André A. Pavia

A convenient synthesis of peracetylated glycosyl halides using bismuth(III) halides as catalysts

Abstract A new halogenation procedure for peracetylated glycopyranosides is reported, using bismuth(III) halides and halogenosilanes under very mild conditions.

Alkyl and perfluoroalkyl glycolipid-based supramolecular assemblies

Abstract New amphiphilic agents with single- or double-chain hydrogenated and/or fluorinated hydrophobic tails have been synthesized from natural disaccharides (lactose, maltose). The sugar moiety is intended to allow specific targeting of cell membrane sugar receptors. The introduction of a peptide moiety (Gly, Gly—Gly or Lys) between the hydrophilic head and the hydrophobic tail allows the adjustment of the hydrophilic—lipophilic balance (HLB). These amphiphiles are shown to form vesicles and other supramolecular assemblies readily. The morphology of these assemblies strongly depends on the components molecular structure. Glycolipids with a single fluorinated chain produced disk-like assemblies; the double-tailed analogs led to multilayer vesicles. The impact of the amino acid linkage is considerable for the double-tailed compounds: multilamellar vesicles were readily obtained when one glycine residue was interposed between the carbohydrate and the hydrophobic double tail. With a glycyl—glycine spacer unilamellar vesicles were formed. With lysine, the glycolipid molecules formed mainly disk-like lamellar structures, tubules and helical superstructures along with a few vesicles.

Efficiency of non-ionic telomeric surfactants for the solubilization of subcellular fractions proteins

Abstract We have investigated the behaviour of a new class of non-ionic telomeric surfactants termed H- TAC derived from tris-(hydroxymethyl)-aminomethane, with respect to the solubilization of subcellular proteins of rat hepatocytes and membrane antigens from tumour cells. H-TAC detergents compared to favourably with Triton X100 and Nonidet P40, tow commonly used commercial surfactants for both their solubilizing efficiency and the preservation of the tertiary structure and the antigenic specificity of the extracted proteins. In addition, H-TAC surfactants were transparent between 245 and 400 nm.

Synthesis of double-chain glycolipids derived from aspartic acid : preliminary investigation of their colloidal behavior

Abstract Double-tailed glycolipids derived from mono-, di- and tri- O -galactosyl tris-(hydroxymethyl) aminomethane and aspartic acid have been synthesized. Preliminary assessment by negative staining transmission electron microscopy of dispersions of these amphiphiles showed the formation of either vesicles, helical structures or fibers depending on the glycolipid structure.

Biocompatible non -ionic surfactants for biomedical utilization: double- tailed hydrocarbon and/or fluorocarbon synthetic glycolipids

Abstract Two classes of double-tailed hydrocarbon and/or fluorocarbon glycolipids containing either a gluco- or a galactopyranose residue in their hydrophilic head have been synthesized. The first was obtained upon opening a maltono- or lactonolactone moiety by the amino group of glycine followed by condensation of the glycine carboxylic function with a double-chain primary amine. The second involves L-lysine in place of glycine. Formation of vesicular structures upon conventional treatment was confirmed by preliminary measurements.

Amphiphilic properties of a polymerized glycolipid surfactant

N-(Undec-10-enyl)lactobionamide was synthesized and polymerized in aqueous solution by γ-irradiation of micellar solutions, leading to the polymer. The critical micellar concentration (cmc) of monomer compound was determined by surface tension measurements (3.2 × 10–3 mol dm–3); we could not detect any cmc with the polymer. The structure of the monomer and of the polymer were characterized using quasi-elastic light scattering (QELS), transmission electron microscopy (TEM) and freeze–fracture electron microscopy (FFEM). The data obtained for the polymer are in agreement with it consisting of spherical aggregates. We have investigated the micellar properties of the monomer as well as those of its corresponding polymer through the study of the solubilization of highly hydrophobic compounds and of the base-catalysed hydrolysis of hydrophobic esters. Comparative studies showed better efficiency of the polymer compared with the monomer analogue.

Synthèse de glycolipides polymérisables Dérivés du Tris(hydroxyméthyl)aminométhane: Préparation de micelles polymérisées.

Abstract We have synthesized a series of new polymerizable glycolipids derived from Tris(hydroxymethyl) aminomethane (TRIS). Galactosylation of TRIS was performed in good yield by means of ultrasounds. Polymerization of 11-N-acrylamido-N-Tris(β-D-galactopyranosyl oxymethyl)methyl undecanamide in aqueous solution by UV irradiation, led to polymerized micellar structures (A).