15 research outputs found
Recherche de molécules antimicrobiennes d'origine lichénique : Etude phytochimique de trois lichens & approche synthétique de deux composés actifs
Phytochemical study of three lichens collected in Limousin, Usnea florida, Flavoparmelia caperata and Cladonia incrassata, led to the isolation and the structural identification of 16 secondary metabolites. First, these lichens were chosen after a preliminary screening performed on 17 species. Antimicrobial activity of acetone extracts was evaluated and bioassay-guided fractionation was performed. The two isomers of usnic acid, 3 dibenzofurans, 4 depsides, 3 depsidones, one aliphatic acid and one sterol were isolated. A trichlorinated xanthone, named cladoxanthone A, was extracted and identified for the first time in a natural source. A bioautographic protocol was used to evaluate antibacterial activities of these compounds on Staphylococcus aureus. MICs of the products obtained in sufficient amounts were determined by a broth microdilution method in parallel with PhenonipÂź, a preservative commonly used in cosmetic industry. Didymic and condidymic acids were found to be good candidates for use as preservatives. Secondly, owing to their potential industrial application, we explored synthetic routes for usnic acid and cladoxanthone A. Thus, the preparation of the key intermediate for access to usnic acid was optimized and the first coupling tests in the presence of a porphyrin were encouraging. Similarly, the proposed synthetic routes for cladoxanthone A are promising.LâĂ©tude physicochimique de trois lichens rĂ©coltĂ©s en Limousin, Usnea florida, Flavoparmelia caperata et Cladonia incrassata, a permis dâisoler et de caractĂ©riser 16 composĂ©s issus du mĂ©tabolisme secondaire. Dans un premier temps, ces lichens ont Ă©tĂ© sĂ©lectionnĂ©s lors dâun criblage analytique prĂ©liminaire rĂ©alisĂ© sur 17 espĂšces. LâactivitĂ© antimicrobienne des extraits acĂ©toniques a Ă©tĂ© Ă©valuĂ©e, puis leur fractionnement bioguidĂ© a Ă©tĂ© mis en Ćuvre. Les deux isomĂšres de lâacide usnique, 3 dibenzofuranes, 4 depsides, 3 depsidones, un acide aliphatique, un phtalide et un stĂ©rol ont Ă©tĂ© isolĂ©s. Une xanthone trichlorĂ©e, la cladoxanthone A, a Ă©tĂ© extraite et identifiĂ©e pour la premiĂšre fois Ă partir dâune source naturelle. Lâeffet de tous les composĂ©s a Ă©tĂ© Ă©valuĂ© sur Staphyloccocus aureus par bioautographie. Pour les produits isolĂ©s en quantitĂ© suffisante, des tests de dilution en milieu liquide ont permis de dĂ©terminer leurs CMI, en comparaison avec le PhĂ©nonipÂź, conservateur couramment utilisĂ© dans lâindustrie cosmĂ©tique. Les acides didymique et condidymique en particulier sâavĂšrent ĂȘtre de bons candidats pour une utilisation en tant que conservateurs. Dans un second temps, compte tenu de leur potentielle application industrielle, nous avons explorĂ© des voies de synthĂšse de lâacide usnique et de la cladoxanthone A. Ainsi, la prĂ©paration de lâintermĂ©diaire clĂ© pour lâaccĂšs Ă lâacide usnique a Ă©tĂ© optimisĂ©e et les premiers essais de couplage en prĂ©sence dâune porphyrine sont encourageants. De mĂȘme, les voies de synthĂšse proposĂ©es et mises en Ćuvre pour la cladoxanthone A sont prometteuses
Mitochondrial physiology
As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
Mitochondrial physiology
As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
The GEOTRACES Intermediate Data Product 2014
The GEOTRACES Intermediate Data Product 2014 (IDP2014) is the first publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2013. It consists of two parts: (1) a compilation of digital data for more than 200 trace elements and isotopes (TEIs) as well as classical hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing a strongly inter-linked on-line atlas including more than 300 section plots and 90 animated 3D scenes. The IDP2014 covers the Atlantic, Arctic, and Indian oceans, exhibiting highest data density in the Atlantic. The TEI data in the IDP2014 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at cross-over stations. The digital data are provided in several formats, including ASCII spreadsheet, Excel spreadsheet, netCDF, and Ocean Data View collection. In addition to the actual data values the IDP2014 also contains data quality flags and 1-? data error values where available. Quality flags and error values are useful for data filtering. Metadata about data originators, analytical methods and original publications related to the data are linked to the data in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2014 data providing section plots and a new kind of animated 3D scenes. The basin-wide 3D scenes allow for viewing of data from many cruises at the same time, thereby providing quick overviews of large-scale tracer distributions. In addition, the 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of observed tracer plumes, as well as for making inferences about controlling processes
