Rhamnolipids (RLs), glycolipids biosynthesized by the Pseudomonas and Burkholderia genera, are kn... more Rhamnolipids (RLs), glycolipids biosynthesized by the Pseudomonas and Burkholderia genera, are known to display various activities against a wide range of pathogens. Most previous studies on RLs focused on their direct antimicrobial activity, while only a few reports described the mechanisms by which RLs induce resistance against phytopathogens and the related fitness cost on plant physiology. Here, we combined transcriptomic and metabolomic approaches to unravel the mechanisms underlying RL-induced resistance in wheat against the hemibiotrophic fungus Zymoseptoria tritici, a major pathogen of this crop. Investigations were carried out by treating wheat plants with a bioinspired synthetic mono-RL with a 12-carbon fatty acid tail, dodecanoyl α/β-L-rhamnopyranoside (Rh-Est-C12), under both infectious and non-infectious conditions to examine its potential wheat defense-eliciting and priming bioactivities. Whereas, Rh-Est-C12 conferred to wheat a significant protection against Z. tritic...
A series of cellulose esters (CEs) were obtained by grafting aliphatic acid chlorides (carbon cha... more A series of cellulose esters (CEs) were obtained by grafting aliphatic acid chlorides (carbon chain length ranging from 8C to 18C) onto cellulose backbone, in a homogeneous lithium chloride/N,Ndimethylacetamide (LiCl/DMAc) medium. These CEs were characterized by FTIR and 1HNMR spectroscopies and were converted into films by casting. Then, they were submitted to thermal, mechanical, thermomechanical and structural analysis, using Differencial Scanning Calorimetry (DSC), uniaxial tensile tests, Dynamic Mechanical Thermal Analysis (DMTA) and XRay diffraction, respectively. The aim of this study was to establish a correlation between the evolution of such physical properties and the length of the aliphatic grafted side chain.
An experimental design was applied for the optimization of the extraction process of two preserva... more An experimental design was applied for the optimization of the extraction process of two preservatives, benzoic and sorbic acids (BA, SA), from food drinks. A simple, rapid, and reliable solid-phase extraction (SPE) method for the simultaneous extraction of these two preservatives and their determination by liquid chromatography with a diode array detector was considered. Box–Behnken design (BBD) was applied to both steps of the SPE process: (i) the sample percolation to ensure the retention of the totality of the acids by the silica-based C18 sorbent; (ii) the elution step to ensure desorption of the totality of the acids from the cartridge. Thus, the volume, pH, and flow rate of the sample, and the percentage of MeOH, volume, and flow rate of the elution solvent, were optimized. Sample volume and pH have a significant influence (p < 0.0001 and p = 0.0115) on the percolation yield. However, no effect was recorded for the flow rate (p > 0.05). Flow rate also has no significant...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Scientific research is being compelled to develop highly efficient and cost-effective energy-stor... more Scientific research is being compelled to develop highly efficient and cost-effective energy-storing devices such as supercapacitors (SCs). The practical use of SC devices is hindered by their low energy density and poor rate capability due to the binding agents in fabricating electrodes. Herein, we proposed flower-like highly open-structured binder-free ZnCo2O4 micro-flowers composed of nanosheets supported in nickel foam (ZnCoO@NF) with improved rate capability up to 91.8% when current varied from 2 to 20 A·g−1. The ZnCoO@NF electrode exhibited a superior specific capacitance of 1132 F·g−1 at 2 A·g−1 and revealed 99% cycling stability after 7000 cycles at a high current density of 20 A·g−1. The improved performance of the ZnCoO@NF electrode is attributed to the highly stable structure of the micro/nano-multiscale architecture, which provides both the high conduction of electrons and fast ionic transportation paths simultaneously.
