Development of a triculture based system for improved benefit/risk assessment in pharmacology and human food

Development of a triculture based system for improved benefit/risk assessment in pharmacology and human food

Recherche et valorisation de principes actifs antifouling isolés à partir de trois macroalgues

L'interdiction de produits antifouling à base de TBT a contraint les entreprises productrices de peintures à trouver rapidement un substituant approprié afin de limiter le phénomène de biofouling sur les coques des bateaux. Les autres biocides utilisés dans les peintures antifouling ont également soulevé de nombreuses questions quant à leurs effets sur l'environnement marin. Une alternative peut être apportée par le développement de revêtements dans lesquels les ingrédients actifs seraient des composés issus d'organismes marins. Des études récentes confirment le potentiel d'ingrédients actifs à base d'extraits d'algues marines dans les préparations antifouling. Nous avons démontré au cours de notre étude que les extraits de Sargassum muticum (Heterokonta, Fucales), de Polysiphonia lanosa (Rhodobionta, Céramiales) et de Ceramium botryocarpum (Rhodobionta, Céramiales) présentent une activité antifouling intéressante comparés aux biocides utilisés actuellement dans les peintures antifouling. Des tests d'incorporation d'extraits d'algues bruts dans des revêtements antifouling ont été effectués durant les étés 2004 et 2005 dans le port de Lorient, et les premiers résultats sont prometteurs. La purification de l'extrait éthanol/dichlorométhane de S. muticum a permis d'isoler une fraction active dont la composition a été analysée. Les techniques de Spectrométrie de Masse, de Résonance Magnétique Nucléaire et de Chromatographie en Phase Gazeuse ont mis en évidence la présence d'acide palmitique et de dioctyl phthalate dans cette fraction. Les tests effectués sur les bactéries, microalgues et spores d'algues ont démontré l'efficacité antifouling de l'acide palmitique commercial.The ban of TBT-based antifouling products has forced the coating companies to find a suitable substitute to limit the development of fouling on ship hulls. The other organic biocides used in antifouling paints are suspected to have negative effects on the marine environment. An alternative exists with the development of antifouling coatings in which active ingredients would be isolated from marine organisms. Recent studies have demonstrated the potential of active compounds extracted from marine algae in antifouling paints. We have shown in our study that the extracts from Sargassum muticum (Heterokonta, Fucales), Polysiphonia lanosa (Rhodobionta, Ceramiales) and Ceramium botryocarpum (Rhodobionta, Ceramiales) present an interesting antifouling activity, which can be compared to the activity of the organic biocides used in antifouling paints. In situ tests have been conducted during the summer 2004 and 2005 in the harbour of Lorient, and the first results of crude extracts incorporated in coatings are promising. An active fraction has been isolated after the purification of the ethanol/dichloromethane extract from S. muticum. Mass Spectrometry, Nuclear Magnetic Resonance and Gas Chromatography technics have shown the presence of palmitic acid and dioctyl phthalate in the active fraction. The tests conducted on bacteria, microalgae and algae spores have demonstrated the antifouling efficiency of the palmitic acid.LORIENT-BU (561212106) / SudocSudocFranceF

In vitro toxicity assessment of silver nanoparticles in the presence of phenolic compounds--preventive agents against the harmful effect?

The increasing commercial use of silver nanoparticles (Ag-NPs) will inevitably lead to elevated silver exposure and thus to potential human health complications. In this study the acute toxicity of Ag-NPs <20 nm alone and upon co-administration with food matrix component phenolic compounds (PCs) on the cell-based models of the gastrointestinal tract was investigated. An improved co-culture model of Caco-2 and RajiB cells was applied for more precise in vitro simulation of the gastrointestinal tract. The involvement of two major factors contributing to the toxicity of Ag-NPs, i.e. the release of Ag(+) and the induction of oxidative stress, was investigated. Ag-NPs were cytotoxic for Caco-2 cells with an EC50 of ca. 40 µg/ml. Ag-NPs led to oxidative stress starting from ca. 45 µg/ml. The epithelial barrier integrity disruption by Ag-NPs on Caco-2 cell mono- and co-cultures was established by decreased transepithelial electrical resistances and increased passages of Lucifer Yellow, a paracellular marker. Immunofluorescence staining demonstrated that Ag-NPs affect occludin and zonula occludens 1 distributions, suggesting the opening of tight junctions. Ag(+), corresponding to the release from Ag-NPs, demonstrated a partial contribution in the toxic parameters, induced by Ag-NPs. Two PCs, quercetin and kaempferol, partially protected the Caco-2 cells from Ag-NP-induced toxicity and maintained the epithelial barrier integrity, disrupted by NPs. No protective effect was observed for resveratrol. The protective effect could be beneficial and decrease the potential toxicity of ingested Ag-NPs. However, the precise mechanisms of barrier-integrity-destabilising action of Ag-NPs/Ag(+) and protective effect of PCs still require further elucidation

Comparative efficiency of macroalgal extracts and booster biocides as antifouling agents to control growth of three diatom species.

International audienceThe application of 'booster biocides' Diuron, Tolylfluanid and Copper thiocyanate inbantifouling paints, used to prevent development of biofouling, needs to be monitored before assessing their impacts on the environment. An alternative approach aims to propose eco-friendly and effective antifoulants isolated from marine organisms such as seaweeds. In this study, the effects of 'booster biocides' and the ethanol and dichloromethane extracts from a brown (Sargassum muticum) and a red alga (Ceramium botryocarpum) have been compared by algal growth inhibition tests of marine diatoms. The most efficient extracts were ethanol fraction of S. muticum and C. botryocarpum extracts with growth EC(50)=4.74 and 5.3μg mL(-1) respectively, with reversible diatom growth effect. The booster biocides are more efficient EC(50)=0.52μg mL(-1), but are highly toxic. Results validate the use of macroalgal extracts as non toxic antifouling compounds, and they represent valuable environmentally friendly alternatives in comparison with currently used biocides

in press. Investigation of the antifouling constituents from the brown alga Sargassum muticum (Yendo

Abstract One of the most promising alternatives to toxic heavy metal-based paints is offered by the development of antifouling coatings in which the active ingredients are compounds naturally occurring in marine organisms and operating as natural antisettlement agents. Sessile marine macroalgae are remarkably free from settlement by fouling organisms. They produce a wide variety of chemically active metabolites in their surroundings, potentially as an aid to protect themselves against other settling organisms. In this study, a dichloromethane extract from the brown seaweed Sargassum muticum was tested in situ and, after 2 months of immersion, showed less fouling organisms on paints in which the extract was included, compared to paints containing only copper after 2 months of immersion. No barnacles or mussels have been observed on the test rack. Identification by NMR and GC/MS of the effective compound revealed the abundance of palmitic acid, a commonly found fatty acid. Pure palmitic acid showed antibacterial activity at 44 µg mL −1 , and also inhibited the growth of the diatom Cylindrotheca closterium at low concentration (EC 50 =45.5 µg mL −1 ), and the germination of Ulva lactuca spores at 3 µg mL −1 . No cytotoxicity was highlighted, which is promising in the aim of the development of an environmentally friendly antifouling paint