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The aim of this study was to determine the combined effect of fermentation parameters and enhance the production of cellular biomass and antibacterial compounds from Paludifilum halophilum SMBg3 using the response surface methodology (RSM). Eight variables were screened to assess the effects of fermentation parameters on growth and metabolite production by Taguchi experimental design. Among these, the initial pH, temperature, and the percentage of MgSO4·7H2O in the medium were found to be most influential. The Box–Behnken design was applied to derive a statistical model for the optimization of these three fermentation parameters. The optimal parameters were initial pH: 8.3, temperature growth: 44°C, and MgSO4·7H2O: 1.6%, respectively. The maximum yield of biomass and metabolite production were, respectively, 11 mg/mL dry weight and 15.5 mm inhibition zone diameter against Salmonella enterica, which were in agreement with predicted values. The bioactive compounds were separated by the thick-layer chromatography technique and analyzed by GC/MS, NMR (1D and 2D), and Fourier-transform infrared spectroscopy (FT-IR). In addition to several fatty acids, N-(1-carboxy-ethyl)-phthalamic acid was identified as the main antibacterial compound. This element exhibited a potent activity against the ciprofloxacin-resistant Salmonella enterica CIP 8039 and Pseudomonas aeruginosa ATCC 9027 with a minimum inhibitory concentration (MIC) value range of 12.5–25 μg/mL. Results demonstrated that P. halophilum strain SMBg3 is a promising resource for novel antibacterial production due to its high-level yield potential and the capacity for large-scale fermentation.

The aim of this study was to determine the combined effect of fermentation parameters and enhance the production of cellular biomass and antibacterial compounds from Paludifilum halophilum SMBg3 using the response surface methodology (RSM). Eight variables were screened to assess the effects of fermentation parameters on growth and metabolite production by Taguchi experimental design. Among these, the initial pH, temperature, and the percentage of MgSO4·7H2O in the medium were found to be most influential. The Box–Behnken design was applied to derive a statistical model for the optimization of these three fermentation parameters. The optimal parameters were initial pH: 8.3, temperature growth: 44°C, and MgSO4·7H2O: 1.6%, respectively. The maximum yield of biomass and metabolite production were, respectively, 11 mg/mL dry weight and 15.5 mm inhibition zone diameter against Salmonella enterica, which were in agreement with predicted values. The bioactive compounds were separated by the thick-layer chromatography technique and analyzed by GC/MS, NMR (1D and 2D), and Fourier-transform infrared spectroscopy (FT-IR). In addition to several fatty acids, N-(1-carboxy-ethyl)-phthalamic acid was identified as the main antibacterial compound. This element exhibited a potent activity against the ciprofloxacin-resistant Salmonella enterica CIP 8039 and Pseudomonas aeruginosa ATCC 9027 with a minimum inhibitory concentration (MIC) value range of 12.5–25 μg/mL. Results demonstrated that P. halophilum strain SMBg3 is a promising resource for novel antibacterial production due to its high-level yield potential and the capacity for large-scale fermentation.

International audience; The aim of this work was to investigate the impact of almond gum as coating agent to decrease the oil absorption and to increase the moisture content of fried potato chips meaning a Box–Behnken design. The studied parameters were: almond gum concentration (0–20 g/L), frying time (30–120 s) and frying temperature (160–190 °C). Results showed that the increase of almond gum concentration up to 20 g/L decreased the oil uptake of potato chips by 34% and increased the moisture by 29.5%. Optimal coating and frying conditions found with RSM were thus achieved with 20 g/L aqueous almond gum, 75 s frying time at 160 °C frying temperature. Additionally, the study of sensorial analysis (color, appearance, crispiness, taste, odor, appetence) showed that the chips coated with almond gum have an overall acceptability better than the uncoated potato chips, and the ones coated with arabic gum. The textural analysis of potato chips showed that the hardness (rigidity) decreased significantly by coating either with almond gum or arabic gum. The results obtained through this work showed that coating with almond gum improves the sensorial and nutritional qualities of potato chips.