Application of polymer-flooding systems in secondary and tertiary oil recovery represents a real ... more Application of polymer-flooding systems in secondary and tertiary oil recovery represents a real challenge for oil industry. In this work, our main objective is to explore possibilities of making use of xanthan-g-polyacrylamide for polymer flooding in a particular Devonian oilfield of medium salinity. The graft polymer was synthesized by using microwave-assisted graft copolymerization reaction of acrylamide on xanthan. The synthesized copolymer with optimized grafting parameters has been characterized by Infrared Spectroscopy and Thermal Analysis (DSC). Rheological analysis by steady shear and oscillatory flow experiments have been subsequently performed for xanthan and grafted xanthan under reservoir conditions. In steady shear, as expected the grafted polymer solutions flow as shear-thinning materials and apparent viscosity showed good fits with Cross’s model. The viscosity losses due to salinity or temperature are more controlled for the grafted xanthan compared to pristine xanth...
Edible films and coatings with good mechanical/physical properties are highly required for carryi... more Edible films and coatings with good mechanical/physical properties are highly required for carrying medical substances and food packaging. So, solvent-cast films of α- or β-chitosan filled with palygorskite, montmorillonite or geopolymer-containing material (GCM), were prepared, and the effects of their clay contents (up to 50 wt.%) on the mechanical/physical properties were assessed. The microstructure of the films was investigated using FT-IR spectroscopy, SEM and thermal analysis. The results showed that, except for the films composed of GCM and β-chitosan, the mechanical properties of the films with limited (up to 5 wt.%) to moderate (5–25 wt.%) amounts of fillers increased as a result of the attractive electrostatic forces formed between the fillers and chitosan functional groups (–NH3+, CH2OH and NHCOCH3). However, due to the occurrence of coarse aggregates, the strength of filler-rich films declined. The addition of fillers led to an increase in porosity and water absorption ...
Essential oils obtained by hydrodistillation of Montanoa quadrangularis leaves, flowers, and stem... more Essential oils obtained by hydrodistillation of Montanoa quadrangularis leaves, flowers, and stems were analyzed by GC and GC/MS techniques revealing myrcene, limonene, β-phellandrene, and sabinene among the main components. The aim of the present study was to evaluate the MDR modulator activity on human MDR1 gene transfected mouse lymphoma cell line and the antimicrobial activity on the essential oils obtained from different parts of the species under investigation. The results revealed that MQL caused a similar increase in the fluorescence activity of the cells at 0.02 μL/mL comparing to the Verapamil® value. The antimicrobial assay was carried out according to the disc diffusion method. Five different bacterial strains (Staphylococcus epidermidis, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli AG 100, and Escherichia coli AG100A) were treated with the essential oils and the zones of inhibition were determined on TSA plates and TSA agar plates supplemented with Tween ...
In this study, polyphenols have been extracted from solid residues and leaves of olive tree (Olea... more In this study, polyphenols have been extracted from solid residues and leaves of olive tree (Olea europaea L) in order to assess this vegetable biomass by evaluation of their capacity as a natural antioxidants. The anti-oxidative activity was tested by addition of these extracts on commercial olive oil samples. The olive oil stability has been measured by accelerated oxidation under a simulated storage conditions (60°C/15 days). The change in the oxidation state was followed by measuring of the free acidity, peroxide value (PV) and the specific extinction at 270 nm. The assessment of enriched oils showed that polyphenols from olive by-products play a key role in reducing of oxidative deterioration of the oil. The results suggest the introduction of olive leaves and solid residues extracts in food preparation, both during storage or heating food, for better preservation.
