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See detailDes liposomes contre la malaria
Ledoux, Allison ULiege

Article for general public (2019)

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See detailÉtude des potentialités antiplasmodiales de plantes endémiques des Mascareignes: Poupartia borbonica Gmel., une nouvelle source de composés antimalariques prometteurs ?
Ledoux, Allison ULiege

Doctoral thesis (2019)

Ce travail de thèse a été mené dans l’optique de participer à la recherche de nouveaux antipaludiques provenant de plantes endémiques des Mascareignes. La première partie de ce travail est consacrée au ... [more ▼]

Ce travail de thèse a été mené dans l’optique de participer à la recherche de nouveaux antipaludiques provenant de plantes endémiques des Mascareignes. La première partie de ce travail est consacrée au criblage antiplasmodial in vitro réalisé sur 64 plantes provenant de l’île de la Réunion. Ces plantes ont été sélectionnées selon plusieurs critères : leurs endémismes, leurs usages traditionnels, ainsi que leurs inscriptions à la Pharmacopée. L’objectif principal de cette partie du travail consistait à mettre en évidence les plantes présentant une activité antiplasmodiale prometteuse (IC50 < 15µg/mL). Parallèlement, le second objectif était de valoriser la flore locale. Plusieurs plantes se sont avérées être intéressantes : le Casearia coriaceae, le Poupartia borbonica et le Vernonia fimbrillifera dont les IC50 sont inférieures à 10 µg/mL. Le Poupartia borbonica a été sélectionné en vue de réaliser des tests phytochimiques et pharmacologiques approfondis. La deuxième partie du travail est consacrée à l’exploration phytochimique et pharmacologique de cette plante endémique. Un fractionnement bioguidé a été entrepris et a conduit à la mise en évidence de trois nouveaux composés, des dérivés d’alkylcyclohexenones, les poupartones A, B, et C. Ces trois molécules présentent une activité antiplasmodiale prometteuse (IC50<2 µM). La poupartone majoritaire, la poupartone A, a été testée in vivo sur un modèle murin. Son potentiel antipaludique a été confirmé, puisqu’une dose de 15 mg/kg a permis une réduction de la parasitémie de presque 70%, 7 jours après l’infection. Cependant, une certaine toxicité a été observée. La troisième partie de cette thèse a consisté à mettre en évidence des pistes quant aux mécanismes de toxicité liés aux poupartones. Des tests sur larves de Zebrafish exprimant une fluorescence vasculaire ou une fluorescence musculaire ont permis de mettre en évidence qu’une toxicité cardiaque semblait être une conséquence d’un mauvais état général. L’atteinte la plus rapide et la plus marquée, sur toutes larves confondues, était liée à une toxicité de contact importante. Des tests de toxicité cellulaire réalisés avec des techniques d’imagerie en temps réel sur deux lignées cellulaires ont mis en évidence une hétérogénéité d’action. Cependant, la poupartone B induit des modifications importantes de l’adhésion cellulaire, ainsi que des mécanismes de type apoptotique. La dernière partie de ce travail a eu pour principal objectif de neutraliser cette toxicité périphérique en ciblant spécifiquement les globules rouges parasités par P. falciparum. Des liposomes contenant la poupartone B ont été réalisés, ceux-ci ont été entourés d’héparine, connue pour lier spécifiquement certaines protéines exprimées par les globules rouges infectés. Des tests réalisés sur larves de Zebrafish ont démontré une diminution de la toxicité, et les tests réalisés sur P. falciparum ont établi que l’activité était améliorée, même sur les Plasmodium partiellement résistants à l’artémisinine.   [less ▲]

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See detailFlavonoid Analysis and Antioxidant Activities of the Bryonia alba L. Aerial Parts
Ielciu, Irina; Frederich, Michel ULiege; Hanganu, Daniela et al

in Antioxidants (2019), 8(4 108),

Bryonia alba L. is the only Bryonia species found in Romanian flora, being known as a remedy for inflammatory pathologies or for its hepatoprotective and adaptogen activities. The present investigation ... [more ▼]

