals' in the 'cell-attached' mode at 15-17 degrees C. Five classes of single channel currents with different mean amplitudes were resolved: i1 = -0.75 +/- 0.43 (S.D.) pA, i2 = -1.4 +/- 0.4 pA, i3 = -3.5 +/- 0.63 pA, i4 = -8.5 +/- 0.92 pA and i5 approximately equal to 2 X i4, i2, i3 and i4 were recorded at resting membrane potential, Eo approximately equal to -80 mV (pipette potential Vp = 0), while i1 and i5 were recorded at 40 mV hyperpolarized to Eo (Vp = +40 mV). The current most frequently seen was i4 which is the excitatory glutamate-activated single channel current recorded previously by Franke et al. The membrane reversal potentials and channel conductances for i2 and i4 were estimated to be +60 mV (Eo + 140 mV), 13 pS for i2 and +40 mV (Eo + 120 mV), 80 pS for i4. It was assumed that up to 40 i1 currents could superpose in a single patch to generate a DC current of up to -30 pA with current fluctuations the intensity of which increased with the DC current amplitude. Often variable combinations of i1 to i4 currents could be recorded simultaneously in a single patch. In particular, simultaneous activity of i1, i4; i2, i4 and i3, i4 currents was observed in different single patches.

  16. Biological activity of trisporoids and trisporoid analogues in Mucor mucedo (-).

    PubMed

    Schachtschabel, Doreen; Schimek, Christine; Wöstemeyer, Johannes; Boland, Wilhelm

    2005-06-01

    In the course of their sexual interactions, zygomycete fungi communicate via an elaborate series of carotene-derived compounds, namely trisporic acid and its biosynthetic progenitors. A novel building-block strategy allowed the systematic generation of structurally modified trisporoids along with putative early biosynthetic precursors for physiological tests. The impact of discrete structural elements was documented by the ability of individual compounds to induce sexually committed hyphae in Mucor mucedo. The activity screening contributed to establish general structure-function relationships for trisporoid action. Most crucial for activity were the dimension of the longer side chain, the polarity of functional groups at C(4) and C(13), and the number of conjugated double bonds in the side chain. The presence of an oxygen substituent at the cyclohexene ring is not essential for function. The overall biological activity apparently results from the combination of the various structural elements.

  17. Thinking outside the cleft to understand synaptic activity: contribution of the cystine-glutamate antiporter (System xc-) to normal and pathological glutamatergic signaling.

    PubMed

    Bridges, Richard; Lutgen, Victoria; Lobner, Doug; Baker, David A

    2012-07-01

    System x(c)(-) represents an intriguing target in attempts to understand the pathological states of the central nervous system. Also called a cystine-glutamate antiporter, system x(c)(-) typically functions by exchanging one molecule of extracellular cystine for one molecule of intracellular glutamate. Nonvesicular glutamate released during cystine-glutamate exchange activates extrasynaptic glutamate receptors in a manner that shapes synaptic activity and plasticity. These findings contribute to the intriguing possibility that extracellular glutamate is regulated by a complex network of release and reuptake mechanisms, many of which are unique to glutamate and rarely depicted in models of excitatory signaling. Because system x(c)(-) is often expressed on non-neuronal cells, the study of cystine-glutamate exchange may advance the emerging viewpoint that glia are active contributors to information processing in the brain. It is noteworthy that system x(c)(-) is at the interface between excitatory signaling and oxidative stress, because the uptake of cystine that results from cystine-glutamate exchange is critical in maintaining the levels of glutathione, a critical antioxidant. As a result of these dual functions, system x(c)(-) has been implicated in a wide array of central nervous system diseases ranging from addiction to neurodegenerative disorders to schizophrenia. In the current review, we briefly discuss the major cellular components that regulate glutamate homeostasis, including glutamate release by system x(c)(-). This is followed by an in-depth discussion of system x(c)(-) as it relates to glutamate release, cystine transport, and glutathione synthesis. Finally, the role of system x(c)(-) is surveyed across a number of psychiatric and neurodegenerative disorders.

  18. Activation of Group II Metabotropic Glutamate Receptors Induces Depotentiation in Amygdala Slices and Reduces Fear-Potentiated Startle in Rats

    ERIC Educational Resources Information Center

    Lin, Chia-Ho; Lee, Chia-Ching; Huang, Ya-Chun; Wang, Su-Jane; Gean, Po-Wu

    2005-01-01

    There is a close correlation between long-term potentiation (LTP) in the synapses of lateral amygdala (LA) and fear conditioning in animals. We predict that reversal of LTP (depotentiation) in this area of the brain may ameliorate conditioned fear. Activation of group II metabotropic glutamate receptors (mGluR II) with DCG-IV induces…

  19. Augmented cystine-glutamate exchange by pituitary adenylate cyclase-activating polypeptide signaling via the VPAC1 receptor.

    PubMed

    Resch, Jon M; Albano, Rebecca; Liu, XiaoQian; Hjelmhaug, Julie; Lobner, Doug; Baker, David A; Choi, SuJean

    2014-07-28

    In the central nervous system, cystine import in exchange for glutamate through system xc(-) is critical for the production of the antioxidant glutathione by astrocytes, as well as the maintenance of extracellular glutamate. Therefore, regulation of system xc(-) activity affects multiple aspects of cellular physiology and may contribute to disease states. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuronally-derived peptide that has already been demonstrated to modulate multiple aspects of glutamate signaling suggesting PACAP may also target activity of cystine-glutamate exchange via system xc(-) . In the current study, 24-hour treatment of primary cortical cultures containing neurons and glia with PACAP concentration-dependently increased system xc(-) function as measured by radiolabeled cystine uptake. Furthermore, the increase in cystine uptake was completely abolished by the system xc(-) inhibitor, (S)-4-carboxyphenylglycine (CPG), attributing increases in cystine uptake specifically to system xc(-) activity. Time course and quantitative PCR results indicate that PACAP signaling may increase cystine-glutamate exchange by increasing expression of xCT, the catalytic subunit of system xc(-) . Furthermore, the potentiation of system xc(-) activity by PACAP occurs via a PKA-dependent pathway that is not mediated by the PAC1R, but rather the shared vasoactive intestinal polypeptide receptor VPAC1R. Finally, assessment of neuronal, astrocytic, and microglial-enriched cultures demonstrated that only astrocyte-enriched cultures exhibit enhanced cystine uptake following both PACAP and VIP treatment. These data introduce a novel mechanism by which both PACAP and VIP regulate system xc(-) activity. Synapse, 2014. © 2014 Wiley Periodicals, Inc.

  20. Activity of the lactate-alanine shuttle is independent of glutamate-glutamine cycle activity in cerebellar neuronal-astrocytic cultures.

    PubMed

    Bak, Lasse K; Sickmann, Helle M; Schousboe, Arne; Waagepetersen, Helle S

    The glutamate-glutamine cycle describes the neuronal release of glutamate into the synaptic cleft, astrocytic uptake, and conversion into glutamine, followed by release for use as a neuronal glutamate precursor. This only explains the fate of the carbon atoms, however, and not that of the ammonia. Recently, a role for alanine has been proposed in transfer of ammonia between glutamatergic neurons and astrocytes, denoted the lactate-alanine shuttle (Waagepetersen et al. [ 2000] J. Neurochem. 75:471-479). The role of alanine in this context has been studied further using cerebellar neuronal cultures and corresponding neuronal-astrocytic cocultures. A superfusion paradigm was used to induce repetitively vesicular glutamate release by N-methyl-D-aspartate (NMDA) in the neurons, allowing the relative activity dependency of the lactate-alanine shuttle to be assessed. [(15)N]Alanine (0.2 mM), [2-(15)N]/[5-(15)N]glutamine (0.25 mM), and [(15)N]ammonia (0.3 mM) were used as precursors and cell extracts were analyzed by mass spectrometry. Labeling from [(15)N]alanine in glutamine, aspartate, and glutamate in cerebellar cocultures was independent of depolarization of the neurons. Employing glutamine with the amino group labeled ([2-(15)N]glutamine) as the precursor, an activity-dependent increase in the labeling of both glutamate and aspartate (but not alanine) was observed in the cerebellar neurons. When the amide group of glutamine was labeled ([5-(15)N]glutamine), no labeling could be detected in the analyzed metabolites. Altogether, the results of this study support the existence of the lactate-alanine shuttle and the associated glutamate-glutamine cycle. No direct coupling of the two shuttles was observed, however, and only the glutamate-glutamine cycle seemed activity dependent.

  1. Membrane-Targeting DCAP Analogues with Broad-Spectrum Antibiotic Activity against Pathogenic Bacteria.

    PubMed

    Hurley, Katherine A; Heinrich, Victoria A; Hershfield, Jeremy R; Demons, Samandra T; Weibel, Douglas B

    2015-04-01

    We performed a structure-activity relationship study of 2-((3-(3,6-dichloro-9H-carbazol-9-yl)-2-hydroxypropyl)amino)-2-(hydroxymethyl)propane-1,3-diol (DCAP), which is an antibacterial agent that disrupts the membrane potential and permeability of bacteria. The stereochemistry of DCAP had no effect on the biological activity of DCAP. The aromaticity and electronegativity of the chlorine-substituted carbazole was required for activity, suggesting that its planar and dipolar characteristics orient DCAP in membranes. Increasing the hydrophobicity of the tail region of DCAP enhanced its antibiotic activity. Two DCAP analogues displayed promising antibacterial activity against the BSL-3 pathogens Bacillus anthracis and Francisella tularensis. Codosing DCAP analogues with ampicillin or kanamycin increased their potency. These studies demonstrate that DCAP and its analogues may be a promising scaffold for developing chemotherapeutic agents that bind to bacterial membranes and kill strains of slow-growing or dormant bacteria that cause persistent infections. PMID:25941556

  2. Production of the Ramoplanin Activity Analogue by Double Gene Inactivation

    PubMed Central

    Han, Jungang; Chen, Junsheng; Shao, Lei; Zhang, Junliang; Dong, Xiaojing; Liu, Pengyu; Chen, Daijie

    2016-01-01

    Glycopeptides such as vancomycin and telavancin are essential for treating infections caused by Gram-positive bacteria. But the dwindling availability of new antibiotics and the emergence of resistant bacteria are making effective antibiotic treatment increasingly difficult. Ramoplanin, an inhibitor of bacterial cell wall biosynthesis, is a highly effective antibiotic against a wide range of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, vancomycin-intermediate resistant Clostridium difficile and vancomycin-resistant Enterococcus sp. Here, two tailoring enzyme genes in the biosynthesis of ramoplanin were deleted by double in-frame gene knockouts to produce new ramoplanin derivatives. The deschlororamoplanin A2 aglycone was purified and its structure was identified with LC-MS/MS. Deschlororamoplanin A2 aglycone and ramoplanin aglycone showed similar activity to ramoplanin A2. The results showed that α-1,2-dimannosyl disaccharide at Hpg11 and chlorination at Chp17 in the ramoplanin structure are not essential for its antimicrobial activity. This work provides new precursor compounds for the semisynthetic modification of ramoplanin. PMID:27149627

  3. The neuroprotective action of pyrroloquinoline quinone against glutamate-induced apoptosis in hippocampal neurons is mediated through the activation of PI3K/Akt pathway

    SciTech Connect

    Zhang Qi; Shen Mi; Ding Mei; Shen Dingding; Ding Fei

    2011-04-01

    Pyrroloquinoline quinone (PQQ), a cofactor in several enzyme-catalyzed redox reactions, possesses a potential capability of scavenging reactive oxygen species (ROS) and inhibiting cell apoptosis. In this study, we investigated the effects of PQQ on glutamate-induced cell death in primary cultured hippocampal neurons and the possible underlying mechanisms. We found that glutamate-induced apoptosis in cultured hippocampal neurons was significantly attenuated by the ensuing PQQ treatment, which also inhibited the glutamate-induced increase in Ca2+ influx, caspase-3 activity, and ROS production, and reversed the glutamate-induced decrease in Bcl-2/Bax ratio. The examination of signaling pathways revealed that PQQ treatment activated the phosphorylation of Akt and suppressed the glutamate-induced phosphorylation of c-Jun N-terminal protein kinase (JNK). And inhibition of phosphatidylinositol-3-kinase (PI3K)/Akt cascade by LY294002 and wortmannin significantly blocked the protective effects of PQQ, and alleviated the increase in Bcl-2/Bax ratio. Taken together, our results indicated that PQQ could protect primary cultured hippocampal neurons against glutamate-induced cell damage by scavenging ROS, reducing Ca2+ influx, and caspase-3 activity, and suggested that PQQ-activated PI3K/Akt signaling might be responsible for its neuroprotective action through modulation of glutamate-induced imbalance between Bcl-2 and Bax. - Research Highlights: >PQQ attenuated glutamate-induced cell apoptosis of cultured hippocampal neurons. >PQQ inhibited glutamate-induced Ca{sup 2+} influx and caspase-3 activity. >PQQ reduced glutamate-induced increase in ROS production. >PQQ affected phosphorylation of Akt and JNK signalings after glutamate injury. >PI3K/Akt was required for neuroprotection of PQQ by modulating Bcl-2/Bax ratio.

  4. Effect of MS-153, a glutamate transporter activator, on the conditioned rewarding effects of morphine, methamphetamine and cocaine in mice.

    PubMed

    Nakagawa, Takayuki; Fujio, Mayumi; Ozawa, Tohru; Minami, Masabumi; Satoh, Masamichi

    2005-01-30

    There is a body of evidence implying the involvement of the glutamatergic system in the conditioned rewarding effects of drugs of abuse. It is recognized that the release of extracellular glutamate from nerve terminals is counterbalanced by the functions of neuronal and glial glutamate transporters. In the present study, we investigated the effects of (R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline (MS-153), a glutamate transporter activator, on the induction of the conditioned place preference to morphine, methamphetamine and cocaine in mice. In the conditioned place preference paradigm, mice were conditioned with repeated subcutaneous injections of morphine (5 mg/kg), methamphetamine (2 mg/kg) or cocaine (8 mg/kg) in combination with or without MS-153 (3 and 10 mg/kg). Co-administration of MS-153 at a dose of 10 mg/kg, but not 3 mg/kg, significantly attenuated the induction of conditioned place preference to morphine, methamphetamine and cocaine. However, MS-153 itself produced neither conditioned place preference nor aversion. On the other hand, co-administration of MS-153 (10 mg/kg) did not alter the acute locomotor activation elicited by a single injection of morphine, methamphetamine and cocaine. These results suggest that MS-153, a glutamate transporter activator, has an inhibitory effect on the conditioned rewarding effects of morphine, methamphetamine and cocaine without affecting their acute locomotor responses.

  5. Dynamic changes in gamma-aminobutyric acid and glutamate decarboxylase activity in oats (Avena nuda L.) during steeping and germination.

    PubMed

    Xu, Jian Guo; Hu, Qing Ping; Duan, Jiang Lian; Tian, Cheng Rui

    2010-09-01

    Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the central nervous system and provides beneficial effects for human and other animals health. To accumulate GABA, samples from two different naked oat cultivars, Baiyan II and Bayou I, were steeped and germinated in an incubator. The content of GABA and glutamic acid as well as the activity of the glutamate decarboxylase (GAD) in oats during steeping and germination were investigated with an amino acid automatic analyzer. Compared with raw groats, an increase in GABA content of oat groats during steeping and germination was continuously observed for two oat cultivars. The activity of GAD increased greatly at the end of steeping and the second stage of germination for Baiyan II and Bayou I, respectively. Glutamic acid content of treated oat groats was significantly lower than that in raw groats until the later period of germination. GABA was correlated (p<0.01) significantly and positively with the glutamic acid rather than GAD activity in the current study. The results indicates that steeping and germination process under highly controlled conditions can effectively accumulate the GABA in oat groats for Baiyan II and Bayou I, which would greatly facilitate production of nutraceuticals or food ingredients that enable consumers to gain greater access to the health benefits of oats. However, more assays need to be further performed with more oat cultivars.

  6. Active experiments, magnetospheric modification, and a naturally occurring analogue

    NASA Technical Reports Server (NTRS)

    Kivelson, M. G.; Russell, C. T.

    1973-01-01

    Recently, a scheme has been proposed which would modify the magnetosphere by injecting plasma near the equator beyond the plasmapause and initiating wave-particle instabilities. The expected effects have been examined theoretically. Injection of plasma into this region is also a naturally occurring phenomenon produced by the cross-tail electric fields which are associated with geomagnetic activity. For further investigation of magnetospheric instabilities, the advantages of examining artificially injected plasma (control of time and location of injection and of the volume of plasma injected) contrast with the advantages of studying natural enhancements (no extra payload, frequent occurrence). Thus, the two types of experiments are complementary. In preliminary studies of natural plasma enhancements both ULF and ELF emissions have been observed. The ELF noise is consistent with generation by the electron cyclotron instability.

  7. Topiramate protects against glutamate excitotoxicity via activating BDNF/TrkB-dependent ERK pathway in rodent hippocampal neurons.

    PubMed

    Mao, Xiao-Yuan; Cao, Yong-Gang; Ji, Zhong; Zhou, Hong-Hao; Liu, Zhao-Qian; Sun, Hong-Li

    2015-07-01

    Topiramate (TPM) was previously found to have neuroprotection against neuronal injury in epileptic and ischemic models. However, whether TPM protects against glutamate-induced excitotoxicity in hippocampal neurons is elusive. Our present work aimed to evaluate the protective effect of TPM against glutamate toxicity in hippocampal neurons and further figure out the potential molecular mechanisms. The in vitro glutamate excitotoxic model was prepared with 125μM glutamate for 20min. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) analysis and Hoechst 33342 staining were conducted to detect neuronal survival. The protein expressions of brain-derived neurotrophic factor (BDNF), TrkB, mitogen-activated protein kinase (MAPK) cascade (including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 MAPK), cyclic AMP response element binding protein (CREB), Bcl-2, Bax and β-actin were detected via Western blot assay. Our results demonstrated that TPM protected hippocampal neurons from glutamate toxicity. Meanwhile, the pretreatment of TPM for 10min significantly prevented the down-regulation of BDNF and the phosphorylation of TrkB. Furthermore, the elevation of phosphorylated EKR expression was significantly inhibited after blockade of TrkB by TrkB IgG, while no alterations of phosphorylated JNK and p38 MAPK were found in the cultured hippocampal neurons. Besides, it was also found that the enhanced phosphorylation of CREB was evidently reversed under excitotoxic conditions after treating with U0126 (the selective inhibitor of ERK). The protein level of Bcl-2 was also observed to be remarkably increased after TPM treatment. In conclusion, these findings implicate that TPM exerts neuroprotective effects against glutamate excitotoxicity in hippocampal neurons and its protection may be modulated through BDNF/TrkB-dependent ERK pathway.

  8. Preferential binding of allosteric modulators to active and inactive conformational states of metabotropic glutamate receptors

    PubMed Central

    Yanamala, Naveena; Tirupula, Kalyan C; Klein-Seetharaman, Judith

    2008-01-01

    Metabotropic glutamate receptors (mGluRs) are G protein coupled receptors that play important roles in synaptic plasticity and other neuro-physiological and pathological processes. Allosteric mGluR ligands are particularly promising drug targets because of their modulatory effects – enhancing or suppressing the response of mGluRs to glutamate. The mechanism by which this modulation occurs is not known. Here, we propose the hypothesis that positive and negative modulators will differentially stabilize the active and inactive conformations of the receptors, respectively. To test this hypothesis, we have generated computational models of the transmembrane regions of different mGluR subtypes in two different conformations. The inactive conformation was modeled using the crystal structure of the inactive, dark state of rhodopsin as template and the active conformation was created based on a recent model of the light-activated state of rhodopsin. Ligands for which the nature of their allosteric effects on mGluRs is experimentally known were docked to the modeled mGluR structures using ArgusLab and Autodock softwares. We find that the allosteric ligand binding pockets of mGluRs are overlapping with the retinal binding pocket of rhodopsin, and that ligands have strong preferences for the active and inactive states depending on their modulatory nature. In 8 out of 14 cases (57%), the negative modulators bound the inactive conformations with significant preference using both docking programs, and 6 out of 9 cases (67%), the positive modulators bound the active conformations. Considering results by the individual programs only, even higher correlations were observed: 12/14 (86%) and 8/9 (89%) for ArgusLab and 10/14 (71%) and 7/9 (78%) for AutoDock. These findings strongly support the hypothesis that mGluR allosteric modulation occurs via stabilization of different conformations analogous to those identified in rhodopsin where they are induced by photochemical isomerization

  9. Retour aux sources: defining the structural basis of glutamate receptor activation.

    PubMed

    Dawe, G Brent; Aurousseau, Mark R; Daniels, Bryan A; Bowie, Derek

    2015-01-01

    Ionotropic glutamate receptors (iGluRs) are the major excitatory neurotransmitter receptor in the vertebrate CNS and, as a result, their activation properties lie at the heart of much of the neuronal network activity observed in the developing and adult brain. iGluRs have also been implicated in many nervous system disorders associated with postnatal development (e.g. autism, schizophrenia), cerebral insult (e.g. stroke, epilepsy), and disorders of the ageing brain (e.g. Alzheimer's disease, Parkinsonism). In view of this, an emphasis has been placed on understanding how iGluRs activate and desensitize in functional and structural terms. Early structural models of iGluRs suggested that the strength of the agonist response was primarily governed by the degree of closure induced in the ligand-binding domain (LBD). However, recent studies have suggested a more nuanced role for the LBD with current evidence identifying the iGluR LBD interface as a "hotspot" regulating agonist behaviour. Such ideas remain to be consolidated with recently solved structures of full-length iGluRs to account for the global changes that underlie channel activation and desensitization.

  10. Stimulation of endocannabinoid formation in brain slice cultures through activation of group I metabotropic glutamate receptors.

    PubMed

    Jung, Kwang-Mook; Mangieri, Regina; Stapleton, Christopher; Kim, Janet; Fegley, Darren; Wallace, Matthew; Mackie, Ken; Piomelli, Daniele

    2005-11-01

    Activation of group I metabotropic glutamate (mGlu) receptors drives the endocannabinoid system to cause both short- and long-term changes of synaptic strength in the striatum, hippocampus, and other brain areas. Although there is strong electrophysiological evidence for a role of endocannabinoid release in mGlu receptor-dependent plasticity, the identity of the endocannabinoid transmitter mediating this phenomenon remains undefined. In this study, we show that activation of group I mGlu receptors triggers the biosynthesis of the endocannabinoid 2-arachidonoylglycerol (2-AG), but not anandamide, in primary cultures of corticostriatal and hippocampal slices prepared from early postnatal rat brain. Pharmacological studies suggest that 2-AG biosynthesis is initiated by activation of mGlu5 receptors, is catalyzed by phospholipase C (PLC) and 1,2-diacylglycerol lipase (DGL) activities, and is dependent on intracellular Ca2+ ions. Realtime polymerase chain reaction and immunostaining analyses indicate that DGL-beta is the predominant DGL isoform expressed in corticostriatal and hippocampal slices and that this enzyme is highly expressed in striatal neurons, where it is colocalized with PLC-beta1. The results suggest that 2-AG is a primary endocannabinoid mediator of mGlu receptor-dependent neuronal plasticity.

  11. Design and activity of novel lactoferrampin analogues against O157:H7 enterohemorrhagic Escherichia coli.

    PubMed

    Cruz, Jenniffer; Ortiz, Claudia; Guzmán, Fanny; Cárdenas, Constanza; Fernandez-Lafuente, Roberto; Torres, Rodrigo

    2014-04-01

    Lactoferrampin 265-284 (LFampin 265-284) is a peptide consisting of residues 265-284 of N1-domain of bovine Lactoferrin (LF). This peptide has several cationic groups in the C-terminal lobe, exhibiting an antibacterial activity against a wide range of microorganisms. However, LFampin 265-284 exhibits low antimicrobial activity against the O157:H7 enterohaemorrhagic Escherichia coli (EHEC O157:H7) when compared with Lactoferrin chimera and Lactoferricin. Here, we have designed three analogues of LFampin 265-284 based on the distribution of cationic groups, hydrophobicity, size, and sequence. Analogues were synthesized by solid phase chemistry using Fmoc methodology obtaining peptides with 95% purity. All peptides maintain the ability to adopt helical conformations (checked by circular dichroism spectra and molecular simulations). Some of these analogues exhibited a significant increase in antimicrobial activity by counting colony forming units against EHEC O157:H7 compared to native LFampin 265-284, with MIC of 10 and 40 µM for 264G-D265K and 264G-D265K/S272R, respectively. The incorporation of a GKLI sequence in the N-terminal lobe increased dramatically its antibacterial activity, an effect which has been attributed to the addition of cationic groups in the N-terminal side that may stabilize the helical conformation of the new designed peptides.

  12. A nonlinear dynamical analogue model of geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Klimas, A. J.; Baker, D. N.; Roberts, D. A.; Fairfield, D. H.; Buechner, J.

    1992-01-01

    Consideration is given to the solar wind-magnetosphere interaction within the framework of deterministic nonlinear dynamics. An earlier dripping faucet analog model of the low-dimensional solar wind-magnetosphere system is reviewed, and a plasma physical counterpart to that model is constructed. A Faraday loop in the magnetotail is considered, and the relationship of electric potentials on the loop to changes in the magnetic flux threading the loop is developed. This approach leads to a model of geomagnetic activity which is similar to the earlier mechanical model but described in terms of the geometry and plasma contents of the magnetotail. The model is characterized as an elementary time-dependent global convection model. The convection evolves within a magnetotail shape that varies in a prescribed manner in response to the dynamical evolution of the convection. The result is a nonlinear model capable of exhibiting a transition from regular to chaotic loading and unloading. The model's behavior under steady loading and also some elementary forms of time-dependent loading is discussed.

  13. Synthesis, antidepressant and antimicrobial activities of some novel stearic acid analogues.

    PubMed

    Jubie, Selvaraj; Ramesh, Patil Nilesh; Dhanabal, Palanichamy; Kalirajan, Rajagopal; Muruganantham, Nithyanantham; Antony, Anthoniswamy Shanish

    2012-08-01

    Stearic acid, a saturated fatty acid was isolated from the microalga Spirulina platensis. Some novel stearic acid analogues having 1,3,4-oxadiazole, 1,2,4-triazole and 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole are synthesized and characterized by IR, NMR and mass spectral analysis. All the synthesized compounds were screened for antimicrobial activity by using cup plate method. The synthesized compounds have been further screened for their antidepressant activity in swiss albino mice by forced swim test (FST), midbrain dopamine has been estimated and quantified. All the compounds showed good antimicrobial activity and compound 6 showed significant antidepressant activity.

  14. The structure, synthesis, and immunomodulating activity of bacterial lipopeptides and their analogues

    NASA Astrophysics Data System (ADS)

    Ousanova, Mariya P.; Sebyakin, Yurii L.

    1997-10-01

    The current state and prospects for the use of natural lipopeptides and their synthetic analogues in the study of fine mechanisms of functioning of complex biological systems and in the solution of various problems of biochemistry and medicine are considered. The results of investigations related to the synthesis and biological activity of lipopeptides are summarised. The data on the application of lipopeptides as components of synthetic vaccines and antitumour drugs are discussed. The bibliography includes 71 references.

  15. Eco-Friendly Insecticide Discovery via Peptidomimetics: Design, Synthesis, and Aphicidal Activity of Novel Insect Kinin Analogues.

    PubMed

    Zhang, Chuanliang; Qu, Yanyan; Wu, Xiaoqing; Song, Dunlun; Ling, Yun; Yang, Xinling

    2015-05-13

    Insect kinin neuropeptides are pleiotropic peptides that are involved in the regulation of hindgut contraction, diuresis, and digestive enzyme release. They share a common C-terminal pentapeptide sequence of Phe(1)-Xaa(2)-Yaa(3)-Trp(4)-Gly(5)-NH2 (where Xaa(2) = His, Asn, Phe, Ser, or Tyr; Yaa(3) = Pro, Ser, or Ala). Recently, the aphicidal activity of insect kinin analogues has attracted the attention of researchers. Our previous work demonstrated that the sequence-simplified insect kinin pentapeptide analogue Phe-Phe-[Aib]-Trp-Gly-NH2 could retain good aphicidal activity and be the lead compound for the further discovery of eco-friendly insecticides which encompassed a broad array of biochemicals derived from micro-organisms and other natural sources. Using the peptidomimetics strategy, we chose Phe-Phe-[Aib]-Trp-Gly-NH2 as the lead compound, and we designed and synthesized three series, including 31 novel insect kinin analogues. The aphicidal activity of the new analogues against soybean aphid was determined. The results showed that all of the analogues exhibited aphicidal activity. Of particular interest was the analogue II-1, which exhibited improved aphicidal activity with an LC50 of 0.019 mmol/L compared with the lead compound (LC50 = 0.045 mmol/L) or the commercial insecticide pymetrozine (LC50 = 0.034 mmol/L). This suggests that the analogue II-1 could be used as a new lead for the discovery of potential eco-friendly insecticides.

  16. Characterization of the glutamate dehydrogenase activity of Gigantocotyle explanatum and Gastrothylax crumenifer (Trematoda: Digenea).

    PubMed

    Abidi, S M A; Khan, P; Saifullah, M K

    2009-12-01

    Glutamate dehydrogenase (GLDH) (EC 1.4.1.3) is a ubiquitous enzyme, which is present at the protein and carbohydrate metabolism crossroads. The enzyme activity was investigated in biliary and rumen amphistomes, Gigantocotyle explanatum and Gastrothylax crumenifer, respectively, infecting the Indian water buffalo Bubalus bubalis. The enzyme activity was consistently higher in G. explanatum as compared to G. crumenifer, where NAD(H) was utilized as coenzyme and the pH optima was recorded at 8. The K(m) and V(max) values for α-ketoglutarate were 2.1 mM and 9.09 units in G. explanatum, whereas 3.03 mM and 1.90 units in G. crumenifer, respectively. Among the allosteric modulator nucleotides, AMP, ADP, ATP, GMP, CMP and UMP, only AMP enhanced GLDH activity in G. crumenifer while ADP was stimulatory in G. explanatum. The amino acid leucine stimulated the GLDH activity in both the amphistomes while alanine was stimulatory only in G. crumenifer. Pronounced interspecific differences in response to different metabolic inhibitors like diethyldithiocarbamate, semicarbazide hydrochloride and mercurial ions were also observed. The osmotic stress alters the enzyme activity, particularly in hypertonic saline the GLDH activity increased significantly (p < 0.01) in G. explanatum, while insignificant effects were observed in rumen dwelling G. crumenifer. Histoenzymology revealed region/tissue specific distribution of GLDH with prominent staining in tissues like vitellaria, lymph system and tegument/subtegument, thus showing specific distribution of GLDH indicating differential metabolic state. Such intergeneric differences in GLDH activity could also be a consequence of occupying different microenvironments within the same host.

  17. Three-dimensional quantitative structure-activity relationship study on antioxidant capacity of curcumin analogues

    NASA Astrophysics Data System (ADS)

    Chen, Bohong; Zhu, Zhibo; Chen, Min; Dong, Wenqi; Li, Zhen

    2014-03-01

    A comparative molecular similarity indices analysis (CoMSIA) was performed on a set of 27 curcumin-like diarylpentanoid analogues with the radical scavenging activities. A significant cross-validated correlation coefficient Q2 (0.784), SEP (0.042) for CoMSIA were obtained, indicating the statistical significance of the correlation. Further we adopt a rational approach toward the selection of substituents at various positions in our scaffold,and finally find the favored and disfavoured regions for the enhanced antioxidative activity. The results have been used as a guide to design compounds that, potentially, have better activity against oxidative damage.

  18. Synthesis and κ-Opioid Receptor Activity of Furan-Substituted Salvinorin A Analogues

    PubMed Central

    2015-01-01

    The neoclerodane diterpene salvinorin A, found in the leaves of Salvia divinorum, is a potent κ-opioid receptor agonist, making it an attractive scaffold for development into a treatment for substance abuse. Although several successful semisynthetic studies have been performed to elucidate structure–activity relationships, the lack of analogues with substitutions to the furan ring of salvinorin A has prevented a thorough understanding of its role in binding to the κ-opioid receptor. Herein we report the synthesis of several salvinorin A derivatives with modified furan rings. Evaluation of these compounds in a functional assay indicated that sterically less demanding substitutions are preferred, suggesting the furan ring is bound in a congested portion of the binding pocket. The most potent of the analogues successfully reduced drug-seeking behavior in an animal model of drug-relapse without producing the sedation observed with other κ-opioid agonists. PMID:25426797

  19. Anti-herpetic and anti-dengue activity of abietane ferruginol analogues synthesized from (+)-dehydroabietylamine.

    PubMed

    Roa-Linares, Vicky C; Brand, Yaneth M; Agudelo-Gomez, Lee S; Tangarife-Castaño, Verónica; Betancur-Galvis, Liliana A; Gallego-Gomez, Juan C; González, Miguel A

    2016-01-27

    The abietane-type diterpenoid (+)-ferruginol (1), a bioactive compound isolated from several plants, has attracted much attention as consequence of its pharmacological properties, which includes antibacterial, antifungal, antimicrobial, cardioprotective, anti-oxidative, anti-plasmodial, leishmanicidal, anti-ulcerogenic, anti-inflammatory and antitumor actions. In this study, we report on the antiviral evaluation of ferruginol (1) and several analogues synthesized from commercial (+)-dehydroabietylamine. Thus, the activity against Human Herpesvirus type 1, Human Herpesvirus type 2 and Dengue Virus type 2, was studied. Two ferruginol analogues showed high antiviral selectivity index and reduced viral plaque-size in post-infection stages against both Herpes and Dengue viruses. A promising lead, compound 8, was ten-fold more potent (EC50 = 1.4 μM) than the control ribavirin against Dengue Virus type 2. Our findings suggest that the 12-hydroxyabieta-8,11,13-triene skeleton, which is characteristic of the diterpenoid ferruginol (1), is an interesting molecular scaffold for development of novel antivirals. In addition, the cytotoxic and antifungal activities of the synthesized ferruginol analogues have also been investigated. (©)20155 Elsevier Science. All rights reserved. PMID:26638041

  20. Bruchpilot and Synaptotagmin collaborate to drive rapid glutamate release and active zone differentiation.

    PubMed

    Paul, Mila M; Pauli, Martin; Ehmann, Nadine; Hallermann, Stefan; Sauer, Markus; Kittel, Robert J; Heckmann, Manfred

    2015-01-01

    The active zone (AZ) protein Bruchpilot (Brp) is essential for rapid glutamate release at Drosophila melanogaster neuromuscular junctions (NMJs). Quantal time course and measurements of action potential-waveform suggest that presynaptic fusion mechanisms are altered in brp null mutants (brp(69) ). This could account for their increased evoked excitatory postsynaptic current (EPSC) delay and rise time (by about 1 ms). To test the mechanism of release protraction at brp(69) AZs, we performed knock-down of Synaptotagmin-1 (Syt) via RNAi (syt(KD) ) in wildtype (wt), brp(69) and rab3 null mutants (rab3(rup) ), where Brp is concentrated at a small number of AZs. At wt and rab3(rup) synapses, syt(KD) lowered EPSC amplitude while increasing rise time and delay, consistent with the role of Syt as a release sensor. In contrast, syt(KD) did not alter EPSC amplitude at brp(69) synapses, but shortened delay and rise time. In fact, following syt(KD) , these kinetic properties were strikingly similar in wt and brp(69) , which supports the notion that Syt protracts release at brp(69) synapses. To gain insight into this surprising role of Syt at brp(69) AZs, we analyzed the structural and functional differentiation of synaptic boutons at the NMJ. At 'tonic' type Ib motor neurons, distal boutons contain more AZs, more Brp proteins per AZ and show elevated and accelerated glutamate release compared to proximal boutons. The functional differentiation between proximal and distal boutons is Brp-dependent and reduced after syt(KD) . Notably, syt(KD) boutons are smaller, contain fewer Brp positive AZs and these are of similar number in proximal and distal boutons. In addition, super-resolution imaging via dSTORM revealed that syt(KD) increases the number and alters the spatial distribution of Brp molecules at AZs, while the gradient of Brp proteins per AZ is diminished. In summary, these data demonstrate that normal structural and functional differentiation of Drosophila AZs requires

  1. Bruchpilot and Synaptotagmin collaborate to drive rapid glutamate release and active zone differentiation

    PubMed Central

    Paul, Mila M.; Pauli, Martin; Ehmann, Nadine; Hallermann, Stefan; Sauer, Markus; Kittel, Robert J.; Heckmann, Manfred

    2015-01-01

    The active zone (AZ) protein Bruchpilot (Brp) is essential for rapid glutamate release at Drosophila melanogaster neuromuscular junctions (NMJs). Quantal time course and measurements of action potential-waveform suggest that presynaptic fusion mechanisms are altered in brp null mutants (brp69). This could account for their increased evoked excitatory postsynaptic current (EPSC) delay and rise time (by about 1 ms). To test the mechanism of release protraction at brp69 AZs, we performed knock-down of Synaptotagmin-1 (Syt) via RNAi (sytKD) in wildtype (wt), brp69 and rab3 null mutants (rab3rup), where Brp is concentrated at a small number of AZs. At wt and rab3rup synapses, sytKD lowered EPSC amplitude while increasing rise time and delay, consistent with the role of Syt as a release sensor. In contrast, sytKD did not alter EPSC amplitude at brp69 synapses, but shortened delay and rise time. In fact, following sytKD, these kinetic properties were strikingly similar in wt and brp69, which supports the notion that Syt protracts release at brp69synapses. To gain insight into this surprising role of Syt at brp69 AZs, we analyzed the structural and functional differentiation of synaptic boutons at the NMJ. At ‘tonic’ type Ib motor neurons, distal boutons contain more AZs, more Brp proteins per AZ and show elevated and accelerated glutamate release compared to proximal boutons. The functional differentiation between proximal and distal boutons is Brp-dependent and reduced after sytKD. Notably, sytKD boutons are smaller, contain fewer Brp positive AZs and these are of similar number in proximal and distal boutons. In addition, super-resolution imaging via dSTORM revealed that sytKD increases the number and alters the spatial distribution of Brp molecules at AZs, while the gradient of Brp proteins per AZ is diminished. In summary, these data demonstrate that normal structural and functional differentiation of Drosophila AZs requires concerted action of Brp and Syt. PMID

  2. Synthesis, spectral characterization and larvicidal activity of acridin-1(2H)-one analogues

    NASA Astrophysics Data System (ADS)

    Subashini, R.; Bharathi, A.; Roopan, Selvaraj Mohana; Rajakumar, G.; Abdul Rahuman, A.; Gullanki, Pavan Kumar

    Acridin-1(2H)-one analogue of 7-chloro-3,4-dihydro-9-phenyl-2-[(pyridine-2yl) methylene] acridin-1(2H)-one, 5 was prepared by using 7-chloro-3,4-dihydro-9-phenylacridin-1(2H)-one, 3 and picolinaldehyde, 4 in the presence of KOH at room temperature. These compounds were characterized by analytical and spectral analyses. The purpose of the present study was to assess the efficacy of larvicidal and repellent activity of synthesized 7-chloro-3,4-dihydro-9-phenyl-acridin-1(2H)-one analogues such as compounds 3 and 5 against the early fourth instar larvae of filariasis vector, Culex quinquefasciatus and Japanese encephalitis vector, Culex gelidus (Diptera: Culicidae). The compound exhibited high larvicidal effects at 50 mg/L against both the mosquitoes with LC50 values of 25.02 mg/L (r2 = 0.998) and 26.40 mg/L (r2 = 0.988) against C. quinquefasciatus and C. gelidus, respectively. The 7-chloro-3,4-dihydro-9-phenyl-acridin-1(2H)-one analogues that are reported for the first time to our best of knowledge can be better explored for the control of mosquito population. This is an ideal ecofriendly approach for the control of Japanese encephalitis vectors, C. quinquefasciatus and C. gelidus.

  3. Aniline mustard analogues of the DNA-intercalating agent amsacrine: DNA interaction and biological activity.

    PubMed

    Fan, J Y; Valu, K K; Woodgate, P D; Baguley, B C; Denny, W A

    1997-04-01

    Two series of analogues of the clinical antileukemic drug and DNA-intercalating ligand amsacrine have been prepared, containing aniline mustard sidechains of varying reactivity, linked either at the 4-position of the intercalating acridine chromophore (type A) or at the 1'-position of the 9-anilino group (type B). DNase I footprinting assays showed that compounds of type B had stronger reversible binding to DNA than did compounds of type A. Compounds of each type showed similar patterns of alkylation-induced cleavage of DNA, and alkylate at the N7 of guanines in runs of guanines (similar to the pattern for untargeted mustards) as well as some adenines. Both classes of compounds crosslinked DNA, although those bearing relatively inactive mustards did so only at high drug/base pair ratios. However, while the patterns of DNA alkylation were broadly similar, the compounds were considerably more cytotoxic than analogous untargeted mustards. Comparison of their cytotoxicities in wild-type and DNA repair-deficient lines indicated this toxicity was due to DNA crosslinks (except for the least reactive SO2-linked mustards). The 4-linked analogues showed slightly higher in vivo antileukemic activity than the corresponding 1'-linked analogues.

  4. Biological and chemical study of fused tri- and tetracyclic indazoles and analogues with important antiparasitic activity

    NASA Astrophysics Data System (ADS)

    Díaz-Urrutia, Christian A.; Olea-Azar, Claudio A.; Zapata, Gerald A.; Lapier, Michel; Mura, Francisco; Aguilera-Venegas, Benjamín; Arán, Vicente J.; López-Múñoz, Rodrigo A.; Maya, Juan D.

    A series of fused tri- and tetracyclic indazoles and analogues compounds (NID) with potential antiparasitic effects were studied using voltamperometric and spectroscopic techniques. Nitroanion radicals generated by cyclic voltammetry were characterized by electron spin resonance spectroscopy (ESR) and their spectral lines were explained and analyzed using simulated spectra. In addition, we examined the interaction between radical species generated from nitroindazole derivatives and glutathione (GSH). Biological assays such as activity against Trypanosoma cruzi and cytotoxicity against macrophages were carried out. Finally, spin trapping and molecular modeling studies were also done in order to elucidate the potentials action mechanisms involved in the trypanocidal activity.

  5. Biological and chemical study of fused tri- and tetracyclic indazoles and analogues with important antiparasitic activity.

    PubMed

    Díaz-Urrutia, Christian A; Olea-Azar, Claudio A; Zapata, Gerald A; Lapier, Michel; Mura, Francisco; Aguilera-Venegas, Benjamín; Arán, Vicente J; López-Múñoz, Rodrigo A; Maya, Juan D

    2012-09-01

    A series of fused tri- and tetracyclic indazoles and analogues compounds (NID) with potential antiparasitic effects were studied using voltamperometric and spectroscopic techniques. Nitroanion radicals generated by cyclic voltammetry were characterized by electron spin resonance spectroscopy (ESR) and their spectral lines were explained and analyzed using simulated spectra. In addition, we examined the interaction between radical species generated from nitroindazole derivatives and glutathione (GSH). Biological assays such as activity against Trypanosoma cruzi and cytotoxicity against macrophages were carried out. Finally, spin trapping and molecular modeling studies were also done in order to elucidate the potentials action mechanisms involved in the trypanocidal activity.

  6. Antifungal agents, Part 11. Biphenyl analogues of naftifine: synthesis and antifungal activities.

    PubMed

    Porretta, G C; Fioravanti, R; Biava, M; Artico, M; Villa, A; Simonetti, N

    1995-09-01

    A series of naftifine analogues having the biphenyl instead of the naphthyl moiety have been synthesized in a search devoted to study bioanalogues of clinically efficacious antifungal agents. The new derivatives were tested against Candida albicans by the direct contact method. They were also assayed against Gram-positive and Gram-negative bacteria and against some isolates of plant pathogenic fungi. Derivatives 8a, 8c, and 9a were found to be active against Candida albicans, derivative 5a was active against E. coli, a very resistant species to antimycotic agents, and derivatives 8a and 8b inhibited the plant pathogenic Rhizoctonia solani.

  7. Synthesis and antiviral activity of the carbocyclic analogue of the highly potent and selective anti-VZV bicyclo furano pyrimidines.

    PubMed

    Migliore, Marco D; Zonta, Nicola; McGuigan, Christopher; Henson, Geoffrey; Andrei, Graciela; Snoeck, Robert; Balzarini, Jan

    2007-12-27

    Carbocyclic nucleoside analogues are catabolically stable since they are resistant to phosphorolytic cleavage by pyrimidine nucleoside phosphorylase enzymes. The carbocyclic analogue (C-BCNA) of the highly potent and selective anti-VZV bicyclic nucleoside analogue (BCNA) 6-pentylphenylfuro[2,3-d]pyrimidine-2'-deoxyribose was synthesized using carbocyclic 2'-deoxyuridine as starting material. C-BCNA was found to be chemically more stable than the furano lead, but it was shown to be significantly less antivirally active than its parent nucleoside analogue. It was noted to have a 10-fold lower inhibitory activity against the VZV-encoded thymidine kinase. This reduction of activity may be attributed to the different conformation of the sugar and base, as predicted by computational studies and supported by NMR studies. However, other factors besides affinity for VZV-TK must account for the greatly reduced antiviral potency. PMID:18052321

  8. Activation of metabotropic glutamate receptor 5 in the amygdala modulates pain-like behavior.

    PubMed

    Kolber, Benedict J; Montana, Michael C; Carrasquillo, Yarimar; Xu, Jian; Heinemann, Stephen F; Muglia, Louis J; Gereau, Robert W

    2010-06-16

    The central nucleus of the amygdala (CeA) has been identified as a site of nociceptive processing important for sensitization induced by peripheral injury. However, the cellular signaling components underlying this function remain unknown. Here, we identify metabotropic glutamate receptor 5 (mGluR5) as an integral component of nociceptive processing in the CeA. Pharmacological activation of mGluRs with (R,S)-3,5-dihydroxyphenylglycine (DHPG) in the CeA of mice is sufficient to induce peripheral hypersensitivity in the absence of injury. DHPG-induced peripheral hypersensitivity is reduced via pharmacological blockade of mGluR5 or genetic disruption of mGluR5. Furthermore, pharmacological blockade or conditional deletion of mGluR5 in the CeA abrogates inflammation-induced hypersensitivity, demonstrating the necessity of mGluR5 in CeA-mediated pain modulation. Moreover, we demonstrate that phosphorylation of extracellular-signal regulated kinase 1/2 (ERK1/2) is downstream of mGluR5 activation in the CeA and is necessary for the full expression of peripheral inflammation-induced behavioral sensitization. Finally, we present evidence of right hemispheric lateralization of mGluR5 modulation of amygdalar nociceptive processing. We demonstrate that unilateral pharmacological activation of mGluR5 in the CeA produces distinct behavioral responses depending on whether the right or left amygdala is injected. We also demonstrate significantly higher levels of mGluR5 expression in the right amygdala compared with the left under baseline conditions, suggesting a potential mechanism for right hemispheric lateralization of amygdala function in pain processing. Together, these results establish an integral role for mGluR5 and ERK1/2 in nociceptive processing in the CeA. PMID:20554871

  9. Glutamate signalling in roots.

    PubMed

    Forde, Brian G

    2014-03-01

    As a signalling molecule, glutamate is best known for its role as a fast excitatory neurotransmitter in the mammalian nervous system, a role that requires the activity of a family of ionotropic glutamate receptors (iGluRs). The unexpected discovery in 1998 that Arabidopsis thaliana L. possesses a family of iGluR-related (GLR) genes laid the foundations for an assessment of glutamate's potential role as a signalling molecule in plants that is still in progress. Recent advances in elucidating the function of Arabidopsis GLR receptors has revealed similarities with iGluRs in their channel properties, but marked differences in their ligand specificities. The ability of plant GLR receptors to act as amino-acid-gated Ca(2+) channels with a broad agonist profile, combined with their expression throughout the plant, makes them strong candidates for a multiplicity of amino acid signalling roles. Although root growth is inhibited in the presence of a number of amino acids, only glutamate elicits a specific sequence of changes in growth, root tip morphology, and root branching. The recent finding that the MEKK1 gene is a positive regulator of glutamate sensitivity at the root tip has provided genetic evidence for the existence in plants of a glutamate signalling pathway analogous to those found in animals. This short review will discuss the most recent advances in understanding glutamate signalling in roots, considering them in the context of previous work in plants and animals.

  10. Evidence for synergistic control of glutamate biosynthesis by glutamate dehydrogenases and glutamate in Bacillus subtilis.

    PubMed

    Stannek, Lorena; Thiele, Martin J; Ischebeck, Till; Gunka, Katrin; Hammer, Elke; Völker, Uwe; Commichau, Fabian M

    2015-09-01

    In the Gram-positive bacterium, Bacillus subtilis glutamate is synthesized by the glutamine synthetase and the glutamate synthase (GOGAT). During growth with carbon sources that exert carbon catabolite repression, the rocG glutamate dehydrogenase (GDH) gene is repressed and the transcription factor GltC activates the expression of the GOGAT encoding gltAB genes. In the presence of amino acids of the glutamate family, the GDH RocG is synthesized and the enzyme prevents GltC from binding to DNA. The dual control of glutamate biosynthesis allows the efficient utilization of the available nutrients. Here we provide genetic and biochemical evidence that, like RocG, also the paralogous GDH GudB can inhibit the transcription factor GltC, thereby controlling glutamate biosynthesis. Contradictory previous observations show that high level of GDH activity does not result in permanent inhibition of GltC. By controlling the intracellular levels of glutamate through feeding with exogenous arginine, we observed that the GDH-dependent control of GltC and thus expression of the gltAB genes inversely correlates with the glutamate pool. These results suggest that the B. subtilis GDHs RocG and GudB in fact act as glutamate sensors. In conclusion, the GDH-mediated control of glutamate biosynthesis seems to depend on the intracellular glutamate concentration. PMID:25711804

  11. Synthesis and structure-activity relationship of cytotoxic marine cyclodepsipeptide IB-01212 analogues.

    PubMed

    Cruz, Luis J; Francesch, Andres; Cuevas, Carmen; Albericio, Fernando

    2007-07-01

    Several recently discovered marine products have remarkable in vitro and in vivo anticancer profiles against a wide range of tumor cell lines. Some of these compounds are currently in clinical trials. These compounds show complex structures and mechanisms of action of interest. Herein, we describe the preparation of a series of totally synthetic molecules that are structurally related to the natural marine product IB-01212 and evaluated them as antitumor agents. For this, total solid-phase syntheses of the products were performed in parallel by two distinct routes: linear synthesis and convergent synthesis. Structural modifications were introduced in several residue positions to afford 21 IB-01212 analogues for structure-relationship studies. An increase in the number of methyl groups in the macrocycle enhanced cytotoxic activity. Also, the replacement of an ester bond by an amide bond favored antitumor activity against several human cell lines. In addition, the L configuration analogues were more active against all the tumor cell lines than those containing the D configuration. A significant increase in the size and asymmetry of the macrocycle diminished biological activity with respect to that of IB-01212. These results are of great value for the discovery of new and more effective anticancer agents.

  12. Characteristics of cyanopindolol analogues active at the beta 3-adrenoceptor in rat ileum.

    PubMed Central

    Hoey, A. J.; Jackson, C. M.; Pegg, G. G.; Sillence, M. N.

    1996-01-01

    1. Cyanopindolol (CYP) is a potent antagonist at the beta 3-adrenoceptor in rat ileum. Several analogues of CYP and pindolol were synthesized that also produced antagonist effects at the beta 3-adrenoceptor. However, at high concentrations, these compounds appear to act as "partial agonists'. This study was conducted to determine the structural requirements of CYP analogues necessary for antagonist activity and to examine the possibility that the agonist effects of CYP and its analogues may occur through a mechanism independent of beta-adrenoceptor activation. 2. Analogues of CYP and pindolol were tested for antagonist activity in rat ileum in which the beta 1- and beta 2-adrenoceptors were blocked. Fourteen compounds were tested against (-)-isoprenaline, and four of the more potent analogues were then tested against BRL 37344. The two most potent antagonists were CYP and iodocyanopindolol. The pKb values (negative log of equilibrium dissociation constant) obtained against (-)-isoprenaline were significantly higher than those obtained against BRL 37344, but the cause of this difference is not known. 3. Several structural requirements were determined for antagonist activity. Modification at the carbon atom alpha to the secondary amine caused the antagonist potency to fall as the level of saturation was reduced. Thus, a quaternary carbon group, such as t-butyl, produced the most potent antagonist. Substitution with a large moiety such as a cyclohexyl or benzyl group reduced antagonist activity, probably due to steric hindrance. Inclusion of an electron-withdrawing group, such as a cyano or ethylester moiety, alpha to the indole nitrogen, also increased the potency. Iodination of CYP and ethylesterpindolol at the 3-position of the indole ring did not increase antagonist potency. In contrast, iodination of the almost inactive analogues produced a significant increase in potency, suggesting that a beneficial electronic effect on the indole ring imparted by the iodo

  13. Synthesis and Anti-Tuberculosis Activity of the Marine Natural Product Caulerpin and Its Analogues

    PubMed Central

    Canché Chay, Cristina I.; Gómez Cansino, Rocío; Espitia Pinzón, Clara I.; Torres-Ochoa, Rubén O.; Martínez, Roberto

    2014-01-01

    Caulerpin (1a), a bis-indole alkaloid from the marine algal Caulerpa sp., was synthesized in three reaction steps with an overall yield of 11%. The caulerpin analogues (1b–1g) were prepared using the same synthetic pathway with overall yields between 3% and 8%. The key reaction involved a radical oxidative aromatic substitution involving xanthate (3) and 3-formylindole compounds (4a–4g). All bis-indole compounds synthesized were evaluated against the Mycobacterium tuberculosis strain H37Rv, and 1a was found to display excellent activity (IC50 0.24 µM). PMID:24681629

  14. Unciaphenol, an Oxygenated Analogue of the Bergman Cyclization Product of Uncialamycin Exhibits Anti-HIV Activity.

    PubMed

    Williams, David E; Bottriell, Helen; Davies, Julian; Tietjen, Ian; Brockman, Mark A; Andersen, Raymond J

    2015-11-01

    Unciaphenol (2), an oxygenated analogue of the Bergman cyclization product of the enediyne uncialamycin (1), has been isolated along with 1 from cultures of the actinomycete Streptomyces uncialis. It is proposed that the C-22 OH substituent in 2 might arise from the attack of a nucleophilic oxygen species on the p-benzyne diradical intermediate IA in the Bergman cyclization of 1. 2 shows in vitro anti-HIV activity against viral strains that are resistant to clinically utilized anti-retroviral therapies.

  15. Antimicrobial activities of 3-amino- and polyaminosterol analogues of squalamine and trodusquemine.

    PubMed

    Salmi, Chanaz; Loncle, Celine; Vidal, Nicolas; Laget, Michéle; Letourneux, Yves; Brunel, Jean Michel

    2008-12-01

    A series of 3-amino- and polyaminosterol analogues of squalamine and trodusquemine were synthesized and evaluated for their in vitro antimicrobial properties against human pathogens. The activity was highly dependent on the structure of the different compounds involved and the best results were obtained with aminosterol derivatives 4b, 4e, 8b, 8e and 8n exhibiting minimum inhibitory concentrations (MICs) against yeasts, Gram positive and Gram negative bacteria at average concentrations of 3.12-12.5 microM. PMID:19005944

  16. Glutamate transporters alterations in the reorganizing dentate gyrus are associated with progressive seizure activity in chronic epileptic rats.

    PubMed

    Gorter, Jan A; Van Vliet, Erwin A; Proper, Evelien A; De Graan, Pierre N E; Ghijsen, Wim E J M; Lopes Da Silva, Fernando H; Aronica, Eleonora

    2002-01-21

    The expression of glial and neuronal glutamate transporter proteins was investigated in the hippocampal region at different time points after electrically induced status epilepticus (SE) in the rat. This experimental rat model for mesial temporal lobe epilepsy is characterized by cell loss, gliosis, synaptic reorganization, and chronic seizures after a latent period. Despite extensive gliosis, immunocytochemistry revealed only an up-regulation of both glial transporters localized at the outer aspect of the inner molecular layer (iml) in chronic epileptic rats. The neuronal EAAC1 transporter was increased in many somata of individual CA1-3 neurons and granule cells that had survived after SE; this up-regulation was still present in the chronic epileptic phase. In contrast, a permanent decrease of EAAC1 immunoreactivity was observed in the iml of the dentate gyrus. This permanent decrease in EAAC1 expression, which was only observed in rats that experienced progressive spontaneous seizure activity, could lead to abnormal glutamate levels in the iml once new abnormal glutamatergic synaptic contacts are formed by means of sprouted mossy fibers. Considering the steady growth of reorganizing mossy fibers in the iml, the absence of a glutamate reuptake mechanism in this region could contribute to progression of spontaneous seizure activity, which occurs with a similar time course.

  17. Pyridoxine Supplementation Improves the Activity of Recombinant Glutamate Decarboxylase and the Enzymatic Production of Gama-Aminobutyric Acid

    PubMed Central

    Huang, Yan; Su, Lingqia; Wu, Jing

    2016-01-01

    Glutamate decarboxylase (GAD) catalyzes the irreversible decarboxylation of L-glutamate to the valuable food supplement γ-aminobutyric acid (GABA). In this study, GAD from Escherichia coli K12, a pyridoxal phosphate (PLP)-dependent enzyme, was overexpressed in E. coli. The GAD produced in media supplemented with 0.05 mM soluble vitamin B6 analog pyridoxine hydrochloride (GAD-V) activity was 154.8 U mL-1, 1.8-fold higher than that of GAD obtained without supplementation (GAD-C). Purified GAD-V exhibited increased activity (193.4 U mg-1, 1.5-fold higher than that of GAD-C), superior thermostability (2.8-fold greater than that of GAD-C), and higher kcat/Km (1.6-fold higher than that of GAD-C). Under optimal conditions in reactions mixtures lacking added PLP, crude GAD-V converted 500 g L-1 monosodium glutamate (MSG) to GABA with a yield of 100%, and 750 g L-1 MSG with a yield of 88.7%. These results establish the utility of pyridoxine supplementation and lay the foundation for large-scale enzymatic production of GABA. PMID:27438707

  18. Activation of presynaptic oxytocin receptors enhances glutamate release in the ventral hippocampus of prenatally restraint stressed rats.

    PubMed

    Mairesse, Jérôme; Gatta, Eleonora; Reynaert, Marie-Line; Marrocco, Jordan; Morley-Fletcher, Sara; Soichot, Marion; Deruyter, Lucie; Camp, Gilles Van; Bouwalerh, Hammou; Fagioli, Francesca; Pittaluga, Anna; Allorge, Delphine; Nicoletti, Ferdinando; Maccari, Stefania

    2015-12-01

    Oxytocin receptors are known to modulate synaptic transmission and network activity in the hippocampus, but their precise function has been only partially elucidated. Here, we have found that activation of presynaptic oxytocin receptor with the potent agonist, carbetocin, enhanced depolarization-evoked glutamate release in the ventral hippocampus with no effect on GABA release. This evidence paved the way for examining the effect of carbetocin treatment in "prenatally restraint stressed" (PRS) rats, i.e., the offspring of dams exposed to repeated episodes of restraint stress during pregnancy. Adult PRS rats exhibit an anxious/depressive-like phenotype associated with an abnormal glucocorticoid feedback regulation of the hypothalamus-pituitary-adrenal (HPA) axis, and, remarkably, with a reduced depolarization-evoked glutamate release in the ventral hippocampus. Chronic systemic treatment with carbetocin (1mg/kg, i.p., once a day for 2-3 weeks) in PRS rats corrected the defect in glutamate release, anxiety- and depressive-like behavior, and abnormalities in social behavior, in the HPA response to stress, and in the expression of stress-related genes in the hippocampus and amygdala. Of note, carbetocin treatment had no effect on these behavioral and neuroendocrine parameters in prenatally unstressed (control) rats, with the exception of a reduced expression of the oxytocin receptor gene in the amygdala. These findings disclose a novel function of oxytocin receptors in the hippocampus, and encourage the use of oxytocin receptor agonists in the treatment of stress-related psychiatric disorders in adult life.

