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., 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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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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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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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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Odonne, G., Stien, D., & Bourdy, G. (2010). Two piptocarphols from Pseudoelephantopus spicatus (Asteraceae) may explain its traditional use against cutaneous leishmaniasis amongst the Chayahuita (Peruvian Amerindians). In Planta Medica (Vol. 76, 1381).
Abstract: Chayahuita Amerindians are dwelling in north-west Peruvian Amazon. As they live in an endemic area of cutaneous and muco-cutaneous leishmaniasis, they developed a rich pharmacopoeia against those well recognized diseases [1]. Pseudoelephantopus spicatus (B. Juss. ex Aubl.) Rohr ex Gleason (Asteraceae) is one of the most used Chayahuita remedies against cutaneous leishmaniasis. In the course of evaluating those remedies against in vitro axenic amastigotes of Leishmania amazonensis, P. spicatus extract was found to be very active. Bioguided fractionation led to 3 active compounds (8,13-O-diacetyl-piptocarphol (1), 8-O-acetyl-13-O-ethyl-piptocarphol (2) and ursolic acid. Although these compounds had already been identified in other plants of the Vernoniae tribe (P. spicatus tribe) [2,3], none of them had been isolated from this species. 1 and 2 were found to be more active than amphotericin B against the parasite (IC50 for 1: 0.08±0.04µg/mL, 2: 0.14±0.05mg/mL, and 0.38µg/mL for amphotericin B), explaining at least partially the use of P. spicatus based remedies.
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Rodrigues, A., Espindola, S., Beauchêne, J., & Stien, D. (2010). Antifungal components from Amazonian long lasting heartwood. In Planta Medica (Vol. 76, 1172).
Abstract: About thirty Andira species have been described in America and Africa but most of them are found in Amazonian Rain Forest [1]. In French Guiana and Brazil A. surinamensis, A. coriaceae and A. inermis timbers (all named Saint-Martin Rouge in French) are commercialized for residential construction because of their excellent resistance to decay in ground contact [2]. In this study A. surinamensis heartwood was extracted with solvent of increasing polarities and extracts were evaluated against wood rotting fungi and human pathogens. Ethyl acetate extract proved strongly antifungal, showing that durable heartwood is a promising source of active metabolites for wood treatment and human health applications. Bioguided chemical fractionation allowed us to isolate five isoflavonoids including biochanin A [3].
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Rodrigues, A., Theodoro, P., Basset, C., Espindola, L., & Stien, D. (2010). Bio-inspiration in the discovery of active natural products: an example with the search of antifungal agents inspired from long-lasting woods. In Planta Medica (Vol. 76, 1293).
Abstract: Plant natural products have been perfected through evolution with respect to their specific biological roles (defense, elicitor, and so on) and are, therefore, an excellent starting point in the search for new biologically active chemicals. Hence, despite the progressive abandonment of the exploration of naturally sourced bioactive substances by the pharmaceutical industry, more than half of the drugs approved in the United States between 2005 and 2007 are natural products or natural product-derived drugs, five of which constituted the first members of new drug classes [1]. Clearly, chemical research into natural substances still has an important role to play in improving quality of life, and can play an important role by inventing innovative strategies to discover new bioactive compounds [1,2].
In the present work, we demonstrated that a bio-inspired approach for the identification of novel bioactive natural products represents a promising biotechnological tool for the development of new drugs. We have studied how natural defenses within decay-resistant wood can generate a large number of positive hits in the search for antimycotic agents. In addition, it was found from bioguided fractionation that ethyl acetate extracts of Sextonia rubra wood contain a relatively large proportion of antifungal metabolites rubrenolide (1) and rubrynolide (2), 1 being slightly more active than 2. The therapeutic potential of the above compounds will be discussed through the evaluation of their antifungal activities against 16 pathogenic fungi strains and their cytotoxicities towards KB cells.
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Royer, M., Herbette, G., Eparvier, V., Beauchêne, J., Thibaut, B., & Stien, D. (2010). Secondary metabolites of Bagassa guianensis Aubl. wood, a contribution to the understanding of the natural durability and to the chemotaxonomy of the Moraceae family with an unexplored genus. In Planta Medica (Vol. 76, 1375).
Abstract: In effort to explain wood durability of Moraceae plants family, a phytochemical study was undertaken on Bagassa guianensis. The phytochemical investigation of the ethyl acetate extract obtained from the heartwood led to the isolation of 18 secondary metabolites, including 6 moracins [the new 6-O-methyl-moracin M (3), 6-O-methyl -moracin N (4) and moracin Z (5); the known moracin M (1), moracin N (2) and moracin P (6)], 8 phenolic derivatives [the new (-)-epialboctalol (12), arachidin 4 (10) and the known alboctalol (11), trans-resveratrol (7), arachidin 2 (9), trans-oxyresveratrol (8) and artogomezianol (13)], the 3 known flavonoids steppogenin (14), katuranin (15), dihydromorin (16), the β-sitosterol (17) and the resorcinol (18). Comparison with literature data indicates that stilbenoids are presumably responsible for the natural resistance of the wood against fungi degradation. In addition, chemical composition points out that B. guianensis is closely related to Morus sp. in the phylogeny and should be placed within the Moreae s. s. tribe in the Moraceae family, accordingly to the latest Weiblen genoma-based classifications [1,2].
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