Bryonia alba L. is the only Bryonia species found in Romanian flora, being known as a remedy for inflammatory pathologies or for its hepatoprotective and adaptogen activities. The present investigation studied the flavonoid composition and antioxidant activities of the aerial parts of this species. Flavonoid profile was evaluated by HPLC coupled with Diode Array Detection (DAD), while antioxidant capacity was assessed by various methods, testing different antioxidant mechanisms: DPPH (2,2-diphenyl-1-picrylhydrazyl), CUPRAC (cupric reducing antioxidant capacity), FRAP (ferric reducing ability of plasma), TEAC (Trolox equivalent antioxidant capacity), EPR (electron paramagnetic resonance method) and SNPAC (silver nanoparticles antioxidant capacity). Cytotoxicity was tested on human cancerous and healthy cell lines. Anti-plasmodial tests were performed on two strains of Plasmodium falciparum. Whole organism toxicity was assessed on zebrafish larvae. The HPLC-DAD analysis proved the presence of lutonarin, saponarin, isoorientin, and isovitexin as the major flavonoids in the composition of tested samples. Significant results were obtained for all antioxidant capacity assays. The cytotoxicity tests proved the absence of cellular and parasitic toxicity and these results were confirmed by the lack of toxicity on the zebrafish larvae model. This study proves a promising potential of the aerial parts of Bryonia alba L. as antioxidant agents. [less ▲]

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See detailPreparation of ellagic acid derivatives through a total synthesis approach to improve bioavailability.
Degotte, Gilles ULiege; Halleux, Annabelle; Hans, Aurore et al

Poster (2018, December)

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See detailAntimalarial and antitrypanosomal activity of strychnogucine B, a bisindole alkaloid from Strychnos icaja
Beaufay, Claire; Ledoux, Allison ULiege; Frederich, Michel ULiege et al

Poster (2018, July)

Strychnogucine B, a bisindole alkaloid isolated from Strychnos icaja (Loganiaceae), showed promising in vitro antiplasmodial properties (IC50 < 1μM) in previous studies [1, 2]. In order to obtain ... [more ▼]

Strychnogucine B, a bisindole alkaloid isolated from Strychnos icaja (Loganiaceae), showed promising in vitro antiplasmodial properties (IC50 < 1μM) in previous studies [1, 2]. In order to obtain sufficient quantities to further investigate its antiprotozoal activity, this compound was synthesized in four steps from (-)-strychnine [3]. The in vivo antimalarial activity of this semi-synthetic strychnogucine B (30 mg/kg/d, i.p) was determined in a Plasmodium berghei murine model using the Peters’ 4-day suppressive test. This alkaloid confirmed a promising antimalarial activity in vivo by suppressing the parasitaemia by almost 36 percent on day 5 and 60 percent on day 7 compared to vehicle treated mice. In addition to this interesting antiplasmodial potential, it also showed a moderate in vitro anti-trypanosomal activity (IC50 = 2.7μM) but no in vivo activity in an acute Trypanosoma brucei model. It was also inactive in vitro on Leishmania mexicana promastigotes. This study highlights the selective antiplasmodial efficacy of strychnogucine B and warrants further investigations to assess the potential of this alkaloid as new antimalarial lead compound. [less ▲]

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See detailAntiplasmodial, Anti-chikungunya virus and Antioxidant Activities of 64 endemic Plants from the Mascarene Islands.
Ledoux, Allison ULiege; Cao, Martine ULiege; Jansen, Olivia ULiege et al

in International Journal of Antimicrobial Agents (2018), 52(5), 622-628

Vector-borne diseases cause more than 1 million deaths annually. The research of new medicines is urgent, especially since there is currently no specific treatment. In this study, the authors have ... [more ▼]

Vector-borne diseases cause more than 1 million deaths annually. The research of new medicines is urgent, especially since there is currently no specific treatment. In this study, the authors have selected 64 endemic plants from the Mascarene Islands based on their endemism, their medicinal use and their registration in the French Pharmacopeia to evaluate the antiplasmodial, anti-chikungunya and antioxidant activities. The list of these 64 plants including their local name, population, data of collection and voucher number are available in the Supporting Information section. 40 active extracts have been identified from the 38 species: 22 responded positively to the antiplasmodial activity, 8 to the anti-chikungunya activity and 8 to the antioxidant activity. Six plants demonstrated high antiplasmodial activity (IC50 < 15 microg/mL): Casearia coriaceae, Monimia rotundifolia, Poupartia borbonica, Psiadia retusa, Vernonia fimbrillifera, and Zanthoxylum heterophyllum; and five showed high anti-chikungunya activity (IC50 < 20 microg/mL): Aphloia theiformis, Stillingia lineata, Croton mauritianus, Indigofera ammoxylum, and Securinega durissima. Eight plants displayed an important antioxidant activity, with values of ABTS, FRAP or ORAC > 2000 microM of Trolox equivalent per mg/mL of extract: Bertiera borbonica, Erythroxylon laurifolium, Erythroxylon sideroxyloides, Indigofera ammoxylum, Poupartia borbonica, Scolopia heterophylla, Sophora denudata, and Terminalia bentzoe. Some data obtained tend to corroborate with the reported traditional use of the plant, such as Zanthoxylum heterophyllum (antiplasmodial), Aphloia theiformis (anti-chikungunya), and Erythroxylon laurifolium (antioxidant). [less ▲]

