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International audience; The most prevalent form of Charcot-Marie-Tooth disease (CMT type 1A) is characterized by duplication of the PMP22 gene, peripheral dysmyelination and decreased nerve conduction velocities leading to muscle weakness. Recently, oxidative stress was reported as a feature in CMT1A patients. Curcumin exhibits antioxidant activities and has shown beneficial properties on peripheral nerves. However, curcumin presents unfavorable pharmacokinetics. We developed curcumin-cyclodextrin/cellulose nanocrystals (Nano-Cur) to bypass this limitation. The present study investigated the therapeutic potential of Nano-Cur in vitro in Schwann cells (SCs) and in vivo in the transgenic CMT1A rat model. In vitro, Nano-Cur treatment (0.01 μM for 8 h) reduced reactive oxygen species and improved mitochondrial membrane potential in CMT1A SCs. Moreover, Nano-Cur treatment (0.01 μM for 1 week) increased the expression of myelin basic protein in SC/neuron co-cultures. Preliminary in vivo experiments carried out in WT rats showed that intraperitoneal (i.p.) injection of Nano-Cur treatment containing 0.2 mg/kg of curcumin strongly enhanced the bioavailability of curcumin. Afterwards, in 1-month-old male CMT1A rats, Nano-Cur treatment (0.2 mg/kg/day, i.p. for 8 weeks) significantly improved sensori-motor functions (grip strength, balance performance, and mechanical and thermal sensitivities). Importantly, sensory and motor nerve conduction velocities were improved. Further histological and biochemical analyses indicated that myelin sheath thickness and myelin protein expression (myelin protein zero and PMP22) were increased. In addition, oxidative stress markers were decreased in the sciatic nerve and gastrocnemius muscle. Finally, Nrf2 expression and some major antioxidant enzymes were increased in sciatic nerve. Therefore, Nano-Cur significantly improved cellular, electrophysiological, and functional features of CMT1A rats.

International audience; This paper describes the preparation of two chalcone/β-cyclodextrin/cellulose-nanocrystals complexes and thestudy of their antiproliferative activities against two colorectal and two prostatic cancer cell lines. The aim of thiswork was to enhance hydrosolubility of chalcones thanks to the hydrophilic character of cellulose nanocrystals.These latter were linked, through ionic interactions, to a cationic derivative of β-cyclodextrins whose lipophiliccavity allowed the encapsulation of hydrophobic chalcones: 3-hydroxy-3′,4,4′,5′-tetramethoxychalcone (1) and3′,4,4′,5′-tetramethoxychalcone (2). First, we showed that encapsulation allowed hydrosolubilization of chalcones.Then, chalcone/β-cyclodextrin/cellulose-nanocrystals complexes demonstrated enhanced in vitro antiproliferativeactivities, compared to the corresponding free-chalcones.

A new gold nanoparticle-based construct has been designed to hydrophobic drugs delivery into cancer cells. Cyclodextrin scaffolds adsorbed on polyethyleneimine-coated gold nanoparticles (AuNP@PEI@CD) have been used to encapsulate hydrophobic tetrapyrrolic compounds consisting of gold complexes of 5,10,15,20-tetraphenyl porphyrin (AuTPPCl) and 5-(4-acetoxyphenyl)-10,15,20-triphenyl porphyrin (AuTPPOAcCl). These two nanoparticles have been tested for their cytotoxic activities against the two colorectal cancer cell lines HT-29 and HCT-116 and have shown significant increases in toxicity when compared to the corresponding non-vectorized tetrapyrrolic macrocycles.

Two protoporphyrin IX (PpIX) adamantane derivatives were synthesized and then metallated with zinc. The Zn-PpIX derivatives, exhibiting a high singlet oxygen quantum yield, were tested for their photodynamic activity against the HT-29 cell line. In order to enhance their water-solubility and their cellular bioavailability, these photosensitizers were encapsulated into the hydrophobic cavity of cyclodextrins (CD) previously attached to cellulose nanocrystals (CNCs) via electrostatic interactions. Under illumination, the encapsulated adamantanyl-porphyrins exerted an enhanced in vitro cytotoxicity, as compared with the corresponding free photosensitizers.

