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Gibernau, M., & Barabé, D. (2012). Des fleurs à « sang chaud ». Pour la Science, Dossier n°77(Octobre-Décembre), 74–80.
Abstract: Comme les animaux, certaines plantes produisent de la chaleur. Leur température s'élève jusqu'à parfois 40 °C au-dessus de celle de l'air ambiant. Cette thermogenèse joue surtout un rôle dans les différentes étapes de la pollinisation.
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Casella, T., Eparvier, V., de Mesquita, M., Odonne, G., Espindola, L., & Stien, D. (2012). Bioactives products from leaves endophytes. In Planta Medica (Vol. 78, pp. 1045–1046).
Abstract: Leaves endophytes contribute to the natural defense of plant leaves, preventing both herbivory and invasion from superficial pathogens. It was therefore postulated that these microbes should produce antimicrobial and/or cytotoxic compounds. The isolated microorganisms belong to 14 different orders, the xylariales being the most represented (35 isolates, A). More than 20% of the extracts were considered active against at least one ...
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de Freitas, C., Silva, D., Kato, L., de Oliveira, C., Schuquel, I., da Silva, C., et al. (2012). New beta-carboline alkaloids from Galianthe ramosa (Rubiaceae). In Planta Medica (Vol. 78, 1182).
Abstract: Galianthe Griseb. (Rubiaceae, tribe Spermacoceae) is a genus comprising 50 endemic species in South America, its main center of diversity is located in central and southern Brazil. In our continuing chemical and biological investigations concerning Rubiaceae species from Cerrado, we report the isolation of new compounds 1 and 2, together with the known epi-catechin (3), ursolic and oleanolic acid. The alkaloid 2 inhibited the enzyme malato synthase from pathogenic fungus Paracoccidioides brasiliensis wich is considered an important target since it is not found in human.
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Dumontet, V., Litaudon, M., Olivon, F., Poullain, C., Rasoanaivo, P., Stien, D., et al. (2012). Evaluation of natural products as potential agrochemical agents with insecticide, fungicide and herbicide activities. In Planta Medica (Vol. 78, 1226).
Abstract: The present work aims to identify new promising plant sources, which could be exploited for their agrochemical properties. A total of 484 natural products from academic libraries were selected for screening against four fungal pathogens, five insects and two plants. On the basis of the hits founded and a literature survey, the flora of source countries (New Caledonia, French Guiana, Madagascar, Panama, South Africa and Greece) was analysed for plants containing the desired scaffolds. Lists of 1800 plant part samples were thus established. The plant parts collected generated 3600 extracts that are being evaluated.
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El Khil, M., Houel, E., Eparvier, V., & Stien, D. (2012). Development of a statistical tool to predict anticandidal activity of essential oils. In Planta Medica (Vol. 78, 1065).
Abstract: There is a general agreement that natural volatile compounds of essentials oils from plants provide a great potential for discovery of new antimicrobial drugs such as anticandidal ones. In this work, 60 commercial essential oils were analysed by GC/MS and their inhibitory activity against the growth of three Candida strains was evaluated. We then conducted a chemometric analysis and proposed a tool to predict their capacity to inhibit the Candida sp. developpment. Raw data were pretreated and normalised using MZmine2.2 software. It was possible to identify some of the natural compounds with anticandidal properties using two statistical tools in XLstat7.5: hierarchical clustering analysis (HAC) and principal component analysis (PCA). We highlighted that essential oils containing limonene, 1,8-cineole, linalool and linalyl acetate were mostly inactive, whereas eugenol, thymol, carvacrol, geraniol, geranial and neral as major components of the oils seems to be linked to an interesting anticandidal activity. Linear regressions showed a high correlation between the concentration of these molecules and their antifungal activity. Exceptions to these general tendencies could be characteristic of synergistic or antagonistic interactions.
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Faustin, M., Maciuk, A., Lebrini, M., Robert, F., Roos, C., & Figadere, B. (2012). Isolation of Geissospermum laeve alkaloids by pH-zone refining centrifugal partition chromatography for metal corrosion studies. In Planta Medica (Vol. 78, 1270).
Abstract: Control of metal corrosion is of technical, economical, environmental, and aesthetical importance. The use of corrosion inhibitors is one of the best options to protect metals and alloys from corrosion. The environmental toxicity of synthetic inhibitors has prompted the search for green compounds. Plant extracts have become important as an environmentally acceptable, readily available and renewable source for a wide range of biodegradable, heavy metals-free inhibitors. Among natural compounds, alkaloids have very high corrosion inhibition efficiency. An alkaloidic extract of Geissospermum laeve (Apocynaceae) has been fractionated by centrifugal partition chromatography using the pH-zone refining mode in order to investigate the effect of isolated alkaloids on C38 steel corrosion in HCl 1M. Indole alkaloids were identified by LC-MS, 1H and 13C NMR.
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Houel, E., Bertani, S., Bourdy, G., Deharo, E., Jullian, V., Valentin, A., et al. (2010). Quassinoid constituents of Quassia amara L. (Simaroubaceae) leaf herbal tea. Impact on its antimalarial activity and cytotoxicity. In Planta Medica (Vol. 76, pp. 1381–1382).