Steroidal alkaloids are secondary metabolites mainly isolated from species of Solanaceae and Lili... more Steroidal alkaloids are secondary metabolites mainly isolated from species of Solanaceae and Liliaceae families that occurs mostly as glycoalkaloids. α-chaconine, α-solanine, solamargine and solasonine are among the steroidal glycoalkaloids commonly isolated from Solanum species. A number of investigations have demonstrated that steroidal glycoalkaloids exhibit a variety of biological and pharmacological activities such as antitumor, teratogenic, antifungal, antiviral, among others. However, these are toxic to many organisms and are generally considered to be defensive allelochemicals. To date, over 200 alkaloids have been isolated from many Solanum species, all of these possess the C27 cholestane skeleton and have been divided into five structural types; solanidine, spirosolanes, solacongestidine, solanocapsine, and jurbidine. In this regard, the steroidal C27 solasodine type alkaloids are considered as significant target of synthetic derivatives and have been investigated for more...
Glycolipids, carbohydrate fatty esters or sugar esters are amphiphilic molecules containing hydro... more Glycolipids, carbohydrate fatty esters or sugar esters are amphiphilic molecules containing hydrophilic groups bonded to hydrophobic parent structures. Recently, glycolipids have shown their antimicrobial and antitumor capacities. Their surface activity properties have applications in the food, pharmaceutical and cosmetic industries. Sugar esters' building blocks can be obtained from natural resources and/or be transformed by biochemical pathways for uses as surfactants. Biosurfactants are non-ionic, nontoxic, biodegradable, tasteless, and odourless. The biocatalysis of these molecules involves sustainable, green, and safer methods. The advantages of producing biosurfactants from enzymatic catalysis are the energy economy, high selectivity, production of natural products, reduction of the use of fossil-based solvents and chloride compounds. This review presents the most recent studies concerning the evaluation of the impact of the main parameters and their levels influencing the enzymatic synthesis of glycolipids. Various enzyme catalysed synthetic methods were described. The parameters studied were temperature, reaction time, solvent system, type of biocatalyst, substrates molar ratio proportion and the nature of substrates. This review discusses the influence of different biocatalysts in the conversions of glycolipids; The reactivity from mono to polysaccharides and their interaction with fatty acids of different carbon chain lengths in the presence of specific enzymes; The effect of the solvent polarity, the use of multiple solvents, ionic liquids, supercritical CO 2 , and solvent-free media in sugar ester conversions; And the optimization of temperature and reaction time in different enzymatic systems.
The use of agricultural by-products in the building engineering realm has led to an increase in i... more The use of agricultural by-products in the building engineering realm has led to an increase in insulation characteristics of biobased materials and a decrease in environmental impact. The understanding of cell wall structure is possible by the study of interactions of chemical compounds, themselves determined by common techniques like Van Soest (VS). In this study, a global method is investigated to characterise the cell wall of hemp shiv. The cell wall molecules were, at first, isolated by fractionation of biomass and then analysed by physical and chemical analysis (Thermal Gravimetric Analysis, Elementary Analysis, Dynamic Sorption Vapor and Infra-Red). This global method is an experimental way to characterise plant cell wall molecules of fractions by Thermal Gravimetric Analysis following by a mathematical method to have a detailed estimation of the cell wall composition and the interactions between plant macromolecules. The analyzed hemp shiv presents proportions of 2.5 ± 0.6% ...
Total phenolic compounds (TPC) and the chlorogenic acids content of potato by-product extracts of... more Total phenolic compounds (TPC) and the chlorogenic acids content of potato by-product extracts of two hydro alcoholic solvents (methanol, ethanol) and two extraction methods (maceration and heating-assisted extraction) were studied. The content of TPC in the extracts was determined spectrometrically according to the Folin–Ciocalteu procedure and calculated as chlorogenic acid equivalents. Soluble phenolic acids, especially the chlorogenic acids, were performed by HPLC. The antioxidant activity of potato by-product extracts was determined by using the total oxygen radical absorbance capacity (ORAC) method. The highest content of TPC was found in raw and lyophilized red waters when using ethanol as a solvent around 57 mg/g fresh weight. Heating-assisted extraction enhances this quantitative increasing. At the given operating conditions, unpeeled potato samples exhibit a higher TPC than peeled ones, showing that TPC are accumulated in skin tissue. The greatest amount of chlorogenic aci...
