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Kazuya Douki, Hiroyuki Ono, Tohru Taniguchi, Jun Shimokawa, Masato Kitamura, Tohru Fukuyama
Optically pure hinckdentine A was synthesized on a 300 mg scale via an asymmetric catalysis-based strategy. The key steps to the first asymmetric synthesis involved i) enantioselective dearomative cyclization of an achiral N-acyl indole that allowed for the efficient construction of the key polycyclic indoline intermediate with a crucial tetrasubstituted stereogenic carbon center, ii) Beckmann fragmentation-mediated ring expansion, iii) rearrangement-based introduction of an anilinic nitrogen atom, iv) regioselective tribromination, and v) final closure of the cyclic amidine moiety...
October 22, 2016: Journal of the American Chemical Society
D Sivaramakrishna, Musti J Swamy
N-Acyl-β-alanines (NABAs) are structural homologues of N-acylglycines (NAGs) and N-acyl-γ-aminobutyric acids (NAGABAs), and achiral isomers of N-acylalanines, which are all present in mammalian brain and other tissues and modulate activity of biological receptors with various functions. In the present study, we synthesized and characterized a homologous series of NABAs bearing saturated acyl chains (n=8-20) and investigated their supramolecular organization and thermotropic phase behavior. In differential scanning calorimetric (DSC) studies, most of the NABAs gave one or two minor transitions before the main chain-melting phase transition in the dry state as well as upon hydration with water, but gave only a single transition when hydrated with buffer (pH7...
October 19, 2016: Chemistry and Physics of Lipids
Yuka Nakaya, Mayu Takaya, Yuta Hinatsu, Tammam Alama, Kosuke Kusamori, Hidemasa Katsumi, Toshiyasu Sakane, Akira Yamamoto
Bisphosphonates (BPs) are carbon-substituted pyrophosphate analogs that exhibit a high affinity to hydroxyapatite and specifically inhibit bone resorption. Alendronate sodium (sodium 4-amino-1-hydroxybutylidene-1,1-bisphosphonate trihydrate) is a typical BP compound in clinical use. BPs have very low bioavailability, typically <1% after their oral administration, and their intestinal absorption is further reduced by co-administered drugs or food. In this study, we examined the effects of N-acyl amino acids and N-acyl taurates on the small intestinal absorption of alendronate...
October 19, 2016: Journal of Pharmaceutical Sciences
Claire M Young, Daniel G Stark, Thomas H West, James E Taylor, Andrew D Smith
N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the "imidazolium" effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes...
October 20, 2016: Angewandte Chemie
Feifei Cheng, Anzhou Ma, Guoqiang Zhuang, Rupert G Fray
In order to cope with pathogens, plants have evolved sophisticated mechanisms to sense pathogenic attacks and to induce defence responses. The N-acyl-homoserine lactone (AHL)-mediated quorum sensing in bacteria regulates diverse physiological processes including those involved in pathogenicity. In this work, we study the interactions between AHL-producing transgenic tobacco plants and Pseudomonas syringae pv. tabaci 11528 (P. syringae 11528). Both a reduced incidence of disease and decrease in the growth of P...
October 18, 2016: Molecular Plant Pathology
Andrew G Palmer, Arijit Mukherjee, Danielle M Stacy, Stephen Lazar, Jean-Michel Ané, Helen E Blackwell
Density-dependent phenotypic switching in bacteria, the phenomenon of quorum sensing (QS), is instrumental in many pathogenic and mutualistic behaviors. In many Gram-negative bacteria, QS is regulated by N-acylated-l-homoserine lactones (AHLs). Synthetic analogues of these AHLs hold significant promise for regulating QS at the host-symbiont interface. Regulation depends on refined temporal and spatial models of quorums under native conditions. Critical to this is an understanding of how the presence of these signals may affect a prospective host...
October 14, 2016: Chembiochem: a European Journal of Chemical Biology
F G Dupuy, S P Fernández Bordín, B Maggio, R G Oliveira
Ceramides constitute a group of lipids with usually high melting temperature that also favor negative curvature in membranes when mixed with other lipids. The short chain C10:0 ceramide is an asymmetric lipid which consists of an 18 carbon sphingosine base N-acylated with decanoic acid. According to high sensitivity differential scanning calorimetry, it shows a minor exothermic peak at 61°C and a main endothermic transition at 75°C. By small angle X-ray scattering and polarized light microscopy we found that, at temperatures below the main transition, the fully hydrated lipid dispersions are arranged in a tridimensional structure corresponding to an inverted hexagonal phase...
