51883-36-4Relevant articles and documents
Structure of the unusual Sinorhizobium fredii HH103 lipopolysaccharide and its role in symbiosis
Di Lorenzo, Flaviana,Speciale, Immacolata,Silipo, Alba,Alías-Villegas, Cynthia,Acosta-Jurado, Sebastián,Rodríguez-Carvajal, Miguel-ángel,Dardanelli, Marta S.,Palmigiano, Angelo,Garozzo, Domenico,Ruiz-Sainz, José-Enrique,Molinaro, Antonio,Vinardell, José-María
, p. 10969 - 10987 (2021/01/07)
Rhizobia are soil bacteria that form important symbiotic associations with legumes, and rhizobial surface polysaccharides, such as K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS), might be important for symbiosis. Previously, we obtained a mutant of Sinorhizobium fredii HH103, rkpA, that does not produce KPS, a homopolysaccharide of a pseudaminic acid derivative, but whose LPS electrophoretic profile was indistinguishable from that of the WT strain. We also previously demonstrated that the HH103 rkpLMNOPQ operon is responsible for 5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-L-glyc-ero-L-manno-nonulosonic acid [Pse5NAc7(3OHBu)] production and is involved in HH103 KPS and LPS biosynthesis and that an HH103 rkpM mutant cannot produce KPS and displays an altered LPS structure. Here, we analyzed the LPS structure of HH103 rkpA, focusing on the carbohydrate portion, and found that it contains a highly heterogeneous lipid A and a peculiar core oligosaccharide composed of an unusually high number of hexuronic acids containing b-configured Pse5NAc7(3OHBu). This pseudaminic acid derivative, in its a-configuration, was the only structural component of the S. fredii HH103 KPS and, to the best of our knowledge, has never been reported from any other rhizobial LPS. We also show that Pse5NAc7(3OHBu) is the complete or partial epitope for a mAb, NB6-228.22, that can recognize the HH103 LPS, but not those of most of the S. fredii strains tested here. We also show that the LPS from HH103 rkpM is identical to that of HH103 rkpA but devoid of any Pse5NAc7(3OHBu) residues. Notably, this rkpM mutant was severely impaired in symbiosis with its host, Macroptilium atropurpureum.
Chemical synthesis of burkholderia lipid a modified with glycosyl phosphodiester-linked 4-amino-4-deoxy-β-L-arabinose and its immunomodulatory potential
Hollaus, Ralph,Ittig, Simon,Hofinger, Andreas,Haegman, Mira,Beyaert, Rudi,Kosma, Paul,Zamyatina, Alla
supporting information, p. 4102 - 4114 (2015/10/19)
Modification of the Lipid A phosphates by positively charged appendages is a part of the survival strategy of numerous opportunistic Gram-negative bacteria. The phosphate groups of the cystic fibrosis adapted Burkholderia Lipid A are abundantly esterified by 4-amino-4-deoxy-b-larabinose (β-L-Ara4N), which imposes resistance to antibiotic treatment and contributes to bacterial virulence. To establish structural features accounting for the unique pro-inflammatory activity of Burkholderia LPS we have synthesised Lipid A substituted by β-L-Ara4N at the anomeric phosphate and its Ara4N-free counterpart. The double glycosyl phosphodiester was assembled by triazolyl-tris-(pyrrolidinyl)phosphonium-assisted coupling of the β-L-Ara4N H-phosphonate to α-lactol of β(1→6) diglucosamine, pentaacylated with (R)-(3)-acyloxyacyl-and Alloc-protected (R)-(3)-hydroxyacyl residues. The intermediate 1,1'-glycosyl-H-phosphonate diester was oxidised in anhydrous conditions to provide, after total deprotection, β-L-Ara4N-substituted Burkholderia Lipid A. The β-L-Ara4N modification significantly enhanced the pro-inflammatory innate immune signaling of otherwise non-endotoxic Burkholderia Lipid A.
Asymmetric reduction of monoketo hexadecanoic acid methyl esters
Türker, Gülen,Yusufoglu, Ayse
, p. 1531 - 1535 (2013/06/26)
Methyl 2-,3-,6-,8-,14- and 15-keto hexadecanoates were reduced by using NaBH4 in presence of 1,2;5,6-di-O-isopropilydene-Dglucofuranose [DIPGH], R(+)-1,1′-binaphthyl-2,2′-diol [RBND] and pivalic acid [PA]. The reduction of 2- and 3-keto esters in the presence of (+)-1,1′-binaphthyl-2,2′-diol results in considerably higher stereoselectivities (95 % ee). Enantiometric excess (ee %) was determined by 1H and 13C NMR analyses using a shift reagent, Eu(tfc)3. Copyright
Termination of the structural confusion between plipastatin A1 and fengycin IX
Honma, Miho,Tanaka, Kazuaki,Konno, Katsuhiro,Tsuge, Kenji,Okuno, Toshikatsu,Hashimoto, Masaru
experimental part, p. 3793 - 3798 (2012/08/28)
Plipastatin A1 and fengycin IX were experimentally proven to be identical compounds, while these had been considered as diastereomers due to the permutation of the enantiomeric pair of Tyr in most papers. The 1H NMR spectrum changed to become quite similar to that of plipastatin A1, when the sample which provided resembled spectrum of fengycin IX was treated with KOAc followed by LH-20 gel filtration. Our structural investigations disclosed that the structures of these molecules should be settled into that of plipastatin A1 by Umezawa (l-Tyr4 and d-Tyr10).