  19. Pyridoxine Supplementation Improves the Activity of Recombinant Glutamate Decarboxylase and the Enzymatic Production of Gama-Aminobutyric Acid.

    PubMed

    Huang, Yan; Su, Lingqia; Wu, Jing

    2016-01-01

    Glutamate decarboxylase (GAD) catalyzes the irreversible decarboxylation of L-glutamate to the valuable food supplement γ-aminobutyric acid (GABA). In this study, GAD from Escherichia coli K12, a pyridoxal phosphate (PLP)-dependent enzyme, was overexpressed in E. coli. The GAD produced in media supplemented with 0.05 mM soluble vitamin B6 analog pyridoxine hydrochloride (GAD-V) activity was 154.8 U mL-1, 1.8-fold higher than that of GAD obtained without supplementation (GAD-C). Purified GAD-V exhibited increased activity (193.4 U mg-1, 1.5-fold higher than that of GAD-C), superior thermostability (2.8-fold greater than that of GAD-C), and higher kcat/Km (1.6-fold higher than that of GAD-C). Under optimal conditions in reactions mixtures lacking added PLP, crude GAD-V converted 500 g L-1 monosodium glutamate (MSG) to GABA with a yield of 100%, and 750 g L-1 MSG with a yield of 88.7%. These results establish the utility of pyridoxine supplementation and lay the foundation for large-scale enzymatic production of GABA. PMID:27438707

  20. II. Glutamine and glutamate.

    PubMed

    Tapiero, H; Mathé, G; Couvreur, P; Tew, K D

    2002-11-01

    plays a role in the formation and function of the cytoskeleton. Glutamine via glutamate is converted to alpha-ketoglutarate, an integral component of the citric acid cycle. It is a component of the antioxidant glutathione and of the polyglutamated folic acid. The cyclization of glutamate produces proline, an amino acid important for synthesis of collagen and connective tissue. Our aim here is to review on some amino acids with high functional priority such as glutamine and to define their effective activity in human health and pathologies.

  1. Glutamic acid as anticancer agent: An overview.

    PubMed

    Dutta, Satyajit; Ray, Supratim; Nagarajan, K

    2013-10-01

    The objective of the article is to highlight various roles of glutamic acid like endogenic anticancer agent, conjugates to anticancer agents, and derivatives of glutamic acid as possible anticancer agents. Besides these emphases are given especially for two endogenous derivatives of glutamic acid such as glutamine and glutamate. Glutamine is a derivative of glutamic acid and is formed in the body from glutamic acid and ammonia in an energy requiring reaction catalyzed by glutamine synthase. It also possesses anticancer activity. So the transportation and metabolism of glutamine are also discussed for better understanding the role of glutamic acid. Glutamates are the carboxylate anions and salts of glutamic acid. Here the roles of various enzymes required for the metabolism of glutamates are also discussed.

  2. Synthesis and biological activities of d-chiro-inositol analogues with insulin-like actions.

    PubMed

    Rendle, P M; Kassibawi, F; Johnston, K A; Hart, J B; Cameron, S A; Falshaw, A; Painter, G F; Loomes, K M

    2016-10-21

    d-chiro-inositol (DCI, 1) evokes therapeutic actions in diabetes and insulin resistance but has sub-optimal pharmacokinetic profiles. To investigate what positions on the DCI cyclohexanol ring may be amenable to modification to improve pharmaceutical formulations, a series of analogues based on DCI were synthesised. These compounds were then evaluated for their ability to stimulate glucose transport using 3T3-L1 adipocytes as a model system. Positional analyses indicate that the hydroxyl group at position 1 is not essential for activity and can be modified without affecting glucose uptake. Removal of the hydroxyl at position 3 also had minimal effect on activity but this group is sensitive to modification. By comparison, the oxygen at position 2 is crucial to the potency of DCI, although this group can withstand modification without fundamentally affecting activity. These data reveal that positions 1 and 2 on the cyclohexanol ring of DCI offer further scope for modification to develop DCI analogues with desirable pharmacokinetic profiles for the potential treatment of metabolic disease. PMID:27410479

  3. Activation of beef-heart cytochrome c oxidase by cardiolipin and analogues of cardiolipin.

    PubMed

    Abramovitch, D A; Marsh, D; Powell, G L

    1990-10-24

    Beef-heart cytochrome c oxidase lacking endogenous lipids can be prepared by cholate-mediated exchange with dimyristoylphosphatidylcholine (Powell, G. L., Knowles, P. F. and Marsh, D. (1985) Biochim. Biophys. Acta 816, 191-194). These preparations retained practically no endogenous cardiolipin (less than 0.19 mol cardiolipin per mol of oxidase) but in Tween 80 they retained unaltered electron transport activity. Resupplementation of the dimyristoylphosphatidylcholine-substituted cytochrome oxidase with cardiolipin and cardiolipin analogues with different numbers of acyl chains or with a methylated headgroup enhanced the activity of the reconstituted enzyme to an extent dependent on the structure of the cardiolipin derivative. The Eadie-Hofstee plot showed biphasic kinetic behavior for all reconstituted preparations, even those completely lacking cardiolipin. This biphasic substrate dependence of the kinetics was simulated using the model of Brzezinski, P. and Malmström, B. G. (Proc. Natl. Acad. Sci. USA 83 (1986) 4282-4286), which implicates two interconverting enzyme conformations in the proton transport step. The activation of cytochrome c oxidase by the cardiolipin analogues could be explained in terms of an electrostatic enhancement of the surface concentrations of both cytochrome c and protons, and a facilitated interconversion between the two enzyme conformations.

  4. Synthesis of iminoalditol analogues of galactofuranosides and their activities against glycosidases.

    PubMed

    Sandbhor, Mahendra; Bhasin, Milan; Williams, Dean T; Hsieh, Margaret; Wu, Shih-Hsiung; Zou, Wei

    2008-11-24

    Iminoalditol analogues of galactofuranosides were synthesized from 1-C-(2'-oxo-propyl)-1,4-dideoxy-1,4-imino-d-galactosides and different amines by reductive amination, followed by removal of protecting groups. The activity of these compounds against galactosidases and other glycosidases was investigated. The best inhibitor against beta-galactosidase (bovine liver) is a diastereomeric mixture of an iminoalditol (10h), which contains a hydrophobic hexadecyl aglycon (R=C(16)H(33)), whereas no significant inhibitory activity was observed with compounds having a hydrophilic aglycon. Surprisingly, activation of alpha-galactosidase (coffee bean) by 10h was also observed. Because these results were obtained from a mixture of iminoalditols, the inhibition and activation of glycosidases could result from different diastereomers.

  5. Glycine activated ion channel subunits encoded by ctenophore glutamate receptor genes.

    PubMed

    Alberstein, Robert; Grey, Richard; Zimmet, Austin; Simmons, David K; Mayer, Mark L

    2015-11-01

    Recent genome projects for ctenophores have revealed the presence of numerous ionotropic glutamate receptors (iGluRs) in Mnemiopsis leidyi and Pleurobrachia bachei, among our earliest metazoan ancestors. Sequence alignments and phylogenetic analysis show that these form a distinct clade from the well-characterized AMPA, kainate, and NMDA iGluR subtypes found in vertebrates. Although annotated as glutamate and kainate receptors, crystal structures of the ML032222a and PbiGluR3 ligand-binding domains (LBDs) reveal endogenous glycine in the binding pocket, whereas ligand-binding assays show that glycine binds with nanomolar affinity; biochemical assays and structural analysis establish that glutamate is occluded from the binding cavity. Further analysis reveals ctenophore-specific features, such as an interdomain Arg-Glu salt bridge, present only in subunits that bind glycine, but also a conserved disulfide in loop 1 of the LBD that is found in all vertebrate NMDA but not AMPA or kainate receptors. We hypothesize that ctenophore iGluRs are related to an early ancestor of NMDA receptors, suggesting a common evolutionary path for ctenophores and bilaterian species, and suggest that future work should consider both glycine and glutamate as candidate neurotransmitters in ctenophore species. PMID:26460032

  6. Glycine activated ion channel subunits encoded by ctenophore glutamate receptor genes

    PubMed Central

    Alberstein, Robert; Grey, Richard; Zimmet, Austin; Simmons, David K.; Mayer, Mark L.

    2015-01-01

    Recent genome projects for ctenophores have revealed the presence of numerous ionotropic glutamate receptors (iGluRs) in Mnemiopsis leidyi and Pleurobrachia bachei, among our earliest metazoan ancestors. Sequence alignments and phylogenetic analysis show that these form a distinct clade from the well-characterized AMPA, kainate, and NMDA iGluR subtypes found in vertebrates. Although annotated as glutamate and kainate receptors, crystal structures of the ML032222a and PbiGluR3 ligand-binding domains (LBDs) reveal endogenous glycine in the binding pocket, whereas ligand-binding assays show that glycine binds with nanomolar affinity; biochemical assays and structural analysis establish that glutamate is occluded from the binding cavity. Further analysis reveals ctenophore-specific features, such as an interdomain Arg-Glu salt bridge, present only in subunits that bind glycine, but also a conserved disulfide in loop 1 of the LBD that is found in all vertebrate NMDA but not AMPA or kainate receptors. We hypothesize that ctenophore iGluRs are related to an early ancestor of NMDA receptors, suggesting a common evolutionary path for ctenophores and bilaterian species, and suggest that future work should consider both glycine and glutamate as candidate neurotransmitters in ctenophore species. PMID:26460032

  7. Bovine neuronal vesicular glutamate transporter activity is inhibited by ergovaline and other ergopeptines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    L-Glutamate (Glu) is the major excitatory neurotransmitter responsible for neurotransmission in the vertebrate central nervous system, including the gastrointestinal tract (GIT) of cattle. Vesicular Glu transporters VGLUT1 and VGLUT2 concentrate (50 mM) Glu (Km = 1 to 4 mM) into synaptic vesicles (S...

  8. Glycine activated ion channel subunits encoded by ctenophore glutamate receptor genes.

    PubMed

    Alberstein, Robert; Grey, Richard; Zimmet, Austin; Simmons, David K; Mayer, Mark L

    2015-11-01

    Recent genome projects for ctenophores have revealed the presence of numerous ionotropic glutamate receptors (iGluRs) in Mnemiopsis leidyi and Pleurobrachia bachei, among our earliest metazoan ancestors. Sequence alignments and phylogenetic analysis show that these form a distinct clade from the well-characterized AMPA, kainate, and NMDA iGluR subtypes found in vertebrates. Although annotated as glutamate and kainate receptors, crystal structures of the ML032222a and PbiGluR3 ligand-binding domains (LBDs) reveal endogenous glycine in the binding pocket, whereas ligand-binding assays show that glycine binds with nanomolar affinity; biochemical assays and structural analysis establish that glutamate is occluded from the binding cavity. Further analysis reveals ctenophore-specific features, such as an interdomain Arg-Glu salt bridge, present only in subunits that bind glycine, but also a conserved disulfide in loop 1 of the LBD that is found in all vertebrate NMDA but not AMPA or kainate receptors. We hypothesize that ctenophore iGluRs are related to an early ancestor of NMDA receptors, suggesting a common evolutionary path for ctenophores and bilaterian species, and suggest that future work should consider both glycine and glutamate as candidate neurotransmitters in ctenophore species.

  9. Enzymatic synthesis of γ-glutamylmethylamide from glutamic acid γ-methyl ester and methylamine catalyzed by Escherichia coli having γ-glutamyltranspeptidase activity.

    PubMed

    Xu, Lisheng; Gao, Guizhen; Wengen, Cao; Xu, Jigui; Zhao, Liang; Shi, Hongwei; Zhang, Xingtao

    2014-06-01

    A new method for the synthesis of γ-glutamylmethylamide is presented. Glutamic acid γ-methyl ester was used as substrate for γ-glutamylmethylamide synthesis catalyzed by Escherichia coli with γ-glutamyltranspeptidase activity. Reaction conditions were optimized by using 300 mM glutamic acid γ-methyl ester and 3,000 mM methylamine at pH 10 and 40 °C. Bioconversion rate of γ-glutamylmethylamide reached 87 % after 10 h. γ-Glutamyltranspeptidase was reversibly inhibited only when glutamic acid γ-methyl ester was above 300 mM.

  10. Parallel Synthesis and Biological Evaluation of 837 Analogues of Procaspase-Activating Compound 1 (PAC-1)

    PubMed Central

    Hsu, Danny C.; Roth, Howard S.; West, Diana C.; Botham, Rachel C.; Novotny, Chris J.; Schmid, Steven C.; Hergenrother, Paul J.

    2011-01-01

    Procaspase-Activating Compound 1 (PAC-1) is an ortho-hydroxy N-acyl hydrazone that enhances the enzymatic activity of procaspase-3 in vitro and induces apoptosis in cancer cells. An analogue of PAC-1, called S-PAC-1, was evaluated in a veterinary clinical trial in pet dogs with lymphoma and found to have considerable potential as an anticancer agent. With the goal of identifying more potent compounds in this promising class of experimental therapeutics, a combinatorial library based on PAC-1 was created, and the compounds were evaluated for their ability to induce death of cancer cells in culture. For library construction, 31 hydrazides were condensed in parallel with 27 aldehydes to create 837 PAC-1 analogues, with an average purity of 91%. The compounds were evaluated for their ability to induce apoptosis in cancer cells, and through this work, six compounds were discovered to be substantially more potent than PAC-1 and S-PAC-1. These six hits were further evaluated for their ability to relieve zinc-mediated inhibition of procaspase-3 in vitro. In general, the newly identified hit compounds are two- to four-fold more potent than PAC-1 and S-PAC-1 in cell culture, and thus have promise as experimental therapeutics for treatment of the many cancers that have elevated expression levels of procaspase-3. PMID:22007686

  11. Burst firing in gonadotrophin-releasing hormone neurones does not require ionotrophic GABA or glutamate receptor activation.

    PubMed

    Lee, K; Liu, X; Herbison, A E

    2012-12-01

    Burst firing is a feature of many neuroendocrine cell types, including the hypothalamic gonadotrophin-releasing hormone (GnRH) neurones that control fertility. The role of intrinsic and extrinsic influences in generating GnRH neurone burst firing is presently unclear. In the present study, we investigated the role of fast amino acid transmission in burst firing by examining the effects of receptor antagonists on bursting displayed by green fluorescent protein GnRH neurones in sagittal brain slices prepared from adult male mice. Blockade of AMPA and NMDA glutamate receptors with a cocktail of CNQX and AP5 was found to have no effects on burst firing in GnRH neurones. The frequency of bursts, dynamics of individual bursts, or percentage of firing clustered in bursts was not altered. Similarly, GABA(A) receptor antagonists bicuculline and picrotoxin had no effects upon burst firing in GnRH neurones. To examine the importance of both glutamate and GABA ionotrophic signalling, a cocktail including picrotoxin, CNQX and AP5 was used but, again, this was found to have no effects on GnRH neurone burst firing. To further question the impact of endogenous amino acid release on burst firing, electrical activation of anteroventral periventricular nuclei GABA/glutamate inputs to GnRH neurones was undertaken and found to have no impact on burst firing. Taken together, these observations indicate that bursting in GnRH neurones is not dependent upon acute ionotrophic GABA and glutamate signalling and suggest that extrinsic inputs to GnRH neurones acting through AMPA, NMDA and GABA(A) receptors are unlikely to be required for burst initiation in these cells.

  12. Medial Septal NMDA Glutamate Receptors are Involved in Modulation of Blood Natural Killer Cell Activity in Rats.

    PubMed

    Podlacha, Magdalena; Glac, Wojciech; Listowska, Magdalena; Grembecka, Beata; Majkutewicz, Irena; Myślińska, Dorota; Plucińska, Karolina; Jerzemowska, Grażyna; Grzybowska, Maria; Wrona, Danuta

    2016-03-01

    The purpose of the present study was to determine the specific role of the medial septal (MS) NMDA glutamate receptors on peripheral blood natural killer cell cytotoxicity (NKCC) and their (large granular lymphocyte, LGL) number, as well as the plasma concentration of tumor necrosis factor α (TNF-α) and corticosterone in male Wistar rats exposed to elevated plus maze (EPM) stress or non-stress conditions. The NMDA groups were injected with NMDA glutamate receptor agonist (N-methyl-D-aspartate; 0.25 μg/rat), the D-AP7 group was injected with DL-2-amino-7-phosphoheptanoate (0.1 μg/rat), an antagonist of NMDA glutamate receptors, and the control Sal group with saline (0.5 μl/rat) via previously implanted cannulae into the MS. There was an increase in the NKCC, NK/LGL number and plasma TNF-α concentration after the NMDA injections, being much stronger within the rats under non-stress conditions rather than the rats exposed to EPM stress. These parameters were decreased in the D-AP7 rats, suggesting receptor/ion channel specificity. Moreover, a lower plasma corticosterone concentration within the NMDA rather than the Sal and D-AP7 groups was found. The obtained results suggest that activation of the NMDA glutamate receptors in the MS, accompanied by changes in the corticosterone and cytokine responses, may be involved in modulation of the blood natural anti-tumor response, under EPM stress and non-stress conditions. PMID:26454750

  13. Insecticidal and Enzyme Inhibitory Activities of Sparassol and Its Analogues against Drosophila suzukii.

    PubMed

    Kim, Junheon; Jang, Miyeon; Lee, Kyoung-Tae; Yoon, Kyungjae Andrew; Park, Chung Gyoo

    2016-07-13

    Drosophila suzukii is an economically important pest in America and Europe as well as in Asia. Sparassol and methyl orsellinate are naturally produced by the cultivating mushrooms Sparassis cripta and Sparassis latifolia. Fumigant and contact toxicities of synthetic sparassol and its analogues, methyl orsellinate and methyl 2,4-dimethoxy-6-methylbenzoate (DMB), were investigated. Negligible fumigant activity was observed from the tested compounds. However, DMB showed the strongest contact toxicity, followed by sparassol and methyl orsellinate. The possible modes of action of the compounds were assessed for their acetylcholinesterase (AChE)- and glutathione S-transferase (GST)-inhibiting activities. AChE activity was weakly inhibited by methyl orsellinate and DMB, but GST was inhibited by sparassol, methyl orsellinate, and DMB. Thus, DMB could be a promising alternative to common insecticides as it can be easily synthesized from sparassol, which is the natural product of Sparassis species. Sparassis species could be an industrial resource of DMB. PMID:27327201

  14. Synthesis and anti-cancer activity of C-ring-functionalized prodigiosin analogues.

    PubMed

    Regourd, Jasmine; Ali, Adeeb Al-Sheikh; Thompson, Alison

    2007-04-01

    Prodigiosin is the parent member of the 4-methoxypyrrolyldipyrromethene family of natural products and is known for its anti-cancer activity. A new series of analogues was synthesized, incorporating pendent functional esters and beta-carbonyl substituents on the C-ring. The beta-carbonyl group allowed for the facile isolation of the prodigiosenes, and the pendent esters allow for further derivatization. The novel prodigiosenes generally retain the anti-cancer activity of prodigiosin in 60 human cell lines derived from nine cancer cell types, with neither the conjugated beta-carbonyl group, as either ketone or ester, nor the pendent ester significantly reducing the anti-cancer activity of the core skeleton.

  15. Activation of synaptic group II metabotropic glutamate receptors induces long-term depression at GABAergic synapses in CNS neurons.

    PubMed

    Tang, Zheng-Quan; Liu, Yu-Wei; Shi, Wei; Dinh, Emilie Hoang; Hamlet, William R; Curry, Rebecca J; Lu, Yong

    2013-10-01

    Metabotropic glutamate receptor (mGluR)-dependent homosynaptic long-term depression (LTD) has been studied extensively at glutamatergic synapses in the CNS. However, much less is known about heterosynaptic long-term plasticity induced by mGluRs at inhibitory synapses. Here we report that pharmacological or synaptic activation of group II mGluRs (mGluR II) induces LTD at GABAergic synapses without affecting the excitatory glutamatergic transmission in neurons of the chicken cochlear nucleus. Coefficient of variation and failure rate analysis suggested that the LTD was expressed presynaptically. The LTD requires presynaptic spike activity, but does not require the activation of NMDA receptors. The classic cAMP-dependent protein kinase A signaling is involved in the transduction pathway. Remarkably, blocking mGluR II increased spontaneous GABA release, indicating the presence of tonic activation of mGluR II by ambient glutamate. Furthermore, synaptically released glutamate induced by electrical stimulations that concurrently activated both the glutamatergic and GABAergic pathways resulted in significant and constant suppression of GABA release at various stimulus frequencies (3.3, 100, and 300 Hz). Strikingly, low-frequency stimulation (1 Hz, 15 min) of the glutamatergic synapses induced heterosynaptic LTD of GABAergic transmission, and the LTD was blocked by mGluR II antagonist, indicating that synaptic activation of mGluR II induced the LTD. This novel form of long-term plasticity in the avian auditory brainstem may play a role in the development as well as in temporal processing in the sound localization circuit.

  16. Antifungal activity of eugenol analogues. Influence of different substituents and studies on mechanism of action.

    PubMed

    Carrasco, Héctor; Raimondi, Marcela; Svetaz, Laura; Di Liberto, Melina; Rodriguez, María V; Espinoza, Luis; Madrid, Alejandro; Zacchino, Susana

    2012-01-19

    Twenty one phenylpropanoids (including eugenol and safrole) and synthetic analogues, thirteen of them new compounds, were evaluated for antifungal properties, first with non-targeted assays against a panel of human opportunistic pathogenic fungi. Some structure-activity relationships could be observed, mainly related to the influence of an allyl substituent at C-4, an OH group at C-1 and an OCH(3) at C-2 or the presence of one or two NO(2) groups in different positions of the benzene ring. All active compounds were tested in a second panel of clinical isolates of C. albicans and non-albicans Candida spp., Cryptococcus neoformans and dermatophytes. The eugenol derivative 4-allyl-2-methoxy-5-nitrophenol (2) was the most active structure against all strains tested, and therefore it was submitted to targeted assays. These studies showed that the antifungal activity of 2 was not reversed in the presence of an osmotic support such as sorbitol, suggesting that it does not act by inhibiting the fungal cell wall synthesis or assembly. On the other hand, the Ergosterol Assay showed that 2 did not bind to the main sterol of the fungal membrane up to 250 µg mL-1. In contrast, a 22% of fungal membrane damage was observed at concentrations = 1 × MIC and 71% at 4× MIC, when 2 was tested in the Cellular Leakage assay. The comparison of log P and MICs for all compounds revealed that the antifungal activity of the eugenol analogues would not to be related to lipophilicity.

  17. Role of the phenolic hydroxyl group in the biological activities of simplified analogue of aplysiatoxin with antiproliferative activity.

    PubMed

    Yanagita, Ryo C; Kamachi, Hiroaki; Tanaka, Keisuke; Murakami, Akira; Nakagawa, Yu; Tokuda, Harukuni; Nagai, Hiroshi; Irie, Kazuhiro

    2010-10-15

    The 18-deoxy derivative (3) of a simplified analogue (1) of aplysiatoxin with antiproliferative activity was synthesized to examine the role of the phenolic hydroxyl group at position 18 in the biological activities of 1. Compound 3 as well as 1 showed significant affinity for protein kinase Cδ (PKCδ), and the antiproliferative activity of 3 was slightly higher than that of 1. However, the anti-tumor-promoting activity of 3 was less than that of 1 in vitro, suggesting that the phenolic hydroxyl group of 1 is necessary for the anti-tumor-promoting activity but not for the binding of PKCδ and antiproliferative activity. Moreover, PKC isozyme selectivity of 3 was similar to that of 1, suggesting non-PKC receptors for these compounds to play some roles in the anti-tumor-promoting activity of 1.

  18. Cholecystokinin receptors: disparity between phosphoinositide breakdown and amylase releasing activity of CCK analogues in pancreas

    SciTech Connect

    Lin, C.W.; Grant, D.; Bianchi, B.; Miller, T.; Witte, D.; Shue, Y.K.; Nadzan, A.

    1986-03-05

    Cholecystokinin (CCK) peptides are a family of hormones which also occur in brain. In pancreas CCK stimulates the release of amylase, a process that is dependent on the mobilization of intracellular Ca/sup 2 +/. Recent evidence suggests that inositol 1,4,5-trisphosphate, the breakdown product of phosphatidylinositol 4,5-bisphosphate, is responsible for the rise in intracellular Ca/sup 2 +/. Their laboratory has developed assays to study synthetic CCK analogues using radioligand binding, PI breakdown and amylase release. They have shown that there are good correlations among these three assay systems for the carboxy terminal fragments of CCK/sub 8/. Recently, they have discovered synthetic analogues of CCK/sub 4/ that are full agonists in amylase release but are ineffective in causing PI breakdown. In particular, A-61576, Boc-5-amino-2-indolemethylene-pent-2-ene-1-oyl-Leu-Asp-Phe-NH/sub 2/, is a full agonist in the amylase releasing assay, but is devoid of PI stimulating activity. A-61576 completely reverses the stimulation of PI response induced by CCK/sub 8/, indicative of an antagonist. Since a mechanism other than the PI breakdown is responsible for amylase release by A-61576, they suggest that separate receptors are responsible for PI breakdown and amylase release.

  19. Sulforaphane Analogues with Heterocyclic Moieties: Syntheses and Inhibitory Activities against Cancer Cell Lines.

    PubMed

    Shi, Ye-Hui; Dai, Dong-Fang; Li, Jing; Dong, Yan-Wei; Jiang, Yin; Li, Huan-Gong; Gao, Yuan; Chong, Chuan-Ke; Li, Hui-Ying; Chu, Xiao-Qian; Yang, Cheng; Zhang, Quan; Tong, Zhong-Sheng; Bai, Cui-Gai; Chen, Yue

    2016-01-01

    Recent studies have shown that sulforaphane (SFN) selectively inhibits the growth of ALDH⁺ breast cancer stem-like cells.Herein, a series of SFN analogues were synthesized and evaluated against breast cancer cell lines MCF-7 and SUM-159, and the leukemia stem cell-like cell line KG-1a. These SFN analogues were characterized by the replacement of the methyl group with heterocyclic moieties, and the replacement of the sulfoxide group with sulfide or sulfone. A growth inhibitory assay indicated that the tetrazole analogs 3d, 8d and 9d were significantly more potent than SFN against the three cancer cell lines. Compound 14c, the water soluble derivative of tetrazole sulfide 3d, demonstrated higher potency against KG-1a cell line than 3d. SFN, 3d and 14c significantly induced the activation of caspase-3, and reduced the ALDH⁺ subpopulation in the SUM159 cell line, while the marketed drug doxrubicin(DOX) increased the ALDH⁺ subpopulation. PMID:27110751

  20. Design and Synthesis of Norendoxifen Analogues with Dual Aromatase Inhibitory and Estrogen Receptor Modulatory Activities

    PubMed Central

    Lv, Wei; Liu, Jinzhong; Skaar, Todd C.; Flockhart, David A.; Cushman, Mark

    2015-01-01

    Both selective estrogen receptor modulators and aromatase inhibitors are widely used for the treatment of breast cancer. Compounds with both aromatase inhibitory and estrogen receptor modulatory activities could have special advantages for treatment of breast cancer. Our previous efforts led to the discovery of norendoxifen as the first compound with dual aromatase inhibitory and estrogen receptor binding activities. To optimize its efficacy and aromatase selectivity versus other cytochrome P450 enzymes, a series of structurally related norendoxifen analogues were designed and synthesized. The most potent compound, 4'-hydroxynorendoxifen (10), displayed elevated inhibitory potency against aromatase and enhanced affinity for estrogen receptors when compared to norendoxifen. The selectivity of 10 for aromatase versus other cytochrome P450 enzymes was also superior to norendoxifen. 4'-Hydroxynorendoxifen is therefore an interesting lead for further development to obtain new anticancer agents of potential value for the treatment of breast cancer. PMID:25751283

  1. Synthesis and evaluation of antioxidant activity of new quinoline-2-carbaldehyde hydrazone derivatives: bioisosteric melatonin analogues.

    PubMed

    Puskullu, M Orhan; Shirinzadeh, Hanif; Nenni, Merve; Gurer-Orhan, Hande; Suzen, Sibel

    2016-01-01

    Overproduction of reactive oxygen species results in oxidative stress that can cause fatal damage to vital cell structures. It is known that the use of antioxidants could be beneficial in the prevention or delay of numerous diseases associated with oxidative stress. Melatonin (MLT) is known as a powerful free-radical scavenger and antioxidant. It was found that indole ring of MLT can be employed by bioisosteric replacement by other aromatic rings. Quinoline derivatives constitute an important class of compounds for new drug development. Owing to quinoline and hydrazones appealing physiological properties and are mostly found in numerous biologically active compounds a series of quinoline-2-carbaldehyde hydrazone derivatives were synthesized as bioisosteric analogues of MLT, characterized and in vitro antioxidant activity was investigated by evaluating their reducing effect against oxidation of a redox-sensitive fluorescent probe. Cytotoxicity potential of all compounds was investigated both by lactate dehydrogenase leakage assay and by MTT assay.

  2. The cannabinoid CB1 receptor biphasically modulates motor activity and regulates dopamine and glutamate release region dependently.

    PubMed

    Polissidis, Alexia; Galanopoulos, Andreas; Naxakis, George; Papahatjis, Demetris; Papadopoulou-Daifoti, Zeta; Antoniou, Katerina

    2013-03-01

    Cannabinoid administration modulates both dopaminergic and glutamatergic neurotransmission. The present study examines the effects of high and low dose WIN55,212-2, a CB1 receptor agonist, on extracellular dopamine and glutamate release in vivo via brain microdialysis in the nucleus accumbens (NAc), striatum and prefrontal cortex (PFC) in parallel to its effects on locomotor activity. WIN55,212-2 increased extracellular dopamine in the NAc (1 mg/kg i.p.), striatum (0.1 and 1 mg/kg i.p.) and PFC (1 mg/kg i.p.). Glutamate release was also elevated by WIN55,212-2 in the PFC (1 mg/kg i.p.) whereas in the NAc (0.1 and 1 mg/kg i.p.) and striatum, it was reduced (1 mg/kg i.p.). WIN55,212-2 administration produced hyperlocomotion at the lower dose (0.1 mg/kg i.p.) and hypolocomotion at the higher dose (1 mg/kg i.p.). Co-administration with the CB1 antagonist, SR-141716A (0.03 mg/kg i.p.), prevented the above effects. According to the present results, WIN55,212-2 affected locomotor activity biphasically while exerting converging effects on dopamine activity but diverging effects on glutamate release between cortical and subcortical regions, especially at the higher dose. These findings emphasize the involvement of the CB1 receptor in the simultaneous modulation of dopaminergic and glutamatergic neurotransmission in brain regions involved in reward and locomotion and suggest possible underlying mechanisms of acute cannabinoid exposure and its psychoactive and behavioural manifestations.

  3. Lysine and Arginine Reduce the Effects of Cerebral Ischemic Insults and Inhibit Glutamate-Induced Neuronal Activity in Rats

    PubMed Central

    Kondoh, Takashi; Kameishi, Makiko; Mallick, Hruda Nanda; Ono, Taketoshi; Torii, Kunio

    2010-01-01

    Intravenous administration of arginine was shown to be protective against cerebral ischemic insults via nitric oxide production and possibly via additional mechanisms. The present study aimed at evaluating the neuroprotective effects of oral administration of lysine (a basic amino acid), arginine, and their combination on ischemic insults (cerebral edema and infarction) and hemispheric brain swelling induced by transient middle cerebral artery occlusion/reperfusion in rats. Magnetic resonance imaging and 2,3,5-triphenyltetrazolium chloride staining were performed 2 days after ischemia induction. In control animals, the major edematous areas were observed in the cerebral cortex and striatum. The volumes associated with cortical edema were significantly reduced by lysine (2.0 g/kg), arginine (0.6 g/kg), or their combined administration (0.6 g/kg each). Protective effects of these amino acids on infarction were comparable to the inhibitory effects on edema formation. Interestingly, these amino acids, even at low dose (0.6 g/kg), were effective to reduce hemispheric brain swelling. Additionally, the effects of in vivo microiontophoretic (juxtaneuronal) applications of these amino acids on glutamate-evoked neuronal activity in the ventromedial hypothalamus were investigated in awake rats. Glutamate-induced neuronal activity was robustly inhibited by microiontophoretic applications of lysine or arginine onto neuronal membranes. Taken together, our results demonstrate the neuroprotective effects of oral ingestion of lysine and arginine against ischemic insults (cerebral edema and infarction), especially in the cerebral cortex, and suggest that suppression of glutamate-induced neuronal activity might be the primary mechanism associated with these neuroprotective effects. PMID:20589237

  4. Inhibition of the intrinsic NAD+ glycohydrolase activity of CD38 by carbocyclic NAD analogues.

    PubMed Central

    Wall, K A; Klis, M; Kornet, J; Coyle, D; Amé, J C; Jacobson, M K; Slama, J T

    1998-01-01

    Carba-NAD and pseudocarba-NAD are carbocyclic analogues of NAD+ in which a 2,3-dihydroxycyclopentane methanol replaces the beta-d-ribonucleotide ring of the nicotinamide riboside moiety of NAD+ [Slama and Simmons (1988) Biochemistry 27, 183-193]. These carbocyclic NAD+ analogues, related to each other as diastereomers, have been tested as inhibitors of the intrinsic NAD+ glycohydrolase activity of human CD38, dog spleen NAD+ glycohydrolase, mouse CD38 and Aplysia californica cADP-ribose synthetase. Pseudocarba-NAD, the carbocyclic dinucleotide in which l-2,3-dihydroxycyclopentane methanol replaces the d-ribose of the nicotinamide riboside moiety of NAD+, was found to be the more potent inhibitor. Pseudocarba-NAD was shown to inhibit the intrinsic NAD+ glycohydrolase activity of human CD38 competitively, with Ki=148 microM determined for the recombinant extracellular protein domain and Ki=180 microM determined for the native protein expressed as a cell-surface enzyme on cultured Jurkat cells. Pseudocarba-NAD was shown to be a non-competitive inhibitor of the purified dog spleen NAD+ glycohydrolase, with Kis=47 miroM and Kii=198 microM. Neither pseudocarba-NAD nor carba-NAD inhibited mouse CD38 or Aplysia californica cADP-ribose synthetase significantly at concentrations up to 1 mM. The results underscore significant species differences in the sensitivity of these enzymes to inhibition, and indicate that pseudocarba-NAD will be useful as an inhibitor of the enzymic activity of human but not mouse CD38 in studies using cultured cells. PMID:9794804

  5. Novel curcumin analogue 14p protects against myocardial ischemia reperfusion injury through Nrf2-activating anti-oxidative activity

    SciTech Connect

    Li, Weixin; Wu, Mingchai; Tang, Longguang; Pan, Yong; Liu, Zhiguo; Zeng, Chunlai; Wang, Jingying; Wei, Tiemin; Liang, Guang

    2015-01-15

    Background: Alleviating the oxidant stress associated with myocardial ischemia reperfusion has been demonstrated as a potential therapeutic approach to limit ischemia reperfusion (I/R)-induced cardiac damage. Curcumin, a natural compound with anti-oxidative activity, exerts beneficial effect against cardiac I/R injury, but poor chemical and metabolic stability. Previously, we have designed and synthesized a series of mono-carbonyl analogues of curcumin (MACs) with high stability. This study aims to find new anti-oxidant MACs and to demonstrate their effects and mechanisms against I/R-induced heart injury. Methods: H9c2 cells challenged with H{sub 2}O{sub 2} or TBHP were used for in vitro bio-screening and mechanistic studies. The MDA, H{sub 2}O{sub 2} and SOD levels in H9C2 cells were determined, and the cell viability was assessed by MTT assay. Myocardial I/R mouse models administrated with or without the compound were used for in vivo studies. Results: The in vitro cell-based screening showed that curcumin analogues 8d and 14p exhibited strong anti-oxidative effects. Pre-treatment of H9c2 cells with 14p activated Nrf2 signaling pathway, attenuated H{sub 2}O{sub 2}-increased MDA and SOD level, followed by the inhibition of TBHP-induced cell death and Bax/Bcl-2–caspase-3 pathway activation. Silencing Nrf2 significantly reversed the protective effects of 14p. In in vivo animal model of myocardial I/R, administration of low dose 14p (10 mg/kg) reduced infarct size and myocardial apoptosis to the same extent as the high dose curcumin (100 mg/kg). Conclusion: These data support the novel curcumin analogue 14p as a promising antioxidant to decrease oxidative stress and limit myocardial ischemia reperfusion injury via activating Nrf2. - Highlights: • Mono-carbonyl analogue of curcumin, 14p, exhibited better chemical stability. • Compound 14p inhibited TBHP-induced apoptosis through activating Nrf2 in vitro. • Compound 14p limited myocardial ischemia

  6. Synthesis of 8-Oxa analogues of norcocaine endowed with interesting cocaine-like activity.

    PubMed

    Kozikowski, A P; Simoni, D; Roberti, M; Rondanin, R; Wang, S; Du, P; Johnson, K M

    1999-07-01

    In order to further explore the importance of cocaine's bridge nitrogen atom in binding to the dopamine transporter (DAT), we have synthesized the previously known racemic 8-oxa-norcocaines 3-6 in which the nitrogen atom has been replaced by oxygen. Additionally, to avoid incorrect interpretations of biological data that may stem from the use of racemic materials, several of these analogues were synthesized and tested in non-racemic form. (-)-8-Oxa-norcocaine (3) was found to bind to the cocaine recognition site and to inhibit the dopamine transporter with potencies only about 8-fold and 4-fold, respectively, less than those of norcocaine (2). (-)-8-Oxa-pseudonorcocaine (4) as well as (+)-8-oxa-norcocaine (3) were found to be comparable in activity to (-)-oxa-norcocaine. These pharmacological findings support our earlier suggestion that cocaine is likely to bind in its neutral form to the DAT.

  7. Structure-based design, synthesis and preliminary anti-inflammatory activity of bolinaquinone analogues.

    PubMed

    Petronzi, Carmen; Filosa, Rosanna; Peduto, Antonella; Monti, Maria Chiara; Margarucci, Luigi; Massa, Antonio; Ercolino, Simona Francesca; Bizzarro, Valentina; Parente, Luca; Riccio, Raffaele; de Caprariis, Paolo

    2011-02-01

    As a part of our drug discovery efforts we developed a series of simplified derivatives of bolinaquinone (BLQ), a hydroxyquinone marine metabolite, showing potent anti-inflammatory activity. Thirteen new hydroxyquinone derivatives closely related to BLQ were synthesized and tested on mouse macrophage-like RAW 264.7 cell line in order to investigate their ability to modulate the production of Prostaglandin E2 (PGE2). This optimization process led to the identification of three strictly correlated compounds with comparable and higher inhibitory potency than BLQ on PGE2 production. To evaluate the affinity of BLQ and its analogues for hsPLA2, surface plasmon resonance (SPR) experiments were performed. PMID:21163556

  8. Total Synthesis and Antifungal Activity of Palmarumycin CP17 and Its Methoxy Analogues.

    PubMed

    Wang, Ruina; Liu, Guoyue; Yang, Mingyan; Wang, Mingan; Zhou, Ligang

    2016-01-01

    Total synthesis of naturally occurring spirobisnaphthalene palmarumycin CP17 and its methoxy analogues was first achieved through Friedel-Crafts acylation, Wolff-Kishner reduction, intramolecular cyclization, ketalization, benzylic oxidation, and demethylation using the inexpensive and readily available methoxybenzene, 1,2-dimethoxybenzene and 1,4-dimethoxybenzene and 1,8-dihydroxynaphthalene as raw materials. Demethylation with (CH₃)₃SiI at ambient temperature resulted in ring A aromatization and acetal cleavage to give rise to binaphthyl ethers. The antifungal activities of these spirobisnaphthalene derivatives were evaluated, and the results revealed that 5 and 9b exhibit EC50 values of 9.34 µg/mL and 12.35 µg/mL, respectively, against P. piricola. PMID:27164077

  9. Phosphonic analogues of tyrosine and 3,4-dihydroxyphenylalanine (dopa) influence mushroom tyrosinase activity.

    PubMed

    Lejczak, B; Kafarski, P; Makowiecka, E

    1987-02-15

    A series of phosphonic analogues of tyrosine and 3,4-dihydroxyphenylalanine (dopa) were synthesized in order to study their interaction with mushroom tyrosinase. 1-Amino-2-(3,4-dihydroxyphenyl)ethylphosphonic acid and 1-amino-2-(3,4-dimethoxyphenyl)ethylphosphonic acid turned out to be substrates for mushroom tyrosinase with Km values of 3.3 mM and 9.3 mM respectively. Shortening of the alkyl chain by one methylene group gave amino-(3,4-dihydroxyphenyl)methylphosphonic acid, one of the most powerful known inhibitors of this enzyme. This compound, racemic as well as in its optically active forms, exerts a mixed type of inhibition with an affinity for the enzyme one order of magnitude greater than that of the natural substrate. PMID:3109385

  10. Phosphonic analogues of tyrosine and 3,4-dihydroxyphenylalanine (dopa) influence mushroom tyrosinase activity.

    PubMed Central

    Lejczak, B; Kafarski, P; Makowiecka, E

    1987-01-01

    A series of phosphonic analogues of tyrosine and 3,4-dihydroxyphenylalanine (dopa) were synthesized in order to study their interaction with mushroom tyrosinase. 1-Amino-2-(3,4-dihydroxyphenyl)ethylphosphonic acid and 1-amino-2-(3,4-dimethoxyphenyl)ethylphosphonic acid turned out to be substrates for mushroom tyrosinase with Km values of 3.3 mM and 9.3 mM respectively. Shortening of the alkyl chain by one methylene group gave amino-(3,4-dihydroxyphenyl)methylphosphonic acid, one of the most powerful known inhibitors of this enzyme. This compound, racemic as well as in its optically active forms, exerts a mixed type of inhibition with an affinity for the enzyme one order of magnitude greater than that of the natural substrate. PMID:3109385

  11. SAR-Based Optimization of a 4-Quinoline Carboxylic Acid Analogue with Potent Antiviral Activity

    PubMed Central

    2013-01-01

    It is established that drugs targeting viral proteins are at risk of generating resistant strains. However, drugs targeting host factors can potentially avoid this problem. Herein, we report structure–activity relationship studies leading to the discovery of a very potent lead compound 6-fluoro-2-(5-isopropyl-2-methyl-4-phenoxyphenyl)quinoline-4-carboxylic acid (C44) that inhibits human dihydroorotate dehydrogenase (DHODH) with an IC50 of 1 nM and viral replication of VSV and WSN-Influenza with an EC50 of 2 nM and 41 nM. We also solved the X-ray structure of human DHODH bound to C44, providing structural insight into the potent inhibition of biaryl ether analogues of brequinar. PMID:23930152

  12. Mechanism of muscarinic receptor-induced K+ channel activation as revealed by hydrolysis-resistant GTP analogues

    PubMed Central

    1988-01-01

    The role of a guanine nucleotide-binding protein (Gk) in the coupling between muscarinic receptor activation and opening of an inwardly rectifying K+ channel [IK(M)] was examined in cardiac atrial myocytes, using hydrolysis-resistant GTP analogues. In the absence of muscarinic agonist, GTP analogues produced a membrane current characteristic of IK(M). The initial rate of appearance of this receptor-independent IK(M) was measured for the various analogues in order to explore the kinetic properties of IK(M) activation. We found that IK(M) activation is controlled solely by the intracellular analogue/GTP ratio and not by the absolute concentrations of the nucleotides. Analogues competed with GTP for binding to Gk with the following relative affinities: GTP gamma S greater than GTP greater than GppNHp greater than GppCH2p. At sufficiently high intracellular concentrations, however, all GTP analogues produced the same rate of IK(M) activation. This analogue- independent limiting rate is likely to correspond to the rate of GDP release from inactive, GDP-bound Gk. Muscarinic receptor stimulation by nanomolar concentrations of acetylcholine (ACh), which do not elicit IK(M) under control conditions, catalyzed IK(M) activation in the presence of GTP analogues. The rate of Gk activation by ACh (kACh) was found to be described by the simple relationship kACh = 8.4 X 10(8) min- 1 M-1.[ACh] + 0.44 min-1, the first term of which presumably reflects the agonist-catalyzed rate of GDP release from the Gk.GDP complex, while the second term corresponds to the basal rate of receptor- independent GDP release. Combined with the estimated K0.5 of the IK(M)- [ACh] dose-effect relationship, 160 nM, this result also allowed us to estimate the rate of Gk.GTP hydrolysis, kcat, to be near 135 min-1. These results provide, for the first time, a quantitative description of the salient features of G-protein function in vivo. PMID:2455765

  13. Identification by mutagenesis of a conserved glutamate (Glu487) residue important for catalytic activity in rat liver carnitine palmitoyltransferase II.

    PubMed

    Zheng, Guolu; Dai, Jia; Woldegiorgis, Gebre

    2002-11-01

    Mammalian mitochondrial membranes express two active but distinct carnitine palmitoyltransferases: carnitine palmitoyltransferase I (CPTI), which is malonyl coA-sensitive and detergent-labile; and carnitine palmitoyltransferase II (CPTII), which is malonyl coA-insensitive and detergent-stable. To determine the role of the highly conserved C-terminal acidic residues glutamate 487 (Glu(487)) and glutamate 500 (Glu(500)) on catalytic activity in rat liver CPTII, we separately mutated these residues to alanine, aspartate, or lysine, and the effect of the mutations on CPTII activity was determined in the Escherichia coli-expressed mutants. Substitution of Glu(487) with alanine, aspartate, or lysine resulted in almost complete loss in CPTII activity. Because a conservative substitution mutation of this residue, Glu(487) with aspartate (E487D), resulted in a 97% loss in activity, we predicted that Glu(487) would be at the active-site pocket of CPTII. The substantial loss in CPTII activity observed with the E487K mutant, along with the previously reported loss in activity observed in a child with a CPTII deficiency disease, establishes that Glu(487) is crucial for maintaining the configuration of the liver isoform of the CPTII active site. Substitution of the conserved Glu(500) in CPTII with alanine or aspartate reduced the V(max) for both substrates, suggesting that Glu(500) may be important in stabilization of the enzyme-substrate complex. A conservative substitution of Glu(500) to aspartate resulted in a significant decrease in the V(max) for the substrates. Thus, Glu(500) may play a role in substrate binding and catalysis. Our site-directed mutagenesis studies demonstrate that Glu(487) in the liver isoform of CPTII is essential for catalysis. PMID:12200419

  14. Catalytic irreversible inhibition of bacterial and plant arginine decarboxylase activities by novel substrate and product analogues.

    PubMed

    Bitonti, A J; Casara, P J; McCann, P P; Bey, P

    1987-02-15

    Arginine decarboxylase (ADC) activity from Escherichia coli and two plant species (oats and barley) was inhibited by five new substrate (arginine) and product (agmatine) analogues. The five compounds, (E)-alpha-monofluoromethyldehydroarginine (delta-MFMA), alpha-monofluoromethylarginine (MFMA), alpha-monofluoromethylagatine (FMA), alpha-ethynylagmatine (EA) and alpha-allenylagmatine (AA), were all more potent inhibitors of ADC activity than was alpha-difluoromethylarginine (DFMA), the only irreversible inhibitor of this enzyme described previously. The inhibition caused by the five compounds was apparently enzyme-activated and irreversible, since the loss of enzyme activity followed pseudo-first-order kinetics, was time-dependent, the natural substrate of ADC (arginine) blocked the effects of the inhibitors, and the inhibition remained after chromatography of inhibited ADC on Sephadex G-25 or on overnight dialysis of the enzyme. DFMA, FMA, delta-MFMA and MFMA were effective at very low concentrations (10 nM-10 microM) at inhibiting ADC activity in growing E. coli. FMA was also shown to deplete putrescine effectively in E. coli, particularly when combined with an inhibitor of ornithine decarboxylase, alpha-monofluoromethyl-putrescine. The potential uses of the compounds for the study of the role of polyamine biosynthesis in bacteria and plants is discussed.

  15. Catalytic irreversible inhibition of bacterial and plant arginine decarboxylase activities by novel substrate and product analogues.

    PubMed Central

    Bitonti, A J; Casara, P J; McCann, P P; Bey, P

    1987-01-01

    Arginine decarboxylase (ADC) activity from Escherichia coli and two plant species (oats and barley) was inhibited by five new substrate (arginine) and product (agmatine) analogues. The five compounds, (E)-alpha-monofluoromethyldehydroarginine (delta-MFMA), alpha-monofluoromethylarginine (MFMA), alpha-monofluoromethylagatine (FMA), alpha-ethynylagmatine (EA) and alpha-allenylagmatine (AA), were all more potent inhibitors of ADC activity than was alpha-difluoromethylarginine (DFMA), the only irreversible inhibitor of this enzyme described previously. The inhibition caused by the five compounds was apparently enzyme-activated and irreversible, since the loss of enzyme activity followed pseudo-first-order kinetics, was time-dependent, the natural substrate of ADC (arginine) blocked the effects of the inhibitors, and the inhibition remained after chromatography of inhibited ADC on Sephadex G-25 or on overnight dialysis of the enzyme. DFMA, FMA, delta-MFMA and MFMA were effective at very low concentrations (10 nM-10 microM) at inhibiting ADC activity in growing E. coli. FMA was also shown to deplete putrescine effectively in E. coli, particularly when combined with an inhibitor of ornithine decarboxylase, alpha-monofluoromethyl-putrescine. The potential uses of the compounds for the study of the role of polyamine biosynthesis in bacteria and plants is discussed. PMID:3297044

  16. Novel (E)-β-Farnesene Analogues Containing 2-Nitroiminohexahydro-1,3,5-triazine: Synthesis and Biological Activity Evaluation.

    PubMed

    Qin, Yaoguo; Zhang, Jingpeng; Song, Dunlun; Duan, Hongxia; Li, Wenhao; Yang, Xinling

    2016-01-01

    In order to discover novel eco-friendly compounds with good activity for aphid control, (E)-β-farnesene (EβF), the main component of the aphid alarm pheromone, was chosen as the lead compound. By introducing a 2-nitroimino-hexahydro-1,3,5-triazine moiety (abbreviated NHT) to replace the unstable conjugated double bond system of EβF, a series of novel EβF analogues containing the NHT moiety were synthesized via the reaction of substituted NHT rings with (E)-1-chloro-3,7-dimethylocta-2,6-diene. All the compounds were characterized by ¹H-NMR, (13)C-NMR, IR, and high resolution mass spectroscopy (HRMS). The bioassay results showed that all the analogues displayed different repellent and aphicidal activities against green peach aphid (Myzus persicae). Particularly, the analogue 4r exhibited obvious repellent activity (repellent proportion: 78.43%) and similar aphicidal activity against M. persicae (mortality: 82.05%) as the commercial compound pymetrozine (80.07%). A preliminary structure-activity relationship (SAR) study was also performed, which offered valuable clues for the design of further new EβF analogues. PMID:27347912

  17. Pyridine analogues of curcumin exhibit high activity for inhibiting CWR-22Rv1 human prostate cancer cell growth and androgen receptor activation

    PubMed Central

    ZHOU, DAI-YING; ZHAO, SU-QING; DU, ZHI-YUN; ZHENG, XI; ZHANG, KUN

    2016-01-01

    The concentrations required for curcumin to exert its anticancer activity (IC50, 20 µM) are difficult to achieve in the blood plasma of patients, due to the low bioavailability of the compound. Therefore, much effort has been devoted to the development of curcumin analogues that exhibit stronger anticancer activity and a lower IC50 than curcumin. The present study investigated twelve pyridine analogues of curcumin, labeled as groups AN, BN, EN and FN, to determine their effects in CWR-22Rv1 human prostate cancer cells. The inhibitory effects of these compounds on testosterone (TT)-induced androgen receptor (AR) activity was determined by performing an AR-linked luciferase assay and by TT-induced expression of prostate-specific antigen. The results of the current study suggested that the FN group of analogues had the strongest inhibitory effect of growth on CWR-22Rv1 cultured cells, and were the most potent inhibitor of AR activity compared with curcumin, and the AN, BN and EN analogues. Thus, the results of the present study indicate the inhibition of the AR pathways as a potential mechanism for the anticancer effect of curcumin analogues in human prostate cancer cells. Furthermore, curcumin analogues with pyridine as a distal ring and tetrahydrothiopyran-4-one as a linker may be good candidates for the development of novel drugs for the treatment of prostate cancer, by targeting the AR signaling pathway. PMID:27313760

  18. Antipsychotic profiles of TASP0443294, a novel and orally active positive allosteric modulator of metabotropic glutamate 2 receptor.

    PubMed

    Hikichi, Hirohiko; Hiyoshi, Tetsuaki; Marumo, Toshiyuki; Tomishima, Yasumitsu; Kaku, Ayaka; Iida, Izumi; Urabe, Hiroki; Tamita, Tomoko; Yasuhara, Akito; Karasawa, Jun-ichi; Chaki, Shigeyuki

    2015-03-01

    Glutamatergic dysfunction has been implicated in psychiatric disorders such as schizophrenia. The stimulation of metabotropic glutamate (mGlu) 2 receptor has been shown to be effective in a number of animal models of schizophrenia. In this study, we investigated the antipsychotic profiles of (2S)-5-methyl-2-{[4-(1,1,1-trifluoro-2-methylpropan-2-yl)phenoxy]methyl}-2,3-dihydroimidazo[2,1-b][1,3]oxazole-6-carboxamide (TASP0443294), a newly synthesized positive allosteric modulator of the mGlu2 receptor. TASP0443294 potentiated the response of human mGlu2 and rat mGlu2 receptors to glutamate with EC50 values of 277 and 149 nM, respectively, without affecting the glutamate response of human mGlu3 receptor. TASP0443294 was distributed in the brain and cerebrospinal fluid after peroral administration in rats. The peroral administration of TASP0443294 inhibited methamphetamine-induced hyperlocomotion in rats, which was attenuated by an mGlu2/3 receptor antagonist, and improved social memory impairment induced by 5R,10S-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) in rats. Furthermore, TASP0443294 reduced the ketamine-induced basal gamma hyperactivity in the prefrontal cortex and suppressed rapid eye movement (REM) sleep in rats. These findings indicate that TASP0443294 is an mGlu2 receptor positive allosteric modulator with antipsychotic activity, and that the suppression of aberrant gamma oscillations and REM sleep could be considered as neurophysiological biomarkers for TASP0443294. PMID:25837934

  19. Cellular Localization of Dieldrin and Structure–Activity Relationship of Dieldrin Analogues in Dopaminergic Cells

    PubMed Central

    Allen, Erin M. G.; Florang, Virginia R.; Davenport, Laurie L.; Jinsmaa, Yunden; Doorn, Jonathan A.

    2015-01-01

    The incidence of Parkinson’s disease (PD) correlates with environmental exposure to pesticides, such as the organochlorine insecticide, dieldrin. Previous studies found an increased concentration of the pesticide in the striatal region of the brains of PD patients and also that dieldrin adversely affects cellular processes associated with PD. These processes include mitochondrial function and reactive oxygen species production. However, the mechanism and specific cellular targets responsible for dieldrin-mediated cellular dysfunction and the structural components of dieldrin contributing to its toxicity (toxicophore) have not been fully defined. In order to identify the toxicophore of dieldrin, a structure–activity approach was used, with the toxicity profiles of numerous analogues of dieldrin (including aldrin, endrin, and cis-aldrin diol) assessed in PC6-3 cells. The MTT and lactate dehydrogenase (LDH) assays were used to monitor cell viability and membrane permeability after treatment with each compound. Cellular assays monitoring ROS production and extracellular dopamine metabolite levels were also used. Structure and stereochemistry for dieldrin were found to be very important for toxicity and other end points measured. Small changes in structure for dieldrin (e.g., comparison to the stereoisomer endrin) yielded significant differences in toxicity. Interestingly, the cis-diol metabolite of dieldrin was found to be significantly more toxic than the parent compound. Disruption of dopamine catabolism yielded elevated levels of the neurotoxin, 3,4-dihydroxyphenylacetaldehyde, for many organochlorines. Comparisons of the toxicity profiles for each dieldrin analogue indicated a structure-specific effect important for elucidating the mechanisms of dieldrin neurotoxicity. PMID:23763672

  20. Acetylated analogues of the microtubule-stabilizing agent discodermolide: preparation and biological activity.

    PubMed

    Gunasekera, S P; Longley, R E; Isbrucker, R A

    2001-02-01

    A series of eight discodermolide acetates have been prepared using natural (+)-discodermolide and evaluated for in vitro cytotoxicity against the cultured murine P-388 leukemia cells. The acetylated analogues showed a significant variation of cytotoxicity and suggested the importance of C-11 and C-17 hydroxyl groups for potency. The preparation and structure elucidation of the new analogues are described.

  1. Making Connections in Math: Activating a Prior Knowledge Analogue Matters for Learning

    ERIC Educational Resources Information Center

    Sidney, Pooja G.; Alibali, Martha W.

    2015-01-01

    This study investigated analogical transfer of conceptual structure from a prior-knowledge domain to support learning in a new domain of mathematics: division by fractions. Before a procedural lesson on division by fractions, fifth and sixth graders practiced with a surface analogue (other operations on fractions) or a structural analogue (whole…

  2. Synthesis and antiplasmodial activity of betulinic acid and ursolic acid analogues.

    PubMed

    Innocente, Adrine M; Silva, Gloria N S; Cruz, Laura Nogueira; Moraes, Miriam S; Nakabashi, Myna; Sonnet, Pascal; Gosmann, Grace; Garcia, Célia R S; Gnoatto, Simone C B

    2012-10-12

    More than 40% of the World population is at risk of contracting malaria, which affects primarily poor populations in tropical and subtropical areas. Antimalarial pharmacotherapy has utilised plant-derived products such as quinine and artemisinin as well as their derivatives. However, worldwide use of these antimalarials has caused the spread of resistant parasites, resulting in increased malaria morbidity and mortality. Considering that the literature has demonstrated the antimalarial potential of triterpenes, specially betulinic acid (1) and ursolic acid (2), this study investigated the antimalarial activity against P. falciparum chloroquine-sensitive 3D7 strain of some new derivatives of 1 and 2 with modifications at C-3 and C-28. The antiplasmodial study employed flow cytometry and spectrofluorimetric analyses using YOYO-1, dihydroethidium and Fluo4/AM for staining. Among the six analogues obtained, compounds 1c and 2c showed excellent activity (IC₅₀ = 220 and 175 nM, respectively) while 1a and b demonstrated good activity (IC₅₀ = 4 and 5 μM, respectively). After cytotoxicity evaluation against HEK293T cells, 1a was not toxic, while 1c and 2c showed IC₅₀ of 4 μM and a selectivity index (SI) value of 18 and 23, respectively. Moreover, compound 2c, which presents the best antiplasmodial activity, is involved in the calcium-regulated pathway(s).

  3. Green Tea Polyphenols Control Dysregulated Glutamate Dehydrogenase in Transgenic Mice by Hijacking the ADP Activation Site

    SciTech Connect

    Li, Changhong; Li, Ming; Chen, Pan; Narayan, Srinivas; Matschinsky, Franz M.; Bennett, Michael J.; Stanley, Charles A.; Smith, Thomas J.