The present paper aimed to characterize and treat a landfill leachate using a coagulation–flocculation process. The leachate was obtained from a landfill in the city of Sousse, Tunisia. Its physicochemical characterization showed high levels of chemical oxygen demand (COD), ammonium, and heavy metal contents. The coagulation–flocculation process was applied as pretreatment effluent to reduce these pollutants. The key operating parameters (pH, coagulant dose, flocculant dose, and mixing speed in the flocculation step) on the coagulation–flocculation process were optimized using response surface methodology to investigate COD removal in landfill leachate. In this regard, a hybrid design was carried out to seek optimal conditions which were as follows: pH: 3.36; concentration of coagulant: 0.87 g/l; concentration of flocculant: 26 mg/l; and mixing speed: 48 rpm. These conditions have been proved experimentally.

The aim of this paper was to optimize extraction conditions of C. cardunculus rennet by response surface methodology, in order to maximize its milk-clotting activity (MCA). The second objective was to examine the effect of different amounts of the optimized extract and the type of milk, on technological characteristics of the obtained gels. Results of the central composite design showed that the optimum extraction conditions, corresponding to maximum MCA (9.550CAU/mL), were selected as follows: Grinding time 30s, pH 3, extraction time 50min and solid to liquid ratio 15g/100mL. According to technological properties, it can be concluded that C. cardunculus extract exhibited an excellent efficiency on raw milk, in term of dynamic moduli and gel firmness, as compared to chymosin. A good gelation time and WHC were also obtained. Consequently, the optimized C. cardunculus rennet has the potential to be employed as an efficient milk-clotting agent.

Chitosan is obtained by deacetylation of chitin. Chitosan versatility is directly related to the polymer's characteristics depending on the deacetylation process. The aim of this research was to study the parameters influencing deacetylation and to elucidate their effect on acetylation degree (DA) and molecular weight (MW). The effect on chitosan DA was investigated using a fractional factorial design 2 7−3 with seven factors and two variation levels. The tested factors were: X 1 = number of successive baths, X 2 = reaction time, X 3 = temperature, X 4 = alkali reagent, X 5 = sodium borohydride, X 6 = the atmospheric conditions and X 7 = alkali concentration. A mathematical model was investigated corresponding to the following relation ŷ = 7.469 − 1.344 X 1 − 1.094 X 2 − 3.094 X 3 + 1.906 X 4 + 0.656 X 5 + 0.906 X 6 − 1.031 X 7 + 0.469 X 1 X 2 − 0.781 X 3 X 4 + 0.906 X 1 X 3 X 4 with R 2 = 0.99. This model allows fixing experimental conditions for each desired DA. To study the effect on chitosan MW, only atmospheric conditions and use of sodium borohydride as an oxygen scavenger were investigated. The use of sodium borohydride and nitrogen atmosphere was found to have a protective effect against chitosan degradation during deacetylation.

The chemical composition of essential oils obtained by hydrodistillation from Tunisian wild growing myrtle ripe fruits, leaves and floral buds was examined by GC and GC-MS. The yields of hydrodistilled oils obtained from different plant parts were: leaves 0.5%, floral buds 0.2% and ripe fruits 0.02%. Significant differences were found in the concentration of main constituents of the oils: α-pinene [48.9% (floral buds), 34.3% (fruits), 23.7% (leaves)], 1,8-cineole [15.3% (floral buds), 26.6% (fruits), 61.0% (leaves)]. The leaves oil contained less linalool than floral buds and ripe fruits oils. Tunisian myrtle is characterized by the absence of myrtenyl acetate.

In the present study, betalains content, phenolic composition, and antioxidant activity of different parts of red beet (Beta vulgaris L. conditiva) (i.e., roots and stems) were compared. Crude extract of root showed the highest betalain content with a maximum of 53 ± 4 mg betanin eq and 46 ± 3 mg vulgaxantin I eq g−1 of extract stems showed higher total phenolic concentration than roots, ranging between 2.0 ± 0.4 and 14.6 ± 0.5 mg gallic acid eq−1 of extract. Chemical composition was analyzed using LC-MS. Betalains (vulgaxanthin I, betanin, and isobetanin) and phenolics (gallic acid, ferulic acid, chlorogenic acid, caffeic acid, vanillic acid, syringic acid, ellagic acid myricetin, quercetin, rutin, kampferol) were identified in roots and stems. Betalain extract obtained from roots showed higher antioxidant activity than extract obtained from stems.