International audience; We describe the synthesis of cellulose nanocrystals (CNCs) complexed to siRNA. PEI (600 Da) was first covalently attached to CNCs by reductive amination reaction, then CNCs-PEI were loaded with siRNA, resulting in the formation of CNCs-PEI-siRNA particles, strongly stabilized by ionic interactions. Efficient cellular uptake of these particles was monitored by ethidium bromide staining. Not only did CNCs-PEI show no cytotoxicity at the studied concentrations, but they also protected siRNA from degradation and favored its delivery into the cells. This siRNA (siRNA killer) is able to silence the expression of cell cycle genes and to induce cell death by apoptosis. Therefore, this study suggests that these CNCs-PEI are promising non-viral nanovehicles for siRNA delivery and for efficient anti-tumor strategy.

To enhance the solubility of two new photosensitizers (PS), obtained from natural products ( Spirulina maxima and Rhodobacter sphaeroides ), derivatization of purpurin-18 1 and bacteriopurpurin-18 3 with a cationic polymer: PEI (polyethylenimine) led to the production of polyaminated chlorins 5 – 6 and bacteriochlorins 7 – 8 , respectively. These new water-soluble photosensitizers have been designed for their potential use in PDT: they are endowed with facilitated accumulation into cancer cells, and their respective Q bands, in the near-infrared region of the visible spectrum, span over the deepest therapeutic window of human tissues.

International audience; This Letter reports the synthesis and the characterization of two new water-stable and soluble photosensitizer-conjugated magnetic nanoparticles (PS-MNPs) composed of an iron oxide magnetic core coated with a biocompatible dextran shell bearing polyaminated chlorin p6. Designed to improve cancer cell targeting, these photosensitizers were assayed for their antitumour activity against two variants of B16 mouse melanoma cell line (B16F10 and B16G4F, with or without melanin, respectively). Cell viability measurements demonstrated that PS-MNPs were more phototoxic than PEI-chlorin p6 making these photosensitizers promising for further in vitro and in vivo investigations.

Background Photodynamic therapy, using porphyrins as photosensitizers (PS), has been approved in treatment of several solid tumors. However, commonly used PS induce death but also resistance pathways in cancer cells and an alteration of surrounding normal tissues. Because polyamines (PA) are actively accumulated in cancer cells by the Polyamine Transport System (PTS), they may enable PS to specifically target cancer cells. Here, we investigated whether new protoporphyrin IX-polyamine derivatives were effective PS against prostate cancer and whether PA increased PDT specificity after 630 nm irradiation. Methods CHO and CHO-MG cells (differing in their PTS activity) were used to assess efficacy of polyamine vectorization. MTT assays were performed on human prostate non-malignant (RWPE-1) and malignant (PC-3, DU 145 and LNCaP) cell lines to test PS phototoxicity. ROS generation, DNA fragmentation and cell signalling were assessed by ELISA/EIA, western-blots and gel shift assays. Finally, PS effects were studied on tumor growth in nude mice. Results Our PS were more effective on cancer cells compared to non-malignant cells and more effective than PpIX alone. PpIX-PA generated ROS production involved in induction of apoptotic intrinsic pathways. Different pathways involved in apoptosis resistance were studied: PS inhibited Bcl-2, Akt, and NF-κB but activated p38/COX-2/PGE2 pathways which were not implicated in apoptosis resistance in our model. In vivo experiments showed PpIX-PA efficacy was greater than results obtained with PpIX. Conclusions All together, our results showed that PpIX-PA exerted its maximum effects without activating resistance pathways and appears to be a good candidate for prostate cancer PDT treatment.

