Evaluación de combinaciones de aceites esenciales y aceites esenciales con hidrosoles sobre actividades antimicrobianas y antioxidantes]

International audienceContext: Essential oils (EO) are commonly extracted from plants by steam distillation in which an aqueous phase called hydrosol (HD) is obtained. Unlike EO, hydrosol studies have been limited despite the interest of the food, cosmetic and phytotherapeutic industries to find natural preservative alternatives to synthetic ones. Aims: To evaluate the in vitro antimicrobial and antioxidant efficacies of combinations of essential oils (EOs) and essential oils and hydrosols (HDs) of Lippia alba, Rosmarinus officinalis, and Thymus vulgaris. Methods: The EOs and HDs were characterized by gas chromatography with flame ionization detector and gas chromatography coupled with mass spectrometry. Then, they were screened against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus niger using the microdilution method for the four first strains and the agar diffusion method for Aspergillus niger. Antioxidant capacity was evaluated using ABTS method. Results: Interactions between essential oils, and essential oils and hydrosols were found to be as microbicide, and for the first time, antioxidant using the fractional inhibitory concentration. When compared with individual EOs, EO-EO combinations diminished the microbicide minimum concentration. Conclusions: The Thymus vulgaris EO-HD combination, in comparison with individual extracts, diminishes by four times the MBC against Escherichia coli and decrease by half their antioxidant capacity.Contexto: Los aceites esenciales (AEs) se extraen comúnmente de las plantas por destilación con arrastre de vapor en la que se obtiene una faseacuosa llamada hidrosol (HDs). A diferencia de los AE, los estudios de los HD han sido limitados a pesar del interés de las industrias alimentaria,cosmética y fitoterapéutica de encontrar alternativas naturales de conservación.Objetivos: Evaluar la eficacia antimicrobiana y antioxidante in vitro de las combinaciones de AEs, AEs e HDs de Lippia alba, Rosmarinus officinalis y Thymus vulgaris.Métodos: Los AEs e HDs fueron caracterizados por cromatografía de gases con detector de ionización en llama y cromatografía de gases acoplada a espectrometría de masas. Luego se realizaron pruebas de detección contra Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans y Aspergillus niger utilizando el método de microdilución para las cuatro primeras cepas y el método de difusión en agar para Aspergillus niger. La actividad antioxidante se evaluó utilizando el método ABTS.Resultados: Se encontró que las interacciones entre los aceites esenciales, aceites esenciales e hidrosoles eran microbicidas y, por primera vez,antioxidantes usando la concentración inhibidora fraccionada. Cuando se compararon con AEs individuales, las combinaciones AE-AEdisminuyeron la concentración microbicida mínima.Conclusiones La combinación de tomillo AE-HD; en comparación con los extractos individuales, disminuye en cuatro veces el MBC contraEscherichia coli y disminuye a la mitad su actividad antioxidante

Phytochemical, antioxidant and antimicrobial parameters of essential oils and hydrosols of colombian Thyme and Rosemary obtained using two different steam distillation methods

Two procedures of steam distillation of Rosmarinus officinalis and Thymus vulgaris were compared by phytochemical, antioxidant and antimicrobial analysis of their respective essential oils and hydrosols using respectively GCFID and GCMS analysis, free radical scavenging activity on ABTS and dilution and diffusion method against 3 bacteria and 2 fungi. Differences in bioactivity results are discussed taking into account changes in molecular content of essential oils and hydrosols obtained by the two different distillation methods. Although no significant difference was observed between the two procedures with Rosmarinus officinalis, that was not the case with Thymus vulgaris. Significant differences were noted, not only in their respective chemical composition especially with the thymol and p-cymene percentage with respectively a change from 39% with conventional steam distillation to 27% with adapted steam distillation for thymol and from 28% with the first distillation to 37% with the second one for p-cymene. These phytochemical composition changes have an impact on their biological activities results and consequently on the therapeutic activities expected which shows the importance of distillation method selection

Les connaissances scientifiques, une ressource de plus en plus rare pour la décision publique ?

