Etude physico-chimique et minéralogique comparative des attapulgites de Mbodiène (Sénégal) et de Mormoiron (France)

La valorisation des ressources locales constitue un impératif afin d’atteindre des objectifs de développement durable. Cette étude a consisté à évaluer les caractéristiques physiques, chimiques et minéralogiques d’une argile provenant de Mbodiène (Sénégal), l’attapulgite, comparativement avec un médicament antidiarrhéique, constitué d’attapulgite, dénommé Actapulgite®. L’échantillon d’attapulgite brute a été purifié avec une solution de HNO3 1M. Une étude morphologique effectuée par visualisation à la Microscopie Electronique à Balayage a montré pour les deux argiles étudiées, une structure fibreuse caractéristique de la palygorskite, représentant le minéral dominant. L’analyse chimique par la spectrométrie à fluorescence X a donné pour l’attapulgite purifiée : 65,69% Si, 7,89% Al, 5,92% Fe, 17,90% Mg, 0,43% Ca et 0,93% K contre respectivement 63,98 % Si, 12,92% Al, 10,32% Fe, 6,20% Mg, 2,48% Ca et 2,25% K pour l’Actapulgite®. La diffraction aux rayons X a montré une présence de palygorskite, quartz et carbonates dans les échantillons étudiés. L’étude des isothermes d’adsorption a montré une surface spécifique nettement plus élevée pour l’attapulgite purifiée, 138,96 m2.g-1 contre 98,72 m2.g-1 pour l’Actapulgite®. Ces résultats ont montré que l’attapulgite de Mbodiène pourrait être utilisée comme antidiarrhéique orale après lavage à l’eau et séchage.© 2016 International Formulae Group. All rights reservedMots clés: Argile, attapulgite, antidiarrhéique, SénégalEnglish Title: Physico-chemical and mineralogical comparative study of attapulgites Mbodiène (Senegal) and Mormoiron (France)English AbstractThe development of local resources is imperative to achieve sustainable development goals. This study was to assess physical, chemical and mineralogical characteristics of a clay from Mbodiène (Senegal), named attapulgite, compared with Actapulgite® (antidiarrheal drug), composed of attapulgite. A sample of attapulgite from Mbodiène was purified with a 1M HNO3 solution to remove impurities including carbonates. A morphological study using Scanning Electron Microscopy showed for both types of clay studied, a fibrous structure characteristic of palygorskite which represent major mineral. Chemical analysis by XRF spectrometry gave for purified attapulgite: 65.69% Si, 7.89% Al, 5.92% Fe, 17.90% Mg, 0.43% Ca and 0.93% K against respectively 63.98% Si, 12.92% Al, 10.32% Fe, 6.20% Mg, 2.48% Ca and 2.25% K for Actapulgite®. X-ray diffraction showed the presence of palygorskite, quartz and carbonates for both samples studied. The study of adsorption isotherms showed a significantly higher surface area for purified attapulgite, 138.96 m2.g-1 versus 98.72 m2.g-1 for Actapulgite®. These results have shown that Mbodiène attapulgite compared to Actapulgite®, could be used as an oral antidiarrheal after washing with water and drying.© 2016 International Formulae Group. All rights reserved.Keywords: Clay, attapulgite, antidiarrheal, Senega

A Method for LC-MS/MS Profiling of Coumarins in Zanthoxylum zanthoxyloides (Lam.) B. Zepernich and Timler Extracts and Essential Oils

The metabolites from the coumarin class, present in tissues of plants belonging mainly to the Rutaceae and Apiaceae families, included compounds with high chemical diversity such as simple coumarins and furocoumarins. These health-promoting components are recognized for their valuable biological activities in herbal preparations but also for their phototoxic effects. In this work, a targeted liquid chromatography (LC) coupled with tandem mass spectrometry (MS2) was developed for the screening of 39 reference standards of coumarins and furocoumarins in essential oils and plant extracts. Chromatographic separation was accomplished on reversed phase column using water/acetonitrile as the mobile phase and detection was performed on a hybrid QqQ/linear ion trap spectrometer fitted with an atmospheric pressure chemical ionization (APCI) source operating in positive ion mode. This analytical approach was applied to investigate the coumarin compositions of fruit essential oils and methanolic extracts obtained from separated parts (fruit, leaf, stem, trunk, and root) of Zanthoxylum zanthoxyloides. Ten coumarins and six furanocoumarins were reported in this species and data analyses were used to assess the suitability of these compounds to the metabolomics-based differentiation of plant organs. The quantification criteria of the metabolites in extract samples included linearity, limit of quantification, limit of detection, and matrix effect were validated. As reported for other species of the Rutaceae family, the concentration of coumarins was drastically higher in Z. zanthoxyloides fruits than in other plant organs