International audience; Polymer Electrolyte Fuel Cells operating in alkaline media present various advantages. As an alternative to fossil origin polymer electrolytes, the synthesis of crosslinked anion exchange membranes based on cellulose is described in this paper. Using cellulose p-toluenesulfonate derivatives, a carbohydrate polymer bearing quaternary ammonium moieties is synthesized by a reaction with 1,4-diazabicyclo[2.2.2]octane. Membranes are then obtained by crosslinking this cationic polymer with diiodobutane. IR and NMR spectroscopy together with elemental analysis confirmed structures of the different intermediates. In order to complete this study, Ionic Exchange Capacity, Water Uptake and conductimetry data are also provided.

International audience; Porphyrin-polyamine conjugates bearing two (cis or trans position) or four spermidine or spermine units were synthesized. We studied the photostability, the hydrophilic/lipophilic balance of porphyrin-polyamine derivatives and the production of singlet oxygen. All these compounds possess physicochemical features required for their use in PDT. Then, we investigated the photocytotoxic efficacy of these porphyrin-polyamine derivatives and the cell death pathway implicated. All compounds appear to be more efficient than Photofrin® to induce HaCat and MCF7 cell death, essentially by apoptosis. Collectively, these data show that porphyrin-polyamine conjugates could be promising phototherapeutic agents.

International audience; Bogolan is a traditional dyeing technique, deeply rooted in Mali. It uses local clays from Niger River region and a leave extract from N'galama trees (Anogeissus leiocarpa). The clay contains a significant amount of iron (hydr)oxides, mainly akaganeite. It reacts with N'galama coating onto cotton to form black or brown colors. UV/Vis and IR spectroscopy indicated very similar behavior of N'galama leaves extract and carboxylic aromatic acids, mainly ellagic or gallic acids, which form dark colored complexes with iron. Since iron (hydr)oxides are coated on clay mineral particles, they contribute to the fixation of the clay mineral particles and also cause the dark color. X-ray diffraction of oriented tissue and SEM observations confirmed the presence of clay particles attached on the fiber surface.

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.

International audience; We report an efficient synthesis of tetra‐ and hexa‐substituted carbohydrate‐coated compounds, which we have named "star‐like" surfactants, starting from either α‐methylglucose or myo‐inositol as a central core. The synthesis explores a new approach to such multipolar compounds using [3+2] copper (I)‐catalyzed cycloadditions to attach the respective building blocks.

International audience; Synthesis of a triazole-linked 3'-5' thymidine dimer making use of 1,3-dipolar cycloaddition is described. The azido-precursor was obtained by regioselective chlorination of thymidine, followed by azidation. The second precursor, a propargyl derivative, was obtained by selective 3'-O-alkylation of thymidine. Two 'click systems' were compared to obtain the desired dimer. These reactions were performed by microwave irradiation.

A new anti-cancer drug delivery system, based on gold nanoparticles, has been designed for hydrophobic active compounds. The system is a conjugate of gold/polyethyleneimine (AuNPs/PEI) nanoparticles and sulphated β-cyclodextrin (CD). Anionic cyclodextrin was attached to the positively charged AuNPs/PEI nanoparticles by ionic bonds. Tanshinone IIA and α-mangostin were extracted, purified and encapsulated into the AuNPs/PEI/CD nanoparticles. In vitro preliminary cell viability assays against prostate cancer cell lines PC-3 and DU145 showed that encapsulation resulted in increased cytotoxicity.

International audience; The synthesis of curcumin-cyclodextrin/cellulose nanocrystals (CNCx) nano complexes was performed. CNCx were functionalized by ionic association with cationic β-cyclodextrin (CD) and CD/CNCx complexes were used to encapsulate curcumin. Preliminary in vitro results showed that the resulting curcumin-CD/CNCx complexes exerted antiproliferative effect on colorectal and prostatic cancer cell lines, with IC50s lower than that of curcumin alone.