The capability of some polymers, such as chitosan, to form low cost gels under mild conditions is... more The capability of some polymers, such as chitosan, to form low cost gels under mild conditions is of great application interest. Ionotropic gelation of chitosan has been used predominantly for the preparation of gel beads for biomedical application. Only in the last few years has the use of this method been extended to the fabrication of chitosan-based flat structures. Herein, after an initial analysis of the major applications of chitosan flat membranes and films and their usual methods of synthesis, the process of ionotropic gelation of chitosan and some recently proposed novel procedures for the synthesis of flat structures are presented.
The curcumin degradation represents a significant limitation for its applications. The stability ... more The curcumin degradation represents a significant limitation for its applications. The stability of free curcumin (FC) and immobilized curcumin in complex particles (ComPs) based on different polysaccharides was studied under the action of several factors. Ultraviolet-visible (UV-VIS) and Fourier-transform infrared (FTIR) spectroscopy proved the FC photodegradation and its role as a metal chelator: 82% of FC and between 26% and 39.79% of curcumin within the ComPs degraded after exposure for 28 days to natural light. The degradation half-life (t1/2) decreases for FC when the pH increases, from 6.8 h at pH = 3 to 2.1 h at pH = 9. For curcumin extracted from ComPs, t1/2 was constant (between 10 and 13 h) and depended on the sample’s composition. The total phenol (TPC) and total flavonoids (TFC) content values increased by 16% and 13%, respectively, for FC exposed to ultraviolet light at λ = 365 nm (UVA), whereas no significant change was observed for immobilized curcumin. Antioxidant a...
Carotenoids have been implicated in protection of the eye from light-mediated photo-toxicity caus... more Carotenoids have been implicated in protection of the eye from light-mediated photo-toxicity caused by free radicals. Under conditions of normal oxidative stress the carotenoids serve as protective antioxidants; however, when the oxidative stress exceeds the antioxidant capacity, carotenoids can be oxidized into numerous cleavage products. The determination and identification of oxidized carotenoids in biological samples remains a major challenge due to the small sample size and low stability of these compounds. We investigated the reaction of various zeaxanthin cleavage products with O-ethyl hydroxylamine to evaluate their levels in a biological sample. For this, a sensitive and specific electrospray tandem mass spectrometry (ESI-MS/MS) was developed, avoiding the classical lower sensitive and specific HPLC-UV and fluorescence absorption methods. Protonated molecules [M + H] + of carotenoids upon collision-induced dissociation produced a number of structurally characteristic product ions. A series of complicated clusters of product ions differing in 14 (CH 2)and 26 (C 2 H 2)Da was characteristic of the polyene chain of intact carotenoids. All carotenoid ethyl oximes of zeaxanthin cleavage products were characterized by the losses of 60 and 61 Da in their MS/MS spectra. Through the application of the LC/MS/MS method, we identified two oxime derivatives of 3-hydroxy-b-ionone and 3-hydroxy-14-apocarotenal with protonated molecules at m/z 252 and m/z 370 respectively, in a human eye sample.
The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is curre... more The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is currently the most devastating foliar disease on wheat crops worldwide. Here, we explored, for the first time, the ability of rhamnolipids (RLs) to control this pathogen, using a total of 19 RLs, including a natural RL mixture produced by Pseudomonas aeruginosa and 18 bioinspired RLs synthesized using green chemistry, as well as two related compounds (lauric acid and dodecanol). These compounds were assessed for in vitro antifungal effect, in planta defence elicitation (peroxidase and catalase enzyme activities), and protection efficacy on the wheat-Z. tritici pathosystem. Interestingly, a structure-activity relationship analysis revealed that synthetic RLs with a 12 carbon fatty acid tail were the most effective for all examined biological activities. This highlights the importance of the C12 chain in the bioactivity of RLs, likely by acting on the plasma membranes of both wheat and Z. triti...
