Upon activation under superacid conditions, functionalized tailor-made N-SCF sulfenamides served as reagents for the trifluoromethylthiolation of aromatic amines. This method has a broad substrate scope and can be used for the late-stage functionalization of complex molecules such as alkaloids or steroids. Mechanistic studies based on in situ low-temperature NMR spectroscopy revealed the involvement of dicationic superelectrophilic intermediates.
RésuméObjectif : une étude ethnobotanique des plantes tinctoriales a été menée de juin 2010 à novembre 2011 dans le but de les inventorier et de réaliser un screening chimique sur trois espèces sélectionnées selon un certains nombre de critères. Méthodologie et résultats : Une enquête ethnobotanique pour les plantes tinctoriales du Congo réalisée de juillet 2010 à novembre 2011auprès des herboristes, des artisans teinturiers et des détenteurs de savoir traditionnel, et compléter par une revue bibliographique des plantes de la région Afrique Centrale a permis d'inventorier cent cinquante (150) plantes utilisées comme colorants par les populations de la région. Trois de ces plantes, Grewia coriacea Mast (Malvaceae -Grewioideae), Harungana madagascariensis Lam ex Poir. (Hypericaceae), Annickia chlorantha Oliv. (Annonaceae) ont été sélectionnées au regard de leur fréquence d'utilisation pour un screening phytochimique afin d'en évaluer les propriétés tinctoriales. Les flavonoïdes, les tanins, les anthocyanes, les anthraquinones et les alcaloïdes ont été mis évidences. Conclusion et application : l'inventaire ethnobotanique a permis de nous rendre compte que les plantes tinctoriales sont largement utilisées par les populations à la fois en teinture et en médecine traditionnelle. L'analyse phytochimique des trois espèces sélectionnées présage que celles-ci peuvent être des matières premières pour la production des colorants. Mots clés : Enquête ethnobotanique, plantes tinctoriales, Grewia coriacea, Harungana madagascariensis, Annickia chlorantha, screening phytochimique.
AbstractObjective: An ethnobotanical survey of plants used for dyeing was performed from July 2010 to November 2011 in Congo for to inventory them and to achieve a phytochemial screening on three species selected by some number of criteria. Methodology and Results: Interviews with herbalists, artisans, dyers and holders of traditional knowledge were done. A complete literature review of the plants of the Central African region has an inventory of one hundred and fifty (150) plants used as dyers for the people of the region. Three of these plants, Grewia coriacea Mast (Malvaceae -Grewioideae), Harungana madagascariensis Lam ex Poir. (Hypericaceae), Annickia chlorantha Oliv. (Annonaceae), were selected in terms of their frequency of use for a phytochemical screening to assess their dyeing properties. Conclusion and application: An ethnobotanical survey permitted to give account that the dye plants are used extensively by the population in dye and in traditional medicine. The phytochemical analysis of the three species selected omen that those can be here raw materials for the production of the dyes.
The aerial parts of Momordica charantia L. are very often used in traditional Congolese medicine for their multiple virtues. Our study focused on the identification of a well-known antidiabetic molecule: the charantine and also the antidiabetic properties of the ethanol extract of M. charantia L. After being treated with MSTFA (N-Methyl-N-(trimethylsilyl) trifluoroacetamide) and using gas chromatography-Mass spectrometry, the analysis of the extract of the leafy stem of M. charantia L., var abreviata, harvested in Brazzaville (Congo) led to the identification of a recognized antidiabetic molecule stigmasterol glucoside or β sitosterol: the charantine. When testing the ethanolic extract on albino Wistar rats that were made diabetic by injecting the streptozotocin, this reduces glycemia significantly by 51.62% after three hours. The significant results of the antidiabetic tests and the identification of the charantine in the plant justify its use in the traditional medicine in Congo Brazzaville.
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