International audience; The chemical composition of Cyperus rotundus L. tubers essential oil from the South of Tunisia was analyzed using GC-FID and GC-MS. Fifty compounds were identified representing 84.6 % of the total oil. A new chemotype was found in Tunisia. This essential oil was characterized by sesquiterpenes abundance (78.3 %) mainly represented by cyperene (15.2 %) and cyperotundone (19.7 %). The essential oil (EO) was further fractionated into three fractions (F1: n-pentane, F2: n-pentane/diethyl ether (95/5) and F3: diethyl ether). The antioxidant activity of the EO and its fractions was tested using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test and beta-carotene bleaching method. Results showed that the whole EO was more active than the fractions with an effective concentration (EC50) of 0.85 +/- 0.03 mg/mL and an antioxidant activity coefficient (AAC) of 396.0 +/- 2.4. The antimicrobial activity of the EO and its fractions was evaluated using the disc diffusion method against six foodborne pathogens and results showed that Staphylococcus aureus was the most inhibited bacterium with an inhibition diameter of 15.2 +/- 0.8 mm for the whole EO.

International audience; This work describes the feasibility of using almond shell as feedstock for bioethanol production. A pre-treatment step was carried out using 4% NaOH for 60 min at 121 °C followed by 1% sulfuric acid for 60 min at 121 °C. Enzymatic saccharification of the pre-treated almond shell was performed using Penicillium occitanis enzymes. The process was optimized using a hybrid design with four parameters including the incubation time, temperature, enzyme loads, and polyethylene glycol (PEG) concentration. The optimum hydrolysis conditions led to a sugar yield of 13.5%. A detoxification step of the enzymatic hydrolysate was carried out at pH 5 using 1 U/ml of laccase enzyme produced by Polyporus ciliatus. Fermenting efficiency of the hydrolysates was greatly improved by laccase treatment, increasing the ethanol yield from 30% to 84%. These results demonstrated the efficiency of using almond shell as a promising source for bioethanol production.

Different crude microbial proteases were applied for chitin extraction from shrimp shells. A Box–Behnken design with three variables and three levels was applied in order to approach the prediction of optimal enzyme/substrate ratio, temperature and incubation time on the deproteinization degree with Bacillus mojavensis A21 crude protease. These optimal conditions were: an enzyme/substrate ratio of 7.75 U/mg, a temperature of 60 °C and an incubation time of 6 h allowing to predict 94 ± 4% deproteinization. Experimentally, in these optimized conditions, a deproteinization degree of 88 ± 5% was obtained in good agreement with the prediction and larger than values generally given in literature. The deproteinized shells were then demineralized to obtain chitin which was converted to chitosan by deacetylation and its antibacterial activity against different bacteria was investigated. Results showed that chitosan dissolved at 50 mg/ml markedly inhibited the growth of most Gram-negative and Gram-positive bacteria tested.

The β,β′-dihydroxydithioethers, derived from oxirane, have been converted into dithioethers dithiols in good yields. A colloidal solution of gold nanoparticles (AuNPs) with 5,8-dithiadodecane-3,10-dithiol was prepared and showed a good stability from tight binding offered by the thiol group on the Au surfaces.

Epoxides represent an important class of compounds in organic synthesis. For instance, their nucleophilic opening leads to a large number of 1,2-difunctionalized systems 1–6. Their reactions with d...