Asymmetric synthesis of long chain β-hydroxy fatty acid methyl esters as new elastase inhibitors
Hasdemir, Belma,Onar, Huelya Elik,Yusufolu, Aye
, p. 1100 - 1105 (2012/11/07)
Herein, β-hydroxy methyl esters with an even carbon chain length of 12-20 1b-5b were synthesized by three different asymmetric reduction methods I, II III from their corresponding β-keto methyl esters 1a-5a with the aim of determining their elastase activities. In method I, chiral catalyst A was prepared from chiral ligand (R)-binaphthol 1, while in method II, chiral catalyst B was synthesized from (2R,3R)-diisopropyl tartrate 2. Chiral catalyst B has not previously been used in asymmetric borane reductions or in the asymmetric synthesis of chiral β-hydroxy methyl esters. In method III, an asymmetric reduction was catalysed by (R)-Me-CBS oxazaborolidine 3. Hydride transfer was carried out in all of these methods by BH3· SMe2. Chiral hydroxy methyl esters with an (S)-configuration were synthesized by method I and with an (R)-configuration via methods II and III. The chiral hydroxy methyl esters obtained were analysed by chiral HPLC for their ee % values. Methods I, II and III were applied to long chain β-keto methyl esters for the first time. The reduction methods I, II and III were examined in terms of reaction yield and enantiomeric excess according to carbon chain length and the variable ratio of chiral catalysts to β-keto methyl ester. The highest enantiomeric excess of 90% ee was found in method III for 12 and 14 carbon numbers.
BETA-LACTONE COMPOUNDS
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Page/Page column 11-12, (2009/05/28)
The present invention provides compounds having the general structure A, or a pharmaceutically acceptable derivatives thereof: wherein R is an alkyl group, and R1 comprises at least one moiety selected from a group consisting of an alkyl, an alkenyl, an aryl, a heterocycle, hydroxyl, ester, amido, aldehyde, and a halogen.
Non-volatile floral oils of Diascia spp. (Scrophulariaceae)
Dumri, Kanchana,Seipold, Lars,Schmidt, Juergen,Gerlach, Guenter,Doetterl, Stefan,Ellis, Allan G.,Wessjohann, Ludger A.
, p. 1372 - 1383 (2008/09/20)
The floral oils of Diascia purpurea, Diascia vigilis, Diascia cordata, Diascia megathura, Diascia integerrima and Diascia barberae (Scrophulariaceae) were selectively collected from trichome elaiophores. The derivatized floral oils were analyzed by gas chromatography-mass spectrometry (GC-MS), whilst the underivatized samples were analysed by electrospray ionization mass spectrometry (ESI-MS) and Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS). The most common constituents of the floral oils investigated are partially acetylated acylglycerols of (3R)-acetoxy fatty acids (C14, C16, and C18), as was proven with non-racemic synthetic reference samples. The importance of these oils for Rediviva bees is discussed in a co-evolutionary context.
General enantioselective synthesis of butyrolactone natural products via ruthenium-SYNPHOS-catalyzed hydrogenation reactions
Blanc, Delphine,Madec, Jonathan,Popowyck, Florence,Ayad, Tahar,Phansavath, Phannarath,Ratovelomanana-Vidal, Virginie,Genet, Jean-Pierre
, p. 943 - 950 (2008/03/27)
Enantioselective syntheses of several paraconic acids have been achieved using catalyzed asymmetric hydrogenation of β-keto esters with SYNPHOS as a ligand. This strategy allowed the short synthesis of biologically active (-)-methylenolactocin 1, (-)-protolichesterinic acid 2, (-)-phaseolinic acid 3 and (+)-roccellaric acid 4.
Enantioselective Hydrogenation of β-Keto Esters using Chiral Diphosphine-Ruthenium Complexes: Optimization for Academic and Industrial Purposes and Synthetic Applications
Ratovelomanana-Vidal,Girard,Touati,Tranchier,Ben Hassine,Genet
, p. 261 - 274 (2007/10/03)
Enantioselective hydrogenation using chiral complexes between atropisomeric diphosphines and ruthenium is a powerful tool for producing chiral compounds. Using a simple and straightforward in situ catalyst preparation, the conditions were optimized using molecular hydrogen for both academic and industrial purposes. This led to the best conditions and the lowest catalytic ratio required for the pressure used. Hydrogenation of various β-keto esters was efficiently performed at atmospheric and higher pressures, leading to the use of very low catalyst-substrate ratios up to 1/20,000. Asymmetric hydrogenations were used in key-steps towards the total synthesis of corynomycolic acid, Duloxetine and Fluoxetine.
