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Personne :
Voyer, Normand

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Voyer

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Normand

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Université Laval. Département de chimie

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ncf10177480

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Total synthesis of Crotogossamide using an on-resin concomitant cyclization/cleavage reaction

2018-05-22, Bérubé, Christopher, Borgia, Alexandre, Grenier, Daniel, Simon, Gaëlle, Voyer, Normand

Crotogossamide, a cyclic peptide isolated from the latex of Croton gossypifolius, has been synthesized by a rapid and efficient Boc solid-phase peptide synthesis. The strategy takes advantage of the oxime resin nucleophile susceptibility and comprises the synthesis of a linear precursor followed by on-resin head-to-tail concomitant cyclization/cleavage. In addition, we report the first antimicrobial and antibiofilm investigations on Crotogossamide.

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Total synthesis and antimalarial activity of mortiamides A–D

2019-05-20, Bérubé, Christopher, Gagnon, Dominic, Richard, Dave, Borgia, Alexandre, Voyer, Normand

Mortiamides A–D (1–4) are head-to-tail cyclic heptapeptides that were identified from a novel Mortierella sp. isolate obtained from marine sediments from Northern Canada. Herein we report the first total synthesis of mortiamides A–D (1–4) on a solid support by concomitant cyclization/cleavage without any oligomerization side reactions, and overall yields up to 48%. We also report on the antiplasmodial activity of mortiamides A–D (1–4). We show that three out of the four tested mortiamides (A, B and D) have moderate antiplasmodial activity, while mortiamide D (4) exhibits low micromolar activity.

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Chemical composition and antiplasmodial activity of the essential oil of rhododendron subarcticum leaves from Nunavik, Québec, ́Canada

2023-05-01, Séguin, Jean-Christophe, Gagnon, Dominic, Bélanger, Sarah, Richard, Dave, Fernandez, Xavier, Boudreau, Stéphane, Voyer, Normand

Dwarf Labrador tea, Rhododendron subarcticum Harmaja, is a popular medicinal plant in use by First Nations of Northern Canada, but its phytochemistry has remained largely unexplored. We have isolated and characterized the essential oil from a population of this species harvested near the treeline in Nunavik, Québec. Analyses by gas chromatography–mass spectrometry (GC–MS) and gas chromatography/flame-ionization detection (GC/FID) led to the identification of 53 compounds; the main secondary metabolites were ascaridole (64.7% of the total FID area) and p-cymene (21.1%). Such a composition resembles a chemotype observed for R. tomentosum, a close relative found mainly in Europe and Asia, but has never been attributed to R. subarcticum. Growth inhibition assays against different strains of Plasmodium falciparum (3D7, Dd2), the parasite responsible for the most severe form of malaria, were conducted with either the R. subarcticum’s essential oil or the isolated ascaridole. Our results show that the essential oil’s biological activity can be attributed to ascaridole as its IC50 is more than twice that of ascaridole [ascaridole’s IC50 values are 147.3 nM (3D7) and 104.9 nM (Dd2)].

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Crown-ether-modified cyclic dipeptides as supramolecular chiral catalysts

2017-10-20, Bérubé, Christopher, Voyer, Normand

With the objective to develop supramolecular catalysts for useful chemical transformations, we report here a rapid and efficient solid-phase synthesis of novel cyclic dipeptides (crown-CDPs) with a diversity of L-DOPA derived crown ether substituents and stereochemistry. We prepared and characterized 14 crown-CDPs and evaluated their efficiency as supramolecular epoxidation catalysts in a water/hexanes biphasic system. Yields increase significantly in the presence of the crown-CDPs, though enantioselectivity depends on the nature of the substituents. The results reported constitute a useful approach for chiral epoxides of interest and further illustrate the potential of cyclic peptides as supramolecular catalysts.

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Chemical composition of the unexplored volatile fraction of betula glandulosa, a prevalent shrub in Nunavik, Québec

2021-12-09, Boudreau, Stéphane, Fernandez, Xavier, Voyer, Normand, Séguin, Jean-Christophe

The volatile fraction of the leaves of Betula glandulosa Michx. has been investigated for its secondary metabolite composition by GC/MS and GC/FID. The rapid expansion of this shrub species in subarctic landscapes, like the ones found in Nunavik (Northern Québec, Canada), highly impacts ecosystem dynamics. Yet, despite its abundance, few phytochemical investigations have yet been conducted on this species. In this study, we present the first phytochemical investigation of the volatile metabolites of B. glandulosa leaves. Although no essential oil was isolated, volatile compounds were extracted from the hydrosol by steam distillation. The main metabolites observed were linalool (14.6–19.0 %), C6 oxylipins (known as green leaf volatiles, GLV; total of 18.2–40.2 %), eugenol (1.6–8.6 %) and α-terpineol (3.3–4.8 %). Dwarf birch is an important food source for insects and herbivores, so knowledge of its metabolite composition could help understand parts of its functional role in subarctic ecosystems. The composition of the volatile fraction could serve as marker for differentiating B. glandulosa from other dwarf birch species like Betula nana L.