The essential oil of Mytrus communis L. floral buds from Tunisia was analyzed by GC and GC/MS. Thirty-seven compounds were identified, representing 98.7% of the total oil. The major constituents were described as α-pinene (48.9%) and 1,8-cineole (15.3%). The antioxidant activity of the obtained essential oil was investigated by means of β-carotene bleaching (BCB) test and free radical scavenging assay using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). Results showed that Myrtus communis L. floral buds essential oil has a significant antioxidant effect when tested by each method respectively. The strong antioxidant activity of the studied oil can be attributed to the high content in hydrocarbon monoterpenes and oxygenated monoterpenes.

The ability of a non-commercial immobilized Staphylococcus xylosus lipase to catalyze the esterification of propanol with gallic acid was investigated and the antioxidant as well as the antimicrobial activities of the ester formed were evaluated. The response surface methodology, based on a three variables Box–Behnken design (reaction temperature, enzyme amount and 1-propanol/gallic acid molar ratio), was used to optimize the experimental conditions of propylgallate synthesis. The maximum conversion yield (90% ±3.5) was obtained by using 400 IU of immobilized lipase and a propanol/gallic acid at a molar ratio of 160 at 52 ◦ C. The obtained ester was characterized by spectroscopic methods, NMR and FTIR. The antioxidant activity of propyl gallate was evaluated and compared to the synthetic classical antioxidants, BHA and ascorbic acid, taken as references. In addition, the antimicrobial activity of the propyl gallate was tested against S. xylosus, Escherchia coli and Staphylococcus aureus using disc diffusion and macrodilution methods. Our results show that the synthesized propyl gallate ester presents a higher antioxidant and antimicrobial power than the parent gallic acid as well as the synthetic classical antioxidants. © 2010 Elsevier B.V. All rights reserved.

Acid catalysed condensation of F -alkyl α-hydroxy acids with simple aldehydes or ketones gave F -alkyl 1,3-dioxolan-4-ones. When BF 3 ,OEt 2 was used as the catalyst, the condensation products were obtained in moderate to good yields and the “cis” isomers are largely favoured, while with HOTs/H 2 SO 4 as catalyst, poor yields and lower stereoselectivities were observed.

In a previous paper, we showed that the preparation of sulfated diethanolamide of fatty acids is easy to carry out without organic solvents when using olive pomace oil as starting material; the reaction yield was, however, highly variable as a function of factor levels. The purpose of this research is to look for the optimal experimental conditions. We started by applying a supersaturated experimental design to screen for important factors among a list of 31 potentially influential factors in 18 experiments. Thus, we constructed a two-level supersaturated design as a half fraction of a 36-experiment Hadamard matrix and used it for this screening purpose. Multiple regression methods namely stepwise selection procedure, ridge regression and all-subset regressions were used to analyze the supersaturated design results according to a four step procedure. Results indicated that six factors, namely, molar ratio SO 3 /ester, amidation time, amide addition rate, alkali reagent, alkali concentration, and amidation temperature, were very influential factors. Three other factors were moderately influential: neutralization temperature, sodium methanoate amount, and methanol amount. In future research, these factors will be further studied in order to perform robustness tests of the process.

BACKGROUND: The agro-industries generate thousands of tons of by-products, such as bran or pulps, each year. They are, at best, used for cattle feeding. Through biocracking, this biomass may constitute a renewable source for various molecules of interest for the industry. For instance, ferulic acid, a compound showing antioxidant ability, is found in abundance in cereal bran. Its release depends mainly on the breaking of its ester linkage to other constitutive elements of the cell wall, such as arabinoxylans. Response surface methodology was used to evaluate the effects of ferulic acid esterase (FAE) and xylanase activities, as well as incubation time and temperature, on ferulic acid extraction yield from wheat bran. Under optimized conditions, the composition of the hydrolysate and of residual bran were compared to native bran. RESULTS: Experiments carried out under the predicted optimal conditions (FAE amount, 27 U g−1; xylanase amount, 304 U g−1; incubation time, 2 h; and temperature, 65 °C) led to an extraction yield of 52.8%, agreeing with the expected value (51.0%). The crude ferulic acid fraction was purified with Amberlite XAD16, leading to a final concentration of 125 µg mL−1 of ferulic acid in ethanol. The antioxidant capacity of this purified fraction was evaluated by the DPPH· scavenging method: it exhibited better efficiency (EC50 = 10.6 µmol L−1 in ferulic acid) than the ferulic acid standard (EC50 = 13.7 µmol L−1). CONCLUSION: These results confirm the potential of wheat bran valorization in the field of natural antioxidant extraction, possibly viable in an industrial scheme. Copyright © 2009 Society of Chemical Industry