Research of antimicrobial molecules from lichens : Phytochemical study of three lichens and synthetic approach of two active compounds
LâĂ©tude physicochimique de trois lichens rĂ©coltĂ©s en Limousin, Usnea florida, Flavoparmelia caperata et Cladonia incrassata, a permis dâisoler et de caractĂ©riser 16 composĂ©s issus du mĂ©tabolisme secondaire. Dans un premier temps, ces lichens ont Ă©tĂ© sĂ©lectionnĂ©s lors dâun criblage analytique prĂ©liminaire rĂ©alisĂ© sur 17 espĂšces. LâactivitĂ© antimicrobienne des extraits acĂ©toniques a Ă©tĂ© Ă©valuĂ©e, puis leur fractionnement bioguidĂ© a Ă©tĂ© mis en Ćuvre. Les deux isomĂšres de lâacide usnique, 3 dibenzofuranes, 4 depsides, 3 depsidones, un acide aliphatique, un phtalide et un stĂ©rol ont Ă©tĂ© isolĂ©s. Une xanthone trichlorĂ©e, la cladoxanthone A, a Ă©tĂ© extraite et identifiĂ©e pour la premiĂšre fois Ă partir dâune source naturelle. Lâeffet de tous les composĂ©s a Ă©tĂ© Ă©valuĂ© sur Staphyloccocus aureus par bioautographie. Pour les produits isolĂ©s en quantitĂ© suffisante, des tests de dilution en milieu liquide ont permis de dĂ©terminer leurs CMI, en comparaison avec le PhĂ©nonipÂź, conservateur couramment utilisĂ© dans lâindustrie cosmĂ©tique. Les acides didymique et condidymique en particulier sâavĂšrent ĂȘtre de bons candidats pour une utilisation en tant que conservateurs. Dans un second temps, compte tenu de leur potentielle application industrielle, nous avons explorĂ© des voies de synthĂšse de lâacide usnique et de la cladoxanthone A. Ainsi, la prĂ©paration de lâintermĂ©diaire clĂ© pour lâaccĂšs Ă lâacide usnique a Ă©tĂ© optimisĂ©e et les premiers essais de couplage en prĂ©sence dâune porphyrine sont encourageants. De mĂȘme, les voies de synthĂšse proposĂ©es et mises en Ćuvre pour la cladoxanthone A sont prometteuses.Phytochemical study of three lichens collected in Limousin, Usnea florida, Flavoparmelia caperata and Cladonia incrassata, led to the isolation and the structural identification of 16 secondary metabolites. First, these lichens were chosen after a preliminary screening performed on 17 species. Antimicrobial activity of acetone extracts was evaluated and bioassay-guided fractionation was performed. The two isomers of usnic acid, 3 dibenzofurans, 4 depsides, 3 depsidones, one aliphatic acid and one sterol were isolated. A trichlorinated xanthone, named cladoxanthone A, was extracted and identified for the first time in a natural source. A bioautographic protocol was used to evaluate antibacterial activities of these compounds on Staphylococcus aureus. MICs of the products obtained in sufficient amounts were determined by a broth microdilution method in parallel with PhenonipÂź, a preservative commonly used in cosmetic industry. Didymic and condidymic acids were found to be good candidates for use as preservatives. Secondly, owing to their potential industrial application, we explored synthetic routes for usnic acid and cladoxanthone A. Thus, the preparation of the key intermediate for access to usnic acid was optimized and the first coupling tests in the presence of a porphyrin were encouraging. Similarly, the proposed synthetic routes for cladoxanthone A are promising
Research of antimicrobial molecules from lichens : Phytochemical study of three lichens and synthetic approach of two active compounds
LâĂ©tude physicochimique de trois lichens rĂ©coltĂ©s en Limousin, Usnea florida, Flavoparmelia caperata et Cladonia incrassata, a permis dâisoler et de caractĂ©riser 16 composĂ©s issus du mĂ©tabolisme secondaire. Dans un premier temps, ces lichens ont Ă©tĂ© sĂ©lectionnĂ©s lors dâun criblage analytique prĂ©liminaire rĂ©alisĂ© sur 17 espĂšces. LâactivitĂ© antimicrobienne des extraits acĂ©toniques a Ă©tĂ© Ă©valuĂ©e, puis leur fractionnement bioguidĂ© a Ă©tĂ© mis en Ćuvre. Les deux isomĂšres de lâacide usnique, 3 dibenzofuranes, 4 depsides, 3 depsidones, un acide aliphatique, un phtalide et un stĂ©rol ont Ă©tĂ© isolĂ©s. Une xanthone trichlorĂ©e, la cladoxanthone A, a Ă©tĂ© extraite et identifiĂ©e pour la premiĂšre fois Ă partir dâune source naturelle. Lâeffet de tous les composĂ©s a Ă©tĂ© Ă©valuĂ© sur Staphyloccocus aureus par bioautographie. Pour les produits isolĂ©s en quantitĂ© suffisante, des tests de dilution en milieu liquide ont permis de dĂ©terminer leurs CMI, en comparaison avec le PhĂ©nonipÂź, conservateur couramment utilisĂ© dans lâindustrie cosmĂ©tique. Les acides didymique et condidymique en particulier sâavĂšrent ĂȘtre de bons candidats pour une utilisation en tant que conservateurs. Dans un second temps, compte tenu de leur potentielle application industrielle, nous avons explorĂ© des voies de synthĂšse de lâacide usnique et de la cladoxanthone A. Ainsi, la prĂ©paration de lâintermĂ©diaire clĂ© pour lâaccĂšs Ă lâacide usnique a Ă©tĂ© optimisĂ©e et les premiers