17 research outputs found
Isolation and semisynthesis of guttiférone A analogs
La guttifĂ©rone A , appartenant Ă la famille des PPAPs ou Acyle Phloroglucinol Polycycliques PolyprĂ©nylĂ©es, est une molĂ©cule extraite Ă partir dâun arbre tropicale, le Symphonia globulifera. Cette matiĂšre premiĂšre est abondante et peut ĂȘtre facilement obtenue. De plus, elle prĂ©sente de nombreuses activitĂ©s biologiques, lui confĂ©rant un potentiel pharmacologique trĂšs intĂ©ressant. Trois approches ont Ă©tĂ© effectuĂ©es durant ces travaux. La premiĂšre fĂ»t lâutilisation de microorganismes pour effectuer des biotransformations. Lâutilisation de levures a permis de synthĂ©tiser la 3,16-oxy-guttifĂ©rone A, forme xanthone de la guttifĂ©rone. Le second axe a Ă©tĂ© dâutiliser des outils chimiques pour obtenir des dĂ©rivĂ©s de la guttifĂ©rone A. Dans un premier temps, une vingtaine dâanalogues Ă©ther et ester du catĂ©chol a Ă©tĂ© synthĂ©tisĂ©e, certains de ces composĂ©s ont montrĂ© un meilleur indice de sĂ©lectivitĂ© sur les parasites. Une synthĂšse sĂ©lective de xanthone par une rĂ©action de couplage phĂ©nolique oxydatif a Ă©galement Ă©tĂ© Ă©tudiĂ©e. Nous avons pu obtenir par cette approche la 3,16-oxy-guttifĂ©rone A, la 1,16-oxy-guttifĂ©rone A et la 1,12-oxy-guttifĂ©rone A. Ces rĂ©actions ont aussi donnĂ© accĂšs Ă des dĂ©rivĂ©s xanthone hydroxylĂ©e jamais dĂ©crits dans la littĂ©rature. Enfin, un travail prĂ©liminaire de phytochimie sur les graines et feuilles du Symphonia globulifera a Ă©tĂ© rĂ©alisĂ©, permettant dâisoler des analogues de la guttifĂ©rone A, la guttifĂ©rone C et D, ainsi que dâautres molĂ©cules comme des bisflavonoides et des xanthones.Guttiferone A, belonging to the PPAPs family (Polycyclic Polyprenylated Acylphloroglucinols), is extracted from a tropical tree called Symphonia globulifera. This raw material is abundant and can be easily obtained. In addition, it has many biological activities, giving it a very interesting pharmacological potential. Three approaches were used in this work. The first was the use of microorganisms to perform biotransformations. The use of yeast allow the synthesis of 3,16-oxy-guttifĂ©rone A, a xanthone derivative of guttiferone A. The second theme was the use of chemical tools for guttiferone A derivation. First, twenty ether and ester catechol analogs were synthesized, some of these compounds showed a better selectivity index of parasites. Selective synthesis of xanthone by phenolic oxidative coupling reaction was also studied. We obtained by this approach the 3.16-oxy-guttiferone A, 1,16-oxy-guttiferone A and 1,12-oxy-guttiferone A. These reactions have also provided some hydroxylated xanthone never described before in the literature. Finally, preliminary phytochemical work on seeds and leaves of Symphonia globulifera lead to the isolation of guttifĂ©rone A analogues such as guttifĂ©rone C and D, as well as other molecules such as bisflavonoides and xanthones
Extraction et hémisynthÚse d'analogues de la guttiférone A
La guttifĂ©rone A , appartenant Ă la famille des PPAPs ou Acyle Phloroglucinol Polycycliques PolyprĂ©nylĂ©es, est une molĂ©cule extraite Ă partir d un arbre tropicale, le Symphonia globulifera. Cette matiĂšre premiĂšre est abondante et peut ĂȘtre facilement obtenue. De plus, elle prĂ©sente de nombreuses activitĂ©s biologiques, lui confĂ©rant un potentiel pharmacologique trĂšs intĂ©ressant. Trois approches ont Ă©tĂ© effectuĂ©es durant ces travaux. La premiĂšre fĂ»t l utilisation de microorganismes pour effectuer des biotransformations. L utilisation de levures a permis de synthĂ©tiser la 3,16-oxy-guttifĂ©rone A, forme xanthone de la guttifĂ©rone. Le second axe a Ă©tĂ© d utiliser des outils chimiques pour obtenir des dĂ©rivĂ©s de la guttifĂ©rone A. Dans un premier temps, une vingtaine d analogues Ă©ther et ester du catĂ©chol a Ă©tĂ© synthĂ©tisĂ©e, certains de ces composĂ©s ont montrĂ© un meilleur indice de sĂ©lectivitĂ© sur les parasites. Une synthĂšse sĂ©lective de xanthone par une rĂ©action de couplage phĂ©nolique oxydatif a Ă©galement Ă©tĂ© Ă©tudiĂ©e. Nous avons pu obtenir par cette approche la 3,16-oxy-guttifĂ©rone A, la 1,16-oxy-guttifĂ©rone A et la 1,12-oxy-guttifĂ©rone A. Ces rĂ©actions ont aussi donnĂ© accĂšs Ă des dĂ©rivĂ©s xanthone hydroxylĂ©e jamais dĂ©crits dans la littĂ©rature. Enfin, un travail prĂ©liminaire de phytochimie sur les graines et feuilles du Symphonia globulifera a Ă©tĂ© rĂ©alisĂ©, permettant d isoler des analogues de la guttifĂ©rone A, la guttifĂ©rone C et D, ainsi que d autres molĂ©cules comme des bisflavonoides et des xanthones.Guttiferone A, belonging to the PPAPs family (Polycyclic Polyprenylated Acylphloroglucinols), is extracted from