Thierry Benvegnu

Original Synthesis of Linear, Branched and Cyclic Oligoglycerol Standards

A variety of authentic standards of linear, branched and cyclic oligomers of glycerol, with well-defined structures and degrees of polymerisation from 2 to 5, have been efficiently synthesised. Linear oligomers were obtained by means of a convergent approach based on regioselective opening of bis(epoxides) with solketal; branched compounds were synthesised using oxidative cleavage of the corresponding anhydrohexitols as the key step. A 6-exo-trig halocyclisation reaction involving heteroatom-tethered unsaturated alcohols permitted an efficient synthesis of the precursors of selected cyclic dimers; larger cyclic oligomers were prepared by two one-pot Williamson reactions using a ditriflate derived from diglycerol. All these methodologies permitted further scaling up.

Gene transfer by chemical vectors, and endocytosis routes of polyplexes, lipoplexes and lipopolyplexes in a myoblast cell line.

Chemical vectors are widely developed for providing safe DNA delivery systems. It is well admitted that their endocytosis and intracellular trafficking are critical for the transfection efficiency. Here, we have compared the endocytic pathways of lipoplexes, polyplexes and lipopolyplexes formed with carriers of various chemical compositions. Engineered C2C12 mouse myoblast cells expressing Rab5-EGFP, Rab7-EGFP or Cav1-GFP were used to monitor the location of the plasmid DNA into the endocytic compartments by real time fluorescence confocal microscopy. We observed that (i) DNA complexes made with dioleyl succinyl paromomycin:O,O-dioleyl-N-histamine phosphoramidate (DOSP/MM27) liposomes or histidinylated lPEI (His-lPEI) allowing the highest transfection efficiency displayed a positive ζ potential and were internalized by clathrin-mediated endocytosis, (ii) DOSP/MM27 lipoplexes were 6-times more internalized than His-lPEI polyplexes, (iii) all negatively charged DNA complexes lead to less efficient transfection and entered the cells via caveolae and (iv) lipopolyplexes allowing high transfection efficiency were weakly internalized via caveolae. Our results indicate that the transfection efficiency is better correlated with the nature of the endocytic pathway than with the uptake efficacy. This study shows also that engineered cells expressing specific fluorescent compartments are convenient tools to monitor endocytosis of a fluorescent plasmid DNA by real time fluorescence confocal microscopy.

Archaeosomes based on synthetic tetraether-like lipids as novel versatile gene delivery systems

Novel cationic liposomes, termed archaeosomes, based on mixtures of neutral/cationic bilayer-forming lipids and archaeobacterial synthetic tetraether-type bipolar lipids show efficient in vitro gene transfection properties and represent a new approach for modulating the lipidic membrane fluidity of the complexes they form with DNA.

Archaeosomes based on novel synthetic tetraether-type lipids for the development of oral delivery systems

The in vitro stability of archaeosomes made from novel synthetic membrane-spanning tetraether lipids was evaluated in conditions mimicking those of oral route application in terms of bile salts, serum and low pH..

Liquid chromatography of polyglycerol fatty esters and fatty ethers on porous graphitic carbon and octadecyl silica by using evaporative light scattering detection and mass spectrometry

A liquid chromatographic method has been developed for the analysis of polyglycerol fatty esters and fatty ethers which are non-ionic surfactants. Two methods were compared using either octadecyl silica or porous graphitic carbon. The octadecyl silica system with a hydroorganic mobile phase enables to compare the hydrophobic behavior of the compounds. The porous graphitic carbon enables the separation of the diastereoisomers. Detection of these non-UV-absorbing compounds was achieved by evaporative light scattering detection. Identification of isomers was performed by mass spectrometry.

Oligomannuronates from Seaweeds as Renewable Sources for the Development of Green Surfactants

The development of surfactants based on natural renewable resources is a concept that is gaining recognition in detergents, cosmetics, and green chemistry. This new class of biodegradable and biocompatible products is a response to the increasing consumer demand for products that are both greener, milder, and more efficient. In order to achieve these objectives, it is necessary to use renewable low-cost biomass that is available in large quantities and to design molecular structures through green processes that show improved performance, favorable ecotoxicological properties and reduced environmental impact. Within this context, marine algae represent a rich source of complex polysaccharides and oligosaccharides with innovative structures and functional properties that may find applications as starting materials for the development of green surfactants or cosmetic actives. Thus, we have developed original surfactants based on mannuronate moieties derived from alginates (cell-wall polyuronic acids from brown seaweeds) and fatty hydrocarbon chains derived from vegetable resources. Controlled chemical and/or enzymatic depolymerizations of the algal polysaccharides give saturated and/or unsaturated functional oligomannuronates. Clean chemical processes allow the efficient transformation of the oligomers into neutral or anionic amphiphilic molecules. These materials represent a new class of surface-active agents with promising foaming/emulsifying properties.

Diels-alder reactions on linear polyenes, selectively protected as their tricarbonyl-iron complexes.

Abstract The first examples of Diels-Alder reactions using dienophiles or a diene bearing butadienetricarbonyliron moieties are described. These highly stereoselective reactions are useful for the synthesis of polycyclic derivatives via tandem cycloadditions.

Direct analysis of industrial oligoglycerols by liquid chromatography with evaporative light-scattering detection and mass spectrometry

SummaryA liquid chromatographic method has been developed for analysis of industrial polyglycerols, precursors of polyglycerol fatty esters, which are non-ionic surfacetants. The method utilizes two complementary chromatographic systems: porous graphitic carbon and an aminopropyl polymer with an acetonitrile-water mixture as mobile phase. Detection of these non-UV absorbing compounds was effected by means of evaporative light-scattering detection. Their structures were determined by comparison of their retention with that of synthesized standards, and by mass spectrometry.

Surfactants from Renewable Sources: Synthesis and Applications

Publisher Summary The development of surfactants based on natural renewable resources is a concept that is gaining recognition from the detergent and cosmetic industries. This new class of biocompatible and biodegradable surfactants should be a response to the increasing consumer demand for products that are both greener and more powerful. The present chapter reviews the major contributions to the synthesis and characterization of amphiphilic molecules derived from natural oils and fats (lipophilic moiety) and incorporating sugar-, polyol- or ionic-type residues as the polar headgroups. It covers various aspects of their synthesis, industrial production, applications, and regulations.

An efficient synthesis of analogues of unsymmetrical archaeal tetraether glycolipids

Unsymmetrical tetraether analogues of glycolipids found in archaebacteria, possessing either two different carbohydrate units or a saccharidic moiety and a phosphate group as polar heads and a quasi-macrocyclic lipid core, are efficiently synthesized from versatile chiral building blocks.