Rhamnolipids (RLs), glycolipids biosynthesized by the Pseudomonas and Burkholderia genera, are kn... more Rhamnolipids (RLs), glycolipids biosynthesized by the Pseudomonas and Burkholderia genera, are known to display various activities against a wide range of pathogens. Most previous studies on RLs focused on their direct antimicrobial activity, while only a few reports described the mechanisms by which RLs induce resistance against phytopathogens and the related fitness cost on plant physiology. Here, we combined transcriptomic and metabolomic approaches to unravel the mechanisms underlying RL-induced resistance in wheat against the hemibiotrophic fungus Zymoseptoria tritici, a major pathogen of this crop. Investigations were carried out by treating wheat plants with a bioinspired synthetic mono-RL with a 12-carbon fatty acid tail, dodecanoyl α/β-L-rhamnopyranoside (Rh-Est-C12), under both infectious and non-infectious conditions to examine its potential wheat defense-eliciting and priming bioactivities. Whereas, Rh-Est-C12 conferred to wheat a significant protection against Z. tritic...
A series of cellulose esters (CEs) were obtained by grafting aliphatic acid chlorides (carbon cha... more A series of cellulose esters (CEs) were obtained by grafting aliphatic acid chlorides (carbon chain length ranging from 8C to 18C) onto cellulose backbone, in a homogeneous lithium chloride/N,Ndimethylacetamide (LiCl/DMAc) medium. These CEs were characterized by FTIR and 1HNMR spectroscopies and were converted into films by casting. Then, they were submitted to thermal, mechanical, thermomechanical and structural analysis, using Differencial Scanning Calorimetry (DSC), uniaxial tensile tests, Dynamic Mechanical Thermal Analysis (DMTA) and XRay diffraction, respectively. The aim of this study was to establish a correlation between the evolution of such physical properties and the length of the aliphatic grafted side chain.
An experimental design was applied for the optimization of the extraction process of two preserva... more An experimental design was applied for the optimization of the extraction process of two preservatives, benzoic and sorbic acids (BA, SA), from food drinks. A simple, rapid, and reliable solid-phase extraction (SPE) method for the simultaneous extraction of these two preservatives and their determination by liquid chromatography with a diode array detector was considered. Box–Behnken design (BBD) was applied to both steps of the SPE process: (i) the sample percolation to ensure the retention of the totality of the acids by the silica-based C18 sorbent; (ii) the elution step to ensure desorption of the totality of the acids from the cartridge. Thus, the volume, pH, and flow rate of the sample, and the percentage of MeOH, volume, and flow rate of the elution solvent, were optimized. Sample volume and pH have a significant influence (p < 0.0001 and p = 0.0115) on the percolation yield. However, no effect was recorded for the flow rate (p > 0.05). Flow rate also has no significant...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Scientific research is being compelled to develop highly efficient and cost-effective energy-stor... more Scientific research is being compelled to develop highly efficient and cost-effective energy-storing devices such as supercapacitors (SCs). The practical use of SC devices is hindered by their low energy density and poor rate capability due to the binding agents in fabricating electrodes. Herein, we proposed flower-like highly open-structured binder-free ZnCo2O4 micro-flowers composed of nanosheets supported in nickel foam (ZnCoO@NF) with improved rate capability up to 91.8% when current varied from 2 to 20 A·g−1. The ZnCoO@NF electrode exhibited a superior specific capacitance of 1132 F·g−1 at 2 A·g−1 and revealed 99% cycling stability after 7000 cycles at a high current density of 20 A·g−1. The improved performance of the ZnCoO@NF electrode is attributed to the highly stable structure of the micro/nano-multiscale architecture, which provides both the high conduction of electrons and fast ionic transportation paths simultaneously.