The sequential simplex method and its derivatives, the modified and the super modified simplex methods, are used to optimize on-line the levels of the parameters of an injection moulding process (producing bottle caps) in order to minimize the process cycle time and to reduce the rejects. Nine process parameters are selected to conduct the optimization: screw rotation speed, back pressure, injection rate, injection pressure, cooling time, holding pressure, holding time, nozzle temperature and opening stroke. Optimum conditions are achieved using 17 experiments only. The obtained results clearly show that the process cycle time is very sensitive to the effect of two parameters: cooling time and holding pressure. Low levels of these two parameters are needed in order to minimize cycle time. In addition, the evaluation of rejects in the course of the simplex evolution shows that this additional response is also sensitive to the same parameters. In order to minimize rejects, these two parameters have to be set to low levels. Finally, this study allows us to conclude that the simplex method may be easily used and reused on-line to drive the process continuously towards its optimal conditions without any disruption of production or additional operating costs.

Response surface methodology was used to optimize pectin recovery from lemon by-product using an acidified date juice as extraction solution. When enriched in pectin, this latter can be useful for preparation of date-lemon jelly. The effects of three parameters namely temperature, pH and extraction time, on pectin extraction were studied. The fitted mathematical model allowed us to plot response surfaces as well as isoresponse curves and to determine optimal extraction conditions. Results clearly indicated that the temperature was the main factor influencing the pectin yield which increased with temperature and time or decreasing pH. The selected optimal conditions were: temperature 84.34 °C; extraction time 3 h 34 min and pH 2.8. These conditions yielded about 11.21% of pectin versus 10.89% for the predicted value.

Sulfated diethanolamides of fatty acids are known to be effective lime soap dispersing agents. However, their preparation from fatty acids via fatty amides requires the use of organic solvents due to the high viscosity of both fatty amides and sulfated fatty amides. This study shows that the preparation of sulfated fatty amides is relatively easy when using olive pomace oil as the raw material. The latter, is converted into sulfated fatty amides by performing the following steps: saponification, hydrolysis, esterification, amidation, and sulfation. In the final step, the mixture obtained has sufficient fluidity, due to its high linoleic acid amide content, to obviate the use of organic solvents, as usually suggested in the literature. Characterization of the product was carried out by chemical analyses, FTIR, 13C NMR, GC, and HPLC. It was shown that the yield of the amidation reaction is about 80%, and that of the sulfation reaction can exceed 100% against the pure amide (more than one sulfate group could be linked to one amide molecule). On the other hand, the Borghetty test showed that the product is an effective dispersant with a lime soap dispersing power equal to five.

Chitin and derivatives used for biomedical or pharmaceutical applications require a high level of purity and quality that are difficult to achieve. In this study, we propose to optimize the extraction of chitin in order to obtain pure product keeping a structure as close as possible to the native form. Thus, demineralization step was firstly optimized using response surface methodology. In the optimized conditions predicted by the model, the obtained chitin has an acetylation degree (DA) and a demineralization degree (DM) equal to 99% and 100%, respectively. Then, different microbial and fish crude alkaline proteases were tested for their efficiency in deproteinization. Crude alkaline proteases giving the highest deproteinization degrees (DP), Bacillus mojavensis A21 and Scorpaena scrofa, were selected for chitin extraction. The obtained DP was 88±2% and 83±1%, respectively. At the end, effect of the use of mixed enzymatic treatment with the two selected crude enzymes and the order of demineralization/deproteinization steps were tested. The results demonstrated that two separated steps in enzymatic treatments realized on demineralized sample give the best DP (96%) preserving the DA (99%).