    2012-05-09

    Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of L-glutamate and, in animals, is extensively regulated by a number of metabolites. Gain of function mutations in GDH that abrogate GTP inhibition cause the hyperinsulinism/hyperammonemia syndrome (HHS), resulting in increased pancreatic {beta}-cell responsiveness to leucine and susceptibility to hypoglycemia following high protein meals. We have previously shown that two of the polyphenols from green tea (epigallocatechin gallate (EGCG) and epicatechin gallate (ECG)) inhibit GDH in vitro and that EGCG blocks GDH-mediated insulin secretion in wild type rat islets. Using structural and site-directed mutagenesis studies, we demonstrate that ECG binds to the same site as the allosteric regulator, ADP. Perifusion assays using pancreatic islets from transgenic mice expressing a human HHS form of GDH demonstrate that the hyperresponse to glutamine caused by dysregulated GDH is blocked by the addition of EGCG. As observed in HHS patients, these transgenic mice are hypersensitive to amino acid feeding, and this is abrogated by oral administration of EGCG prior to challenge. Finally, the low basal blood glucose level in the HHS mouse model is improved upon chronic administration of EGCG. These results suggest that this common natural product or some derivative thereof may prove useful in controlling this genetic disorder. Of broader clinical implication is that other groups have shown that restriction of glutamine catabolism via these GDH inhibitors can be useful in treating various tumors. This HHS transgenic mouse model offers a highly useful means to test these agents in vivo.

  4. Green tea polyphenols control dysregulated glutamate dehydrogenase in transgenic mice by hijacking the ADP activation site.

    PubMed

    Li, Changhong; Li, Ming; Chen, Pan; Narayan, Srinivas; Matschinsky, Franz M; Bennett, Michael J; Stanley, Charles A; Smith, Thomas J

    2011-09-30

    Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of L-glutamate and, in animals, is extensively regulated by a number of metabolites. Gain of function mutations in GDH that abrogate GTP inhibition cause the hyperinsulinism/hyperammonemia syndrome (HHS), resulting in increased pancreatic β-cell responsiveness to leucine and susceptibility to hypoglycemia following high protein meals. We have previously shown that two of the polyphenols from green tea (epigallocatechin gallate (EGCG) and epicatechin gallate (ECG)) inhibit GDH in vitro and that EGCG blocks GDH-mediated insulin secretion in wild type rat islets. Using structural and site-directed mutagenesis studies, we demonstrate that ECG binds to the same site as the allosteric regulator, ADP. Perifusion assays using pancreatic islets from transgenic mice expressing a human HHS form of GDH demonstrate that the hyperresponse to glutamine caused by dysregulated GDH is blocked by the addition of EGCG. As observed in HHS patients, these transgenic mice are hypersensitive to amino acid feeding, and this is abrogated by oral administration of EGCG prior to challenge. Finally, the low basal blood glucose level in the HHS mouse model is improved upon chronic administration of EGCG. These results suggest that this common natural product or some derivative thereof may prove useful in controlling this genetic disorder. Of broader clinical implication is that other groups have shown that restriction of glutamine catabolism via these GDH inhibitors can be useful in treating various tumors. This HHS transgenic mouse model offers a highly useful means to test these agents in vivo.

  5. Design and Synthesis of Systemically Active Metabotropic Glutamate Subtype-2 and -3 (mGlu2/3) Receptor Positive Allosteric Modulators (PAMs): Pharmacological Characterization and Assessment in a Rat Model of Cocaine Dependence

    PubMed Central

    2015-01-01

    As part of our ongoing small-molecule metabotropic glutamate (mGlu) receptor positive allosteric modulator (PAM) research, we performed structure–activity relationship (SAR) studies around a series of group II mGlu PAMs. Initial analogues exhibited weak activity as mGlu2 receptor PAMs and no activity at mGlu3. Compound optimization led to the identification of potent mGlu2/3 selective PAMs with no in vitro activity at mGlu1,4–8 or 45 other CNS receptors. In vitro pharmacological characterization of representative compound 44 indicated agonist-PAM activity toward mGlu2 and PAM activity at mGlu3. The most potent mGlu2/3 PAMs were characterized in assays predictive of ADME/T and pharmacokinetic (PK) properties, allowing the discovery of systemically active mGlu2/3 PAMs. On the basis of its overall profile, compound 74 was selected for behavioral studies and was shown to dose-dependently decrease cocaine self-administration in rats after intraperitoneal administration. These mGlu2/3 receptor PAMs have significant potential as small molecule tools for investigating group II mGlu pharmacology. PMID:24735492

  6. Design and synthesis of systemically active metabotropic glutamate subtype-2 and -3 (mGlu2/3) receptor positive allosteric modulators (PAMs): pharmacological characterization and assessment in a rat model of cocaine dependence.

    PubMed

    Dhanya, Raveendra-Panickar; Sheffler, Douglas J; Dahl, Russell; Davis, Melinda; Lee, Pooi San; Yang, Li; Nickols, Hilary Highfield; Cho, Hyekyung P; Smith, Layton H; D'Souza, Manoranjan S; Conn, P Jeffrey; Der-Avakian, Andre; Markou, Athina; Cosford, Nicholas D P

    2014-05-22

    As part of our ongoing small-molecule metabotropic glutamate (mGlu) receptor positive allosteric modulator (PAM) research, we performed structure-activity relationship (SAR) studies around a series of group II mGlu PAMs. Initial analogues exhibited weak activity as mGlu2 receptor PAMs and no activity at mGlu3. Compound optimization led to the identification of potent mGlu2/3 selective PAMs with no in vitro activity at mGlu1,4-8 or 45 other CNS receptors. In vitro pharmacological characterization of representative compound 44 indicated agonist-PAM activity toward mGlu2 and PAM activity at mGlu3. The most potent mGlu2/3 PAMs were characterized in assays predictive of ADME/T and pharmacokinetic (PK) properties, allowing the discovery of systemically active mGlu2/3 PAMs. On the basis of its overall profile, compound 74 was selected for behavioral studies and was shown to dose-dependently decrease cocaine self-administration in rats after intraperitoneal administration. These mGlu2/3 receptor PAMs have significant potential as small molecule tools for investigating group II mGlu pharmacology. PMID:24735492

  7. Neuroprotection Promoted by Guanosine Depends on Glutamine Synthetase and Glutamate Transporters Activity in Hippocampal Slices Subjected to Oxygen/Glucose Deprivation.

    PubMed

    Dal-Cim, Tharine; Martins, Wagner C; Thomaz, Daniel T; Coelho, Victor; Poluceno, Gabriela Godoy; Lanznaster, Débora; Vandresen-Filho, Samuel; Tasca, Carla I

    2016-05-01

    Guanosine (GUO) has been shown to act as a neuroprotective agent against glutamatergic excitotoxicity by increasing glutamate uptake and decreasing its release. In this study, a putative effect of GUO action on glutamate transporters activity modulation was assessed in hippocampal slices subjected to oxygen and glucose deprivation (OGD), an in vitro model of brain ischemia. Slices subjected to OGD showed increased excitatory amino acids release (measured by D-[(3)H]aspartate release) that was prevented in the presence of GUO (100 µM). The glutamate transporter blockers, DL-TBOA (10 µM), DHK (100 µM, selective inhibitor of GLT-1), and sulfasalazine (SAS, 250 µM, Xc(-) system inhibitor) decreased OGD-induced D-aspartate release. Interestingly, DHK or DL-TBOA blocked the decrease in glutamate release induced by GUO, whereas SAS did not modify the GUO effect. GUO protected hippocampal slices from cellular damage by modulation of glutamate transporters, however selective blockade of GLT-1 or Xc- system only did not affect this protective action of GUO. OGD decreased hippocampal glutamine synthetase (GS) activity and GUO recovered GS activity to control levels without altering the kinetic parameters of GS activity, thus suggesting GUO does not directly interact with GS. Additionally, the pharmacological inhibition of GS activity with methionine sulfoximine abolished the effect of GUO in reducing D-aspartate release and cellular damage evoked by OGD. Altogether, results in hippocampal slices subjected to OGD show that GUO counteracts the release of excitatory amino acids, stimulates the activity of GS, and decreases the cellular damage by modulation of glutamate transporters activity.

  8. Side-chain interactions in the regulatory domain of human glutamate dehydrogenase determine basal activity and regulation.

    PubMed

    Mastorodemos, Vasileios; Kanavouras, Konstantinos; Sundaram, Shobana; Providaki, Maria; Petraki, Zoe; Kokkinidis, Michael; Zaganas, Ioannis; Logothetis, Diomedes E; Plaitakis, Andreas

    2015-04-01

    Glutamate Dehydrogenase (GDH) is central to the metabolism of glutamate, a major excitatory transmitter in mammalian central nervous system (CNS). hGDH1 is activated by ADP and L-leucine and powerfully inhibited by GTP. Besides this housekeeping hGDH1, duplication led to an hGDH2 isoform that is expressed in the human brain dissociating its function from GTP control. The novel enzyme has reduced basal activity (4-6% of capacity) while remaining remarkably responsive to ADP/L-leucine activation. While the molecular basis of this evolutionary adaptation remains unclear, substitution of Ser for Arg443 in hGDH1 is shown to diminish basal activity (< 2% of capacity) and abrogate L-leucine activation. To explore whether the Arg443Ser mutation disrupts hydrogen bonding between Arg443 and Ser409 of adjacent monomers in the regulatory domain ('antenna'), we replaced Ser409 by Arg or Asp in hGDH1. The Ser409Arg-1 change essentially replicated the Arg443Ser-1 mutation effects. Molecular dynamics simulation predicted that Ser409 and Arg443 of neighboring monomers come in close proximity in the open conformation and that introduction of Ser443-1 or Arg409-1 causes them to separate with the swap mutation (Arg409/Ser443) reinstating their proximity. A swapped Ser409Arg/Arg443Ser-1 mutant protein, obtained in recombinant form, regained most of the wild-type hGDH1 properties. Also, when Ser443 was replaced by Arg443 in hGDH2 (as occurs in hGDH1), the Ser443Arg-2 mutant acquired most of the hGDH1 properties. Hence, side-chain interactions between 409 and 443 positions in the 'antenna' region of hGDHs are crucial for basal catalytic activity, allosteric regulation, and relative resistance to thermal inactivation. PMID:25620628

  9. Inhibition of guinea-pig lymphocyte activation by histamine and histamine analogues.

    PubMed Central

    Beets, J. L.; Dale, M. M.

    1979-01-01

    1 The incorporation of [3H]-thymidine into guinea-pig lymphocytes stimulated by a plant lectin (concanavalin A), soluble antigen (tuberculin (P.P.D.)) and syngeneic hepatoma cells, was partially inhibited (50%) by histamine in vitro. 2 The effect of histamine on both mitogen and antigen dose-response curves suggests a non-competitive, probably physiological antagonism. 3 The inhibitory dose range of histamine lay between 10 nM and 30 microM with an ID50 of approximately 400 nM. 4 The potency order for histamine analogues for the inhibition of lymphocyte activation was histamine greater than or equal to 4-methylhistamine greater than 2-methylhistamine greater than 3-methylhistamine. This is in accord with the mediation of the response through an H2-receptor. 5 H2-receptor antagonists reversed the inhibitory effect of histamine in a dose-related manner, but both metiamide and burimamide, in high concentrations, augmented lymphocyte activation in their own right. This precluded the determination of affinity constants and made it impossible to state with certainty that the inhibition of lymphocyte activation by histamine was mediated by an H2-receptor. PMID:526705

  10. John Montgomery's legacy: carbocyclic adenosine analogues as SAH hydrolase inhibitors with broad-spectrum antiviral activity.

    PubMed

    De Clercq, Erik

    2005-01-01

    Ever since the S-adenosylhomocysteine (AdoHcy, SAH) hydrolase was recognized as a pharmacological target for antiviral agents (J. A. Montgomery et al., J. Med. Chem. 25:626-629, 1982), an increasing number of adenosine, acyclic adenosine, and carbocyclic adenosine analogues have been described as potent SAH hydrolase inhibitors endowed with broad-spectrum antiviral activity. The antiviral activity spectrum of the SAH hydrolase inhibitors include pox-, rhabdo-, filo-, arena-, paramyxo-, reo-, and retroviruses. Among the most potent SAH hydrolase inhibitors and antiviral agents rank carbocyclic 3-deazaadenosine (C-c3 Ado), neplanocin A, 3-deazaneplanocin A, the 5'-nor derivatives of carbocyclic adenosine (C-Ado, aristeromycin), and the 2-halo (i.e., 2-fluoro) and 6'-R-alkyl (i.e., 6'-R-methyl) derivatives of neplanocin A. These compounds are particularly active against poxviruses (i.e., vaccinia virus), and rhabdoviruses (i.e., vesicular stomatitis virus). The in vivo efficacy of C-c3 Ado and 3-deazaneplanocin A has been established in mouse models for vaccinia virus, vesicular stomatitis virus, and Ebola virus. SAH hydrolase inhibitors such as C-c3Ado and 3-deazaneplanocin A should in thefirst place be considered for therapeutic (or prophylactic) use against poxvirus infections, including smallpox, and hemorrhagic fever virus infections such as Ebola. PMID:16438025

  11. Synthesis and antioxidant activity of hydroxylated phenanthrenes as cis-restricted resveratrol analogues.

    PubMed

    Ding, De-Jun; Cao, Xiao-Yan; Dai, Fang; Li, Xiu-Zhuang; Liu, Guo-Yun; Lin, Dong; Fu, Xing; Jin, Xiao-Ling; Zhou, Bo

    2012-12-01

    Five hydroxylated phenanthrenes as "cis-configuration-fixed" resveratrol analogues differing in the number and position of the hydroxyl groups were designed and synthesized. Their antioxidant activity was studied by ferric reducing antioxidant power, 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging, and DNA strand breakage-inhibiting assays, corresponding to their electron-donating, hydrogen-transfer and DNA-protecting abilities, respectively. In the above assays, their activity depends significantly on the number and position of the hydroxyl groups, and most of them are more effective than resveratrol. Noticeably, compound 9b (2,4,6-trihydroxyl phenanthrene) with the same hydroxyl group substitutions as resveratrol, is superior to the reference compound, highlighting the importance of extension of the conjugation over multiple aromatic-rings. Similar activity sequences were obtained in different experimental models, but the appreciable differences could contribute detailed insights into antioxidant mechanisms. Based on these results, the hydroxylated phenanthrenes may be considered as a novel type of resveratrol-directed antioxidants.

  12. Xanthurenic Acid Activates mGlu2/3 Metabotropic Glutamate Receptors and is a Potential Trait Marker for Schizophrenia.

    PubMed

    Fazio, Francesco; Lionetto, Luana; Curto, Martina; Iacovelli, Luisa; Cavallari, Michele; Zappulla, Cristina; Ulivieri, Martina; Napoletano, Flavia; Capi, Matilde; Corigliano, Valentina; Scaccianoce, Sergio; Caruso, Alessandra; Miele, Jessica; De Fusco, Antonio; Di Menna, Luisa; Comparelli, Anna; De Carolis, Antonella; Gradini, Roberto; Nisticò, Robert; De Blasi, Antonio; Girardi, Paolo; Bruno, Valeria; Battaglia, Giuseppe; Nicoletti, Ferdinando; Simmaco, Maurizio

    2015-12-08

    The kynurenine pathway of tryptophan metabolism has been implicated in the pathophysiology of psychiatric disorders, including schizophrenia. We report here that the kynurenine metabolite, xanturenic acid (XA), interacts with, and activates mGlu2 and mGlu3 metabotropic glutamate receptors in heterologous expression systems. However, the molecular nature of this interaction is unknown, and our data cannot exclude that XA acts primarily on other targets, such as the vesicular glutamate transporter, in the CNS. Systemic administration of XA in mice produced antipsychotic-like effects in the MK-801-induced model of hyperactivity. This effect required the presence of mGlu2 receptors and was abrogated by the preferential mGlu2/3 receptor antagonist, LY341495. Because the mGlu2 receptor is a potential drug target in the treatment of schizophrenia, we decided to measure serum levels of XA and other kynurenine metabolites in patients affected by schizophrenia. Serum XA levels were largely reduced in a large cohort of patients affected by schizophrenia, and, in patients with first-episode schizophrenia, levels remained low after 12 months of antipsychotic medication. As opposed to other kynurenine metabolites, XA levels were also significantly reduced in first-degree relatives of patients affected by schizophrenia. We suggest that lowered serum XA levels might represent a novel trait marker for schizophrenia.

  13. Xanthurenic Acid Activates mGlu2/3 Metabotropic Glutamate Receptors and is a Potential Trait Marker for Schizophrenia.

    PubMed

    Fazio, Francesco; Lionetto, Luana; Curto, Martina; Iacovelli, Luisa; Cavallari, Michele; Zappulla, Cristina; Ulivieri, Martina; Napoletano, Flavia; Capi, Matilde; Corigliano, Valentina; Scaccianoce, Sergio; Caruso, Alessandra; Miele, Jessica; De Fusco, Antonio; Di Menna, Luisa; Comparelli, Anna; De Carolis, Antonella; Gradini, Roberto; Nisticò, Robert; De Blasi, Antonio; Girardi, Paolo; Bruno, Valeria; Battaglia, Giuseppe; Nicoletti, Ferdinando; Simmaco, Maurizio

    2015-01-01

    The kynurenine pathway of tryptophan metabolism has been implicated in the pathophysiology of psychiatric disorders, including schizophrenia. We report here that the kynurenine metabolite, xanturenic acid (XA), interacts with, and activates mGlu2 and mGlu3 metabotropic glutamate receptors in heterologous expression systems. However, the molecular nature of this interaction is unknown, and our data cannot exclude that XA acts primarily on other targets, such as the vesicular glutamate transporter, in the CNS. Systemic administration of XA in mice produced antipsychotic-like effects in the MK-801-induced model of hyperactivity. This effect required the presence of mGlu2 receptors and was abrogated by the preferential mGlu2/3 receptor antagonist, LY341495. Because the mGlu2 receptor is a potential drug target in the treatment of schizophrenia, we decided to measure serum levels of XA and other kynurenine metabolites in patients affected by schizophrenia. Serum XA levels were largely reduced in a large cohort of patients affected by schizophrenia, and, in patients with first-episode schizophrenia, levels remained low after 12 months of antipsychotic medication. As opposed to other kynurenine metabolites, XA levels were also significantly reduced in first-degree relatives of patients affected by schizophrenia. We suggest that lowered serum XA levels might represent a novel trait marker for schizophrenia. PMID:26643205

  14. Xanthurenic Acid Activates mGlu2/3 Metabotropic Glutamate Receptors and is a Potential Trait Marker for Schizophrenia

    PubMed Central

    Fazio, Francesco; Lionetto, Luana; Curto, Martina; Iacovelli, Luisa; Cavallari, Michele; Zappulla, Cristina; Ulivieri, Martina; Napoletano, Flavia; Capi, Matilde; Corigliano, Valentina; Scaccianoce, Sergio; Caruso, Alessandra; Miele, Jessica; De Fusco, Antonio; Di Menna, Luisa; Comparelli, Anna; De Carolis, Antonella; Gradini, Roberto; Nisticò, Robert; De Blasi, Antonio; Girardi, Paolo; Bruno, Valeria; Battaglia, Giuseppe; Nicoletti, Ferdinando; Simmaco, Maurizio

    2015-01-01

    The kynurenine pathway of tryptophan metabolism has been implicated in the pathophysiology of psychiatric disorders, including schizophrenia. We report here that the kynurenine metabolite, xanturenic acid (XA), interacts with, and activates mGlu2 and mGlu3 metabotropic glutamate receptors in heterologous expression systems. However, the molecular nature of this interaction is unknown, and our data cannot exclude that XA acts primarily on other targets, such as the vesicular glutamate transporter, in the CNS. Systemic administration of XA in mice produced antipsychotic-like effects in the MK-801-induced model of hyperactivity. This effect required the presence of mGlu2 receptors and was abrogated by the preferential mGlu2/3 receptor antagonist, LY341495. Because the mGlu2 receptor is a potential drug target in the treatment of schizophrenia, we decided to measure serum levels of XA and other kynurenine metabolites in patients affected by schizophrenia. Serum XA levels were largely reduced in a large cohort of patients affected by schizophrenia, and, in patients with first-episode schizophrenia, levels remained low after 12 months of antipsychotic medication. As opposed to other kynurenine metabolites, XA levels were also significantly reduced in first-degree relatives of patients affected by schizophrenia. We suggest that lowered serum XA levels might represent a novel trait marker for schizophrenia. PMID:26643205

  15. Curcumin attenuates glutamate neurotoxicity in the hippocampus by suppression of ER stress-associated TXNIP/NLRP3 inflammasome activation in a manner dependent on AMPK

    SciTech Connect

    Li, Ying; Li, Jia; Li, Shanshan; Li, Yi; Wang, Xiangxiang; Liu, Baolin; Fu, Qiang; Ma, Shiping

    2015-07-01

    Curcumin is a natural polyphenolic compound in Curcuma longa with beneficial effects on neuronal protection. This study aims to investigate the action of curcumin in the hippocampus subjected to glutamate neurotoxicity. Glutamate stimulation induced reactive oxygen species (ROS), endoplasmic reticulum stress (ER stress) and TXNIP/NLRP3 inflammasome activation, leading to damage in the hippocampus. Curcumin treatment in the hippocampus or SH-SY5Y cells inhibited IRE1α and PERK phosphorylation with suppression of intracellular ROS production. Curcumin increased AMPK activity and knockdown of AMPKα with specific siRNA abrogated its inhibitory effects on IRE1α and PERK phosphorylation, indicating that AMPK activity was essential for the suppression of ER stress. As a result, curcumin reduced TXNIP expression and inhibited NLRP3 inflammasome activation by downregulation of NLRP3 and cleaved caspase-1 induction, and thus reduced IL-1β secretion. Specific fluorescent probe and flow cytometry analysis showed that curcumin prevented mitochondrial malfunction and protected cell survival from glutamate neurotoxicity. Moreover, oral administration of curcumin reduced brain infarct volume and attenuated neuronal damage in rats subjected to middle cerebral artery occlusion. Immunohistochemistry showed that curcumin inhibited p-IRE1α, p-PERK and NLRP3 expression in hippocampus CA1 region. Together, these results showed that curcumin attenuated glutamate neurotoxicity by inhibiting ER stress-associated TXNIP/NLRP3 inflammasome activation via the regulation of AMPK, and thereby protected the hippocampus from ischemic insult. - Highlights: • Curcumin attenuates glutamate neurotoxicity in the hippocampus. • Curcumin suppresses ER stress in glutamate-induced hippocampus slices. • Curcumin inhibits TXNIP/NLRP3 inflammasome activation. • Regulation of AMPK by curcumin contributes to suppressing ER stress.

  16. Exploring the active conformation of cyclohexane carboxylate positive allosteric modulators of the type 4 metabotropic glutamate receptor.

    PubMed

    Rovira, Xavier; Harrak, Youssef; Trapero, Ana; González-Bulnes, Patricia; Malhaire, Fanny; Pin, Jean-Philippe; Goudet, Cyril; Giraldo, Jesús; Llebaria, Amadeu

    2014-12-01

    The active conformation of a family of metabotropic glutamate receptor subtype 4 (mGlu4 ) positive allosteric modulators (PAMs) with the cyclohexane 1,2-dicarboxylic scaffold present in cis-2-(3,5-dichlorophenylcarbamoyl)cyclohexanecarboxylic acid (VU0155041) was investigated by testing structurally similar six-membered ring compounds that have a locked conformation. The norbornane and cyclohexane molecules designed as mGlu4 conformational probes and the enantiomers of the trans diastereomer were computationally characterized and tested in mGlu4 pharmacological assays. The results support a VU0155041 active conformation, with the chair cyclohexane having the aromatic amide substituent in an axial position and the carboxylate in an equatorial position. Moreover, the receptor displays enantiomeric discrimination of the chiral PAMs. The constructed pharmacophore characterized a highly constrained mGlu4 allosteric binding site, thus providing a step forward in structure-based drug design for mGlu4 PAMs.

  17. Enhanced degradation of benzene by percarbonate activated with Fe(II)-glutamate complex.

    PubMed

    Fu, Xiaori; Gu, Xiaogang; Lu, Shuguang; Miao, Zhouwei; Xu, Minhui; Zhang, Xiang; Danish, Muhammad; Cui, Hang; Farooq, Usman; Qiu, Zhaofu; Sui, Qian

    2016-04-01

    Effective degradation of benzene was achieved in sodium percarbonate (SPC)/Fe(II)-Glu system. The presence of glutamate (Glu) could enhance the regeneration of Fe(III) to Fe(II), which ensures the benzene degradation efficiency at wider pH range and eliminate the influence of HCO3 (-) in low concentration. Meanwhile, the significant scavenging effects of high HCO3 (-) concentration could also be overcome by increasing the Glu/SPC/Fe(II)/benzene molar ratio. Free radical probe compound tests, free radical scavenger tests, and electron paramagnetic resonance (EPR) analysis were conducted to explore the reaction mechanism for benzene degradation, in which hydroxyl radical (HO•) and superoxide anion radical (O2 (•-)) were confirmed as the predominant species responsible for benzene degradation. In addition, the results obtained in actual groundwater test strongly indicated that SPC/Fe(II)-Glu system is applicable for the remediation of benzene-contaminated groundwater in practice. PMID:26662563

  18. Enhanced degradation of benzene by percarbonate activated with Fe(II)-glutamate complex.

    PubMed

    Fu, Xiaori; Gu, Xiaogang; Lu, Shuguang; Miao, Zhouwei; Xu, Minhui; Zhang, Xiang; Danish, Muhammad; Cui, Hang; Farooq, Usman; Qiu, Zhaofu; Sui, Qian

    2016-04-01

    Effective degradation of benzene was achieved in sodium percarbonate (SPC)/Fe(II)-Glu system. The presence of glutamate (Glu) could enhance the regeneration of Fe(III) to Fe(II), which ensures the benzene degradation efficiency at wider pH range and eliminate the influence of HCO3 (-) in low concentration. Meanwhile, the significant scavenging effects of high HCO3 (-) concentration could also be overcome by increasing the Glu/SPC/Fe(II)/benzene molar ratio. Free radical probe compound tests, free radical scavenger tests, and electron paramagnetic resonance (EPR) analysis were conducted to explore the reaction mechanism for benzene degradation, in which hydroxyl radical (HO•) and superoxide anion radical (O2 (•-)) were confirmed as the predominant species responsible for benzene degradation. In addition, the results obtained in actual groundwater test strongly indicated that SPC/Fe(II)-Glu system is applicable for the remediation of benzene-contaminated groundwater in practice.

  19. Long-Term Activation of Group I Metabotropic Glutamate Receptors Increases Functional TRPV1-Expressing Neurons in Mouse Dorsal Root Ganglia

    PubMed Central

    Masuoka, Takayoshi; Kudo, Makiko; Yoshida, Junko; Ishibashi, Takaharu; Muramatsu, Ikunobu; Kato, Nobuo; Imaizumi, Noriko; Nishio, Matomo

    2016-01-01

    Damaged tissues release glutamate and other chemical mediators for several hours. These chemical mediators contribute to modulation of pruritus and pain. Herein, we investigated the effects of long-term activation of excitatory glutamate receptors on functional expression of transient receptor potential vaniloid type 1 (TRPV1) in dorsal root ganglion (DRG) neurons and then on thermal pain behavior. In order to detect the TRPV1-mediated responses in cultured DRG neurons, we monitored intracellular calcium responses to capsaicin, a TRPV1 agonist, with Fura-2. Long-term (4 h) treatment with glutamate receptor agonists (glutamate, quisqualate or DHPG) increased the proportion of neurons responding to capsaicin through activation of metabotropic glutamate receptor mGluR1, and only partially through the activation of mGluR5; engagement of these receptors was evident in neurons responding to allylisothiocyanate (AITC), a transient receptor potential ankyrin type 1 (TRPA1) agonist. Increase in the proportion was suppressed by phospholipase C (PLC), protein kinase C, mitogen/extracellular signal-regulated kinase, p38 mitogen-activated protein kinase or transcription inhibitors. Whole-cell recording was performed to record TRPV1-mediated membrane current; TRPV1 current density significantly increased in the AITC-sensitive neurons after the quisqualate treatment. To elucidate the physiological significance of this phenomenon, a hot plate test was performed. Intraplantar injection of quisqualate or DHPG induced heat hyperalgesia that lasted for 4 h post injection. This chronic hyperalgesia was attenuated by treatment with either mGluR1 or mGluR5 antagonists. These results suggest that long-term activation of mGluR1/5 by peripherally released glutamate may increase the number of neurons expressing functional TRPV1 in DRG, which may be strongly associated with chronic hyperalgesia. PMID:27064319

  20. Docking, Synthesis and Antiproliferative Activity of N-Acylhydrazone Derivatives Designed as Combretastatin A4 Analogues

    PubMed Central

    do Amaral, Daniel Nascimento; Cavalcanti, Bruno C.; Bezerra, Daniel P.; Ferreira, Paulo Michel P.; Castro, Rosane de Paula; Sabino, José Ricardo; Machado, Camila Maria Longo; Chammas, Roger; Pessoa, Claudia; Sant'Anna, Carlos M. R.; Barreiro, Eliezer J.; Lima, Lídia Moreira

    2014-01-01

    Cancer is the second most common cause of death in the USA. Among the known classes of anticancer agents, the microtubule-targeted antimitotic drugs are considered to be one of the most important. They are usually classified into microtubule-destabilizing (e.g., Vinca alkaloids) and microtubule-stabilizing (e.g., paclitaxel) agents. Combretastatin A4 (CA-4), which is a natural stilbene isolated from Combretum caffrum, is a microtubule-destabilizing agent that binds to the colchicine domain on β-tubulin and exhibits a lower toxicity profile than paclitaxel or the Vinca alkaloids. In this paper, we describe the docking study, synthesis, antiproliferative activity and selectivity index of the N-acylhydrazone derivatives (5a–r) designed as CA-4 analogues. The essential structural requirements for molecular recognition by the colchicine binding site of β-tubulin were recognized, and several compounds with moderate to high antiproliferative potency (IC50 values ≤18 µM and ≥4 nM) were identified. Among these active compounds, LASSBio-1586 (5b) emerged as a simple antitumor drug candidate, which is capable of inhibiting microtubule polymerization and possesses a broad in vitro and in vivo antiproliferative profile, as well as a better selectivity index than the prototype CA-4, indicating improved selective cytotoxicity toward cancer cells. PMID:24614859

  1. Anti-proliferation activity of synthetic ajoene analogues on cancer cell-lines.

    PubMed

    Kaschula, Catherine H; Hunter, Roger; Hassan, Hassan T; Stellenboom, Nashia; Cotton, Jonathan; Zhai, Xiao Q; Parker, M Iqbal

    2011-03-01

    The ability of garlic preparations to inhibit cancer cell-growth has been attributed to a group of structurally-related organosulfur compounds found in the crushed clove. Historically, interest has centred on three such compounds as allicin, diallyl disulfide and diallyl trisulfide, with less interest on E- and Z-ajoene. A recently developed synthetic route from our laboratory for preparing ajoene analogues allows access to derivatives containing the sulfoxide / vinyl disulfide core whilst varying the terminal end-group functionality. A small library has been synthesized and an advanced lead with p-methoxybenzyl end groups (8) identified. Data on the in vitro anti-proliferation activity of compound (8) is presented here against six cancer cell-lines in comparison with that of Z- and E-ajoene to reveal an enhancement in activity of up to twelvefold. In addition, a modest selectivity is observed for tumour over normal cell-lines of up to threefold. Data on ajoene and its derivatives is presented in the context of chemosensitization in drug-resistance, and ideas on ajoene's mode of action at the molecular level are presented and discussed.

  2. Phenylpropanoid Glycoside Analogues: Enzymatic Synthesis, Antioxidant Activity and Theoretical Study of Their Free Radical Scavenger Mechanism

    PubMed Central

    López-Munguía, Agustín; Hernández-Romero, Yanet; Pedraza-Chaverri, José; Miranda-Molina, Alfonso; Regla, Ignacio; Martínez, Ana; Castillo, Edmundo

    2011-01-01

    Phenylpropanoid glycosides (PPGs) are natural compounds present in several medicinal plants that have high antioxidant power and diverse biological activities. Because of their low content in plants (less than 5% w/w), several chemical synthetic routes to produce PPGs have been developed, but their synthesis is a time consuming process and the achieved yields are often low. In this study, an alternative and efficient two-step biosynthetic route to obtain natural PPG analogues is reported for the first time. Two galactosides were initially synthesized from vanillyl alcohol and homovanillyl alcohol by a transgalactosylation reaction catalyzed by Kluyveromyces lactis β-galactosidase in saturated lactose solutions with a 30%–35% yield. To synthesize PPGs, the galactoconjugates were esterified with saturated and unsaturated hydroxycinnamic acid derivatives using Candida antarctica Lipase B (CaL-B) as a biocatalyst with 40%–60% yields. The scavenging ability of the phenolic raw materials, intermediates and PPGs was evaluated by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) method. It was found that the biosynthesized PPGs had higher scavenging abilities when compared to ascorbic acid, the reference compound, while their antioxidant activities were found similar to that of natural PPGs. Moreover, density functional theory (DFT) calculations were used to determine that the PPGs antioxidant mechanism proceeds through a sequential proton loss single electron transfer (SPLET). The enzymatic process reported in this study is an efficient and versatile route to obtain PPGs from different phenylpropanoid acids, sugars and phenolic alcohols. PMID:21674039

  3. The cystine/glutamate antiporter regulates indoleamine 2,3-dioxygenase protein levels and enzymatic activity in human dendritic cells.

    PubMed

    Mattox, Mildred L; D'Angelo, June A; Grimes, Zachary M; Fiebiger, Edda; Dickinson, Bonny L

    2012-11-30

    Indoleamine 2,3-dioxygenase (IDO) is the rate-limiting enzyme in the tryptophan-catabolizing pathway and a key regulator of peripheral immune tolerance. As the suppressive effects of IDO are predominantly mediated by dendritic cells (DCs) and IDO-competent DCs promote long-term immunologic tolerance, a detailed understanding of how IDO expression and activity is regulated in these cells is central to the rational design of therapies to induce robust immune tolerance. We previously reported that the cystine/glutamate antiporter modulates the functional expression of IDO in human monocyte-derived DCs. Specifically, we showed that blocking antiporter uptake of cystine significantly increased both IDO mRNA and IDO enzymatic activity and that this correlated with impaired DC presentation of exogenous antigen to T cells via MHC class II and the cross-presentation pathway. The antiporter regulates intracellular and extracellular redox by transporting cystine into the cell in exchange for glutamate. Intracellular cystine is reduced to cysteine to support biosynthesis of the major cellular antioxidant glutathione and cysteine is exported from the cell where it functions as an extracellular antioxidant. Here we show that antiporter control of IDO expression in DCs is reversible, independent of interferon-γ, regulated by redox, and requires active protein synthesis. These findings highlight a role for antiporter regulation of cellular redox as a critical control point for modulating IDO expression and activity in DCs. Thus, systemic disease and aging, processes that perturb redox homeostasis, may adversely affect immunity by promoting the generation of IDO-competent DCs.

  4. The cystine/glutamate antiporter regulates indoleamine 2,3-dioxygenase protein levels and enzymatic activity in human dendritic cells

    PubMed Central

    Mattox, Mildred L; D’Angelo, June A; Grimes, Zachary M; Fiebiger, Edda; Dickinson, Bonny L

    2012-01-01

    Indoleamine 2,3-dioxygenase (IDO) is the rate-limiting enzyme in the tryptophan-catabolizing pathway and a key regulator of peripheral immune tolerance. As the suppressive effects of IDO are predominantly mediated by dendritic cells (DCs) and IDO-competent DCs promote long-term immunologic tolerance, a detailed understanding of how IDO expression and activity is regulated in these cells is central to the rational design of therapies to induce robust immune tolerance. We previously reported that the cystine/glutamate antiporter modulates the functional expression of IDO in human monocyte-derived DCs. Specifically, we showed that blocking antiporter uptake of cystine significantly increased both IDO mRNA and IDO enzymatic activity and that this correlated with impaired DC presentation of exogenous antigen to T cells via MHC class II and the cross-presentation pathway. The antiporter regulates intracellular and extracellular redox by transporting cystine into the cell in exchange for glutamate. Intracellular cystine is reduced to cysteine to support biosynthesis of the major cellular antioxidant glutathione and cysteine is exported from the cell where it functions as an extracellular antioxidant. Here we show that antiporter control of IDO expression in DCs is reversible, independent of interferon-γ, regulated by redox, and requires active protein synthesis. These findings highlight a role for antiporter regulation of cellular redox as a critical control point for modulating IDO expression and activity in DCs. Thus, systemic disease and aging, processes that perturb redox homeostasis, may adversely affect immunity by promoting the generation of IDO-competent DCs. PMID:23243629

  5. Activation of group II metabotropic glutamate receptors underlies microglial reactivity and neurotoxicity following stimulation with chromogranin A, a peptide up-regulated in Alzheimer's disease.

    PubMed

    Taylor, D L; Diemel, L T; Cuzner, M L; Pocock, J M

    2002-09-01

    Regulation of microglial reactivity and neurotoxicity is critical for neuroprotection in neurodegenerative diseases. Here we report that microglia possess functional group II metabotropic glutamate receptors, expressing mRNA and receptor protein for mGlu2 and mGlu3, negatively coupled to adenylate cyclase. Two different agonists of these receptors were able to induce a neurotoxic microglial phenotype which was attenuated by a specific antagonist. Chromogranin A, a secretory peptide expressed in amyloid plaques in Alzheimer's disease, activates microglia to a reactive neurotoxic phenotype. Chromogranin A-induced microglial activation and subsequent neurotoxicity may also involve an underlying stimulation of group II metabotropic glutamate receptors since their inhibition reduced chromogranin A-induced microglial reactivity and neurotoxicity. These results show that selective inhibition of microglial group II metabotropic glutamate receptors has a positive impact on neuronal survival, and may prove a therapeutic target in Alzheimer's disease. PMID:12358765

  6. A designed glycoprotein analogue of Gc-MAF exhibits native-like phagocytic activity.

    PubMed

    Bogani, Federica; McConnell, Elizabeth; Joshi, Lokesh; Chang, Yung; Ghirlanda, Giovanna

    2006-06-01

    Rational protein design has been successfully used to create mimics of natural proteins that retain native activity. In the present work, de novo protein engineering is explored to develop a mini-protein analogue of Gc-MAF, a glycoprotein involved in the immune system activation that has shown anticancer activity in mice. Gc-MAF is derived in vivo from vitamin D binding protein (VDBP) via enzymatic processing of its glycosaccharide to leave a single GalNAc residue located on an exposed loop. We used molecular modeling tools in conjunction with structural analysis to splice the glycosylated loop onto a stable three-helix bundle (alpha3W, PDB entry 1LQ7). The resulting 69-residue model peptide, MM1, has been successfully synthesized by solid-phase synthesis both in the aglycosylated and the glycosylated (GalNAc-MM1) form. Circular dichroism spectroscopy confirmed the expected alpha-helical secondary structure. The thermodynamic stability as evaluated from chemical and thermal denaturation is comparable with that of the scaffold protein, alpha3W, indicating that the insertion of the exogenous loop of Gc-MAF did not significantly perturb the overall structure. GalNAc-MM1 retains the macrophage stimulation activity of natural Gc-MAF; in vitro tests show an identical enhancement of Fc-receptor-mediated phagocytosis in primary macrophages. GalNAc-MM1 provides a framework for the development of mutants with increased activity that could be used in place of Gc-MAF as an immunomodulatory agent in therapy. PMID:16734450

  7. Antidiabetic activity of 3-hydroxyflavone analogues in high fructose fed insulin resistant rats

    PubMed Central

    Nayak, Yogendra; Venkatachalam, H.; Daroji, Vijay Kumar; Mathew, Geetha; Jayashree, B.S.; Unnikrishnan, M.K.

    2014-01-01

    Synthetic 3-hydroxyflavone analogues (JY-1, JY-2, JY-3, JY-4), were tested for antidiabetic activity in high-fructose-diet-fed (66 %, for 6 weeks) insulin-resistant Wistar rats (FD-fed rats). The fasting blood glucose, insulin, creatinine and AGEs were decreased to near normal upon treatment with test compounds. Insulin resistance markers such as HOMA-IR, K-ITT, plasma triglycerides, lipids, endogenous antioxidant defense and glycogen were restored in FD-fed rats after treatment with 3-hydroxyflavones. It is known that insulin resistance is partly because of oxidative stress and hence antioxidant activity was determined. They exhibited significant in vitro DPPH and ABTS radical scavenging activity (IC50: 10.66-66.63 µM). Test compounds inhibited ROS and NO production in RAW 264.7 cells (IC50: 10.39–42.63 µM) and they were found as potent as quercetin. Further, the test compounds inhibited lipid peroxidation at low concentrations (IC50: 99.61-217.47 µM). All test compounds at concentrations 100-200 µM protected calf thymus DNA-damage by Fenton reaction. In addition, test compounds inhibited protein glycation in different in vitro antiglycation assays. JY-2 showed maximum potency in all the stages of glycation which was comparable to the standard quercetin and aminoguanidine. Test compounds also enhanced the glucose uptake by L6 myotubes at an EC50 much lower than that of quercetin. Thus the synthetic 3-hydroxyflavones were found to have good antidiabetic activity by pleotropic and multimodal suppression of insulin resistance and enhancement of glucose uptake by skeletal muscles. These compounds are non-toxic at the doses tested. Further, the combined antioxidant and antiglycation activities of these molecules have complementary benefits in management of diabetes. PMID:26417321

  8. Synthesis, antimicrobial and anti-biofilm activities of novel Schiff base analogues derived from methyl-12-aminooctadec-9-enoate.

    PubMed

    Mohini, Y; Prasad, R B N; Karuna, M S L; Poornachandra, Y; Ganesh Kumar, C

    2014-11-15

    A novel library of Schiff base analogues (5a-q) were synthesized by the condensation of methyl-12-aminooctadec-9-enoate and different substituted aromatic aldehydes. The synthesized compounds were thoroughly characterized by spectroscopic techniques (FT-IR, (1)H NMR, (13)C NMR, ESI-MS and HRMS). The Schiff base analogues with different substitutions were screened for in vitro antibacterial activity against 7 different bacterial strains. Among these, the compounds with electron withdrawing substituent, namely chlorine (5a) and electron donating substituents, namely hydroxy (5 n) and methoxy (5 o), were found to exhibit excellent to good antimicrobial activities (MIC value 9-18 μM) against Staphylococcus aureus MTCC 96, Staphylococcus aureus MLS-16 MTCC 2940 and Bacillus subtilis MTCC 121. The products were also screened for anti-biofilm and MBC (Minimum Bactericidal Concentration) activities which exhibited promising activities.

  9. Fluorine-containing quinazolines and their oxa and thia analogues: Synthesis and biological activities

    NASA Astrophysics Data System (ADS)

    Nosova, Emiliya V.; Lipunova, Galina N.; Charushin, Valery N.

    2009-05-01

    Convenient methods for the synthesis of fluorine-containing quinazolines and their oxa and thia analogues are considered. Data on the prospects for using these compounds in medicine are given. Bibliography — 129 references.

  10. Fluorine-containing quinazolines and their oxa and thia analogues: synthesis and biological activities

    NASA Astrophysics Data System (ADS)

    Nosova, Emiliya V.; Lipunova, Galina N.; Charushin, Valery N.

    2009-05-01

    Convenient methods for the synthesis of fluorine-containing quinazolines and their oxa and thia analogues are considered. Data on the prospects for using these compounds in medicine are given. Bibliography — 129 references.

  11. Cell cycle effect on the activity of deoxynucleoside analogue metabolising enzymes

    SciTech Connect

    Fyrberg, Anna; Albertioni, Freidoun; Lotfi, Kourosh . E-mail: koulo@imv.liu.se

    2007-06-15

    Deoxynucleoside analogues (dNAs) are cytotoxic towards both replicating and indolent malignancies. The impact of fluctuations in the metabolism of dNAs in relation to cell cycle could have strong implications regarding the activity of dNAs. Deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK) are important enzymes for phosphorylation/activation of dNAs. These drugs can be dephosphorylated/deactivated by 5'-nucleotidases (5'-NTs) and elevated activities of 5'-NTs and decreased dCK and/or dGK activities represent resistance mechanisms towards dNAs. The activities of dCK, dGK, and three 5'-NTs were investigated in four human leukemic cell lines in relationship to cell cycle progression and cytotoxicity of dNAs. Synchronization of cell cultures to arrest in G0/G1 by serum-deprivation was performed followed by serum-supplementation for cell cycle progression. The activities of dCK and dGK increased up to 3-fold in CEM, HL60, and MOLT-4 cells as they started to proliferate, while the activity of cytosolic nucleotidase I was reduced in proliferating cells. CEM, HL60, and MOLT-4 cells were also more sensitive to cladribine, cytarabine, 9-{beta}-D-arabinofuranosylguanine and clofarabine than K562 cells which demonstrated lower levels and less alteration of these enzymes and were least susceptible to the cytotoxic effects of most dNAs. The results suggest that, in the cell lines studied, the proliferation process is associated with a general shift in the direction of activation of dNAs by inducing activities of dCK/dGK and reducing the activity of cN-I which is favourable for the cytotoxic effects of cladribine, cytarabine and, 9-{beta}-D-arabinofuranosylguanine. These results emphasize the importance of cellular proliferation and dNA metabolism by both phosphorylation and dephosphorylation for susceptibility to dNAs. It underscores the need to understand the mechanisms of action and resistance to dNAs in order to increase efficacy of dNAs treatment by new rational.

  12. Potentially active regions on Titan with Cassini/VIMS and Radar data: Terrestrial analogues.

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Le Mouélic, Stephane; Sotin, Christophe; Bratsolis, Emmanuel; Bampasidis, Georgios; Kyriakopoulos, Konstantinos; Moussas, Xenophon

    2010-05-01

    We present our study on Titan's geology in order to develop our current understanding of the satellite's active zones [1],[2]. The key aim is to study Titan's geology holistically, by means of internal activity and surface properties, in addition to terrestrial comparisons. We have applied the Principal Components Analysis (PCA) method in order to collect combined information of the seven infrared spectral windows, using the Cassini Mission Visual and Infrared Mapping Spectrometer (VIMS) data. The study areas for the moment are Tui Regio (located at 20°S, 130°W) and Hotei Regio (located at 26°S, 78°W). The main goal is to identify the composition as well as the alterations of the components that compose the possible calderas and lava flows [3], by using the principal components of the PCA method. Principal component analysis (PCA) is recommended, as our primary concern is to determine the minimum number of factors that will account for the maximum variance in the data in use in this particular multivariate analysis. Moreover, Cassini/Radar images have been processed [4] in order to study morphologically the active zones within the areas of Tui and Hotei Regio and to identify any analogues with terrestrial features. Both VIMS and Radar data [5] have provided significant information regarding the geology of the two areas, which should enable us to determine a possible internal activity as well as to identify superficial geologic structures. References [1] Nelson, R. M. (2009) Icarus 199, 429-441. [2] Solomonidou, A. (2009) European Planetary Science Congress Vol. 4, EPSC2009-710. [3] Sotin, C. (2005) Nature, Vol 435. [4] Bratsolis, E. & Sigelle, M. (2003) IEEE Transactions on Geoscience and Remote Sensing, 41, pp. 2890-2899. [5] Le Mouélic, S. (2008) Journal of Geophysical Research, Volume 113, Issue E4.

  13. Structure-dependent charge density as a determinant of antimicrobial activity of peptide analogues of defensin.

    PubMed

    Bai, Yang; Liu, Shouping; Jiang, Ping; Zhou, Lei; Li, Jing; Tang, Charles; Verma, Chandra; Mu, Yuguang; Beuerman, Roger W; Pervushin, Konstantin

    2009-08-01

    Defensins are small (3-5 kDa) cysteine-rich cationic proteins found in both vertebrates and invertebrates constituting the front line of host innate immunity. Despite intensive research, bactericidal and cytotoxic mechanisms of defensins are still largely unknown. Moreover, we recently demonstrated that small peptides derived from defensins are even more potent bactericidal agents with less toxicity toward host cells. In this paper, structures of three C-terminal (R36-K45) analogues of human beta-defensin-3 were studied by 1H NMR spectroscopy and extensive molecular dynamics simulations. Because of indications that these peptides might target the inner bacterial membrane, they were reconstituted in dodecylphosphocholine or dodecylphosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] mixed micelles, and lipid bicelles mimicking the phospholipid-constituted bilayer membrane of mammalian and bacterial cells. The results show that the binding affinity and partitioning into the lipid phase and the ability to dimerize and accrete well-defined structures upon interactions with lipid membranes contribute to compactization of positive charges within peptide oligomers. The peptide charge density, mediated by corresponding three-dimensional structures, was found to directly correlate with the antimicrobial activity. These novel observations may provide a new rationale for the design of improved antimicrobial agents.

  14. Metabotropic glutamate receptor 3 activation is required for long-term depression in medial prefrontal cortex and fear extinction.

    PubMed

    Walker, Adam G; Wenthur, Cody J; Xiang, Zixiu; Rook, Jerri M; Emmitte, Kyle A; Niswender, Colleen M; Lindsley, Craig W; Conn, P Jeffrey

    2015-01-27

    Clinical studies have revealed that genetic variations in metabotropic glutamate receptor 3 (mGlu3) affect performance on cognitive tasks dependent upon the prefrontal cortex (PFC) and may be linked to psychiatric conditions such as schizophrenia, bipolar disorder, and addiction. We have performed a series of studies aimed at understanding how mGlu3 influences PFC function and cognitive behaviors. In the present study, we found that activation of mGlu3 can induce long-term depression in the mouse medial PFC (mPFC) in vitro. Furthermore, in vivo administration of a selective mGlu3 negative allosteric modulator impaired learning in the mPFC-dependent fear extinction task. The results of these studies implicate mGlu3 as a major regulator of PFC function and cognition. Additionally, potentiators of mGlu3 may be useful in alleviating prefrontal impairments associated with several CNS disorders. PMID:25583490

  15. Metabotropic glutamate receptor 3 activation is required for long-term depression in medial prefrontal cortex and fear extinction

    PubMed Central

    Walker, Adam G.; Wenthur, Cody J.; Xiang, Zixiu; Rook, Jerri M.; Emmitte, Kyle A.; Niswender, Colleen M.; Lindsley, Craig W.; Conn, P. Jeffrey

    2015-01-01

    Clinical studies have revealed that genetic variations in metabotropic glutamate receptor 3 (mGlu3) affect performance on cognitive tasks dependent upon the prefrontal cortex (PFC) and may be linked to psychiatric conditions such as schizophrenia, bipolar disorder, and addiction. We have performed a series of studies aimed at understanding how mGlu3 influences PFC function and cognitive behaviors. In the present study, we found that activation of mGlu3 can induce long-term depression in the mouse medial PFC (mPFC) in vitro. Furthermore, in vivo administration of a selective mGlu3 negative allosteric modulator impaired learning in the mPFC-dependent fear extinction task. The results of these studies implicate mGlu3 as a major regulator of PFC function and cognition. Additionally, potentiators of mGlu3 may be useful in alleviating prefrontal impairments associated with several CNS disorders. PMID:25583490

  16. Extracellular cellobiose lipid from yeast and their analogues: structures and fungicidal activities.

    PubMed

    Kulakovskaya, Tatyana; Shashkov, Alexander; Kulakovskaya, Ekaterina; Golubev, Wladyslav; Zinin, Alexander; Tsvetkov, Yury; Grachev, Alexey; Nifantiev, Nikolay

    2009-01-01

    Basidiomycetous yeasts Cryptococcus humicola and Pseudozyma fusiformata secrete cellobiose lipids into the culture broth. In the case of Cr. humicola, 16-(tetra-O-acetyl-beta-cellobiosyloxy)-2-hydroxyhexadecanoic acid was defined as major product and 16-(tetra-O-acetyl-beta-cellobiosyloxy)-2,15-dihydrohexadecanoic acid was defined as minor product, while Ps. fusiformata secreted mainly 16-[6-O-acetyl-2'-O-(3-hydroxyhexanoyl)-beta-cellobiosyloxy)-2,15-dihydroxyhexadecanoic acid. These compounds exhibit similar fungicidal activities against different yeasts including pathogenic Cryptococcus and Candida species. The cells of Filobasidiella neoformans causing systemic cryptococcosis completely died after 30-min incubation with 0.02 mg mL(-1) of cellobiose lipids. The same effect on ascomycetous yeast, including pathogenic Candida species, is achieved at 0.1-0.3 mg mL(-1) of cellobiose lipids depending on the test culture used. Cellobiose lipid of Ps. fusiformata inhibits the growth of phytopathogenic fungi Sclerotinia sclerotiorum and Phomopsis helianthi more efficiently than cellobiose lipids from Cr. humicola. Fully O-deacylated analogue, namely 16-(beta-cellobiosyloxy)-2-hydroxyhexadecanoic acid, and totally synthetic compound, 16-(beta-cellobiosyloxy)-hexadecanoic acid, do not inhibit the growth of F. neoformans and Saccharomyces cerevisiae, while 16-(beta-cellobiosyloxy)-2,15-dihydroxyhexadecanoic acid inhibits the growth of both test cultures but at higher concentrations than cellobiose lipids of Cr. humicola and Ps. fusiformata. The amide of 16-(beta-cellobiosyloxy)-2,15-dihydroxyhexadecanoic acid possessed no fungicide activity. Thus, the structures of both the carbohydrate part and fatty acid aglycon moiety are important for the fungicidal activity of cellobiose lipids. PMID:19202311

  17. Fluvoxamine increased glutamate release by activating both 5-HT(3) and sigma-1 receptors in prelimbic cortex of chronic restraint stress C57BL/6 mice.

    PubMed

    Fu, Yingmei; Yu, Shunying; Guo, Xiaoyun; Li, Xia; Li, Ting; Li, Huafang; Dong, Yi

    2012-04-01

    Emerging evidence from therapeutic trials in humans and animal models suggests that in the treatment of depression, antidepressants play a role by targeting the glutamatergic system. Fluvoxamine is one of the widely used SSRIs which has been considered to target monoamine neurotransmitter reuptake mechanisms. However, whether fluvoxamine has an effect on the glutamate release is still unclear. The present experiment studied the effect of fluvoxamine on presynaptic glutamate release in prelimbic cortex, both in control C57BL/6 mice and chronic restraint stress C57BL/6 mice, and further investigated the mechanism underlying this effect by using patch clamp, on-line fluorimetry, pharmacological approaches combined with other techniques. The results showed that fluvoxamine increased the glutamate release in the depression model mice but it had no effect on the glutamate release in the control mice. The mechanism underlying these effects in depression model mice was that, fluvoxamine firstly activated presynaptic 5-HT(3) receptors, which transiently increased the Ca(2+) concentration. The increase of Ca(2+) concentration via 5-HT(3) receptors caused the activation of sigma-1 receptors, which were activated by fluvoxamine. The activation of sigma-1 receptors increased the intrasynaptosomal Ca(2+) concentration significantly through the outflow of endoplasmic reticulum calcium and finally activated PKC. These results suggested that fluvoxamine may have a selective effect and different mechanism based on the condition of animal. PMID:22306004

  18. Curcumin attenuates glutamate neurotoxicity in the hippocampus by suppression of ER stress-associated TXNIP/NLRP3 inflammasome activation in a manner dependent on AMPK.

    PubMed

    Li, Ying; Li, Jia; Li, Shanshan; Li, Yi; Wang, Xiangxiang; Liu, Baolin; Fu, Qiang; Ma, Shiping

    2015-07-01

    Curcumin is a natural polyphenolic compound in Curcuma longa with beneficial effects on neuronal protection. This study aims to investigate the action of curcumin in the hippocampus subjected to glutamate neurotoxicity. Glutamate stimulation induced reactive oxygen species (ROS), endoplasmic reticulum stress (ER stress) and TXNIP/NLRP3 inflammasome activation, leading to damage in the hippocampus. Curcumin treatment in the hippocampus or SH-SY5Y cells inhibited IRE1α and PERK phosphorylation with suppression of intracellular ROS production. Curcumin increased AMPK activity and knockdown of AMPKα with specific siRNA abrogated its inhibitory effects on IRE1α and PERK phosphorylation, indicating that AMPK activity was essential for the suppression of ER stress. As a result, curcumin reduced TXNIP expression and inhibited NLRP3 inflammasome activation by downregulation of NLRP3 and cleaved caspase-1 induction, and thus reduced IL-1β secretion. Specific fluorescent probe and flow cytometry analysis showed that curcumin prevented mitochondrial malfunction and protected cell survival from glutamate neurotoxicity. Moreover, oral administration of curcumin reduced brain infarct volume and attenuated neuronal damage in rats subjected to middle cerebral artery occlusion. Immunohistochemistry showed that curcumin inhibited p-IRE1α, p-PERK and NLRP3 expression in hippocampus CA1 region. Together, these results showed that curcumin attenuated glutamate neurotoxicity by inhibiting ER stress-associated TXNIP/NLRP3 inflammasome activation via the regulation of AMPK, and thereby protected the hippocampus from ischemic insult. PMID:25791922

  19. Biofunctional constituent isolated from Citrullus colocynthis fruits and structure-activity relationships of its analogues show acaricidal and insecticidal efficacy.

    PubMed

    Jeon, Ju-Hyun; Lee, Hoi-Seon

    2014-08-27

    The acaricidal and insecticidal potential of the active constituent isolated from Citrullus colocynthis fruits and its structurally related analogues was evaluated by performing leaf disk, contact toxicity, and fumigant toxicity bioassays against Tetranychus urticae, Sitophilus oryzae, and Sitophilus zeamais adults. The active constituent of C. colocynthis fruits was isolated by chromatographic techniques and was identified as 4-methylquinoline on the basis of spectroscopic analyses. To investigate the structure-activity relationships, 4-methylquinoline and its structural analogues were tested against mites and two insect pests. On the basis of the LC50 values, 7,8-benzoquinoline was the most effective against T. urticae. Quinoline, 8-hydroxyquinoline, 2-methylquinoline, 4-methylquinoline, 6-methylquinoline, 8-methylquinoline, and 7,8-benzoquinoline showed high insecticidal activities against S. oryzae and S. zeamais regardless of the application method. These results indicate that introduction of a functional group into the quinoline skeleton and changing the position of the group have an important influence on the acaricidal and insecticidal activities. Furthermore, 4-methylquinoline isolated from C. colocynthis fruits, along with its structural analogues, could be effective natural pesticides for managing spider mites and stored grain weevils.

  20. Biofunctional constituent isolated from Citrullus colocynthis fruits and structure-activity relationships of its analogues show acaricidal and insecticidal efficacy.