Application of polymer-flooding systems in secondary and tertiary oil recovery represents a real ... more Application of polymer-flooding systems in secondary and tertiary oil recovery represents a real challenge for oil industry. In this work, our main objective is to explore possibilities of making use of xanthan-g-polyacrylamide for polymer flooding in a particular Devonian oilfield of medium salinity. The graft polymer was synthesized by using microwave-assisted graft copolymerization reaction of acrylamide on xanthan. The synthesized copolymer with optimized grafting parameters has been characterized by Infrared Spectroscopy and Thermal Analysis (DSC). Rheological analysis by steady shear and oscillatory flow experiments have been subsequently performed for xanthan and grafted xanthan under reservoir conditions. In steady shear, as expected the grafted polymer solutions flow as shear-thinning materials and apparent viscosity showed good fits with Cross’s model. The viscosity losses due to salinity or temperature are more controlled for the grafted xanthan compared to pristine xanth...
Edible films and coatings with good mechanical/physical properties are highly required for carryi... more Edible films and coatings with good mechanical/physical properties are highly required for carrying medical substances and food packaging. So, solvent-cast films of α- or β-chitosan filled with palygorskite, montmorillonite or geopolymer-containing material (GCM), were prepared, and the effects of their clay contents (up to 50 wt.%) on the mechanical/physical properties were assessed. The microstructure of the films was investigated using FT-IR spectroscopy, SEM and thermal analysis. The results showed that, except for the films composed of GCM and β-chitosan, the mechanical properties of the films with limited (up to 5 wt.%) to moderate (5–25 wt.%) amounts of fillers increased as a result of the attractive electrostatic forces formed between the fillers and chitosan functional groups (–NH3+, CH2OH and NHCOCH3). However, due to the occurrence of coarse aggregates, the strength of filler-rich films declined. The addition of fillers led to an increase in porosity and water absorption ...
Essential oils obtained by hydrodistillation of Montanoa quadrangularis leaves, flowers, and stem... more Essential oils obtained by hydrodistillation of Montanoa quadrangularis leaves, flowers, and stems were analyzed by GC and GC/MS techniques revealing myrcene, limonene, β-phellandrene, and sabinene among the main components. The aim of the present study was to evaluate the MDR modulator activity on human MDR1 gene transfected mouse lymphoma cell line and the antimicrobial activity on the essential oils obtained from different parts of the species under investigation. The results revealed that MQL caused a similar increase in the fluorescence activity of the cells at 0.02 μL/mL comparing to the Verapamil® value. The antimicrobial assay was carried out according to the disc diffusion method. Five different bacterial strains (Staphylococcus epidermidis, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli AG 100, and Escherichia coli AG100A) were treated with the essential oils and the zones of inhibition were determined on TSA plates and TSA agar plates supplemented with Tween ...
In this study, polyphenols have been extracted from solid residues and leaves of olive tree (Olea... more In this study, polyphenols have been extracted from solid residues and leaves of olive tree (Olea europaea L) in order to assess this vegetable biomass by evaluation of their capacity as a natural antioxidants. The anti-oxidative activity was tested by addition of these extracts on commercial olive oil samples. The olive oil stability has been measured by accelerated oxidation under a simulated storage conditions (60°C/15 days). The change in the oxidation state was followed by measuring of the free acidity, peroxide value (PV) and the specific extinction at 270 nm. The assessment of enriched oils showed that polyphenols from olive by-products play a key role in reducing of oxidative deterioration of the oil. The results suggest the introduction of olive leaves and solid residues extracts in food preparation, both during storage or heating food, for better preservation.