Abstract: French Guiana records high malaria incidence rates. The traditional antimalarial remedy most widespread and still very much in use there is a tea made out from Quassia amara mature leaves. The antimalarial activity of this preparation was assessed [1] and in order to optimize the in vitro activity, different types of preparation have been realized and tested. The most active in vitro preparation is an infusion of fresh young leaves. It demonstrated a very good activity, in vitro as well as in vivo [2]. A known quassinoid, simalikalactone D (SkD), was identified as the active compound, with an IC50 value of 10 nM against FcB1 Plasmodium falciparum chloroquine resistant strain in vitro [3]. Our next objective was to assess whether it could be contemplated to recommend this young leaves tea for treatment against malaria, since it seemed from literature precedent that SkD was also cytotoxic to a number of cellular lineages [4,5]. We then characterized and quantified the antiparasitic and cytotoxic activities of all the constituents. Several quassinoids were isolated and characterized in the tea: SkD, quassin, neoquassin, and picrasins B, H, I (new) and J (new), SkD being responsible of both antiplasmodial activity and cytotoxicity. In addition, in the context of an antimalarial treatment, it appeared that the dose necessary for obtaining a curative antimalarial effect is close to the toxic dose of an SkD analogue, bruceantin. Prior to emitting a definitive conclusion, a clinical study in humans similar to the one done with bruceantin [6] should be performed.
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Houel, E., Rodrigues, A., Jahn-Oyac, A., Bessiere, J., Eparvier, V., Deharo, E., et al. (2012). In vitro antifungal activity of Otacanthus azureus (Linden) Ronse essential oil alone and in combination with azoles. In Planta Medica (Vol. 78, 1202).
Abstract: We determined the chemical composition and investigated the antifungal activity of Otacanthus azureus (Linden) Ronse essential oil alone or combined with azoles antifungals against a range of human yeasts and dermatophytes. The oil was shown to be composed in majority of sesquiterpenes. Using broth microdilution techniques, it was found to exert interesting in vitro antifungal activities, more particularly against human dermatophytes, with minimum inhibitory concentrations as low as 4µg/ml against a clinical isolate of Trichophyton rubrum. The analysis of the combined effect of this oil with azoles highlighted a pronounced synergism between the oil and ketoconazole or itraconazole, against Candida albicans, C. parapsilosis and Trichophyton mentagrophytes, with fractional inhibitory concentration indices in the 0.1–0.5 range. Interestingly, the oil showed no cytotoxicity on VERO cells (ED50>100µg/ml). According to these results, O. azureus essential oil may be considered a promising natural product in the treatment of human mycoses, more particularly those originating from dermatophytic fungi. Also, it is likely to reduce the minimum effective dose of ketoconazole and itraconazole against Candida species, thus minimizing the side effects of these drugs, and the risk to develop resistances.
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Le Ven, J., Eparvier, V., Litaudon, M., & Gueritte, F. (2010). Isolation of bioactive aporphinoid alkaloids in Oxandra asbecki (Annonaceae). In Planta Medica (Vol. 76, 1287).
Abstract: Since prehistoric times, humans beneficially used natural resources for their daylife needs. Plants are able to synthesize complex molecules and consequently have a unique chemical diversity. This is a source of inspiration for new drugs discovery. Dyrk1A kinase is a target used in research on Alzheimer's disease. Inhibition of this kinase is associated with treating symptoms of this disease [1,2]. In France, the annual number of new cases is 230 000. The prevalence is expected to double in industrialized countries and quadruple in developing countries in the coming decades. The development of a better diagnosis and treatment is essential. The Annonaceae is a large family of tropical plants that have been investigated intensively. There exist 38 species in Oxandra genus and Oxandra asbecki species in Venezuela and in primary forests of French Guiana. To the aim of discovering new bioactive plants from French Guiana, Oxandra asbecki was selected for phytochemical study because of its potent inhibition of DyrK1A kinase. Bioassay-directed fractionation of the ethyl acetate extract provided three bioactive alkaloids. We isolated three aporphinoid alkaloids and show for the first time an strong activity (with micromolar IC50) of Velutamin under two kinase: CDK1 and DyrK1A, and activity of Aristolactam AII on DyrK1A kinase.
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Nirma, C., Rodrigues, A., Basset, C., Stien, D., & Eparvier, V. (2010). Isoflavonoids with insecticide and larvicide activities from Muellera frutescens Standl. In Planta Medica (Vol. 76, pp. 1197–1198).
Abstract: Many plants of the Fabaceae family, are used as fish poisoning and insecticides [1,2]. The genus Muellera in this family is represented by only seven species of climbers and trees and is distributed over south and central America. In 1984, Geesink proposed to consider Muellera as Lonchocarpus synonymous [3]. The Lonchocarpus genera is well known in French Guiana because of its traditional utilization as a fish poisoning [4]. However, one study only reported ethnobotanical use of M. frutescens as an ichtyotoxic plant. Furthermore, no ethnopharmacological use or biological activity data was ever reported in the literature for this plant. Many chemical studies dealing with Lonchocarpus genera have been published [5,6,7]. Phytochemical investigation of barks, stems and rarely leaves described isolation of active isoflavonoids named rotenoids. This study aims at conducting a phytochemical survey of Muellera frutescens in order to evaluate whether or not Muellera is closely related to Lonchocarpus and eventually isolate new bioactive secondary metabolites. Three different extracts (hexane, ethyl acetate and methanol) of bark, roots and leaves were prepared and tested on various biological assays. We discovered insecticide and larvicide activities for all extracts, and none of them exhibited cytotoxicity on human cells. The bioguided fractionation of the most active extract (bark hexane extract) allowed us to isolate eight isoflavonoids, the structures of which were elucidated by spectroscopic methods. It was found that Muellera is indeed closely related to Lonchocarpus, therefore corroborating Geesink's proposal.
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