    PubMed

    Jeon, Ju-Hyun; Lee, Hoi-Seon

    2014-08-27

    The acaricidal and insecticidal potential of the active constituent isolated from Citrullus colocynthis fruits and its structurally related analogues was evaluated by performing leaf disk, contact toxicity, and fumigant toxicity bioassays against Tetranychus urticae, Sitophilus oryzae, and Sitophilus zeamais adults. The active constituent of C. colocynthis fruits was isolated by chromatographic techniques and was identified as 4-methylquinoline on the basis of spectroscopic analyses. To investigate the structure-activity relationships, 4-methylquinoline and its structural analogues were tested against mites and two insect pests. On the basis of the LC50 values, 7,8-benzoquinoline was the most effective against T. urticae. Quinoline, 8-hydroxyquinoline, 2-methylquinoline, 4-methylquinoline, 6-methylquinoline, 8-methylquinoline, and 7,8-benzoquinoline showed high insecticidal activities against S. oryzae and S. zeamais regardless of the application method. These results indicate that introduction of a functional group into the quinoline skeleton and changing the position of the group have an important influence on the acaricidal and insecticidal activities. Furthermore, 4-methylquinoline isolated from C. colocynthis fruits, along with its structural analogues, could be effective natural pesticides for managing spider mites and stored grain weevils. PMID:25110971

  1. Glutamate Limitation, BvgAS Activation, and (p)ppGpp Regulate the Expression of the Bordetella pertussis Type 3 Secretion System

    PubMed Central

    Kamachi, Kazunari; Yonezawa, Hideo; Fukutomi, Toshiyuki; Kawakami, Hayato; Kamiya, Shigeru

    2015-01-01

    ABSTRACT Bordetella pertussis is a bacterium that is considered to be highly adapted to humans, and it has not been isolated from the environment. As this bacterium does not utilize sugars, the abundant supply of glutamate in Stainer Scholte (SS) medium enables B. pertussis to grow efficiently in liquid culture in vitro, and as such, SS medium is a popular choice for laboratory experiments. However, the concentration of glutamate in the in vivo niche of B. pertussis is quite low. We investigated the bacterial response to low concentrations of glutamate to elucidate bacterial physiology via the expression of the type 3 secretion system (T3SS), and we discuss its relationship to the Bvg mode in which the two-component regulator of pathogenesis (BvgAS) is activated. Glutamate limitation induced the expression of both the T3SS apparatus and effector genes at the transcriptional level. (p)ppGpp, a modulator of the stringent response, was necessary for maximum expression of the T3SS genes. These observations indicate that the expression of the T3SS is managed by nutrient starvation. In addition, the autoaggregation ability was high in the absence of glutamate and no autoaggregation was observed in glutamate-replete medium. Taken together, glutamate-limited conditions in Bvg+ mode elicit the high expression of T3SS genes in B. pertussis and promotes its sessile form. IMPORTANCE Bordetella pertussis is a highly contagious pathogen that causes respiratory infectious disease. In spite of the increasing use of vaccination, the number of patients with pertussis is increasing. The proteins produced in vivo often are different from the protein profile under laboratory conditions; therefore, the development of conditions reflecting the host environment is important to understand native bacterial behavior. In the present study, we examined the effect of glutamate limitation, as its concentration in vivo is much lower than that in the culture medium currently used for B. pertussis

  2. Structure-activity studies on the anti-proliferation activity of ajoene analogues in WHCO1 oesophageal cancer cells.

    PubMed

    Kaschula, Catherine H; Hunter, Roger; Stellenboom, Nashia; Caira, Mino R; Winks, Susan; Ogunleye, Thozama; Richards, Philip; Cotton, Jonathan; Zilbeyaz, Kani; Wang, Yabing; Siyo, Vuyolwethu; Ngarande, Ellen; Parker, M Iqbal

    2012-04-01

    The organosulfur compound ajoene derived from the rearrangement of allicin found in crushed garlic can inhibit the proliferation of tumour cells by inducing G(2)/M cell cycle arrest and apoptosis. We report on the application of a concise four-step synthesis (Hunter et al., 2008 [1]) that allows access to ajoene analogues with the end allyl groups substituted. A library of twelve such derivatives tested for their anti-proliferation activity against WHCO1 oesophageal cancer cells has identified a derivative containing p-methoxybenzyl (PMB)-substituted end groups that is twelve times more active than Z-ajoene, with an IC(50) of 2.1μM (Kaschula et al., 2011 [2]). Structure-activity studies involving modification of the sulfoxide and vinyl disulfide groups of this lead have revealed that the disulfide is the ajoene pharmacophore responsible for inhibiting WHCO1 cell growth, inducing G(2)/M cell cycle arrest and apoptosis by caspase-3 activation, and that the vinyl group serves to enhance the anti-proliferation activity a further eightfold. Reaction of the lead with cysteine in refluxing THF as a model reaction for ajoene's mechanism of action based on a thiol/disulfide exchange reveals that the allylic sulfur of the vinyl disulfide is the site of thiol attack in the exchange. PMID:22381354

  3. Structure-activity studies on the anti-proliferation activity of ajoene analogues in WHCO1 oesophageal cancer cells.

    PubMed

    Kaschula, Catherine H; Hunter, Roger; Stellenboom, Nashia; Caira, Mino R; Winks, Susan; Ogunleye, Thozama; Richards, Philip; Cotton, Jonathan; Zilbeyaz, Kani; Wang, Yabing; Siyo, Vuyolwethu; Ngarande, Ellen; Parker, M Iqbal

    2012-04-01

    The organosulfur compound ajoene derived from the rearrangement of allicin found in crushed garlic can inhibit the proliferation of tumour cells by inducing G(2)/M cell cycle arrest and apoptosis. We report on the application of a concise four-step synthesis (Hunter et al., 2008 [1]) that allows access to ajoene analogues with the end allyl groups substituted. A library of twelve such derivatives tested for their anti-proliferation activity against WHCO1 oesophageal cancer cells has identified a derivative containing p-methoxybenzyl (PMB)-substituted end groups that is twelve times more active than Z-ajoene, with an IC(50) of 2.1μM (Kaschula et al., 2011 [2]). Structure-activity studies involving modification of the sulfoxide and vinyl disulfide groups of this lead have revealed that the disulfide is the ajoene pharmacophore responsible for inhibiting WHCO1 cell growth, inducing G(2)/M cell cycle arrest and apoptosis by caspase-3 activation, and that the vinyl group serves to enhance the anti-proliferation activity a further eightfold. Reaction of the lead with cysteine in refluxing THF as a model reaction for ajoene's mechanism of action based on a thiol/disulfide exchange reveals that the allylic sulfur of the vinyl disulfide is the site of thiol attack in the exchange.

  4. Tissue-type plasminogen activator-plasmin-BDNF modulate glutamate-induced phase-shifts of the mouse suprachiasmatic circadian clock in vitro.

    PubMed

    Mou, Xiang; Peterson, Cynthia B; Prosser, Rebecca A

    2009-10-01

    The mammalian circadian clock in the suprachiasmatic nucleus (SCN) maintains environmental synchrony through light signals transmitted by glutamate released from retinal ganglion terminals. Brain-derived neurotrophic factor (BDNF) is required for light/glutamate to reset the clock. In the hippocampus, BDNF is activated by the extracellular protease, plasmin, which is produced from plasminogen by tissue-type plasminogen activator (tPA). We provide data showing expression of proteins from the plasminogen activation cascade in the SCN and their involvement in circadian clock phase-resetting. Early night glutamate application to SCN-containing brain slices resets the circadian clock. Plasminogen activator inhibitor-1 (PAI-1) blocked these shifts in slices from wild-type mice but not mice lacking its stabilizing protein, vitronectin (VN). Plasmin, but not plasminogen, prevented inhibition by PAI-1. Both plasmin and active BDNF reversed alpha(2)-antiplasmin inhibition of glutamate-induced shifts. alpha(2)-Antiplasmin decreased the conversion of inactive to active BDNF in the SCN. Finally, both tPA and BDNF allowed daytime glutamate-induced phase-resetting. Together, these data are the first to demonstrate expression of these proteases in the SCN, their involvement in modulating photic phase-shifts, and their activation of BDNF in the SCN, a potential 'gating' mechanism for photic phase-resetting. These data also demonstrate a functional interaction between PAI-1 and VN in adult brain. Given the usual association of these proteins with the extracellular matrix, these data suggest new lines of investigation into the locations and processes modulating mammalian circadian clock phase-resetting.

  5. Functional magnetic resonance spectroscopy of glutamate in schizophrenia and major depressive disorder: anterior cingulate activity during a color-word Stroop task

    PubMed Central

    Taylor, Reggie; Neufeld, Richard W J; Schaefer, Betsy; Densmore, Maria; Rajakumar, Nagalingam; Osuch, Elizabeth A; Williamson, Peter C; Théberge, Jean

    2015-01-01

    Background: Glutamate abnormalities have been suggested to be associated with symptoms of schizophrenia. Using functional magnetic resonance spectroscopy (1H-fMRS), it is possible to monitor glutamate dynamically in the activated brain areas, which has yet to be reported in schizophrenia. It was hypothesized that subjects with schizophrenia would have weaker glutamatergic responses in the anterior cingulate to a color-word Stroop Task. AIMS: The aim of this study was to gain insight into the health of GLU neurotransmission and the GLU-GLN cycle in SZ using a 1H-fMRS protocol. Methods: Spectra were acquired from the anterior cingulate of 16 participants with schizophrenia, 16 healthy controls and 16 participants with major depressive disorder (MDD) while performing the Stroop task in a 7T magnetic resonance imaging scanner. 1H-fMRS spectra were acquired for 20 min in which there were three 4-min blocks of cross fixation interleaved with two 4-min blocks of the Stroop paradigm. Results: A repeated-measures analysis of variance revealed a main effect of time for glutamate concentrations of all groups (P<0.001). The healthy control group increased glutamate concentrations in the first run of the Stroop task (P=0.006) followed by a decrease in the recovery period (P=0.007). Neither the schizophrenia (P=0.107) nor MDD (P=0.081) groups had significant glutamate changes in the first run of the task, while the schizophrenia group had a significant increase in glutamine (P=0.005). The MDD group decreased glutamate concentrations in the second run of the task (P=0.003), as did all the groups combined (P=0.003). Conclusions: 1H-fMRS data were successfully acquired from psychiatric subjects with schizophrenia and mood disorder using a cognitive paradigm for the first time. Future study designs should further elucidate the glutamatergic response to functional activation in schizophrenia. PMID:27336037

  6. The peroxisome proliferator activated receptor gamma agonist pioglitazone increases functional expression of the glutamate transporter excitatory amino acid transporter 2 (EAAT2) in human glioblastoma cells

    PubMed Central

    Ching, Jared; Amiridis, Stephanie; Stylli, Stanley S.; Bjorksten, Andrew R.; Kountouri, Nicole; Zheng, Thomas; Paradiso, Lucy; Luwor, Rodney B.; Morokoff, Andrew P.; O'Brien, Terence J.; Kaye, Andrew H.

    2015-01-01

    Glioma cells release glutamate through expression of system xc−, which exchanges intracellular glutamate for extracellular cysteine. Lack of the excitatory amino acid transporter 2 (EAAT2) expression maintains high extracellular glutamate levels in the glioma microenvironment, causing excitotoxicity to surrounding parenchyma. Not only does this contribute to the survival and proliferation of glioma cells, but is involved in the pathophysiology of tumour-associated epilepsy (TAE). We investigated the role of the peroxisome proliferator activated receptor gamma (PPARγ) agonist pioglitazone in modulating EAAT2 expression in glioma cells. We found that EAAT2 expression was increased in a dose dependent manner in both U87MG and U251MG glioma cells. Extracellular glutamate levels were reduced with the addition of pioglitazone, where statistical significance was reached in both U87MG and U251MG cells at a concentration of ≥ 30 μM pioglitazone (p < 0.05). The PPARγ antagonist GW9662 inhibited the effect of pioglitazone on extracellular glutamate levels, indicating PPARγ dependence. In addition, pioglitazone significantly reduced cell viability of U87MG and U251MG cells at ≥ 30 μM and 100 μM (p < 0.05) respectively. GW9662 also significantly reduced viability of U87MG and U251MG cells with 10 μM and 30 μM (p < 0.05) respectively. The effect on viability was partially dependent on PPARγ activation in U87MG cells but not U251MG cells, whereby PPARγ blockade with GW9662 had a synergistic effect. We conclude that PPARγ agonists may be therapeutically beneficial in the treatment of gliomas and furthermore suggest a novel role for these agents in the treatment of tumour associated seizures through the reduction in extracellular glutamate. PMID:26046374

  7. Mammalian folylpoly-. gamma. -glutamate synthetase. 2. Substrate specificity and kinetic properties

    SciTech Connect

    Cichowicz, D.J.; Shane, B.

    1987-01-27

    The specificity of hog liver folylpolyglutamate synthetase for folate substrates and for nucleotide and L-(/sup 14/C)glutamate substrates and analogues has been investigated. The kinetic mechanism, determined by using aminopterin as the folate substrate, is ordered Ter-Ter with MgATP binding first, folate second, and glutamate last. This mechanism precludes the sequential addition of glutamate moieties to enzyme-bound folate. Folate, dihydrofolate, and tetrahydrofolate possess the optimal configurations for catalysis while 5- and 10-position substitutions of the folate molecule impair catalysis. k/sub cat/ values decrease with increasing glutamate chain length, and the rate of decrease varies depending on the state of reduction and substitution of the folate molecule. Folate binding, as assessed by on rates, is slow. Dihydrofolate exhibits the fastest rate, and the rates are slightly reduced for tetrahydrofolate and 10-formyltetrahydrofolate and greatly reduced for 5-methyltetrahydrofolate and folic acid. Tetrahydrofolate polyglutamates are the only long glutamate chain length folates with detectable substrate activity. The specificity of the L-glutamate binding site is very narrow. L-Homocysteate and 4-threo-fluoroglutamate are alternate substrates and act as chain termination inhibitors in that their addition to the folate molecule prevents or severely retards the further addition of glutamate moieties. The K/sub m/ for glutamate is dependent on the folate substrate used. MgATP is the preferred nucleotide substrate, and ..beta..,..gamma..-methylene-ATP, ..beta..,..gamma..-imido-ATP, adenosine 5'-O-(3-thiotriphosphate), P/sup 1/,P/sup 5/-di(adenosine-5') pentaphosphate, and free ATP/sup 4 -/ are potent inhibitors of the reaction.

  8. Structure-Activity Studies of Brassinosteroids and the Search for Novel Analogues and Mimetics with Improved Bioactivity.

    PubMed

    Back, Thomas G.; Pharis, Richard P.

    2003-12-01

    A number of novel brassinosteroid analogues were synthesized and subjected to the rice leaf lamina inclination bioassay. Modified B-ring analogues included lactam, thiolactone, cyclic ether, ketone, hydroxyl, and exocyclic methylene derivatives of brassinolide. Those derivatives containing polar functional groups retained considerable bioactivity, whereas the exocyclic methylene compounds were devoid of activity. Analogues containing normal alkyl and cycloalkyl substituents at C-24 (in place of the isopropyl group of brassinolide) showed an inverse relationship between activity and chain length or ring size, respectively. The corresponding cyclopropyl and cyclobutyl derivatives were significantly more active than brassinolide and appear to be the most potent brassinosteroids reported to date. When synergized with the auxin indole-3-acetic acid (IAA), their bioactivity can be further enhanced by 1-2 orders of magnitude. The cyclopropyl derivative, when coapplied with the auxin naphthaleneacetic acid, gave a significant increase in yield of wheat in a field trial. Certain 25- and 26-hydroxy derivatives are known metabolites of brassinosteroids. All of the C-25 stereoisomers of 25-hydroxy, 26-hydroxy, and 25,26-dihydroxy derivatives of brassinolide were prepared and shown to be much less active than brassinolide. This indicates that they are likely metabolic deactivation products of the parent phytohormone. A series of methyl ethers of brassinolide was synthesized to block deactivation by glucosylation of the free hydroxyl groups. The most significant finding was that the compound where three of the four hydroxyl groups (at C-3, C-22, and C-23) had been converted to methyl ethers retained substantial bioactivity. This type of modification could, in theory, allow brassinolide or 24-epibrassinolide to resist deactivation and thus offer greater persistence in field applications. A series of nonsteroidal mimetics of brassinolide was designed and synthesized. Two of the

  9. Exploring an active hydrothermal system - An analogue study from the Swiss Alps

    NASA Astrophysics Data System (ADS)

    Egli, Daniel; Herwegh, Marco; Berger, Alfons; Baron, Ludovic

    2016-04-01

    Understanding the detailed flow paths in hydrothermal reservoirs is crucial for successful exploration of naturally porous and permeable rock masses for energy production. However, due to the common inaccessibility of active hydrothermal systems of suitable depth, e.g. in the northern Alpine foreland of the European Alps, direct observations are normally impossible and the knowledge about such systems is still insufficient. For that reason, a known fault-bound hydrothermal system in the crystalline basement of the Aar Massif serves as an analogue for potential geothermal reservoirs in the deep crystalline subsurface of the northern Alpine foreland. During summer 2015, a 125 m hole has been drilled across this active hydrothermal zone on the Grimsel Pass for in-situ characterization of its structural, petrophysical, mechanical as well as geophysical parameters. With this information, this project aims at improving the knowledge of natural hydrothermal systems as a potentially exploitable energy source. The investigated system is characterized by a central breccia zone surrounded by different types of cataclasites and localized high strain zones. The surrounding includes different altered and deformed granitoid host rocks. In this study, we focus on the ductile and brittle deformation (shear zones, fractures, joints) that provides the main fluid pathways. Their spatial distribution around a central water-bearing breccia zone as well as their continuity and permeability provide constraints on the water flow paths in such structurally controlled hydrothermal systems. The aim will be the connection of detailed structural data with petrophysical parameters such as porosities and permeabilities. The drillcore shows the high variability of deformation structures and related fluid pathways at different scales (millimeter-decameter) demonstrating the urgent need for an improved understanding of the link between mechanical evolution, associated deformation structures as well

  10. Exhumed analogues of seismically active carbonate-bearing thrusts: fault architecture and deformation mechanisms

    NASA Astrophysics Data System (ADS)

    Tesei, T.; Collettini, C.; Viti, C.; Barchi, M. R.

    2012-12-01

    In May 2012 a M = 5.9 earthquake followed by a long aftershock sequence struck the Northern Italy. The sequence occurred at 4-10 km depth within the active front of Northern Apennines Prism and the major events nucleate within, or propagate through, a thick sequence of carbonates. In an inner sector of the Northern Apennines, ancient carbonate-bearing thrusts exposed at the surface, represent exhumed analogues of structures generating seismicity in the active front. Here we document fault architecture and deformation mechanisms of three regional carbonate bearing thrusts with displacement of several kilometers and exhumation in the range of 1-4 km. Fault zone structure and deformation mechanisms are controlled by the lithology of the faulted rocks. In layered limestones and marly-limestones the fault zone is up to 200 m thick and is characterized by intense pressure solution. In massive limestones the deformation generally occurs along thin and sharp slip planes that are in contact with fault portions affected by either cataclasis or pressure solution. SEM and TEM observations show that pressure solution surfaces, made of smectite lamellae, with time tend to form an interconnected network affected by frictional sliding. Sharp slipping planes along massive limestones show localization along Y shear planes that separate an extremely comminuted cataclasites from an almost undeformed protolith. The comparison of the three shear zones depicts a fault zone structure extremely heterogeneous as the result of protolith lithology, geometrical complexities and the presence of inherited structures. We observe the competition between brittle (cataclasis, distributed frictional sliding along phyllosilicates and extremely localized slip within carbonates) and pressure solution processes, that suggest a multi-mode of slip behaviour. Extreme localization along carbonate-bearing Y shear planes is our favorite fault zone feature representing past seismic ruptures along the studied

  11. Comparative structure-activity relationships of benztropine analogues at the dopamine transporter and histamine H(1) receptors.

    PubMed

    Kulkarni, Santosh S; Kopajtic, Theresa A; Katz, Jonathan L; Newman, Amy Hauck

    2006-06-01

    Benztropine (BZT) and its analogues inhibit dopamine uptake and bind with moderate to high affinity to the dopamine transporter (DAT). However, many of these compounds, in contrast to other monoamine uptake inhibitors, lack cocaine-like behavioral effects and fail to potentiate the effects of cocaine. The BZT analogues also exhibit varied binding affinities for muscarinic M(1) and histamine H(1) receptors. In this study, a comparative analysis was conducted of pharmacophoric features with respect to the activities of BZT analogues at the DAT and at the histamine H(1) receptor. The BZT analogues showed a wide range of histamine H(1) receptor (K(i)=16-37,600 nM) and DAT (K(i)=8.5-6370 nM) binding affinities. A stereoselective histamine H(1)-antagonist pharmacophore, using a five-point superimposition of classical antagonists on the template, cyproheptadine, was developed. A series of superimpositions and comparisons were performed with various analogues of BZT. In general, smaller substituents were well tolerated on the aromatic rings of the diphenyl methoxy group for both the DAT and H(1) receptor, however, for the H(1) receptor, substitution at only one of the aromatic rings was preferred. The substituents at the 2- and N-positions of the tropane ring were preferred for DAT, however, these groups seem to overlap receptor essential regions in the histamine H(1) receptor. Molecular models at the DAT and the histamine H(1) receptor provide further insight into the structural requirements for binding affinity and selectivity that can be implemented in future drug design.

  12. Amide-controlled, one-pot synthesis of tri-substituted purines generates structural diversity and analogues with trypanocidal activity.

    PubMed

    Pineda de las Infantas y Villatoro, Maria J; Unciti-Broceta, Juan D; Contreras-Montoya, Rafael; Garcia-Salcedo, Jose A; Gallo Mezo, Miguel A; Unciti-Broceta, Asier; Diaz-Mochon, Juan J

    2015-01-01

    A novel one-pot synthesis of tri-substituted purines and the discovery of purine analogues with trypanocidal activity are reported. The reaction is initiated by a metal-free oxidative coupling of primary alkoxides and diaminopyrimidines with Schiff base formation and subsequent annulation in the presence of large N,N-dimethylamides (e.g. N,N-dimethylpropanamide or larger). This synthetic route is in competition with a reaction previously-reported by our group, allowing the generation of a combinatorial library of tri-substituted purines by the simple modification of the amide and the alkoxide employed. Among the variety of structures generated, two purine analogues displayed trypanocidal activity against the protozoan parasite Trypanosoma brucei with IC50 < 5 μM, being each of those compounds obtained through each of the synthetic pathways.

  13. Synaptic activation of metabotropic glutamate receptors in the parallel fibre-Purkinje cell pathway in rat cerebellar slices.

    PubMed

    Batchelor, A M; Madge, D J; Garthwaite, J

    1994-12-01

    Glutamate, the major excitatory neurotransmitter in the central nervous system, acts through two broad classes of receptors: ion channel-linked (ionotropic) receptors, which include N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, and metabotropic receptors which couple via G-proteins to intracellular messenger cascades. Seven subtypes of mGluR are known to exist but their roles in synaptic physiology are poorly understood. In cerebellar Purkinje cells, application of the mGluR agonist, trans-1-aminocyclopentane-1,3-dicarboxylic acid, or the active enantiomer, 1S,3R-ACPD, results in a depolarization associated with an inward current and an elevation of intracellular Ca2+ (for review see Ref. 29). Moreover, using an extracellular (grease-gap) technique that monitors population responses, we have previously discovered that, in Purkinje cells of adult rat cerebellum, brief tetanic stimulation of the glutamatergic parallel fibre input gives rise to a slow depolarising synaptic potential that is resistant to ionotropic glutamate receptor blockers and to antagonists acting at GABA receptors. It was suggested that this novel potential is mediated by metabotropic receptors. The advent of antagonists for metabotropic receptors has allowed us to test this hypothesis. We find that the S-enantiomer of alpha-methyl-4-carboxyphenylglycine stereoselectively antagonizes the slow synaptic potential recorded using the grease-gap method. The results were confirmed by intracellular recording from Purkinje cells. To our knowledge this is the first direct evidence of an mGluR-mediated EPSP in intact brain tissue. PMID:7535396

  14. Structure-activity relationship of Garcinia xanthones analogues: Potent Hsp90 inhibitors with cytotoxicity and antiangiogenesis activity.

    PubMed

    Xu, Xiaoli; Wu, Yue; Hu, Mingyang; Li, Xiang; Gu, Congying; You, Qidong; Zhang, Xiaojin

    2016-10-01

    Hsp90 has long been recognized as an attractive and crucial molecular target for cancer therapy. Gambogic acid (GA), the main active compound of Gamboge hanburyi, has been reported as a natural inhibitor of Hsp90. Here, we present the structure-activity relationship of Garcinia xanthones analogues as Hsp90 inhibitors and identify that compound 25, with a simplified skeleton, had an improved inhibitory effect toward Hsp90. Compound 25 inhibited the ATPase activity of Hsp90 with an IC50 value of 3.68±0.18μM. It also exhibited potent antiproliferative activities in some solid tumor cells. In SK-BR-3 cells with high Hsp90 expression, compound 25 induced the degradation of Hsp90 client proteins including Akt and Erk1/2 without causing the heat shock response. Additionally, compound 25 inhibited angiogenesis in HUVEC cells through Hsp90 regulation of the HIF-1α pathway. These results demonstrate that compound 25 as an Hsp90 inhibitor with a new structure could be further studied for the development of tumor therapy. PMID:27527413

  15. Acetoxybenzhydrols as highly active and stable analogues of 1'S-1'-acetoxychavicol, a potent antiallergic principal from Alpinia galanga.

    PubMed

    Yasuhara, Tomohisa; Manse, Yoshiaki; Morimoto, Takayuki; Qilong, Wang; Matsuda, Hisashi; Yoshikawa, Masayuki; Muraoka, Osamu

    2009-06-01

    Through SAR studies on 1'S-1'-acetoxychavicol acetate (1) against Type I antiallergic activity by indexing release of beta-hexosaminidase, a marker of antigen-IgE-mediated degranulation in RBL-2H3 cells, more stable and potent analogue, 4-(methoxycarbonyloxyphenylmethyl)phenyl acetate (16), has been developed. The compound 16 also strongly inhibited the antigen-IgE-mediated TNF-alpha and IL-4 production.

  16. Glutamate and GABA activate different receptors and Cl(-) conductances in crab peptide-secretory neurons.

    PubMed

    Duan, S; Cooke, I M

    2000-01-01

    Responses to rapid application of glutamic acid (Glu) and gamma-aminobutyric acid (GABA), 0.01-3 mM, were recorded by whole-cell patch clamp of cultured crab (Cardisoma carnifex) X-organ neurons. Responses peaked within 200 ms. Both Glu and GABA currents had reversal potentials that followed the Nernst Cl(-) potential when [Cl(-)](i) was varied. A Boltzmann fit to the normalized, averaged dose-response curve for Glu indicated an EC(50) of 0.15 mM and a Hill coefficient of 1.05. Rapid (t(1/2) approximately 1 s) desensitization occurred during Glu but not GABA application that required >2 min for recovery. Desensitization was unaffected by concanavalin A or cyclothiazide. N-methyl-D-aspartate, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, quisqualate, and kainate (to 1 mM) were ineffective, nor were Glu responses influenced by glycine (1 microM) or Mg(2+) (0-26 mM). Glu effects were imitated by ibotenic acid (0.1 mM). The following support the conclusion that Glu and GABA act on different receptors: 1) responses sum; 2) desensitization to Glu or ibotenic acid did not diminish GABA responses; 3) the Cl(-)-channel blockers picrotoxin and niflumic acid (0.5 mM) inhibited Glu responses by approximately 90 and 80% but GABA responses by approximately 50 and 20%; and 4) polyvinylpyrrolydone-25 (2 mM in normal crab saline) eliminated Glu responses but left GABA responses unaltered. Thus crab secretory neurons have separate receptors responsive to Glu and to GABA, both probably ionotropic, and mediating Cl(-) conductance increases. In its responses and pharmacology, this crustacean Glu receptor resembles Cl(-)-permeable Glu receptors previously described in invertebrates and differs from cation-permeable Glu receptors of vertebrates and invertebrates.

  17. Enzymatic synthesis of theanine from glutamic acid γ-methyl ester and ethylamine by immobilized Escherichia coli cells with γ-glutamyltranspeptidase activity.

    PubMed

    Zhang, Fei; Zheng, Qing-Zhong; Jiao, Qing-Cai; Liu, Jun-Zhong; Zhao, Gen-Hai

    2010-11-01

    Theanine (γ-glutamylethylamide) is the main amino acid component in green tea. The demand for theanine in the food and pharmaceutical industries continues to increase because of its special flavour and multiple physiological effects. In this research, an improved method for enzymatic theanine synthesis is reported. An economical substrate, glutamic acid γ-methyl ester, was used in the synthesis catalyzed by immobilized Escherichia coli cells with γ-glutamyltranspeptidase (GGT) activity. The results show that GGT activity with glutamic acid γ-methyl ester as substrate was about 1.2-folds higher than that with glutamine as substrate. Reaction conditions were optimized by using 300 mmol/l glutamic acid γ-methyl ester, 3,000 mmol/l ethylamine, and 0.1 g/ml of immobilized GGT cells at pH 10 and 50°C. Under these conditions, the immobilized cells were continuously used ten times, yielding an average glutamic acid γ-methyl ester to theanine conversion rate of 69.3%. Bead activity did not change significantly the first six times they were used, and the average conversion rate during the first six instances was 87.2%. The immobilized cells exhibited favourable operational stability.

  18. Effect of chirality and lipophilicity in the functional activity of evodiamine and its analogues at TRPV1 channels

    PubMed Central

    De Petrocellis, Luciano; Schiano Moriello, Aniello; Fontana, Gabriele; Sacchetti, Alessandro; Passarella, Daniele; Appendino, Giovanni; Di Marzo, Vincenzo

    2014-01-01

    Background and Purpose Evodiamine, a racemic quinazolinocarboline alkaloid isolated from the traditional Chinese medicine Evodiae fructus, has been reported to act as an agonist of the transient receptor potential vanilloid type-1 (TRPV1) cation channel both in vitro and in vivo. Evodiamine is structurally different from all known TRPV1 activators, and has significant clinical potential as a thermogenic agent. Nevertheless, the molecular bases for its actions are still poorly understood. Experimental Approach To investigate the structure-activity relationships of evodiamine, the natural racemate was resolved, and a series of 23 synthetic analogues was prepared, using as the end point the intracellular Ca2+ elevation in HEK-293 cells stably overexpressing either the human or the rat recombinant TRPV1. Key Results S-(+) evodiamine was more efficacious and potent than R-(−) evodiamine, and a new potent lead (Evo30) was identified, more potent than the reference TRPV1 agonist, capsaicin. In general, potency and efficacy correlated with the lipophilicity of the analogues. Like other TRPV1 agonists, several synthetic analogues could efficiently desensitize TRPV1 to activation by capsaicin. Conclusions and Implications Evodiamine qualifies as structurally unique lead structure to develop new potent TRPV1 agonists/desensitizers. Linked Articles This article is part of a themed section on the pharmacology of TRP channels. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-10 PMID:23902373

  19. Polycationic gramicidin S analogues with both high antibiotic activity and very low hemolytic activity.

    PubMed

    Tamaki, Makoto; Harada, Takuji; Fujinuma, Kenta; Takanashi, Kazumasa; Shindo, Mitsuno; Kimura, Masahiro; Uchida, Yoshiki

    2012-01-01

    The substitution of each constituent amino acid residue of gramicidin S (GS), cyclo(-Val(1,1')-Orn(2,2')-Leu(3,3')-D-Phe(4,4')-Pro(5,5')-)(2) with Lys residue indicated that each side chain structure of the constituent amino acid residues affect largely the antibiotic activity and hemolytic activity of GS. Further, the substitution of D-Phe(4,4') and Pro(5,5') residues with basic amino acid residues as a Lys residue results the high antibiotic activity and the very low hemolytic activity. Thus, we have found novel positions on the scaffold of GS at D-Phe(4,4') and Pro(5,5') residues whose modification will significantly increase the therapeutic index.

  20. Synthesis, biological activities, and quantitative structure-activity relationship (QSAR) study of novel camptothecin analogues.

    PubMed

    Wu, Dan; Zhang, Shao-Yong; Liu, Ying-Qian; Wu, Xiao-Bing; Zhu, Gao-Xiang; Zhang, Yan; Wei, Wei; Liu, Huan-Xiang; Chen, An-Liang

    2015-05-13

    In continuation of our program aimed at the development of natural product-based pesticidal agents, three series of novel camptothecin derivatives were designed, synthesized, and evaluated for their biological activities against T. Cinnabarinus, B. brassicae, and B. xylophilus. All of the derivatives showed good-to-excellent activity against three insect species tested, with LC50 values ranging from 0.00761 to 0.35496 mmol/L. Remarkably, all of the compounds were more potent than CPT against T. Cinnabarinus, and compounds 4d and 4c displayed superior activity (LC50 0.00761 mmol/L and 0.00942 mmol/L, respectively) compared with CPT (LC50 0.19719 mmol/L) against T. Cinnabarinus. Based on the observed bioactivities, preliminary structure-activity relationship (SAR) correlations were also discussed. Furthermore, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model using comparative molecular field analysis (CoMFA) was built. The model gave statistically significant results with the cross-validated q2 values of 0.580 and correlation coefficient r2 of 0.991 and  of 0.993. The QSAR analysis indicated that the size of the substituents play an important in the activity of 7-modified camptothecin derivatives. These findings will pave the way for further design, structural optimization, and development of camptothecin-derived compounds as pesticidal agents.

  1. Synthesis and biological activity of a profluorescent analogue of coenzyme B12.

    PubMed Central

    Rosendahl, M S; Omann, G M; Leonard, N J

    1982-01-01

    We describe here the synthesis and chemical properties of linear(lin)-benzoadenosylcobalamin, a coenzyme B12 analogue that has a laterally extended nucleoside in the upper axial position. It is an effective competitive inhibitor of ribonucleotide reductase from Lactobacillus leichmannii. lin-Benzoadenosylcobalamin is nonfluorescent in solution but, on homolytic (light) or heterolytic (acid, cyanide) cleavage of the carbon-cobalt bond, forms fluorescent products. In addition, fluorescence is detectable on binding of the coenzyme analogue to ribonucleotide reductase, and the observed fluorescence polarization of the lin-benzoadenosyl moiety indicates that it is bound loosely to the enzyme when the coenzyme is partially dissociated. PMID:7048307

  2. Relative activities on and uptake by human blood platelets of 5-hydroxytryptamine and several analogues

    PubMed Central

    Born, G. V. R.; Juengjaroen, Kanchana; Michal, F.

    1972-01-01

    1. The specificity of platelet receptor sites for 5-HT uptake and for the rapid morphological change and aggregation was investigated with 5-hydroxy-tryptamine (5-HT) and seventeen analogues as well as with some antagonists of 5-HT. 2. The analogues, with the exception of 5-hydroxy-N'N'-dibutyltryptamine, caused the rapid morphological change in platelets. In concentrations below those needed to produce the agonistic action (viz. 0.05-2.0 μM), these analogues themselves inhibited competitively the shape change caused by 5-HT. 3. The velocity of change in shape caused by 5-HT was reduced in low Na media. 4. Ten analogues produced platelet aggregation; three of these, viz. 5-methoxy-α-methyltryptamine, 5-hydroxy-α-methyltryptamine and 5-hydroxy-N'N'-diisopropyltryptamine), were approximately equipotent with 5-HT. Six analogues did not induce platelet aggregation. 5. All the analogues which prevented the initial change in shape of platelets caused by 5-HT also inhibited its aggregating effect, apparently competitively with low Ki values (0.02-1.6 μM). 6. As with the inhibition of shape change, the inhibition of aggregation shows relatively low structural specificity of the receptor site. 7. Methysergide was a potent inhibitor of shape change and aggregation (Ki∼0.03 μM); imipramine was much less inhibitory (Ki∼5-10 μM). 8. Only one analogue (5-hydroxy-α-methyltryptamine) was taken up like 5-HT by platelets. All the other analogues inhibited the uptake of 5-HT by platelets (Ki=0.2-2.7 μM). 9. Methysergide was a weak inhibitor of 5-HT uptake (Ki∼125 μM) whereas imipramine was very effective (Ki∼0.3 μM). 10. Our results show that the initial change in shape of platelets is required for and precedes aggregation. The structural specificity of the platelet receptor concerned with shape change and aggregation caused by 5-HT appears low whereas the uptake mechanism is a highly specific one. The uptake probably proceeds through more than one step, the

  3. Chicken liver glutamate dehydrogenase (GDH) demonstrates a histone H3 specific protease (H3ase) activity in vitro.

    PubMed

    Purohit, Jogeswar S; Tomar, Raghuvir S; Panigrahi, Anil K; Pandey, Shashibhal M; Singh, Divya; Chaturvedi, Madan M

    2013-11-01

    Site-specific proteolysis of the N or C-terminus of histone tails has emerged as a novel form of irreversible post-translational modifications assigned to histones. Though there are many reports describing histone specific proteolysis, there are very few studies on purification of a histone specific protease. Here, we demonstrate a histone H3 specific protease (H3ase) activity in chicken liver nuclear extract. H3ase was purified to homogeneity and identified as glutamate dehydrogenase (GDH) by sequencing. A series of biochemical experiments further confirmed that the H3ase activity was due to GDH. The H3ase clipped histone H3 products were sequenced by N-terminal sequencing and the precise clipping sites of H3ase were mapped. H3ase activity was only specific to chicken liver as it was not demonstrated in other tissues like heart, muscle and brain of chicken. We assign a novel serine like protease activity to GDH which is specific to histone H3. PMID:23856561

  4. Estrogen Receptor β Activation Rapidly Modulates Male Sexual Motivation through the Transactivation of Metabotropic Glutamate Receptor 1a.

    PubMed

    Seredynski, Aurore L; Balthazart, Jacques; Ball, Gregory F; Cornil, Charlotte A

    2015-09-23

    In addition to the transcriptional activity of their liganded nuclear receptors, estrogens, such as estradiol (E2), modulate cell functions, and consequently physiology and behavior, within minutes through membrane-initiated events. The membrane-associated receptors (mERs) underlying the acute effects of estrogens on behavior have mostly been documented in females where active estrogens are thought to be of ovarian origin. We determined here, by acute intracerebroventricular injections of specific agonists and antagonists, the type(s) of mERs that modulate rapid effects of brain-derived estrogens on sexual motivation in male Japanese quail. Brain aromatase blockade acutely inhibited sexual motivation. Diarylpropionitrile (DPN), an estrogen receptor β (ERβ)-specific agonist, and to a lesser extent 17α-estradiol, possibly acting through ER-X, prevented this effect. In contrast, drugs targeting ERα (PPT and MPP), GPR30 (G1 and G15), and the Gq-mER (STX) did not affect sexual motivation. The mGluR1a antagonist LY367385 significantly inhibited sexual motivation but mGluR2/3 and mGluR5 antagonists were ineffective. LY367385 also blocked the behavioral restoration induced by E2 or DPN, providing functional evidence that ERβ interacts with metabotropic glutamate receptor 1a (mGluR1a) signaling to acutely regulate male sexual motivation. Together these results show that ERβ plays a key role in sexual behavior regulation and the recently uncovered cooperation between mERs and mGluRs is functional in males where it mediates the acute effects of estrogens produced centrally in response to social stimuli. The presence of an ER-mGluR interaction in birds suggests that this mechanism emerged relatively early in vertebrate history and is well conserved. Significance statement: The membrane-associated receptors underlying the acute effects of estrogens on behavior have mostly been documented in females, where active estrogens are thought to be of ovarian origin. Using acute

  5. Glutamate regulates Oct-2 DNA-binding activity through alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors in cultured chick Bergmann glia cells.

    PubMed

    Méndez, J Alfredo; López-Bayghen, Esther; Rojas, Fausto; Hernández, María Elena; Ortega, Arturo

    2004-02-01

    Ionotropic glutamate receptors in cerebellar Bergmann glial cells are linked to transcriptional regulation and, by these means, are thought to play an important role in plasticity, learning and memory and in several neuropathologies. Within the CNS, the transcription factors of the POU family bind their target DNA sequences after a growth factor-dependent phosphorylation-dephosphorylation cascade. Exposure of cultured Bergmann glial cells to glutamate leads to a time- and dose-dependent increase in Oct-2 DNA-binding activity. The use of specific pharmacological tools established the involvement of Ca2+-permeable alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors. Furthermore, the signaling cascade includes phosphatidyl inositol 3-kinase as well as protein kinase C activation. Interestingly, transcriptional as well as translational inhibitors abolish the glutamate effect, suggesting a transcriptional up-regulation of the oct-2 gene. These data demonstrate that Oct-2 expression is not restricted to neurons and further strengthen the notion that the glial glutamate receptors participate in the modulation of glutamatergic cerebellar neurotransmission.

  6. Stimulation of lateral hypothalamic glutamate and acetylcholine efflux by nicotine: implications for mechanisms of nicotine-induced activation of orexin neurons.

    PubMed

    Pasumarthi, Ravi K; Fadel, Jim

    2010-05-01

    The hypothalamus is a prominent target of nicotine action. We have previously shown that acute systemic nicotine treatment induces Fos expression in the lateral hypothalamus and perifornical area (LH/PFA), with orexin/hypocretin neurons being particularly responsive. However, the neurochemical correlates of acute nicotine treatment in the LH/PFA have not been described. Anatomical studies have revealed that this area receives afferents from cholinergic, glutamatergic, and GABAergic telencephalic brain regions, suggesting a potential role for these neurotransmitters in mediating the hypothalamic component of nicotine effects on homeostatic phenomena, such as arousal and appetite. Here, we used in vivo microdialysis to determine the effect of acute systemic or local nicotine on glutamate, acetylcholine, and GABA efflux in the LH/PFA of rats. Local administration of nicotine significantly increased acetylcholine and glutamate, but not GABA, in the LH/PFA. Thus, we further tested the role of afferent sources of glutamate and acetylcholine in mediating acute nicotine-induced activation of orexin neurons by unilaterally lesioning the prefrontal cortex or basal forebrain cholinergic regions. Lesioned animals showed reduced Fos-positive orexin neurons following nicotine treatment. These data suggest that both acetylcholine and glutamate may mediate the effects of acute nicotine on the activity of hypothalamic neurons, including orexin/hypocretin cells. Changes in cholinergic or glutamatergic transmission in this region with chronic nicotine may contribute to long-term alterations in functions mediated by LH/PFA neurons, including feeding and arousal.

  7. [Dmt(1)]DALDA analogues with enhanced μ opioid agonist potency and with a mixed μ/κ opioid activity profile.

    PubMed

    Bai, Longxiang; Li, Ziyuan; Chen, Jiajia; Chung, Nga N; Wilkes, Brian C; Li, Tingyou; Schiller, Peter W

    2014-04-01

    Analogues of [Dmt(1)]DALDA (H-Dmt-d-Arg-Phe-Lys-NH2; Dmt=2',6'-dimethyltyrosine), a potent μ opioid agonist peptide with mitochondria-targeted antioxidant activity, were prepared by replacing Phe(3) with various 2',6'-dialkylated Phe analogues, including 2',6'-dimethylphenylalanine (Dmp), 2',4',6'-trimethylphenylalanine (Tmp), 2'-isopropyl-6'-methylphenylalanine (Imp) and 2'-ethyl-6'-methylphenylalanine (Emp), or with the bulky amino acids 3'-(1-naphthyl)alanine (1-Nal), 3'-(2-naphthyl)alanine (2-Nal) or Trp. Several compounds showed significantly increased μ agonist potency, retained μ receptor selectivity and are of interest as drug candidates for neuropathic pain treatment. Surprisingly, the Dmp(3)-, Imp(3)-, Emp(3)- and 1-Nal(3)-containing analogues showed much increased κ receptor binding affinity and had mixed μ/κ properties. In these cases, molecular dynamics studies indicated conformational preorganization of the unbound peptide ligands due to rotational restriction around the C(β)C(γ) bond of the Xxx(3) residue, in correlation with the observed κ receptor binding enhancement. Compounds with a mixed μ/κ opioid activity profile are known to have therapeutic potential for treatment of cocaine abuse.

  8. Methylglyoxal and carboxyethyllysine reduce glutamate uptake and S100B secretion in the hippocampus independently of RAGE activation.

    PubMed

    Hansen, Fernanda; Battú, Cíntia Eickhoff; Dutra, Márcio Ferreira; Galland, Fabiana; Lirio, Franciane; Broetto, Núbia; Nardin, Patrícia; Gonçalves, Carlos-Alberto

    2016-02-01

    Diabetes is a metabolic disease characterized by high fasting-glucose levels. Diabetic complications have been associated with hyperglycemia and high levels of reactive compounds, such as methylglyoxal (MG) and advanced glycation endproducts (AGEs) formation derived from glucose. Diabetic patients have a higher risk of developing neurodegenerative diseases, such as Alzheimer's disease or Parkinson's disease. Herein, we examined the effect of high glucose, MG and carboxyethyllysine (CEL), a MG-derived AGE of lysine, on oxidative, metabolic and astrocyte-specific parameters in acute hippocampal slices, and investigated some of the mechanisms that could mediate these effects. Glucose, MG and CEL did not alter reactive oxygen species (ROS) formation, glucose uptake or glutamine synthetase activity. However, glutamate uptake and S100B secretion were decreased after MG and CEL exposure. RAGE activation and glycation reactions, examined by aminoguanidine and L-lysine co-incubation, did not mediate these changes. Acute MG and CEL exposure, but not glucose, were able to induce similar effects on hippocampal slices, suggesting that conditions of high glucose concentrations are primarily toxic by elevating the rates of these glycation compounds, such as MG, and by generation of protein cross-links. Alterations in the secretion of S100B and the glutamatergic activity mediated by MG and AGEs can contribute to the brain dysfunction observed in diabetic patients.

  9. Glutamatergic or GABAergic neuron-specific, long-term expression in neocortical neurons from helper virus-free HSV-1 vectors containing the phosphate-activated glutaminase, vesicular glutamate transporter-1, or glutamic acid decarboxylase promoter.

    PubMed

    Rasmussen, Morten; Kong, Lingxin; Zhang, Guo-rong; Liu, Meng; Wang, Xiaodan; Szabo, Gabor; Curthoys, Norman P; Geller, Alfred I

    2007-05-01

    Many potential uses of direct gene transfer into neurons require restricting expression to one of the two major types of forebrain neurons, glutamatergic or GABAergic neurons. Thus, it is desirable to develop virus vectors that contain either a glutamatergic or GABAergic neuron-specific promoter. The brain/kidney phosphate-activated glutaminase (PAG), the product of the GLS1 gene, produces the majority of the glutamate for release as neurotransmitter, and is a marker for glutamatergic neurons. A PAG promoter was partially characterized using a cultured kidney cell line. The three vesicular glutamate transporters (VGLUTs) are expressed in distinct populations of neurons, and VGLUT1 is the predominant VGLUT in the neocortex, hippocampus, and cerebellar cortex. Glutamic acid decarboxylase (GAD) produces GABA; the two molecular forms of the enzyme, GAD65 and GAD67, are expressed in distinct, but largely overlapping, groups of neurons, and GAD67 is the predominant form in the neocortex. In transgenic mice, an approximately 9 kb fragment of the GAD67 promoter supports expression in most classes of GABAergic neurons. Here, we constructed plasmid (amplicon) Herpes Simplex Virus (HSV-1) vectors that placed the Lac Z gene under the regulation of putative PAG, VGLUT1, or GAD67 promoters. Helper virus-free vector stocks were delivered into postrhinal cortex, and the rats were sacrificed 4 days or 2 months later. The PAG or VGLUT1 promoters supported approximately 90% glutamatergic neuron-specific expression. The GAD67 promoter supported approximately 90% GABAergic neuron-specific expression. Long-term expression was observed using each promoter. Principles for obtaining long-term expression from HSV-1 vectors, based on these and other results, are discussed. Long-term glutamatergic or GABAergic neuron-specific expression may benefit specific experiments on learning or specific gene therapy approaches. Of note, promoter analyses might identify regulatory elements that determine

  10. Semisynthesis, cytotoxicity, antiviral activity, and drug interaction liability of 7-O-methylated analogues of flavonolignans from milk thistle.

    PubMed

    Althagafy, Hanan S; Graf, Tyler N; Sy-Cordero, Arlene A; Gufford, Brandon T; Paine, Mary F; Wagoner, Jessica; Polyak, Stephen J; Croatt, Mitchell P; Oberlies, Nicholas H

    2013-07-01

    Silymarin, an extract of the seeds of milk thistle (Silybum marianum), is used as an herbal remedy, particularly for hepatoprotection. The main chemical constituents in silymarin are seven flavonolignans. Recent studies explored the non-selective methylation of one flavonolignan, silybin B, and then tested those analogues for cytotoxicity and inhibition of both cytochrome P450 (CYP) 2C9 activity in human liver microsomes and hepatitis C virus infection in a human hepatoma (Huh7.5.1) cell line. In general, enhanced bioactivity was observed with the analogues. To further probe the biological consequences of methylation of the seven major flavonolignans, a series of 7-O-methylflavonolignans were generated. Optimization of the reaction conditions permitted selective methylation at the phenol in the 7-position in the presence of each metabolite's 4-5 other phenolic and/or alcoholic positions without the use of protecting groups. These 7-O-methylated analogues, in parallel with the corresponding parent compounds, were evaluated for cytotoxicity against Huh7.5.1 cells; in all cases the monomethylated analogues were more cytotoxic than the parent compounds. Moreover, parent compounds that were relatively non-toxic and inactive or weak inhibitors of hepatitis C virus infection had enhanced cytotoxicity and anti-HCV activity upon 7-O-methylation. Also, the compounds were tested for inhibition of major drug metabolizing enzymes (CYP2C9, CYP3A4/5, UDP-glucuronsyltransferases) in pooled human liver or intestinal microsomes. Methylation of flavonolignans differentially modified inhibitory potency, with compounds demonstrating both increased and decreased potency depending upon the compound tested and the enzyme system investigated. In total, these data indicated that monomethylation modulates the cytotoxic, antiviral, and drug interaction potential of silymarin flavonolignans.

  11. An exploration of the estrogen receptor transcription activity of capsaicin analogues via an integrated approach based on in silico prediction and in vitro assays.

    PubMed

    Li, Juan; Ma, Duo; Lin, Yuan; Fu, Jianjie; Zhang, Aiqian

    2014-06-16

    Capsaicin has been considered as an alternative template of dichlorodiphenyl trichloroethane (DDT) in antifouling paint. However, information regarding the estrogenic activity of capsaicin analogues is rather limited in comparison to that of DDT analogues and their metabolites. We here explore the ER transcription activity of selected capsaicin analogues via an integrated approach based on in silico prediction and in vitro assays. Molecular simulation and the agonist/antagonist differential-docking screening identified 6-iodonordihydrocapsaicin (6-I-CPS) as a weak ERα agonist, while anti-estrogenicity was expected for N-arachidonoyldopamine, capsazepine, dihydrocapsaicin, trichostatin A, and capsaicin. On the contrary, the large volume of analogues, such as phorbol 12-phenylacetate 13-acetate 20-homovanillate and phorbol 12,13-dinonanoate 20-homovanillate, cannot fit well with the ER cavity. The result of MVLN assay was in accord with the in silico prediction. 6-I-CPS was demonstrated to induce luciferase gene expression, while the other analogues of relatively small molecular volume reduced luciferase gene expression in MVLN cells, both in the absence and presence of estradiol. This finding suggested that the ER transcription activity of capsaicin analogues is generated at least partly through the ERα-mediated pathway. Moreover, receptor polymorphism analysis indicated that capsaicin analogues may exhibit diverse species selectivity for human beings and marine species.

  12. Active-site mutations of diphtheria toxin: effects of replacing glutamic acid-148 with aspartic acid, glutamine, or serine.

    PubMed

    Wilson, B A; Reich, K A; Weinstein, B R; Collier, R J

    1990-09-18

    Glutamic acid-148, an active-site residue of diphtheria toxin identified by photoaffinity labeling with NAD, was replaced with aspartic acid, glutamine, or serine by directed mutagenesis of the F2 fragment of the toxin gene. Wild-type and mutant F2 proteins were synthesized in Escherichia coli, and the corresponding enzymic fragment A moieties (DTA) were derived, purified, and characterized. The Glu----Asp (E148D), Glu----Gln (E148Q), and Glu----Ser (E148S) mutations caused reductions in NAD:EF-2 ADP-ribosyltransferase activity of ca. 100-, 250-, and 300-fold, respectively, while causing only minimal changes in substrate affinity. The effects of the mutations on NAD-glycohydrolase activity were considerably different; only a 10-fold reduction in activity was observed for E148S, and the E148D and E148Q mutants actually exhibited a small but reproducible increase in NAD-glycohydrolytic activity. Photolabeling by nicotinamide-radiolabeled NAD was diminished ca. 8-fold in the E148D mutant and was undetectable in the other mutants. The results confirm that Glu-148 plays a crucial role in the ADP-ribosylation of EF-2 and imply an important function for the side-chain carboxyl group in catalysis. The carboxyl group is also important for photochemical labeling by NAD but not for NAD-glycohydrolase activity. The pH dependence of the catalytic parameters for the ADP-ribosyltransferase reaction revealed a group in DTA-wt that titrates with an apparent pKa of 6.2-6.3 and is in the protonated state in the rate-determining step.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Effect of ageing and ischemia on enzymatic activities linked to Krebs' cycle, electron transfer chain, glutamate and aminoacids metabolism of free and intrasynaptic mitochondria of cerebral cortex.

    PubMed

    Villa, Roberto Federico; Gorini, Antonella; Hoyer, Siegfried

    2009-12-01

    The effect of ageing and the relationships between the catalytic properties of enzymes linked to Krebs' cycle, electron transfer chain, glutamate and aminoacid metabolism of cerebral cortex, a functional area very sensitive to both age and ischemia, were studied on mitochondria of adult and aged rats, after complete ischemia of 15 minutes duration. The maximum rate (Vmax) of the following enzyme activities: citrate synthase, malate dehydrogenase, succinate dehydrogenase for Krebs' cycle; NADH-cytochrome c reductase as total (integrated activity of Complex I-III), rotenone sensitive (Complex I) and cytochrome oxidase (Complex IV) for electron transfer chain; glutamate dehydrogenase, glutamate-oxaloacetate-and glutamate-pyruvate transaminases for glutamate metabolism were assayed in non-synaptic, perikaryal mitochondria and in two populations of intra-synaptic mitochondria, i.e., the light and heavy mitochondrial fraction. The results indicate that in normal, steady-state cerebral cortex, the value of the same enzyme activity markedly differs according (a) to the different populations of mitochondria, i.e., non-synaptic or intra-synaptic light and heavy, (b) and respect to ageing. After 15 min of complete ischemia, the enzyme activities of mitochondria located near the nucleus (perikaryal mitochondria) and in synaptic structures (intra-synaptic mitochondria) of the cerebral tissue were substantially modified by ischemia. Non-synaptic mitochondria seem to be more affected by ischemia in adult and particularly in aged animals than the intra-synaptic light and heavy mitochondria. The observed modifications in enzyme activities reflect the metabolic state of the tissue at each specific experimental condition, as shown by comparative evaluation with respect to the content of energy-linked metabolites and substrates. The derangements in enzyme activities due to ischemia is greater in aged than in adult animals and especially the non-synaptic and the intra-synaptic light

  14. Regulation of Synaptic Transmission by Ambient Extracellular Glutamate

    PubMed Central

    FEATHERSTONE, DAVID E.; SHIPPY, SCOTT A.

    2008-01-01

    Many neuroscientists assume that ambient extracellular glutamate concentrations in the nervous system are biologically negligible under nonpathological conditions. This assumption is false. Hundreds of studies over several decades suggest that ambient extracellular glutamate levels in the intact mammalian brain are ~0.5 to ~5 μM. This has important implications. Glutamate receptors are desensitized by glutamate concentrations significantly lower than needed for receptor activation; 0.5 to 5 μM of glutamate is high enough to cause constitutive desensitization of most glutamate receptors. Therefore, most glutamate receptors in vivo may be constitutively desensitized, and ambient extracellular glutamate and receptor desensitization may be potent but generally unrecognized regulators of synaptic transmission. Unfortunately, the mechanisms regulating ambient extracellular glutamate and glutamate receptor desensitization remain poorly understood and understudied. PMID:17947494

  15. Probing the leucyl/phenylalanyl tRNA protein transferase active site with tRNA substrate analogues.

    PubMed

    Fung, Angela Wai Shan; Ebhardt, H Alexander; Krishnakumar, Kollappillil S; Moore, Jack; Xu, Zhizhong; Strazewski, Peter; Fahlman, Richard P

    2014-07-01

    Aminoacyl-tRNA protein transferases post-translationally conjugate an amino acid from an aminoacyl-tRNA onto the N-terminus of a target polypeptide. The eubacterial aminoacyl-tRNA protein transferase, L/F transferase, utilizes both leucyl-tRNA(Leu) and phenylalanyl-tRNA(Phe) as substrates. X-ray crystal structures with substrate analogues, the minimal substrate phenylalanyl adenosine (rA-Phe) and inhibitor puromycin, have been used to characterize tRNA recognition by L/F transferase. However analyses of these two X-ray crystal structures reveal significant differences in binding. Through structural analyses, mutagenesis, and enzymatic activity assays, we rationalize and demonstrate that the substrate analogues bind to L/F transferase with similar binding affinities using a series of different interactions by the various chemical groups of the analogues. Our data also demonstrates that enlarging the hydrophobic pocket of L/F transferase selectively enhances puromycin inhibition and may aid in the development of improved inhibitors for this class of enzymes.

  16. Exploring human adenosine A3 receptor complementarity and activity for adenosine analogues modified in the ribose and purine moiety

    PubMed Central

    Van Rompaey, Philippe; Jacobson, Kenneth A.; Gross, Ariel S.; Gao, Zhan-Guo; Van Calenbergh, Serge

    2012-01-01

    In this paper we investigated the influence on affinity, selectivity and intrinsic activity upon modification of the adenosine agonist scaffold at the 3′- and 5′-positions of the ribofuranosyl moiety and the 2- and N6-positions of the purine base. This resulted in the synthesis of various analogues, that is, 3–12 and 24–33, with good hA3AR selectivity and moderate-to-high affinities (as in 32, Ki = 27 nM). Interesting was the ability to tune the intrinsic activity depending on the substituent introduced at the 3′-position. PMID:15670905

  17. Brain energy metabolism in glutamate-receptor activation and excitotoxicity: role for APC/C-Cdh1 in the balance glycolysis/pentose phosphate pathway.

    PubMed

    Rodriguez-Rodriguez, Patricia; Almeida, Angeles; Bolaños, Juan P

    2013-04-01

    Recent advances in the field of brain energy metabolism strongly suggest that glutamate receptor-mediated neurotransmission is coupled with molecular signals that switch-on glucose utilization pathways to meet the high energetic requirements of neurons. Failure to adequately coordinate energy supply for neurotransmission ultimately results in a positive amplifying loop of receptor over-activation leading to neuronal death, a process known as excitotoxicity. In this review, we revisited current concepts in excitotoxic mechanisms, their involvement in energy substrate utilization, and the signaling pathways that coordinate both processes. In particular, we have focused on the novel role played by the E3 ubiquitin ligase, anaphase-promoting complex/cyclosome (APC/C)-Cdh1, in cell metabolism. Our laboratory identified 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3) -a key glycolytic-promoting enzyme- as an APC/C-Cdh1 substrate. Interestingly, APC/C-Cdh1 activity is inhibited by over-activation of glutamate receptors through a Ca(2+)-mediated mechanism. Furthermore, by inhibiting APC/C-Cdh1 activity, glutamate-receptors activation promotes PFKFB3 stabilization, leading to increased glycolysis and decreased pentose-phosphate pathway activity. This causes a loss in neuronal ability to regenerate glutathione, triggering oxidative stress and delayed excitotoxicity. Further investigation is critical to identify novel molecules responsible for the coupling of energy metabolism with glutamatergic neurotransmission and excitotoxicity, as well as to help developing new therapeutic strategies against neurodegeneration.

