Two New Retigerane-Type Sesterterpenoids from the Lichen Leprocaulon microscopicum

International audienceTwo new sesterterpenes, 1 and 2, have been isolated from the lichen Leprocaulon microscopicum. In addition to classic chromatographic methods, a liquid-liquid chromatography technique, namely centrifugal partition chromatography (CPC) was applied for the purification of compound 2. The structures were determined by analyses of mass spectrometry and 1D- and 2D-NMR data. The relative configuration of the isolated compounds was assigned on the basis of 2D-NOESY experiments. The two compounds possess a rare pentacyclic carbon skeleton typical for lichen metabolism, and quite unusual in the vegetal kingdom

Evolution of defects in Ti6-4 under Ti2+ ion irradiation: Focus on radiation-induced precipitates

Ion irradiations on the Ti6-4 titanium alloy were conducted at the JANNUS French platform in two different conditions of temperatures, doses and fluxes, to simulate neutron irradiation damage. Quantification of defects and chemical microanalyses were carried out thanks to Transmission Electron Microscopy and Atom Probe Tomography. -type loops and radiation induced precipitates (a vanadium-rich β BCC phase) were observed for both irradiation temperatures. During an irradiation at 300 °C, there was no notable influence of the dose and flux for the considered doses and fluxes ranges on the -type defects. The influence of raising the irradiation temperature up to 430 °C was a lowering of their density and an increase of their mean diameter for both defects. In addition, a lower flux seemed to enhance this temperature effect. These phenomena were very significant for precipitates whereas it appeared very modest for -type loops. The probable mechanism to explain the distribution of vanadium-rich β precipitates inside the α phase is the heterogeneous nucleation. The nucleation is dominated by the Radiation Induced Segregation (RIS) phenomenon at 430 °C and could be dominated by the mechanism of vanadium-rich clusters formation by ballistic effects in the cascades at 300 °C

Leishmaniose viscérale et maladie du sommeil (étude chimique bioguidée d'une annonaceae ivoirienne, Uvaria afzelii)

BESANCON-BU Médecine pharmacie (250562102) / SudocSudocFranceF

Evolution de la prise en charge du cancer du sein

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Étude phytochimique de trois lichens crustacés du littoral breton (Ochrolechia parella, Tephromela atra et Diploicia canescens)

L étude phytochimique de trois lichens saxicoles du littoral breton: Ochrolechia parella, Tephromela atra et Diploicia canescens a permis d isoler et de caractériser 25 composés issus du métabolisme secondaire. Ces lichens ont été choisis en fonction de leur habitat et sélectionnés lors d un criblage préliminaire permettant de repérer les composés absorbant dans le domaine des UVB (280-320 nm) et/ou des UVA (320-400 nm). Trois de ces produits ont été identifiés pour la première fois à partir d une source naturelle. Diverses évaluations biologiques menées sur les produits isolés en quantité suffisante, ont permis d apprécier leur cytotoxicité in vitro où de révéler d autres potentialités (activité antioxydante, induction de la mélanogénèse). Deux depsidones et une bisxanthone s avèrent être des molécules d intérêt dans le domaine de la photoprotection: l acide variolarique, la diploicine et l acide sécalonique B.A phytochemical study of three saxicolous lichens from the Brittany seashore: Ochrolechia parella, Tephromela atra and Diploicia canescens led to the isolation and structural elucidation of 25 secondary metabolites. These lichens were chosen regarding their environmental situation and after a preliminary screening which allowed us to select compounds absorbing in the UVA (320-400 nm) and/or in the UVB (280-320 nm) range. Most of the isolated compounds were depsidones, some of them halogenated. Various biological evaluations carried out on the products isolated in sufficient amount, permitted to quantify their in vitro cytotoxicity and other activities (antioxidant activity, tyrosinase inhibition, melanogenesis induction). Two depsidones, variolaric acid and diploicin as so as a bisxanthone, secalonic B acid appeared to be valuable compounds to investigate further in the photoprotective domain.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Introduction

International audienc

Introduction

International audienc

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