Chemical composition and biological activities of two species of the genus Zanthoxylum (Z. zanthoxyloides and Z. leprieurii) the flora of Senegal

Les travaux de ce doctorat ont été menés dans le cadre d’une convention de cotutelle internationale entre l’Université Cheikh Anta Diop de Dakar (Sénégal) et l’Université de Corse (France). Ils s’inscrivent dans un objectif général visant à la caractérisation et à la valorisation de la chimio-biodiversité des ressources végétales. Dans ce contexte, nous nous sommes intéressés à deux espèces du genre Zanthoxylum poussant à l’état spontané au Sénégal : Z. zanthoxyloides et Z. leprieurii. Notre but principal était de produire des connaissances scientifiques sur la composition chimique (constituants volatils et phénoliques) et les propriétés biologiques (antimicrobiennnes et antioxydantes) relatives aux huiles essentielles et/ou aux extraits de ces deux taxons. A l’instar d’autres plantes de la famille des Rutacées telles que les espèces du genre Citrus sp., ces deux espèces de Zanthoxylum pourraient être utilisées - sous forme d’huiles essentielles ou d’extraits - dans les produits cosmétiques ou les préparations médicinales pour leurs activités biologiques et/ou leurs propriétés parfumantes.Les huiles essentielles ont été extraites par hydrodistillation à l’aide d’un appareil de type Clevenger et analysées par GC/MS et GC/FID. L’analyse des compositions en volatils des différentes parties végétales des deux taxons (fruits, tiges, feuilles, écorces de racines et du tronc) a montré que les composés volatils se concentrent dans les fruits et que les parties aériennes et souterraines de Z. leprieurii présentent des concentrations en constituants volatils plus importantes que celles de Z. zanthoxyloides. Les profils chromatographiques des huiles essentielles obtenues à partir des organes séparés de Z. zanthoxyloides et Z. leprieurii ont également montré une variabilité chimique interspécifique. L’étude comparative de la composition chimique des huiles essentielles de fruits en fonction des zones de récolte a montré une variabilité chimique intraspécifique aussi bien pour Z. zanthoxyloïdes que pour Z. leprieurii. L’influence du stade de maturité sur la variabilité chimique des huiles essentielles de Z. leprieurii s’est traduite par une augmentation du rendement et aussi par des variations quantitatives des compositions volatiles. Enfin, l’huile essentielle des fruits de Z. zanthoxyloides s’est avérée active sur S. aureus ainsi que sur C. albicans.Par ailleurs, les compositions phénoliques (coumarines et flavonoïdes) et les activités biologiques des extraits des deux taxons ont été étudiées. Dans un premier temps, une méthode de LC-MS2 pour la caractérisation des coumarines a été développée. Cette approche analytique a permis l’identification et la quantification de 16 coumarines dans Z. zanthoxyloides. Neuf d’entre elles ont été décrites pour la première fois dans cette espèce végétale. La concentration de coumarines est beaucoup plus élevée dans les fruits que dans les autres organes végétaux. Cette concentration a été considérablement réduite par l’hydrodistillation en comparaison de l'extraction méthanolique. Par ailleurs, 9 flavonoïdes (huit pour la première fois) ont été identifiés et quantifiés dans ces mêmes extraits, dont trois flavonoïdes glycosylés et un flavonol présents à des teneurs importantes. Leurs concentrations sont beaucoup plus élevées dans les écorces de racines, les écorces du tronc et les fruits. Contrairement à Z. zanthoxyloides, dans les différents extraits de Z. leprieurii seulement une coumarine (scoparone) et quatre flavonoïdes ont été identifiés. Nous avons également évalué les activités biologiques des différents extraits végétaux. Il apparait que les extraits de feuilles et des écorces du tronc de Z. zanthoxyloides présentent un pouvoir antioxydant modéré alors que les autres extraits étudiés exhibent de faibles activités pour les deux taxons. Enfin, la meilleure activité sur un spectre large de bactéries a été obtenue avec l’extrait de racines de Z. zanthoxyloides.The work of this PhD was carried out within the framework of an international co-supervision agreement between the University of Cheikh Anta Diop (Senegal) and University of Corsica (France). A general objective aimed at the characterization and valorization of chemo-biodiversity of plant resources. In this context, we have studied two species of the genus Zanthoxylum growing spontaneously in Senegal: Z. zanthoxyloides and Z. leprieurii. Our main goal was to produce scientific knowledge on the chemical composition and biological properties of essential oils and/or extracts of these two taxa. Like other plants of the Rutaceae family such as species of the genus Citrus sp., these two plants of Zanthoxylum genus could be used - in the form of essential oils or extracts - in cosmetics or medicinal preparations for their biological activities and/or perfuming properties.The essential oils were obtained by hydrodistillation from the separated organs of Z. zanthoxyloides and Z. leprieurii. Analysis of the volatile compositions of different plant parts from the two taxa showed that the volatile compounds are concentrated in the fruits and that the aerial and subterranean parts of Z. leprieurii have higher volatile constituent concentration than those of Z. zanthoxyloides . The chromatographic profiles of the essential oils obtained from the separated organs of Z. zanthoxyloides and Z. leprieurii showed interspecific chemical variability. The comparative study of the chemical composition of fruit essential oils according to the harvesting zones showed an intraspecific chemical variability for Z. zanthoxyloides as well as Z. leprieurii. The influence of the maturity stage on the chemical variability of the essential oils of Z. leprieurii has resulted in an increase of oil yield and also quantitative variations of volatile compositions. Finally, the essential oil from the fruits of Z. zanthoxyloides and more particularly its rich-alcohol fraction (octanol and decanol) was found active against S. aureus as well as C. albicans.Moreover, the phenolic compositions (coumarins and flavonoids) and the biological activities (antioxidant and antibacterial) of the extracts from two taxa were evaluated. In a first step, an LC-MS2 method for the characterization of coumarins was developed. This analytical approach allowed the identification and quantification of 16 coumarins in Z. zanthoxyloides. Nine of these metabolites have been described for the first time in this plant species. The concentration of coumarins is much higher in fruits than in other plant organs. This concentration was considerably reduced by the hydrodistillation in comparison with the methanolic extraction. In addition, 9 flavonoids (eight for the first time) were identified and quantified in these extracts, including three glycosylated flavonoids and one flavonol present in high contents. Their concentrations are much higher in root barks, trunk barks and fruits than in other plant parts. Unlike Z. zanthoxyloides, only one coumarin (scoparone) and four flavonoids were identified in Z. leprieurii extract. The antioxidant and antibacterial activities of all plant extracts we also measured. It appears that the leaf and trunk bark extracts of Z. zanthoxyloides have a moderate antioxidant power whereas the other extracts exhibited low antioxidant properties. The antimicrobial activity of Z. zanthoxyloides extracts was evaluated against 32 Gram-positive bacteria and 4 Gram-negative bacteria. The best activity on a wide spectrum of bacteria was obtained with the root extract, it was found to be active on 20 strains with MIC values ranging from 75 to 625 μg/ml