a tropical tree called Symphonia globulifera. This raw material is abundant and can be easily obtained. In addition, it has many biological activities, giving it a very interesting pharmacological potential. Three approaches were used in this work. The first was the use of microorganisms to perform biotransformations. The use of yeast allow the synthesis of 3,16-oxy-guttifĂ©rone A, a xanthone derivative of guttiferone A. The second theme was the use of chemical tools for guttiferone A derivation. First, twenty ether and ester catechol analogs were synthesized, some of these compounds showed a better selectivity index of parasites. Selective synthesis of xanthone by phenolic oxidative coupling reaction was also studied. We obtained by this approach the 3.16-oxy-guttiferone A, 1,16-oxy-guttiferone A and 1,12-oxy-guttiferone A. These reactions have also provided some hydroxylated xanthone never described before in the literature. Finally, preliminary phytochemical work on seeds and leaves of Symphonia globulifera lead to the isolation of guttifĂ©rone A analogues such as guttifĂ©rone C and D, as well as other molecules such as bisflavonoides and xanthones.PARIS5-Bibliotheque electronique (751069902) / SudocPARIS-BIUM-Bib. Ă©lectronique (751069903) / SudocSudocFranceF
Effect of thread milling penetration strategies on the dimensional accuracy
Day by day the application of thread milling process is enhancing in industry because of its inherent advantages over other thread cutting techniques. The current study dwells on the interference issue, which is generated during thread milling. It was observed that there are two sources of interference on the thread produced i.e interference induced during mill penetration and during full machining. This interference leads to an overcut on the thread, thus it produces dimensionally inaccurate thread. The interference produced by penetration is much more as compared to interference generated during full machining of thread. Thus, there is a pressing need to analyze interference during penetration. So this study evaluates different applied penetration strategies and the level of interference produced. Further, the study suggests modified penetration strategies in order to reduce the interference produced and hence create more accurate thread. This investigation is supported by analytical modeling and experimental exploration.Postdoc financé par Conseil Régional de Bourgogone Collaboration avec l'entreprise WALTER PROTOTY
Update of the French aerial survey index of abundance and first attempt at integrating bluefin tuna school size estimates from video cameras
The French aerial survey provide an important fisheries independent index for the stock assessment of Eastern Atlantic Bluefin Tuna (EABFT, Thunnus thynnus). However, this survey presents several shortcomings. The main issue is linked to the absence of quantitative estimate of the size of the different school types encountered during the survey. This prevents from accounting to changes in school size composition, which could affect the trends of the index. Since 2016 video cameras were set-up under the aircraft to record the flights and obtain school size estimates. In addition to the 2017 update of the index, the present manuscript describes the procedure to estimate school size from the videos and presents preliminary results for an index integrating this new information. Robustness to school type assignment and school size variability are investigated through bootstrap approaches. The results show distinct surfaces for the different school types and that including school sizes into the index leads to a comparable long-term trend, but with higher values for 2009-2012 than without including the school surfaces.La prospecciĂłn aĂ©rea francesa proporciona un importante Ăndice independiente de la pesquerĂa para la evaluaciĂłn del stock de atĂșn rojo del AtlĂĄntico oriental (EABFT, Thunnus thynnus). Sin embargo, esta prospecciĂłn presenta diversas deficiencias. El principal problema estĂĄ relacionado con la falta una estimaciĂłn cuantitativa del tamaño de los diferentes tipos de bancos hallados durante la prospecciĂłn. Esto impide tener en cuenta los cambios en la composiciĂłn por tallas del banco, lo que podrĂa afectar a las tendencias del Ăndice. Desde 2016, se colocaron cĂĄmaras de vĂdeo bajo la aeronave para grabar los vuelos y obtener estimaciones del tamaño de los bancos. AdemĂĄs de la actualizaciĂłn del Ăndice de 2017, el presente documento describe el procedimiento para estimar el tamaño de los bancos a partir de los vĂdeos y presenta resultados preliminares para un Ăndice que integre esta nueva informaciĂłn. Se