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See detailIn vivo antimalarial and antitrypanosomal activity of strychnogucine B, a bisindole alkaloid from Strychnos icaja.
Beaufays, Claire; Ledoux, Allison ULiege; Jansen, Olivia ULiege et al

in Planta Medica (2018), 84

Strychnogucine B is a bisindole alkaloid previously isolated from Strychnos icaja that possesses promising in vitro antiplasmodial properties. This compound was synthesized in four steps from (− ... [more ▼]

Strychnogucine B is a bisindole alkaloid previously isolated from Strychnos icaja that possesses promising in vitro antiplasmodial properties. This compound was synthesized in four steps from (−)-strychnine. As no acute toxicity was observed at the highest tested cumulative dose of 60 mg/kg, its in vivo antimalarial activity was determined intraperitoneally at 30mg/kg/d in a Plasmodium berghei murine model. In the Petersʼs 4-d suppressive test, this alkaloid suppressed the parasitaemia by almost 36% on day 5 and 60% on day 7 compared to vehicle-treated mice. In addition to this interesting antimalarial activity, it showed moderate in vitro antitrypanosomal activity but no in vivo activity in an acute Trypanosoma brucei model. It was also inactive in vitro on Leishmania mexicana promastigotes. This highlights its selective antimalarial efficacy and leads to further investigation to assess its potential as new antimalarial lead compound. [less ▲]

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See detailIn vitro antiplasmodial and cytotoxic activities of sesquiterpene lactones from Vernonia fimbrillifera Less. (Asteraceae)
Bordignon, Annélise ULiege; Frederich, Michel ULiege; Ledoux, Allison ULiege et al

in Natural Product Research (2017)

According to the World Health Organization (WHO 2016 WHO. 2016. World Malaria report 2016 [Internet]; [cited 2016 Dec 20]. Available from: https://www.who.int/malaria/publications/world-malaria-report ... [more ▼]

According to the World Health Organization (WHO 2016 WHO. 2016. World Malaria report 2016 [Internet]; [cited 2016 Dec 20]. Available from: https://www.who.int/malaria/publications/world-malaria-report-2016/report/en/ [Google Scholar] ), malaria caused at least 429 000 deaths globally in 2015. Among these, 70% were children under the age of five and 99% were due to the parasite species Plasmodium falciparum. The fight against this major public health problem is threatened by the rapid emergence and spread of parasite strains resistant towards available approved treatments. Urgent efforts are therefore needed to identify new antimalarial drugs. As such, our research groups decided to study Reunion Island as a potential source for the discovery of new antiplasmodial metabolites. This natural patrimony has been identified as a biodiversity hotspot due to its numerous endemic species and its preserved ecosystems (Myers et al. 2000 Myers N, Mittermeier RA, Mittermeier CG, DaFonesca GAB, Kent J. 2000. Biodiversity hotspots for conservation priorities. Nature. 403:853–858.10.1038/35002501 [CrossRef], [PubMed], [Web of Science ®], [Google Scholar] ). The National Botanical Conservatory of the Mascarenes indicates that Vernonia fimbrillifera Less. is an endemic species from Reunion Island, locally named ‘bois de source’, which grows in the humid tropical forest (Lavergne and Véra 1989 Lavergne R, Véra R. 1989. Etude ethnobotanique des plantes utilisées dans la pharmacopée traditionnelle à La Réunion [Ethnobotanical study of plants used in the traditional pharmacopoeia of Reunion Island]. Paris: Agence de coopération culturelle et technique. [Google Scholar] ). To the best of our knowledge, neither phytochemical nor pharmacological works have been performed up to now on V. fimbrillifera. This study isolated and determined the structure of three antiplasmodial sesquiterpene lactones. Compounds were additionally tested in vitro for their cytotoxicity and their selectivity indices were established. [less ▲]

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See detailCyclotheonellazoles A–C, Potent Protease Inhibitors from the Marine Sponge Theonella aff. swinhoei
Issac, Michal; Aknin, Maurice; Gauvin-Bialecki, Anne et al

in Journal of Natural Products (2017), 80

he extract of a sample of the sponge Theonella aff. swinhoei collected in Madagascar exhibited promising in vitro antiplasmodial activity. The antiplasmodial activity was ascribed in part to the known ... [more ▼]

he extract of a sample of the sponge Theonella aff. swinhoei collected in Madagascar exhibited promising in vitro antiplasmodial activity. The antiplasmodial activity was ascribed in part to the known metabolite swinholide A. Further investigation of the extract afforded three unusual cyclic peptides, cyclotheonellazoles A–C (1–3), which contain six nonproteinogenic amino acids out of the eight acid units that compose these natural products. Among these acids the most novel were 4-propenoyl-2-tyrosylthiazole and 3-amino-4-methyl-2-oxohexanoic acid. The structure of the compounds was elucidated by interpretation of the 1D and 2D NMR data, HRESIMS, and advanced Merfay’s techniques. The new compounds were found to be nanomolar inhibitors of chymotrypsin and sub-nanomolar inhibitors of elastase, but did not present antiplasmodial activity. [less ▲]