A Method for LC-MS/MS Profiling of Coumarins in Zanthoxylum zanthoxyloides (Lam.) B. Zepernich and Timler Extracts and Essential Oils

The metabolites from the coumarin class, present in tissues of plants belonging mainly to the Rutaceae and Apiaceae families, included compounds with high chemical diversity such as simple coumarins and furocoumarins. These health-promoting components are recognized for their valuable biological activities in herbal preparations but also for their phototoxic effects. In this work, a targeted liquid chromatography (LC) coupled with tandem mass spectrometry (MS2) was developed for the screening of 39 reference standards of coumarins and furocoumarins in essential oils and plant extracts. Chromatographic separation was accomplished on reversed phase column using water/acetonitrile as the mobile phase and detection was performed on a hybrid QqQ/linear ion trap spectrometer fitted with an atmospheric pressure chemical ionization (APCI) source operating in positive ion mode. This analytical approach was applied to investigate the coumarin compositions of fruit essential oils and methanolic extracts obtained from separated parts (fruit, leaf, stem, trunk, and root) of Zanthoxylum zanthoxyloides. Ten coumarins and six furanocoumarins were reported in this species and data analyses were used to assess the suitability of these compounds to the metabolomics-based differentiation of plant organs. The quantification criteria of the metabolites in extract samples included linearity, limit of quantification, limit of detection, and matrix effect were validated. As reported for other species of the Rutaceae family, the concentration of coumarins was drastically higher in Z. zanthoxyloides fruits than in other plant organs

The Essential oil of Eucalyptus alba L. Growing on the Salt Zone of Fatick (Senegal) as a Source of 1,8Cineole and Their Antibacterial Activity

