Electrochemical attachment of a conjugated amino-ferrocifen complex onto carbon and metal surfaces

International audienceThe attachment of a pi-conjugated amino-ferrocifen complex was electrochemically achieved either by direct oxidation of the amino group or via the oxidation of the ferrocene moiety. In the first case, the modification consists in oxidizing, at +0.70V/SCE, the amino moiety to its radical cation, which upon deprotonation from the amino group, yields all aminyl radical that may add onto the electrode surface. Alternatively, it is demonstrated that the amine moiety can be indirectly oxidized through an intramolecular electron transfer from the amino moiety to the ferrocenyl group after oxidation of the ferrocene part at +0.40 V. This can occur thanks to the conjugated pi system of the complex. More importantly. it is demonstrated that the covalent attachment of the complex can be achieved on glassy carbon, gold, and platinum surfaces whatever the approach used. The possible mechanisms for the covalent attachment are discussed. Interestingly, it is also shown that the amino-ferrocene compound adsorbs very well likely via pi stacking between grafted and non-grafted molecules. Nevertheless, the adsorbed molecules could be easily removed after passing the electrode in an ultrasonic bath. The electrode coverage was determined under various conditions by integration of the corresponding voltammograms. (C) 2008 Elsevier B.V. All rights reserved

Étude préliminaire du traitement d’effluents contenant de l’encre de seiche par centrifugation et procédés à membranes