Steroidal alkaloids are secondary metabolites mainly isolated from species of Solanaceae and Lili... more Steroidal alkaloids are secondary metabolites mainly isolated from species of Solanaceae and Liliaceae families that occurs mostly as glycoalkaloids. α-chaconine, α-solanine, solamargine and solasonine are among the steroidal glycoalkaloids commonly isolated from Solanum species. A number of investigations have demonstrated that steroidal glycoalkaloids exhibit a variety of biological and pharmacological activities such as antitumor, teratogenic, antifungal, antiviral, among others. However, these are toxic to many organisms and are generally considered to be defensive allelochemicals. To date, over 200 alkaloids have been isolated from many Solanum species, all of these possess the C27 cholestane skeleton and have been divided into five structural types; solanidine, spirosolanes, solacongestidine, solanocapsine, and jurbidine. In this regard, the steroidal C27 solasodine type alkaloids are considered as significant target of synthetic derivatives and have been investigated for more...
Glycolipids, carbohydrate fatty esters or sugar esters are amphiphilic molecules containing hydro... more Glycolipids, carbohydrate fatty esters or sugar esters are amphiphilic molecules containing hydrophilic groups bonded to hydrophobic parent structures. Recently, glycolipids have shown their antimicrobial and antitumor capacities. Their surface activity properties have applications in the food, pharmaceutical and cosmetic industries. Sugar esters' building blocks can be obtained from natural resources and/or be transformed by biochemical pathways for uses as surfactants. Biosurfactants are non-ionic, nontoxic, biodegradable, tasteless, and odourless. The biocatalysis of these molecules involves sustainable, green, and safer methods. The advantages of producing biosurfactants from enzymatic catalysis are the energy economy, high selectivity, production of natural products, reduction of the use of fossil-based solvents and chloride compounds. This review presents the most recent studies concerning the evaluation of the impact of the main parameters and their levels influencing the enzymatic synthesis of glycolipids. Various enzyme catalysed synthetic methods were described. The parameters studied were temperature, reaction time, solvent system, type of biocatalyst, substrates molar ratio proportion and the nature of substrates. This review discusses the influence of different biocatalysts in the conversions of glycolipids; The reactivity from mono to polysaccharides and their interaction with fatty acids of different carbon chain lengths in the presence of specific enzymes; The effect of the solvent polarity, the use of multiple solvents, ionic liquids, supercritical CO 2 , and solvent-free media in sugar ester conversions; And the optimization of temperature and reaction time in different enzymatic systems.
The use of agricultural by-products in the building engineering realm has led to an increase in i... more The use of agricultural by-products in the building engineering realm has led to an increase in insulation characteristics of biobased materials and a decrease in environmental impact. The understanding of cell wall structure is possible by the study of interactions of chemical compounds, themselves determined by common techniques like Van Soest (VS). In this study, a global method is investigated to characterise the cell wall of hemp shiv. The cell wall molecules were, at first, isolated by fractionation of biomass and then analysed by physical and chemical analysis (Thermal Gravimetric Analysis, Elementary Analysis, Dynamic Sorption Vapor and Infra-Red). This global method is an experimental way to characterise plant cell wall molecules of fractions by Thermal Gravimetric Analysis following by a mathematical method to have a detailed estimation of the cell wall composition and the interactions between plant macromolecules. The analyzed hemp shiv presents proportions of 2.5 ± 0.6% ...
Total phenolic compounds (TPC) and the chlorogenic acids content of potato by-product extracts of... more Total phenolic compounds (TPC) and the chlorogenic acids content of potato by-product extracts of two hydro alcoholic solvents (methanol, ethanol) and two extraction methods (maceration and heating-assisted extraction) were studied. The content of TPC in the extracts was determined spectrometrically according to the Folin–Ciocalteu procedure and calculated as chlorogenic acid equivalents. Soluble phenolic acids, especially the chlorogenic acids, were performed by HPLC. The antioxidant activity of potato by-product extracts was determined by using the total oxygen radical absorbance capacity (ORAC) method. The highest content of TPC was found in raw and lyophilized red waters when using ethanol as a solvent around 57 mg/g fresh weight. Heating-assisted extraction enhances this quantitative increasing. At the given operating conditions, unpeeled potato samples exhibit a higher TPC than peeled ones, showing that TPC are accumulated in skin tissue. The greatest amount of chlorogenic aci...
