Solène Guihéneuf

Synthesis and toxicity evaluation of hydrophobic ionic liquids for volatile organic compounds biodegradation in a two-phase partitioning bioreactor

Synthesis of several hydrophobic ionic liquids (ILs), which might be selected as good candidates for degradation of hydrophobic volatile organic compounds in a two-phase partitioning bioreactor (TPPB), were carried out. Several bioassays were also realized, such as toxicity evaluation on activated sludge and zebrafish, cytotoxicity, fluoride release in aqueous phase and biodegradability in order to verify their possible effects in case of discharge in the aquatic environment and/or human contact during industrial manipulation. The synthesized compounds consist of alkylimidazoliums, functionalized imidazoliums, isoqinoliniums, triazoliums, sulfoniums, pyrrolidiniums and morpholiniums and various counter-ions such as: PF6(-), NTf2(-) and NfO(-). Toxicity evaluation on activated sludge of each compound (5% v/v of IL) was assessed by using a glucose uptake inhibition test. Toxicity against zebrafish and cytotoxicity were evaluated by the ImPACCell platform of Rennes (France). Fluoride release in water was estimated by regular measurements using ion chromatography equipment. IL biodegradability was determined by measuring BOD28 of aqueous samples (compound concentration,1mM). All ILs tested were not biodegradable; while some of them were toxic toward activated sludge. Isoquinolinium ILs were toxic to human cancerous cell lines. Nevertheless no toxicity was found against zebrafish Danio rerio. Only one IL released fluoride after long-time agitation.

Absorption of Hydrophobic Volatile Organic Compounds in Ionic Liquids and Their Biodegradation in Multiphase Systems

The coupling of absorption in a gas-liquid contactor and biodegradation in a two-phase partitioning bioreactor (TPPB) has been shown to be a promising technology for the removal of hydrophobic volatile organic compounds. The choice of the organic phase is crucial, and consequently only two families of compounds comply with the requested criteria, silicone oils and ionic liquids. These latter solvents appear especially promising owing to their absorption capacity towards hydrophobic compounds and their low volatility, as well as the possibility of IL tailoring, allowing a fine-tuning of their physicochemical properties, leading to a wide range of products with various characteristics. Some results on common ionic liquids are highlighted in this chapter: biodegradation rates reported by some authors show that phenol biodegradation in the presence of ILs is up to 40 % higher than those obtained in other multiphase reactors; there is a strong affinity of toluene and DMDS for imidazolium salts, [C4Mim][PF6] or [C4Mim][NTf2]. Performance improvements may be expected from the tailoring of ionic liquid structure, especially towards toxicity reduction. Positive results recorded after cell acclimation to target compounds let expect an important gain from more complex acclimation strategies, including microbial acclimation to both ionic liquids and pollutants.

Marine-Derived 2-Aminoimidazolone Alkaloids. Leucettamine B-Related Polyandrocarpamines Inhibit Mammalian and Protozoan DYRK & CLK Kinases

A large diversity of 2-aminoimidazolone alkaloids is produced by various marine invertebrates, especially by the marine Calcareous sponges Leucetta and Clathrina. The phylogeny of these sponges and the wide scope of 2-aminoimidazolone alkaloids they produce are reviewed in this article. The origin (invertebrate cells, associated microorganisms, or filtered plankton), physiological functions, and natural molecular targets of these alkaloids are largely unknown. Following the identification of leucettamine B as an inhibitor of selected protein kinases, we synthesized a family of analogues, collectively named leucettines, as potent inhibitors of DYRKs (dual-specificity, tyrosine phosphorylation regulated kinases) and CLKs (cdc2-like kinases) and potential pharmacological leads for the treatment of several diseases, including Alzheimer’s disease and Down syndrome. We assembled a small library of marine sponge- and ascidian-derived 2-aminoimidazolone alkaloids, along with several synthetic analogues, and tested them on a panel of mammalian and protozoan kinases. Polyandrocarpamines A and B were found to be potent and selective inhibitors of DYRKs and CLKs. They inhibited cyclin D1 phosphorylation on a DYRK1A phosphosite in cultured cells. 2-Aminoimidazolones thus represent a promising chemical scaffold for the design of potential therapeutic drug candidates acting as specific inhibitors of disease-relevant kinases, and possibly other disease-relevant targets.

Impact of activated sludge acclimation on the biodegradation of toluene absorbed in a hydrophobic ionic liquid

Classical hydrophobic ionic liquids such as 3-butyl-1-methylimidazolium bis(trifluoroethylsulfonyl)imide or 3-butyl-1-methylimidazolium hexafluorophosphate application, as a non-aqueous liquid phase in a two-partitioning bioreactor to biodegrade hydrophobic volatile organic compounds by activated sludge, have been already reported in the literature, especially when the activated sludge was beforehand acclimated to the targeted volatile organic compound. In this study, four hydrophobic ionic liquids were used as non-aqueous liquid phase in a two-phase partitioning bioreactor to biodegrade toluene using non-acclimated activated sludge. The preliminarily results allowed to select two ionic liquids, 1-octylisoquinolinium bis(trifluoromethylsulfonyl)imide and allyl-diethylsulfonium bis(trifluoromethylsulfonyl)imide. The activated sludge was acclimated to both toluene and the considered ionic liquid. The results were compared to those obtained with non-acclimated activated sludge. The use of non-acclimated activated sludge for toluene biodegradation led to long lag times and low biodegradation rates. Thus, the acclimation to toluene improved the biodegradation rates; however, acclimation to both toluene and ionic liquid did not result in a significant improvement in the biodegradation rate compared to an acclimation to toluene alone. The activated sludge acclimation had a positive impact on toluene biodegradation and allowed to totally overcome the inhibitory effect of the presence of ionic liquid. The most relevant acclimation strategy seems to be a prior acclimation to toluene, whereas acclimation to the non-aqueous liquid phase can be achieved during the culture, namely by performing successive batches for instance, or a continuous operation.

Evolution of DMSP (dimethylsulfoniopropionate) biosynthesis pathway: Origin and phylogenetic distribution in polyploid Spartina (Poaceae, Chloridoideae)

DMSP (dimethylsulfoniopropionate) is an ecologically important sulfur metabolite commonly produced by marine algae and by some higher plant lineages, including the polyploid salt marsh genus Spartina (Poaceae). The molecular mechanisms and genes involved in the DMSP biosynthesis pathways are still unknown. In this study, we performed comparative analyses of DMSP amounts and molecular phylogenetic analyses to decipher the origin of DMSP in Spartina that represents one of the major source of terrestrial DMSP in coastal marshes. DMSP content was explored in 14 Spartina species using 1H Nuclear Magnetic Resonance (NMR) spectroscopy and Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS). Putative genes encoding the four enzymatic steps of the DMSP biosynthesis pathway in Spartina were examined and their evolutionary dynamics were studied. We found that the hexaploid lineage containing S. alterniflora, S. foliosa and S. maritima and their derived hybrids and allopolyploids are all able to produce DMSP, in contrast to species in the tetraploid clade. Thus, examination of DMSP synthesis in a phylogenetic context implicated a single origin of this physiological innovation, which occurred in the ancestor of the hexaploid Spartina lineage, 3-6MYA. Candidate genes specific to the Spartina DMSP biosynthesis pathway were also retrieved from Spartina transcriptomes, and provide a framework for future investigations to decipher the molecular mechanisms involved in this plant phenotypic novelty that has major ecological impacts in saltmarsh ecosystems.