Il s’agit d’une étude préliminaire sur le traitement d’effluents de conditionnement de la seiche avant congélation en vue de réduire la charge polluante des rejets et de valoriser l’encre qu’ils contiennent. Deux types de procédés ont été mis en oeuvre : d’une part, la centrifugation, qui permet de fractionner la suspension d’encre de seiche entre un culot noir à DCO (Demande Chimique en Oxygène) élevée et un surnageant limpide et, d’autre part, l’ultrafiltration (UF) et la microfiltration (MF). Les flux de perméat obtenus par les deux procédés à membranes sont du même ordre de grandeur (25 à 30 L·h‑1·m‑2 sous 1,5 bar). La rétention moyenne en DCO est de 65 % et la rétention en COT (Carbone Organique Total) et azote protéique (NTK) de plus de 95 %. Cependant le colmatage irréversible de la membrane de MF conduit à préférer l’UF, plus facilement régénérable.Industries that condition fish products have to cope with the problem of processing their usually protein-rich wastewaters. An example of such an industry that discards a large amount of wastewater is the CALEMBO Company (Sfax-Tunisia), which uses 50 m3 per metric ton a day to condition cuttlefish for freezing. In order to conserve water, high-salinity bore water is sometimes used. This high salinity water is responsible for the difficulties encountered during the biological treatment of wastewaters and the recovery of valuable by-products. In this respect, membrane processes, used in the treatment and exploitation of effluents from industries that process sea products, are very attractive. The first membrane filtration trials on sea-product effluents date back to the 1980’s, but they did not result in major developments. Legislative pressures and the increasing costs of water and effluent-processing, as well as the improvement of membrane efficiencies, have made membrane treatment processes much more interesting for wastewater treatment processes. The GEPEA Laboratory at Nantes University has carried out research on membrane technologies to clean up polluted process waters, enhance substances such as soluble fish proteins, and to recover substances responsible for the flavour of bivalves and shellfish.This paper presents preliminary research on the treatment and exploitation of water used in cuttlefish conditioning. Treatment processes used include centrifugation, microfiltration and ultrafiltration. Centrifugation is used to determine the distribution of the effluent between the black residue and the clear supernatant, whereas membrane processing is used to reduce wastewater pollution and concentrate pigments.The effluent studied was reconstituted from pure cuttlefish-ink samples taken directly from the animal and salt waters of the same salinity as the bore water used by the CALEMBO Company (Table 1). The samples were reconstituted in ratios of 1 to 50 for centrifugation and 1 to 100 for membrane filtration. Centrifugation trials were carried out using a KR 22i type JOUAN centrifuge, whereas ultrafiltration and microfiltration trials were carried out using the laboratory apparatus represented in figure 1. The main characteristics of membranes used are indicated in table 2. Operating conditions were determined according to the capacities of the feed pump: transmembrane pressure Ptm = 1.5 bar, circulation velocity U = 1.5 m·s‑1 and temperature T = 25°C. The parameters measured on initial feed solutions and the fractions obtained were COD (Chemical Oxygen Demand), TOC (Total Organic Carbon) and nitrogen content (NTK). Filtration trials were carried out according to two different procedures, either with constant feed composition to determine the best operating conditions, or with increasing effluent concentration together with monitoring of the Volumetric Reduction Factor (VRF).Centrifugation of the cuttlefish-ink suspension produced two phases: a very dense black residue and relatively clear supernatant. The volumetric distribution and the COD and TOC contents of the different fractions are presented in table 3. The supernatant represented about 75% of crude effluent volume. Organic matter was concentrated in the residue and consisted primarily of suspended particles.At a constant concentration, the ultrafiltration (UF) and microfiltration (MF) processes behaved differently. A rapid drop in flux in the first minutes followed by stabilization at 30 L·h‑1·m‑2 after 30 min was observed for the MF process, whereas a rapid stabilization at approximately 25 L·h‑1·m‑2 was observed for the UF process. The drop in flux at the beginning of MF process may be due to the partial fouling of the membrane pores by melanin particles ranging in sizes from 55 to 160 nm, which are of the same order of magnitude as the membrane pores of 100 nm. On the other hand, the small decrease in flux in the case of ultrafiltration resulted essentially from the formation of a polarization layer and possible interactions between the membrane material and the solution.Batch-concentration trials were carried out for 5 and 4 h using UF and MF respectively, the operating time being dictated by the dead volume of the equipment (0.75 L). The permeate flux variation as a function of the volumetric reduction factor (VRF) is illustrated in figure 3. The MF flux was slightly higher despite the higher initial concentration of organic substances. For a VRF of 2.64 (final concentration), J = 2.8 L·h‑1·m‑2 for MF and 15.2 L·h‑1·m‑2 for UF. Despite the significantly different permeabilities of the MR and UF membranes to pure water (2690 against 34 L·h‑1·m‑2·bar‑1), their very similar J values are a consequence of the internal pore fouling of the MF membranes.Analyses performed on the initial feed samples, and on the different fractions of ink suspensions obtained by MF and UF following concentration, are presented in table 5. Retention ratios for UF were very slightly higher than those found for MF, about 65% for COD, 98% for TOC and 95% for NTK. From the point of view of pollution remediation, and considering permeate COD values, the efficiency of the membrane technique does not seem sufficient.Following ultrafiltration, membrane regeneration was possible by simply rinsing the membrane with water. On the other hand, the same procedure proved inefficient for the microfiltration (PVDF) membrane. The black pigment remained stuck to the membrane surface and most likely inside the pores as well. Furthermore, chemical regeneration (NaOH 0.1 M, 20 min, 25°C) was not enough to recover the membrane’s initial permeability.To conclude, the ultrafiltration process is better adapted to the treatment of cuttlefish washing wastewater. However, considering the level of residual COD in the ultrafiltration permeate, more efficient post-treatment techniques must be developed

Tamoxifen-like metallocifens target thioredoxin system determining mitochondrial impairment leading to apoptosis in Jurkat cells

