Search results for "amines"
showing 10 items of 664 documents
Peroxodisulfate as a chemical initiator for methacrylate-ester monolithic columns for capillary electrochromatography
2008
Organic monolithic stationary phases for CEC were synthesized in situ in fused-silica capillaries. Polymerization mixtures were composed of butyl methacrylate, ethylene dimethacrylate, and [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride in the presence of a porogenic solvent, using ammonium peroxodisulfate as chemical initiator, and N,N,N',N'-tetramethylethylenediamine to activate the reaction. The influence of the amount of initiator, temperature, and composition of porogenic solvent on the physical and chromatographic properties of monolithic stationary phases has been investigated. A minimum plate height of 14.5 microm was obtained at 18 wt% of 1,4-butanediol in the polymerization …
Reversible coordination of dioxygen by tripodal tetraamine copper complexes incorporated in a porous silica framework.
2010
The present study reports the synthesis and rational design of porous structured materials by using a templating method. A tetraethoxysilylated tripodal tetraamine (TREN) was covalently incorporated in a silica framework with a double imprint: A surfactant template and a metal ion imprint. The presence of a cationic surfactant (CTAB) endowed the material with a high porosity, and the tripodal or square-pyramidal topology of the ligand was preserved thanks to the use of the silylated Cu(II) complex. After removal of the surfactant and de-metalation, the incorporated tetraamine was quantitatively complexed by CuCl(2) and the material has shown after thermal activation that a reversible bindin…
Highly efficient separation of amines by electrokinetic chromatography using resorcarene-octacarboxylic acids as pseudo-stationary phases
1998
Abstract Resorcarene-octacarboxylic acids, macrocyclic molecules built up by four alkylidene-bridged resorcinol units, were synthesized and used as pseudostationary phases in electrokinetic chromatography (EKC). Resorcarenes provide a stable structure and good solubility in electrolytes even with organic modifiers. The high electrophoretic mobility of the resorcarene-octacarboxylic acids introduced here as pseudostationary phases is based on the eight partly deprotonated carboxylic groups. This offers a broad migration time window, which is the main parameter for the resolution of peaks. From three compounds with different alkyl chain lengths (C 1 , C 5 , C 11 ), the C 11 -resorcarene-octa-…
Use of HepG2 cell line for direct or indirect mutagens screening: comparative investigation between comet and micronucleus assays.
2003
International audience; In the present study, DNA-damage and clastogenic or aneugenic effects of genotoxic compounds were examined in a metabolically competent human cell line (HepG2 cells) using the micronucleus and the comet assays. Compounds with various action mechanisms were tested: direct mutagens such as 4-nitroquinoline-N-oxide (4-NQO) and methyl methanesulfonate (MMS) and indirect mutagens requiring biotransformation to be active such as N-nitrosodimethylamine (NDMA), benzo[a]pyrene (B[a]P) and 2-acetylaminofluorene (2-AAF). The compounds were first tested for cytotoxicity by measuring their effects on RNA synthesis inhibition in HepG2 cells. 4-NQO, B[a]P and 2-AAF were the most po…
Asymmetric Oxidative Mannich Reactions
2020
The asymmetric Mannich reaction is one of the most straightforward methodologies for the enantioselective synthesis of chiral amines. In general, asymmetric Mannich reactions involve the use of imines as electrophiles. However, in recent years, several asymmetric oxidative Mannich reactions have been reported using amines as electrophiles. This review provides an overview of these recent publications, including the different oxidants used and the scope and limitations of the different catalytic systems.
Biocompatible hydrogels based on hyaluronic acid cross-linked with a polyaspartamide derivative as delivery systems for epithelial limbal cells.
2011
The aim of this work was to evaluate the potential use of hydrogels based on hyaluronic acid (HA) chemically cross-linked with α,β-poly(N-2-hydroxyethyl) (2-aminoethylcarbamate)-D,L-aspartamide (PHEA-EDA) as substitutes for the amniotic membrane able to release limbal cells for corneal regeneration. Hydrogels, shaped as films, with three different molar ratios (X) between PHEA-EDA and HA (X = 0.5, 1.0 and 1.5) have been investigated. First, it has been evaluated their swelling ability, hydrolytic resistance in simulated physiological fluid and cell compatibility by using human dermal fibroblasts chosen as a model cell line. Then adhesion studies in comparison with collagen gel, have been pe…
Inulin-Ethylenediamine Coated SPIONs Magnetoplexes: A Promising Tool for Improving siRNA Delivery.
2015
An inulin based polycation (Inu-EDA) has been synthesized by the grafting of ethylenediamine molecules onto inulin backbone. The obtained inulin copolymer has been though to coat SPIONs (IC-SPIONs) and obtain stable magnetoplexes by complexation of IC-SPIONs with a model duplexed siRNA, for improving oligonucleotide transfection efficiency.The physical-chemical characteristics of IC-SPIONs and IC-SPIONs/siRNA magnetoplexes have been investigated by scanning and transmission electron microscopies, dynamic light scattering, FT-IR and qualitative surface elementary analysis. Cell compatibility and internalization in vitro of IC-SPIONs have been evaluated by MTS and fluorescence microscopy resp…
Interactions between Polyamines and Abiotic Stress Pathway Responses Unraveled by Transcriptome Analysis of Polyamine Overproducers
2011
Plant development and productivity are negatively regulated by adverse environmental conditions. The identification of stress-regulatory genes, networks, and signaling molecules should allow the development of novel strategies to obtain tolerant plants. Polyamines (PAs) are polycationic compounds with a recognized role in plant growth and development, as well as in abiotic and biotic stress responses. During the last years, knowledge on PA functions has been achieved using genetically modified plants with altered PA levels. In this review, we combine the information obtained from global transcriptome analyses in transgenic Arabidopsis plants with altered putrescine or spermine levels. Compa…
Production of ceramides causes apoptosis during early neural differentiation in vitro.
2000
To investigate signal transduction pathways leading to apoptosis during the early phase of neurogenesis, we employed PCC7-Mz1 cells, which cease to proliferate and begin to differentiate into a stable pattern of neurons, astroglial cells, and fibroblasts upon incubation with retinoic acid (RA). As part of lineage determination, a sizable fraction of RA-treated cultures die by apoptosis. Applying natural long-chain C(16)-ceramides as well as membrane-permeable C(2)/C(6)-ceramide analogs caused apoptosis, whereas the biologically nonactive C(2)-dihydroceramide did not. Treating PCC7-Mz1 stem cells with a neutral sphingomyelinase or with the ceramidase inhibitor N-oleoylethanolamine elevated t…
In vitro and in vivo trypanosomicidal activity of pyrazole-containing macrocyclic and macrobicyclic polyamines: their action on acute and chronic pha…
2012
The in vitro and in vivo anti- Trypanosoma cruzi activity of the pyrazole-containing macrobicyclic polyamine 1 and N-methyl- and N-benzyl-substituted monocyclic polyamines 2 and 3 was studied. Activity against both the acute and chronic phases of Chagas disease was considered. The compounds were more active against the parasite and less toxic against Vero cells than the reference drug benznidazole, but 1 and 2 were especially effective, where cryptand 1 was the most active, particularly in the chronic phase. The activity results found for these compounds were complemented and discussed by considering their inhibitory effect on the iron superoxide dismutase enzyme of the parasite, the nature…