  18. [Autoimmune mechanisms of modulation of the activity of glutamate receptors in children with epilepsy and craniocerebral injury].

    PubMed

    Pinelis, V G; Sorokina, E G

    2008-01-01

    The role of glutamate receptors and their hyperstimulation in the development of autoimmune processes is discussed with reference to brain pathology associated with hypoxia and ischemia. Epilepsy, paroxismal condition, and craniocerebral injury (CCI) in children are shown to be accompanied by a rise in the levels of antibodies against AMPA and NMDA receptors of glutamate and nitric oxide markers (cGMP, nitrates + nitrites). Also enhanced in epilepsy and paroxismal condition are the levels of cGMP and antibodies against AMPA(GluR1) receptors of glutamate. Acute CCI period is characterized by a marked change in the levels of NO metabolites and antibodies to two subtypes of glutamate receptor, AMPA and NMDA. The levels of antibodies to NMDA(NR2A) receptors are significantly different within 1 day after CCI depending on its outcome. Unfavourable outcome of CCI is associated with the lowest level of antibodies and high NO metabolite content. Relationship between the levels of NO and antibodies against glutamate receptors is discussed with the use of experimental data. It is concluded that antibodies to glutamate receptors and receptor hyperstimulation play an important role in pathogenesis of hypoxia. PMID:19189459

  19. Osmium Bisterpyridine Complexes with Redox-Active Amine Substituents: A Comparison Study with Ruthenium Analogues.

    PubMed

    Sun, Meng-Jia; Shao, Jiang-Yang; Yao, Chang-Jiang; Zhong, Yu-Wu; Yao, Jiannian

    2015-08-17

    Five osmium complexes with redox-active amine substituents, [Os(ttpy)(Ntpy)](PF6)2 (1(PF6)2), [Os(Ntpy)2](PF6)2 (2(PF6)2), [Os(ttpy)(NPhtpy)](PF6)2 (3(PF6)2), [Os(Ntpy)(NPhtpy)](PF6)2 (4(PF6)2), and [Os(NPhtpy)2](PF6)2 (5(PF6)2), have been prepared, where ttpy is 4'-tolyl-2,2':6',2″-terpyridine, Ntpy is 4'-(di-p-anisylamino)-2,2':6',2″-terpyridine, and NPhtpy is 4'-(di-p-anisylaminophen-4-yl)-2,2':6',2″-terpyridine. X-ray crystallographic data of 2(PF6)2 and 4(PF6)2 are presented. These complexes show rich visible absorptions attributed to the singlet metal-to-ligand charge-transfer ((1)MLCT), triplet MLCT, and intraligand charge-transfer transitions. Complexes 3(PF6)2 and 5(PF6)2 show weak emissions around 720 nm at room temperature. All complexes show stepwise oxidations of the osmium ion and the amine segment. However, the redox potentials and the order of the Os(III/II) and N(•+/0) processes vary significantly, depending on the electronic nature of the amine substituents. In the singly oxidized state, either Os(II) → N(•+) MLCT or N → Os(III) ligand-to-metal charge-transfer transitions in the near-infrared region have been observed. For complexes 2(PF6)2, 4(PF6)2, and 5(PF6)2 with two amine substituents, no evidence has been observed for the presence of osmium-mediated amine-amine electronic coupling. Density functional theory (DFT) and time-dependent DFT calculations have been performed to complement these experimental results. The one-electron-oxidized forms 3(3+) and 5(3+) show distinct electron paramagnetic resonance (EPR) signals in CH3CN at room temperature. However, complexes 1(3+), 2(3+), and 4(3+) are EPR silent under similar conditions. In addition, a comparison study has been made between these osmium complexes and the previously reported ruthenium analogues. PMID:26237331

  20. Synthesis of new 3,20-bispolyaminosteroid squalamine analogues and evaluation of their antimicrobial activities.

    PubMed

    Djouhri-Bouktab, Lamia; Vidal, Nicolas; Rolain, Jean Marc; Brunel, Jean Michel

    2011-10-27

    3,20-Amino- and polyaminosteroid analogues of squalamine and trodusquemine were synthesized involving a stereoselective titanium reductive amination reaction in high chemical yields in numerous cases. These derivatives were evaluated for their in vitro antimicrobial properties against references and clinical bacterial strains exhibiting minimum inhibitory concentrations of 2.5-40 μg/mL. The mechanism of action of these derivatives was determined using bioluminescence for ATP efflux measurements and fluorescence methods for membrane depolarization assays. PMID:21905738

  1. Scavenging of blood glutamate for enhancing brain-to-blood glutamate efflux.

    PubMed

    Li, Yunhong; Hou, Xiaolin; Qi, Qi; Wang, Le; Luo, Lan; Yang, Shaoqi; Zhang, Yumei; Miao, Zhenhua; Zhang, Yanli; Wang, Fei; Wang, Hongyan; Huang, Weidong; Wang, Zhenhai; Shen, Ying; Wang, Yin

    2014-01-01

    The presence of excess glutamate in the brain interstitial fluid characterizes several acute pathological conditions of the brain, including traumatic brain injury and stroke. It has been demonstrated that it is possible to eliminate excess glutamate in the brain by decreasing blood glutamate levels and, accordingly, accelerating the brain-to-blood glutamate efflux. It is feasible to accomplish this process by activating blood resident enzymes in the presence of the respective glutamate cosubstrates. In the present study, several glutamate cosubstrates and cofactors were studied in an attempt to identify the optimal conditions to reduce blood glutamate levels. The administration of a mixture of 1 mM pyruvate and oxaloacetate (Pyr/Oxa) for 1 h decreased blood glutamate levels by ≤50%. The addition of lipoamide to this mixture resulted in a further reduction in blood glutamate levels of >80%. In addition, in vivo experiments showed that lipoamide together with Pyr/Oxa is able to decrease blood glutamate levels to a greater extent than Pyr/Oxa alone, and accordingly, this enhances the glutamate efflux from the brain to the blood. These results may outline a novel neuroprotective strategy with increased effectiveness for the removal of excess brain glutamate in various neurodegenerative conditions.

  2. Neuronal activity patterns in the mediodorsal thalamus and related cognitive circuits are modulated by metabotropic glutamate receptors

    PubMed Central

    Copeland, C.S.; Neale, S.A.; Salt, T.E.

    2015-01-01

    The mediodorsal thalamus (MD) likely plays an important role in cognition as it receives abundant afferent connections from the amygdala and prefrontal cortex (PFC). Indeed, disturbed activity within the MD is thought to precipitate cognitive deficits associated with schizophrenia. As compounds acting at the Group II metabotropic glutamate (mGlu) receptors (subtypes mGlu2/mGlu3) have efficacy in animal models of schizophrenia, we investigated whether a Group II agonist and an mGlu2 positive allosteric modulator (PAM) could modulate MD activity. Extracellular single-unit recordings were made in vivo from MD neurones in anaesthetised rats. Responses were elicited by electrical stimulation of the PFC and/or amygdala, with Group II compounds locally applied as required. The Group II agonist reduced inhibition evoked in the MD: an effect manifested as an increase in short-latency responses, and a decrease in long-latency burst-firing. This disinhibitory action of the Group II receptors in the MD represents a mechanism of potential therapeutic importance as increased inhibition in the MD has been associated with cognitive deficit-onset. Furthermore, as co-application of the mGlu2 PAM did not potentiate the Group II agonist effects in the MD, we suggest that the Group II disinhibitory effect is majority-mediated via mGlu3. This heterogeneity in Group II receptor thalamic physiology bears consequence, as compounds active exclusively at the mGlu2 subtype are unlikely to perturb maladapted MD firing patterns associated with cognitive deficits, with activity at mGlu3 receptors possibly more appropriate. Indeed, polymorphisms in the mGlu3, but not the mGlu2, gene have been detected in patients with schizophrenia. PMID:25576798

  3. Neuronal activity patterns in the mediodorsal thalamus and related cognitive circuits are modulated by metabotropic glutamate receptors.

    PubMed

    Copeland, C S; Neale, S A; Salt, T E

    2015-05-01

    The mediodorsal thalamus (MD) likely plays an important role in cognition as it receives abundant afferent connections from the amygdala and prefrontal cortex (PFC). Indeed, disturbed activity within the MD is thought to precipitate cognitive deficits associated with schizophrenia. As compounds acting at the Group II metabotropic glutamate (mGlu) receptors (subtypes mGlu2/mGlu3) have efficacy in animal models of schizophrenia, we investigated whether a Group II agonist and an mGlu2 positive allosteric modulator (PAM) could modulate MD activity. Extracellular single-unit recordings were made in vivo from MD neurones in anaesthetised rats. Responses were elicited by electrical stimulation of the PFC and/or amygdala, with Group II compounds locally applied as required. The Group II agonist reduced inhibition evoked in the MD: an effect manifested as an increase in short-latency responses, and a decrease in long-latency burst-firing. This disinhibitory action of the Group II receptors in the MD represents a mechanism of potential therapeutic importance as increased inhibition in the MD has been associated with cognitive deficit-onset. Furthermore, as co-application of the mGlu2 PAM did not potentiate the Group II agonist effects in the MD, we suggest that the Group II disinhibitory effect is majority-mediated via mGlu3. This heterogeneity in Group II receptor thalamic physiology bears consequence, as compounds active exclusively at the mGlu2 subtype are unlikely to perturb maladapted MD firing patterns associated with cognitive deficits, with activity at mGlu3 receptors possibly more appropriate. Indeed, polymorphisms in the mGlu3, but not the mGlu2, gene have been detected in patients with schizophrenia. PMID:25576798

  4. Antinociceptive activity of a synthetic curcuminoid analogue, 2,6-bis-(4-hydroxy-3-methoxybenzylidene)cyclohexanone, on nociception-induced models in mice.

    PubMed

    Ming-Tatt, Lee; Khalivulla, Shaik Ibrahim; Akhtar, Muhammad Nadeem; Mohamad, Azam Shah; Perimal, Enoch Kumar; Khalid, Mohamed Hanief; Akira, Ahmad; Lajis, Nordin; Israf, Daud Ahmad; Sulaiman, Mohd Roslan

    2012-03-01

    This study investigated the potential antinociceptive efficacy of a novel synthetic curcuminoid analogue, 2,6-bis-(4-hydroxy-3-methoxybenzylidene)cyclohexanone (BHMC), using chemical- and thermal-induced nociception test models in mice. BHMC (0.03, 0.1, 0.3 and 1.0 mg/kg) administered via intraperitoneal route (i.p.) produced significant dose-related inhibition in the acetic acid-induced abdominal constriction test in mice with an ID(50) of 0.15 (0.13-0.18) mg/kg. It was also demonstrated that BHMC produced significant inhibition in both neurogenic (first phase) and inflammatory phases (second phase) of the formalin-induced paw licking test with an ID(50) of 0.35 (0.27-0.46) mg/kg and 0.07 (0.06-0.08) mg/kg, respectively. Similarly, BHMC also exerted significant increase in the response latency period in the hot-plate test. Moreover, the antinociceptive effect of the BHMC in the formalin-induced paw licking test and the hot-plate test was antagonized by pre-treatment with the non-selective opioid receptor antagonist, naloxone. Together, these results indicate that the compound acts both centrally and peripherally. In addition, administration of BHMC exhibited significant inhibition of the neurogenic nociception induced by intraplantar injections of glutamate and capsaicin with ID(50) of 0.66 (0.41-1.07) mg/kg and 0.42 (0.38-0.51) mg/kg, respectively. Finally, it was also shown that BHMC-induced antinociception was devoid of toxic effects and its antinociceptive effect was associated with neither muscle relaxant nor sedative action. In conclusion, BHMC at all doses investigated did not cause any toxic and sedative effects and produced pronounced central and peripheral antinociceptive activities. The central antinociceptive activity of BHMC was possibly mediated through activation of the opioid system as well as inhibition of the glutamatergic system and TRPV1 receptors, while the peripheral antinociceptive activity was perhaps mediated through inhibition of

  5. Isoprenyl-thiourea and urea derivatives as new farnesyl diphosphate analogues: synthesis and in vitro antimicrobial and cytotoxic activities.

    PubMed

    Vega-Pérez, José M; Periñán, Ignacio; Argandoña, Montserrat; Vega-Holm, Margarita; Palo-Nieto, Carlos; Burgos-Morón, Estefanía; López-Lázaro, Miguel; Vargas, Carmen; Nieto, Joaquín J; Iglesias-Guerra, Fernando

    2012-12-01

    A series of new isoprenyl-thiourea and urea derivatives were synthesized by the reaction of alkyl or aryl isothiocyanate or isocyanate and primary amines. The structures of the compounds were established by (1)H NMR, (13)C NMR, MS, HRMS and elemental analysis. The new compounds were screened for in vitro antimicrobial activity against seven strains representing different types of gram-positive and gram-negative bacteria. More than a third of the synthesized compounds showed variable inhibition activities against the tested strains. Best antimicrobial activities were found for those thiourea analogues with 3-methyl-2-butenyl, isobutyl or isopentyl groups and aromatic rings possessing electron withdrawing substituents. The new compounds were also subjected to a preliminary screening for antitumoral activity. The presence of a highly lipophilic group and an electron withdrawing group in the aromatic rings enhanced anticancer activity of the synthesized compounds, showing in most cases more activity than that of the controls.

  6. Interplay among platelet-activating factor, oxidative stress, and group I metabotropic glutamate receptors modulates neuronal survival.

    PubMed

    Zhu, Peimin; DeCoster, Mark A; Bazan, Nicolas G

    2004-08-15

    Platelet-activating factor (PAF) is a potent phospholipid messenger in the nervous system that participates in synaptic plasticity and in pathologic processes, including neurodegeneration. Oxidative stress plays important roles in neuronal cell death. To define the interaction between PAF and oxidative radicals in neuronal death, we studied the effects of PAF in the presence of oxidative radicals in primary neurons in culture. Exogenous PAF (50 microM) caused PAF receptor-independent injury to neurons. A nonneurotoxic PAF concentration (500 nM) potentiated neuronal death caused by hydrogen peroxide as determined by lactate dehydrogenase (LDH) assay, Hoechst staining, and TUNEL analysis, but it did not potentiate neuronal death caused by menadione, a superoxide donor, or by the nitric oxide donors 3-morpholino-sydnonimine (SIN-1) and sodium nitroprusside (SNP). This potentiation of the hydrogen peroxide effect was selectively blocked by a PAF membrane-receptor antagonist, BN52021 (5 microM). The neurotoxic effect of PAF and hydrogen peroxide was also completely blocked by ebselen and partially decreased by pretreatment with (S)-3,5-dihydroxyphenylglycine (DHPG), a group I metabotropic glutamate receptor (mGluR) agonist. This study suggests that PAF-receptor antagonists may be useful for neuroprotection. A similar effect might also be obtained with group I mGluR agonists, probably by way of a different underlying mechanism.

  7. Heteroaryl analogues of AMPA. 2. Synthesis, absolute stereochemistry, photochemistry, and structure-activity relationships.

    PubMed

    Falch, E; Brehm, L; Mikkelsen, I; Johansen, T N; Skjaerbaek, N; Nielsen, B; Stensbøl, T B; Ebert, B; Krogsgaard-Larsen, P

    1998-07-01

    We have previously shown that (S)-2-amino-3-(3-hydroxy-5-phenyl-4-isoxazolyl)propionic acid [(S)-APPA, 2] is a weak agonist at (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptors, specifically activated by (S)-AMPA (1), whereas (S)-2-amino-3-[3-hydroxy-5-(2-pyridyl)-4-isoxazolyl]propionic acid [(S)-2-Py-AMPA, 5] and (RS)-2-amino-3-[3-hydroxy-5-(2-thiazolyl)-4-isoxazolyl]propionic acid (4) are potent AMPA agonists. On the other hand, (R)-APPA (3) and (R)-2-Py-AMPA (6) have been shown to be weak AMPA antagonists. We now report the synthesis of 2-Py-AMPA (7a) and the isomeric compounds 3-Py-AMPA (7b) and 4-Py-AMPA (7c) as well as the 7a analogues, (RS)-2-amino-3-[3-hydroxy-5-(6-methyl-2-pyridyl)-4-isoxazolyl]p ropion ic acid (7d) and (RS)-2-amino-3-[3-hydroxy-5-(2-quinolinyl)-4-isoxazolyl]propionic acid (7e). Furthermore, (RS)-2-amino-3-[3-hydroxy-5-(2-furyl)-4-isoxazolyl]propionic acid (2-Fu-AMPA, 7f) and its 5-bromo-2-furyl derivative (7g) were synthesized, and (S)-2-Fu-AMPA (8) and (R)-2-Fu-AMPA (9) were prepared by semipreparative chiral HPLC resolution of 7f. HPLC analyses and circular dichroism spectroscopy indicated the absolute stereochemistry of 8 and 9 to be S and R, respectively. This was confirmed by an X-ray crystallographic analysis of 9.HCl. In receptor binding (IC50 values) and rat cortical wedge electrophysiological (EC50 values) studies, 7c (IC50 = 5.5 +/- 0.6 microM; EC50 = 96 +/- 5 microM) was shown to be markedly weaker than 7a (IC50 = 0.57 +/- 0.16 microM; EC50 = 7.4 +/- 0.2 microM) as an AMPA agonist, whereas 7b,d,e were inactive. The very potent AMPA agonist effect of 7f (IC50 = 0.15 +/- 0.03 microM; EC50 = 1.7 +/- 0. 2 microM) was shown to reside exclusively in 8 (IC50 = 0.11 +/- 0.01 microM; EC50 = 0.71 +/- 0.11 microM), whereas 9 did not interact significantly with AMPA receptors, either as an agonist or as an antagonist. 8 was shown to be photochemically active and is a potential photoaffinity label for the

  8. Peptidyl prolyl isomerase Pin1-inhibitory activity of D-glutamic and D-aspartic acid derivatives bearing a cyclic aliphatic amine moiety.

    PubMed

    Nakagawa, Hidehiko; Seike, Suguru; Sugimoto, Masatoshi; Ieda, Naoya; Kawaguchi, Mitsuyasu; Suzuki, Takayoshi; Miyata, Naoki

    2015-12-01

    Pin1 is a peptidyl prolyl isomerase that specifically catalyzes cis-trans isomerization of phosphorylated Thr/Ser-Pro peptide bonds in substrate proteins and peptides. Pin1 is involved in many important cellular processes, including cancer progression, so it is a potential target of cancer therapy. We designed and synthesized a novel series of Pin1 inhibitors based on a glutamic acid or aspartic acid scaffold bearing an aromatic moiety to provide a hydrophobic surface and a cyclic aliphatic amine moiety with affinity for the proline-binding site of Pin1. Glutamic acid derivatives bearing cycloalkylamino and phenylthiazole groups showed potent Pin1-inhibitory activity comparable with that of known inhibitor VER-1. The results indicate that steric interaction of the cyclic alkyl amine moiety with binding site residues plays a key role in enhancing Pin1-inhibitory activity.

  9. Overview of analogue science activities at the McGill Arctic Research Station, Axel Heiberg Island, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Pollard, Wayne; Haltigin, Tim; Whyte, Lyle; Niederberger, Thomas; Andersen, Dale; Omelon, Christopher; Nadeau, Jay; Ecclestone, Miles; Lebeuf, Martin

    2009-05-01

    The Canadian High Arctic contains several of the highest fidelity Mars analogue sites in the world. Situated at nearly 80° north, Expedition Fjord on Axel Heiberg Island is located within a polar desert climate, with the surrounding landscape and conditions providing an invaluable opportunity to examine terrestrial processes in a cold, dry environment. Through the Canadian Space Agency's Analogue Research Network program, scientific activities based out of the McGill Arctic Research Station (M.A.R.S.) are extremely broad in scope, representing physical, biological, and technological investigations. Some of the most unique hydrogeologic features under investigation near M.A.R.S. are a series of cold saline springs that maintain liquid-state flow year round regardless of air temperature. Previous studies have examined their geomorphic relation to discharge-related formations, water chemistry, temperature monitoring, discharge rates, and combined flow/thermal modeling. Recent investigations have identified microbial communities and characterized biological activity within the springs and within permafrost sections, having direct relevance to astrobiological analogue research goals. Another main thrust of research activities based at M.A.R.S. pertains to the detection, mapping, and quantification of subsurface ice deposits. A long-term study is presently underway examining polygonal terrain, comparing surficial patterns found in the region with those identified on Mars, and using surface morphology to estimate ice wedge volumes through a combination of aerial photography interpretation and ground-based geophysical techniques. Other technological developments include the use of in situ microscopy for the detection of biomarkers and improved permafrost drilling techniques. This paper presents an overview of previous studies undertaken at M.A.R.S. over the past decades and will describe in detail both present and upcoming work.

  10. Coordinated activation of distinct Ca2+ sources and metabotropic glutamate receptors encodes Hebbian synaptic plasticity

    PubMed Central

    Tigaret, Cezar M.; Olivo, Valeria; Sadowski, Josef H.L.P.; Ashby, Michael C.; Mellor, Jack R.

    2016-01-01

    At glutamatergic synapses, induction of associative synaptic plasticity requires time-correlated presynaptic and postsynaptic spikes to activate postsynaptic NMDA receptors (NMDARs). The magnitudes of the ensuing Ca2+ transients within dendritic spines are thought to determine the amplitude and direction of synaptic change. In contrast, we show that at mature hippocampal Schaffer collateral synapses the magnitudes of Ca2+ transients during plasticity induction do not match this rule. Indeed, LTP induced by time-correlated pre- and postsynaptic spikes instead requires the sequential activation of NMDARs followed by voltage-sensitive Ca2+ channels within dendritic spines. Furthermore, LTP requires inhibition of SK channels by mGluR1, which removes a negative feedback loop that constitutively regulates NMDARs. Therefore, rather than being controlled simply by the magnitude of the postsynaptic calcium rise, LTP induction requires the coordinated activation of distinct sources of Ca2+ and mGluR1-dependent facilitation of NMDAR function. PMID:26758963

  11. Design, synthesis, and SAR of embelin analogues as the inhibitors of PAI-1 (plasminogen activator inhibitor-1).

    PubMed

    Chen, Fanglei; Zhang, Guiping; Hong, Zebin; Lin, Zhonghui; Lei, Min; Huang, Mingdong; Hu, Lihong

    2014-05-15

    The natural product embelin was found to have PAI-1 inhibitory activity with the IC50 value of 4.94μM. Based on the structure of embelin, a series of analogues were designed, synthesized, and evaluated for their ability to inhibit PAI-1. The SAR study on these compounds disclosed that the inhibitory potency largely depended on the hydroxyl groups at C2 and C5, and the length of the alkyl chains at C3 and C6. Compound 11 displayed the best PAI-1 inhibitory potency with the IC50 value of 0.18μM.

  12. Impact of fumonisin B1 on glutamate toxicity and low magnesium-induced seizure activity in neuronal primary culture.

    PubMed

    Domijan, A-M; Kovac, S; Abramov, A Y

    2012-01-27

    Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium spp. mould that contaminates maize world-wide. Although its neurodegenerative potential is well established, mechanisms and acute effects of FB(1) on neurons are still not completely understood. Our previous study on astrocytes and neuroblastoma cells demonstrated that acute FB(1) exposure inhibits mitochondrial complex I and leads to mitochondrial membrane potential depolarization and calcium deregulation. To further explore the mechanisms of FB(1) neurotoxicity, we here investigated the effects of acute FB(1) co-exposure with glutamate and in the low magnesium model of epilepsy on neuronal calcium level, mitochondrial membrane potential, and cell death in glio-neuronal cultures. FB(1) increased the glutamate-induced calcium signal in neurons and changed neuronal calcium signals to more sustained intracellular calcium rises in the low magnesium model of epilepsy that coincided with mitochondrial membrane potential depolarization. FB(1) co-exposure increased the percentage of dead neurons in low magnesium conditions dose dependently when compared with low magnesium exposure only, whereas in FB(1) and glutamate co-exposure neuronal death remained unchanged when compared with glutamate treatment only. Our results show that FB(1) makes neurons more vulnerable to glutamate-induced toxicity and epileptiform conditions, indicating that FB(1) can enhance the detrimental effect of these conditions on neurons. PMID:22178271

  13. Glutamate regulates kainate-binding protein expression in cultured chick Bergmann glia through an activator protein-1 binding site.

    PubMed

    Aguirre, A; López, T; López-Bayghen, E; Ortega, A

    2000-12-15

    The expression of the chick kainate-binding protein, a member of the ionotropic glutamate receptor family, is restricted to the cerebellum, specifically to Bergmann glia. Glutamate induces a membrane to nuclei signaling involved in gene expression regulation. Exposure of cultured chick Bergmann glia cells to glutamate leads to an increase in kainate binding protein and mRNA levels, suggesting a transcriptional level of regulation. The 5' proximal region of the chick kainate binding gene was cloned and transfected 4into Bergmann glia cells. Three main regulatory regions could be defined, a minimal promoter region, a negative regulatory region, and interestingly, a glutamate-responsive element. Deletion of this element abolishes the agonist effect. Moreover, electrophoretic mobility shift assays, cotransfection experiments, and site-directed mutagenesis clearly suggest that the glutamate effect is mediated through an AP-1 site by a Fos/Jun heterodimer. The present results favor the notion of a functional role of kainate-binding protein in glutamatergic cerebellar neurotransmission.

  14. Block by gabapentin of the facilitation of glutamate release from rat trigeminal nucleus following activation of protein kinase C or adenylyl cyclase

    PubMed Central

    Maneuf, Yannick P; McKnight, Alexander T

    2001-01-01

    The effect of activation of protein kinase C (PKC) or adenylyl cyclase on release of glutamate has been investigated in a perfused slice preparation from the rat caudal trigeminal nucleus. Stimulation of PKC by phorbol 12-myristate 13-acetate (PMA) produced a concentration-dependent increase in K+-evoked release of [2H]-glutamate (maximum increase 45%, EC50 11.8 nM), but in the presence of gabapentin (30 μM) the facilitation of release was blocked. The adenylyl cyclase activator forskolin (FSK) also induced a concentration-dependent increase in K+-evoked release of [3H]-glutamate (maximum increase 36%, EC50 2.4 μM), and again this facilitatory effect was blocked by gabapentin (30 μM). We suggest that these results may be of relevance to the antihyperalgesic properties of gabapentin, in conditions where concomitant release of substance P and CGRP produces activation of PKC and adenylyl cyclase respectively. PMID:11564640

  15. Activation of the Glutamic Acid-Dependent Acid Resistance System in Escherichia coli BL21(DE3) Leads to Increase of the Fatty Acid Biotransformation Activity

    PubMed Central

    Woo, Ji-Min; Kim, Ji-Won; Song, Ji-Won; Blank, Lars M.; Park, Jin-Byung

    2016-01-01

    The biosynthesis of carboxylic acids including fatty acids from biomass is central in envisaged biorefinery concepts. The productivities are often, however, low due to product toxicity that hamper whole-cell biocatalyst performance. Here, we have investigated factors that influence the tolerance of Escherichia coli to medium chain carboxylic acid (i.e., n-heptanoic acid)-induced stress. The metabolic and genomic responses of E. coli BL21(DE3) and MG1655 grown in the presence of n-heptanoic acid indicated that the GadA/B-based glutamic acid-dependent acid resistance (GDAR) system might be critical for cellular tolerance. The GDAR system, which is responsible for scavenging intracellular protons by catalyzing decarboxylation of glutamic acid, was inactive in E. coli BL21(DE3). Activation of the GDAR system in this strain by overexpressing the rcsB and dsrA genes, of which the gene products are involved in the activation of GadE and RpoS, respectively, resulted in acid tolerance not only to HCl but also to n-heptanoic acid. Furthermore, activation of the GDAR system allowed the recombinant E. coli BL21(DE3) expressing the alcohol dehydrogenase of Micrococcus luteus and the Baeyer-Villiger monooxygenase of Pseudomonas putida to reach 60% greater product concentration in the biotransformation of ricinoleic acid (i.e., 12-hydroxyoctadec-9-enoic acid (1)) into n-heptanoic acid (5) and 11-hydroxyundec-9-enoic acid (4). This study may contribute to engineering E. coli-based biocatalysts for the production of carboxylic acids from renewable biomass. PMID:27681369

  16. In vitro and in vivo activity of LS 4477 and LS 4559, novel analogues of the tubulin binder estramustine.

    PubMed

    Nicholson, K M; Phillips, R M; Shnyder, S D; Bibby, M C

    2002-01-01

    LS 4477 and LS 4559, two of a series of N-acyl-aminoalkyl phenyl ethers, are rationally designed compounds based on the tubulin binder estramustine. This study investigated their mechanism of action and compared their effectiveness in relation to estramustine in vitro against a panel of human and murine cell lines and in vivo against two murine colon tumour models (MAC). At biologically relevant concentrations, LS 4477 and LS 4559 caused a 59.9 and 56% reduction in tubulin assembly, respectively, compared with a 28.4% reduction in tubulin assembly by estramustine. The analogues were approximately 100 times more potent in chemosensitivity tests in vitro than the parent compound. Both analogues were orally active against the MAC 15A murine tumour model, to a greater extent than estramustine, producing significant growth delays (P<0.01). Significant activity was also shown against the slower growing MAC 26 tumour for LS 4577 (the soluble pro-drug of LS 4559). The results presented in this study suggest these compounds warrant further development with a view to assessing their clinical activity.

  17. Synthesis and anticoagulant activity of bioisosteric sulfonic-Acid analogues of the antithrombin-binding pentasaccharide domain of heparin.

    PubMed

    Herczeg, Mihály; Lázár, László; Bereczky, Zsuzsanna; Kövér, Katalin E; Timári, István; Kappelmayer, János; Lipták, András; Antus, Sándor; Borbás, Anikó

    2012-08-20

    Two pentasaccharide sulfonic acids that were related to the antithrombin-binding domain of heparin were prepared, in which two or three primary sulfate esters were replaced by sodium-sulfonatomethyl moieties. The sulfonic-acid groups were formed on a monosaccharide level and the obtained carbohydrate sulfonic-acid esters were found to be excellent donors and acceptors in the glycosylation reactions. Throughout the synthesis, the hydroxy groups to be methylated were masked in the form of acetates and the hydroxy groups to be sulfated were masked with benzyl groups. The disulfonic-acid analogue was prepared in a [2+3] block synthesis by using a trisaccharide disulfonic acid as an acceptor and a glucuronide disaccharide as a donor. For the synthesis of the pentasaccharide trisulfonic acid, a more-efficient approach, which involved elongation of the trisaccharide acceptor with a non-oxidized precursor of the glucuronic acid followed by post-glycosidation oxidation at the tetrasaccharide level and a subsequent [1+4] coupling reaction, was elaborated. In vitro evaluation of the anticoagulant activity of these new sulfonic-acid derivatives revealed that the disulfonate analogue inhibited the blood-coagulation-proteinase factor Xa with outstanding efficacy; however, the introduction of the third sulfonic-acid moiety resulted in a notable decrease in the anti-Xa activity. The difference in the biological activity of the disulfonic- and trisulfonic-acid counterparts could be explained by the different conformation of their L-iduronic-acid residues.

  18. Structural differences in diarylheptanoids analogues from Alnus viridis and Alnus glutinosa influence their activity and selectivity towards cancer cells.

    PubMed

    Dinić, Jelena; Novaković, Miroslav; Podolski-Renić, Ana; Vajs, Vlatka; Tešević, Vele; Isaković, Aleksandra; Pešić, Milica

    2016-04-01

    Diarylheptanoids represent a group of plant secondary metabolites that possess multiple biological properties and are increasingly recognized for their therapeutic potential. A comparative study was performed on structurally analogous diarylheptanoids isolated from the bark of green (Alnus viridis) and black alder (Alnus glutinosa) to address their biological effects and determine structure-activity relationship. The structures and configurations of all compounds were elucidated by NMR, HR-ESI-MS, UV and IR. Diarylheptanoids actions were studied in human non-small cell lung carcinoma cells (NCI-H460) and normal keratinocytes (HaCaT). A. viridis compounds 3v, 5v, 8v and 9v that possess a carbonyl group at C-3 were considerably more potent than compounds without this group. A. viridis/A. glutinosa analogue pairs, 5v/5g and 9v/9g, which differ in the presence of 3' and 3″-OH groups, were evaluated for anticancer activity and selectivity. 5v and 9v that do not possess 3' and 3″-OH groups showed significantly higher cytotoxicity compared to analogues 5g and 9g. In addition, these two A. viridis compounds induced a more prominent apoptosis in both cell lines and an increase in subG0 cell cycle phase, compared to their A. glutinosa analogues. 5v and 9v treatment triggered intracellular superoxide anion accumulation and notably decreased mitochondrial transmembrane potential. In HaCaT cells, 9v and 9g with a 4,5 double bond caused a more prominent loss of mitochondrial transmembrane potential compared to 5v and 5g which possess a 5-methoxy group instead. Although green alder diarylheptanoids 5v and 9v displayed higher cytotoxicity, their analogues from black alder 5g and 9g could be more favorable for therapeutic use since they were more active in cancer cells than in normal keratinocytes. These results indicate that minor differences in the chemical structure can greatly influence the effect of diarylheptanoids on apoptosis and redox status and determine their

  19. 3D-QSAR Studies on a Series of Dihydroorotate Dehydrogenase Inhibitors: Analogues of the Active Metabolite of Leflunomide

    PubMed Central

    Li, Shun-Lai; He, Mao-Yu; Du, Hong-Guang

    2011-01-01

    The active metabolite of the novel immunosuppressive agent leflunomide has been shown to inhibit the enzyme dihydroorotate dehydrogenase (DHODH). This enzyme catalyzes the fourth step in de novo pyrimidine biosynthesis. Self-organizing molecular field analysis (SOMFA), a simple three-dimensional quantitative structure-activity relationship (3D-QSAR) method is used to study the correlation between the molecular properties and the biological activities of a series of analogues of the active metabolite. The statistical results, cross-validated rCV2 (0.664) and non cross-validated r2 (0.687), show a good predictive ability. The final SOMFA model provides a better understanding of DHODH inhibitor-enzyme interactions, and may be useful for further modification and improvement of inhibitors of this important enzyme. PMID:21686163

  20. High resolution crystal structures of triosephosphate isomerase complexed with its suicide inhibitors: The conformational flexibility of the catalytic glutamate in its closed, liganded active site

    PubMed Central

    Venkatesan, Rajaram; Alahuhta, Markus; Pihko, Petri M; Wierenga, Rik K

    2011-01-01

    The key residue of the active site of triosephosphate isomerase (TIM) is the catalytic glutamate, which is proposed to be important (i) as a catalytic base, for initiating the reaction, as well as (ii) for the subsequent proton shuttling steps. The structural properties of this glutamate in the liganded complex have been investigated by studying the high resolution crystal structures of typanosomal TIM, complexed with three suicide inhibitors: (S)-glycidol phosphate ((S)-GOP, at 0.99 Å resolution), (R)-glycidol phosphate, ((R)-GOP, at 1.08 Å resolution), and bromohydroxyacetone phosphate (BHAP, at 1.97 Å resolution). The structures show that in the (S)-GOP active site this catalytic glutamate is in the well characterized, competent conformation. However, an unusual side chain conformation is observed in the (R)-GOP and BHAP complexes. In addition, Glu97, salt bridged to the catalytic lysine in the competent active site, adopts an unusual side chain conformation in these two latter complexes. The higher chemical reactivity of (S)-GOP compared with (R)-GOP, as known from solution studies, can be understood: the structures indicate that in the case of (S)-GOP, Glu167 can attack the terminal carbon of the epoxide in a stereoelectronically favored, nearly linear O–C–O arrangement, but this is not possible for the (R)-GOP isomer. These structures confirm the previously proposed conformational flexibility of the catalytic glutamate in its closed, liganded state. The importance of this conformational flexibility for the proton shuttling steps in the TIM catalytic cycle, which is apparently achieved by a sliding motion of the side chain carboxylate group above the enediolate plane, is also discussed. PMID:21633986

  1. Role of Glutamate 64 in the Activation of the Prodrug 5-fluorocytosine by Yeast Cytosine Deaminase†

    PubMed Central

    Wang, Jifeng; Sklenak, Stepan; Liu, Aizhuo; Felczak, Krzysztof; Wu, Yan; Li, Yue; Yan, Honggao

    2012-01-01

    Yeast cytosine deaminase catalyzes the hydrolytic deamination of cytosine to uracil as well as the deamination of the prodrug 5-fluorocytosine (5FC) to the anticancer drug 5-fluorouracil. In this study, the role of Glu64 in the activation of the prodrug 5FC was investigated by site-directed mutagenesis, biochemical, NMR, and computational studies. Steady-state kinetics studies showed that the mutation of Glu64 causes a dramatic decrease in kcat and a dramatic increase in Km, indicating Glu64 is important for both binding and catalysis in the activation of 5FC. 19F-NMR experiments showed that binding of the inhibitor 5-fluoro-1H-pyrimidin-2-one (5FPy) to the wild type yCD causes an upfield shift, indicating that the bound inhibitor is in the hydrated form, mimicking the transition state or the tetrahedral intermediate in the activation of 5FC. However, binding of 5FPy to the E64A mutant enzyme causes a downfield shift, indicating that the bound 5FPy remains in an unhydrated form in the complex with the mutant enzyme. 1H and 15N NMR analysis revealed trans-hydrogen-bond D/H isotope effects on the hydrogen of the amide of Glu64, indicating that the carboxylate of Glu64 forms two hydrogen bonds with the hydrated 5FPy. ONIOM calculations showed that the wild type yCD complex with the hydrated form of the inhibitor 1H-pyrimidin-2-one is more stable than the initial binding complex, and in contrast, with the E64A mutant enzyme, the hydrated inhibitor is no longer favored and the conversion has higher activation energy as well. The hydrated inhibitor is stabilized in the wild-type yCD by two hydrogen bonds between it and the carboxylate of Glu64 as revealed by 1H and 15N NMR analysis. To explore the functional role of Glu64 in catalysis, deamination of cytosine catalyzed by the E64A mutant was investigated by ONIOM calculations. The results showed that without the assistance of Glu64, both proton transfers before and after the formation of the tetrahedral reaction

  2. Glutamine Assimilation and Feedback Regulation of L-acetyl-N-glutamate Kinase Activity in Chlorella variabilis NC64A Results in Changes in Arginine Pools.

    PubMed

    Minaeva, Ekaterina; Forchhammer, Karl; Ermilova, Elena

    2015-11-01

    Glutamine is a metabolite of central importance in nitrogen metabolism of microorganisms and plants. The Chlorella PII signaling protein controls, in a glutamine-dependent manner, the key enzyme of the ornithine/arginine biosynthesis pathway, N-acetyl-L-glutamate kinase (NAGK) that leads to arginine formation. We provide evidence that glutamine promotes effective growth of C. variabilis strain NC64A. The present study shows that externally supplied glutamine directly influences the internal pool of arginine in NC64A. Glutamine synthetase (GS) catalyzes the ATP-dependent conversion of glutamate and ammonium to glutamine. The results of this study demonstrate that glutamine acts as a negative effector of GS activity. These data emphasize the importance of glutamine-dependent coupling of metabolism and signaling as components of an efficient pathway allowing the maintenance of metabolic homeostasis and sustaining growth of Chlorella.

  3. Glutamine Assimilation and Feedback Regulation of L-acetyl-N-glutamate Kinase Activity in Chlorella variabilis NC64A Results in Changes in Arginine Pools.

    PubMed

    Minaeva, Ekaterina; Forchhammer, Karl; Ermilova, Elena

    2015-11-01

    Glutamine is a metabolite of central importance in nitrogen metabolism of microorganisms and plants. The Chlorella PII signaling protein controls, in a glutamine-dependent manner, the key enzyme of the ornithine/arginine biosynthesis pathway, N-acetyl-L-glutamate kinase (NAGK) that leads to arginine formation. We provide evidence that glutamine promotes effective growth of C. variabilis strain NC64A. The present study shows that externally supplied glutamine directly influences the internal pool of arginine in NC64A. Glutamine synthetase (GS) catalyzes the ATP-dependent conversion of glutamate and ammonium to glutamine. The results of this study demonstrate that glutamine acts as a negative effector of GS activity. These data emphasize the importance of glutamine-dependent coupling of metabolism and signaling as components of an efficient pathway allowing the maintenance of metabolic homeostasis and sustaining growth of Chlorella. PMID:26356535

  4. A lentiviral vector-based genetic sensor system for comparative analysis of permeability and activity of vitamin D3 analogues in xenotransplanted human skin.

    PubMed

    Staunstrup, Nicklas Heine; Bak, Rasmus O; Cai, Yujia; Svensson, Lars; Petersen, Thomas K; Rosada, Cecilia; Stenderup, Karin; Bolund, Lars; Mikkelsen, Jacob Giehm

    2013-03-01

    Vitamin D3 analogues are widely used topical and oral remedies for various ailments such as psoriasis, osteoporosis and secondary hyperparathyroidism. In topical treatment, high skin permeability and cellular uptake are key criteria for beneficial effects due to the natural barrier properties of skin. In this study, we wish to establish an in vivo model that allows the comparison of permeability and activity of vitamin D3 analogues in human skin. We generate a bipartite, genetic sensor technology that combines efficient lentivirus-directed gene delivery to xenotransplanted human skin with vitamin D3-induced expression of a luciferase reporter gene and live imaging of animals by bioluminescence imaging. Based on the induction of a transcriptional activator consisting of the vitamin D receptor fused to the Gal4 DNA-binding domain, the vitamin D3-responsive sensor facilitates non-invasive and rapid assessment of permeability and functional properties of vitamin D3 analogues. By topical application of a panel of vitamin D3 analogues onto 'sensorized' human skin, the sensor produces a drug-induced readout with a magnitude and persistence that allow a direct comparative analysis of different analogues. This novel genetic tool has great potential as a non-invasive in vivo screening system for further development and refinement of vitamin D3 analogues.

  5. Glutamate Transporter-Mediated Glutamate Secretion in the Mammalian Pineal Gland

    PubMed Central

    Kim, Mean-Hwan; Uehara, Shunsuke; Muroyama, Akiko; Hille, Bertil; Moriyama, Yoshinori; Koh, Duk-Su

    2008-01-01

    Glutamate transporters are expressed throughout the central nervous system where their major role is to clear released glutamate from presynaptic terminals. Here we report a novel function of the transporter in rat pinealocytes. This electrogenic transporter conducted inward current in response to L-glutamate and L- or D-aspartate and depolarized the membrane in patch clamp experiments. Ca2+ imaging demonstrated that the transporter-mediated depolarization induced a significant Ca2+ influx through voltage-gated Ca2+ channels. The Ca2+ rise finally evoked glutamate exocytosis as detected by carbon-fiber amperometry and by high-performance liquid chromatography. In pineal slices with densely packed pinealocytes, glutamate released from the cells effectively activated glutamate transporters in neighboring cells. The Ca2+ signal generated by KCl depolarization or acetylcholine propagated through several cell layers by virtue of the regenerative ‘glutamate-induced glutamate release’. Therefore we suggest that glutamate transporters mediate synchronized elevation of L-glutamate and thereby efficiently down-regulate melatonin secretion via previously identified inhibitory metabotropic glutamate receptors in the pineal gland. PMID:18945893

  6. Type I beta-turn conformation is important for biological activity of the melanocyte-stimulating hormone analogues.

    PubMed

    Li, S Z; Lee, J H; Lee, W; Yoon, C J; Baik, J H; Lim, S K

    1999-10-01

    In order to define which structure of alpha-melanocyte-stimulating hormone (MSH) analogues plays a critical role for ligand-receptor interaction and selectivity, we analysed receptor-binding and cAMP-generating activity in Chinese hamster ovary cell lines stably transfected with rMC3R and hMC4R, as well as the NMR structures of chemically synthesized alpha-MSH analogues. Compared with [Ahx4]alpha-MSH, the linear MTII designated as alpha-MSH-ND revealed a preference for the MC4R, whereas its IC50 and EC50 values were comparable to those of MTII reported previously. Truncation of Ahx4 and Asp5 of alpha-MSH-ND remarkably decreased the receptor-binding and cAMP-generating activity. Meanwhile, maximum cAMP-generating activity was observed at a higher concentration (10(-5) M) of alpha-MSH-ND(6-10), and MC4R preference was changed into MC3R preference. In contrast, [Gln6]alpha-MSH-ND(6-10) lost its cAMP-generating activity almost completely, even though it bound to both receptors. Whereas the solution conformation of alpha-MSH-ND revealed a stable type I beta-turn structure, [Gln6]alpha-MSH-ND(6-10) revealed a tight gamma-turn composed of Gln6-D-Phe7-Arg8. Replacement of the His6 residue of alpha-MSH-ND by Gln, Asn, Arg or Lys decreased not only the receptor binding, but also the cAMP-generating activity in both the MC3R and the MC4R. The structure of [Gln6]alpha-MSH-ND exhibited a stable type I' beta-turn comprising Asp5, Gln6, D-Phe7 and Arg8. [Lys6]alpha-MSH-ND showed a greatly reduced binding affinity and cAMP-generating activity with the loss of MC4R selectivity. In NMR studies, [Lys6]alpha-MSH-ND also demonstrated a gamma-turn conformation around Lys6-DPhe7-Arg8. From the above results, we conclude that a type I beta-turn conformation comprising the residues Asp5-His6-(D-Phe7)-Arg8 was important for receptor binding and activation, as well as the selectivity of MSH analogues.

  7. Nuclear pore complex evolution: a trypanosome Mlp analogue functions in chromosomal segregation but lacks transcriptional barrier activity

    PubMed Central

    Holden, Jennifer M.; Koreny, Ludek; Obado, Samson; Ratushny, Alexander V.; Chen, Wei-Ming; Chiang, Jung-Hsien; Kelly, Steven; Chait, Brian T.; Aitchison, John D.; Rout, Michael P.; Field, Mark C.

    2014-01-01

    The nuclear pore complex (NPC) has dual roles in nucleocytoplasmic transport and chromatin organization. In many eukaryotes the coiled-coil Mlp/Tpr proteins of the NPC nuclear basket have specific functions in interactions with chromatin and defining specialized regions of active transcription, whereas Mlp2 associates with the mitotic spindle/NPC in a cell cycle–dependent manner. We previously identified two putative Mlp-related proteins in African trypanosomes, TbNup110 and TbNup92, the latter of which associates with the spindle. We now provide evidence for independent ancestry for TbNup92/TbNup110 and Mlp/Tpr proteins. However, TbNup92 is required for correct chromosome segregation, with knockout cells exhibiting microaneuploidy and lowered fidelity of telomere segregation. Further, TbNup92 is intimately associated with the mitotic spindle and spindle anchor site but apparently has minimal roles in control of gene transcription, indicating that TbNup92 lacks major barrier activity. TbNup92 therefore acts as a functional analogue of Mlp/Tpr proteins, and, together with the lamina analogue NUP-1, represents a cohort of novel proteins operating at the nuclear periphery of trypanosomes, uncovering complex evolutionary trajectories for the NPC and nuclear lamina. PMID:24600046

  8. Mechanism of hyperinsulinism in short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency involves activation of glutamate dehydrogenase.

    PubMed

    Li, Changhong; Chen, Pan; Palladino, Andrew; Narayan, Srinivas; Russell, Laurie K; Sayed, Samir; Xiong, Guoxiang; Chen, Jie; Stokes, David; Butt, Yasmeen M; Jones, Patricia M; Collins, Heather W; Cohen, Noam A; Cohen, Akiva S; Nissim, Itzhak; Smith, Thomas J; Strauss, Arnold W; Matschinsky, Franz M; Bennett, Michael J; Stanley, Charles A

    2010-10-01

    The mechanism of insulin dysregulation in children with hyperinsulinism associated with inactivating mutations of short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) was examined in mice with a knock-out of the hadh gene (hadh(-/-)). The hadh(-/-) mice had reduced levels of plasma glucose and elevated plasma insulin levels, similar to children with SCHAD deficiency. hadh(-/-) mice were hypersensitive to oral amino acid with decrease of glucose level and elevation of insulin. Hypersensitivity to oral amino acid in hadh(-/-) mice can be explained by abnormal insulin responses to a physiological mixture of amino acids and increased sensitivity to leucine stimulation in isolated perifused islets. Measurement of cytosolic calcium showed normal basal levels and abnormal responses to amino acids in hadh(-/-) islets. Leucine, glutamine, and alanine are responsible for amino acid hypersensitivity in islets. hadh(-/-) islets have lower intracellular glutamate and aspartate levels, and this decrease can be prevented by high glucose. hadh(-/-) islets also have increased [U-(14)C]glutamine oxidation. In contrast, hadh(-/-) mice have similar glucose tolerance and insulin sensitivity compared with controls. Perifused hadh(-/-) islets showed no differences from controls in response to glucose-stimulated insulin secretion, even with addition of either a medium-chain fatty acid (octanoate) or a long-chain fatty acid (palmitate). Pull-down experiments with SCHAD, anti-SCHAD, or anti-GDH antibodies showed protein-protein interactions between SCHAD and GDH. GDH enzyme kinetics of hadh(-/-) islets showed an increase in GDH affinity for its substrate, α-ketoglutarate. These studies indicate that SCHAD deficiency causes hyperinsulinism by activation of GDH via loss of inhibitory regulation of GDH by SCHAD.

  9. Effect of activity at metabotropic, as well as ionotropic (NMDA), glutamate receptors on morphine dependence.

    PubMed Central

    Fundytus, M E; Coderre, T J

    1994-01-01

    1. The contribution of various excitatory amino acid (EAA) receptors (NMDA, AMPA/kainate and metabotropic) in the brain to the development of morphine dependence was examined. This was performed by measuring the severity of the precipitated withdrawal syndrome following chronic subcutaneous (s.c.) morphine and intracerebroventricular (i.c.v.) EAA antagonist treatment. 2. Continuous subcutaneous (s.c.) treatment with morphine sulphate (36.65 mumol day-1) produced an intense and reliable naloxone-precipitated withdrawal syndrome. 3. Chronic i.c.v. treatment with antagonists selective for metabotropic and NMDA receptors, but not AMPA/kainate receptors, significantly attenuated abstinence symptoms. Conversely, EAA antagonists had very little effect on non-withdrawal behaviours. 4. These results suggest that, as well as changes elicited by activation of NMDA receptors, metabotropic receptors and intracellular changes in the phosphatidylinositol (PI) second-messenger system or the cyclic adenosine 3',5'-monophosphate (cAMP) second messenger system, to which EAA metabotropic receptors are linked, may be involved in the development of opioid dependence with chronic morphine treatment. PMID:7889275

  10. Concomitant activation of two types of glutamate receptor mediates excitation of salamander retinal ganglion cells.

    PubMed Central

    Mittman, S; Taylor, W R; Copenhagen, D R

    1990-01-01

    faster non-NMDA-receptor-mediated component having a time-to-peak of 28 +/- 10 ms and an e-fold decay time of 43 +/- 20 ms at -31 mV (n = 8). 7. A similar analysis of sustained EPSCs of on ganglion cells showed that these currents resulted from sustained activation of both NMDA and non-NMDA receptors. PMID:2172521

  11. Utilizing an Extraterrestrial Analogue to Predict Sediment Migration on Frenchman Flat due to Convective Vortex (Dust Devil) Activity

    NASA Astrophysics Data System (ADS)

    McGee, B. W.

    2006-12-01

    A synthesis of terrestrial and Martian data suggests that a convective vortex, or "dust devil," is a significant, non-random terrestrial eolian sediment transport phenomenon, which has implications for sediment-based migration of radionuclides on Frenchman Flat playa, a 20 square-mile mountain-bounded dry lake bed approximately centered in Frenchman Flat on the Nevada Test Site (NTS). Planetary scientists are often forced to rely on terrestrial analogues to begin characterizing extraterrestrial processes. However, as the planetary database matures, an increasing number of well-characterized extraterrestrial analogues for terrestrial processes will become available. Such analogues may provide a convenient means to investigate poorly understood or otherwise inaccessible terrestrial phenomena. Historical atmospheric nuclear experiments conducted from 1951 to 1962 deposited radionuclides into surface sediments across parts of Frenchman Flat playa, where dust devils are known to commonly occur, especially during the summer months. Recent information from both terrestrial and Martian studies yields that dust devils can be significant contributors to both the local eolian sediment transport regime and the regional climate system. Additionally, the use of terrestrial desert environments as Martian analogues, as well as the recent, unique discovery of Mars-like dust devil tracks in Africa, has established a working correlation between Earth, Mars, and the dust devil phenomenon. However, while the difficulty in tracking dust devil paths on Earth has hindered the determination of any net sediment transport due to dust devils, the dramatic albedo contrast in disturbed sediment on Mars lends to the formation of persistent, curvilinear dust devil tracks. These tracks illustrate that in zones of preferential formation, dust devils possess non-random orientations over seasonal timescales with respect to prevailing wind. By calibrating these Martian orientations with meteorological

  12. Direct synthesis of imino-C-nucleoside analogues and other biologically active iminosugars

    PubMed Central

    Bergeron-Brlek, Milan; Meanwell, Michael; Britton, Robert

    2015-01-01

    Iminosugars have attracted increasing attention as chemical probes, chaperones and leads for drug discovery. Despite several clinical successes, their de novo synthesis remains a significant challenge that also limits their integration with modern high-throughput screening technologies. Herein, we describe a unique synthetic strategy that converts a wide range of acetaldehyde derivatives into iminosugars and imino-C-nucleoside analogues in two or three straightforward transformations. We also show that this strategy can be readily applied to the rapid production of indolizidine and pyrrolizidine iminosugars. The high levels of enantio- and diastereoselectivity, excellent overall yields, convenience and broad substrate scope make this an appealing process for diversity-oriented synthesis, and should enable drug discovery efforts. PMID:25903019

  13. Thiamine pyrophosphate stimulates acetone activation by Desulfococcus biacutus as monitored by a fluorogenic ATP analogue.

    PubMed

    Gutiérrez Acosta, Olga B; Hardt, Norman; Hacker, Stephan M; Strittmatter, Tobias; Schink, Bernhard; Marx, Andreas

    2014-06-20

    Acetone can be degraded by aerobic and anaerobic microorganisms. Studies with the strictly anaerobic sulfate-reducing bacterium Desulfococcus biacutus indicate that acetone degradation by these bacteria starts with an ATP-dependent carbonylation reaction leading to acetoacetaldehyde as the first reaction product. The reaction represents the second example of a carbonylation reaction in the biochemistry of strictly anaerobic bacteria, but the exact mechanism and dependence on cofactors are still unclear. Here, we use a novel fluorogenic ATP analogue to investigate its mechanism. We find that thiamine pyrophosphate is a cofactor of this ATP-dependent reaction. The products of ATP cleavage are AMP and pyrophosphate, providing first insights into the reaction mechanism by indicating that the reaction proceeds without intermediate formation of acetone enol phosphate.

  14. Effects of a thyrotropin releasing hormone analogue on locomotor and other motor activity in the rat.

    PubMed

    Clarke, K A; Parker, A J

    1985-04-01

    In the present experiments, locomotion has been studied in rats after injection of TRH analogue RX77368 (10 mg/kg i.p.). The measure used was the frequency of the cyclic shifts of weight from side to side (WTF) which accompany the progress of locomotion. It therefore provides an indirect measure of stepping frequency. After injection of RX77368 there was a shift in WTFs towards higher frequencies, i.e. when the rat walked it was taking more steps per second. These results suggest that RX77368 stimulates basic motor patterns associated with locomotion. The results obtained in these experiments are compared with those obtained using different quantification methods for locomotion and there is speculation concerning the possible modes of action of RX77368 including interactions with other neurotransmitter systems. PMID:3923383

  15. Combretastatin A-4 analogues with benzoxazolone scaffold: Synthesis, structure and biological activity.

    PubMed

    Gerova, Mariana S; Stateva, Silviya R; Radonova, Elena M; Kalenderska, Rositsa B; Rusew, Rusi I; Nikolova, Rositsa P; Chanev, Christo D; Shivachev, Boris L; Apostolova, Margarita D; Petrov, Ognyan I

    2016-09-14

    In order to design and synthesize a new class of heterocyclic analogues of natural combretastatin A-4 and its synthetic derivative AVE8062, the benzoxazolone ring was selected as a scaffold for a bioisosteric replacement of the ring B of both molecules. A library of 28 cis- and trans-styrylbenzoxazolones was obtained by a modified Wittig reaction under Boden's conditions. Structures of the newly synthesized compounds bearing the 3,4,5-trimethoxy-, 3,4-dimethoxy-, 3,5-dimethoxy-, and 4-methoxystyryl fragment at position 4, 5, 6 or 7 of benzoxazolone core were determined on the basis of spectral and X ray data. The in vitro cytotoxicity of styrylbenzoxazolones against different cell lines was examined. Stilbene derivative 16Z, (Z)-3-methyl-6-(3,4,5-trimethoxystyryl)-2(3H)-benzoxazolone, showed highest antiproliferative potential of the series, with IC50 of 0.25 μM against combretastatin resistant cell line HT-29, 0.19 μM against HepG2, 0.28 μM against EA.hy926 and 0.73 μM against K562 cells. Furthermore, the results of flow cytometric analysis confirmed that 16Z induced cell cycle arrest in G2/M phase in the cell lines like combretastatin A-4. This arrest is followed by an abnormal exit of cells from mitosis without cytokinesis into a pseudo G1-like multinucleate state leading to late apoptosis and cell death. Accordingly, synthetic analogue 16Z was identified as the most promising potential anticancer agent in present study, and was selected as lead compound for further detailed investigations. PMID:27187864

  16. Dideoxy nucleoside triphosphate (ddNTP) analogues: Synthesis and polymerase substrate activities of pyrrolidinyl nucleoside triphosphates (prNTPs).

    PubMed

    Gade, Chandrasekhar Reddy; Dixit, Manjusha; Sharma, Nagendra K

    2016-09-15

    The dideoxynucleoside triphosphates (ddNTPs) terminate the bio-polymerization of DNA and become essential chemical component of DNA sequencing technology which is now basic tool for molecular biology research. In this method the radiolabeled or fluorescent dye labeled ddNTP analogues are being used for DNA sequencing by detection of the terminated DNA fragment after single labeled ddNTP incorporation into DNA under PCR conditions. This report describes the syntheses of rationally designed novel amino-functionalized ddNTP analogue such as Pyrrolidine nucleoside triphosphates (prNTPs), and their polymerase activities with DNA polymerase by LC-MS and Gel-electrophoretic techniques. The Mass and PAGE analyses strongly support the incorporation of prNTPs into DNA oligonucleotide with Therminator DNA polymerase as like control substrate ddNTP. As resultant the DNA oligonucleotide are functionalized as amine group by prNTP incorporation with polymerase. Hence prNTPs provide opportunities to prepare demandable conjugated DNA with other biomolecules/dyes/fluorescence molecule without modifying nucleobase structure. PMID:27377861

  17. The pivotal role of uridine-cytidine kinases in pyrimidine metabolism and activation of cytotoxic nucleoside analogues in neuroblastoma.