2-(F-alkyl) enol ethers react easily with thiols. With one equivalent of the thiol, the corresponding 2-(F-alkyl) thioenol ethers were formed via an addition-elimination mechanism. With two equivalents of thiol or with one equivalent of 1,2-ethanedithiol, 2-(F-alkyl) thioacetals or 2-(F-alkyl) dithiolanes were obtained in good yields.

The present research studies the optimization of the preparation of a hydrotrope (mixture of sodium toluenesulfonate and sodium xylenesulfonates) for liquid detergents using experimental designs. The preparation is carried out by selective sulfonation of toluene and xylene present in the BTX fraction of a natural gas. The optimization of five responses has been carried out in two steps. First, we carry out an asymmetrical screening design 2 1 3 6 //18 to select from seven factors, those factors which have significant influence on the amount of residual sodium sulfate in the product and on the total conversion of toluene and xylenes. Secondly, we carry out a Box–Behnken design to optimize three retained factors (temperature, molar ratio of acid to toluene plus xylenes, and the amount of desulfation agent), using response surface methodology. In addition, and in order to reach near-optimal sulfonation conditions, we use the desirability functions to optimize the five responses simultaneously. This allows us to determine for the whole process, sulfonation conditions leading to a high yield of toluene and xylene conversion and acceptable amounts of residual sodium sulfates and sodium benzenesulfonate.

The present research studies the formulation and optimization of a self-leveling composition for floor toppings. This formulation is, in particular, based on a fluoroanhydrite which is a by-product of a Tunisian plant for fluorhydric acid preparation; it also contains aggregates, a neutralizing agent, a hydration accelerator and, especially, a plasticizer prepared by sulfonation of the lignin extracted from the black liquor of a Tunisian esparto grass soda pulping process. The optimization of four responses (plasticity, compressive strength, initial and final setting times) has been carried out in two steps. First, we obtain a coarse composition with a relatively acceptable rheological properties. Second, we carry out a mixture design in the surroundings of the retained composition aimed at obtaining a product with the required characteristics formulated by the users of this kind of materials. To this end, the evolution of the plasticity and the setting times of the fresh mortar and the compressive strength of the hardened mortar in a four-component system with constraints were analyzed using a mathematically independent variable approach. Finally, and in order to reach a near-optimal composition, we use the desirability functions to optimize the four responses simultaneously. This allows us to determine the coordinates of a composition which is characterized by high plasticity, acceptable compressive strength and relatively rapid setting times.

A convenient preparation of vicinal perfluoroalkyl enol ethers, by the action of alcohols on 1-bromo-1-perfluoroalkylethylenes in the presence of potassium hydroxide, is described. Some aspects of their reactivity are reported.

The Tunisian blast-furnace slag has been characterized by several physicochemical methods to evaluate its hydraulic reactivity. It has been noted that nearly all the slag is glassy, so its use as a replacement of cement is possible. This result has been confirmed by different physical tests applied to blended cements as specific surface, normal consistency, setting time, stability to expansion and the minislump. Finally, a slag cement composition has been formulated and optimized using a mixture design. The optimized formula giving the maximum of compressive strength at 7 and 28 days was 61% clinker, 35% slag, 3% gypsum, and 1% limestone.

The objective of the work described in this first paper of a series is an investigation of the preparation of a sulfonated esparto grass lignin (SEL) and its behavior as a plasticizing–water-reducing agent for cement–water systems. SEL is prepared by extracting the lignin from the black liquor of a soda esparto grass pulping process and then sulfonating it with a mixture of sodium sulfite and formaldehyde. Analyses and characterization of SEL carried out with high-performance size exclusion chromatography (HPSEC), reversed phase chromatography (RPC), infrared spectrometry and chemical methods show that both the molecular weight average and the combined sulfur content are relatively high. Moreover, HPSEC shows that SEL has a relatively more uniform molecular weight distribution (MWD) than the commercial products obtained from the sulfite wood pulping process. On the other hand, SEL could reduce the water content, improve the workability and compressive strength of mortars. SEL also permits a very low rate of slump loss of cements without excessive extension of the final set time.