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See detailAntimalarial Activities of Alkyl Cyclohexenone Derivatives Isolated from the Leaves of Poupartia borbonica
Ledoux, Allison ULiege; St-Gelais, Alexis; Cieckiewicz, Ewa ULiege et al

in Journal of Natural Products (2017), 80(6), 1750-1757

Bioactivity-guided fractionation of the ethyl acetate extract of the leaves of Poupartia borbonica led to the isolation of three new alkyl cyclohexenone derivatives 1−3, and named Poupartone A−C. The ... [more ▼]

Bioactivity-guided fractionation of the ethyl acetate extract of the leaves of Poupartia borbonica led to the isolation of three new alkyl cyclohexenone derivatives 1−3, and named Poupartone A−C. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopic data analysis and MS, whereas calculated and experimental ECD spectra were used to define the absolute configurations. These compounds were active against 3D7 and W2 Plasmodium falciparum strains with IC50 values between 0.55 and 1.81 μM. In vitro cytotoxicity against WI38 human fibroblasts and the human cervical cancer cell line HeLa (WST-1 assay) showed that these compounds were also cytotoxic, but no hemolytic activity was observed for the extract and pure compounds. An in vivo antimalarial assay was performed on the major cyclohexenone using P. berghei-infected mice at a dose of 15 mg/kg/day ip. The assay revealed growth inhibition of 59.1 and 69.5% at days 5 and 7 postinfection, respectively, although some toxicity was observed. Zebrafish larvae were used as a model to determine the type of toxicity, and the results showed cardiac toxicity. The methanol extract was also studied, and it displayed moderate antiplasmodial properties in vitro. This extract contained the known flavonoids, quercetin, 3′-O-hydroxysulfonylquercetin, quercitrin, and isoquercitrin as well as ellagic acid, which showed high to low activity against the 3D7 P. falciparum strain. [less ▲]

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See detailAntiplasmodial activity of Mezoneuron benthamianum leaves and identification of its active constituents
Jansen, Olivia ULiege; Tchinda, Alembert T.; Loua, Jean et al

in Journal of Ethnopharmacology (2017), 203(March), 20--26

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See detailANTICANCER, ANTIPLASMODIAL AND ANTITRYPANOSOMAL ACTIVITIES OF CRUDE EXTRACTS OF PLATANUS ORIENTALIS
Ebralidze, L.; Mskhiladze, Lasha; Ledoux, Allison ULiege et al

in World Journal of Pharmaceutical Research (2017), 6(3), 170-175

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See detailPotential Antimalarials from Tropical Plants and Natural Products
Frederich, Michel ULiege; Ledoux, Allison ULiege

Scientific conference (2016, November 16)

Malaria is caused by Plasmodium, a protozoan parasite transmitted by anopheles mosquitoes, and was responsible for 438 000 deaths worldwide in 2015 according to the last World Malaria report.1 The ... [more ▼]

Malaria is caused by Plasmodium, a protozoan parasite transmitted by anopheles mosquitoes, and was responsible for 438 000 deaths worldwide in 2015 according to the last World Malaria report.1 The resistance of parasites to available and affordable medicines has become a widespread problem in exposed countries, making the search of new antimalarial compounds still necessary. As the immeasurable therapeutic potential of plants is well established2, natural products could be an interesting source of new antimalarial drugs. Indeed, according Newmann and Cragg, more than 60% of the antiparasitic drugs discovered between 1981 and 2014 were unaltered naturals products (12.5%), natural products derivatives (31.3%) and synthetic drugs with a natural product pharmacophore (18.8%).3 Then, the pharmacological and phytochemical study of plants, especially from traditional pharmacopoeias can be of first interest to discovered new antimalarial compound and also to valorize the traditional knowledge. The first part of the talk will concern some examples of results obtained in the lab : the in vivo activity of strychnogucine B, which was isolated from strychnos icaja and semi-synthetized, the optimization of ellagic acid as a lead in the treatment of malaria and the validation of MIT from Mezoneuron benthamianum. In the second part of the talk, the work about Poupartia borbonica, an endemic plant from Reunion Island studied in the framework of a collaboration with the University of Reunion Island will be presented. [less ▲]

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