Members of the genus Eucalyptus are potential sources of number of commercial essential oils and aromachemicals. In present study, the essential oils isolated by hydrodistillation from the leaves of Eucalyptus alba were analyzed by GC-FID and GC-MS. Essential oil yields ranged from 2.41 to 4.35%. In total 18 constituents were identified, accounting for 99.0 to 99.7% of the total compositions. 1,8-cineole was present in all samples as the major component (76.5-88.1%). In addition to this compound, others that were found including limonene (3.8–8.6%), α-terpineol (1.4–2.8%), globulol (1.3–6.3%) and α-pinene (1.5–1.8%). The essential oil showed a strong antibacterial activity against S. aureus ATCC 29213 which is translated by an MIC of 1.25 mg/mL and good activity against E. coli ATCC 25922 (6.25 mg/mL) and E. faecalis ATCC 29212 (6.25 mg/mL). To our knowledge, our study is the first report of E. alba essential oils characterized by a high 1,8-cineole content (>76.5%). They may have potential applications in food and pharmaceutical products. Keywords: Eucalyptus alba, essential oils, antibacterial activity, 1,8-cineole and GC-S

The Flavonoid Compounds from Zanthoxylum leprieurii Guill. et Perr (Rutaceae) Extracts and their Antioxidant Activity against ABTS•+

Screening of flavonoid compounds in fruit, leaf, stem and root bark extracts of Z. leprieurii was achieved by liquid chromatography (LC) coupled with tandem mass spectrometry (MS2). Among the 186 reference compounds tested, four flavonoids were identified in one or other of the organ extracts from each plant (fruit, leaf, root barks and stem): neodiosmin and hesperidin were identified in all extracts. The presence of datiscin was reported only in leaves while that of rutin was identified in fruits and leaves. Of these four flavonoids, three (neodiosmin, datiscin and rutin) are detected for the first time in Z. leprieurii. The antioxidant properties of different extracts were tested regarding their scavenging activities on ABTS•+ radical. Fruit, leaf and stem extracts had low antioxidant potential and root bark extracts exhibited very low antioxidant activity. Keywords: Zanthoxylum leprieurii, flavonoids, LC-MS/MS and antioxidant activity

Chemical Constituents and Antimicrobial and Antioxidant Activities of Essential Oil from Dried Seeds of Xylopia aethiopica

The study aimed to investigate the chemical composition and antimicrobial and antioxidant activities of the essential oil from dried seeds of Xylopia aethiopica. The essential oil was obtained by hydrodistillation and analyzed by GC/FID and GC/MS. The essential oil yield was 1.35%. Forty-nine compounds were identified in the essential oil with 1,8-cineole (16.3%), β-pinene (14.8%), trans-pinocarveol (9.1%), myrtenol (8.3%), α-pinene (5.9%), and terpinen-4-ol (5.6%) as major components. The antimicrobial activity of this essential oil was studied using disk diffusion and broth microdilution methods on four bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa) and one fungus (Candida albicans). The essential oil exhibited excellent activity against S. aureus, E. faecalis, and C. albicans and moderate activity against E. coli. Among all strains tested, C. albicans showed the best sensitivity with a MIC of 50 mg/mL. The antioxidant activity was examined using a DPPH-free radical scavenging assay. The essential oil of X. aethiopica showed low antioxidant activity (IC50 = 784.604 ± 0.320 mg/mL) compared to that of ascorbic acid and the reference compound (IC50 = 0.163 ± 0.003 mg/mL). The results indicate that consumption of X. aethiopica seeds can reduce the virulence of food-borne pathogens and their resistance to antibiotics

Evaluation of antibacterial and antifungal activities of N-benzylthienopyrimidinone derivatives

This study is part of the biological investigation of the chemical library of molecules already described by the Laboratory of Organic Chemistry and Therapeutic Chemistry of the University of Bordeaux. The main objective was to explore the contribution of a thienyl moiety attached to the pyrimidinone nucleus, in the expression of an antimicrobial activity. The structural modifications mainly concerned the conservation or not of  the  benzo fragment attached to the thienyl, the saturation or not in position-1,2 of the pyrimidinone ring, the substitution on N-benzyl with more or less lipophilic units, the modification of the orientation of the thienyl fragment with, on  the one hand, the compounds in which the sulfur is located near the N1 nitrogen (series of thieno[2,3-d]pyrimidin-4-ones) and on the other hand, compounds in which the sulfur is located near the ketone group (series of thieno[3,2-d]pyrimidin-4-ones). In general, thienyl fragment with sulfur located near the ketone group and the unsaturated pyrimidinone nucleus in the 1,2-position, seem to promote a broad spectrum of antibacterial activity, with compound 9c which is active on both Gram + bacteria and Gram – bacteria studied. The same pattern was observed for antifungal activity, which is maximum with the compounds of the thieno[3,2-d]pyrimidin-4-ones series for an MIC of 31.25 μg/ml on the strains of Candida albicans and Candida kruzei studied. Keywords: Thienopyrimidinones, antibacterial activity, antifungal activity