To determine potential mechanisms by which PpIX-PA (protoporphyrin IX-polyamines; PpIX is coupled with two molecules of spermidine (PpIX-dSd) or spermine (PpIX-dSm)) inhibited prostate cancer cell viability, we studied its effects on mitochondrial membrane potential because alterations in mitochondrial structure and function have been shown to play a crucial role at early stages of apoptosis

International audience; The synthesis of hydrophobic plastic films was performed by acylation of agaroids with lauroyl chloride in the N,N-dimethylacetamide homogeneous system. All the plastic films were characterized by FT-IR spectroscopy and their degrees of substitution (DS) was deduced from their 1H-NMR spectra. In addition, thermomechanical feature of plastic films were analyzed and compared to those obtained from other kinds of hydrophobic plastic films. Latin square design of experiments helped us to determine optimized experimental conditions and identify the most important factors. Hence, mild conditions of acylation (90∘C, 1 eq/OH of lauroyl chloride, 1 eq/OH of 4-dimethylaminopyridine, 5,min) led to the production of highly substituted plastic films (DS = 3.62; maximum 4) with a high weight yield (211%) displaying mechanical properties close to polyethylene low density.

International audience; Activated charcoal treated with nitric acid was used as a solid catalyst for synthesis of meso-arylporphyrins by condensation of pyrrole with convenient arylaldehydes in a solvent-free system. The reaction took place at 200°C and porphyrins were obtained in good yields. This environment-friendly method avoids the use of detrimental solvents and toxic catalysts.

This paper reports the synthesis of new chlorin–polyamine conjugates designed to improve the targeting of cancer cells. Photocytotoxic activity of these photosensitizers was tested against human chronic myelogenous leukemia cells (K562) and compared to the effects of Photofrin II ® and chlorin e 6 .

International audience; The chemical mechanism displayed in the sorption of heavy metal cations on barks was discussed through a modelling study of adsorption in relation to the nature of the ligand borne by the chemical components of the bark sorbent. The adsorption isotherms of five heavy metal cations (Cr3 +, Cu2 +, Ni2 +, Pb2 +, Zn2+) on five species of barks (Sweet chestnut, Oak, Douglas fir, Norway spruce, Scots pine species) were studied. The experimental data fitted well the Langmuir model, which allowed the expression of the mathematical parameters (qmax, maximum binding capacity; b, affinity). The qmax values increased conversely to the b values. The correlation of these mathematical values (qmax and b) with the analysis of the chemical composition of barks led us to note that Cu2 + interacts preferentially with phenolic groups present in lignins and tannins and, opposite in, Pb2 + with the carboxylic acid groups in polysaccharides. These observations were explained (i) quantitatively by the amount of different types of sites and (ii) qualitatively, by the physicochemical characteristics of cations, the nature and the tridimensional structure of adsorption sites. Finally, the results allowed to define the nature of the chemical interaction (monodentate or multidentate complex) between each specified chemical component of barks and each kind of heavy metal cations.

International audience; Agricultural wastes such as olive pomace and barley bran have been transformed in plastic by esterification with fatty acid chlorides after acidic or alkaline delignification. These esterifications were carried out in homogenous solution DMA/LiCl by classical heating or microwave activation. The plastics obtained were characterized by IR and NMR spectra, and tested for their mechanical properties and potentiality of biodegradation. The mechanical properties were improved by olefin metathesis of undecylenic ester from olive cellulose. delignification.

In this preliminary study, inulin, a fructooligosaccharide extracted from chicory roots, was converted into plastic films by acylation in homogeneous media and under conventional heating, using methacryloyl and lauroyl chlorides as acylating reagents and N,N-dimethyl-4-aminopyridine as basic catalyst. Products were analyzed by FT-IR and 1H NMR spectroscopies to confirm their structures. A preliminary study of their thermal properties was also achieved.

Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of Pb2+ from aqueous solutions was investigated. We developed a new solvent‐free approach to enhance the natural properties of bark by utilizing polyfunctional groups covalently attached at their surface. The hydroxyl groups of their polysaccharide moiety were functionalized by periodate oxidation and derivatized via reductive amination in presence of aspartic acid or 4,4′‐diamino‐2,2′‐stilbene disulfonic acid. The degree of substitution of derivatized bark was estimated by the means of pH titration. Adsorption isotherms of Pb2+ on derivatized barks were determined and compared with the performances of crude bark. Adsorption was characterized using the noncompetitive Langmuir adsorption model in terms of affinity (b) and maximum binding capacities (q max). Derivatization resulted in enhancements of both q max (×4–7) and b (×1.5–10). These experimental data are discussed in the context of the Hard and Soft Acid ...

This work deals with the synthesis of cellulosic plastic films obtained in homogeneous conditions by microwave-induced acylation of commercial or chestnut tree sawdust cellulose by fatty acids. The acylation reaction was studied according to N,N-dimethyl-4-aminopyridine (DMAP) amount, DMAP simultaneously playing the role of catalyst and proton trapping base. This study clearly showed that DMAP does not influence degrees of substitution (DS), massic, and molar yields. Plastic films synthesized in the absence of DMAP showed a decrease in mechanical behavior. Organic (tributylamine) or inorganic bases (CaCO3, Na2CO3) were then added to replace DMAP basic activity, and no changes were observed. Concerning thermal and mechanical properties of plastics obtained with various bases, glass transition temperatures (Tg) and degradation temperature (Td) were found constant whatever the base, and the best mechanical properties were obtained for films synthesized in the presence of CaCO3. The same remarks were made concerning the valorization of chestnut tree sawdust cellulose. Microbial biodegradation of plastic films with DS = 2.2 led to a loss of their mechanical behaviors. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1266–1278, 2005

Microwave-induced esterification of cellulose in homogeneous phase has been investigated. Cellulose was first solubilized in the solvent system LiCl/N,N-dimethylacetamide and then esterified by lauroyl chloride in the presence of N,N-dimethyl-4-aminopyridine. Microwave activation resulted in a drastic reduction of reaction time (1 min) compared to conventional heating. The mechanical and thermal properties of the plastic films obtained were established and a preliminary study of their biodegradability has been performed. To cite this article: C. Satge et al., C. R. Chimie 7 (2004).

New crosslinked cellulose-based plastic films were synthesized with olefin metathesis as a crosslinking reaction. Microcrystalline cellulose was first dissolved in a lithium chloride/N,N-dimethylacetamide solvent system and acylated by w-undecenoyl chloride under microwave irradiation with N,N-dimethyl-4-aminopyridine as the catalyst. Cellulose unsaturated fatty acyl esters with a degree of substitution (DS) ranging from 1.4 to 2.0 were then crosslinked by olefin metathesis with a first generation Grubbs catalyst. Crosslinking ratios (T) ranging from 20 to 90% were obtained for low catalyst amounts (

New crosslinked microcrystalline cellulose plastic films were made by olefin metathesis. Cellulose was first acylated under microwave irradiation by 10‐undecenoyl chloride in lithium chloride/N,N‐d...

The aim of this work is the esterification of cellulose with long chain acyl chloride in homogeneous media induced by microwave irradiation. The system used was cellulose/lauroyl chloride/ N , N -dimethylacetamide/LiCl and N , N -dimethylaminopyridine as a catalyst. The use of microwave resulted in a dramatic drop in reaction time: 1 min irradiation was sufficient, compared with 30 min to 2 days, when conventional heating is used. We studied the degrees of substitution (DS), weight increase and molar yields in function of lauroyl chloride and N , N -dimethyl-4-aminopyridine amounts. We also determined mechanical and thermal properties of a sample with DS=2.4 and the biodegradability for samples with DS ranging from 0.7 to 2.6.

The kinetic study of tetratolylporphyrin metallation by copper II ions in the presence of lithium salts was undertaken in an aprotic solvent. A catalytic effect of Li+ has been observed leading to a great enhancement (× 500 at 30 °C) in the rate of incorporation of Cu2+.