essais de couplage en prĂ©sence dâune porphyrine sont encourageants. De mĂȘme, les voies de synthĂšse proposĂ©es et mises en Ćuvre pour la cladoxanthone A sont prometteuses.Phytochemical study of three lichens collected in Limousin, Usnea florida, Flavoparmelia caperata and Cladonia incrassata, led to the isolation and the structural identification of 16 secondary metabolites. First, these lichens were chosen after a preliminary screening performed on 17 species. Antimicrobial activity of acetone extracts was evaluated and bioassay-guided fractionation was performed. The two isomers of usnic acid, 3 dibenzofurans, 4 depsides, 3 depsidones, one aliphatic acid and one sterol were isolated. A trichlorinated xanthone, named cladoxanthone A, was extracted and identified for the first time in a natural source. A bioautographic protocol was used to evaluate antibacterial activities of these compounds on Staphylococcus aureus. MICs of the products obtained in sufficient amounts were determined by a broth microdilution method in parallel with PhenonipÂź, a preservative commonly used in cosmetic industry. Didymic and condidymic acids were found to be good candidates for use as preservatives. Secondly, owing to their potential industrial application, we explored synthetic routes for usnic acid and cladoxanthone A. Thus, the preparation of the key intermediate for access to usnic acid was optimized and the first coupling tests in the presence of a porphyrin were encouraging. Similarly, the proposed synthetic routes for cladoxanthone A are promising
Dibenzofurans and derivatives from lichens and ascomycetes
International audienceCovering: up to 2016.When looking for dibenzofuran in the biochemical databases, most papers and reviews deal with pollutants and polychlorinated dibenzofurans like dioxins. But dibenzofurans are also biosynthetized by a wide diversity of organisms in nature. Even if dibenzofurans from natural sources represent a small class of secondary metabolites, compared to flavonoids, xanthones or terpenoids, they are often endowed with interesting biological properties which have been recently described. This review provides an update on papers describing dibenzofurans from lichens, ascomycetes and cultured mycobionts. Other sources, such as basidiomycetes, myxomycetes or plants produce sporadically interesting dibenzofurans in terms of structures and activitie
Uncommon Chlorinated Xanthone and Other Antibacterial Compounds from the Lichen Cladonia incrassata
International audienceBioassay-guided fractionation of an extract of the lichen Cladonia incrassata against Staphylococcus aureus led to a novel compound, 1,5-dihydroxy-2,4,6-trichloro-7-methylxanthone (1), along with six known compounds: (â)-usnic acid (2), didymic acid (3), condidymic acid (4), squamatic acid (5), thamnolic acid (6), and prasinic acid (7). Didymic, condidymic, and prasinic acids were isolated for the first time from C. incrassata. Didymic, condidymic, and (â)-usnic acids were active against S. aureus (a minimum inhibitory concentration of 7.5â”g/mL)
A differential proteomic approach to assess the effects of chemotherapeutics and production management strategy on giant tiger shrimp Penaeus monodon
Understanding the Thermal Runaway of Ni-Rich Lithium-Ion Batteries
International audienceThe main safety issue pertaining to operating lithium-ion batteries (LIBs) relates to their sensitivity to thermal runaway. This complex multiphysics phenomenon was observed in two commercial 18650 Ni-rich LIBs, namely a Panasonic NCR GA and a LG HG2, which were based on Li(Ni 0.8 Co 0.15 Al 0.05)O 2 (NCA) and Li(Ni 0.8 Mn 0.1 Co 0.1)O 2 (NMC811), respectively, for positive electrodes, in combination with graphite-SiO x composite negative electrodes. At pristine state, the batteries were charged to different levels of state of charge (SOC) (100% and 50%) and were investigated through thermal abuse tests in quasi-adiabatic conditions of accelerating rate calorimetry (ARC). The results confirmed the proposed complete thermal runaway of exothermic chain reactions. The different factors impacting the thermal runaway kinetics were also studied by considering the intertwined impacts of SOC and the related properties of these highly reactive Ni-rich technologies. All tested cells started their accelerated thermal runaway stage at the same self-heating temperature rate of~48 âą C/min. Regardless of technology, cells at reduced SOC are less reactive. Regardless of SOC levels, the Panasonic NCR GA battery technology had a wider safe region than that of the LG HG2 battery. This technology also delayed the hard internal short circuit and shifted the final venting to a higher temperature. However, above this critical temperature, it exhibited the most severe irreversible self-heating stage, with the highest self-heating temperature rate over the longest duration