Marseille, France


Marseille, France
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Laurencon L.,University of Nice Sophia Antipolis | Sarrazin E.,University of Nice Sophia Antipolis | Chevalier M.,University of Nice Sophia Antipolis | Precheur I.,University of Nice Sophia Antipolis | And 3 more authors.
Phytochemistry | Year: 2013

As part of research for treatments to combat oral dryness, our evaluation of the activity of an aqueous extract of Solidago virgaurea (L.) ssp. alpestris (Asteraceae) revealed activity against Candida albicans hyphae, the pathogenic form of this yeast. Systematic bioassay-guided fractionation of this extract gave an active saponin-containing fraction from which six oleanane-type triterpenoid saponins were isolated. Three of these were isolated for the first time, as 3-O-(β-d-glucopyranosyl-(1 → 3)-β-d-glucopyranosyl)-28- O-(β-d-fucopyranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-β-d-xylopyranosyl)-polygalacic acid (virgaureasaponin 4), 3-O-(β-d-glucopyranosyl)-28-O-(β-d-fucopyranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-β-d-xylopyranosyl)-polygalacic acid (virgaureasaponin 5) and 3-O-(β-d-glucopyranosyl)-28-O-(α-l- rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-[5-O-acetylapiofuranosyl-(1 → 3)-[4-O-(3-(3-hydroxy-1-oxobutoxy)-1-oxobutyl)]-β-d-fucopyranosyl] -polygalacic acid (virgaureasaponin 6). Their structures were established by carrying out 1D and 2D NMR experiments along with HRMS analyses. All of the six saponins were evaluated to ascertain their inhibition of C. albicans yeast-hyphal conversion, and four of them showed significant inhibition. © 2012 Elsevier Ltd. All rights reserved.

Liu X.,Wuhan University | Liu X.,CNRS Interdisciplinary Nanoscience Centre of Marseille | Chen H.,Wuhan University | Laurini E.,University of Trieste | And 9 more authors.
Organic Letters | Year: 2011

2-Difluoromethylene-4-methylenepentanoic acid (DFMPA), a seemingly deviated analog of 2-oxoglutaric acid (2-OG), could surprisingly mimic its signaling function in cyanobacteria. Computer modeling revealed the favorable binding of DFMPA toward the 2-OG receptor, NtcA, via mutual conformational changes, suggesting that structural alteration of 2-OG is tolerated for it to exercise its signaling role. This extremely useful finding could be exploited for the design of affinity probes with which to study new 2-OG receptors in related signaling pathways. © 2011 American Chemical Society.

Reynaud C.,CNRS Chemistry Laboratory | Giorgi M.,Spectropole | Doucet H.,CNRS Chemistry Institute of Rennes | Santelli M.,CNRS Chemistry Laboratory
Synthesis | Year: 2011

The Diels-Alder reaction of spirobicyclic cyclopentadiene derivatives, prepared by reaction of cyclopentadienyllithium and epichlorohydrin, with maleic anhydride gave a simple access to spiro tricyclic polyoxygenated compounds of synthetic interest. The solvolytic behavior of 1-(tosyloxymethyl)spiro[2.4] hepta-4,6-diene, a 5-spirocyclopentadiene, shows that the ionization of the tosylate was unlikely. © 2010 Georg Thieme Verlag Stuttgart New York.

Liu X.,Aix - Marseille University | Liu X.,Wuhan University | Wang Y.,Aix - Marseille University | Wang Y.,Wuhan University | And 10 more authors.
Organic Letters | Year: 2013

A 2-oxoglutaric acid (2-OG) probe bearing a methylene group introduced at the C4 position and a vinyl group to replace the carbonyl group at the C2 position elicited characteristic affinity for NtcA, the 2-OG receptor, while maintaining the signaling function of the parent natural metabolite 2-OG. This discovery opens new perspectives in the design, synthesis, and implementation of specific 2-OG analogues as molecular probes for investigating the complex 2-OG signaling pathways. © 2013 American Chemical Society.

Guenon R.,CNRS Microbial Ecology | Vennetier M.,IRSTEA | Dupuy N.,CNRS Institute of Molecular Sciences of Marseilles | Ziarelli F.,Spectropole | Gros R.,CNRS Microbial Ecology
Applied Soil Ecology | Year: 2011

The principal aim of this research was to determine the influence of an increasing wildfire history on the recovery at short and long term of soil organic matter (SOM) composition and microbial properties. The contemporary wildfire events (since 1950) were recorded for 27 plots located on the siliceous part of the French Mediterranean region (Maures mountain ranges). A wildfire history index was built, tested and calculated in order to display numerical values representative of the different wildfire history parameters (i.e. number of fires, time since fire and mean fire interval). Microbial basal respiration and biomass were analysed as well as intensity of the use of 31 C-substrates, catabolic diversity and C-substrates utilisation profiles. Furthermore, a qualitative characterisation of the SOM was carried out by solid state 13C NMR. Potential drivers of the microbial recovery were identified by studying the relationships between microbial activities and chemical functions of SOM. Our results showed that fire histories resulting in considerable losses or alterations of SOM, such as recent or close fires, decreased the microbial catabolic evenness. This could be attributed to a preferential utilisation of N-containing compounds and complex substrates such as aromatic and polymers reflecting a greater N microbial demand and a selection of specific catabolic functions. Moreover, a large number of fires (4 fires in 57 years compared to 1-2) resulted in lasting degradation of the relative intensity of methyl C function in polymethylene, O-Alkyl C, aromatic C and phenolic C functions inducing a slow-down in recovery of microbial properties. These results also confirm our hypothesis that some chemical functions of SOM can be in equilibrium with wildfire history. Finally, this research demonstrates that FT-NIR analysis can be used as a valuable tool to assess both the wildfire history and the vulnerability of soil quality to shifts in historical fire regimes. © 2011 Elsevier B.V.

Campolo D.,Aix - Marseille University | Arif T.,Aix - Marseille University | Borie C.,Aix - Marseille University | Mouysset D.,Aix - Marseille University | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2014

An original synthesis of chiral benzofulvenes triggered by organocopper reagents is reported. These enantiopure products are available through a highly chemo-, regio-, diastereo-, and enantioselective bis(alkylating) cycloisomerization process. A double chirality transfer (central-to-axial-to- central) is observed. Double duty: An original synthesis of chiral benzofulvenes was developed through the highly chemo-, regio-, diastereo-, and enantioselective double transfer of alkyl groups to electrophilic enediynes. This organocopper-triggered cycloisomerization proceeds with double transfer of chirality (central-to-axial-to-central). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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