The aim of this work is the synthesis of a new family of glycosylated porphyrins in which the sugar moieties are linked to the tetrapyrrole ring by a thioglycosidic bond. Two series have been designed. The first one corresponds to meso-aryl porphyrin derivatives. The second one has been obtained from protoporphyrin IX derivatization. Aryl-porphyrins were prepared from tristolyl o- and p-hydroxyporphyrins followed by bromoallylation and thioglycosylation with peracetylated S-glucose, mannose and galactose and deprotection. The other series has been synthesized from protoporphyrin IX dimethylester with a regioselective glycosylation of terminal alkenyl carbon. The UV-visible, NMR and MALDI mass spectra are presented. Photocytotoxicities of the synthesized compounds against K562 chronic leukaemia cell line has been evaluated.

The synthesis of a polycyclic heterocyclic ring system compound, ethyl 7-hydroxy-4-oxo-2-phenyl-4,5-dihydro-3H-benzo[6,7]cyclohepta[1,2-d]pyrimidine-6-carboxylate was carried out by condensation of benzamidine on diethyl 5,9-dihydroxy-7H-benzo[a]cycloheptene-6,8-dicarboxylate, after opening and then closure of the seven membered ring.

Cellulose-enriched residues from maize bran can be transformed into plastic films after esterification of the cellulose by various fatty acid chlorides. Alkali pretreatment and acidic activation of the sample are necessary before the esterification reaction in order to form esters. The degradation by microorganisms of the plastic film was also studied. We showed that the isolated strain (chromobacterium violaceum) can hydrolyze modified cellulose plastic films. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3040–3045, 1999

Cellulose-enriched residues from wheat bran can be transformed in bioplastics after esterification of the cellulose by lauroyl chloride. Before the esterification reaction, an activation step with a swelling of the sample in dilute acid and subsequent drying was required. This activation had a marked influence on the amount of esterified product and its degree of substitution. Using pure cellulose as well as cellulose-enriched agricultural residues, we have shown that the cellulose was totally recovered after this pretreatment and that partial hydrolysis of cellulose chains occurred during the drying step, which probably improved the accessibility to chemical reagents. The possible role of sulfuric acid as catalyst for the esterification reaction of the cellulose by lauroyl chloride was discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1933–1940, 1999

In this paper, we present the synthesis of two glycosylated strapped porphyrins. Structural elucidation is described ( 1 H NMR, MS Maldi and UV visible). The photocytotoxicity of these glycosyl strapped porphyrins against carcinogenic K562 cells is compared to hematoporphyrin as reference.

— Photodynamic treatment of promyelocytic K562 cells in the presence of a monoglucosylporphyrin or hematoporphyrin leads to a sequence of events recognized as hallmarks of apoptosis: a drop in mitochondrial potential, concurrent with a drop in ATP level and a decrease in cell respiration, translocation of phosphatidylserine of the plasma membrane, DNA fragmentation, appearance of apoptotic bodies and eventually loss of plasma membrane integrity. The chronology of these events is in accordance with sequential events induced by other known proapoptotic agents; in contrast to these agents that induce apoptosis in a restricted part of the cell population, we observed that the entire cell population (apart from a small percentage of cells that endured rapid necrosis during phototreatment) underwent apoptosis after irradiation in the presence of porphyrins. It appears that photodynamic treatment allows the bypass of early apoptotic signals in K562 cells that are otherwise renowned for their resistance to drug-induced apoptosis (A. McGahon, R. Bissonnette, M. Schmitt, K. M. Cotter, D. R. Green and T. G. Cotter, Blood 83, 1179–1187, 1994). Singlet oxygen is believed to be the proximate reactive species generated by porphyrin illumination. Because this molecule reacts with almost every cellular constituent, the way that singlet oxygen or its reactive oxygen species byproducts trigger apoptosis remains to be elucidated.