The essential oils from Thymus capitatus (L.) Hoffmgg. et Link, Ocimum basilicum (L.), Myrtus communis (M.) and Laurus nobilis (L.) have been characterized and tested against two bacteria (Lactobacillus plantarum and Escherichia coli) and a fungus (Geotrichum candidum), using a submerged broth culture method. The results obtained showed that T. capitatus and O. basilicum were the greatest inhibitors of all the strains tested, and that Escherichia coli was more inhibited than Lactobacillus plantarum by all the essential oils tested. Copyright ©2003 John Wiley & Sons, Ltd.

In a previous study, we presented a new method for preparing a mixture of sodium toluenesulfonates (STS), sodium xylenesulfonates (SXS), sodium benzenesulfonate (SBS) and Na 2 SO 4 by sulfonating the BTX fraction of a Tunisian natural gas. Such mixtures can be used as a hydrotrope agent for concentrated liquid detergents. In the present work, we performed a mixture design in order to study the effect of each of these four components on the clear point and the viscosity of a liquid detergent, and therefore, to determine the conditions allowing to improve the effectiveness of the hydrotrope. Twenty-eight combinations of the 4 components out of 51 candidate points are selected by the Nemrod-W software according to the D-optimal criterion to fit two polynomial models. The statistical study shows that the fitted models were adequate to describe the clear point and the viscosity responses. Optimal conditions allowing to lower the two responses are then looking for by examining the response surface both as a contour plot, and as three-dimensional surface plot and the response trace. We prove that Na 2 SO 4 exhibits a harmful negative effect, while SXS and STS exhibit, respectively, a strong and moderate positive effect on both clear point and viscosity responses. As expected, SBS has a harmful effect on the two responses but the magnitude of this effect is lesser than that predicted by the preliminary experiments carried out with SBS alone. This phenomenon is explained by the formation of heteroassociation between SBS, STS and SXS similar to what is found in surfactants. The effectiveness of the hydrotrope, obtained by sulfonation of the BTX fraction of the Tunisian natural gas, is really improved by removing sulfates either by adding lime to precipitate gypsum, or isopropanol to reduce the solubility of Na 2 SO 4 .

Action of zinc on F -alkylated β-bromoacids and esters allowed the preparation of the corresponding bromozincic derivatives which furnished: • The F -alkylated acids and esters (RCH 2 COOR) by hydrolysis. • The unsaturated acids and esters (R F ′CFCHCO 2 R) by heating at 110 °C.

The solvent-free reaction of oligoethylene glycol diglycidyl ethers with dimercaptoethane in the presence of benzyltrimethylammonium hydroxide (Triton B) gave, via regiospecific epoxide opening reactions, dihydroxy dithiacrown ethers in excellent yields and in short reaction times.

Diethylene glycol monochlorides were prepared from epoxides by action of the chloroethanol. Their conversion into substituted dithia-9-crown-3-ethers has been realized by treatment with p-toluenesulfonyl chloride, followed by the action of 1,2-dimercaptoethane.

A convenient method for the one-pot conversion of olefins into the corresponding enol thioethers is reported. The products were obtained via the N-bromosuccinimide cobromination reaction of olefins with thiols in basic medium. Steric hindrance present in the product alkenes may explain the stereochemistry observed.

F-alkyl α-hydroxy acids and F-alkyl α-bromo acids were prepared respectively by the nitric acid ring-opening oxidative reaction of F-alkyl oxiranes, and oxidation by chromic acid of F-alkyl bromohydrins. The synthesized acids were converted to the corresponding methyl esters which may prove to be useful in the synthesis of F-alkylated heterocycles.