October 5, 2016: Colloids and Surfaces. B, Biointerfaces
Tomoko Abe, Yoshiteru Hashimoto, Sayaka Sugimoto, Kenta Kobayashi, Takuto Kumano, Michihiko Kobayashi
The adenylation domain of nonribosomal peptide synthetase (NRPS) is responsible for the selective substrate recognition and its activation (as an acyl-O-AMP intermediate) during ATP consumption. DhbE, a stand-alone adenylation domain, acts on an aromatic acid, 2,3-dihydroxybenzoic acid (DHB). This activation is the initial step of the synthesis of bacillibactin that is a high-affinity small-molecule iron chelator also termed siderophore. Subsequently, the activated DHB is transferred and attached covalently to a peptidyl carrier protein domain via a thioester bond...
October 12, 2016: Journal of Antibiotics
Niharika Singh, Amrita Patil, Asmita Prabhune, Mamta Raghav, Gunjan Goel
The present study investigates the role of quorum sensing (QS) molecules expressed by C. sakazakii in biofilm formation and extracellular polysaccharide expression. The QS signaling was detected using Chromobacterium violaceum 026 and Agrobacterium tumefaciens NTL4(pZLR4) based bioassay. Long chain N-acyl-homoserine lactones (AHLs) with C6- C18 chain length were identified using High Performance Liquid Chromatography and Liquid Chromatography-High Resolution Mass Spectrometry. A higher Specific Biofilm Formation (SBF) index (p < 0...
October 7, 2016: Virulence
Dominika Załubiniak, Maciej Zakrzewski, Piotr Piątek
Compounds 2 and 3 were designed and prepared as heteroditopic ion-pair receptors. The design features a 2,2-bis(aminomethyl)propionic acid core to connect and pre-organize binding groups. The cation binding is provided by a sodium selective N-acyl aza-18-crown-6 subunit whereas for anion complexation, two urea groups (receptor 2) or two squaramide groups (receptor 3) were introduced. Beyond acting as anion binding sites, the urea and squaramide groups were used to support sodium cation complexation through metal carbonyl oxygen lone pair interactions...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Nishaben M Patel, Joseph D Moore, Helen E Blackwell, Daniel Amador-Noguez
N-acyl L-homoserine lactones (AHLs) constitute a predominant class of quorum-sensing signaling molecules used by Gram-negative bacteria. Here, we report a sensitive and non-targeted HPLC-MS/MS method based on parallel reaction monitoring (PRM) to identify and quantitate known, unanticipated, and novel AHLs in microbial samples. Using a hybrid quadrupole-high resolution mass analyzer, this method integrates MS scans and all-ion fragmentation MS/MS scans to allow simultaneous detection of AHL parent-ion masses and generation of full mass spectra at high resolution and high mass accuracy in a single chromatographic run...
2016: PloS One
Diego Romano Perinelli, Marco Cespi, Luca Casettari, Driton Vllasaliu, Michela Cangiotti, Maria Francesca Ottaviani, Gianfabio Giorgioni, Giulia Bonacucina, Giovanni Filippo Palmieri
Toxicity is one of the main concern limiting the use of surfactants. Many efforts have been devoted to the development of new amphiphilic molecules characterized by a lower toxicological profile and environmental impact. N-acyl amino acids are a class of anionic surfactants that can find applications in different technological fields as an alternative to sulphate-based surfactants (e.g., sodium dodecyl sulphate). The understanding of the relationship between chemical structure and toxicological profile is fundamental for the disclosure of the full potential of these amphiphiles...
September 28, 2016: European Journal of Pharmaceutics and Biopharmaceutics
Sigde Mamani, Danielle Moinier, Yann Denis, Laurent Soulère, Yves Queneau, Emmanuel Talla, Violaine Bonnefoy, Nicolas Guiliani
While a functional quorum sensing system has been identified in the acidophilic chemolithoautotrophic Acidithiobacillus ferrooxidans ATCC 23270(T) and shown to modulate cell adhesion to solid substrates, nothing is known about the genes it regulates. To address the question of how quorum sensing controls biofilm formation in A. ferrooxidans (T), the transcriptome of this organism in conditions in which quorum sensing response is stimulated by a synthetic superagonist AHL (N-acyl homoserine lactones) analog has been studied...
2016: Frontiers in Microbiology
Yakov M Koen, Ke Liu, Heather Shinogle, Todd D Williams, Robert P Hanzlik
The hepatotoxicity of acetaminophen (APAP) is generally attributed to the formation of a reactive quinoneimine metabolite (NAPQI) that depletes glutathione and covalently binds to hepatocellular proteins. To explore the importance of the N-acyl group in APAP metabolism and toxicity, we synthesized 12 acyl side chain homologues of acetaminophen (APAP) and its 3'-regioisomer (AMAP), including the respective N-(4-pentynoyl) analogues PYPAP and PYMAP. Rat hepatocytes converted APAP, AMAP, PYPAP, and PYMAP extensively to O-glucuronide and O-sulfate conjugates in varying proportions, whereas glutathione or cysteine conjugates were observed only for APAP and PYPAP...