A series of neutral meso-arylglycosylporphyrins has been tested in order to evaluate their potency as antifungal agents against the yeast Saccharomyces cerevisiae. Photodynamic activity of these molecules results in intracellular damage as evidenced by the loss of clonogenicity and DNA fragmentation. The ability of these photosensitizers to permeate yeast cells is determined by microspectrofluorimetry and is correlated with their antifungal potency. Amphiphilic porphyrin derivatives are shown to exhibit the more pronounced photoactivity.

A new class of porphyrins bearing thioglycosyl groups is presented in order to improve targeting of malignant cells and resistance to glycosidases. These compounds were synthesized in four steps. They produced 1 O 2 and their photocytotoxicity against the yeast Saccharomyces cerevisiae was compared with the effect of haematoporphyrin.

The synthesis of a series of pyrazine analogues of the anti-herpes compound, acyclovir is described. These syntheses were accomplished by various methods: in the presence of a Lewis acid or NaH for hydroxyethoxymethyl and hydroxybutyl groups or by sequential oxidation/reduction of l-β-D-ribofuranosyl)-2-pyrazinones for 2′,3′-acyclonucleosides. Antiviral (HSV-1, CMV, Cox B4, HIV-1) properties of these compounds were determined.

Two agricultural by-products, sugar-beet pulp and wheat bran, have been examined for their suitability to be transformed into bioplastics by esterification by lauroyl chloride. Influence of cellulose content was studied on eleven samples enriched in cellulose after chemical or enzymatic removal of pectins from sugar-beet pulp and heteroxylans from wheat bran. After a pretreatment by immersion in 0.5 mol/L sulfuric acid, esterification was carried out with lauroyl chloride. Neither the amount of cellulose nor the extraction treatment had a marked influence on the formation of plastic. A film could be obtained from all the wheat-bran samples, including samples with low cellulose content, but only from one sugar-beet pulp sample. The crystallinity of the cellulose in sugar-beet pulp and wheat bran were different. The nature of cellulose could be responsible for the failure of sugar-beet pulp residues to form plastic.

International audience; We describe a sensing system that relies upon the formation of specific complexes between uranyl ion and bisphosphonate-capped gold nanoparticles. The ensuing concentration-dependent red-shift of surface plasmon resonance absorption allows the determination of uranyl ion concentration within the 1.5-15 ppm range.

A stereoselective synthesis of β-thymidine using 2-deoxy- D -erythro-pentofuranosyl-trichloroacetimidate as the activating group is reported. This five-step route includes only one chromatographic purification with an overall yield of 30% in β-thymidine and stereoselectivity of approximately 80%.

A moderate yield (55%) preparation of N-1 substituted thymine has been achieved by reacting an excess of 4-bromobutylacetate at 100 °C for 48 hrs. N-1, N-3 bisalkylated and O-alkylated compounds were also obtained as by-products. © 1997 Published by Elsevier Science Ltd.

Piperazinone nucleosides can be formed by N-glycosylation with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose of either piperazin-2-ones or pyrazin-2-ones followed by reduction of the heterocycle with rhodium on alumina. All the prepared compounds were tested for their activity against the Visna virus, but did not show significant antiviral activity.

Trisalkylpyridinium porphyrins substituted by one glycosyl (glucosyl, maltosyl, and lactosyl) moiety have been prepared in acceptable yields. These glycosylated cationic porphyrins have been synthesized from pyrrole condensed with 4-pyridinecarboxaldehyde, and suitable ortho- or para peracetylglycosyloxybenzaldehyde derivatives in refluxing propionic acid –Ac2O followed by action of alkyliodide in DMF. Deprotection of the glycosylated moieties led to a new class of representative glycosylated porphyrins. Key words: porphyrins, cationic, glycosylated; phototherapy, cancer.

Various 5-alkyl-6-aza-5,6-dihydrouridines and 6-(β-D-ribopyranosyl)-5-alkyl-6-aza-5,6-dihydrouracils have been synthesized. A new regioselective method is described for coupling triazinic bases to the sugar unit. Different epimers were isolated. Antiretroviral activity against Visna virus was evaluated.