Meroditerpene from Cystoseira nodicaulis and its taxonomic significance

International audienceThe first investigations carried out on the lipophilic content of samples of the brown alga, Cystoseira nodicaulis, collected along the Atlantic coasts of France led to the isolation of a single monocyclic meroditerpene previously identified in Cystoseira elegans. This finding supplements the chemical data available about the Sargassaceae family and opens the way to further discussions about taxonomy through comparisons with phylogenetic studies. Cyclized meroditerpenes are a typical feature of the clade that includes C. nodicaulis and its allied species C. elegans and Cystoseira baccata

LC/ESI-MSn and 1H HR-MAS NMR analytical methods as useful taxonomical tools within the genus Cystoseira C. Agardh (Fucales; Phaeophyceae)

International audienceSpecies of the genus Cystoseira are particularly hard to discriminate, due to the complexity of their morphology, which can be influenced by their phenological state and ecological parameters. Our study emphasized on the relevance of two kinds of analytical tools, (1) LC/ESI-MSn and (2) 1H HR-MAS NMR, also called in vivo NMR, to identify Cystoseira specimens at the specific level and discuss their taxonomy. For these analyses, samples were collected at several locations in Brittany (France), where Cystoseira baccata, C. foeniculacea, C. humilis, C. nodicaulis and C. tamariscifolia were previously reported. To validate our chemical procedure, the sequence of the ITS2 has been obtained for each species to investigate their phylogenetic relationships at a molecular level. Our study highlighted the consistency of the two physico-chemical methods, compared to "classical" molecular approach, in studying taxonomy within the genus Cystoseira. Especially, LC/ESI-MSn and phylogenetic analyses converged into the discrimination of two taxonomical groups among the 5 species. The occurrence of some specific signals in the 1H HR-MAS NMR spectra and/or some characteristic chemical compounds during LC/ESI-MSn analysis could be regarded as discriminating factors. LC/ESI-MSn and 1H HR-MAS NMR turned out to be two relevant and innovative techniques to discriminate taxonomically this complex genus

NMR use to quantify phlorotannins: The case of Cystoseira tamariscifolia, a phloroglucinol-producing brown macroalga in Brittany (France)

International audienceAmong the most renowned natural products from brown algae, phlorotannins are phloroglucinol polymers that have been extensively studied, both for their biotechnological potential and their interest in chemical ecology. The accurate quantification of these compounds is a key point to understand their role as mediators of chemical defense. In recent years, the Folin-Ciocalteu assay has remained a classic protocol for phlorotannin quantification, even though it frequently leads to over-estimations. Furthermore, the quantification of the whole pool of phlorotannins may not be relevant in ecological surveys. In this study, we propose a rapid 1H qNMR method for the quantification of phlorotannins. We identified phloroglucinol as the main phenolic compound produced by the brown macroalga Cystoseira tamariscifolia. This monomer was detected in vivo using 1H HR-MAS spectroscopy. We quantified this molecule through 1H qNMR experiments using TSP as internal standard. The results are discussed by comparison with a standard Folin-Ciocalteu assay performed on purified extracts. The accuracy and simplicity of qNMR makes this method a good candidate as a standard phlorotannin assay

New insights into the haemo‐ and coelo‐microbiota with antimicrobial activities from Echinodermata and Mollusca

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Antimicrobial Peptides from Marine Proteobacteria

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Extraction and Purification of Phlorotannins from Brown Algae

International audienceThe interest in the physiological roles and bioactivities of plant phenols has increased over the past decades. In seaweeds, many investigations have dealt with phenolic compounds of Phaeophyceae (phlorotannins), even though little is known so far about the ecophysiological variations of their pool or their biosynthetic pathways. We describe here a simple procedure based on the use of water-organic solvent mixtures for the extraction of phlorotannins. Crude extracts are semi-purified and fractionated by separating methods based on both the polarity and the molecular size of compounds. Phenols are then quantified by the Folin-Ciocalteu method and their radical-scavenging activity is characterized using the DPPH test. All along the purification process of phenolic compounds, the efficiency of separation is assessed by 1H-NMR

Spotlight on Antimicrobial Metabolites from the Marine Bacteria Pseudoalteromonas: Chemodiversity and Ecological Significance

International audienceThis review is dedicated to the antimicrobial metabolite-producing Pseudoalteromonas strains. The genus Pseudoalteromonas hosts 41 species, among which 16 are antimicrobial metabolite producers. To date, a total of 69 antimicrobial compounds belonging to 18 different families have been documented. They are classified into alkaloids, polyketides, and peptides. Finally as Pseudoalteromonas strains are frequently associated with macroorganisms, we can discuss the ecological significance of antimicrobial Pseudoalteromonas as part of the resident microbiota

À la découverte des métiers de la recherche en imagerie cérébrale

National audienceQue connaissez-vous sur la recherche sur le cerveau et sur ces acteurs ? Des chercheurs de l’équipe Empenn* vous présentent leurs métiers et leurs travaux de recherche sous forme d’un grand quiz. Question ? Réponses ! Et surtout discussion.Venez en apprendre plus sur le cerveau, l’imagerie et la recherche

À la découverte des métiers de la recherche en imagerie cérébrale

National audienceQue connaissez-vous sur la recherche sur le cerveau et sur ces acteurs ? Des chercheurs de l’équipe Empenn* vous présentent leurs métiers et leurs travaux de recherche sous forme d’un grand quiz. Question ? Réponses ! Et surtout discussion.Venez en apprendre plus sur le cerveau, l’imagerie et la recherche

Deep Subseafloor Fungi as an Untapped Reservoir of Amphipathic Antimicrobial Compounds

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