Tamoxifen-like metallocifens (TLMs) of the group-8 metals (Fe, Ru, and Os) show strong anti-proliferative activity on cancer cell lines resistant to apoptosis, owing to their unique redox properties. In contrast, the thioredoxin system, which is involved in cellular redox balance, is often overexpressed in cancer cells, especially in tumour types resistant to standard chemotherapies. Therefore, we investigated the effect of these three TLMs on the thioredoxin system and evaluated the input of the metallocene unit in comparison with structurally related organic tamoxifens. In vitro, all three TLMs became strong inhibitors of the cytosolic (TrxR1) and mitochondrial (TrxR2) isoforms of thioredoxin reductase after enzymatic oxidation with HRP/H2O2 while none of the organic analogues was effective. In Jurkat cells, TLMs inhibited mainly TrxR2, resulting in the accumulation of oxidized thioredoxin 2 and cell redox imbalance. Overproduction of ROS resulted in a strong decrease in the mitochondrial membrane potential, translocation of cytochrome c to the cytosol and activation of caspase 3, thus leading to apoptosis. None of these events occurred with organic tamoxifens. The mitochondrial fraction of cells exposed to TLMs contained a high amount of the corresponding metal, as quantified by ICP-OES. The lipophilic and cationic character associated with the singular redox properties of the TLMs could explain why they alter the mitochondrial function. These results provide new insights into the mechanism of action of tamoxifen-like metallocifens, underlying their prodrug behaviour and the pivotal role played by the metallocenic entity in their cytotoxic activity associated with the induction of apoptosis

Recent developments of marine ingredients for food and nutraceutical applications: a review.

Remerciements à l'éditeur pour son accord de diffusion. L'article original est aussi accessible sur le site de l'éditeur à l'adresse : http://www.halieutique.org/23201b.htmlInternational audienceIn a global context of marine biological resource overexploitation, a better upgrading of fish and shellfish biomass is a challenge for the 21st century. One of the main and promising issues will be the production of marine bio-ingredients using enzymatic hydrolysis. This paper presents the key steps in the production of enzymatic hydrolysates, such as (i) enzymatic treatment for the bioconversion of solid discards, and more particularly, use of proteases, (ii) quantification of the proteolysis extend and procedures of quality-control and (iii) identification of biological activity, using in vitro and in vivo methods. In the last part, examples of marine, commercially available functional foods or nutraceutical ingredients carrying bioactive properties are presented in order to demonstrate the interest of biotechnological exploitation of marine resources

Filterability of exopolysaccharides solutions from the red microalga Porphyridium cruentum by tangential filtration on a polymeric membrane

International audienceThe red microalga Porphyridium cruentum is exploited industrially for its exopolysaccharides (EPS) and pigments production. EPS produced by P. cruentum are partially released and dissolved into the surrounding environment, they can be recovered from the culture medium after removing the cells. This paper presents a parametric study of the ultrafiltration of EPS solutions on organic membrane. The EPS solutions were produced in conditions representative of an industrial production. They were filtered at lab-scale on a flat, PES 50 kDa MWCO membrane in a complete recirculation mode of permeate and retentate. Permeate flux-transmembrane pressure (TMP) curves were established up to the limiting flux for the filtration of solutions with various values of concentration in EPS (0.10 to 1.06 kg GlcEq.m), fluid tangential velocity (0.3 to 1.2 m.s) and temperature (20 and 40 °C). The reversible and irreversible parts of fouling were evaluated for each experiment and the critical flux was determined for an intermediate EPS concentration (0.16 kg GlcEq.m). The results showed that EPS solutions had a strong fouling capacity. When filtering the lowest concentrated solution (0.10 kg GlcEq.m) with moderate fouling conditions, the overall fouling resistance was approximately half of the membrane and the share of irreversible/reversible fouling was 88 and 12%. However, the part of reversible fouling becomes predominant when approaching the limiting flux. Permeate fluxes which were obtained allow to estimate that a VRR of approximately 10 could be obtained when concentrating EPS solutions using PES membranes in flat or tubular modules but not in spiral-wound

Nanoparticles loaded with ferrocenyl tamoxifen derivatives for breast cancer treatment.

International audienceFor the first time, two organometallic triphenylethylene compounds (Fc-diOH and DFO), with strong antiproliferative activity in breast cancer cells, but insoluble in biological fluids, were incorporated in two types of stealth nanoparticles (NP): PEG/PLA nanospheres (NS) and nanocapsules (NC). Their physicochemical parameters were measured (size, zeta potential, encapsulation and loading efficiency), and their biological activity was assessed. In vitro drug release after high dilution of loaded NPs was measured by estradiol binding competition in MELN cells. The influence of the encapsulated drugs on the cell cycle and apoptosis was studied by flow cytometry analyses. Notwithstanding potential drug adsorption at the NP surface, Fc-diOH and DFO were incorporated efficiently in NC and NS, which slowly released both compounds. They arrested the cell cycle in the S-phase and induced apoptosis, whose activity is increased by loaded NS. A decrease in their antiproliferative activity by the antioxidant alpha-tocopherol indicated that reactive oxygen species (ROS) may be involved. Therefore, nanosystems, containing for the first time a high load of anticancer organometallic triphenylethylenes, have been developed. Their small size and delayed drug release, combined with their enhanced apoptotic potential, are compatible with an increased persistence in the blood and a promising antitumour activity