October 13, 2016: Chemical Research in Toxicology
Ben D Tall, Hannah R Chase, Gopal R Gopinath
No abstract text is available yet for this article.
September 27, 2016: Virulence
Géraldine San Jose, Emily R Jackson, Amanda Haymond, Chinchu Johny, Rachel L Edwards, Xu Wang, R Carl Brothers, Emma K Edelstein, Audrey R Odom, Helena I Boshoff, Robin D Couch, Cynthia S Dowd
Despite continued research efforts, the threat of drug resistance from a variety of bacteria continues to plague clinical communities. Discovery and validation of novel biochemical targets will facilitate development of new drugs to combat these organisms. The methylerythritol phosphate (MEP) pathway to make isoprene units is a biosynthetic pathway essential to many bacteria. We and others have explored inhibitors of the MEP pathway as novel antibacterial agents. Mycobacterium tuberculosis, the causative agent of tuberculosis, and Yersinia pestis, resulting in the plague or "black death", both rely on the MEP pathway for isoprene production...
October 12, 2016: ACS Infectious Diseases
Gregg M Schwarzwalder, David R Scott, Christopher D Vanderwal
A concise and stereoselective synthesis of exiguaquinol dessulfate is described. Sequential application of a Diels-Alder cycloaddition, a desymmetrizing aldol addition, and a reductive Heck cyclization established most of the architecture of exiguaquinol, and a carefully choreographed introduction of the polar substituents afforded the title compound; unfortunately, naphthoquinol sulfation could not be achieved to deliver exiguaquinol. Our hypothesis regarding the configurational preference of the N-acyl hemiaminal, which was based upon an analysis of internal hydrogen-bonding interactions with polar functional groups, was proven correct...
September 27, 2016: Chemistry: a European Journal
Francisco Javier Pavón, Eva María Marco, Mariam Vázquez, Laura Sánchez, Patricia Rivera, Ana Gavito, Virginia Mela, Francisco Alén, Juan Decara, Juan Suárez, Elena Giné, José Antonio López-Moreno, Julie Chowen, Fernando Rodríguez-de-Fonseca, Antonia Serrano, María Paz Viveros
Intermittent alcohol exposure is a common pattern of alcohol consumption among adolescents and alcohol is known to modulate the expression of the endocannabinoid system (ECS), which is involved in metabolism and inflammation. However, it is unknown whether this pattern may have short-term consequences on the ECS in the spleen. To address this question, we examined the plasma concentrations of metabolic and inflammatory signals and the splenic ECS in early adult rats exposed to alcohol during adolescence. A 4-day drinking in the dark (DID) procedure for 4 weeks was used as a model of intermittent forced-alcohol administration (20%, v/v) in female and male Wistar rats, which were sacrificed 2 weeks after the last DID session...
2016: PloS One
James John, Rajagopalan Saranathan, Lakshmi Narayana Adigopula, Vasanth Thamodharan, Satya Prakash Singh, T Pragna Lakshmi, Mallu Abhiram CharanTej, R Srinivasa Rao, R Krishna, H Surya Prakash Rao, K Prashanth
Secretory N-acyl homoserine lactones (AHLs) mediate quorum sensing (QS) in bacteria. AHLs are shown to be inhibitory for an unrelated group of bacteria and might mimic host signalling elements, thereby subverting the regulatory events in host cells. This study investigated the AHL produced by Acinetobacter baumannii and analysed its effect on other bacterial species and mammalian cells. Chemically characterized AHL had an m/z value of 325 with a molecular formula C18H31NO4 and showed its inhibitory potential against Staphylococcus aureus...
October 2016: Biofouling
Jevgenijs Tjutrins, Rajiv Dhawan, Yingdong Lu, Bruce A Arndtsen
The palladium-catalyzed carbonylative coupling of imines, acid chlorides, and dipolarophiles can provide efficient routes to prepare nitrogen-containing heterocycles. One challenge in developing this reaction, and in the creation of more active catalyst systems, is the lack of data on how this complex transformation proceeds. To address this, we report here the results of our mechanistic studies on this system, and in particular the formation of mesoionic münchnones. This includes the synthesis of key catalytic intermediates, model reactions, and kinetic studies that support the role of these compounds in catalysis...
September 19, 2016: Chemistry: a European Journal
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