JEL classification : D80; E61; Q10; Q57Cet article montre la nécessité de réintégrer dans l’analyse des politiques économiques les enjeux de l’évolution des modalités d’accès aux connaissances, en particulier aux connaissances scientifiques. Après être revenus sur la notion de régime de connaissances, il étudie la façon dont des connaissances scientifiques sont mobilisées et évaluées pour concevoir des mesures agri-environnementales, domaine d’intervention publique important où prolifèrent les prescriptions réglementaires. L’analyse repose sur des entretiens conduits auprès des services de l’État en charge de la rédaction du contenu technique de ces mesures d’intervention réglementaires, et auprès de divers types d’acteurs impliqués dans le débat public sur le contenu technique de ces mesures. Elle montre que la capacité d’accéder aux connaissances, d’en évaluer la fiabilité, qui est souvent considérée comme non problématique dans l’analyse des politiques publiques est aussi un des points cruciaux des reconfigurations actuelles. Elle invite à ne pas oublier que les politiques publiques mobilisent des outils qui sont à la fois outils de gouvernement et outils de preuve. S’il est nécessaire d’analyser dans les champs des sciences politiques les principes de gouvernement dont sont porteurs ces outils, pour autant il importe de ne pas renoncer à la réflexion sur la fiabilité des preuves

Fractionnement de graines oléo-protéagineuses en extrusion bi-vis : applications en formulation cosmétique

International audienc

Correlation of the Electrochemical Kinetics of High-Salinity-Tolerant Bioanodes with the Structure and Microbial Composition of the Biofilm

International audienceIncreasing the conductivity of the electrolytes used in microbial electrochemical systems is an essential prerequisite to large‐scale application of these technologies. Microbial anodes formed on carbon felt from a salt marsh inoculum under polarisation at 0.1 V (versus a saturated calomel electrode), generated up to 85 A m−2 in media that contained 30–45 g L−1 of NaCl. Analyses of microbial populations showed a stringent selection of the two microbial genera Marinobacter and Desulfuromonas. Currents decreased if NaCl concentration was increased to 60 g L−1. This highest salinity was shown to consistently impact the bioanode performance in three ways: voltammetry indicated degraded electron‐transfer kinetics, confocal laser scanning microscopy showed a modified biofilm structure and DNA pyrosequencing detected a decrease in the level of Desulfuromonas spp. relative to Marinobacter spp. A consistent correlation was, thus, found between electrochemical kinetics, biofilm structure and the composition of the microbial community

Evaluation of combinations of essential oils and essential oils with hydrosols on antimicrobial and antioxidant activities

Context: Essential oils (EO) are commonly extracted from plants by steam distillation in which an aqueous phase called hydrosol (HD) is obtained. Unlike EO, hydrosol studies have been limited despite the interest of the food, cosmetic and phytotherapeutic industries to find natural preservative alternatives to synthetic ones. Aims: To evaluate the in vitro antimicrobial and antioxidant efficacies of combinations of essential oils (EOs) and essential oils and hydrosols (HDs) of Lippia alba, Rosmarinus officinalis, and Thymus vulgaris. Methods: The EOs and HDs were characterized by gas chromatography with flame ionization detector and gas chromatography coupled with mass spectrometry. Then, they were screened against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus niger using the microdilution method for the four first strains and the agar diffusion method for Aspergillus niger. Antioxidant capacity was evaluated using ABTS method. Results: Interactions between essential oils, and essential oils and hydrosols were found to be as microbicide, and for the first time, antioxidant using the fractional inhibitory concentration. When compared with individual EOs, EO-EO combinations diminished the microbicide minimum concentration. Conclusions: The Thymus vulgaris EO-HD combination, in comparison with individual extracts, diminishes by four times the MBC against Escherichia coli and decrease by half their antioxidant capacity

Halotolerant bioanodes: The applied potential modulates the electrochemical characteristics, the biofilm structure and the ratio of the two dominant genera

The development of economically-efficient microbial electrochemical technologies remains hindered by the low ionic conductivity of the culture media used as the electrolyte. To overcome this drawback, halotolerant bioanodes were designed with salt marsh sediment used as the inoculum in electrolytes containing NaCl at 30 or 45 g/L (ionic conductivity 7.0 or 10.4 S·m− 1). The bioanodes were formed at four different potentials − 0.4, − 0.2, 0.0 and 0.2 V/SCE to identify the effect on the electrochemical kinetic parameters, the biofilm structures and the composition of the microbial communities. The bioanodes formed at − 0.4 V/SCE were largely dominated by Marinobacter spp. Voltammetry showed that they provided higher currents than the other bioanodes in the range of low potentials, but the maximum currents were limited by the poor surface colonization. The bioanodes formed at − 0.2, 0.0 and 0.2 V/SCE showed similar ratios of Marinobacter and Desulfuromonas spp. and higher values of the maximum current density. The combined analysis of kinetic parameters, biofilm structure and biofilm composition showed that Marinobacter spp., which ensured a higher electron transfer rate, were promising species for the design of halotolerant bioanodes. The challenge is now to overcome its limited surface colonization in the absence of Desulfuromonas spp

Complementary use of mass spectrometry and cryo-electron microscopy to assess the maturity of live attenuated dengue vaccine viruses

International audienc