Biomimetic approaches to understand how mycosubtilin, an antifungal lipopeptide, can interact with cytoplasmic membranes

Poster (2009)

Mycosubtilin is a natural cyclic lipopeptide characterized by its strong antifungal activities. It has been demonstrated that the cytoplasmic membranes of the sensitive cells are the target of this ... [more ▼]

Mycosubtilin is a natural cyclic lipopeptide characterized by its strong antifungal activities. It has been demonstrated that the cytoplasmic membranes of the sensitive cells are the target of this antifungal lipopeptide. In spite of the fact that some properties of mycosubtilin have been highlighted, the molecular mechanism of its biological action remains partially understood. In view of this, we investigated the interactions between mycosubtilin and cytoplasmic membranes by using biomimetic systems such as lipid monolayers at the air-water interface and lipid multilayers. These interactions were examined by different methods (pressure/area isotherms, kinetic measurements of the interfacial adsorption, Brewster angle microscopy, infrared and NMR spectroscopies). We showed that mycosubtilin does not interact strongly with the C=O ester residues of phospholipids in multilayers, while it modifies the transition temperature of the alkyl chains. It was also demonstrated that these interactions depend on the phospholipid phase. Varying the lipid composition of monolayers allowed us to demonstrate an original behavior of mycosubtilin in the presence of sterol. This suggests a mycosubtilin-sterol affinity. [less ▲]

A biomimetic synthesis of coelenterazine analogs

in Tetrahedron Letters (2002), 43(17), 3161-3164

N-(Trifluoroacetyl)dehydrodipeptides 2–3 were coupled to aminomethylene dimethylacetal derivatives 4–5. The resulting pseudo-tripeptides 6 were stepwise deprotected (carbonyl function (7) then amine ... [more ▼]

N-(Trifluoroacetyl)dehydrodipeptides 2–3 were coupled to aminomethylene dimethylacetal derivatives 4–5. The resulting pseudo-tripeptides 6 were stepwise deprotected (carbonyl function (7) then amine function) and in situ cyclized into imidazolopyrazines 1. [less ▲]

Biomolecular comparison of bacteriological caecal flora with and without Epizootic Rabbit Enteropathy (ERE) contamination

Poster (2009, April 01)

Biomolecules in multilayer film for antimicrobial and easy-cleaning stainless steel surface applications

in Biofouling (2010), 26(6), 645-656

Microorganisms are able to attach to, grow on, and ultimately form biofilms on a large variety of surfaces, such as industrial equipment, food contact surfaces, medical implants, prostheses and operating ... [more ▼]

Microorganisms are able to attach to, grow on, and ultimately form biofilms on a large variety of surfaces, such as industrial equipment, food contact surfaces, medical implants, prostheses and operating rooms. Once organized into biofilms, bacteria are difficult to remove and kill, which increases the risk of cross-contamination and infection. One way to address the problem may thus be to develop antibacterial, anti-adhesion, ‘easy cleaning’ surfaces. In this study, stainless steel (SS) surfaces with antibacterial properties were created by embedding several antimicrobial peptides in a multilayer film architecture. The biocidal effect of these surfaces was demonstrated against both Gram-positive and Gram-negative bacteria according to two ISO tests. Also, coating SS surfaces with either mucin or heparin led to a reduction of <i>S. epidermidis</i> adhesion of almost 95% <i>vs</i> the bare substratum. Finally, by combining both antibacterial and anti-adhesion biomolecules in the same multilayer film, SS surfaces with better cleanability were produced. This surface coating property may help to delay the buildup of a dead bacterial layer which is known to progressively reduce exposure of the coating, leading to an undesirable decrease in the antibacterial effect of the surface. [less ▲]

Biomonitoring genotoxicity and cytotoxicity of Microcystis aeruginosa (Chroococcales, Cyanobacteria) using the Allium cepa test

in Science of the Total Environment (2012), 432

Biomonitoring of dioxins and PCBs in human serum: SPE-LC-GC-IDHRMS for high throughput sub-PPT level measurements

in Organohalogen Compounds (2006), 68

Les biopesticides

Poster (1993, October)

Biopharmaceutical aspects of the development of a sulfamethazine oral sustained release bolus for lambs

in Journal of Controlled Release (1995), 35

Pharmacokinetic parameters of sulfamethazine (SMZ) administered intravenously or orally either as an aqueous solution or as a lipid matrix formulation, were determined in young lambs. The value of the ... [more ▼]

Pharmacokinetic parameters of sulfamethazine (SMZ) administered intravenously or orally either as an aqueous solution or as a lipid matrix formulation, were determined in young lambs. The value of the rate constant for elimination (ke) for the intravenous solution was 0.18 h−1 compared to 0.10 h−1 for the oral aqueous solution. The absolute bioavailability of the oral solution was about 75%. A lipid matrix containing SMZ and a high density excipient is able to be retained in the reticulo-rumen and to produce a sustained release of the drug for at least 100 h provided that the mechanical strength of the bolus is sufficient. The pharmacokinetic data obtained with the lipid matrix show a release profile with two pulses due to both diffusion and erosion mechanisms. Plasma levels are maintained above the MIC of SMZ during 100 h with an absolute bioavailability of 51.7% [less ▲]

Biophysical Approaches Modelling the Interaction of the Antimicrobial Mycosubtilin with Sterol‐Containing Membranes of Sensitive Cells

Poster (2012, July)

Biophysical study of psychrophilic ans thermophilic trigger factors: a model for extremophilic protein stability

Poster (2010, September)