Dihydroxyacetone conversion into lactic acid in an aqueous medium in the presence of metal salts: influence of the ionic thermodynamic equilibrium on the reaction performance

International audienceThe catalytic conversion of dihydroxyacetone (DHA) to lactic acid (LA) via pyruvaldehyde (PA) in aqueous media was studied using different homogeneous metal salts. A kinetic model was developed and the parameters corresponding to each reaction steps were estimated. Agreement between experiments and simulated results was excellent and the performance of the different catalysts was consistent with previous studies described in the literature. Aluminium salts, which show the best performance, were tested in a whole range of concentrations and at different pH, in order to identify the catalytically active ionic species. It was confirmed that the DHA to pyruvaldehyde (PA) dehydration step is catalyzed by both Brønsted and Lewis acids whereas the consecutive reaction of PA to LA is solely catalyzed by Lewis acids. Moreover, comparing thermodynamic analysis of the reaction media and kinetic parameters demonstrated that cationic hydroxyl-aluminium complexes [Al(OH)h] (3-h)+ formed in situ by the hydrolysis of the aluminium aqua complexes like [Al(OH2)6] 3+ are the most active Lewis acids

Transformation of cellulose into non-ionic surfactants in a one pot catalytic process

Alkyl glucosides surfactants have been synthesized by a cascade process which involves the methanolysis of cellulose into methyl glucosides followed by the transacetalization with n-octanol. The first step was carried out using methanol as solvent and acid catalysts (such as inorganic acids, heteropolyacids, ion-exchange resins or modified carbon materials). Subsequently long chain alkyl glucosides can be obtained in a second step by transacetalization which involves the reaction of methyl glucosides with a fatty alcohol using the same acid catalyst. The overall process was performed under mild conditions. Amorphous sulfonated carbon catalyst achieved the best results for the complete conversion of cellulose in methanol at 200 οC with yields higher than 80 % of methyl α,β-glucopyranosides. Moreover, this material containing -SO3H groups is optimal to perform the second step obtaining octyl and decyl glucosides in yields higher than 73 % at 120 οC. In addition, catalyst reusability has been tested showing that sulfonated carbon catalyst (C-SO3H) can be reused with only a slightly decrease of its activity after four consecutive cycles.Financial support by Consolider-Ingenio 2010 (Project Multicat), Spanish MICINN Project (CTQ-2015-67592-P), Generalitat Valenciana (Prometeo Program) and Program Severo Ochoa is gratefully acknowledged.Climent Olmedo, MJ.; Corma Canós, A.; Iborra Chornet, S.; Martínez Silvestre, S. (2016). Transformation of cellulose into non-ionic surfactants in a one pot catalytic process. ChemSusChem. 9(24):119-128. https://doi.org/10.1002/cssc.201600977S11912892

Molecular and cellular impact of Psoriasin (S100A7) on the healing of human wounds

Psoriasin, which is also known as S100A7, is a member of the S100 protein family, a group of calcium‑responsive signalling proteins. Psoriasin expression remains high in patients with psoriasis, whereas it is downregulated in patients with invasive breast carcinoma. This observation suggests that this protein may be a notable marker of keratinocyte function and differentiation during wound healing. The aim of the present study was to determine the cellular impact of Psoriasin in keratinocytes, which are the primary cell type associated with wound healing. Psoriasin expression in wound tissues was examined using reverse transcription‑quantitative polymerase chain reaction and immunochemical staining. Knockdown of Psoriasin in HaCaT cells was performed using anti‑Psoriasin ribozyme transgenes and the effect on growth, adhesion and migration of keratinocytes was subsequently determined using in vitro cellular functional assays. Psoriasin expression is upregulated in wounds, particularly at the wound edges. The present study demonstrated that Psoriasin is expressed in keratinocytes and is a fundamental regulator of keratinocyte migration. Significant increases in the rate of keratinocyte adhesion, migration and growth were observed in Psoriasin‑deficient cells (P<0.01 vs. control). Application of small inhibitors identified the potential association of neural Wiskott‑Aldrich syndrome protein, focal adhesion primase and rho‑associated protein kinase signalling pathways with Psoriasin‑regulated cell adhesion and motility. In conclusion, Psoriasin serves an important role in the wound healing process, suggesting that it may be utilized as a potential wound healing biomarker

"Acid catalyzed transformation of Lignocellulosic Biomass in water and SC organic solvents"

SSCI-VIDE+CDFA+NESInternational audienceNon

Valorisation of lignocellulosic biomass: liquefaction process in supercritical organic solvents

International @ CDFA+NESInternational audienceNon

Towards sustainable heterogeneous catalytic steps from hexoses or pentoses to 2,5-furandicarboxylic acid

SSCI-VIDE+CDFA+NESInternational audience"Bioresources and green chemistry

Potential of heterogeneous acid and base catalysis for lignocellulosic biomass conversion into value added products

International @ BIOVERT+NESInternational audienceNon

French-Dutch meeting on Biobased aromatics

BIOVERT+NESTowards sustainable catalytic steps from hexoses to HMF derivative

"Acid catalyzed transformation of Lignocellulosic Biomass in water and SC organic solvents"

SSCI-VIDE+CDFA+NESInternational audienceNon