    PubMed

    van Kuilenburg, André B P; Meinsma, Rutger

    2016-09-01

    Uridine-cytidine kinase (UCK) catalyzes the phosphorylation of uridine and cytidine as well as the pharmacological activation of several cytotoxic pyrimidine ribonucleoside analogues. In this study, we investigated the functional role of two isoforms of UCK in neuroblastoma cell lines. Analysis of mRNA coding for UCK1 and UCK2 showed that UCK2 is the most abundantly expressed UCK in a panel of neuroblastoma cell lines. Transient and stable overexpression of UCK2 in neuroblastoma cells increased the metabolism of uridine and cytidine as well as the cytotoxicity of 3-deazauridine. Knockdown of endogenous UCK2 as well as overexpression of UCK1 resulted in decreased metabolism of uridine and cytidine and protected the neuroblastoma cells from 3-deazauridine-induced toxicity. Subcellular localization studies showed that UCK1-GFP and UCK2-GFP were localized in the cell nucleus and cytosol, respectively. However, co-expression of UCK1 with UCK2 resulted in a nuclear localization of UCK2 instead of its normal cytosolic localization, thereby impairing its normal function. The physical association of UCK1 and UCK2 was further demonstrated through pull-down analysis using his-tagged UCK. The discovery that UCK2 is highly expressed in neuroblastoma opens the possibility for selectively targeting neuroblastoma cells using UCK2-dependent pyrimidine analogues, while sparing normal tissues. PMID:27239701

  18. Automated docking of monosaccharide substrates and analogues and methyl alpha-acarviosinide in the glucoamylase active site.

    PubMed

    Coutinho, P M; Dowd, M K; Reilly, P J

    1997-02-01

    Glucoamylase is an important industrial glucohydrolase with a large specificity range. To investigate its interaction with the monosaccharides D-glucose, D-mannose, and D-galactose and with the substrate analogues 1-deoxynojirimycin, D-glucono-1,5-lactone, and methyl alpha-acarviosinide, MM3(92)-optimized structures were docked into its active site using AutoDock 2.1. The results were compared to structures of glucoamylase complexes obtained by protein crystallography. Charged forms of some substrate analogues were also docked to assess the degree of protonation possessed by glucoamylase inhibitors. Many forms of methyl alpha-acarviosinide were conformationally mapped by using MM3(92), characterizing the conformational pH dependence found for the acarbose family of glucosidase inhibitors. Their significant conformers, representing the most common states of the inhibitor, were used as initial structures for docking. This constitutes a new approach for the exploration of binding modes of carbohydrate chains. Docking results differ slightly from x-ray crystallographic data, the difference being of the order of the crystallographic error. The estimated energetic interactions, even though agreeing in some cases with experimental binding kinetics, are only qualitative due to the large approximations made by AutoDock force field.

  19. Synthesis and in vitro antitumor activity of new deaza analogues of the nonpolyglutamatable antifolate N(alpha)-(4-amino-4-deoxypteroyl)-N(delta)-hemiphthaloyl-L-ornithine (PT523).

    PubMed

    Vaidya, Chitra M; Wright, Joel E; Rosowsky, Andre

    2002-04-11

    Details are disclosed for the synthesis of N(alpha)-[4-[2-(2,4-diaminoquinazolin-6-yl)ethyl]benzoyl]-N(delta)-hemiphthaloyl-L-ornithine (2) and N(alpha)-[4-[5-(2,4-diaminoteridin-6-yl)pent-1-yn-4-yl]benzoyl]-N(delta)-hemiphthaloyl-L-ornithine (6) as analogues of N(alpha)-(4-amino-4-deoxypteroyl)-N(delta)-hemiphthaloyl-L-ornithine (1, PT523), a nonpolyglutamatable antifolate currently in advanced preclinical development. In a 72 h growth inhibition assay against cultures of CCRF-CEM human leukemic lymphoblasts, the IC(50) of 2 and 6 was 0.69 +/- 0.044 nM and 1.3 +/- 0.35 nM, respectively, as compared with previously reported values 4.4 +/- 0.10 nM for aminopterin (AMT) and 1.5 +/- 0.39 nM for PT523. In a spectrophotometric assay of dihydrofolate reductase (DHFR) inhibition using dihydrofolate and NADPH as the cosubstrates, the previously unreported compounds 2 and the mixed 10R and 10S diastereomers of 6 had K(i) values of 0.21 +/- 0.05 pM and 0.60 +/- 0.02 pM, respectively, as compared with previously reported values of 3.70 +/- 0.35 pM for AMT and 0.33 +/- 0.04 pM for PT523. Thus, while they were comparable to 1 and several of its previously studied analogues in their ability to bind to DHFR and inhibit the growth of CCRF-CEM cells, 2 and the mixed diastereomers of 6 were several times more active than AMT despite the fact that they cannot form gamma-polyglutamylated metabolites of the type formed in cells from AMT and other classical antifolates with a glutamate side chain.

  20. Synthesis, Nitric Oxide Release, and Anti-Leukemic Activity of Glutathione-Activated Nitric Oxide Prodrugs: Structural Analogues of PABA/NO, an Anti-Cancer Lead Compound

    PubMed Central

    Chakrapani, Harinath; Wilde, Thomas C.; Citro, Michael L.; Goodblatt, Michael M.; Keefer, Larry K.; Saavedra, Joseph E.

    2008-01-01

    Diazeniumdiolate anions and their prodrug forms are reliable sources of nitric oxide (NO) that have generated interest as promising therapeutic agents. A number of structural analogues of O2-(2,4-dinitro-5-(4-(N-methylamino)benzoyloxy)phenyl) 1-(N,N-dimethylamino)diazen-1-ium-1,2-diolate (PABA/NO), an anti-cancer lead compound that is designed to release NO upon activation by glutathione, were prepared. The nitric oxide release patterns of these O2-(2,4-dinitrophenyl) diazeniumdiolates in the presence of glutathione were tested and it was found that in the absence of competing pathways, these compounds release nearly quantitative amounts of NO. The ability of PABA/NO and its structural analogues to inhibit human leukemia cell proliferation was determined and it was found that compounds releasing elevated amounts of NO displayed superior cytotoxic effects. PMID:18060792

  1. Synthesis, anticancer activity and molecular docking studies on a series of heterocyclic trans-cyanocombretastatin analogues as antitubulin agents.

    PubMed

    Penthala, Narsimha Reddy; Zong, Hongliang; Ketkar, Amit; Madadi, Nikhil Reddy; Janganati, Venumadav; Eoff, Robert L; Guzman, Monica L; Crooks, Peter A

    2015-03-01

    A series of heterocyclic combretastatin analogues have been synthesized and evaluated for their anticancer activity against a panel of 60 human cancer cell lines. The most potent compounds were two 3,4,5-trimethoxy phenyl analogues containing either an (Z)-indol-2-yl (8) or (Z)-benzo[b]furan-2-yl (12) moiety; these compounds exhibited GI50 values of <10 nM against 74% and 70%, respectively, of the human cancer cell lines in the 60-cell panel. Compounds 8, and 12 and two previously reported compounds in the same structural class, i.e. 29 and 31, also showed potent anti-leukemic activity against leukemia MV4-11 cell lines with LD50 values = 44 nM, 47 nM, 18 nM, and 180 nM, respectively. From the NCI anti-cancer screening results and the data from the in vitro toxicity screening on cultured AML cells, seven compounds: 8, 12, 21, 23, 25, 29 and 31 were screened for their in vitro inhibitory activity on tubulin polymerization in MV4-11 AML cells; at 50 nM, 8 and 29 inhibited polymerization of tubulin by >50%. The binding modes of the three most active compounds (8, 12 and 29) to tubulin were also investigated utilizing molecular docking studies. All three molecules were observed to bind in the same hydrophobic pocket at the interface of α- and β-tubulin that is occupied by colchicine, and were stabilized by van der Waals' interactions with surrounding tubulin residues. The results from the tubulin polymerization and molecular docking studies indicate that compounds 8 and 29 are the most potent anti-leukemic compounds in this structural class, and are considered lead compounds for further development as anti-leukemic drugs.

  2. Opioid activity of dermenkephalin analogues in the guinea-pig myenteric plexus and the hamster vas deferens.

    PubMed Central

    Sagan, S.; Corbett, A. D.; Amiche, M.; Delfour, A.; Nicolas, P.; Kosterlitz, H. W.

    1991-01-01

    1. To elucidate the structural features required for selective and potent action of dermenkephalin at the delta-opioid receptor, a series of analogues of dermenkephalin and dermorphin were tested for their effectiveness in depressing electrically-evoked contractions of the vas deferens of the hamster (delta-opioid receptors) and the guinea-pig myenteric plexus-longitudinal muscle preparation (mu- and kappa-opioid receptors). 2. Dermenkephalin was more selective and more potent at delta-receptors than the delta-ligand [D-Pen2, D-Pen5]-enkephalin. The responses to dermenkephalin in the hamster vas deferens were increased by addition of peptidase inhibitors; the maximum effect was obtained with 3 microM thiorphan. 3. [L-Met2]-dermenkephalin had 0.2% and [L-Ala2]-dermorphin 0.01% of the agonist activity of the corresponding endogenous peptides which have D-amino acids in position 2. The pharmacological activity of these analogues was unaffected by inhibition of peptidases. This emphasizes the role that the D-configuration plays in determining the bioactive folding of these highly active peptides. 4. Dermenkephalin-(1-6)-NH2 was more potent at delta-receptors than at mu-receptors whereas, dermenkephalin-(1-4)-NH2 is a selective mu-agonist, having no activity at delta-receptors. 5. Substitution of the C-terminal tripeptide of dermorphin with the C-terminal tripeptide of dermenkephalin abolished the mu-receptor preference of dermorphin. The resulting hybrid peptide, Tyr-D-Ala-Phe-Gly-Leu-Met-Asp-NH2 was as potent as dermenkephalin at delta-receptors. A shift towards a preference for delta-receptors was obtained when the C-terminal tetrapeptide of dermorphin was replaced by the C-terminal tetrapeptide of dermenkephalin.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1665735

  3. Synthesis, anticancer activity and molecular docking studies on a series of heterocyclic trans-cyanocombretastatin analogues as antitubulin agents

    PubMed Central

    Penthala, Narsimha Reddy; Zong, Hongliang; Ketkar, Amit; Madadi, Nikhil Reddy; Janganati, Venumadav; Eoff, Robert L.; Guzman, Monica L.; Crooks, Peter A.

    2015-01-01

    A series of heterocyclic combretastatin analogues have been synthesized and evaluated for their anticancer activity against a panel of 60 human cancer cell lines. The most potent compounds were two 3,4,5-trimethoxy phenyl analogues containing either an (Z)-indol-2-yl (8) or (Z)-benzo[b]furan-2-yl (12) moiety; these compounds exhibited GI50 values of <10 nM against 74% and 70%, respectively, of the human cancer cell lines in the 60-cell panel. Compounds 8, and 12 and two previously reported compounds in the same structural class, i.e. 29 and 31, also showed potent anti-leukemic activity against leukemia MV4-11 cell lines with LD50 values = 44 nM, 47 nM, 18 nM, and 180 nM, respectively. From the NCI anti-cancer screening results and the data from the in vitro toxicity screening on cultured AML cells, seven compounds: 8, 12, 21, 23, 25, 29 and 31 were screened for their in vitro inhibitory activity on tubulin polymerization in MV4-11 AML cells; at 50 nM, 8 and 29 inhibited polymerization of tubulin by >50%. The binding modes of the three most active compounds (8, 12 and 29) to tubulin were also investigated utilizing molecular docking studies. All three molecules were observed to bind in the same hydrophobic pocket at the interface of α- and β-tubulin that is occupied by colchicine, and were stablized by van der Waals’ interactions with surrounding tubulin residues. The results from the tubulin polymerization and molecular docking studies indicate that compounds 8 and 29 are the most potent anti-leukemic compounds in this structural class, and are considered lead compounds for further development as anti-leukemic drugs. PMID:25557492

  4. A membrane-bound form of glutamate dehydrogenase possesses an ATP-dependent high-affinity microtubule-binding activity.

    PubMed Central

    Rajas, F; Rousset, B

    1993-01-01

    We previously identified a 50 kDa membrane protein which bound to in vitro assembled microtubules [Mithieux and Rousset (1989) J. Biol. Chem. 264, 4664-4668]. This protein exhibited the expected properties for mediating the ATP-dependent association of vesicles with microtubules [Mithieux, Audebet and Rousset (1988) Biochim. Biophys. Acta 969, 121-130]. The 50 kDa membrane protein (MP50), initially extracted in very low amount from isolated pig thyroid lysosomes/endosomes, has now been purified from membrane preparations of crude vesicle fractions from pig liver and brain. MP50 was isolated from detergent-solubilized membrane protein by affinity chromatography on immobilized ATP; 3-5 mg of MP50 was obtained from 100 g of liver tissue. Phase partitioning in Triton X-114 indicated that MP50 is a peripheral membrane protein. Radioiodinated liver MP50 bound to microtubules assembled in vitro. The binding was inhibited by ATP (Ki = 0.76 mM) and displaced by unlabelled liver or brain MP50. Equilibrium binding studies yielded KD values of 1.8 x 10(-7) M. By N-terminal amino acid sequence analysis, MP50 was identified as glutamate dehydrogenase (GDH), by comparison of V8 protease peptide maps of MP50 with purified liver GDH. Liver MP50 exhibited a low GDH activity; 4-5 units/mg compared with 18 and 34 units/mg for purified bovine and rat liver GDH respectively. Bovine and rat liver GDH yielded six spots from pI 5.7 to 7.2 when analysed by two-dimensional electrophoresis; in contrast, MP50 gave one main spot (corresponding to spot 2 of liver GDH) with a pI of approx. 6.5. Soluble liver GDH from commercial sources exhibited a very low or no microtubule-binding activity. In conclusion, we have found a membrane-bound form of GDH capable of specific and nucleotide-sensitive interaction with microtubules. Our data suggest that GDH isoproteins, the number of which has been undervalued up to now, could have cellular functions other than that of an enzyme. Images Figure 1 Figure 3

  5. STEREOLOGICAL ESTIMATES OF THE BASAL FOREBRAIN CELL POPULATION IN THE RAT, INCLUDING NEURONS CONTAINING CHOLINE ACETYLTRANSFERASE (ChAT), GLUTAMIC ACID DECARBOXYLASE (GAD) OR PHOSPHATE-ACTIVATED GLUTAMINASE (PAG) AND COLOCALIZING VESICULAR GLUTAMATE TRANSPORTERS (VGluTs)

    PubMed Central

    GRITTI, I.; HENNY, P.; GALLONI, F.; MAINVILLE, L.; MARIOTTI, M.; JONES, B. E.

    2006-01-01

    The basal forebrain (BF) plays an important role in modulating cortical activity and influencing attention, learning and memory. These activities are fulfilled importantly yet not entirely by cholinergic neurons. Noncholinergic neurons also contribute and are comprised by GABAergic neurons and other possibly glutamatergic neurons. The aim of the present study was to estimate the total number of cells in the BF of the rat and the proportions of that total represented by cholinergic, GABAergic and glutamatergic neurons. For this purpose, cells were counted using unbiased stereological methods within the medial septum, diagonal band, magnocellular preoptic nucleus, substantia innominata and globus pallidus in sections stained for Nissl substance and/or the neurotransmitter enzymes, choline acetyltransferase (ChAT), glutamic acid decarboxylase (GAD) or phosphate-activated glutaminase (PAG). In Nissl-stained sections, the total number of neurons in the BF was estimated as ~355,000 and the numbers of ChAT-immuno-positive (+) as ~22,000, GAD+ ~119,000 and PAG+ ~316,000, corresponding to ~5%, ~35% and ~90% of the total. Thus, of the large population of BF neurons, only a small proportion has the capacity to synthesize acetylcholine (ACh), one third to synthesize GABA and the vast majority to synthesize glutamate (Glu). Moreover, through the presence of PAG, a proportion of ACh- and GABA-synthesizing neurons also have the capacity to synthesize Glu. In sections dual fluorescent immunostained for vesicular transporters, VGluT3 and not VGluT2 was present in the cell bodies of most PAG+ and ChAT+ and half the GAD+ cells. Given previous results showing that VGluT2 and not VGluT3 was present in BF axon terminals and not colocalized with VAChT or VGAT, we conclude that the BF cell population influences cortical and subcortical regions through neurons which release ACh, GABA or Glu from their terminals but which in part can also synthesize and release Glu from their soma or

  6. Evaluation of copper-dependent proteasome-inhibitory and apoptosis-inducing activities of novel pyrrolidine dithiocarbamate analogues.

    PubMed

    Yu, Zhiyong; Wang, Fei; Milacic, Vesna; Li, Xiaofeng; Cui, Qiuzhi Cindy; Zhang, Bin; Yan, Bing; Dou, Q Ping

    2007-12-01

    Apoptosis has a central role in the pathogenesis of many human diseases, one of which is cancer. One of the most important strategies to regulate apoptosis is via the ubiquitin-proteasome pathway. It has been shown that inhibition of proteasomal chymotrypsin-like activity is a strong apoptosis-inducing stimulus and that actively proliferating cancer cells are more sensitive to proteasome inhibitors than normal or untransformed cells. Dithioscarbamates are a class of metal-chelating compounds with various applications in medicine. We reported previously that certain members of dithiocarbamates, such as pyrrolidine dithiocarbamate (PDTC), diethyldithiocarbamate and disulfiram, are able to bind with tumor cellular copper, forming an active complex with proteasome-inhibitory, apoptosis-inducing and anti-cancer activities. In the current study, we synthesized eight PDTC analogues with substitutions made to the pyrrolidine ring and studied their structure-activity relationships. We found that substitution of the pyrrolidine ring with piperidine had almost no effect on their proteasome-inhibitory and anti-proliferative potencies in human breast cancer cells. However, after the pyrrolidine ring was substituted with morpholine, the activity of the mixtures slightly decreased but was completely lost when piperazine with the attached ethyl group was used for the substitution. This structure-activity relationship was confirmed by the results generated with the corresponding copper complexes. Our data further support the novel concept of using accumulated copper in human cancer cells as a selective approach for chemotherapy. PMID:17982703

  7. Chiral Effect of a Phe Residue in Position 3 of the Dmt(1)-L(or D)-Tic(2) Analogues on Opioid Functional Activities.

    PubMed

    Lee, Yeon Sun; Qu, Hong Chang; Davis, Peg; Ma, Shou-Wu; Vardanyan, Ruben; Lai, Josephine; Porreca, Frank; Hruby, Victor J

    2013-07-11

    In this letter, we describe a structure-activity relationships study, specifically related to the chirality of third amino acid residue in our H-Dmt-L(or D)-Tic analogues, of which C-terminus is attached to a piperidinyl moiety. Observed selectivities and functional activities of these analogues demonstrated that the chiralities of the second and third position residues are crucial for determining whether these ligands act as antagonists or agonists at the δ opioid receptor, but not at the μ opioid receptor.

  8. Synthesis of strigolactones analogues by intramolecular [2+2] cycloaddition of ketene-iminium salts to olefins and their activity on Orobanche cumana seeds.

    PubMed

    Lachia, Mathilde; Wolf, Hanno Christian; De Mesmaeker, Alain

    2014-05-01

    Strigolactones have been the latest identified phytohormones. Among the strigolactones analogues described recently, GR-24 remains the most studied derivative which is used as standard in this field. In order to improve several properties of GR-24 for potential agronomical applications, we investigated the effect of substituents on the B and C-rings on the activity for seed germination induction. We report here the synthesis of 9 GR-24 analogues via a [2+2] intramolecular cycloaddition of ketene-iminium salts and a summary of their activity for the germination of Orobanche cumana (broomrape) seeds.

  9. Vesicular glutamate transporter 2 is required for the respiratory and parasympathetic activation produced by optogenetic stimulation of catecholaminergic neurons in the rostral ventrolateral medulla of mice in vivo.

    PubMed

    Abbott, Stephen B G; Holloway, Benjamin B; Viar, Kenneth E; Guyenet, Patrice G

    2014-01-01

    Catecholaminergic neurons of the rostral ventrolateral medulla (RVLM-CA neurons; C1 neurons) contribute to the sympathetic, parasympathetic and neuroendocrine responses elicited by physical stressors such as hypotension, hypoxia, hypoglycemia, and infection. Most RVLM-CA neurons express vesicular glutamate transporter (VGLUT)2, and may use glutamate as a ionotropic transmitter, but the importance of this mode of transmission in vivo is uncertain. To address this question, we genetically deleted VGLUT2 from dopamine-β-hydroxylase-expressing neurons in mice [DβH(Cre/0) ;VGLUT2(flox/flox) mice (cKO mice)]. We compared the in vivo effects of selectively stimulating RVLM-CA neurons in cKO vs. control mice (DβH(Cre/0) ), using channelrhodopsin-2 (ChR2-mCherry) optogenetics. ChR2-mCherry was expressed by similar numbers of rostral ventrolateral medulla (RVLM) neurons in each strain (~400 neurons), with identical selectivity for catecholaminergic neurons (90-99% colocalisation with tyrosine hydroxylase). RVLM-CA neurons had similar morphology and axonal projections in DβH(Cre/0) and cKO mice. Under urethane anesthesia, photostimulation produced a similar pattern of activation of presumptive ChR2-positive RVLM-CA neurons in DβH(Cre/0) and cKO mice. Photostimulation in conscious mice produced frequency-dependent respiratory activation in DβH(Cre/0) mice but no effect in cKO mice. Similarly, photostimulation under urethane anesthesia strongly activated efferent vagal nerve activity in DβH(Cre/0) mice only. Vagal responses were unaffected by α1 -adrenoreceptor blockade. In conclusion, two responses evoked by RVLM-CA neuron stimulation in vivo require the expression of VGLUT2 by these neurons, suggesting that the acute autonomic responses driven by RVLM-CA neurons are mediated by glutamate.

  10. Itraconazole Side Chain Analogues: Structure–Activity Relationship Studies for Inhibition of Endothelial Cell Proliferation, Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) Glycosylation, and Hedgehog Signaling

    PubMed Central

    Shi, Wei; Nacev, Benjamin A.; Aftab, Blake T.; Head, Sarah; Rudin, Charles M.; Liu, Jun O.

    2012-01-01

    Itraconazole is an antifungal drug that was recently found to possess potent antiangiogenic activity and anti-hedgehog (Hh) pathway activity. To search for analogues of itraconazole with greater potency and to understand the structure–activity relationship in both antiangiogenic and Hh targeting activity, 25 itraconazole side chain analogues were synthesized and assayed for inhibition of endothelial cell proliferation and Gli1 transcription in a medulloblastoma (MB) culture. Through this analysis, we have identified analogues with increased potency for inhibiting endothelial cell proliferation and the Hh pathway, as well as VEGFR2 glycosylation that was recently found to be inhibited by itraconazole. An SAR analysis of these activities revealed that potent activity of the analogues against VEGFR2 glycosylation was generally driven by side chains of at least four carbons in composition with branching at the α or β position. SAR trends for targeting the Hh pathway were divergent from those related to HUVEC proliferation or VEGFR2 glycosylation. These results also suggest that modification of the sec-butyl side chain can lead to enhancement of the biological activity of itraconazole. PMID:21936514

  11. Spontaneous L-glutamate release enhancement in rat substantia gelatinosa neurons by (-)-carvone and (+)-carvone which activate different types of TRP channel.

    PubMed

    Kang, Qin; Jiang, Chang-Yu; Fujita, Tsugumi; Kumamoto, Eiichi

    2015-04-10

    Transient receptor potential (TRP) channels in the spinal dorsal horn lamina II (substantia gelatinosa; SG), which are involved in the modulation of nociceptive transmission, have not yet been fully examined in property. Activation of the TRP channels by various plant-derived chemicals results in an increase in the spontaneous release of L-glutamate onto the SG neurons. We examined the effects of a monoterpene ketone (-)-carvone (contained in spearmint) and its stereoisomer (+)-carvone (in caraway) on glutamatergic spontaneous excitatory transmission in SG neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. (-)-Carvone and (+)-carvone increased the frequency of spontaneous excitatory postsynaptic current (sEPSC) in a reversible and concentration-dependent manner with a small increase in its amplitude. Half-maximal effective concentrations of (-)-carvone and (+)-carvone in increasing sEPSC frequency were 0.70 mM and 0.72 mM, respectively. The (-)-carvone but not (+)-carvone activity was inhibited by a TRPV1 antagonist capsazepine. On the other hand, the (+)-carvone but not (-)-carvone activity was inhibited by a TRPA1 antagonist HC-030031. These results indicate that (-)-carvone and (+)-carvone activate TRPV1 and TRPA1 channels, respectively, resulting in an increase in spontaneous L-glutamate release onto SG neurons, with almost the same efficacy. Such a difference in TRP activation between the stereoisomers may serve to know the properties of TRP channels in the SG. PMID:25747716

  12. Redox Activity of Copper(II) Complexes with NSFRY Pentapeptide and Its Analogues

    PubMed Central

    Wiloch, Magdalena Zofia; Wawrzyniak, Urszula Elżbieta; Ufnalska, Iwona; Piotrowski, Grzegorz; Bonna, Arkadiusz; Wróblewski, Wojciech

    2016-01-01

    The influence of cation-π interactions on the electrochemical properties of copper(II) complexes with synthesized pentapeptide C-terminal fragment of Atrial Natriuretic Factor (ANF) hormone was studied in this work. Molecular modeling performed for Cu(II)-NSFRY-NH2 complex indicated that the cation-π interactions between Tyr and Cu(II), and also between Phe-Arg led to specific conformation defined as peptide box, in which the metal cation is isolated from the solvent by peptide ligand. Voltammetry experiments enabled to compare the redox properties and stability of copper(II) complexes with NSFRY-NH2 and its analogues (namely: NSFRA-NH2, NSFRF-NH2, NSAAY-NH2, NSAAA-NH2, AAAAA-NH2) as well as to evaluate the contribution of individual amino acid residues to these properties. The obtained results led to the conclusion, that cation-π interactions play a crucial role in the effective stabilization of copper(II) complexes with the fragments of ANF peptide hormone and therefore could control the redox processes in other metalloproteins. PMID:27517864

  13. Redox Activity of Copper(II) Complexes with NSFRY Pentapeptide and Its Analogues.

    PubMed

    Wiloch, Magdalena Zofia; Wawrzyniak, Urszula Elżbieta; Ufnalska, Iwona; Piotrowski, Grzegorz; Bonna, Arkadiusz; Wróblewski, Wojciech

    2016-01-01

    The influence of cation-π interactions on the electrochemical properties of copper(II) complexes with synthesized pentapeptide C-terminal fragment of Atrial Natriuretic Factor (ANF) hormone was studied in this work. Molecular modeling performed for Cu(II)-NSFRY-NH2 complex indicated that the cation-π interactions between Tyr and Cu(II), and also between Phe-Arg led to specific conformation defined as peptide box, in which the metal cation is isolated from the solvent by peptide ligand. Voltammetry experiments enabled to compare the redox properties and stability of copper(II) complexes with NSFRY-NH2 and its analogues (namely: NSFRA-NH2, NSFRF-NH2, NSAAY-NH2, NSAAA-NH2, AAAAA-NH2) as well as to evaluate the contribution of individual amino acid residues to these properties. The obtained results led to the conclusion, that cation-π interactions play a crucial role in the effective stabilization of copper(II) complexes with the fragments of ANF peptide hormone and therefore could control the redox processes in other metalloproteins. PMID:27517864

  14. Synthesis and structure/antioxidant activity relationship of novel catecholic antioxidant structural analogues to hydroxytyrosol and its lipophilic esters.

    PubMed

    Bernini, Roberta; Crisante, Fernanda; Barontini, Maurizio; Tofani, Daniela; Balducci, Valentina; Gambacorta, Augusto

    2012-08-01

    A large panel of novel catecholic antioxidants and their fatty acid or methyl carbonate esters has been synthesized in satisfactory to good yields through a 2-iodoxybenzoic acid (IBX)-mediated aromatic hydroxylation as the key step. The new catechols are structural analogues of naturally occurring hydroxytyrosol (3,4-DHE). To evaluate structure/activity relationships, the antioxidant properties of all catecholic compounds were evaluated in vitro by ABTS assay and on whole cells by DCF fluorometric assay and compared with that of the corresponding already known hydroxytyrosyl derivatives. Results outline that all of the new catechols show antioxidant capacity in vitro higher than that of the corresponding hydroxytyrosyl derivatives. Less evident positive effects have been detected in whole cells experiments. Cytotoxicity experiments, using MTT assay, on a representative set of compounds evidenced no influence in cell survival.

  15. Teratogen metabolism: spontaneous decay hydrolysis products of thalidomide and thalidomide analogue are not activated by liver microsomes

    SciTech Connect

    Braun, A.G.; Weinreb, S.L.

    1983-01-01

    Thalidomide and two analogues, EM87 and EM12, inhibit the attachment of tumor cells to concanavalin A coated surfaces only if the drugs are treated with hepatic microsomes and cofactors. Pre-incubation of these drugs in buffered saline at 37 C results in a progressive decline in their ability to be activated to inhibitory products. Similarly, post-incubation of the inhibitory products leads to a decline in their ability to inhibit attachment. Decay rates differ for the three compounds. Thalidomide, EM87 and EM12 require 3 hours, 1 hour and 6 hours, respectively, to decline to control levels. These relative rates of decay are consistent with the relative teratogenicity of the three drugs.

  16. Identification of novel mureidomycin analogues via rational activation of a cryptic gene cluster in Streptomyces roseosporus NRRL 15998

    PubMed Central

    Jiang, Lingjuan; Wang, Lu; Zhang, Jihui; Liu, Hao; Hong, Bin; Tan, Huarong; Niu, Guoqing

    2015-01-01

    Antimicrobial agents are urgently needed to tackle the growing threat of antibiotic-resistant pathogens. An important source of new antimicrobials is the large repertoire of cryptic gene clusters embedded in microbial genomes. Genome mining revealed a napsamycin/mureidomycin biosynthetic gene cluster in the chromosome of Streptomyces roseosporus NRRL 15998. The cryptic gene cluster was activated by constitutive expression of a foreign activator gene ssaA from sansanmycin biosynthetic gene cluster of Streptomyces sp. strain SS. Expression of the gene cluster was verified by RT-PCR analysis of key biosynthetic genes. The activated metabolites demonstrated potent inhibitory activity against the highly refractory pathogen Pseudomonas aeruginosa, and characterization of the metabolites led to the discovery of eight acetylated mureidomycin analogues. To our surprise, constitutive expression of the native activator gene SSGG_02995, a ssaA homologue in S. roseosporus NRRL 15998, has no beneficial effect on mureidomycin stimulation. This study provides a new way to activate cryptic gene cluster for the acquisition of novel antibiotics and will accelerate the exploitation of prodigious natural products in Streptomyces. PMID:26370924

  17. Copper complexes of glycyl-histidyl-lysine and two of its synthetic analogues: chemical behaviour and biological activity.

    PubMed

    Conato, C; Gavioli, R; Guerrini, R; Kozlowski, H; Mlynarz, P; Pasti, C; Pulidori, F; Remelli, M

    2001-05-01

    Copper complex formation equilibria of glycyl-L-histidyl-L-lysine (Gly-His-Lys, GHK) and of two synthetic analogues, where the histidine residue was replaced with a synthetic amino acid (L-spinacine or L-1,2,3,4-tetrahydro-isoquinoline-3-carboxylic acid), have been carefully investigated using different experimental techniques: potentiometry, solution calorimetry, UV-VIS spectrophotometry, circular dichroism and electron paramagnetic resonance spectroscopies. All the ligands formed complexes having different stoichiometries and stabilities; evidence for the formation of binuclear species is also shown. The structures of the main complexes are discussed. It is suggested that the lateral lysine amino group participates in complex formation, but only at alkaline pH values: at physiological pH this group is protonated and available for possible interactions with cellular receptors. The above tripeptides have been tested for their enzymatic stability in human serum: the synthetic compounds showed no significant degradation for at least 3 h. Finally, their activity as growth factor has been studied in vitro. The two synthetic analogues showed an activity comparable to or even higher than that of GHK, thus suggesting their possible use as additives in cell culture media, even in the presence of serum. Relevant information on the GHK action mechanism as cell growth factor has been obtained: the formation of copper complexes, driven by the first (Gly) residue, appears necessary while the second residue (His) does not appear to play a specific role; the presence of the free side chain of the third residue (Lys) appears to be of fundamental importance. PMID:11325542

  18. Glutamate Receptor Stimulation Up-Regulates Glutamate Uptake in Human Müller Glia Cells.

    PubMed

    López-Colomé, Ana María; López, Edith; Mendez-Flores, Orquidia G; Ortega, Arturo

    2016-07-01

    Glutamate, the main excitatory amino acid in the vertebrate retina, is a well know activator of numerous signal transduction pathways, and has been critically involved in long-term synaptic changes acting through ionotropic and metabotropic glutamate receptors. However, recent findings underlining the importance of intensity and duration of glutamate stimuli for specific neuronal responses, including excitotoxicity, suggest a crucial role for Na(+)-dependent glutamate transporters, responsible for the removal of this neurotransmitter from the synaptic cleft, in the regulation of glutamate-induced signaling. Transporter proteins are expressed in neurons and glia cells, albeit most of glutamate uptake occurs in the glial compartment. Within the retina, Müller glia cells are in close proximity to glutamatergic synapses and participate in the recycling of glutamate through the glutamate/glutamine shuttle. In this context, we decided to investigate a plausible role of glutamate as a regulatory signal for its own transport in human retinal glia cells. To this end, we determined [(3)H]-D-aspartate uptake in cultures of spontaneously immortalized human Müller cells (MIO-M1) exposed to distinct glutamatergic ligands. A time and dose-dependent increase in the transporter activity was detected. This effect was dependent on the activation of the N-methyl D-aspartate subtype of glutamate receptors, due to a dual effect: an increase in affinity and an augmented expression of the transporter at the plasma membrane, as established via biotinylation experiments. Furthermore, a NMDA-dependent association of glutamate transporters with the cystoskeletal proteins ezrin and glial fibrillary acidic protein was also found. These results add a novel mediator of the glutamate transporter modulation and further strengthen the notion of the critical involvement of glia cells in synaptic function. PMID:27017513

  19. Modulation of glutamatergic transmission by metabotropic glutamate receptor activation in second-order neurons of the guinea pig nucleus tractus solitarius.

    PubMed

    Ohi, Yoshiaki; Kimura, Satoko; Haji, Akira

    2014-09-18

    Activity of second-order relay neurons in the nucleus tractus solitarius (NTS) is regulated by peripheral and intrinsic synaptic inputs, and modulation of those inputs by metabotropic glutamate receptors (mGluRs) has been proposed. This study investigated effects of mGluR activation on glutamatergic transmission in the NTS second-order neurons of guinea pigs. Whole-cell patch-clamp recordings from the brainstem slices revealed that activation of mGluRs exerted its effects on the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) but not on the amplitude. The sEPSC frequency was increased by an agonist of group I mGluRs, and it was decreased by an mGluR1 antagonist but not by an mGluR5 antagonist. The agonists of group II and III mGluRs decreased the sEPSC frequency, while their antagonists alone had no effect. Perfusion of cystine or TBOA, either of which elevates extracellular glutamate concentration, resulted in an increase in the sEPSC frequency, leaving the amplitude unchanged. The increased frequency of sEPSCs was returned to control by an mGluR1 antagonist. The tractus solitarius-evoked EPSCs were not altered by an agonist of group I mGluRs, whereas they were decreased along with an increase in paired-pulse ratio by agonists of group II and III mGluRs. These results suggest that mGluRs are present at the presynaptic sites in the NTS second-order neurons in guinea pigs. The mGluR1s function to facilitate the release of glutamate from axon terminals of intrinsic interneurons and the group II and III mGluRs play an inhibitory role in glutamatergic transmission.

  20. Biodegradable analogues of DDT*

    PubMed Central

    Metcalf, Robert L.; Kapoor, Inder P.; Hirwe, Asha S.

    1971-01-01

    Despite the immense utility of DDT for vector control its usefulness is prejudiced by its stability in the environment and by the low rate at which it can be degraded biologically. Metabolic studies in insects, in mice, and in a model ecosystem with several food chains have shown that DDT analogues with substituent groups readily attacked by multifunction oxidases undergo a substantial degree of biological degradation and do not appear to be stored readily in animal tissues or concentrated in food chains. Detailed metabolic pathways have been worked out and it is clear that comparative biochemistry can be used to develop DDT analogues that are adequately persistent yet biodegradable. A number of new DDT analogues have been evaluated for insecticidal activity against flies and mosquitos and for their potential usefulness as safe, persistent, and biodegradable insecticides. PMID:5315354

  1. Synergistic activities of a silver(I) glutamic acid complex and reactive oxygen species (ROS): a novel antimicrobial and chemotherapeutic agent.

    PubMed

    Batarseh, K I; Smith, M A

    2012-01-01

    The antimicrobial and chemotherapeutic activities of a silver(I) glutamic acid complex with the synergistic concomitant generation of reactive oxygen species (ROS) were investigated here. The ROS generation system employed was via Fenton chemistry. The antimicrobial and chemotherapeutic activities were investigated on Staphylococcus aureus ATCC 43300 and Escherichia coli bacteria, and Vero and MCF-7 tumor cell lines, respectively. Antimicrobial activities were conducted by determining minimum inhibitory concentration (MIC), while chemotherapeutic efficacies were done by serial dilution using standard techniques to determine the half maximal inhibitory concentration (IC50). The antimicrobial and chemotherapeutic results obtained were compared with positive control drugs gentamicin, oxacillin, penicillin, streptomycin and cisplatin, a ubiquitously used platinum-based antitumor drug, and with the silver(I) glutamic acid complex and hydrogen peroxide separately. Based on MIC and IC50 values, it was determined that this synergistic approach was very effective at extremely low concentrations, especially when compared with the other drugs evaluated here. This finding might be of great significance regarding metronomic dosing when this synergistic approach is clinically implemented. Since silver at low concentrations exhibits no toxic, mutagenic and carcinogenic activities, this might offer an alternative approach for the development of safer silver-based antimicrobial and chemotherapeutic drugs, thereby reducing or even eliminating the toxicity associated with current drugs. Accordingly, the present approach might be integrated into the systemic clinical treatment of infectious diseases and cancer. PMID:22680634

  2. Probing the Active Center of Benzaldehyde Lyase with Substitutions and the Pseudosubstrate Analogue Benzoylphosphonic Acid Methyl Ester

    SciTech Connect

    Brandt, Gabriel S.; Nemeria, Natalia; Chakraborty, Sumit; McLeish, Michael J.; Yep, Alejandra; Kenyon, George L.; Petsko, Gregory A.; Jordan, Frank; Ringe, Dagmar

    2008-07-28

    Benzaldehyde lyase (BAL) catalyzes the reversible cleavage of (R)-benzoin to benzaldehyde utilizing thiamin diphosphate and Mg{sup 2+} as cofactors. The enzyme is important for the chemoenzymatic synthesis of a wide range of compounds via its carboligation reaction mechanism. In addition to its principal functions, BAL can slowly decarboxylate aromatic amino acids such as benzoylformic acid. It is also intriguing mechanistically due to the paucity of acid-base residues at the active center that can participate in proton transfer steps thought to be necessary for these types of reactions. Here methyl benzoylphosphonate, an excellent electrostatic analogue of benzoylformic acid, is used to probe the mechanism of benzaldehyde lyase. The structure of benzaldehyde lyase in its covalent complex with methyl benzoylphosphonate was determined to 2.49 {angstrom} (Protein Data Bank entry 3D7K) and represents the first structure of this enzyme with a compound bound in the active site. No large structural reorganization was detected compared to the complex of the enzyme with thiamin diphosphate. The configuration of the predecarboxylation thiamin-bound intermediate was clarified by the structure. Both spectroscopic and X-ray structural studies are consistent with inhibition resulting from the binding of MBP to the thiamin diphosphate in the active centers. We also delineated the role of His29 (the sole potential acid-base catalyst in the active site other than the highly conserved Glu50) and Trp163 in cofactor activation and catalysis by benzaldehyde lyase.

  3. Synthesis and Antitumor Activity of 1,5-Disubstituted 1,2,4-Triazoles as Cis-Restricted Combretastatin Analogues

    PubMed Central

    Romagnoli, Romeo; Baraldi, Pier Giovanni; Cruz-Lopez, Olga; Lopez Cara, Carlota; Carrion, Maria Dora; Brancale, Andrea; Hamel, Ernest; Chen, Longchuan; Bortolozzi, Roberta; Basso, Giuseppe; Viola, Giampietro

    2010-01-01

    A series of 1-aryl-5-(3′,4′,5′-trimethoxyphenyl) derivatives and their related 1-(3′,4′,5′-trimethoxyphenyl)-5-aryl-1,2,4-triazoles, designed as cis-restricted combretastatin analogues, were synthesized and evaluated for antiproliferative activity, inhibitory effects on tubulin polymerization, cell cycle effects, and apoptosis induction. Their activity was greater than, or comparable with, that of the reference compound CA-4. Flow cytometry studies showed that HeLa and Jurkat cells treated with the most active compounds 4l and 4o were arrested in the G2/M phase of the cell cycle in a concentration dependent manner. This effect was accompanied by apoptosis of the cells, mitochondrial depolarization, generation of reactive oxygen species, activation of caspase-3, and PARP cleavage. Compound 4l was also shown to have potential antivascular activity, since it induced endothelial cell shape change in vitro and disrupted the sprouting of endothelial cells in the chick aortic ring assay. PMID:20420439

  4. Structure Activity Relationship and Mechanism of Action Studies of Manzamine Analogues for the Control of Neuroinflammation and Cerebral Infections

    PubMed Central

    Peng, Jiangnan; Kudrimoti, Sucheta; Prasanna, Sivaprakasam; Odde, Srinivas; Doerksen, Robert J.; Pennaka, Hari K; Choo, Yeun-Mun; Rao, Karumanchi V.; Tekwani, Babu L.; Madgula, Vamsi; Khan, Shabana I.; Wang, Bin; Mayer, Alejandro M. S.; Jacob, Melissa R.; Tu, Lan Chun; Gertsch, Jürg; Hamann, Mark T.

    2010-01-01

    Structure-activity relationship studies were carried out by chemical modification of manzamine A (1), 8-hydroxymanzamine A (2), manzamine F (14), and ircinol isolated from the sponge Acanthostrongylophora. The derived analogues were evaluated for antimalarial, antimicrobial, and antineuroinflammatory activities. Several modified products exhibited potent and improved in vitro antineuroinflammatory, antimicrobial, and antimalarial activity. 1 showed improved activity against malaria compared to chloroquine in both multi- and single-dose in vivo experiments. The significant antimalarial potential was revealed by a 100% cure rate of malaria in mice with one administration of 100 mg/kg of 1. The potent antineuroinflammatory activity of the manzamines will provide great benefit for the prevention and treatment of cerebral infections (e.g. Cryptococcus and Plasmodium). In addition, 1 was shown to permeate across the blood-brain barrier (BBB) in an in vitro model using a MDR-MDCK monolayer. Docking studies support that 2 binds to the ATP-noncompetitive pocket of glycogen synthesis kinase-3β (GSK-3β), which is a putative target of manzamines. Based on the results presented here it will be possible to initiate rational drug design efforts around this natural product scaffold for the treatment of several different diseases. PMID:20017491

  5. Probing the active center of benzaldehyde lyase with substitutions and the pseudosubstrate analogue benzoylphosphonic acid methyl ester.

    PubMed

    Brandt, Gabriel S; Nemeria, Natalia; Chakraborty, Sumit; McLeish, Michael J; Yep, Alejandra; Kenyon, George L; Petsko, Gregory A; Jordan, Frank; Ringe, Dagmar

    2008-07-22

    Benzaldehyde lyase (BAL) catalyzes the reversible cleavage of ( R)-benzoin to benzaldehyde utilizing thiamin diphosphate and Mg (2+) as cofactors. The enzyme is important for the chemoenzymatic synthesis of a wide range of compounds via its carboligation reaction mechanism. In addition to its principal functions, BAL can slowly decarboxylate aromatic amino acids such as benzoylformic acid. It is also intriguing mechanistically due to the paucity of acid-base residues at the active center that can participate in proton transfer steps thought to be necessary for these types of reactions. Here methyl benzoylphosphonate, an excellent electrostatic analogue of benzoylformic acid, is used to probe the mechanism of benzaldehyde lyase. The structure of benzaldehyde lyase in its covalent complex with methyl benzoylphosphonate was determined to 2.49 A (Protein Data Bank entry 3D7K ) and represents the first structure of this enzyme with a compound bound in the active site. No large structural reorganization was detected compared to the complex of the enzyme with thiamin diphosphate. The configuration of the predecarboxylation thiamin-bound intermediate was clarified by the structure. Both spectroscopic and X-ray structural studies are consistent with inhibition resulting from the binding of MBP to the thiamin diphosphate in the active centers. We also delineated the role of His29 (the sole potential acid-base catalyst in the active site other than the highly conserved Glu50) and Trp163 in cofactor activation and catalysis by benzaldehyde lyase.

  6. Strigolactone analogues induce apoptosis through activation of p38 and the stress response pathway in cancer cell lines and in conditionally reprogramed primary prostate cancer cells.

    PubMed Central

    Pollock, Claire B; McDonough, Sara; Wang, Victor S.; Lee, Hyojung; Ringer, Lymor; Li, Xin; Prandi, Cristina; Lee, Richard J.; Feldman, Adam S.; Koltai, Hinanit; Kapulnik, Yoram; Rodriguez, Olga C; Schlegel, Richard; Albanese, Christopher; Yarden, Ronit I.

    2014-01-01

    Strigolactones are a novel class of plant hormones produced in roots and regulate shoot and root development. We have previously shown that synthetic strigolactone analogues potently inhibit growth of breast cancer cells and breast cancer stem cells. Here we show that strigolactone analogues inhibit the growth and survival of an array of cancer-derived cell lines representing solid and non-solid cancer cells including: prostate, colon, lung, melanoma, osteosarcoma and leukemic cell lines, while normal cells were minimally affected. Treatment of cancer cells with strigolactone analogues was hallmarked by activation of the stress-related MAPKs: p38 and JNK and induction of stress-related genes; cell cycle arrest and apoptosis evident by increased percentages of cells in the sub-G1 fraction and Annexin V staining. In addition, we tested the response of patient-matched conditionally reprogrammed primary prostate normal and cancer cells. The tumor cells exhibited significantly higher sensitivity to the two most potent SL analogues with increased apoptosis confirmed by PARP1 cleavage compared to their normal counterpart cells. Thus, Strigolactone analogues are promising candidates for anticancer therapy by their ability to specifically induce cell cycle arrest, cellular stress and apoptosis in tumor cells with minimal effects on growth and survival of normal cells. PMID:24742967

  7. A feasible approach to evaluate the relative reactivity of NHS-ester activated group with primary amine-derivatized DNA analogue and non-derivatized impurity.

    PubMed

    Dou, Shuping; Virostko, John; Greiner, Dale L; Powers, Alvin C; Liu, Guozheng

    2015-01-01

    Synthetic DNA analogues with improved stability are widely used in life science. The 3'and/or 5' equivalent terminuses are often derivatized by attaching an active group for further modification, but a certain amount of non-derivatized impurity often remains. It is important to know to what extent the impurity would influence further modification. The reaction of an NHS ester with primary amine is one of the most widely used options to modify DNA analogues. In this short communication, a 3'-(NH2-biotin)-derivatized morpholino DNA analogue (MORF) was utilized as the model derivatized DNA analogue. Inclusion of a biotin concomitant with the primary amine at the 3'-terminus allows for the use of streptavidin to discriminate between the products from the derivatized MORF and non-derivatized MORF impurity. To detect the MORF reaction with NHS ester, S-acetyl NHS-MAG3 was conjugated to the DNA analogue for labeling with (99m)Tc, a widely used nuclide in the clinic. It was found that the non-derivatized MORF also reacted with the S-acetyl NHS-MAG3. Radiolabeling of the product yielded an equally high labeling efficiency. Nevertheless, streptavidin binding indicated that under the conditions of this investigation, the non-derivatized MORF was five times less reactive than the amine-derivatized MORF. PMID:25621701

  8. A FEASIBLE APPROACH TO EVALUATE THE RELATIVE REACTIVITY OF NHS-ESTER ACTIVATED GROUP WITH PRIMARY AMINE-DERIVATIZED DNA ANALOGUE AND NON-DERIVATIZED IMPURITY

    PubMed Central

    Dou, Shuping; Virostko, John; Greiner, Dale L.; Powers, Alvin C.; Liu, Guozheng

    2015-01-01

    Synthetic DNA analogues with improved stability are widely used in life science. The 3′ and/or 5′ equivalent terminuses are often derivatized by attaching an active group for further modification, but a certain amount of non-derivatized impurity often remains. It is important to know to what extent the impurity would influence further modification. The reaction of an NHS ester with primary amine is one of the most widely used options to modify DNA analogues. In this short communication, a 3′-(NH2-biotin)-derivatized morpholino DNA analogue (MORF) was utilized as the model derivatized DNA analogue. Inclusion of a biotin concomitant with the primary amine at the 3′-terminus allows for the use of streptavidin to discriminate between the products from the derivatized MORF and non-derivatized MORF impurity. To detect the MORF reaction with NHS ester, S-acetyl NHS-MAG3 was conjugated to the DNA analogue for labeling with 99mTc, a widely used nuclide in the clinic. It was found that the non-derivatized MORF also reacted with the S-acetyl NHS-MAG3. Radiolabeling of the product yielded an equally high labeling efficiency. Nevertheless, streptavidin binding indicated that under the conditions of this investigation, the non-derivatized MORF was five times less reactive than the amine-derivatized MORF. PMID:25621701

  9. Differential modulation of IgE-dependent activation of human basophils by ambroxol and related secretolytic analogues.

    PubMed

    Gibbs, B F

    2009-01-01

    Ambroxol is a widely used secretolytic agent originally developed from vasicine, a natural alkaloid found in Adhatoda vasica, extracts of which have been used to treat bronchitis, asthma, and rheumatism. We previously reported that ambroxol inhibits IgE-dependent mediator secretion from human mast cells and basophils, key effector cells of allergic inflammation. Here, the mechanisms involved in the inhibitory properties of ambroxol were assessed in comparison to other secretolytic analogues (e.g. vasicine, bromhexine, sputolysin). The results show that, in comparison to ambroxol, which reduced IgE-dependent histamine release from basophils at 10 microM-1 mM, the release of the amine was only moderately reduced by sputolysin and vasicine at 1 mM. In contrast, above 10 microM, bromhexine was found to be toxic to basophils in vitro as evidenced by induction of histamine release and reduced cell viability. In contrast, the inhibitory actions of ambroxol at concentrations below 1 mM were not toxic and entirely reversible. Ambroxol was also more potent than either sputolysin or vasicine in attenuating basophil IL-4 and IL-13 secretions, whereas bromhexine-induced suppression of de novo cytokine synthesis was due to toxic effects. Additionally, ambroxol reduced IgE-dependent p38 MAPK phosphorylation in basophils, unlike bromhexine, sputolysin and vasicine. These results clearly show that ambroxol is both more potent and effective at inhibiting IgE-dependent basophil mediator release and p38 MAPK activity than the other secretolytic analogues employed. The therapeutic potential of ambroxol as an anti-allergic agent is further underlined by these data.

  10. Larvicidal activity and structure activity relationship of cinnamoyl amides from Zanthoxylum armatum and their synthetic analogues against diamondback moth, Plutella xylostella

    PubMed Central

    Kumar, Vishal; Reddy, S. G. Eswara; Bhardwaj, Anuja; Dolma, Shudh Kirti; Kumar, Neeraj

    2016-01-01

    Cinnamoyl amides isolated from Zanthoxylum armatum (Rutaceae) and their synthetic analogues were tested for their insecticidal activity against the second instar larvae of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) to determine the promising structures with insecticidal activity. Most of the test compounds showed promising activity against larvae of P. xylostella. However, the activities of different compounds varied depending on the presence of different substituents at various positions of both the aromatic rings A and B. Among the tested compounds, 8, N-(3-bromo-4-methoxyphenethyl)cinnamamide showed best larvicidal activity with an LC50 = 62.13 mg/L followed by 6, N-(3׳-bromophenethyl)cinnamamide (LC50=128.49 mg/L) and 2 N-(4׳-methoxyphenylethyl)cinnamamide (LC50 = 225.65 mg/L). PMID:27231477

  11. Effects of a metabotropic glutamate receptor subtype 7 negative allosteric modulator in the periaqueductal grey on pain responses and rostral ventromedial medulla cell activity in rat.

    PubMed

    Palazzo, Enza; Marabese, Ida; Luongo, Livio; Boccella, Serena; Bellini, Giulia; Giordano, Maria Elvira; Rossi, Francesca; Scafuro, Mariantonietta; Novellis, Vito de; Maione, Sabatino

    2013-09-03

    The metabotropic glutamate receptor 7 (mGluR7) negative allosteric modulator, 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazolo[4,5-c]pyridin-4(5H)-one (MMPIP), was locally microinjected into the ventrolateral periaqueductal gray (VL PAG) and the effect on pain responses in formalin and spare nerve injury (SNI) -induced neuropathic pain models was monitored in the rat. The activity of rostral ventromedial medulla (RVM) "pronociceptive" ON and "antinociceptive" OFF cells was also evaluated. Intra-VL PAG MMPIP blocked the first and second phase of nocifensive behaviour in the formalin pain model. MMPIP increased the tail flick latency and simultaneously increased the activity of the OFF cells while inhibiting that of ON cells in rats with SNI of the sciatic nerve. MMPIP failed to modify nociceptive responses and associated RVM ON and OFF cell activity in sham rats. An increase in mGluR7 gene, protein and staining, the latter being associated with vesicular glutamate transporter-positive profiles, has been found in the VL PAG in SNI rats. Blockade of mGluR7 within the VL PAG has an antinociceptive effect in formalin and neuropathic pain models. VL PAG mGluR7 blockade offers a target for dis-inhibiting the VL PAG-RVM pathway and silencing pain in inflammatory and neuropathic pain models.

  12. Activation of f-channels by cAMP analogues in macropatches from rabbit sino-atrial node myocytes.

    PubMed Central

    Bois, P; Renaudon, B; Baruscotti, M; Lenfant, J; DiFrancesco, D

    1997-01-01

    1. The action of the two diastereometric phosphorothioate derivatives of cAMP, Rp-cAMPs and Sp-cAMPs, was investigated on hyperpolarization-activated 'pacemaker' current (i(f)) recorded in inside-out macropatches from rabbit sino-atrial (SA) node myocytes. 2. When superfused on the intracellular side of f-channels at the concentration of 10 microM, both cAMP derivatives accelerated i(f) activation; their action was moderately less pronounced than that due to the same concentration of cAMP. 3. The measurement of the i(f) conductance-voltage relation by voltage ramp protocols indicated that both cAMP analogues shift the activation curve of i(f) to more positive voltages with no change in maximal (fully activated) conductance. 4. Dose-response relationships of the shift of the i(f) activation curve showed that both Rp-cAMPs and Sp-cAMPs act as agonists in the cAMP-dependent direct f-channel activation. Fitting data to the Hill equation resulted in maximal shifts of 9.6 and 9.5 mV, apparent dissociation constants of 0.82 and 5.4 microM, and Hill coefficients of 0.82 and 1.12 for Sp-cAMPs and Rp-cAMPs, respectively. 5. The activating action of Rp-cAMPs, a known antagonist of cAMP in the activation of cAMP-dependent protein kinase, confirms previously established evidence that f-channel activation does not involve phosphorylation. These results also suggest that the cAMP binding site of f-channels may be structurally similar to the cyclic nucleotide binding site of olfactory receptor channels. PMID:9218217

  13. Structure-In Vitro Activity Relationships of Pentamidine Analogues and Dication-Substituted Bis-Benzimidazoles as New Antifungal Agents

    PubMed Central

    Del Poeta, Maurizio; Schell, Wiley A.; Dykstra, Christine C.; Jones, Susan; Tidwell, Richard R.; Czarny, Agnieszka; Bajic, Miroslav; Bajic, Marina; Kumar, Arvind; Boykin, David; Perfect, John R.

    1998-01-01

    Twenty analogues of pentamidine, 7 primary metabolites of pentamidine, and 30 dicationic substituted bis-benzimidazoles were screened for their inhibitory and fungicidal activities against Candida albicans and Cryptococcus neoformans. A majority of the compounds had MICs at which 80% of the strains were inhibited (MIC80s) comparable to those of amphotericin B and fluconazole. Unlike fluconazole, many of these compounds were found to have potent fungicidal activity. The most potent compound against C. albicans had an MIC80 of ≤0.09 μg/ml, and the most potent compound against C. neoformans had an MIC80 of 0.19 μg/ml. Selected compounds were also found to be active against Aspergillus fumigatus, Fusarium solani, Candida species other than C. albicans, and fluconazole-resistant strains of C. albicans and C. neoformans. It is clear from the data presented here that further studies on the structure-activity relationships, mechanisms of action and toxicities, and in vivo efficacies of these compounds are warranted to determine their clinical potential. PMID:9756747

  14. Modes of glutamate receptor gating

    PubMed Central

    Popescu, Gabriela K

    2012-01-01

    Abstract The time course of excitatory synaptic currents, the major means of fast communication between neurons of the central nervous system, is encoded in the dynamic behaviour of post-synaptic glutamate-activated channels. First-pass attempts to explain the glutamate-elicited currents with mathematical models produced reaction mechanisms that included only the most basic functionally defined states: resting vs. liganded, closed vs. open, responsive vs. desensitized. In contrast, single-molecule observations afforded by the patch-clamp technique revealed an unanticipated kinetic multiplicity of transitions: from microseconds-lasting flickers to minutes-long modes. How these kinetically defined events impact the shape of the synaptic response, how they relate to rearrangements in receptor structure, and whether and how they are physiologically controlled represent currently active research directions. Modal gating, which refers to the slowest, least frequently observed ion-channel transitions, has been demonstrated for representatives of all ion channel families. However, reaction schemes have been largely confined to the short- and medium-range time scales. For glutamate receptors as well, modal gating has only recently come under rigorous scrutiny. This article reviews the evidence for modal gating of glutamate receptors and the still developing hypotheses about the mechanism(s) by which modal shifts occur and the ways in which they may impact the time course of synaptic transmission. PMID:22106181

  15. Hydroxylated analogues of the orally active broad spectrum antifungal, Sch 51048 (1), and the discovery of posaconazole [Sch 56592; 2 or (S,S)-5].

    PubMed

    Bennett, Frank; Saksena, Anil K; Lovey, Raymond G; Liu, Yi-Tsung; Patel, Naginbhai M; Pinto, Patrick; Pike, Russel; Jao, Edwin; Girijavallabhan, Viyyoor M; Ganguly, Ashit K; Loebenberg, David; Wang, Haiyan; Cacciapuoti, Anthony; Moss, Eugene; Menzel, Fred; Hare, Roberta S; Nomeir, Amin

    2006-01-01

    As part of a detailed study, the syntheses, biological activities, and pharmacokinetic properties of hydroxylated analogues of the previously described broad spectrum antifungal agents, Sch 51048 (1), Sch 50001 (3), and Sch 50002 (4), are described. Based on an overall superior profile, one of the alcohols, Sch 56592 (2), was selected for clinical studies.

  16. Blockage of acquisition and expression of morphine-induced conditioned place preference in rats due to activation of glutamate receptors type II/III in nucleus accumbens.