investiga la robustez ante la asignaciĂłn al tipo de banco y la variabilidad en el tamaño del banco mediante enfoques de bootstrap. Los resultados demuestran superficies diferentes para los distintos tipos de bancos y que incluir el tamaño del banco en el Ăndice conduce a una tendencia a largo plazo comparable, pero con valores mĂĄs elevados para 2009- 2012 que sin incluir las superficies de los bancos.La prospecciĂłn aĂ©rea francesa en el golfo de LeĂłn proporciona un importante Ăndice independiente de la pesquerĂa para la evaluaciĂłn del stock de atĂșn rojo del AtlĂĄntico este (EABFT, Thunnus thynnus). El presente documento recuerda la metodologĂa empleada para la prospecciĂłn y proporciona la actualizaciĂłn del Ăndice para el año 2021, que muestra un ligero descenso respecto a 2020, que fue el año con el valor mĂĄs elevado hasta la fecha, pero ocupa el tercer puesto en cuanto al valor mĂĄs alto. Lo que confirma la tendencia al alza de los Ășltimos años
Modélisation géometrique du filetage à la fraise
Les opĂ©rations de fraisage sont relativement complexes Ă mettre au point car il y a de nombreux paramĂštres de coupe et caractĂ©ristiques gĂ©omĂ©triques de lâoutil. De plus, les efforts de coupe varient en usinage, du fait de la discontinuitĂ© de la coupe. La modĂ©lisation des opĂ©rations de fraisage et la dĂ©termination des efforts de coupe devraient permettre dâĂ©valuer, rapidement et avec peu dâessais, lâeffet de paramĂštres gĂ©omĂ©triques de lâoutil et des conditions de coupe, et dĂ©finir ainsi un domaine dâutilisation acceptable. Toutefois pour rĂ©aliser cet objectif, il est nĂ©cessaire de disposer de modĂšles robustes et capables de reproduire lâeffet de diffĂ©rents paramĂštres, en particulier ceux liĂ©s Ă la gĂ©omĂ©trie de lâoutil. Le filetage Ă la fraise est une technique qui permet de gĂ©nĂ©rer aussi bien des filets intĂ©rieurs quâextĂ©rieurs par interpolation hĂ©licoĂŻdale avec un outil ayant le profil du filet. Cette technique possĂšde plusieurs avantages, notamment par rapport au taraudage, et sâavĂšre adaptĂ©e au contexte de production de piĂšces Ă forte valeur ajoutĂ©e. Dâun point de vue gĂ©omĂ©trique, le filetage Ă la fraise est une configuration dâusinage 3D complexe, et ceci par la trajectoire, la gĂ©omĂ©trie de coupe de lâoutil et la section coupĂ©e. LâĂ©tude proposĂ©e traite de la modĂ©lisation gĂ©omĂ©trique du filetage Ă la fraise qui est une Ă©tape prĂ©liminaire indispensable notamment Ă la modĂ©lisation des efforts de coupe. Lâapproche dĂ©veloppĂ©e expose une formulation analytique complĂšte de la gĂ©omĂ©trie de la fraise (arĂȘte de coupe, face de coupe, face en dĂ©pouille) et examine les spĂ©cificitĂ©s de ce type dâoutil en terme de variation dâangle dâoutil. Par ailleurs, elle propose une formulation simplifiĂ©e de la section coupĂ©e
Biotransformation of guttiferones, Symphonia globulifera metabolites, by Bipolaris cactivora , an endophytic fungus isolated from its leaves
International audienceThe search for active microorganisms for the biotransformation of guttiferone A (1) and C (6) has been successfully undertaken from a collection of endophytic fungi of Symphonia globulifera. Of the twenty-five isolates obtained from the leaves, three are active and have been identified as Bipolaris cactivora. The products obtained are the result of xanthone cyclisation with the formation of two regioisomers among four possible and corresponding to 1,16-oxy-guttiferone and 3,16-oxy-guttiferone. The biotransformation conditions were studied. Interestingly, both oxy-guttiferones A are present in the plant, and the ratio of 3,16-oxy-guttiferone to 1,16-oxy-guttiferone is 4â:â1, very close to that observed by biotransformation (3.8â:â1). These results are consistent with the involvement of endophytes in their formation pathway from guttiferone A, in planta. Finally, biotransformation made it possible to obtain and describe for the first time oxy-guttiferones C
RÎle des microdomaines du plasmalemme dans la réponse de la cellule végétale au stress biotique
National audienc
Yeast-Mediated Xanthone Synthesis through Oxidative Intramolecular Cyclization
Benzoylphloroglucinol derivatives are natural products showing diverse biological activities that could be modulated by structural modifications. For this purpose, we studied the biotransformation of guttiferone A and of maclurin using a combinatorial approach for screening active microorganism strains. We found a novel and unexpected yeast-catalyzed oxidation that has selectively given a new oxy-guttiferone A and norathyriol
Isolation of Guttiferones from Renewable Parts of Symphonia globulifera by Centrifugal Partition Chromatography
International audienc