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
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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Falkowski, M., et al. "Assessment of A Simple Compound-Saving Method to Study Insecticidal Activity of Natural Extracts and Pure Compounds Against Mosquito Larvae." Journal of the American Mosquito Control Association. 32.4 (2016): 337–340.
Abstract: Research on natural insecticides has intensified with the spread of resistance to chemicals among insects, particularly disease vectors. To evaluate compounds, the World Health Organization (WHO) has published standardized procedures. However, those may be excessively compound-consuming when it comes to assessing the activity of natural extracts and pure compounds isolated in limited amount. As part of our work on the discovery of new mosquito larvicides from Amazonian plants, we developed a compound-saving assay in 5-ml glass tubes instead of WHO larval 100-ml cups. Comparing activity of synthetic and natural chemicals validated the glass tube assay. Raw data, lethal doses that kill 50% (LD50) and 90% (LD90) at 24 and 48 h, were highly correlated (0.68 < R2 < 0.96, P < 0.001, Pearson test) between cups and tubes. It was also established that 10 tubes (N = 50 larvae) provided the same level of sensitivity as 20 tubes (N = 100). This method proved suitable for rapid screening of natural extracts and molecules, identifying active compounds using 10 times less material than in the WHO protocol. © 2016 by The American Mosquito Control Association, Inc.
Keywords: Mosquitoes; natural insecticides; screening method
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Odonne, G., et al. "Treating leishmaniasis in Amazonia: A review of ethnomedicinal concepts and pharmaco-chemical analysis of traditional treatments to inspire modern phytotherapies." Journal of Ethnopharmacology. 199 (2017): 211–230.
Abstract: Ethnopharmacological relevance Cutaneous and mucocutaneous leishmaniasis are neglected tropical diseases that occur in all intertropical regions of the world. Amazonian populations have developed an abundant knowledge of the disease and its remedies. Therefore, we undertook to review traditional antileishmanial plants in Amazonia and have developed new tools to analyze this somewhat dispersed information. Material and methods A literature review of traditional remedies for cutaneous/mucocutaneous leishmaniasis in the Amazon was conducted and the data obtained was used to calculate distribution indexes designed to highlight the most relevant uses in Amazonia. The cultural distribution index represents the distribution rate of a given taxon among different cultural groups and was calculated as the ratio of the number of groups using the taxon to the total number of groups cited. The geographical distribution index allowed us to quantify spatial distribution of a taxon's uses in Amazonia and was calculated geometrically by measuring the average distance between the points where uses have been reported and the barycenter of those points. The general distribution index was defined as an arithmetic combination of the previous two and provides information on both cultural and spatial criteria. Results 475 use reports, concerning 291 botanical species belonging to 83 families have been gathered depicted from 29 sources. Uses concern 34 cultural groups. While the use of some taxa appears to be Pan-Amazonian, some others are clearly restricted to small geographical regions. Particular attention has been paid to the recipes and beliefs surrounding treatments. Topical application of the remedies dominated the other means of administration and this deserves particular attention as the main treatments against Neotropical leishmaniasis are painful systemic injections. The data set was analyzed using the previously defined distribution indexes and the most relevant taxa were further discussed from a phytochemical and pharmacological point of view. Conclusions The Amazonian biodiversity and cultural heritage host a fantastic amount of data whose systematic investigation should allow a better large-scale understanding of the dynamics of traditional therapies and the consequent discovery of therapeutic solutions for neglected diseases. Distribution indices are indeed powerful tools for emphasizing the most relevant treatments against a given disease and should be very useful in the meta-analysis of other regional pharmacopeia. This focus on renowned remedies that have not yet benefitted from extended laboratory studies, could stimulate future research on new treatments of natural origin for leishmaniasis. © 2017 Elsevier Ireland Ltd
Keywords: Amazonia; Distribution indexes; Ethnomedecine; Interculturality; Leishmaniasis; Medicinal plants; Traditional medicine
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