    PubMed

    Baharlouei, Negar; Sarihi, Abdolrahman; Komaki, Alireza; Shahidi, Siamak; Haghparast, Abbas

    2015-08-01

    Numerous studies have shown that glutamate in the nucleus accumbens (NAc) is an essential neurotransmitter for the extension of morphine-induced place preference. mGlu2/3 glutamate receptors in the NAc have important roles in the reward pathway. However, less is known about the role of this glutamate receptor subtype in morphine-induced conditioned place preference (CPP). In this study, we examined the effects of bilateral intra-accumbal administration of LY379268, an mGlu2/3 receptor agonist on the acquisition and expression of morphine-induced CPP in rats. Adult male Wistar rats (n=136; 220-250g) were evaluated in a CPP paradigm. Doses of LY379268 (0.3, 1 and 3μg/0.5μL saline per side) were administered into the NAc on both sides during the 3days of the conditioning (acquisition) or post-conditioning (expression) phase. The results show that bilateral intra-accumbal administration of LY379268 (0.3, 1 and 3μg) markedly decreased the acquisition of morphine-induced CPP in a dose-dependent manner. In a second series of experiments, we determined that injection of LY379268 into the NAc considerably attenuated the expression of morphine CPP only at the highest dose (3μg). Our findings suggest that activation of mGlu2/3 receptors in the NAc dose-dependently blocked both the establishment and the maintenance of morphine-induced CPP and confirmed the role of this system as a potential therapeutic target for addiction.

  17. Gibbilimbol analogues as antiparasitic agents--Synthesis and biological activity against Trypanosoma cruzi and Leishmania (L.) infantum.

    PubMed

    Varela, Marina T; Dias, Roberto Z; Martins, Ligia F; Ferreira, Daiane D; Tempone, Andre G; Ueno, Anderson K; Lago, João Henrique G; Fernandes, João Paulo S

    2016-02-15

    The essential oils from leaves of Piper malacophyllum (Piperaceae) showed to be mainly composed by two alkenylphenol derivatives: gibbilimbols A and B. After isolation and structural characterization by NMR and MS data analysis, both compounds were evaluated against promastigote/amastigote forms of Leishmania (L.) infantum as well as trypomastigote/amastigote forms of Trypanosoma cruzi. The obtained results indicated that gibbilimbol B displayed potential against the tested parasites and low toxicity to mammalian cells, stimulating the preparation of several quite simple synthetic analogues in order to improve its activity and to explore the preliminary structure-activity relationships (SAR) data. Among the prepared derivatives, compound LINS03003 (n-octyl-4-hydroxybenzylamine) displayed the most potent IC50 values of 5.5 and 1.8 μM against amastigotes of T. cruzi and L. (L.) infantum, respectively, indicating higher activity than the natural prototype. In addition, this compound showed remarkable selectivity index (SI) towards the intracellular forms of Leishmania (SI=13.1) and T. cruzi (SI=4.3). Therefore, this work indicated that preparation of synthetic compounds structurally based in the bioactive natural products could be an interesting source of novel and selective compounds against these protozoan parasites. PMID:26821820

  18. Design and synthesis of conformationally constrained analogues of cis-cinnamic acid and evaluation of their plant growth inhibitory activity.

    PubMed

    Nishikawa, Keisuke; Fukuda, Hiroshi; Abe, Masato; Nakanishi, Kazunari; Tazawa, Yuta; Yamaguchi, Chihiro; Hiradate, Syuntaro; Fujii, Yoshiharu; Okuda, Katsuhiro; Shindo, Mitsuru

    2013-12-01

    1-O-cis-Cinnamoyl-β-D-glucopyranose is known to be one of the most potent allelochemical candidates and was isolated from Spiraea thunbergii Sieb by Hiradate et al. (2004), who suggested that it derived its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. In this study, key structural features and substituent effects of cis-cinnamic acid (cis-CA) on lettuce root growth inhibition was investigated. These structure-activity relationship studies indicated the importance of the spatial relationship of the aromatic ring and carboxylic acid moieties. In this context, conformationally constrained cis-CA analogues, in which the aromatic ring and cis-olefin were connected by a carbon bridge, were designed, synthesized, and evaluated as plant growth inhibitors. The results of the present study demonstrated that the inhibitory activities of the five-membered and six-membered bridged compounds were enhanced, up to 0.27 μM, and were ten times higher than cis-CA, while the potency of the other compounds was reduced.

  19. Opioids and efflux transporters. Part 4: influence of N-substitution on P-glycoprotein substrate activity of noroxymorphone analogues.

    PubMed

    Metcalf, Matthew D; Rosicky, Andrew D; Hassan, Hazem E; Eddington, Natalie D; Coop, Andrew; Cunningham, Christopher W; Mercer, Susan L

    2014-08-01

    The efflux transporter protein P-glycoprotein (P-gp) is capable of affecting the central distribution of diverse neurotherapeutics, including opioid analgesics, through their active removal from the brain. P-gp located at the blood brain barrier has been implicated in the development of tolerance to opioids and demonstrated to be up-regulated in rats tolerant to morphine and oxycodone. We have previously examined the influence of hydrogen-bonding oxo-substitutents on the P-gp-mediated efflux of 4,5-epoxymorphinan analgesics, as well as that of N-substituted analogues of meperidine. Structure-activity relationships (SAR) governing N-substituent effects on opioid efficacy is well-established, however the influence of such structural modifications on P-gp-mediated efflux is unknown. Here, we present SAR describing P-gp recognition of a short series of N-modified 4,5-epoxymorphinans. Oxymorphone, naloxone, naltrexone, and nalmexone all failed to demonstrate P-gp substrate activity, indicating these opioid scaffolds contain structural features that preclude recognition by the transporter. These results are examined using mathematical molecular modeling and discussed in comparison to other opioid scaffolds bearing similar N-substituents. PMID:24915880

  20. Larvicidal and Adulticidal Activity of Chroman and Chromene Analogues against Susceptible and Permethrin-Resistant Mosquito Strains.

    PubMed

    Meepagala, Kumudini M; Estep, Alden S; Becnel, James J

    2016-06-22

    Mosquitoes play a major role as vectors that transmit parasitic and viral diseases worldwide, especially in tropical and subtropical countries. Mosquito borne diseases not only affect humans but they also affect livestock in many parts of the world. They carry diseases that are lethal to dogs and horses. Dog heartworm disease (Dirofilaria immitis) is a parasitic disease spread through mosquitoes. This disease is not limited to dogs, but it can affect other animals and humans as well. Eastern equine encephalitis (EEE) and West Nile virus (WNV) are also mosquito borne diseases that affect the central nervous system of horses and cause severe complications and death. Emergence of resistance among mosquitoes to current pesticides has increased the importance of the search for alternate compounds that are effective and environmentally benign with diverse modes of actions than those that are commercially available. Aedes aegypti mosquitoes are the primary vector for transmission of Zika viral fever, yellow fever, dengue fever, and chikungunya. Mosquito control is currently the best strategy to prevent mosquito borne diseases. There are numerous approaches for control of potentially dangerous mosquito populations. These approaches include the use of adulticides (insecticides), larvicides, and, to a limited extent, the use of repellents. Our previous studies have shown the mosquito repellent activity of chromenes. In the present study, we demonstrate larvicidal and adulticidal activity of chroman and chromene analogues against a permethrin susceptible laboratory strain as well as activity against a permethrin-resistant strain of Aedes aegypti.

  1. Larvicidal and Adulticidal Activity of Chroman and Chromene Analogues against Susceptible and Permethrin-Resistant Mosquito Strains.

    PubMed

    Meepagala, Kumudini M; Estep, Alden S; Becnel, James J

    2016-06-22

    Mosquitoes play a major role as vectors that transmit parasitic and viral diseases worldwide, especially in tropical and subtropical countries. Mosquito borne diseases not only affect humans but they also affect livestock in many parts of the world. They carry diseases that are lethal to dogs and horses. Dog heartworm disease (Dirofilaria immitis) is a parasitic disease spread through mosquitoes. This disease is not limited to dogs, but it can affect other animals and humans as well. Eastern equine encephalitis (EEE) and West Nile virus (WNV) are also mosquito borne diseases that affect the central nervous system of horses and cause severe complications and death. Emergence of resistance among mosquitoes to current pesticides has increased the importance of the search for alternate compounds that are effective and environmentally benign with diverse modes of actions than those that are commercially available. Aedes aegypti mosquitoes are the primary vector for transmission of Zika viral fever, yellow fever, dengue fever, and chikungunya. Mosquito control is currently the best strategy to prevent mosquito borne diseases. There are numerous approaches for control of potentially dangerous mosquito populations. These approaches include the use of adulticides (insecticides), larvicides, and, to a limited extent, the use of repellents. Our previous studies have shown the mosquito repellent activity of chromenes. In the present study, we demonstrate larvicidal and adulticidal activity of chroman and chromene analogues against a permethrin susceptible laboratory strain as well as activity against a permethrin-resistant strain of Aedes aegypti. PMID:27249182

  2. Diphenyl diselenide elicits antidepressant-like activity in rats exposed to monosodium glutamate: A contribution of serotonin uptake and Na(+), K(+)-ATPase activity.

    PubMed

    Quines, Caroline B; Rosa, Suzan G; Velasquez, Daniela; Da Rocha, Juliana T; Neto, José S S; Nogueira, Cristina W

    2016-03-15

    Depression is a disorder with symptoms manifested at the psychological, behavioral and physiological levels. Monosodium glutamate (MSG) is the most widely used additive in the food industry; however, some adverse effects induced by this additive have been demonstrated in experimental animals and humans, including functional and behavioral alterations. The aim of this study was to investigate the possible antidepressant-like effect of diphenyl diselenide (PhSe)2, an organoselenium compound with pharmacological properties already documented, in the depressive-like behavior induced by MSG in rats. Male and female newborn Wistar rats were divided in control and MSG groups, which received, respectively, a daily subcutaneous injection of saline (0.9%) or MSG (4g/kg/day) from the 1st to 5th postnatal day. At 60th day of life, animals received (PhSe)2 (10mg/kg, intragastrically) 25min before spontaneous locomotor and forced swimming tests (FST). The cerebral cortices of rats were removed to determine [(3)H] serotonin (5-HT) uptake and Na(+), K(+)-ATPase activity. A single administration of (PhSe)2 was effective against locomotor hyperactivity caused by MSG in rats. (PhSe)2 treatment protected against the increase in the immobility time and a decrease in the latency for the first episode of immobility in the FST induced by MSG. Furthermore, (PhSe)2 reduced the [(3)H] 5-HT uptake and restored Na(+), K(+)-ATPase activity altered by MSG. In the present study a single administration of (PhSe)2 elicited an antidepressant-like effect and decrease the synaptosomal [(3)H] 5-HT uptake and an increase in the Na(+), K(+)-ATPase activity in MSG-treated rats.

  3. The combination of glutamate receptor antagonist MK-801 with tamoxifen and its active metabolites potentiates their antiproliferative activity in mouse melanoma K1735-M2 cells

    SciTech Connect

    Ribeiro, Mariana P.C.; Nunes-Correia, Isabel; Santos, Armanda E.; Custódio, José B.A.

    2014-02-15

    Recent reports suggest that N-methyl-D-aspartate receptor (NMDAR) blockade by MK-801 decreases tumor growth. Thus, we investigated whether other ionotropic glutamate receptor (iGluR) antagonists were also able to modulate the proliferation of melanoma cells. On the other hand, the antiestrogen tamoxifen (TAM) decreases the proliferation of melanoma cells, and is included in combined therapies for melanoma. As the efficacy of TAM is limited by its metabolism, we investigated the effects of the NMDAR antagonist MK-801 in combination with TAM and its active metabolites, 4-hydroxytamoxifen (OHTAM) and endoxifen (EDX). The NMDAR blockers MK-801 and memantine decreased mouse melanoma K1735-M2 cell proliferation. In contrast, the NMDAR competitive antagonist APV and the AMPA and kainate receptor antagonist NBQX did not affect cell proliferation, suggesting that among the iGluR antagonists only the NMDAR channel blockers inhibit melanoma cell proliferation. The combination of antiestrogens with MK-801 potentiated their individual effects on cell biomass due to diminished cell proliferation, since it decreased the cell number and DNA synthesis without increasing cell death. Importantly, TAM metabolites combined with MK-801 promoted cell cycle arrest in G1. Therefore, the data obtained suggest that the activity of MK-801 and antiestrogens in K1735-M2 cells is greatly enhanced when used in combination. - Highlights: • MK-801 and memantine decrease melanoma cell proliferation. • The combination of MK-801 with antiestrogens inhibits melanoma cell proliferation. • These combinations greatly enhance the effects of the compounds individually. • MK-801 combined with tamoxifen active metabolites induces cell cycle arrest in G1. • The combination of MK-801 and antiestrogens is an innovative strategy for melanoma.

  4. 1,25-Dihydroxyvitamin D3 and its analogues increase catalase at the mRNA, protein and activity level in a canine transitional carcinoma cell line.

    PubMed

    Middleton, R P; Nelson, R; Li, Q; Blanton, A; Labuda, J A; Vitt, J; Inpanbutr, N

    2015-12-01

    Antioxidant enzymes, such as catalase, superoxide dismutases (SOD), MnSOD and Cu/ZnSOD, protect cells by scavenging reactive oxygen species (ROS). Numerous studies have reported the anti-cancer effects of 1,25-dihydroxyvitamin D3 (calcitriol) and its related analogues, seocalcitol and analogue V. In this study, canine bladder transitional cell carcinoma (cbTCC) cells were used to determine effects of calcitriol and its related analogues on antioxidant enzyme gene expression, protein expression and activity. Catalase mRNA was increased in response to calcitriol (10(-7) M), and seocalcitol (10(-7) and 10(-9) M). MnSOD mRNA was decreased in response to calcitriol at 10(-7) M. Catalase was significantly increased in response to calcitriol (10(-7) and 10(-9) M), and seocalcitol (10(-9) M). Catalase enzymatic activity increased in response to calcitriol, seocalcitol and analogue V (10(-9) M). In addition, global gene expression analysis identified the involvement of mitogen-activated protein kinase (MAPK) signalling in cbTCC's response to calcitriol and seocalcitol treatment.

  5. Development of a comprehensive spectral library of sildenafil and related active analogues using LC-QTOF-MS and its application for screening counterfeit pharmaceuticals.

    PubMed

    Lee, Sooyeun; Ji, Dajeong; Park, Meejung; Chung, Kyu Hyuck

    2015-12-01

    The abuse or misuse of forged erectile-dysfunction drugs, containing phosphodiesterase type 5 inhibitors (e.g. sildenafil), is a serious issue globally. Therefore, the detection of sildenafil and related active analogues in counterfeit pharmaceuticals or the differentiation between counterfeit and authentic drugs has been performed with a variety of analytical techniques. Recently, a liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS)-based in-house library, consisting of accurate mass ion fragmentation information and retention times, was effectively applied to screen a large number of compounds in field of forensic toxicology. However, a comprehensive LC-QTOF-MS spectral library of sildenafil and related active analogues has not yet been reported. In the present study, a spectral library of 40 compounds of sildenafil and related analogues was developed with accurate mass spectra and retention times using LC-QTOF-MS, and applied to screen nine marketed counterfeit products. The in-house library successfully identified sildenafil, dimethylsildenafil, hydroxyhomosildenafil, demethylhongdenafil, pseudovardenafil and vardenafil in the samples. Our LC-QTOF-MS-based spectral library search is considered a powerful approach for identifying sildenafil and related active analogues in counterfeit pharmaceuticals.

  6. Synthesis and photodynamic activity of unsymmetrical A3B tetraarylporphyrins functionalized with l-glutamate and their Zn(II) and Cu(II) metal complex derivatives.

    PubMed

    Arredondo-Espinoza, Eder U; López-Cortina, Susana T; Ramírez-Cabrera, Mónica A; Balderas-Rentería, Isaías

    2016-08-01

    Four novel unsymmetrical A3B porphyrins 1, 2, 3 and 4 were synthesized following Lindsey procedure. Porphyrins 3 and 4 include one and three l-glutamate groups, respectively, and all porphyrins were metallated with Zn(II) (1a-4a) or Cu(II) (1b-4b). Porphyrins and metalloporphyrins presented values of singlet oxygen quantum yields (ΦD) ranging from 0.21 to 0.67. The tetraaryl derivatives in this study showed phototoxicity in SiHa cells with IC50 values ranging from <0.01 to 6.56±0.11μM, the metalloporphyrin 4a showed the lowest IC50 value. Comparing the phototoxic activity between all porphyrins, functionalization of porphyrins with glutamate increased 100 times phototoxic activity (1 (IC50 4.81±0.34μM) vs. 3 (IC50 0.04±0.02μM) and 2 (IC50 5.19±0.42μM) vs. 4 (IC50 0.05±0.01μM)). This increased activity could be attributed to reduced hydrophobicity and increased ΦΔ, given by functionalization with l-glutamate. Metalloporphyrins 3a (IC50 0.04±0.01μM) and 4a (IC50<0.01μM) presented the best values ​​of phototoxic activity. Therefore, functionalization and zinc metalation increased the phototoxic activity. SiHa cells treated with porphyrins 3, 4, 3a and 4a at a final concentration of 10μM, showed increased activity of caspase-3 enzyme compared to the negative control; indicating the induction of apoptosis. Differential gene expression pattern in SiHa cells was determined; treatments with metalloporphyrins 4a and 4b were performed, respectively, comparing the expression with untreated control. Treatments in both cases showed similar gene expression pattern in upregulated genes, since they share about 25 biological pathways and a large number of genes. According to the new photophysical properties related to the structural improvement and phototoxic activity, these molecules may have the potential application as photosensitizers in the photodynamic therapy.

  7. Developmental changes in choline acetyltransferase and glutamate decarboxylase activity in various regions of the brain of the male, female, and neonatally androgenized female rat.

    PubMed

    Brown, R; Brooksbank, B W

    1979-04-01

    In attempt to discern effects of sex hormones on the development of neurotransmitter systems in the rat brain, choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) have been measured at postnatal days 8, 12, 25, and 60 in five regions (amygdala, anterior hypothalamus, hippocampus, olfactory bulbs, and cerebral cortex) of the brains of normal male, normal female, and neonatally androgen-treated female rats. Essentially no association between sex or of neonatal "androgenization" on either enzymol were found. The data, however, provide new information on the relative rates of development of ChAT and GAD in five regions of the rat brain which supplement the limited information already available in the literature. ChAT activity was highest in amygdala and hypothalamus, but developed most rapidly in hippocampus and cerebral cortex. The relative activities and patterns of development of GAD activity were similar to those of ChAT.

  8. Upregulation of transmitter release probability improves a conversion of synaptic analogue signals into neuronal digital spikes

    PubMed Central

    2012-01-01

    Action potentials at the neurons and graded signals at the synapses are primary codes in the brain. In terms of their functional interaction, the studies were focused on the influence of presynaptic spike patterns on synaptic activities. How the synapse dynamics quantitatively regulates the encoding of postsynaptic digital spikes remains unclear. We investigated this question at unitary glutamatergic synapses on cortical GABAergic neurons, especially the quantitative influences of release probability on synapse dynamics and neuronal encoding. Glutamate release probability and synaptic strength are proportionally upregulated by presynaptic sequential spikes. The upregulation of release probability and the efficiency of probability-driven synaptic facilitation are strengthened by elevating presynaptic spike frequency and Ca2+. The upregulation of release probability improves spike capacity and timing precision at postsynaptic neuron. These results suggest that the upregulation of presynaptic glutamate release facilitates a conversion of synaptic analogue signals into digital spikes in postsynaptic neurons, i.e., a functional compatibility between presynaptic and postsynaptic partners. PMID:22852823

  9. B-Ring-Aryl Substituted Luotonin A Analogues with a New Binding Mode to the Topoisomerase 1-DNA Complex Show Enhanced Cytotoxic Activity

    PubMed Central

    González-Ruiz, Víctor; Pascua, Irene; Fernández-Marcelo, Tamara; Ribelles, Pascual; Bianchini, Giulia; Sridharan, Vellaisamy; Iniesta, Pilar; Ramos, M. Teresa; Olives, Ana I.; Martín, M. Antonia; Menéndez, J. Carlos

    2014-01-01

    Topoisomerase 1 inhibition is an important strategy in targeted cancer chemotherapy. The drugs currently in use acting on this enzyme belong to the family of the camptothecins, and suffer severe limitations because of their low stability, which is associated with the hydrolysis of the δ-lactone moiety in their E ring. Luotonin A is a natural camptothecin analogue that lacks this functional group and therefore shows a much-improved stability, but at the cost of a lower activity. Therefore, the development of luotonin A analogues with an increased potency is important for progress in this area. In the present paper, a small library of luotonin A analogues modified at their A and B rings was generated by cerium(IV) ammonium nitrate-catalyzed Friedländer reactions. All analogues showed an activity similar or higher than the natural luotonin A in terms of topoisomerase 1 inhibition and some compounds had an activity comparable to that of camptothecin. Furthermore, most compounds showed a better activity than luotonin A in cell cytotoxicity assays. In order to rationalize these results, the first docking studies of luotonin-topoisomerase 1-DNA ternary complexes were undertaken. Most compounds bound in a manner similar to luotonin A and to standard topoisomerase poisons such as topotecan but, interestingly, the two most promising analogues, bearing a 3,5-dimethylphenyl substituent at ring B, docked in a different orientation. This binding mode allows the hydrophobic moiety to be shielded from the aqueous environment by being buried between the deoxyribose belonging to the G(+1) guanine and Arg364 in the scissile strand and the surface of the protein and a hydrogen bond between the D-ring carbonyl and the basic amino acid. The discovery of this new binding mode and its associated higher inhibitory potency is a significant advance in the design of new topoisomerase 1 inhibitors. PMID:24830682

  10. Ca2+ Activation kinetics of the two aspartate-glutamate mitochondrial carriers, aralar and citrin: role in the heart malate-aspartate NADH shuttle.

    PubMed

    Contreras, Laura; Gomez-Puertas, Paulino; Iijima, Mikio; Kobayashi, Keiko; Saheki, Takeyori; Satrústegui, Jorgina

    2007-03-01

    Ca(2+) regulation of the Ca(2+) binding mitochondrial carriers for aspartate/glutamate (AGCs) is provided by their N-terminal extensions, which face the intermembrane space. The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle. We report that their N-terminal extensions contain up to four pairs of EF-hand motifs plus a single vestigial EF-hand, and have no known homolog. Aralar and citrin contain one fully canonical EF-hand pair and aralar two additional half-pairs, in which a single EF-hand is predicted to bind Ca(2+). Shuttle activity in brain or skeletal muscle mitochondria, which contain aralar as the major AGC, is activated by Ca(2+) with S(0.5) values of 280-350 nm; higher than those obtained in liver mitochondria (100-150 nm) that contain citrin as the major AGC. We have used aralar- and citrin-deficient mice to study the role of the two isoforms in heart, which expresses both AGCs. The S(0.5) for Ca(2+) activation of the shuttle in heart mitochondria is about 300 nm, and it remains essentially unchanged in citrin-deficient mice, although it undergoes a drastic reduction to about 100 nm in aralar-deficient mice. Therefore, aralar and citrin, when expressed as single isoforms in heart, confer differences in Ca(2+) activation of shuttle activity, probably associated with their structural differences. In addition, the results reveal that the two AGCs fully account for shuttle activity in mouse heart mitochondria and that no other glutamate transporter can replace the AGCs in this pathway.

  11. Synthesis and Anti-Influenza Activity of Pyridine, Pyridazine, and Pyrimidine C-Nucleosides as Favipiravir (T-705) Analogues.

    PubMed

    Wang, Guangyi; Wan, Jinqiao; Hu, Yujian; Wu, Xiangyang; Prhavc, Marija; Dyatkina, Natalia; Rajwanshi, Vivek K; Smith, David B; Jekle, Andreas; Kinkade, April; Symons, Julian A; Jin, Zhinan; Deval, Jerome; Zhang, Qingling; Tam, Yuen; Chanda, Sushmita; Blatt, Lawrence; Beigelman, Leonid

    2016-05-26

    Influenza viruses are responsible for seasonal epidemics and occasional pandemics which cause significant morbidity and mortality. Despite available vaccines, only partial protection is achieved. Currently, there are two classes of widely approved anti-influenza drugs: M2 ion channel blockers and neuraminidase inhibitors. However, the worldwide spread of drug-resistant influenza strains poses an urgent need for novel antiviral drugs, particularly with a different mechanism of action. Favipiravir (T-705), a broad-spectrum antiviral agent, has shown potent anti-influenza activity in cell-based assays, and its riboside (2) triphosphate inhibited influenza polymerase. In one of our approaches to treat influenza infection, we designed, prepared, and tested a series of C-nucleoside analogues, which have an analogy to 2 and were expected to act by a similar antiviral mechanism as favipiravir. Compound 3c of this report exhibited potent inhibition of influenza virus replication in MDCK cells, and its triphosphate was a substrate of and demonstrated inhibitory activity against influenza A polymerase. Metabolites of 3c are also presented.

  12. Late Quaternary high resolution sequence stratigraphy of an active rift, the Sperchios Basin, Greece: An analogue for subtle stratigraphic plays

    SciTech Connect

    Eliet, P.P.; Gawthorpe, R.L.

    1996-12-31

    The Sperchios Basin is an active asymmetric graben, bounded to the south by a major border fault system with major fault segments typically 20-30 km long. The basin is dominated by a major axial fluvio-deltaic system which enters the partially enclosed Maliakos Gulf to the east. Lateral sourced depositional systems within the basin comprise hanging-wall and footwall-derived alluvial fans and a narrow coastal plain along the footwall scarp bordering the Maliakos Gulf. High resolution seismic data from the Maliakos Gulf reveals three late Quaternary progradational parasequences sourced from axial and lateral depositional systems, with a regional late-Pleistocene transgressive surface dated at circa. 10 ka BP within the Maliakos Gulf. Differential subsidence of the late Pleistocene transgressive surface indicates marked variation in subsidence from 2.4 m ka{sup -1} at fault segment centers to 0.8 m ka{sup -1} at segment boundaries. The geometry and internal variability of each parasequence is controlled by the interplay of the local accommodation development and fluctuations in sediment supply and climatic conditions. The Sperchios Rift provides a modem analogue for subtle stratigraphic plays within ancient extensional basins. The study of controls on sediment source and transport patterns within active rifts has refined our appreciation of the controls on potential reservoir distribution and geometries.

  13. Late Quaternary high resolution sequence stratigraphy of an active rift, the Sperchios Basin, Greece: An analogue for subtle stratigraphic plays

    SciTech Connect

    Eliet, P.P. ); Gawthorpe, R.L. )

    1996-01-01

    The Sperchios Basin is an active asymmetric graben, bounded to the south by a major border fault system with major fault segments typically 20-30 km long. The basin is dominated by a major axial fluvio-deltaic system which enters the partially enclosed Maliakos Gulf to the east. Lateral sourced depositional systems within the basin comprise hanging-wall and footwall-derived alluvial fans and a narrow coastal plain along the footwall scarp bordering the Maliakos Gulf. High resolution seismic data from the Maliakos Gulf reveals three late Quaternary progradational parasequences sourced from axial and lateral depositional systems, with a regional late-Pleistocene transgressive surface dated at circa. 10 ka BP within the Maliakos Gulf. Differential subsidence of the late Pleistocene transgressive surface indicates marked variation in subsidence from 2.4 m ka[sup -1] at fault segment centers to 0.8 m ka[sup -1] at segment boundaries. The geometry and internal variability of each parasequence is controlled by the interplay of the local accommodation development and fluctuations in sediment supply and climatic conditions. The Sperchios Rift provides a modem analogue for subtle stratigraphic plays within ancient extensional basins. The study of controls on sediment source and transport patterns within active rifts has refined our appreciation of the controls on potential reservoir distribution and geometries.

  14. Synthesis and Anti-Influenza Activity of Pyridine, Pyridazine, and Pyrimidine C-Nucleosides as Favipiravir (T-705) Analogues.

    PubMed

    Wang, Guangyi; Wan, Jinqiao; Hu, Yujian; Wu, Xiangyang; Prhavc, Marija; Dyatkina, Natalia; Rajwanshi, Vivek K; Smith, David B; Jekle, Andreas; Kinkade, April; Symons, Julian A; Jin, Zhinan; Deval, Jerome; Zhang, Qingling; Tam, Yuen; Chanda, Sushmita; Blatt, Lawrence; Beigelman, Leonid

    2016-05-26

    Influenza viruses are responsible for seasonal epidemics and occasional pandemics which cause significant morbidity and mortality. Despite available vaccines, only partial protection is achieved. Currently, there are two classes of widely approved anti-influenza drugs: M2 ion channel blockers and neuraminidase inhibitors. However, the worldwide spread of drug-resistant influenza strains poses an urgent need for novel antiviral drugs, particularly with a different mechanism of action. Favipiravir (T-705), a broad-spectrum antiviral agent, has shown potent anti-influenza activity in cell-based assays, and its riboside (2) triphosphate inhibited influenza polymerase. In one of our approaches to treat influenza infection, we designed, prepared, and tested a series of C-nucleoside analogues, which have an analogy to 2 and were expected to act by a similar antiviral mechanism as favipiravir. Compound 3c of this report exhibited potent inhibition of influenza virus replication in MDCK cells, and its triphosphate was a substrate of and demonstrated inhibitory activity against influenza A polymerase. Metabolites of 3c are also presented. PMID:27120583

  15. Synthesis and biological activity of pyrazole analogues of the staurosporine aglycon K252c.

    PubMed

    Esvan, Yannick J; Giraud, Francis; Pereira, Elisabeth; Suchaud, Virginie; Nauton, Lionel; Théry, Vincent; Dezhenkova, Lyubov G; Kaluzhny, Dmitry N; Mazov, Vsevolod N; Shtil, Alexander A; Anizon, Fabrice; Moreau, Pascale

    2016-07-15

    A derivative of the staurosporine aglycon (K252c), in which the lactam ring was replaced by a pyrazole moiety, was synthesized. The resulting indolopyrazolocarbazole (3) inhibited Pim isoforms 1-3 whereas it did not impair the activity of two known targets of K252c, protein kinase C isoforms α and γ. Compound 3 exhibited moderate cytotoxic activity toward human leukemia and colon carcinoma cell lines (K562 and HCT116), strongly suggesting that this new scaffold deserves further investigations for treatment of malignancies associated with Pim activity. PMID:27255178

  16. Investigating the activity of quinine analogues vs. chloroquine resistant Plasmodium falciparum

    PubMed Central

    Dinio, Theresa; Gorka, Alexander P.; McGinniss, Andrew; Roepe, Paul D.; Morgan, Jeremy B.

    2012-01-01

    Plasmodium falciparum, the deadliest malarial parasite species, has developed resistance against nearly all man-made antimalarial drugs within the past century. However, quinine (QN), the first antimalarial drug, remains efficacious worldwide. Some chloroquine resistant (CQR) P. falciparum strains or isolates show mild cross resistance to QN, but many do not. Further optimization of QN may provide well-tolerated therapy with improved activity vs. CQR malaria. Thus, using the Heck reaction, we have pursued a structure-activity relationship study, including vinyl group modifications of QN. Certain derivatives show good antiplasmodial activity in QN-resistant and QN-sensitive strains, with lower IC50 values relative to QN. PMID:22512909

  17. Antimicrobial Activity of Novel C2-Substituted 1,4-Dihydropyridine Analogues

    PubMed Central

    Olejníková, Petra; Švorc, L’ubomír; Olšovská, Denisa; Panáková, Anna; Vihonská, Zuzana; Kovaryová, Katarína; Marchalín, Štefan

    2014-01-01

    The antimicrobial activity of 3-methyl-5-isopropyl (or ethyl) 6-methyl-4-nitrophenyl-1,4-dihydropyridine-3,5-dicarboxylate derivatives was evaluated. Prokaryotes (bacteria) appeared to be more sensitive to their antimicrobial activity than were eukaryotes (filamentous fungi). The best antibacterial activity was shown by derivative 33, which was able to inhibit the growth of Mycobacterium smegmatis (MIC33 = 9 μg.ml−1), Staphylococcus aureus (MIC33 = 25 μg.ml−1), and Escherichia coli (MIC33 = 100 μg.ml−1). In addition, derivative 4 demonstrated its antibacterial power on the acid-fast bacterial species M. smegmatis and on Gram-positive S. aureus. Focusing on the structure-activity relationship, it appears that the increase in the substituent bulk at the C2 position improved the antibacterial activity of the set of compounds studied. Derivatives 33 and 4, carrying 2-cyano-3-oxo-3-phenylprop-1-en-1-yl and allyliminomethyl groups, respectively, showed significantly higher inhibition activities on all tested microorganisms in comparison with the rest of the derivatives. This enhancement was also in good correlation with different log P values (lipophilicity parameter). PMID:24959401

  18. Antimicrobial Peptide from the Wild Bee Hylaeus signatus Venom and Its Analogues: Structure-Activity Study and Synergistic Effect with Antibiotics.

    PubMed

    Nešuta, Ondřej; Hexnerová, Rozálie; Buděšínský, Miloš; Slaninová, Jiřina; Bednárová, Lucie; Hadravová, Romana; Straka, Jakub; Veverka, Václav; Čeřovský, Václav

    2016-04-22

    Venoms of hymenopteran insects have attracted considerable interest as a source of cationic antimicrobial peptides (AMPs). In the venom of the solitary bee Hylaeus signatus (Hymenoptera: Colletidae), we identified a new hexadecapeptide of sequence Gly-Ile-Met-Ser-Ser-Leu-Met-Lys-Lys-Leu-Ala-Ala-His-Ile-Ala-Lys-NH2. Named HYL, it belongs to the category of α-helical amphipathic AMPs. HYL exhibited weak antimicrobial activity against several strains of pathogenic bacteria and moderate activity against Candida albicans, but its hemolytic activity against human red blood cells was low. We prepared a set of HYL analogues to evaluate the effects of structural modifications on its biological activity and to increase its potency against pathogenic bacteria. This produced several analogues exhibiting significantly greater activity compared to HYL against strains of both Staphylococcus aureus and Pseudomonas aeruginosa even as their hemolytic activity remained low. Studying synergism of HYL peptides and conventional antibiotics showed the peptides act synergistically and preferentially in combination with rifampicin. Fluorescent dye propidium iodide uptake showed the tested peptides were able to facilitate entrance of antibiotics into the cytoplasm by permeabilization of the outer and inner bacterial cell membrane of P. aeruginosa. Transmission electron microscopy revealed that treatment of P. aeruginosa with one of the HYL analogues caused total disintegration of bacterial cells. NMR spectroscopy was used to elucidate the structure-activity relationship for the effect of amino acid residue substitution in HYL. PMID:26998557

  19. Glutamate and Neurodegenerative Disease

    NASA Astrophysics Data System (ADS)

    Schaeffer, Eric; Duplantier, Allen

    As the main excitatory neurotransmitter in the mammalian central nervous system, glutamate is critically involved in most aspects of CNS function. Given this critical role, it is not surprising that glutamatergic dysfunction is associated with many CNS disorders. In this chapter, we review the literature that links aberrant glutamate neurotransmission with CNS pathology, with a focus on neurodegenerative diseases. The biology and pharmacology of the various glutamate receptor families are discussed, along with data which links these receptors with neurodegenerative conditions. In addition, we review progress that has been made in developing small molecule modulators of glutamate receptors and transporters, and describe how these compounds have helped us understand the complex pharmacology of glutamate in normal CNS function, as well as their potential for the treatment of neurodegenerative diseases.

  20. Hydrocarbon stapled B chain analogues of relaxin-3 retain biological activity.

    PubMed

    Jayakody, Tharindunee; Marwari, Subhi; Lakshminarayanan, Rajamani; Tan, Francis Chee Kuan; Johannes, Charles William; Dymock, Brian William; Poulsen, Anders; Herr, Deron Raymond; Dawe, Gavin Stewart

    2016-10-01

    Relaxin-3 or insulin-like peptide 7 (INSL7) is the most recently discovered relaxin/insulin-like family peptide. Mature relaxin-3 consists of an A chain and a B chain held by disulphide bonds. According to structure activity relationship studies, the relaxin-3 B chain is more important in binding and activating the receptor. RXFP3 (also known as Relaxin-3 receptor 1, GPCR 135, somatostatin- and angiotensin- like peptide receptor or SALPR) was identified as the cognate receptor for relaxin-3 by expression profiles and binding studies. Recent studies imply roles of this system in mediating stress and anxiety, feeding, metabolism and cognition. Stapling of peptides is a technique used to develop peptide drugs for otherwise undruggable targets. The main advantages of stapling include, increased activity due to reduced proteolysis, increased affinity to receptors and increased cell permeability. Stable agonists and antagonists of RXFP3 are crucial for understanding the physiological significance of this system. So far, agonists and antagonists of RXFP3 are peptides. In this study, for the first time, we have introduced stapling of the relaxin-3 B chain at 14th and 18th positions (14s18) and 18th and 22nd position (18s22). These stapled peptides showed greater helicity than the unstapled relaxin-3 B chain in circular dichroism analysis. Both stapled peptides bound RXFP3 and activated RXFP3 as observed in an inhibition of forskolin-induced cAMP assay and a ERK1/2 activation assay, although with different potencies. Therefore, we conclude that stapling of the relaxin3 B chain does not compromise its ability to activate RXFP3 and is a promising method for developing stable peptide agonists and antagonists of RXFP3 to aid relaxin-3/RXFP3 research. PMID:27498038

  1. Synthesis and nucleophilic reactivity of a series of glutathione analogues, modified at the gamma-glutamyl moiety.

    PubMed Central

    Adang, A E; Duindam, A J; Brussee, J; Mulder, G J; van der Gen, A

    1988-01-01

    A series of GSH analogues with modifications at the gamma-glutamyl moiety was synthesized and purified by following peptide chemistry methodology. Benzyl, benzyloxycarbonyl and t-butyloxycarbonyl protective groups were used to protect individual amino acid functional groups. The formation of peptide bonds was accomplished through coupling of free amino groups with active esters, generated by reaction of the carboxylate functions with dicyclohexylcarbodi-imide and 1-hydroxybenzotriazole. The protecting groups in the tripeptides were removed in a single step by using Na in liquid NH3. Precautions were taken in order to prevent oxidation of the thiol function in the cysteine residue. Thus GSH analogues containing both L- and D-glutamic acid and L- and D-aspartic acid, coupled to cysteinylglycine through both the alpha- and the omega-carboxylate group, were synthesized. Also, decarboxy-GSH and deamino-GSH, lacking one functional group in the glutamate moiety, were prepared. The spontaneous non-enzyme-catalysed nucleophilic reaction of these GSH analogues with the electrophilic model substrate 1-chloro-2,4-dinitrobenzene showed appreciable rate differences, indicating the importance of intramolecular interactions in determining the nucleophilic reactivity of the thiol function in the cysteine residue. In particular, the free amino group in the gamma-L-glutamic acid residue appears to play a crucial role in activating the thiol group in GSH. In an adjacent paper [Adang, Brussee, Meyer, Coles, Ketterer, van der Gen & Mulder (1988) Biochem. J. 255, 721-724] these results are compared with those obtained in a study on the ability of these GSH analogues to act as a co-substrate in the glutathione S-transferase-catalysed conjugation reaction with 1-chloro-2,4-dinitrobenzene. PMID:2904808

  2. Plasma aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH) and gamma-glutamyl transpeptidase (GGT) activities in water buffaloes with experimental subclinical fasciolosis.

    PubMed

    Yang, Q; Mao, W H; Ferre, I; Bayón, J E; Mao, X Z; González-Gallego, J

    1998-07-31

    The effect of chronic Fasciola hepatica infection on the activity of plasma aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH) and gamma-glutamyl transpeptidase (GGT) was investigated in water buffaloes dosed daily with 60 F. hepatica metacercariae over 20 days. Experimental fluke infection caused no clinical signs but provoked an increase in plasma level of IgG directed against F. hepatica from 4 weeks after infection. There was a significant increase in plasma AST from 6 weeks post-infection. Maximal values were reached at 14 weeks and remained significantly elevated by 23 weeks. Plasma GLDH was significantly elevated from 6 to 21 weeks post-infection. Significant increases in plasma GGT occurred from 8 to 26 weeks post-infection, reaching maximal values at 15 weeks. This study shows that plasma enzyme activities may be useful in studies of fluke-induced liver damage in water buffaloes.

  3. A novel GSK-3β inhibitor YQ138 prevents neuronal injury induced by glutamate and brain ischemia through activation of the Nrf2 signaling pathway

    PubMed Central

    Pang, Tao; Wang, Yun-jie; Gao, Yuan-xue; Xu, Yuan; Li, Qiu; Zhou, Yu-bo; Xu, Lei; Huang, Zhang-jian; Liao, Hong; Zhang, Lu-yong; Gao, Jian-rong; Ye, Qing; Li, Jia

    2016-01-01

    Aim: To discover neuroprotective compounds and to characterize the discovered active compound YQ138 as a novel GSK-3β inhibitor. Methods: Primary rat cerebellar granule cells (CGCs) were treated with glutamate, and cell viability was analyzed with MTT assay, which was used as in vitro model for screening neuroprotective compounds. Active compound was further tested in OGD- or serum deprivation-induced neuronal injury models. The expression levels of GSK-3β downstream proteins (Nrf2, HO-1, NQO1, Tau and β-catenin) were detected with Western blotting. For evaluating the neuroprotective effects in vivo, adult male rats were subjected to transient middle cerebral artery occlusion (tMCAO), then treated with YQ138 (10 mg/kg, iv) at 2, 4 and 6 h after ischemia onset. Results: From a compound library consisting of about 2000 potential kinase inhibitors, YQ138 was found to exert neuroprotective effects: pretreatment with YQ138 (0.1–40 μmol/L) dose-dependently inhibited glutamate-induced neuronal death. Furthermore, pretreatment with YQ138 (10 μmol/L) significantly inhibited OGD- or serum deprivation-induced neuronal death. Among a panel of seven kinases tested, YQ138 selectively inhibited the activity of GSK-3β (IC50=0.52 nmol/L). Furthermore, YQ138 dose-dependently increased the expression of β-catenin, and decreased the phosphorylation of Tau in CGCs. Moreover, YQ138 significantly increased the expression of GSK-3β downstream antioxidative proteins Nrf2, HO-1, NQO1, GSH and SOD in CGCs. In rats with tMCAO, administration of YQ138 significantly decreased infarct volume, improved the neurological deficit, and increased the expression of Nrf2 and HO-1 and the activities of SOD and GSH in the cerebral cortex. Conclusion: A novel GSK-3β inhibitor YQ138 effectively suppresses brain ischemic injury in vitro and in vivo. PMID:27108601

  4. Preconcentration and Speciation of Trace Elements and Trace-Element Analogues of Radionuclides by Neutron Activation Analysis

    SciTech Connect

    Chatt, A.

    1999-11-14

    We have developed a number of preconcentration neutron activation analysis (PNAA) methods in our laboratory for the determination of trace elements in a variety of complex sample matrices. We developed a number of cocrystallization and coprecipitation methods for the determination of trace elements in water samples. We developed several methods for the determination of I in foods and diets. We have developed a number of PNAA methods in our laboratory We determined As and Sb in geological materials and natural waters by coprecipitation with Se and Au in silicate rocks and ores by coprecipitation with Te followed by NAA. We developed an indirect NAA method for the determination of B in leachates of borosilicate glass. We have been interested in studying the speciation of Am, Tc, and Np in simulated vitrified groundwater leachates of high-level wastes under oxid and anoxic conditions using a number of techniques. We then used PNAA methods to study speciation of trace-element analogues of radionuclides. We have been able to apply biochemical techniques and NAA for the separation, preconcentration, and characterization of metalloprotein and protein-bound trace-element species in subcellular fractions of bovine kidneys. Lately, we have concentrated our efforts to develop chemical and biochemical methods in conjunction with NAA, NMR, and MS for the separation and identification of extractable organohalogens (EOX) in tissues of beluga whales, cod, and northern pink shrimp

  5. Synthesis and anti-Plasmodium activity of benzimidazole analogues structurally related to astemizole.

    PubMed

    Roman, Gheorghe; Crandall, Ian E; Szarek, Walter A

    2013-11-01

    A series of compounds structurally related to astemizole were designed and synthesized with the goal of determining their anti-Plasmodium activity. Several modifications of the astemizole structure, namely the removal of the 4-fluorobenzyl and/or 4-methoxyphenethyl moieties, substitution of the benzene ring of the benzimidazole scaffold, replacement of the fluorine atom in the 4-fluorobenzyl group, and variation of the 4-aminopiperidine moiety, were explored. In vitro evaluation of the anti-Plasmodium activity of these compounds using the ItG strain showed that astemizole and some of its structurally similar derivatives have IC50 values in the nanomolar range and exhibit toxicity towards the parasite over Chinese ovarian hamster (CHO) cells with a selectivity as high as 200. The presence of a secondary cyclic amine at position 2 and substitution with chlorine at positions 4 and 5 in the benzimidazole moiety are two modifications that resulted in potent and selective antimalarials based on astemizole. PMID:24022991

  6. Two Analogues of Fenarimol Show Curative Activity in an Experimental Model of Chagas Disease

    PubMed Central

    2013-01-01

    Chagas disease, caused by the protozoan parasite Trypanosoma cruzi (T. cruzi), is an increasing threat to global health. Available medicines were introduced over 40 years ago, have undesirable side effects, and give equivocal results of cure in the chronic stage of the disease. We report the development of two compounds, 6 and (S)-7, with PCR-confirmed curative activity in a mouse model of established T. cruzi infection after once daily oral dosing for 20 days at 20 mg/kg 6 and 10 mg/kg (S)-7. Compounds 6 and (S)-7 have potent in vitro activity, are noncytotoxic, show no adverse effects in vivo following repeat dosing, are prepared by a short synthetic route, and have druglike properties suitable for preclinical development. PMID:24304150

  7. A Functionalized Sphingolipid Analogue for Studying Redistribution during Activation in Living T Cells.

    PubMed

    Collenburg, Lena; Walter, Tim; Burgert, Anne; Müller, Nora; Seibel, Jürgen; Japtok, Lukasz; Kleuser, Burkhard; Sauer, Markus; Schneider-Schaulies, Sibylle

    2016-05-01

    Sphingolipids are major components of the plasma membrane. In particular, ceramide serves as an essential building hub for complex sphingolipids, but also as an organizer of membrane domains segregating receptors and signalosomes. Sphingomyelin breakdown as a result of sphingomyelinase activation after ligation of a variety of receptors is the predominant source of ceramides released at the plasma membrane. This especially applies to T lymphocytes where formation of ceramide-enriched membrane microdomains modulates TCR signaling. Because ceramide release and redistribution occur very rapidly in response to receptor ligation, novel tools to further study these processes in living T cells are urgently needed. To meet this demand, we synthesized nontoxic, azido-functionalized ceramides allowing for bio-orthogonal click-reactions to fluorescently label incorporated ceramides, and thus investigate formation of ceramide-enriched domains. Azido-functionalized C6-ceramides were incorporated into and localized within plasma membrane microdomains and proximal vesicles in T cells. They segregated into clusters after TCR, and especially CD28 ligation, indicating efficient sorting into plasma membrane domains associated with T cell activation; this was abolished upon sphingomyelinase inhibition. Importantly, T cell activation was not abrogated upon incorporation of the compound, which was efficiently excluded from the immune synapse center as has previously been seen in Ab-based studies using fixed cells. Therefore, the functionalized ceramides are novel, highly potent tools to study the subcellular redistribution of ceramides in the course of T cell activation. Moreover, they will certainly also be generally applicable to studies addressing rapid stimulation-mediated ceramide release in living cells. PMID:27036914

  8. Distribution of active faulting along orogenic wedges: Minimum-work models and natural analogue

    NASA Astrophysics Data System (ADS)

    Yagupsky, Daniel L.; Brooks, Benjamin A.; Whipple, Kelin X.; Duncan, Christopher C.; Bevis, Michael

    2014-09-01

    Numerical 2-D models based on the principle of minimum work were used to examine the space-time distribution of active faulting during the evolution of orogenic wedges. A series of models focused on thin-skinned thrusting illustrates the effects of arid conditions (no erosion), unsteady state conditions (accretionary influx greater than erosional efflux) and steady state conditions (accretionary influx balances erosional efflux), on the distribution of fault activity. For arid settings, a general forward accretion sequence prevails, although a significant amount of internal deformation is registered: the resulting fault pattern is a rather uniform spread along the profile. Under fixed erosional efficiency settings, the frontal advance of the wedge-front is inhibited, reaching a steady state after a given forward propagation. Then, the applied shortening is consumed by surface ruptures over a narrow frontal zone. Under a temporal increase in erosional efficiency (i.e., transient non-steady state mass balance conditions), a narrowing of the synthetic wedge results; a rather diffuse fault activity distribution is observed during the deformation front retreat. Once steady balanced conditions are reached, a single long-lived deformation front prevails. Fault activity distribution produced during the deformation front retreat of the latter scenario, compares well with the structural evolution and hinterlandward deformation migration identified in southern Bolivian Subandes (SSA) from late Miocene to present. This analogy supports the notion that the SSA is not in steady state, but is rather responding to an erosional efficiency increase since late Miocene. The results shed light on the impact of different mass balance conditions on the vastly different kinematics found in mountain ranges, suggesting that those affected by growing erosion under a transient unbalanced mass flux condition tend to distribute deformation along both frontal and internal faults, while others

  9. Oxaliplatin Analogues with Carboxy Derivatives of Boldine with Enhanced Antioxidant Activity

    PubMed Central

    Mellado, Marco; Jara, Carlos; Astudillo, David; Villena, Joan; Reveco, Patricio G.; Thomet, Franz A.

    2015-01-01

    A new oxaliplatin analog [Pt(dach)(L5)] (1) was synthesized and characterized as a continuation of a study of the previously reported [Pt(dach)(L6)] (2), where dach = (1R,2R)-diaminocyclohexane, L5 = 3-carboxyboldine, and L6 = 3-carboxypredicentrine. Compounds 1 and 2 exhibited a substantially enhanced antioxidant activity compared to oxaliplatin (130 and 30 times for 1 and 13 and 4 times for 2 using the DPPH and FRAP assays, resp.). In addition, 1 and 2 exhibited cytotoxic activity in the same range as oxaliplatin toward the two human tumor cell lines (MCF-7 and HT-29) studied and two to four times lower activity in the human colon nontumor cell line (CCD-841). Preadministration of L5 or L6 to the colon tumor (HT-29) and the colon nontumor (CCD-841) cell lines prior to oxaliplatin addition increased the viability of the nontumor cell line to a greater extent than that of the tumor cell line. PMID:25814916

  10. Oxaliplatin analogues with carboxy derivatives of boldine with enhanced antioxidant activity.

    PubMed

    Mellado, Marco; Jara, Carlos; Astudillo, David; Villena, Joan; Reveco, Patricio G; Thomet, Franz A

    2015-01-01

    A new oxaliplatin analog [Pt(dach)(L5)] (1) was synthesized and characterized as a continuation of a study of the previously reported [Pt(dach)(L6)] (2), where dach = (1R,2R)-diaminocyclohexane, L5 = 3-carboxyboldine, and L6 = 3-carboxypredicentrine. Compounds 1 and 2 exhibited a substantially enhanced antioxidant activity compared to oxaliplatin (130 and 30 times for 1 and 13 and 4 times for 2 using the DPPH and FRAP assays, resp.). In addition, 1 and 2 exhibited cytotoxic activity in the same range as oxaliplatin toward the two human tumor cell lines (MCF-7 and HT-29) studied and two to four times lower activity in the human colon nontumor cell line (CCD-841). Preadministration of L5 or L6 to the colon tumor (HT-29) and the colon nontumor (CCD-841) cell lines prior to oxaliplatin addition increased the viability of the nontumor cell line to a greater extent than that of the tumor cell line. PMID:25814916

  11. Natural Analogue Synthesis Report

    SciTech Connect

    A. M. Simmons

    2002-05-01

    The purpose of this report is to present analogue studies and literature reviews designed to provide qualitative and quantitative information to test and provide added confidence in process models abstracted for performance assessment (PA) and model predictions pertinent to PA. This report provides updates to studies presented in the ''Yucca Mountain Site Description'' (CRWMS M and O 2000 [151945], Section 13) and new examples gleaned from the literature, along with results of quantitative studies conducted specifically for the Yucca Mountain Site Characterization Project (YMP). The intent of the natural analogue studies was to collect corroborative evidence from analogues to demonstrate additional understanding of processes expected to occur during postclosure at a potential Yucca Mountain repository. The report focuses on key processes by providing observations and analyses of natural and anthropogenic (human-induced) systems to improve understanding and confidence in the operation of these processes under conditions similar to those that could occur in a nuclear waste repository. The process models include those that represent both engineered and natural barrier processes. A second purpose of this report is to document the various applications of natural analogues to geologic repository programs, focusing primarily on the way analogues have been used by the YMP. This report is limited to providing support for PA in a confirmatory manner and to providing corroborative inputs for process modeling activities. Section 1.7 discusses additional limitations of this report. Key topics for this report are analogues to emplacement drift degradation, waste form degradation, waste package degradation, degradation of other materials proposed for the engineered barrier, seepage into drifts, radionuclide flow and transport in the unsaturated zone (UZ), analogues to coupled thermal-hydrologic-mechanical-chemical processes, saturated zone (SZ) transport, impact of radionuclide

  12. The impact of β-azido(or 1-piperidinyl)methylamino acids in position 2 or 3 on biological activity and conformation of dermorphin analogues.

    PubMed

    Maciejczyk, Maciej; Lasota, Anika; Frączak, Oliwia; Kosson, Piotr; Misicka, Aleksandra; Nowakowski, Michał; Ejchart, Andrzej; Olma, Aleksandra

    2016-08-01

    The synthesis of new dermorphin analogues is described. The (R)-alanine or phenylalanine residues of natural dermorphin were substituted by the corresponding α-methyl-β-azidoalanine or α-benzyl-β-azido(1-piperidinyl)alanine residues. The potency and selectivity of the new analogues were evaluated by a competitive receptor binding assay in rat brain using [(3) H]DAMGO (a μ ligand) and [(3) H]DELT (a δ ligand). The most active analogue in this series, Tyr-(R)-Ala-(R)-α-benzyl-β-azidoAla-Gly-Tyr-Pro-Ser-NH2 and its epimer were analysed by (1) H and (13) C NMR spectroscopy and restrained molecular dynamics simulations. The dominant conformation of the investigated peptides depended on the absolute configuration around C(α) in the α-benzyl-β-azidoAla residue in position 3. The (R) configuration led to the formation of a type I β-turn, whilst switching to the (S) configuration gave rise to an inverse β-turn of type I', followed by the formation of a very short β-sheet. The selectivity of Tyr-(R)-Ala-(R) and (S)-α-benzyl-β-azidoAla-Gly-Tyr-Pro-Ser-NH2 was shown to be very similar; nevertheless, the two analogues exhibited different conformational preferences. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. PMID:27443980

  13. Intermolecular interaction of voriconazole analogues with model membrane by DSC and NMR, and their antifungal activity using NMR based metabolic profiling.

    PubMed

    Kalamkar, Vaibhav; Joshi, Mamata; Borkar, Varsha; Srivastava, Sudha; Kanyalkar, Meena

    2013-11-01

    The development of novel antifungal agents with high susceptibility and increased potency can be achieved by increasing their overall lipophilicity. To enhance the lipophilicity of voriconazole, a second generation azole antifungal agent, we have synthesized its carboxylic acid ester analogues, namely p-methoxybenzoate (Vpmb), toluate (Vtol), benzoate (Vbz) and p-nitrobenzoate (Vpnb). The intermolecular interactions of these analogues with model membrane have been investigated using nuclear magnetic resonance (NMR) and differential scanning calorimetric (DSC) techniques. The results indicate varying degree of changes in the membrane bilayer's structural architecture and physico-chemical characteristics which possibly can be correlated with the antifungal effects via fungal membrane. Rapid metabolite profiling of chemical entities using cell preparations is one of the most important steps in drug discovery. We have evaluated the effect of synthesized analogues on Candida albicans. The method involves real time (1)H NMR measurement of intact cells monitoring NMR signals from fungal metabolites which gives Metabolic End Point (MEP). This is then compared with Minimum Inhibitory Concentration (MIC) determined using conventional methods. Results indicate that one of the synthesized analogues, Vpmb shows reasonably good activity.

  14. The impact of β-azido(or 1-piperidinyl)methylamino acids in position 2 or 3 on biological activity and conformation of dermorphin analogues.

    PubMed

    Maciejczyk, Maciej; Lasota, Anika; Frączak, Oliwia; Kosson, Piotr; Misicka, Aleksandra; Nowakowski, Michał; Ejchart, Andrzej; Olma, Aleksandra

    2016-08-01

    The synthesis of new dermorphin analogues is described. The (R)-alanine or phenylalanine residues of natural dermorphin were substituted by the corresponding α-methyl-β-azidoalanine or α-benzyl-β-azido(1-piperidinyl)alanine residues. The potency and selectivity of the new analogues were evaluated by a competitive receptor binding assay in rat brain using [(3) H]DAMGO (a μ ligand) and [(3) H]DELT (a δ ligand). The most active analogue in this series, Tyr-(R)-Ala-(R)-α-benzyl-β-azidoAla-Gly-Tyr-Pro-Ser-NH2 and its epimer were analysed by (1) H and (13) C NMR spectroscopy and restrained molecular dynamics simulations. The dominant conformation of the investigated peptides depended on the absolute configuration around C(α) in the α-benzyl-β-azidoAla residue in position 3. The (R) configuration led to the formation of a type I β-turn, whilst switching to the (S) configuration gave rise to an inverse β-turn of type I', followed by the formation of a very short β-sheet. The selectivity of Tyr-(R)-Ala-(R) and (S)-α-benzyl-β-azidoAla-Gly-Tyr-Pro-Ser-NH2 was shown to be very similar; nevertheless, the two analogues exhibited different conformational preferences. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  15. Synthesis and biological activity of chiral tetrahydrofuranyl amino acids as building moieties of pamamycin analogues.

    PubMed

    Krüger-Velthusen, E; Jütten, P; Grigoriev, P A; Gräfe, U

    2002-01-01

    A new synthetic route to chiral tetrahydrofuranyl amino acids is described starting with D-glucose. The 17-step and a 20-step procedures, respectively, furnished compounds of the general formulas 1 and 2 mimicking the dimethylamino carboxylic acid part of pamamycin (3). In comparison with the absolute stereochemistry of 3 the acyclic compounds 1a-c and 2a-c are enantiomers. Despite of the presence of a dimethylamino function they showed neither antibacterial activity nor protonophoric effects on an artificial bilayer membrane suggesting that the macrodiolide ring of 3 forms an indispensable prerequisite for the known interaction of this antibiotic with biological systems.

  16. Activation of Metabotropic Glutamate Receptor 7 Is Required for Induction of Long-Term Potentiation at SC-CA1 Synapses in the Hippocampus

    PubMed Central

    Klar, Rebecca; Walker, Adam G.; Ghose, Dipanwita; Grueter, Brad A.; Engers, Darren W.; Hopkins, Corey R.; Lindsley, Craig W.; Xiang, Zixiu

    2015-01-01

    Of the eight metabotropic glutamate (mGlu) receptor subtypes, only mGlu7 is expressed presynaptically at the Schaffer collateral (SC)-CA1 synapse in the hippocampus in adult animals. Coupled with the inhibitory effects of Group III mGlu receptor agonists on transmission at this synapse, mGlu7 is thought to be the predominant autoreceptor responsible for regulating glutamate release at SC terminals. However, the lack of mGlu7-selective pharmacological tools has hampered direct testing of this hypothesis. We used a novel, selective mGlu7-negative allosteric modulator (NAM), ADX71743, and a newly described Group III mGlu receptor agonist, LSP4-2022, to elucidate the role of mGlu7 in modulating transmission in hippocampal area CA1 in adult C57BL/6J male mice. Interestingly, although mGlu7 agonists inhibit SC-CA1 EPSPs, we found no evidence for activation of mGlu7 by stimulation of SC-CA1 afferents. However, LSP4-2022 also reduced evoked monosynaptic IPSCs in CA1 pyramidal cells and, in contrast to its effect on SC-CA1 EPSPs, ADX71743 reversed the ability of high-frequency stimulation of SC afferents to reduce IPSC amplitudes. Furthermore, blockade of mGlu7 prevented induction of LTP at the SC-CA1 synapse and activation of mGlu7 potentiated submaximal LTP. Together, these data suggest that mGlu7 serves as a heteroreceptor at inhibitory synapses in area CA1 and that the predominant effect of activation of mGlu7 by stimulation of glutamatergic afferents is disinhibition, rather than reduced excitatory transmission. Furthermore, this mGlu7-mediated disinhibition is required for induction of LTP at the SC-CA1 synapse, suggesting that mGlu7 could serve as a novel therapeutic target for treatment of cognitive disorders. PMID:25972184

  17. Fear potentiated startle increases phospholipase D (PLD) expression/activity and PLD-linked metabotropic glutamate receptor mediated post-tetanic potentiation in rat amygdala.