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Crown ether modified peptide interactions with model membranes

2019-02-17, Bacon, Anne, Provencher, Marie-Ève, Auger, Michèle, Cardinal, Sébastien, Lagüe, Patrick, Collignon, Barbara, Fillion, Matthieu, Bürck, Jochen, Otis, François, Voyer, Normand, Dionne, Justine, Paquet-Côté, Pierre-Alexandre

A simple model of an uncharged antimicrobial peptide, carrying four crown ether side chains, is modified further by the selective incorporation of arginine side chains to control its secondary structure and its interaction with model membranes and living cells. Conformational studies show that shifting the position of a cationic residue in the peptide sequence allows to control its secondary structure and supramolecular self-assembly in solution. Results also demonstrate that the secondary structure influences the interaction with model membranes and cells. An α-helical peptide with greater amphiphilicity forms assemblies that interact with both prokaryotic and eukaryotic model membranes and cells. However, a β-stranded peptide with evenly distributed charges generates assemblies that interact more selectively with prokaryotic model membranes and cells. In addition, we observed differences in peptide orientation between uncharged and cationic α-helical peptides with different phospholipid bilayers. In general, the studied peptides have a higher affinity for thinner membranes, and cationic peptides interacted better with anionic membranes.

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Dibenzofurans and pseudodepsidones from the lichen stereocaulon paschale collected in Northern Quebec

2017-01-12, Azelmat, Jabrane, Ferreira Queiroz, Emerson, Boudreau, Stéphane, Marcourt, Laurence, Grenier, Daniel, Wolfender, Jean-Luc, Carpentier, Claudia, Voyer, Normand

Chemical investigation of the methanol extract of the lichen Stereocaulon paschale collected in Nunavik, Canada, led to the isolation and identification of two new dibenzofurans (1 and 3) and 11 known lichen metabolites. The structures of the new compounds were established by analysis of 1D and 2D NMR spectroscopic and high-resolution mass spectrometric data. Herein, the first isolation of ascomatic acid dibenzofuran derivatives (1–3) from a whole lichen organism is reported. In addition, some of the isolated metabolites showed antibacterial activity against the oral pathogens Porphyromonas gingivalis and Streptococcus mutans.

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Total synthesis of pseudacyclins A-E by an on-resin head-to-side chain concomitant cyclization-cleavage reaction

2018-10-16, Bérubé, Christopher, Borgia, Alexandre, Voyer, Normand

Taking advantage of the nucleophile-sensitive ester link of oxime resin, a novel synthetic strategy was applied to the first synthesis of a type of cyclic peptides known as pseudacyclins A–E. The endocyclic ornithine side-chain part was incorporated by an on-resin acid-catalyzed concomitant cyclization-cleavage reaction after a selective deprotection of orthogonally protected ornithine. The synthetic methodology gives high macrocyclization yields and low oligomerization side-products. The combination used of solid-phase/solution-phase strategy was efficient to prepare pseudacyclins and could prove useful to prepare other natural cycle-tail peptides.

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Interfacial supramolecular biomimetic epoxidation catalysed by cyclic dipeptides

2016-10-13, Barbeau, Xavier, Delcey, Nicolas, Bérubé, Christopher, Cardinal, Sébastien, Bouchard, Corinne, Lagüe, Patrick, Boudreault, Pierre-Luc, Voyer, Normand

We synthesised a library of cis- and trans-cyclic dipeptides and evaluated their efficacy as catalysts in the asymmetric Weitz-Scheffer epoxidation of trans-chalcone. A thorough investigation relying on structure-activity studies and computational studies provided insights into the mechanism of the process. Our results revealed some structural features required for efficient conversion and for introduction of chirality into the product. The cyclic dipeptide acts as a catalyst by templating a supramolecular arrangement at the aqueous-organic interface required for efficient transformations to occur. Among all cyclic dipeptides investigated, cyclo(Leu-Leu) was the most efficient supramolecular catalyst.

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Modulating the activity of membrane-active peptides through Zn(II) complexation

2017-12-13, Paradis, Jean-Philippe, Tuck, Kellie L., Voyer, Normand, Paquet-Côté, Pierre-Alexandre, Graham, Bimbil

Seeking to increase the selectivity of antimicrobial peptides for prokaryotic cells, we incorporated a bis-dipicolyl amine (bis-DPA) ligand at the N-terminus of de novo designed model peptides. The Zn2·bisDPA complex increases the interaction of peptides with anionic model membranes, while decreasing interactions with zwitterionic model membranes. Further, it improves the peptides’ antimicrobial activity and decreases their hemolytic activity without substantial changes to their secondary structure. Therefore, incorporating a Zn2·bisDPA complex is a useful strategy to enhance the selectivity of antimicrobial peptides.