The capability of some polymers, such as chitosan, to form low cost gels under mild conditions is... more The capability of some polymers, such as chitosan, to form low cost gels under mild conditions is of great application interest. Ionotropic gelation of chitosan has been used predominantly for the preparation of gel beads for biomedical application. Only in the last few years has the use of this method been extended to the fabrication of chitosan-based flat structures. Herein, after an initial analysis of the major applications of chitosan flat membranes and films and their usual methods of synthesis, the process of ionotropic gelation of chitosan and some recently proposed novel procedures for the synthesis of flat structures are presented.
The curcumin degradation represents a significant limitation for its applications. The stability ... more The curcumin degradation represents a significant limitation for its applications. The stability of free curcumin (FC) and immobilized curcumin in complex particles (ComPs) based on different polysaccharides was studied under the action of several factors. Ultraviolet-visible (UV-VIS) and Fourier-transform infrared (FTIR) spectroscopy proved the FC photodegradation and its role as a metal chelator: 82% of FC and between 26% and 39.79% of curcumin within the ComPs degraded after exposure for 28 days to natural light. The degradation half-life (t1/2) decreases for FC when the pH increases, from 6.8 h at pH = 3 to 2.1 h at pH = 9. For curcumin extracted from ComPs, t1/2 was constant (between 10 and 13 h) and depended on the sample’s composition. The total phenol (TPC) and total flavonoids (TFC) content values increased by 16% and 13%, respectively, for FC exposed to ultraviolet light at λ = 365 nm (UVA), whereas no significant change was observed for immobilized curcumin. Antioxidant a...
Carotenoids have been implicated in protection of the eye from light-mediated photo-toxicity caus... more Carotenoids have been implicated in protection of the eye from light-mediated photo-toxicity caused by free radicals. Under conditions of normal oxidative stress the carotenoids serve as protective antioxidants; however, when the oxidative stress exceeds the antioxidant capacity, carotenoids can be oxidized into numerous cleavage products. The determination and identification of oxidized carotenoids in biological samples remains a major challenge due to the small sample size and low stability of these compounds. We investigated the reaction of various zeaxanthin cleavage products with O-ethyl hydroxylamine to evaluate their levels in a biological sample. For this, a sensitive and specific electrospray tandem mass spectrometry (ESI-MS/MS) was developed, avoiding the classical lower sensitive and specific HPLC-UV and fluorescence absorption methods. Protonated molecules [M + H] + of carotenoids upon collision-induced dissociation produced a number of structurally characteristic product ions. A series of complicated clusters of product ions differing in 14 (CH 2)and 26 (C 2 H 2)Da was characteristic of the polyene chain of intact carotenoids. All carotenoid ethyl oximes of zeaxanthin cleavage products were characterized by the losses of 60 and 61 Da in their MS/MS spectra. Through the application of the LC/MS/MS method, we identified two oxime derivatives of 3-hydroxy-b-ionone and 3-hydroxy-14-apocarotenal with protonated molecules at m/z 252 and m/z 370 respectively, in a human eye sample.
The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is curre... more The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is currently the most devastating foliar disease on wheat crops worldwide. Here, we explored, for the first time, the ability of rhamnolipids (RLs) to control this pathogen, using a total of 19 RLs, including a natural RL mixture produced by Pseudomonas aeruginosa and 18 bioinspired RLs synthesized using green chemistry, as well as two related compounds (lauric acid and dodecanol). These compounds were assessed for in vitro antifungal effect, in planta defence elicitation (peroxidase and catalase enzyme activities), and protection efficacy on the wheat-Z. tritici pathosystem. Interestingly, a structure-activity relationship analysis revealed that synthetic RLs with a 12 carbon fatty acid tail were the most effective for all examined biological activities. This highlights the importance of the C12 chain in the bioactivity of RLs, likely by acting on the plasma membranes of both wheat and Z. triti...
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