A [3]Ferrocenophane polyphenol showing a remarkable antiproliferative activity on breast and prostate cancer cell lines

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The replacement of a phenol group by an aniline or acetanilide group enhances the cytotoxicity of 2-ferrocenyl-1,1-diphenyl-but-1-ene compounds against breast cancer cells

International audienceWe have previously shown that conjugated ferrocenyl p-phenols show strong cytotoxic effects against both the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 breast cancer cell lines, possibly via oxidative quinone methide formation. We now present a series of analogous amine and acetamide compounds: 2-ferrocenyl-1-(4-aminophenyl)-1-phenyl-but-1-ene (Z+E-2), 2-ferrocenyl-1-(4-N-acetylaminophenyl)-1-phenyl-but-1-ene (Z-3), and their corresponding organic molecules 1-(4-aminophenyl)-1,2-bis-phenyl-but-1-ene (Z+E-4) and 1-(4-N-acetamidophenyl)-1,2-bis-phenyl-but-1-ene (Z+E-5). All of the compounds have adequate relative binding affinity values for the estrogen receptor; between 2.8% and 5.7% for ERα, and between 0.18% and 15.5% for ERβ, as well as exothermic ligand binding in in silico ER docking experiments. Compounds 2 and 3 show dual estrogenic/cytotoxic activity on the MCF-7 cell line; they are proliferative at low concentrations (0.1 μM) and antiproliferative at high concentrations (10 μM). On the MDA-MB-231 cell line, the ferrocenyl complexes 2 and 3 are antiproliferative with IC50 values of 0.8 μM for 2 and 0.65 μM for 3, while the purely organic molecules 4 and 5 show no effect. Electrochemical experiments suggest that both 2 and 3 can be transformed to oxidized quinoid-type species, analogous to what had previously been observed for the ferrocene phenols

The replacement of a phenol group by an aniline or acetanilide group enhances the cytotoxicity of 2-ferrocenyl-1,1-diphenyl-but-1-ene compounds against breast cancer cells

International audienceWe have previously shown that conjugated ferrocenyl p-phenols show strong cytotoxic effects against both the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 breast cancer cell lines, possibly via oxidative quinone methide formation. We now present a series of analogous amine and acetamide compounds: 2-ferrocenyl-1-(4-aminophenyl)-1-phenyl-but-1-ene (Z+E-2), 2-ferrocenyl-1-(4-N-acetylaminophenyl)-1-phenyl-but-1-ene (Z-3), and their corresponding organic molecules 1-(4-aminophenyl)-1,2-bis-phenyl-but-1-ene (Z+E-4) and 1-(4-N-acetamidophenyl)-1,2-bis-phenyl-but-1-ene (Z+E-5). All of the compounds have adequate relative binding affinity values for the estrogen receptor; between 2.8% and 5.7% for ERα, and between 0.18% and 15.5% for ERβ, as well as exothermic ligand binding in in silico ER docking experiments. Compounds 2 and 3 show dual estrogenic/cytotoxic activity on the MCF-7 cell line; they are proliferative at low concentrations (0.1 μM) and antiproliferative at high concentrations (10 μM). On the MDA-MB-231 cell line, the ferrocenyl complexes 2 and 3 are antiproliferative with IC50 values of 0.8 μM for 2 and 0.65 μM for 3, while the purely organic molecules 4 and 5 show no effect. Electrochemical experiments suggest that both 2 and 3 can be transformed to oxidized quinoid-type species, analogous to what had previously been observed for the ferrocene phenols