    PubMed

    Krishnan, Balaji; Scott, Michael T; Pollandt, Sebastian; Schroeder, Bradley; Kurosky, Alexander; Shinnick-Gallagher, Patricia

    2016-02-01

    Long-term memory (LTM) of fear stores activity dependent modifications that include changes in amygdala signaling. Previously, we identified an enhanced probability of release of glutamate mediated signaling to be important in rat fear potentiated startle (FPS), a well-established translational behavioral measure of fear. Here, we investigated short- and long-term synaptic plasticity in FPS involving metabotropic glutamate receptors (mGluRs) and associated downstream proteomic changes in the thalamic-lateral amygdala pathway (Th-LA). Aldolase A, an inhibitor of phospholipase D (PLD), expression was reduced, concurrent with significantly elevated PLD protein expression. Blocking the PLD-mGluR signaling significantly reduced PLD activity. While transmitter release probability increased in FPS, PLD-mGluR agonist and antagonist actions were occluded. In the unpaired group (UNP), blocking the PLD-mGluR increased while activating the receptor decreased transmitter release probability, consistent with decreased synaptic potentials during tetanic stimulation. FPS Post-tetanic potentiation (PTP) immediately following long-term potentiation (LTP) induction was significantly increased. Blocking PLD-mGluR signaling prevented PTP and reduced cumulative PTP probability but not LTP maintenance in both groups. These effects are similar to those mediated through mGluR7, which is co-immunoprecipitated with PLD in FPS. Lastly, blocking mGluR-PLD in the rat amygdala was sufficient to prevent behavioral expression of fear memory. Thus, our study in the Th-LA pathway provides the first evidence for PLD as an important target of mGluR signaling in amygdala fear-associated memory. Importantly, the PLD-mGluR provides a novel therapeutic target for treating maladaptive fear memories in posttraumatic stress and anxiety disorders.

  18. Synthesis and Anti-HCV Activity of 4-Hydroxyamino α-Pyranone Carboxamide Analogues

    PubMed Central

    2013-01-01

    High genetic variability in hepatitis C virus (HCV), emergence of drug resistant viruses and side effects demand the requirement for development of new scaffolds to show an alternate mechanism. Herein, we report discovery of new scaffold I based on 4-hydroxyamino α-pyranone carboxamide as promising anti-HCV agents. A comprehensive structure–activity relationship (SAR) was explored with several newly synthesized compounds. In all promising compounds (17–19, 21–22, 24–25, and 49) with EC50 ranging 0.15 to 0.40 μM, the aryl group at C-6 position of α-pyranone were unsubstituted. In particular, 25 demonstrated potential anti-HCV activity with EC50 of 0.18 μM in cell based HCV replicon system with lower cytotoxicity (CC50 > 20 μM) and provided a new scaffold for anti-HCV drug development. Further investigations, including biochemical characterization, are yet to be performed to elucidate its possible mode of action. PMID:24900815

  19. Novel synthesized 2, 4-DAPG analogues: antifungal activity, mechanism and toxicology.

    PubMed

    Gong, Liang; Tan, Haibo; Chen, Feng; Li, Taotao; Zhu, Jianyu; Jian, Qijie; Yuan, Debao; Xu, Liangxiong; Hu, Wenzhong; Jiang, Yueming; Duan, Xuewu

    2016-01-01

    2, 4-Diacetylphloroglucinol (2,4-DAPG), a natural phenolic compound, has been investigated in light of its biological activities against plant pathogens. To improve its potential application, fourteen 2,4-DAPG analogous were synthesized through the Friedel-Crafts reaction using acyl chlorides and phloroglucinol. Of the 2,4-DAPG derivatives, MP4 exhibited much higher antifungal activity against Penicillium digitatum and P. italicum, the major pathogenic fungi in citrus fruit, than 2, 4-DAPG in vitro, and significantly inhibited the development of decay in harvested mandarin (Citrus reticulata Blanco cv. Shatang.) fruit in vivo. It was found that MP4 resulted in the wrinkle of the hyphae in both fungi with serious folds and breakage. In addition, the expression of several cytochrome P450 (CYP) genes were also modified in both fungi by MP4, which might be associated with the disorder of cell membrane formation. Furthermore, the toxicology of MP4 by evaluating the cell proliferation effect on human normal lung epithelial (16HBE) and kidney 293 (HEK293) cells, was significantly lower than that of albesilate, a widely used fungicide in harvested citrus fruit. In summary, the synthesized MP4 has shown a great potential as a novel fungicide that might be useful for control of postharvest decay in citrus fruit. PMID:27562341

  20. Design, synthesis and antitrypanosomal activity of some nitrofurazone 1,2,4-triazolic bioisosteric analogues.

    PubMed

    Silva, Fredson T; Franco, Caio H; Favaro, Denize C; Freitas-Junior, Lucio H; Moraes, Carolina B; Ferreira, Elizabeth I

    2016-10-01

    Chagas disease, caused by Trypanosoma cruzi, is a parasitosis that predominates in Latin America. It is estimated that 25 million people are under the risk of infection and, in 2008, more than 10 thousand deaths were registered. The only two drugs available in the therapeutics, nifurtimox and benznidazole, showed to be more effective in the acute phase of the disease. However, there is no standard treatment protocol effective for the chronic phase. Nitrofurazone (NF), an antimicrobial drug, has activity against T. cruzi, although being toxic. Considering the need for new antichagasic drugs, the existence of promising new therapeutic targets, as 14α-sterol demethylase and cruzain, and employing the bioisosterism and molecular hybridization approaches, four novel compounds were synthesized, characterized by melting point range, elemental analysis, IR and NMR spectroscopy. The compounds were tested against T. cruzi amastigotes in infected U2OS cells. All compounds showed selectivity towards T. cruzi and showed trypanomicidal activity in low micromolar range. The compound 3 showed potency similar to benznidazole, but lower efficacy. These results highlight the importance of the 1,2,4-triazole, thiosemicarbazonic and nitro group moieties for designing new efficient compounds, potentially for the chronic phase of Chagas disease. PMID:27318979

  1. Novel synthesized 2, 4-DAPG analogues: antifungal activity, mechanism and toxicology

    PubMed Central

    Gong, Liang; Tan, Haibo; Chen, Feng; Li, Taotao; Zhu, Jianyu; Jian, Qijie; Yuan, Debao; Xu, Liangxiong; Hu, Wenzhong; Jiang, Yueming; Duan, Xuewu

    2016-01-01

    2, 4-Diacetylphloroglucinol (2,4-DAPG), a natural phenolic compound, has been investigated in light of its biological activities against plant pathogens. To improve its potential application, fourteen 2,4-DAPG analogous were synthesized through the Friedel-Crafts reaction using acyl chlorides and phloroglucinol. Of the 2,4-DAPG derivatives, MP4 exhibited much higher antifungal activity against Penicillium digitatum and P. italicum, the major pathogenic fungi in citrus fruit, than 2, 4-DAPG in vitro, and significantly inhibited the development of decay in harvested mandarin (Citrus reticulata Blanco cv. Shatang.) fruit in vivo. It was found that MP4 resulted in the wrinkle of the hyphae in both fungi with serious folds and breakage. In addition, the expression of several cytochrome P450 (CYP) genes were also modified in both fungi by MP4, which might be associated with the disorder of cell membrane formation. Furthermore, the toxicology of MP4 by evaluating the cell proliferation effect on human normal lung epithelial (16HBE) and kidney 293 (HEK293) cells, was significantly lower than that of albesilate, a widely used fungicide in harvested citrus fruit. In summary, the synthesized MP4 has shown a great potential as a novel fungicide that might be useful for control of postharvest decay in citrus fruit. PMID:27562341

  2. Broad-spectrum antiviral activity of carbodine, the carbocyclic analogue of cytidine.

    PubMed

    De Clercq, E; Bernaerts, R; Shealy, Y F; Montgomery, J A

    1990-01-15

    Carbocyclic cytidine (C-Cyd) is a broad-spectrum antiviral agent active against DNA viruses [pox (vaccinia)], (+)RNA viruses [toga (Sindbis, Semliki forest), corona], (-)RNA viruses [orthomyxo (influenza), paramyxo (parainfluenza, measles), rhabdo (vesicular stomatitis)] and (+/-)RNA viruses (reo). The target enzyme of C-Cyd is supposed to be CTP synthetase that converts UTP to CTP. In keeping with this assumption are the observations that (i) C-Cyd effects a dose-dependent inhibition of RNA synthesis in both virus-infected and uninfected cells, and (ii) exogenous addition of either Urd or Cyd reverses both the antiviral and cytocidal activity of C-Cyd, whereas addition of dThd or dCyd fails to do so. The selectivity of C-Cyd against Sindbis, vesicular stomatitis and reo virus is markedly increased when C-Cyd is combined with Cyd (10 micrograms/mL). This combination may therefore be worth pursuing as a chemotherapeutic modality for the treatment of virus infections. PMID:1689159

  3. Total synthesis and biological activity of marine alkaloid Eudistomins Y1-Y7 and their analogues.

    PubMed

    Jin, Huijuan; Zhang, Puyong; Bijian, Krikor; Ren, Sumei; Wan, Shengbiao; Alaoui-Jamali, Moulay A; Jiang, Tao

    2013-05-01

    Eudistomin Y class compounds are a series of β-carbolines which was originally isolated from a marine turnicate or ascidian near the South Korea Sea. These compounds contain bromo-substituted groups, which is one of the typical characters of marine natural products. We report herein the chemical synthesis and biological evaluation of seven new β-carboline-based metabolites, Eudistomins Y1-Y7, and their hydroxyl-methylated phenyl derivatives. Using bromo-substituted tryptamines and bromo-substituted phenylglyoxals as the key intermediates, Eudistomins Y1-Y7 and their derivatives were synthesized via the acid-catalyzed Pictet-Spengler reaction and fully characterized by 1H- and 13C-NMR and mass spectroscopy. Biological studies revealed that all of the compounds showed moderate growth inhibitory activity against breast carcinoma cell line MDA-231 with IC50 of 15-63 μM and the inhibitory activities of hydroxyl-methylated phenyl products were higher than that of the corresponding natural products Eudistomins Y1-Y7.

  4. Ginkgo biloba Extract (EGb 761®) Inhibits Glutamate-induced Up-regulation of Tissue Plasminogen Activator Through Inhibition of c-Fos Translocation in Rat Primary Cortical Neurons.

    PubMed

    Cho, Kyu Suk; Lee, Ian Myungwon; Sim, Seobo; Lee, Eun Joo; Gonzales, Edson Luck; Ryu, Jong Hoon; Cheong, Jae Hoon; Shin, Chan Young; Kwon, Kyoung Ja; Han, Seol-Heui

    2016-01-01

    EGb 761(®) , a standardized extract of Ginkgo biloba leaves, has antioxidant and antiinflammatory properties in experimental models of neurodegenerative disorders such as stroke and Alzheimer's disease. Tissue plasminogen activator (tPA) acts a neuromodulator and plays a crucial role in the manifestation of neurotoxicity leading to exaggerated neuronal cell death in neurological insult conditions. In this study, we investigated the effects of EGb 761 on the basal and glutamate-induced activity and expression of tPA in rat primary cortical neurons. Under basal condition, EGb 761 inhibited both secreted and cellular tPA activities, without altering tPA mRNA level, as modulated by the activation of p38. Compared with basal condition, EGb 761 inhibited the glutamate-induced up-regulation of tPA mRNA resulting in the normalization of overt tPA activity and expression. c-Fos is a component of AP-1, which plays a critical role in the modulation of tPA expression. Interestingly, EGb 761 inhibited c-Fos nuclear translocation without affecting c-Fos expression in glutamate-induced rat primary cortical neurons. These results demonstrated that EGb 761 can modulate tPA activity under basal and glutamate-stimulated conditions by both translational and transcriptional mechanisms. Thus, EGb 761 could be a potential and effective therapeutic strategy in tPA-excessive neurotoxic conditions.

  5. In silico approaches to identify the potential inhibitors of glutamate carboxypeptidase II (GCPII) for neuroprotection.

    PubMed

    Naushad, Shaik Mohammad; Janaki Ramaiah, M; Stanley, Balraj Alex; Prasanna Lakshmi, S; Vishnu Priya, J; Hussain, Tajamul; Alrokayan, Salman A; Kutala, Vijay Kumar

    2016-10-01

    To develop a potential inhibitor for glutamate carboxypeptidase II (GCPII) effective against all the eight common genetic variants reported, PyMOL molecular visualization system was used to generate models of variants using the crystal structure of GCPII i.e. 2OOT as a template. High-throughput virtual screening of 29 compounds revealed differential efficacy across the eight genetic variants (pIC50: 4.70 to 10.22). Pharmacophore analysis and quantitative structure-activity relationship (QSAR) studies revealed a urea-based N-acetyl aspartyl glutamate (NAAG) analogue as more potent inhibitor, which was effective across all the genetic variants of GCPII as evidenced by glide scores (-4.32 to -7.08) and protein-ligand interaction plots (13 interactions in wild GCPII). This molecule satisfied Lipinski rule of five and rule of three for drug-likeliness. Being a NAAG-analogue, this molecule might confer neuroprotection by inhibiting glutamatergic neurotransmission mediated by N-acetylated alpha-linked acidic dipeptidase (NAALADase), a splice variant of GCPII. PMID:27430729

  6. Monoamine Oxidase Inhibitory Activity of Novel Pyrazoline Analogues: Curcumin Based Design and Synthesis.

    PubMed

    Badavath, Vishnu Nayak; Baysal, İpek; Ucar, Gulberk; Sinha, Barij Nayan; Jayaprakash, Venkatesan

    2016-01-14

    A series of new 2-methoxy-4-(5-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenolderivatives, 4-13, were synthesized and tested for their human MAO inhibitory activity. All the compounds were found to be selective and reversible toward hMAO-A except 4, a selective inhibitor of hMAO-B and 12, a nonselective inhibitor. Compound 7 was found to be a potent inhibitor of hMAO-A with Ki = 0.06 ± 0.003 μM and was having selectivity index of (SI = 1.02 × 10(-5)). It was found to be better than standard drug, Moclobemide (hMAO-A with Ki = 0.11 ± 0.01 μM) with selectivity index of SI = 0.049. Molecular docking simulation was carried out to understand the crucial interactions responsible for selectivity and potency. PMID:26819666

  7. Novel di-aryl-substituted isoxazoles act as noncompetitive inhibitors of the system Xc(-) cystine/glutamate exchanger.

    PubMed

    Newell, J L; Keyari, C M; McDaniel, S W; Diaz, P J; Natale, N R; Patel, S A; Bridges, R J

    2014-07-01

    The system xc(-) antiporter is a plasma membrane transporter that mediates the exchange of extracellular l-cystine with intracellular l-glutamate. This exchange is significant within the context of the CNS because the import of l-cystine is required for the synthesis of the antioxidant glutathione, while the efflux of l-glutamate has the potential to contribute to either excitatory signaling or excitotoxic pathology. Changes in the activity of the transport system have been linked to the underlying pathological mechanisms of a variety of CNS disorders, one of the most prominent of which is its highly enriched expression in glial brain tumors. In an effort to produce more potent system xc(-) blockers, we have been using amino-3-carboxy-5-methylisoxazole propionic acid (ACPA) as a scaffold for inhibitor development. We previously demonstrated that the addition of lipophilic aryl groups to either the #4 or #5 position on the isoxazole ring markedly increased the inhibitory activity at system xc(-). In the present work a novel series of analogues has been prepared in which aryl groups have been introduced at both the #4 and #5 positions. In contrast to the competitive action of the mono-substituted analogues, kinetic analyses indicate that the di-substituted isoxazoles block system xc(-)-mediated uptake of (3)H-l-glutamate into SNB-19 cells by a noncompetitive mechanism. These new analogues appear to be the first noncompetitive inhibitors identified for this transport system, as well as being among the most potent blockers identified to date. These diaryl-isoxazoles should be of value in assessing the physiological roles and molecular pharmacology of system xc(-).

  8. Activity profiles of dalargin and its analogues in mu-, delta- and kappa-opioid receptor selective bioassays.

    PubMed

    Pencheva, N; Pospisek, J; Hauzerova, L; Barth, T; Milanov, P

    1999-10-01

    1. To elucidate the structural features ensuring action of [D-Ala2, Leu5]-enkephalyl-Arg (dalargin), a series of dalargin analogues were tested for their effectiveness in depressing electrically-evoked contractions of the guinea-pig myenteric plexus-longitudinal muscle preparations (mu- and kappa-opioid receptors) and the vasa deferentia of the hamster (delta-opioid receptors), mouse (mu-, delta- and kappa-opioid receptors), rat (similar to mu-opioid receptors) and rabbit (kappa-opioid receptors). The naloxone KB values in the myenteric plexus were also obtained. 2. [L-Ala2]-dalargin was 19 times less potent than dalargin, and its pharmacological activity was peptidase-sensitive. The ratio of delta-activity to mu-activity for [L-Ala2]-dalargin was 6.78, and KB was 7.9 nM. This emphasizes the role that D-configuration of Ala2 plays in determining the active folding of dalargin molecule as well as in conferring resistance to peptidases. 3. [Met5]-dalargin was equipotent to dalargin in the myenteric plexus, but was more potent in the vasa deferentia of hamster and mouse (KB=5.5 nM). Leu5 and the interdependence of Leu5 and D-Ala2 are of importance for the selectivity of dalargin for mu-opioid receptors. 4. Dalarginamide was more potent and selective for mu-opioid receptors than dalargin, whilst dalarginethylamide, though equipotent to dalarginamide in the myenteric plexus, was more potent at delta-opioid receptors (KB=5.0 nM). [D-Phe4]-dalarginamide and N-Me-[D-Phe4]-dalarginamide were inactive indicating the contribution of L-configuration of Phe4 to the pharmacological potency of dalargin. 5. N-Me-[L-Phe4]-dalarginamide possessed the highest potency and selectivity for mu-opioid receptors (the ratio of delta-activity to mu-activity was 0.00053; KB=2.6 nM). The CONH2 terminus combined with the N-methylation of L-Phe4 increased the potency and selectivity of dalargin for mu-opioid receptors.

  9. Activity profiles of dalargin and its analogues in μ-, δ- and κ-opioid receptor selective bioassays

    PubMed Central

    Pencheva, Nevena; Pospišek, Jan; Hauzerova, Linda; Barth, Tomislav; Milanov, Peter

    1999-01-01

    To elucidate the structural features ensuring action of [D-Ala2, Leu5]-enkephalyl-Arg (dalargin), a series of dalargin analogues were tested for their effectiveness in depressing electrically-evoked contractions of the guinea-pig myenteric plexus-longitudinal muscle preparations (μ- and κ-opioid receptors) and the vasa deferentia of the hamster (δ-opioid receptors), mouse (μ-, δ- and κ-opioid receptors), rat (similar to μ-opioid receptors) and rabbit (κ-opioid receptors). The naloxone KB values in the myenteric plexus were also obtained.[L-Ala2]-dalargin was 19 times less potent than dalargin, and its pharmacological activity was peptidase-sensitive. The ratio of δ-activity to μ-activity for [L-Ala2]-dalargin was 6.78, and KB was 7.9 nM. This emphasizes the role that D-configuration of Ala2 plays in determining the active folding of dalargin molecule as well as in conferring resistance to peptidases.[Met5]-dalargin was equipotent to dalargin in the myenteric plexus, but was more potent in the vasa deferentia of hamster and mouse (KB=5.5 nM). Leu5 and the interdependence of Leu5 and D-Ala2 are of importance for the selectivity of dalargin for μ-opioid receptors.Dalarginamide was more potent and selective for μ-opioid receptors than dalargin, whilst dalarginethylamide, though equipotent to dalarginamide in the myenteric plexus, was more potent at δ-opioid receptors (KB=5.0 nM). [D-Phe4]-dalarginamide and N-Me-[D-Phe4]-dalarginamide were inactive indicating the contribution of L-configuration of Phe4 to the pharmacological potency of dalargin.N-Me-[L-Phe4]-dalarginamide possessed the highest potency and selectivity for μ-opioid receptors (the ratio of δ-activity to μ-activity was 0.00053; KB=2.6 nM). The CONH2 terminus combined with the N-methylation of L-Phe4 increased the potency and selectivity of dalargin for μ-opioid receptors. PMID:10516634

  10. Transferred nuclear Overhauser effect analyses of membrane-bound enkephalin analogues by sup 1 H nuclear magnetic resonance: Correlation between activities and membrane-bound conformations

    SciTech Connect

    Milon, Alain; Miyazawa, Tatsuo; Higashijima, Tsutomu )

    1990-01-09

    Leu-enkephalin, (D-Ala{sup 2})Leu-enkephalin, and (D-Ala{sup 2})Leu-enkephalinamide (agonists) and (L-Ala{sup 2})Leu-enkephalin (inactive analogue) bind to lipid bilayer consisting of phosphatidylcholine and phosphatidylserine. The conformations that these compounds assume, once bound to perdeuterated phospholipid bilayer, have been shown to be unique, as shown by the transferred nuclear Overhauser effect (TRNOE) of {sup 1}H NMR spectroscopy. In addition, their location in the bilayer was analyzed by TRNOE in the presence of spin-labeled phospholipids. These analyses showed a clear relationship between the activity and the peptide-membrane interaction. The three active peptides, when bound to membranes, adopt the same conformation, characterized by a type II{prime} {beta}-turn around Gly{sup 3}-Phe and a {gamma}-turn around Gly{sup 2} (or D-Ala{sup 2}). The inactive analogue, (L-Ala{sup 2})Leu-enkephalin, displayed a completely different TRNOE pattern corresponding to a different conformation in the membrane-bound state. The tyrosine residue of the active compounds is not inserted into the interior of membrane, but it is inserted into the bilayer for the L-Ala{sup 2} analogue. According to these results, (L-Ala{sup 2})Leu-enkephalin may be explained to be inactive because the mode of binding to the membranes is different from that of active compounds.

  11. Adaptation of methods for glutamate dehydrogenase and alcohol dehydrogenase activities to a centrifugal analyser: assessment of their clinical use in anoxic states of the liver.

    PubMed Central

    Shephard, M D; Penberthy, L A; Berry, M N

    1987-01-01

    Sensitive, precise, and rapid methods for the measurement of alcohol dehydrogenase (ADH) and glutamate dehydrogenase (GDH) were developed on the Cobas Bio centrifugal analyser. The optimal pH for ADH in caucasians was 9.8. Non-linearity of ADH enzyme activity was observed when samples were diluted in saline; linearity was restored when inactivated serum was used as diluent. ADH was shown to be a sensitive index of liver anoxia due to cardiorespiratory disturbance (clinical sensitivity 90%) and generalised anoxia. GDH exhibited sensitivity equal to that of alanine aminotransferase (ALT) but was inferior to gamma-glutamyltransferase (GGT) in the detection of specific liver disease. Both ADH and GDH were sensitive indicators of alcoholic liver disease. PMID:2890662

  12. Srchi24, A Chitinase Homolog Lacking an Essential Glutamic Acid Residue for Hydrolytic Activity, Is Induced during Nodule Development on Sesbania rostrata1

    PubMed Central

    Goormachtig, Sofie; Van de Velde, Willem; Lievens, Sam; Verplancke, Christa; Herman, Sylvia; De Keyser, Annick; Holsters, Marcelle

    2001-01-01

    The interaction between the tropical legume Sesbania rostrata and the bacterium Azorhizobium caulinodans results in the formation of nodules on both stem and roots. Stem nodulation was used as a model system to isolate early markers by differential display. One of them, Srchi24 is a novel early nodulin whose transcript level increased already 4 h after inoculation. This enhancement depended on Nod factor-producing bacteria. Srchi24 transcript levels were induced also by exogenous cytokinins. In situ hybridization and immunolocalization experiments showed that Srchi24 transcripts and proteins were present in the outermost cortical cell layers of the developing nodules. Sequence analyses revealed that Srchi24 is similar to class III chitinases, but lacks an important catalytic glutamate residue. A fusion between a maltose-binding protein and Srchi24 had no detectable hydrolytic activity. A function in nodulation is proposed for the Srchi24 protein. PMID:11553736

  13. Spinal actions of substance P analogues on cardiovascular responses in the rat: a structure-activity analysis.

    PubMed

    Couture, R; Gupta, A; Kérouac, R; Escher, E; Regoli, D

    1987-03-01

    Ten substance P (SP) analogues were tested for their effects on mean arterial pressure and heart rate following intrathecal administration in the pentobarbital anaesthetized rat. The 10 analogues are [D-Pro4,D-alpha Npa7,9,10]SP(4-11) (A-I), (D-alpha Npa7,9,10]SP (A-II), [D-Trp7,9,10]SP (A-III), [D-Pro4,D-Npa7,9,Phe11]SP(4-11) (A-IV), [D-Pro4,D-beta Npa7,D-alpha Npa9,D-Phe11]SP(4-11) (A-V), [D-Pro4,Lys6,D-Trp7,9,10,Phe11]SP(4-11) (A-VI), [D-Pro4,D-Trp7,9,10,Phe11]SP(4-11) (A-VII), [D-Pro4,D-Trp7,9,10,Trp11]SP(4-11) (A-VIII), [D-Trp7,9,10,Trp11]SP (A-IX), and [D-Pro4,D-Phe7,9,10,Phe11]SP(4-11) (A-X). At 6.5 nmol, the analogues containing the amino acid D-Npa (A-I, A-II, A-IV, and A-V) or D-Phe (A-X) in positions 7, 9, or 10 of SP or its C-terminal octapeptide are devoid of the long-lasting cardio- and vaso-depressor effects, which are otherwise seen with analogues containing the amino acid D-Trp (A-III, A-VI, A-VII, A-VIII, and A-IX) in the same positions. Some of the analogues containing D-Npa maintain the initial hypotensive effect seen with SP while the analogue containing D-Phe produces only a small hypertensive response. The 10 analogues when tested at a dose that failed to alter basal mean arterial pressure and heart rate did not block the cardiovascular responses elicited by SP and no cross desensitization was observed between SP and these analogues. It appears that these SP analogues exert cardiovascular effects in the rat spinal cord probably without interacting with SP receptors.

  14. Neuroprotective properties of nootropic dipeptide GVS-111 in in vitro oxygen-glucose deprivation, glutamate toxicity and oxidative stress.

    PubMed

    Andreeva, N A; Stel'mashuk, E V; Isaev, N K; Ostrovskaya, R U; Gudasheva, T A; Viktorov, I V

    2000-10-01

    Argon anoxia and glucose deprivation were used for modeling of ischemic damage in the cultures of cerebellar granule cells. Protective effect of peptide piracetam analogue GVS-111 was demonstrated. GVS-111 prevented neurodegeneration induced by glutamate and oxidative stress. In contrast to GVS-111, piracetam did not attenuate neurocytotoxic effect of glutamate. PMID:11177296

  15. Glutamic acid decarboxylase activity is stimulated in quail retina neuronal cells transformed by Rous sarcoma virus and is regulated by pp60v-src.

    PubMed Central

    Crisanti, P; Lorinet, A M; Calothy, G; Pessac, B

    1985-01-01

    Rous sarcoma virus (RSV) stimulates in quail embryo neuro-retina (NR) cultures the specific activity of glutamic acid decarboxylase (GAD), the enzyme responsible for the synthesis of gamma-aminobutyric acid, a major inhibitory neurotransmitter in NR and in central nervous system. In quail embryo NR cultures transformed by ts NY-68, a thermodependent transformation-defective mutant of RSV, stimulation of GAD activity is regulated by pp60v-src, the product of the src gene of RSV. Fibroblasts and myoblasts have a very low GAD activity that is not stimulated after transformation by RSV. Neuronal clones, previously derived from ts NY-68-transformed established NR cell lines, have a high GAD activity which is regulated by pp60v-src, while other clones have a low GAD activity apparently not regulated by pp60v-src. These data indicate that pp60v-src selectively activates the expression of GAD in distinct neuronal cells of quail embryo NR cultures transformed by RSV. GAD activity is also stimulated in NR cells infected with viruses containing v-mil. PMID:2992933

  16. Capsaicinoids but not their analogue capsinoids lower plasma cholesterol and possess beneficial vascular activity.

    PubMed

    Huang, Weihuan; Cheang, Wai San; Wang, Xiaobo; Lei, Lin; Liu, Yuwei; Ma, Ka Ying; Zheng, Fangrui; Huang, Yu; Chen, Zhen-Yu

    2014-08-20

    Capsaicinoids exist in chili peppers, whereas capsinoids are present in some sweet peppers. The present study investigated the effects of capsaicinoids and capsinoids on plasma lipids, relaxation of the aorta, atherosclerotic plaque development, and fecal sterol excretion in hamsters fed a high-cholesterol diet. Five groups of male hamsters were given the control diet or one of the four experimental diets containing 1.3 mmol of capsaicinoids (NL), 2.6 mmol of capsaicinoids (NH), 1.3 mmol of capsinoids (OL), or 2.6 mmol of capsinoids (OH), respectively. Results showed capsaicinoids but not capsinoids could decrease plasma total cholesterol (TC), reduce the formation of atherosclerotic plaque, and relax the aortic artery. This was accompanied by a 28-175% increase in fecal excretion of acidic sterols in hamsters fed the diets containing capsaicinoids. Similarly, capsaicinoids but not capsinoids could decrease the pad weights of epididymal and prerenal adipose tissues. It was concluded that capsaicinoids but not capsinoids could favorably modulate plasma lipids and possess beneficial vascular activity. PMID:25078570

  17. Oxidative metabolism of ferrocene analogues of tamoxifen: characterization and antiproliferative activities of the metabolites.

    PubMed

    Richard, Marie-Aude; Hamels, Didier; Pigeon, Pascal; Top, Siden; Dansette, Patrick M; Lee, Hui Zhi Shirley; Vessières, Anne; Mansuy, Daniel; Jaouen, Gérard

    2015-06-01

    Ferrociphenols have been found to have high antiproliferative activity against estrogen-independent breast cancer cells. The rat and human liver microsome-mediated metabolism of three compounds of the ferrocifen (FC) family, 1,1-bis(4-hydroxyphenyl)-2-ferrocenyl-but-1-ene (FC1), 1-(4-hydroxyphenyl)-1-(phenyl)-2-ferrocenyl-but-1-ene (FC2), and 1-[4-(3-dimethylaminopropoxy)phenyl]-1-(4-hydroxyphenyl)-2-ferrocenyl-but-1-ene (FC3), was studied. Three main metabolite classes were identified: quinone methides (QMs) deriving from two-electron oxidation of FCs, cyclic indene products (CPs) deriving from acid-catalyzed cyclization of QMs, and allylic alcohols (AAs) deriving from hydroxylation of FCs. These metabolites are generated by cytochromes P450 (P450s), as shown by experiments with either N-benzylimidazole as a P450 inhibitor or recombinant human P450s. Such P450-dependent oxidation of the phenol function and hydroxylation of the allylic CH2 group of FCs leads to the formation of QM and AA metabolites, respectively. Some of the new ferrociphenols obtained in this study were found to exhibit remarkable antiproliferative effects toward MDA-MB-231 hormone-independent breast cancer cells.

  18. Capsaicinoids but not their analogue capsinoids lower plasma cholesterol and possess beneficial vascular activity.

    PubMed

    Huang, Weihuan; Cheang, Wai San; Wang, Xiaobo; Lei, Lin; Liu, Yuwei; Ma, Ka Ying; Zheng, Fangrui; Huang, Yu; Chen, Zhen-Yu

    2014-08-20

    Capsaicinoids exist in chili peppers, whereas capsinoids are present in some sweet peppers. The present study investigated the effects of capsaicinoids and capsinoids on plasma lipids, relaxation of the aorta, atherosclerotic plaque development, and fecal sterol excretion in hamsters fed a high-cholesterol diet. Five groups of male hamsters were given the control diet or one of the four experimental diets containing 1.3 mmol of capsaicinoids (NL), 2.6 mmol of capsaicinoids (NH), 1.3 mmol of capsinoids (OL), or 2.6 mmol of capsinoids (OH), respectively. Results showed capsaicinoids but not capsinoids could decrease plasma total cholesterol (TC), reduce the formation of atherosclerotic plaque, and relax the aortic artery. This was accompanied by a 28-175% increase in fecal excretion of acidic sterols in hamsters fed the diets containing capsaicinoids. Similarly, capsaicinoids but not capsinoids could decrease the pad weights of epididymal and prerenal adipose tissues. It was concluded that capsaicinoids but not capsinoids could favorably modulate plasma lipids and possess beneficial vascular activity.

  19. A conserved glutamate residue in the C-terminal deaminase domain of pentatricopeptide repeat proteins is required for RNA editing activity.

    PubMed

    Hayes, Michael L; Dang, Kim N; Diaz, Michael F; Mulligan, R Michael

    2015-04-17

    Many transcripts expressed from plant organelle genomes are modified by C-to-U RNA editing. Nuclear encoded pentatricopeptide repeat (PPR) proteins include an RNA binding domain that provides site specificity. In addition, many PPR proteins include a C-terminal DYW deaminase domain with characteristic zinc binding motifs (CXXC, HXE) and has recently been shown to bind zinc ions. The glutamate residue of the HXE motif is catalytically required in the reaction catalyzed by cytidine deaminase. In this work, we examine the activity of the DYW deaminase domain through truncation or mutagenesis of the HXE motif. OTP84 is required for editing three chloroplast sites, and transgenes expressing OTP84 with C-terminal truncations were capable of editing only one of the three cognate sites at high efficiency. These results suggest that the deaminase domain of OTP84 is required for editing two of the sites, but another deaminase is able to supply the deamination activity for the third site. OTP84 and CREF7 transgenes were mutagenized to replace the glutamate residue of the HXE motif, and transgenic plants expressing OTP84-E824A and CREF7-E554A were unable to efficiently edit the cognate editing sites for these genes. In addition, plants expressing CREF7-E554A exhibited substantially reduced capacity to edit a non-cognate site, rpoA C200. These results indicate that the DYW deaminase domains of PPR proteins are involved in editing their cognate editing sites, and in some cases may participate in editing additional sites in the chloroplast. PMID:25739442

  20. Brain glutamate decarboxylase and pyrroloquinoline quinone.

    PubMed

    Choi, S Y; Khemlani, L S; Churchich, J E

    1992-01-01

    Porcine brain glutamate decarboxylase was examined for the presence of covalently bound pyrroloquinoline quinone (PQQ). HPLC analysis of pure glutamate decarboxylase subjected to the hexanol extraction procedure gave negative results when monitored at 320 nm, the maximum of absorbance of 4-hydroxy-5-hexoxy-PQQ. Resolved glutamate decarboxylase exhibits a structureless absorption band at wavelengths longer than 300 nm which cannot be attributed to PQQ. The holoenzyme is not a pyridoxal-quinoprotein; its catalytic mechanism involves the participation of only one cofactor, i.e. pyridoxal-5-P. Free PQQ is a strong inhibitor of the decarboxylase (Ki = 13 microM) and the reaction with the protein results in spectral changes resembling those of polylysine treated with PQQ. If the concentration of free PQQ in some regions of the brain reaches the micromolar level, then PQQ might play a role in the regulation of glutamate decarboxylase activity.

  1. [Glutamate transporter dysfunction and major mental illnesses].

    PubMed

    Tanaka, Kohichi

    2016-01-01

    Glutamate is the main excitatory neurotransmitter in the central nervous system and plays an important role in most aspects of normal brain function. In spite of its importance as a neurotransmitter, excess glutamate is toxic to neurons. Clearance of extracellular glutamate is critical for maintenance of low extracellular glutamate concentration, and occurs in large part through the activity of GLT1 (EAAT2) and GLAST (EAAT1), which are primarily expressed by astrocytes. Rare variants and down-regulation of GLT1 and GLAST, in psychiatric disorders have been reported. In this review, we demonstrate that various kinds of GLT1 and/or GLAST knockout mice replicate many aspects of the behavioral abnormalities seen in major mental illnesses including schizophrenia, depression, obsessive -compulsive disorders, autism, epilepsy and addiction. PMID:26793898

  2. Ligands for Ionotropic Glutamate Receptors

    NASA Astrophysics Data System (ADS)

    Swanson, Geoffrey T.; Sakai, Ryuichi

    Marine-derived small molecules and peptides have played a central role in elaborating pharmacological specificities and neuronal functions of mammalian ionotropic glutamate receptors (iGluRs), the primary mediators of excitatory syn-aptic transmission in the central nervous system (CNS). As well, the pathological sequelae elicited by one class of compounds (the kainoids) constitute a widely-used animal model for human mesial temporal lobe epilepsy (mTLE). New and existing molecules could prove useful as lead compounds for the development of therapeutics for neuropathologies that have aberrant glutamatergic signaling as a central component. In this chapter we discuss natural source origins and pharmacological activities of those marine compounds that target ionotropic glutamate receptors.

  3. Ligands for Ionotropic Glutamate Receptors

    PubMed Central

    Swanson, Geoffrey T.; Sakai, Ryuichi

    2010-01-01

    Marine-derived small molecules and peptides have played a central role in elaborating pharmacological specificities and neuronal functions of mammalian ionotropic glutamate receptors (iGluRs), the primary mediators of excitatory synaptic transmission in the central nervous system (CNS). As well, the pathological sequelae elicited by one class of compounds (the kainoids) constitute a widely-used animal model for human mesial temporal lobe epilepsy (mTLE). New and existing molecules could prove useful as lead compounds for the development of therapeutics for neuropathologies that have aberrant glutamatergic signaling as a central component. In this chapter we discuss natural source origins and pharmacological activities of those marine compounds that target ionotropic glutamate receptors. PMID:19184587

  4. Synthesis of analogues of gingerol and shogaol, the active pungent principles from the rhizomes of Zingiber officinale and evaluation of their anti-platelet aggregation effects.

    PubMed

    Shih, Hung-Cheng; Chern, Ching-Yuh; Kuo, Ping-Chung; Wu, You-Cheng; Chan, Yu-Yi; Liao, Yu-Ren; Teng, Che-Ming; Wu, Tian-Shung

    2014-01-01

    The present study was aimed at discovering novel biologically active compounds based on the skeletons of gingerol and shogaol, the pungent principles from the rhizomes of Zingiber officinale. Therefore, eight groups of analogues were synthesized and examined for their inhibitory activities of platelet aggregation induced by arachidonic acid, collagen, platelet activating factor, and thrombin. Among the tested compounds, [6]-paradol (5b) exhibited the most significant anti-platelet aggregation activity. It was the most potent candidate, which could be used in further investigation to explore new drug leads.

  5. Activators of the Glutamate-Dependent Acid Resistance System Alleviate Deleterious Effects of YidC Depletion in Escherichia coli▿

    PubMed Central

    Yu, Zhong; Bekker, Martijn; Tramonti, Angela; Cook, Gregory M.; van Ulsen, Peter; Scheffers, Dirk-Jan; de Mattos, Joost Teixeira; De Biase, Daniela; Luirink, Joen

    2011-01-01

    The function of the essential inner membrane protein (IMP) YidC in Escherichia coli has been studied for a limited number of model IMPs and primarily using targeted approaches. These studies suggested that YidC acts at the level of insertion, folding, and quality control of IMPs, both in the context of the Sec translocon and as a separate entity. To further our understanding of YidC's role in IMP biogenesis, we screened a random overexpression library for factors that rescued the growth of cells upon YidC depletion. We found that the overexpression of the GadX and GadY regulators of the glutamate-dependent acid resistance system complemented the growth defect of YidC-depleted cells. Evidence is presented that GadXY overexpression counteracts the deleterious effects of YidC depletion on at least two fronts. First, GadXY prepares the cells for the decrease in respiratory capacity upon the depletion of YidC. Most likely, GadXY-regulated processes reduce the drop in proton-motive force that impairs the fitness of YidC-depleted cells. Second, in GadXY-overproducing cells increased levels of the general chaperone GroEL cofractionate with the inner membranes, which may help to keep newly synthesized inner membrane proteins in an insertion-competent state when YidC levels are limiting. PMID:21216990

  6. Nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate synthase expression and activity in response to different nitrogen sources in nitrogen-starved wheat seedlings.

    PubMed

    Balotf, Sadegh; Kavoosi, Gholamreza; Kholdebarin, Bahman

    2016-01-01

    The objective of this study was to examine the expression and activity of nitrate reductase (NR, EC 1.7.1.1), nitrite reductase (NiR, EC 1.7.2.2), glutamine synthetase (GS, EC 6.3.1.2), and glutamate synthase (GOGAT, EC 1.4.7.1) in response to potassium nitrate, ammonium chloride, and ammonium nitrate in nitrogen-starved wheat seedlings. Plants were grown in standard nutrient solution for 17 days and then subjected to nitrogen starvation for 7 days. The starved plants were supplied with potassium nitrate ammonium nitrate and ammonium chloride (50 mM) for 4 days and the leaves were harvested. The relative expression of NR, NiR, GS, and GOGAT as well as the enzyme activities were investigated. Nitrogen starvation caused a significant decrease both in transcript levels and in NR, NiR, GS, and GOGAT activities. Potassium nitrate and ammonium nitrate treatments restored NR, NiR, GS, and GOGAT expressions and activities. Ammonium chloride increased only the expressions and activities of GS and GOGAT in a dose-dependent manner. The results of our study highlight the differential effects between the type and the amount of nitrogen salts on NR, NiR, GS, and GOGAT activities in wheat seedlings while potassium nitrate being more effective.

  7. Effects of cyclohexanone analogues of curcumin on growth, apoptosis and NF-κB activity in PC-3 human prostate cancer cells.

    PubMed

    Wei, Xingchuan; DU, Zhi-Yun; Cui, Xiao-Xing; Verano, Michael; Mo, Rong Qing; Tang, Zhi Kai; Conney, Allan H; Zheng, Xi; Zhang, Kun

    2012-08-01

    Curcumin is a non-nutritive yellow pigment found in the spice turmeric, which is derived from the rhizome of the plant Curcuma longa Linn. Six cyclohexanone analogues of curcumin (A(1)-A(6)) were investigated for their effects on growth and apoptosis in PC-3 human prostate cancer cells. The ability of these compounds to inhibit NF-κB activity in PC-3 cells was also determined. Five out of the six curcumin analogues (A(2)-A(6)) had stronger inhibitory effects compared to curcumin on the growth of cultured PC-3 cells. Compounds A(2)-A(6) also had stronger stimulatory effects on apoptosis in PC-3 cells than curcumin, and these curcumin analogues more potently inhibited NF-κB activity than curcumin. The inhibitory effects of these compounds on NF-κB activity correlated with their effects on growth inhibition and apoptosis stimulation in PC-3 cells. The results of the present study provide a rationale for in vivo studies with A(2)-A(6) using suitable animal models of prostate cancer.

  8. Effects of cyclohexanone analogues of curcumin on growth, apoptosis and NF-κB activity in PC-3 human prostate cancer cells.

    PubMed

    Wei, Xingchuan; DU, Zhi-Yun; Cui, Xiao-Xing; Verano, Michael; Mo, Rong Qing; Tang, Zhi Kai; Conney, Allan H; Zheng, Xi; Zhang, Kun

    2012-08-01

    Curcumin is a non-nutritive yellow pigment found in the spice turmeric, which is derived from the rhizome of the plant Curcuma longa Linn. Six cyclohexanone analogues of curcumin (A(1)-A(6)) were investigated for their effects on growth and apoptosis in PC-3 human prostate cancer cells. The ability of these compounds to inhibit NF-κB activity in PC-3 cells was also determined. Five out of the six curcumin analogues (A(2)-A(6)) had stronger inhibitory effects compared to curcumin on the growth of cultured PC-3 cells. Compounds A(2)-A(6) also had stronger stimulatory effects on apoptosis in PC-3 cells than curcumin, and these curcumin analogues more potently inhibited NF-κB activity than curcumin. The inhibitory effects of these compounds on NF-κB activity correlated with their effects on growth inhibition and apoptosis stimulation in PC-3 cells. The results of the present study provide a rationale for in vivo studies with A(2)-A(6) using suitable animal models of prostate cancer. PMID:22844370

  9. Synthesis and biological activity of new series of N-modified analogues of the N/OFQ(1-13)NH2 with aminophosphonate moiety.

    PubMed

    Todorov, Petar T; Mateeva, Polina I; Zamfirova, Rositza N; Pavlov, Nikola D; Naydenova, Emilia D

    2012-09-01

    New series of N-modified analogues of the N/OFQ(1-13)NH(2) with aminophosphonate moiety have been synthesized and investigated for biological activity. These peptides were prepared by solid-phase peptide synthesis-Fmoc-strategy. The N/OFQ(1-13)NH(2) analogues were tested for agonistic activity in vitro on electrically stimulated rat vas deferens smooth-muscle preparations isolated from Wistar albino rats. Our study has shown that the selectivity of the peptides containing 1-[(methoxyphosphono)methylamino]cycloalkanecarboxylic acids to the N-side of Phe is not changed-they remain selective agonists of NOP receptors. The derivative with the largest ring (NOC-6) demonstrated efficacy similar to that of N/OFQ(1-13)NH(2), but in a 10-fold higher concentration. The agonistic activity of newly synthesized N-modified analogues of N/OFQ(1-13)NH(2) with aminophosphonate moiety was investigated for the first time.

  10. Behavioural activity of angiotensin II (3-7)4Phe--analogue of natural fragment 3-7 of angiotensin II.

    PubMed

    Hoły, Z; Wiśniewski, K; Jachimowicz, A; Braszko, J

    1996-01-01

    A study was made of the influence of pentapeptide 3-7 angiotensin II [AII(3-7)], its analogue 3-7(4)Phe [AII(3-7)4Phe] and angiotensin II (AII) on the behaviour of adult male rats. The motility, stereotypy, spatial performance, learning of conditioned and passive avoidance responses allowing to avoid aversive stimulation were estimated. Examined peptides at the dose 1 nmol injected intracerebroventricularly 15 min before the experiment did not produce specific changes in psychomotor activity in the "open field" test and in retention of the spatial task in the Morris water maze. The rate of acquisition of conditioned avoidance responses was stimulated by AII(3-7)4Phe, AII(3-7) and AII administration. In the passive avoidance situation AII improved retention of the responses whereas analogue AII(3-7)4Phe and fragment 3-7 caused similar though less pronounced effect. All the peptides applied immediately before the experiment intensified stereotypy, a behaviour evoked by of apomorphine-1 mg/kg and amphetamine-7.5 mg/kg intraperitonealy injection. These results show similar psychotropic activity of analogue AII(3-7)4Phe, comparable with the activity of natural fragment 3-7 of angiotensin II.

  11. Effects of cyclohexanone analogues of curcumin on growth, apoptosis and NF-κB activity in PC-3 human prostate cancer cells

    PubMed Central

    WEI, XINGCHUAN; DU, ZHI-YUN; CUI, XIAO-XING; VERANO, MICHAEL; MO, RONG QING; TANG, ZHI KAI; CONNEY, ALLAN H.; ZHENG, XI; ZHANG, KUN

    2012-01-01

    Curcumin is a non-nutritive yellow pigment found in the spice turmeric, which is derived from the rhizome of the plant Curcuma longa Linn. Six cyclohexanone analogues of curcumin (A1-A6) were investigated for their effects on growth and apoptosis in PC-3 human prostate cancer cells. The ability of these compounds to inhibit NF-κB activity in PC-3 cells was also determined. Five out of the six curcumin analogues (A2-A6) had stronger inhibitory effects compared to curcumin on the growth of cultured PC-3 cells. Compounds A2-A6 also had stronger stimulatory effects on apoptosis in PC-3 cells than curcumin, and these curcumin analogues more potently inhibited NF-κB activity than curcumin. The inhibitory effects of these compounds on NF-κB activity correlated with their effects on growth inhibition and apoptosis stimulation in PC-3 cells. The results of the present study provide a rationale for in vivo studies with A2-A6 using suitable animal models of prostate cancer. PMID:22844370

  12. Activation of multiple sites by adenosine analogues in the rat isolated aorta.

    PubMed Central

    Prentice, D. J.; Hourani, S. M.

    1996-01-01

    microM) E/[A] curves to NECA and CPA were right-shifted. However, no further shift of the CPA E/[A] curve was obtained when 8-SPT (50 microM) was administered concomitantly. The locations of curves to R-PIA and adenosine were unaffected by L-NAME (100 microM). 6. In the presence of PD 115,199 (0.1 microM) a parallel rightward shift of NECA E/[A] curves was observed (pA2 = 7.50 +/- 0.19). PD 115,199 (0.1 and 1 microM) gave smaller rightward shifts of E/[A] curves to R-PIA and CPA, but E/[A] curves to adenosine were not significantly shifted in the presence of PD 115,199 (0.1 or 1 microM). 7. The presence of ZM 241385 (3 nM-0.3 microM) caused parallel rightwad shifts of NECA E/[A] curves (pKB = 8.73 +/- 0.11). No significant shifts of E/[A] curves to adenosine, CPA or R-PIA were observed in the presence of 0.1 microM ZM 241385. 8. CGS 21680 (1 microM) elicited a relaxant response equivalent to approximately 40% of the NECA maximum response. In the presence of this concentration of CGS 21680, E/[A] curves to NECA were right-shifted in excess of 2-log units, whereas E/[A] curves to R-PIA were not significantly shifted. 9. BWA1433 (100 microM) caused a small but significant right-shift of the E/[A] curve to R-PIA yielding a pA2 estimate of 4.1 IB-MECA (N6-(3-iodo-benzyl)adenosine-5(1)-N-methyl uronamide) elicited relaxant responses which were resistant to blockade by 8-SPT (p[A]50 = 5.26 +/- 0.13). 10. The results suggest that whereas relaxations to NECA (10 nM-1 microM) are mediated via adenosine A2a receptors, which are located at least in part on the endothelium, R-PIA and CPA may activate A2b receptors on the endothelium and an additional, as yet undefined site, which is likely to be located on the smooth muscle and which is not susceptible to blockade by 8-SPT, PD 115,199 or ZM 241385. This site is unlikely to be an A3 receptor since the very small shift obtained in the presence of BWA1433 (100 microM), and the low potency of IB-MECA is not consistent with the affin

  13. The insecticidal activity and action mode of an imidacloprid analogue, 1-(3-pyridylmethyl)-2-nitroimino-imidazolidine.

    PubMed

    Zhuang, An-Xiang; Zhang, Yi-Xi; Zhang, Hui; Liu, Ze-Wen

    2016-10-01

    Neonicotinoids, such as imidacloprid, are key insecticides extensively used for control of Nilaparvata lugens. However, imidacloprid resistance has been reported in many Asian countries in recent years. To understand the roles of the chlorine atom of pyridyl group on insecticidal activity and resistance, the atom was removed to generate an imidacloprid analogue DC-Imi (DesChlorine Imidacloprid). DC-Imi showed significantly higher toxicity than imidacloprid in the susceptible strain of N. lugens, but had medium level cross-resistance in an imidacloprid-resistant strain. In Xenopus oocyte expressed nicotinic acetylcholine receptors (nAChRs) Nlα1/rβ2, the inward currents evoked by DC-Imi were detected and could be blocked by typical nAChRs antagonist dihydro-β-erythroidine (DHβE), which demonstrated that DC-Imi acted as an agonist on insect nAChRs. The efficacy of DC-Imi on Nlα1/rβ2 was 1.8-fold higher than that of imidacloprid. In addition, the influence of an imidacloprid resistance associated mutation (Y151S) on agonist potencies was evaluated. Compared with the wild-type receptor, the mutation reduced maximal inward current of DC-Imi to 55.6% and increased half maximal effective concentration (EC50 ) to 3.53-fold. Compared with imidacloprid (increasing EC50 to 2.38-fold of wild-type receptor), Y151S mutation decreased DC-Imi potency more significantly. The results indicated that the selective and possibly high toxicities could be achieved through the modification of 6-chloro-3-pyridyl group in imidacloprid and other neonicotinoids.

  14. Evaluation of Cancer Preventive Activity and Structure-Activity Relationships of 3-Demethylubiquinone Q2, Isolated from the Ascidian Aplidium glabrum, and its Synthetic Analogues

    PubMed Central

    Fedorov, Sergey N.; Radchenko, Oleg S.; Shubina, Larisa K.; Balaneva, Nadezhda N.; Bode, Ann M.; Stonik, Valentin A.; Dong, Zigang

    2006-01-01

    Purpose 3-Demethylubiquinone Q2 (1) was isolated from the ascidian Aplidium glabrum. The cancer preventive properties and the structure-activity relationship for 3-demethylubiquinone Q2 (1) and 12 of its synthetic analogues (3–14) are reported. Methods Compounds 3–14, having one or several di- or triprenyl substitutions and quinone moieties with methoxyls in different positions, were synthesized. The cancer preventive properties of compounds 1 and 3–14 were tested in JB6 Cl41 mouse skin cells, using a variety of assessments, including the MTS assay, flow cytometry, and soft agar assay. Statistical nonparametric methods were used to confirm statistical significance. Results All quinones tested were shown to inhibit JB6 Cl41 cell transformation, to induce apoptosis, AP-1 and NF-κB activity, and to inhibit p53 activity. The most promising effects were indicated for compounds containing two isoprene units in a side chain and a methoxyl group at the para-position to a polyprenyl substitution. Conclusions Quinones 1 and 3–14 demonstrated cancer preventive activity in JB6 Cl41 cells, which may be attributed to the induction of p53-independent apoptosis. These activities depended on the length of side chains and on the positions of the methoxyl groups in the quinone part of the molecule. PMID:16320003

  15. Analogies between respiration and a light-driven proton pump as sources of energy for active glutamate transport in Halobacterium halobium

    NASA Technical Reports Server (NTRS)

    Belliveau, J. W.; Lanyi, J. K.

    1977-01-01

    Halobacterium halobium is known to contain sheets of bacteriorhodopsin, a pigment which upon exposure to light undergoes cyclic protonation and deprotonation, resulting in net H(+) translocation. In this paper, experiments were conducted to test H. halobium cell envelope vesicles for respiration-induced glutamate uptake. It is shown that glutamate transport in H. halobium cell envelope vesicles can occur as a result of respiration, as well as light acting on bacteriorhodopsin. Glutamate transport can be energized by the oxidation of dimethyl phenylenediamine, and the properties of the transport system are entirely analogous to those observed with illumination as the source of energy. In the case of respiration-dependent glutamate transport, the transportation is also driven by a Na(+) gradient, thereby confirming the existence of a single glutamate transport system independent of the source of energy. The analogy observed is indirect evidence that the cytochrome oxidase of H. halobium functions as a H(+) pump.

  16. Characterization of glutamate decarboxylase from Lactobacillus plantarum and its C-terminal function for the pH dependence of activity.

    PubMed

    Shin, Sun-Mi; Kim, Hana; Joo, Yunhye; Lee, Sang-Jae; Lee, Yong-Jik; Lee, Sang Jun; Lee, Dong-Woo

    2014-12-17

    The gadB gene encoding glutamate decarboxylase (GAD) from Lactobacillus plantarum was cloned and expressed in Escherichia coli. The recombinant enzyme exhibited maximal activity at 40 °C and pH 5.0. The 3D model structure of L. plantarum GAD proposed that its C-terminal region (Ile454-Thr468) may play an important role in the pH dependence of catalysis. Accordingly, C-terminally truncated (Δ3 and Δ11 residues) mutants were generated and their enzyme activities compared with that of the wild-type enzyme at different pH values. Unlike the wild-type GAD, the mutants showed pronounced catalytic activity in a broad pH range of 4.0-8.0, suggesting that the C-terminal region is involved in the pH dependence of GAD activity. Therefore, this study may provide effective target regions for engineering pH dependence of GAD activity, thereby meeting industrial demands for the production of γ-aminobutyrate in a broad range of pH values.

  17. Chronic SO2 inhalation above environmental standard impairs neuronal behavior and represses glutamate receptor gene expression and memory-related kinase activation via neuroinflammation in rats.

    PubMed

    Yao, Gaoyi; Yue, Huifeng; Yun, Yang; Sang, Nan

    2015-02-01

    Sulfur dioxide (SO2), as a ubiquitous air pollutant implicated in the genesis of pulmonary disease, is now being considered to be involved in neurotoxicity and increased risk for hospitalization of brain disorders. However, comparatively little is known about the impact of chronically SO2 inhalation on neuronal function. In the present study, by exposing male Wistar rats to SO2 at 3.50 and 7.00 mg/m(3) (approximately 1225 and 2450 ppb, 4.08-8.16 (24h average concentration) times higher than the EPA standard for environmental air concentrations) or filtered air for 90 days, we investigated the impact of chronic SO2 inhalation on performance in Morris water maze, and probed the accompanying neurobiological effects, including activity-regulated cytoskeletal associated gene (Arc) and glutamate receptor gene expression, memory-related kinase level and inflammatory cytokine release in the hippocampus. Here, we found that SO2 exposure reduced the number of target zone crossings and time spent in the target quadrant during the test session in the spatial memory retention of the Morris water maze. Following the neuro-functional abnormality, we detected that SO2 inhalation reduced the expression of Arc and glutamate receptor subunits (GluR1, GluR2, NR1, NR2A, and NR2B) with a concentration-dependent property in comparison to controls. Additionally, the expression of memory kinases was attenuated statistically in the animals receiving the higher concentration, including protein kinase A (PKA), protein kinase C (PKC) and calcium/calmodulin-dependent protein kinaseIIα (CaMKIIα). And the inflammatory cytokine release was increased in rats exposed to SO2. Taken together, our results suggest that long-term exposure to SO2 air pollution at concentrations above the environmental standard in rats impaired spatial learning and memory, and indicate a close link between the neurobiological changes highlighted in the brain and the behavioral disturbances.

  18. Analysis of a soluble calmodulin binding protein from fava bean roots: identification of glutamate decarboxylase as a calmodulin-activated enzyme.

    PubMed

    Ling, V; Snedden, W A; Shelp, B J; Assmann, S M

    1994-08-01

    The identity of a soluble 62-kD Ca(2+)-dependent calmodulin binding protein (CaM-BP) from fava bean seedlings was determined. Using 125I-CaM overlay assays, a class of soluble CaM-BPs was detected in extracts of tissues comprising the axis of 1.5-week-old seedlings, excluding the root tip and emergent leaves. The size of these CaM-BPs was not uniform within all parts of the plant; the apparent molecular masses were 62 kD in roots, 60 kD in stems, and 64 kD in nodules. The root 62-kD CaM-BP was purified, and internal microsequence analysis was performed on the protein. A tryptic peptide derived from the CaM-BP consisted of a 13-residue sequence corresponding to a highly conserved region of glutamate decarboxylase (GAD), an enzyme that catalyzes the alpha-decarboxylation of glutamate to form the stress-related metabolite gamma-aminobutyrate. Activity