- Silver comes into play: Henry reaction and domino cycloisomerisation sequence catalysed by [Ag(i)(Pc-L)] complexes
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We report herein the synthesis of new pyridine-containing macrocyclic ligands (Pc-L) bearing a non-innocent pendant arm, by exploiting both chiral and functional properties of natural amino acids. The obtained macrocyclic ligands were employed to synthesize well-defined cationic silver(i) complexes that were shown to be competent catalysts for the Henry (nitroaldol) reaction. Good to excellent yields and full selectivity in the β-nitroalcohol product were obtained starting from electron-poor aromatic aldehydes or other activated aldehydes such as furfural under mild reaction conditions. The straightforward synthesis of the macrocyclic ligands starting from cheap commercially available starting materials allowed the introduction of a suitable basic functionality into the ligand pendant arm, thus providing a bifunctional catalyst. Based on our previous experience in the [Ag(i)(Pc-L)] catalysed domino addition/cycloisomerisation reaction of o-alkynylbenzaldehydes and nucleophiles, the synthesis of isochromenes coupling the Henry reaction and the cycloisomerisation in a single step was subsequently explored. Although with low selectivity, [Ag(i)(Pc-L)] cationic complexes were able to promote such a cascade reaction and a possible mechanism based on experimental evidence has been proposed.
- Tseberlidis, Giorgio,Dell'Acqua, Monica,Valcarenghi, Daniele,Gallo, Emma,Rossi, Elisabetta,Abbiati, Giorgio,Caselli, Alessandro
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p. 97404 - 97419
(2016/10/25)
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- Cationic surfactants derived from lysine: Effects of their structure and charge type on antimicrobial and hemolytic activities
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Three different sets of cationic surfactants from lysine have been synthesized. The first group consists of three monocatenary surfactants with one lysine as the cationic polar head with one cationic charge. The second consists of three monocatenary surfactants with two amino acids as cationic polar head with two positive charges. Finally, four gemini surfactants were synthesized in which the spacer chain and the number and type of cationic charges have been regulated. The micellization process, antimicrobial activity, and hemolytic activity were evaluated. The critical micelle concentration was dependent only on the hydrophobic character of the molecules. Nevertheless, the antimicrobial and hemolytic activities were related to the structure of the compounds as well as the type of cationic charges. The most active surfactants against the bacteria were those with a cationic charge on the trimethylated amino group, whereas all of these surfactants showed low hemolytic character.
- Colomer,Pinazo,Manresa,Vinardell,Mitjans,Infante,Pérez
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experimental part
p. 989 - 1002
(2011/04/24)
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- Nε-Modified lysine containing inhibitors for SIRT1 and SIRT2
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Sirtuins catalyze the NAD+ dependent deacetylation of N ε-acetyl lysine residues to nicotinamide, O′-acetyl-ADP- ribose (OAADPR) and Nε-deacetylated lysine. Here, an easy-to-synthesize Ac-Ala-Lys-Ala sequence has been used as a probe for the screening of novel Nε-modified lysine containing inhibitors against SIRT1 and SIRT2. Nε-Selenoacetyl and N ε-isothiovaleryl were the most potent moieties found in this study, comparable to the widely studied Nε-thioacetyl group. The Nε-3,3-dimethylacryl and Nε-isovaleryl moieties gave significant inhibition in comparison to the Nε-acetyl group present in the substrates. In addition, the studied Nε- alkanoyl, Nε-α,β-unsaturated carbonyl and N ε-aroyl moieties showed that the acetyl binding pocket can accept rather large groups, but is sensitive to even small changes in electronic and steric properties of the Nε-modification. These results are applicable for further screening of Nε-acetyl analogues.
- Huhtiniemi, Tero,Suuronen, Tiina,Lahtela-Kakkonen, Maija,Bruijn, Tanja,J??skel?inen, Sanna,Poso, Antti,Salminen, Antero,Lepp?nen, Jukka,Jarho, Elina
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supporting information; experimental part
p. 5616 - 5625
(2010/09/14)
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- Cationic surfactants from lysine: Synthesis, micellization and biological evaluation
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Biocompatible cationic surfactants from the amino acid lysine (hydrochloride salts of Nε-lauroyl lysine methyl ester, Nε-myristoyl lysine methyl ester and Nε-palmitoyl lysine methyl ester) have been prepared in high yields
- Perez, Lourdes,Pinazo, Aurora,Teresa Garcia,Lozano, Marina,Manresa, Angeles,Angelet, Marta,Pilar Vinardell,Mitjans, Montse,Pons, Ramon,Rosa Infante
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experimental part
p. 1884 - 1892
(2009/10/02)
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- Time-dependence and preliminary SAR studies in inhibition of nitric oxide synthase isoforms by homologues of thiocitrulline
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Treatment of Nα-Cbz-Nε -(2-hydroxyethylaminothiocarbonyl)-L-lysine N-(2-hydroxyethyl)amide with boiling hydrochloric acid gave Nε -(4,5-dihydrothiazol-2-yl)-L-lysine. This was a weak and non-isoform selective inhibitor of NOS, whereas Nε -aminothiocarbonyl-L-lysine and its methyl ester were potent, with IC 50=13 and 18 μM, respectively, against human iNOS and IC 50=3 and 8 μM, respectively, against rat nNOS. Time dependence was observed for inhibition of nNOS by the ester.
- Goodyer, Claire L. M.,Chinje, Edwin C.,Jaffar, Mohammed,Stratford, Ian J.,Threadgill, Michael D.
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p. 3679 - 3680
(2007/10/03)
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- A New Method for the Synthesis of Nε-Acetyl-Nε-hydroxy-L-lysine, the Iron-Binding Constituent of Several Important Siderophores
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Oxidation of the ε-amino group of Nα-(carbobenzyloxy)-L-lysine methyl ester with dimethyldioxirane in acetone gave the acetone-derived nitrone of the desired hydroxylamine.Acidic hydrolysis, acetylation, and subsequent deprotection provided a s
- Hu, Jingdan,Miller, Marvin J.
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p. 4858 - 4861
(2007/10/02)
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- Peptide Synthesis by Means of Immobilized Enzymes II. Immobilized Trypsin, Thermolysin and Papain
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Model studies were performed on the utility of covalently immobilized trypsin, thermolysin and papain for peptide bond formation.Trypsin and thermolysin catalyzed the formation of peptide bonds with nearly the same efficiency as the soluble proteases and they could be re-used successfully for further coupling experiments.The possibility of using immobilized trypsin and papain for kinetically controlled peptide bond formation was investigated.With the serine type enzyme trypsin excellent product yields were obtained starting with ester carboxyl components and an economical ratio of substrates.Experiments with the thiol protease papain were unsatisfactory because the once formed product is hydrolyzed as fact as the starting ester substrate used. - Keywords: Immobilized enzymes; Papain; Peptide synthesis; Thermolysin; Trypsin
- Koennecke, Andreas,Haensler, Marion,Schellenberger, Volker,Jakubke, Hans-Dieter
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p. 433 - 444
(2007/10/02)
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