Tél. : (+594) 5 94 29 31 34
email : Emeline.Houel at EcoFoG.gf
Position
Research Engineer at UMR EcoFoG.
Research
Functional role and valorization of specialized metabolites of plant origin: chemical properties of wood within the tree in relation to its environment, botanical insecticides.
Academic background
- 2020 Qualification to supervise research (« Habilitation à diriger des recherches »), Université de Guyane : « Natural products chemistry in the Amazon: “human chemical defenses” - Diversity, interactions, inspiration »
- 2011 PhD in chemistry, Université des Antilles et de la Guyane : « Study of bioactive compounds from the Amazonian flora »
- 2003 Master’s degree in engineering, ENSCM (National Higher School of Chemistry, Montpellier)
Ongoing research programs
TREE-D
SEXTONIAEDES
Publications for EcoFoG
Diatta, Bétémondji Désiré, et al. "Diversité et composition phytochimique des bâtonnets frotte-dents (cure-dents) proposés chez les Peul de la commune de Tessékéré (Ferlo Nord, Sénégal)." Journal of Applied Biosciences. 158 (2021): 16267–16281.
Abstract: Objectifs : Le but de cette étude était de déterminer la composition phytochimique et la teneur en grandes classes chimiques des tiges les plus utilisées comme bâtonnets frotte-dents chez les peul de Widou Thiengoli au Nord Ferlo (Sénégal). Méthodes et résultats : Des entretiens ouverts semi structurés ont permis de recueillir les plantes les plus utilisées. L’indice de fidélité renseigne sur la convergence des usages quant à l’emploi des plantes comme bâtonnets frotte-dent comparé aux autres pratiques cosmétiques. L’étude de la composition phytochimique des tiges a ciblé 8 classes chimiques. Les tanins et les saponines sont très fréquents ; les terpénoïdes et les leuco-anthocyanines presque inexistants. Un dosage des flavonoïdes, alcaloïdes et polyphénols, réalisé chez des extraits aqueux, a porté sur 12 plantes. Les meilleures teneurs en polyphénols et alcaloïdes sont recueillies chez Anogeissus leiocarpa, et la meilleure en flavonoïdes chez Commiphora africana. Conclusion et applicabilité des résultats : Ces résultats permettent de sélectionner à travers la composition phytochimique des plantes, les espèces présentant de potentielles activités antimicrobiennes, car renfermant des composés phytochimique doués de fonctions germicides, au- delà de la fonction mécanique connue des bâtonnets dans l’élimination de la plaque dentaire.
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Heu, Katy, et al. "The Effect of Secondary Metabolites Produced by Serratia marcescens on Aedes aegypti and Its Microbiota." Frontiers in Microbiology. 12 (2021): 645701.
Abstract: Serratia marcescens is a bacterial species widely found in the environment, which very efficiently colonizes mosquitoes. In this study, we isolated a red-pigmented S. marcescens strain from our mosquito colony (called S. marcescens VA). This red pigmentation is caused by the production of prodigiosin, a molecule with antibacterial properties. To investigate the role of prodigiosin on mosquito- S. marcescens interactions, we produced two white mutants of S. marcescens VA by random mutagenesis. Whole genome sequencing and chemical analyses suggest that one mutant has a nonsense mutation in the gene encoding prodigiosin synthase, while the other one is deficient in the production of several types of secondary metabolites including prodigiosin and serratamolide. We used our mutants to investigate how S. marcescens secondary metabolites affect the mosquito and its microbiota. Our in vitro tests indicated that S. marcescens VA inhibits the growth of several mosquito microbiota isolates using a combination of prodigiosin and other secondary metabolites, corroborating published data. This strain requires secondary metabolites other than prodigiosin for its proteolytic and hemolytic activities. In the mosquito, we observed that S. marcescens VA is highly virulent to larvae in a prodigiosin-dependent manner, while its virulence on adults is lower and largely depends on other metabolites
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Fu, T., et al. "Biosynthetic investigation of γ-lactones in Sextonia rubra wood using in situ TOF-SIMS MS/MS imaging to localize and characterize biosynthetic intermediates." Sci. Rep.. 9 (2019): 1928.
Abstract: Molecular analysis by parallel tandem mass spectrometry (MS/MS) imaging contributes to the in situ characterization of biosynthetic intermediates which is crucial for deciphering the metabolic pathways in living organisms. We report the first use of TOF-SIMS MS/MS imaging for the cellular localization and characterization of biosynthetic intermediates of bioactive γ-lactones rubrynolide and rubrenolide in the Amazonian tree Sextonia rubra (Lauraceae). Five γ-lactones, including previously reported rubrynolide and rubrenolide, were isolated using a conventional approach and their structural characterization and localization at a lateral resolution of ~400 nm was later achieved using TOF-SIMS MS/MS imaging analysis. 2D/3D MS imaging at subcellular level reveals that putative biosynthetic γ-lactones intermediates are localized in the same cell types (ray parenchyma cells and oil cells) as rubrynolide and rubrenolide. Consequently, a revised metabolic pathway of rubrynolide was proposed, which involves the reaction between 2-hydroxysuccinic acid and 3-oxotetradecanoic acid, contrary to previous studies suggesting a single polyketide precursor. Our results provide insights into plant metabolite production in wood tissues and, overall, demonstrate that combining high spatial resolution TOF-SIMS imaging and MS/MS structural characterization offers new opportunities for studying molecular and cellular biochemistry in plants. © 2019, The Author(s).
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Fu, T., et al. "Tandem Mass Spectrometry Imaging and in Situ Characterization of Bioactive Wood Metabolites in Amazonian Tree Species Sextonia rubra." Anal. Chem.. 90.12 (2018): 7535–7543.
Abstract: Driven by a necessity for confident molecular identification at high spatial resolution, a new time-of-flight secondary ion mass spectrometry (TOF-SIMS) tandem mass spectrometry (tandem MS) imaging instrument has been recently developed. In this paper, the superior MS/MS spectrometry and imaging capability of this new tool is shown for natural product study. For the first time, via in situ analysis of the bioactive metabolites rubrynolide and rubrenolide in Amazonian tree species Sextonia rubra (Lauraceae), we were able both to analyze and to image by tandem MS the molecular products of natural biosynthesis. Despite the low abundance of the metabolites in the wood sample(s), efficient MS/MS analysis of these γ-lactone compounds was achieved, providing high confidence in the identification and localization. In addition, tandem MS imaging minimized the mass interferences and revealed specific localization of these metabolites primarily in the ray parenchyma cells but also in certain oil cells and, further, revealed the presence of previously unidentified γ-lactone, paving the way for future studies in biosynthesis.
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Touré, S., et al. "Aedes aegypti Larvicidal Sesquiterpene Alkaloids from Maytenus oblongata." Journal of Natural Products. 80.2 (2017): 384–390.
Abstract: Four new sesquiterpene alkaloids (1-4) with a β-dihydroagrofuran skeleton and a new triterpenoid (5) were isolated from an ethyl acetate extract of Maytenus oblongata stems. Their structures were elucidated using 1D and 2D NMR spectroscopy as well as MS and ECD experiments. The M. oblongata stem EtOAc extract and the pure compounds isolated were tested for larvicidal activity against Aedes aegypti under laboratory conditions, and compounds 2 and 3 were found to be active. © 2017 The American Chemical Society and American Society of Pharmacognosy.
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Emeline Houël