International audience; The chemical composition of Salicornia herbacea L. a food plant belonging to Chenopodiaceae was investigated based on its mineral composition, proteins and carbohydrates contents. The phenolic composition analyzed by high performance liquid chromatography with diode array detection (HPLC-DAD) showed the presence of eight phenolic acids and eight flavonoids. The biological activities of the methanol extract were conducted on the antioxidant activity evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and β-carotene-linoleic acid bleaching test. The extract was an efficient radical scavenger (IC50 = 55.3 ± 2.7 μg/mL) and exhibited a moderate inhibition of lipid peroxidation of linoleic acid emulsion. Antibacterial activity determined by disc diffusion method against four Gram negative and two Gram positive bacteria, showed effects against all strains. Cytochrome P450s (CYPs) inhibitory activity studied for the first time was evaluated against three CYP isozymes namely CYP1A2, CYP3A4 and CYP2D6. The extract was a potent inhibitor against CYP2D6 (IC50 = 3.88 ± 0.02 μg/mL). Highlights Salicornia herbacea have a nutritional property as food plant due to its phytochemical composition. Its methanol extract showed several biologic activities. This extract exhibited antioxidant and antibacterial activities. It was also a potent inhibitor of cytochrome P450 CYP1A2, CYP3A4 and CYP2D6.

Chitin extraction from shrimp shells by biological treatment, using the Bacilli Bacillus pumilus A1, is a non-polluting method and offers the opportunity to preserve the exceptional qualities of chitin and its derivatives. However, the major disadvantage of the fermentative way is the low efficiency of demineralization and deproteinization. The aim of this study is to improve the yield of extraction which depends on many factors, such as the medium composition and the physical parameters. In order to look for the optimal conditions, a Plackett and Burman design was carried out to screen eight factors influencing the deproteinization and demineralization efficiencies. The four most influencing variables were then examined to achieve the optimization using a central composite design. The results obtained showed that the optimal conditions were: shrimp shell concentration of 70 g/l, glucose concentration of 50 g/l, pH of 5.0 incubated with 0.225 OD of B. pumilus A1 inoculum, at 35 °C and 150 rpm for 6 days in 500 ml flask containing 100 ml of working volume. These conditions led to 88% of demineralization and 94% of deproteinization. 13C CP/MAS NMR spectral analysis of the chitin prepared was carried out and was found to be similar to that of the commercial α-chitin.

The opening of A-dicyanoepoxides by pyridine polyhdrofluoride yields polymerisable 2-fluorocyanoformyls which may be kept intact when diluated in dichloromethane or ether. These intermediates react with nuclecophiles such as water, methanol or amines to give respectivly 2-fluoroacids, esters or amides.

The decyanation of α-cyano-β-fluoro-α-hydroxyesters is achieved, at room temperature, by action of Ni(OAc)2. The corresponding 3-fluoropyruvates are obtained in good yields.

Alkenes react in diethyl ether with N -bromosuccinimide (NBS) and dimercaptoethane to afford the corresponding β,β′-dibromodithioethers. Bromine and dimercaptoethane are added to the aliphatic terminal olefins in an anti-Markovnikov fashion.

γ,Δ ethylenic perfluoroalkyl ketones, described for the first time, were prepared through the Claisen rearrangement of allyl F-alkylated vinyl ethers.

International audience; Two methods (agar diffusion and broth microdilution) were used to assess the antibacterial activity of Origanum majorana L. oil of Tunisian origin against 10 bacteria. The results showed that this oil was active against all of the tested strains. The most susceptible were Escherichia coli, Streptococcus A, Shigella dysenteria and Salmonella enteritidis. The least susceptible one was Pseudomonas aeruginosa.

The action of dimercaptoethane on alkyl oxiranes in the presence of benzyltrimethylammonium hydroxide (Triton B) allows, via regiospecific opening reaction, the preparation of the corresponding β,β′-dihydroxy dithioethers in excellent yields.

Using the phase transfer catalysis technique, a series of fluorinated acetals has been prepared, in basic medium, by action of dicholromethane on 2-mononfluorinated alcohols or 1-F-alkyl 2-fluoroethanols. The identification of these new acetals has been achived by the study cf their 1H, 19F NMR and their mass spectra.

γ,Δ ethylenic perfluoroalkyl ketones, described for the first time, were prepared through the Claisen rearrangement of allyl F-alkylated vinyl ethers.